Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Roughness Digital Characterization and Influence on Wear of Retrieved Knee Components

Roughness Digital Characterization and Influence on Wear of Retrieved Knee Components applied sciences Article Roughness Digital Characterization and Influence on Wear of Retrieved Knee Components 1 , 2 3 3 Saverio Affatato * , Alessandro Ruggiero , Silvia Logozzo and Maria Cristina Valigi Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, nr. 132, 84084 Fisciano, Italy; ruggiero@unisa.it Department of Engineering, University of Perugia, Via Goffredo Duranti, 93, 06125 Perugia, Italy; silvia.logozzo@unipg.it (S.L.); mariacristina.valigi@unipg.it (M.C.V.) * Correspondence: affatato@tecno.ior.it Featured Application: This paper is focused on the roughness of lateral and medial condyles used to digitally reconstruct the 3D topography of surfaces, giving insights about the wear behavior. Abstract: Tribological performance of knee components are strongly related to the surface character- istics. Primarily, the roughness and its 3D distribution on the surfaces affect the joint performance. One of the main limitations related to the tribological study of knee prostheses is that most of the research studies report in vitro or in silico results, as knee retrievals are difficult to find or are too damaged to be analyzed. This paper is focused on the roughness characterization of retrieved metal femoral components of total knee replacements (TKR) by means of a rugosimeter and involving digital methods to reconstruct the 3D topography of the studied surfaces. The aim of this study is to Citation: Affatato, S.; Ruggiero, A.; investigate how changes and distribution of roughness are correlated between the medial vs. the Logozzo, S.; Valigi, M.C. Roughness lateral part and how the resulting digital topography can give insights about the wear behavior. Digital Characterization and Influence on Wear of Retrieved Knee Keywords: total knee arthroplasty; digital biotribology; 3D topography; roughness characterization; Components. Appl. Sci. 2021, 11, wear maps 11224. https://doi.org/10.3390/ app112311224 Academic Editor: Alessandro Gasparetto 1. Introduction Total knee replacement (TKR) is an elective surgical procedure in orthopedic surgery Received: 11 October 2021 worldwide to relieve pain in patients with osteoarthritis and to improve function and Accepted: 23 November 2021 restore a good quality of life for patients [1]. In general, TKR consists of three main Published: 26 November 2021 components: a metal femoral part, a metal tibial plate, and a polyethylene tibial insert. A knee replacement may fail over time and may need a second surgery for a variety of issues. Publisher’s Note: MDPI stays neutral Evidence from previous studies demonstrates that a TKR can last, at most, 15–20 years [2]. with regard to jurisdictional claims in It is known that the success and longevity of a knee implant is affected by the characteristics published maps and institutional affil- of patients such as age, weight, gender, and activity level [3–6]. Surface damage and wear iations. are the main threats to the long-term survival of a TKR [7,8]. Failure most commonly occurs due to fatigue and adhesive wear, which are responsible for the generation of micro particulate debris that, in turn, cause osteolysis around the replacements, ultimately leading to loosening and failure of the TKR [7–9]. The survival rate of total knee replacements Copyright: © 2021 by the authors. (TKR) has been reported to increase along with the development of advanced technologies Licensee MDPI, Basel, Switzerland. and operative techniques [10–12]. This article is an open access article Tribological aspects of knee components are strongly related to the surface conditions. distributed under the terms and For instance, the 3D distribution of roughness and the surface topography affect the joint conditions of the Creative Commons effectiveness. Many tribological studies regarding knee implants were performed in vitro Attribution (CC BY) license (https:// or in silico conditions [13–16], as knee retrievals are difficult to find or are too damaged to creativecommons.org/licenses/by/ be analyzed. 4.0/). Appl. Sci. 2021, 11, 11224. https://doi.org/10.3390/app112311224 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 11224 2 of 10 In the case of in vitro studies, the femoral or tibial inserts undergo wearing cycles at dedicated simulators in laboratory conditions, trying to replicate general motion activities, whereas in silico studies involve computational analyses of knee virtual models. In vitro and in silico tribo-characterization of prostheses are surely useful but they are rarely as predictive as in vivo studies. Nevertheless, the advantage of in vitro and in silico analyses is that all the phenomena are repeatable. This study reports relevant damage mechanisms seen in retrieved metallic femoral components of total knee replacements accompanied with failure. Retrieved knee implants were obtained from the Register of Explant of Orthopedic Prostheses (REPO, IRCCS Is- tituto Ortopedico Rizzoli). To limit the effects of the prosthetic design on the roughness measurements, 18 prostheses of the same prosthetic model were selected to minimize pos- sible confounding factors. Although most of the implants were removed due to infection, the surface analysis was essential to analyze the surface damage mode of a short-term implants. The aim of this paper is to perform a roughness characterization of the retrieved components to evaluate how changes and distribution of roughness are correlated between the medial vs. the lateral part and how the resulting digital topography can give insights about the wear behavior. The qualitative description of the severity and location of surface damage can explain the damage mechanism on the early-retrieved implants. The surface characterization was performed using a Hommel Werke rugosimeter to evaluate the surface roughness and the texture of these components in different locations over the lateral and medial areas. The rugosimeter allowed to acquire the target surfaces point by point. In addition, a Gaussian filter was involved as a digital method to reconstruct the 3D topography of the studied surfaces, which can be read as a 3D wear map, in terms of qualitative distribution considering the strict correlation with the roughness. 2. Materials and Methods 2.1. Process of Selection The sample implants were selected from REPO (Register of Explants of Orthopedic Prosthesis) which collects and categorizes medical devices explanted at the IRCCS Rizzoli Orthopaedic Institute (IOR). Starting from about 186 knee prosthesis explants, the largest group of prostheses with the same model was chosen by two independent observers (AM and AT) to keep a low variability and to limit the effects of the prosthetic design on the roughness measurements. Moreover, only the prostheses with particular evidence of scratches, pitting, or evident metal transfer were chosen for the analyses as the other ones were not significantly worn. In the end, 18 metallic femoral knee prostheses of the NexGen- LPS-Flex Fixed-Zimmer model, which were implanted from 2006 to 2016, remained for the roughness characterization. This kind of implant is a posterior stabilized prosthesis designed to accommodate a greater range of motion for appropriate patients. In this fixed configuration, the metallic tibial component is fixed to the tibial bone while the menisci are press-fit on the tibial plate. Major details about the sample condyles are given in Table 1. 2.2. Roughness Measurements and 3D Image Generation The wear analysis was performed by means of surface roughness and topographic measurements. All the retrieved specimens were analyzed on three different areas, cor- responding to the position of the knee during walk (30 and 60 ) or at rest (0 ). An area of interest of 1.5 mm  1.5 mm (2.25 mm ) was taken into account for each angle and on medial and lateral compartments. Figure 1 shows the measured areas on each prosthesis. Appl. Sci. 2021, 11, 11224 3 of 10 Table 1. Specimen selection, patient characteristics, follow up, and prosthesis size-number. Pz Gender Weight (kg) Height (cm) Side Diagnosis Reason for Revision F.U. (Years) Size #1 F 80 160 Right Fracture Septic loosening 1.5 3 #2 M 94 170 Left Unknown Septic loosening 0.7 3 #3 M 71 170 Right Other Aseptic loosening 2.5 3 #4 F 74 166 Left Aseptic loosening Aseptic loosening 2.1 3 #5 F 78 164 Right Arthrosis Septic loosening 1.0 3 #6 M 106 180 Left Arthrosis Aseptic loosening 1.6 4 #7 M 50 NA Left Post-traumatic arthrosis Septic loosening 0.2 2 #8 F 75 160 Left Arthrosis Septic loosening 2.5 3 #9 M 60 170 Right Fracture Septic loosening 1.7 3 #10 F 52 150 Left Valgus deformity Aseptic loosening 1.3 2 #11 M NA NA Left Arthrosis Septic loosening 1.3 3 #12 F 74 153 Right Other Septic loosening 0.4 2 #13 M 95 180 Right Arthrosis Septic loosening 0.5 3 #14 F 107 165 Left Arthrosis Pain without loosening 2.1 4 #15 F 59 155 Right Condyle necrosis Septic loosening 0.1 3 #16 M 70 163 Right Rigidity Rigidity 0.6 3 #17 M 108 182 Right Other Aseptic loosening 4.1 4 #18 M 75 160 Right Fracture Septic loosening 7.6 3 Pz = patient; NA = not available; FU = follow up. Three main roughness indices were considered to characterize the roughness of the specimens: Ra, Rt, and Rsk. The most significant indicator to characterize the surface conditions is the mean roughness, Ra, that represents the amplitude of the arithmetical mean value of the absolute values of the deviations of the real profile compared to the mean profile trace. The peak–peak height Rt is defined as the vertical distance between the highest peak and lowest valley along the measured trace for the whole analyzed surface. The Rsk represents the degree of symmetry of the surface peaks with respect to the mean plane. The values of Rsk may be: a. Equal to zero for a normal distribution; b. Lesser than zero for a negative distribution and a plain profile; c. Greater than zero for a positive distribution and a profile with many peaks. Roughness measurements were performed by means of the contact profilometer Hommel Tester T8000 (Hommel Werke, Luedinghausen, Germany), following an internal and consolidated protocol [17–20] and the following operating parameters: A diamond stylus tip with radius 0.020 mm; A measuring length of 1.5 mm; A cut-off of 0.25 mm; A travel speed of 0.15 mm/s. Appl. Sci. 2021, 11, x FOR PEER REVIEW 3 of 10 #4 F 74 166 Left Aseptic loosening Aseptic loosening 2.1 3 #5 F 78 164 Right Arthrosis Septic loosening 1.0 3 #6 M 106 180 Left Arthrosis Aseptic loosening 1.6 4 #7 M 50 NA Left Post-traumatic arthrosis Septic loosening 0.2 2 #8 F 75 160 Left Arthrosis Septic loosening 2.5 3 #9 M 60 170 Right Fracture Septic loosening 1.7 3 #10 F 52 150 Left Valgus deformity Aseptic loosening 1.3 2 #11 M NA NA Left Arthrosis Septic loosening 1.3 3 #12 F 74 153 Right Other Septic loosening 0.4 2 #13 M 95 180 Right Arthrosis Septic loosening 0.5 3 #14 F 107 165 Left Arthrosis Pain without loosening 2.1 4 #15 F 59 155 Right Condyle necrosis Septic loosening 0.1 3 #16 M 70 163 Right Rigidity Rigidity 0.6 3 #17 M 108 182 Right Other Aseptic loosening 4.1 4 #18 M 75 160 Right Fracture Septic loosening 7.6 3 Pz = patient; NA = not available; FU = follow up. 2.2. Roughness Measurements and 3D Image Generation The wear analysis was performed by means of surface roughness and topographic measurements. All the retrieved specimens were analyzed on three different areas, corresponding to the position of the knee during walk (30° and 60°) or at rest (0°). An area Appl. Sci. 2021, 11, 11224 of interest of 1.5 mm × 1.5 mm (2.25 mm ) was taken into account for ea 4 of ch 10angle and on medial and lateral compartments. Figure 1 shows the measured areas on each prosthesis. Figure 1. Areas on each femoral condyle in which were performed the roughness measurements. Figure 1. Areas on each femoral condyle in which were performed the roughness measurements. All the specimens were prepared following the same procedure: before the roughness Three main roughness indices were considered to characterize the roughness of the measurement, the surfaces were cleaned with acetone and then dried at room temperature specimens: Ra, Rt, and Rsk. The most significant indicator to characterize the surface in a controlled environment. Roughness was detected in A/P (antero/posterior) direction, conditions is the mean roughness, Ra, that represents the amplitude of the arithmetical as it was the main orientation of the scratches. After the roughness measurements, the topographic surface acquisitions were per- formed on the retrievals. Three profiles were considered for each topography measured at 0 , 30 , and 60 and a 3D digital reconstruction of the worn surfaces was performed by calculating the surface topographical parameters by selecting a Gaussian filter M1 (ISO 11562) and a cut-off length of 0.250 mm, according to the recommendations in ISO 4288-1997. The roughness filtration operator allows the mathematical separation of a surface into two new surfaces. The Gauss filtration is used for any undulation or roughness calculation that leads to a precise numerical study. This requirement complies with the recommendations of ISO 11562. Three-dimensional topographical data give information on the wear aggression on the condyle surfaces and, in this study, they are considered as wear maps. In fact, as at the beginning of their exercise, the femoral condyles present a smooth and polished surface with roughness close to zero, the 3D distribution of Ra can be treated as a measure of the worn material, considering that the final surface level coincides with the mean profile. 2.3. Statistical Analysis The resulting roughness values were analyzed using a non-parametric Mann–Whitney (M–W) test. Statistical significance was set at p < 0.05. The analyses were performed comparing the medial versus the lateral roughness measured on each condyle. 3. Results The roughness indicators Ra, Rt, and Rsk were averaged over the repeated measure- ments and tabled in Table 2. Appl. Sci. 2021, 11, 11224 5 of 10 Table 2. Roughness measurements on the femoral knee retrieved components. Pz Ra (m) Rt (m) Rsk (m) Medial Lateral Medial Lateral Medial Lateral 1 0.10  0.00 0.10  0.00 0.71  0.37 0.45  0.13 0.10  0.60 0.07  0.14 2 0.03  0.05 0.02  0.04 0.35  0.08 0.35  0.14 0.33  0.21 0.34  0.51 3 0.10  0.01 0.09  0.04 0.43  0.22 0.45  0.49 0.18  0.70 0.20  0.91 4 0.10  0.00 0.08  0.04 0.49  0.14 0.46  0.18 0.18  0.33 0.03  0.32 5 0.12  0.06 0.08  0.04 0.96  0.70 0.44  0.11 0.07  0.86 0.34  0.40 6 0.10  0.00 0.10  0.00 0.71  0.13 0.67  0.20 0.57  0.39 0.58  0.43 7 0.10  0.01 0.08  0.04 0.38  0.09 0.40  0.11 0.20  0.13 0.27  0.19 8 0.08  0.04 0,08  0.04 0.39  0.10 0.40  0.11 0.24  0.20 0.17  0.18 9 0.10  0.00 0.12  0.05 0.57  0.20 1.10  0.89 0.40  0.48 0.35  0.33 10 0.10  0.00 0.10  0.00 0.72  0.36 0.50  0.14 0.15  0.90 0.19  0.16 11 0.07  0.05 0.06  0.05 0.62  0.66 0.61  0.32 0.06  0.93 0.23  0.65 12 0.10  0.01 0.10  0.00 0.69  0.51 0.60  0.16 0.09  1.12 0.06  0.26 13 0.09  0.03 0.09  0.02 0.48  0.11 0.45  0.13 0.42  0.34 0.41  0.18 14 0.10  0.00 0.10  0.01 0.60  0.48 0.47  0.16 0.05  0.49 0.12  0.23 15 0.10  0.00 0.10  0.00 0.53  0.16 0.47  0.23 0.18  0.19 0.13  0.30 16 0.11  0.03 0.11  0.05 1.10  1.09 0.91  1.57 0.03  1.04 0.30  0.82 17 0.10  0.00 0.10  0.02 0.56  0.15 0.69  0.58 0.25  0.40 0.41  0.75 18 0.10  0.00 0.10  0.00 0.53  0.28 0.65  0.35 0.14  0.66 0.20  1.01 In Figures 2–4, three topographies for each condyle (medial and lateral) are shown. These pictures were obtained as an example of three patients (#pz2, #pz5, #pz16) that showed the minimum, medium, and highest Ra value. In particular, the topography picture, at a glance, represents the cumulative probability density function of the surface profile’s height. Burnishing areas and a pit distribution of approximately 1 mm in size can be found. The 3D images were reconstructed applying the Gaussian filter on the entire surface, with equal cut-off length along the two directions. For patients #2 and #5 (Figures 2 and 3), the medial and lateral compartments showed similar wear behavior: worn surface with scratches mainly oriented along the anterior/posterior (A/P) direction on all the three areas considered for the roughness measurements. Patient #16 (Figure 4) showed less damaged surface on the lateral condyle; thin scratches along the A/P direction are visible on the medial condyle. Regarding the statistical analyses, we found no statistical significance between the medial and lateral condyle for each roughness parameter taken into account. In particular: Ra medial vs. Ra lateral, for each plan (0 , 30 , 60 ) taken into account, showed no statistical significance (p = 0.355); Rt medial vs. Rt lateral, for each plan (0 , 30 , 60 ) taken into account, showed no statistical significance (p = 0.355); Rsk medial vs. Rsk lateral, for each plan (0 , 30 , 60 ) taken into account, showed a statistical significance (p = 0.214). Appl. Sci. 2021, 11, x FOR PEER REVIEW 5 of 10 4 0.10 ± 0.00 0.08 ± 0.04 0.49 ± 0.14 0.46 ± 0.18 0.18 ± 0.33 −0.03 ± 0.32 5 0.12 ± 0.06 0.08 ± 0.04 0.96 ± 0.70 0.44 ± 0.11 −0.07 ± 0.86 0.34 ± 0.40 6 0.10 ± 0.00 0.10 ± 0.00 0.71 ± 0.13 0.67 ± 0.20 0.57 ± 0.39 0.58 ± 0.43 7 0.10 ± 0.01 0.08 ± 0.04 0.38 ± 0.09 0.40 ± 0.11 0.20 ± 0.13 0.27 ± 0.19 8 0.08 ± 0.04 0,08 ± 0.04 0.39 ± 0.10 0.40 ± 0.11 0.24 ± 0.20 0.17 ± 0.18 9 0.10 ± 0.00 0.12 ± 0.05 0.57 ± 0.20 1.10 ± 0.89 0.40 ± 0.48 0.35 ± 0.33 10 0.10 ± 0.00 0.10 ± 0.00 0.72 ± 0.36 0.50 ± 0.14 0.15 ± 0.90 0.19 ± 0.16 11 0.07 ± 0.05 0.06 ± 0.05 0.62 ± 0.66 0.61 ± 0.32 0.06 ± 0.93 0.23 ± 0.65 12 0.10 ± 0.01 0.10 ± 0.00 0.69 ± 0.51 0.60 ± 0.16 0.09 ± 1.12 0.06 ± 0.26 13 0.09 ± 0.03 0.09 ± 0.02 0.48 ± 0.11 0.45 ± 0.13 0.42 ± 0.34 0.41 ± 0.18 14 0.10 ± 0.00 0.10 ± 0.01 0.60 ± 0.48 0.47 ± 0.16 −0.05 ± 0.49 0.12 ± 0.23 15 0.10 ± 0.00 0.10 ± 0.00 0.53 ± 0.16 0.47 ± 0.23 0.18 ± 0.19 0.13 ± 0.30 16 0.11 ± 0.03 0.11 ± 0.05 1.10 ± 1.09 0.91 ± 1.57 0.03 ± 1.04 0.30 ± 0.82 17 0.10 ± 0.00 0.10 ± 0.02 0.56 ± 0.15 0.69 ± 0.58 −0.25 ± 0.40 0.41 ± 0.75 18 0.10 ± 0.00 0.10 ± 0.00 0.53 ± 0.28 0.65 ± 0.35 −0.14 ± 0.66 −0.20 ± 1.01 In Figures 2–4, three topographies for each condyle (medial and lateral) are shown. These pictures were obtained as an example of three patients (#pz2, #pz5, #pz16) that showed the minimum, medium, and highest Ra value. In particular, the topography Appl. Sci. 2021, 11, 11224 6 of 10 picture, at a glance, represents the cumulative probability density function of the surface profile’s height. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 10 Figure 2. Topographical picture of the medial and lateral condyle with the lowest Ra value. Figure 2. Topographical picture of the medial and lateral condyle with the lowest Ra value. Figure Figure 3. 3. Topographical Topographical pictu picture of re of the media the medial and l and lateral lateral co condyle ndyle with the with the medium medium Ra value. Ra value. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 10 Appl. Sci. 2021, 11, 11224 7 of 10 Figure 3. Topographical picture of the medial and lateral condyle with the medium Ra value. Figure 4. Topographical picture of the medial and lateral condyle with the highest Ra value. 4. Discussion TKA is, nowadays, a well-known and widespread surgical procedure. Given the long-term problem of TKA tribological issues, surgeons are more and more interested in studies which improve in vitro tests of implants. Nevertheless, replication of in vivo wear behavior on in vitro tests remains a challenge. In this scenario, the identification of damage patterns and surface roughness distribution evaluation of retrieved components remains a crucial step to enhance the knowledge of tribological phenomena associated to the TKR exercise. In this study, 18 retrieved TKA femoral components were selected choosing the same prosthesis design, but different sizes, to investigate surface characteristics of medial and lateral compartments. Results are given in terms of three roughness parameters (Ra, Rt, Rsk) and of 3D topographical maps of Ra, representing the worn surfaces. Results show a non-uniform wear intensity on the two condyles. This is due to the mechanism of action of misalignments and its effect on load distribution. In fact, a varus knee alignment shifts the load-bearing axis medial to the knee center, creating a moment arm that increases forces across the medial compartment and reduces lateral load. Equally, the lateral shift of the load-bearing axis due to valgus alignment increases forces across the lateral compartment and reduces medial load. In other words, considering a standardized gait, i.e., Figure 5, it is possible to say that the increase in the valgus movement causes a varus compression and this also affects the mode of synovial lubrication of the contact surfaces [21,22]. Appl. Sci. 2021, 11, 11224 8 of 10 Appl. Sci. 2021, 11, x FOR PEER REVIEW 8 of 10 Figure 5. Tibial based TKR reference system. Figure 5. Tibial based TKR reference system. It has been evidenced that surface roughness affects the wear and lubrication It has been evidenced that surface roughness affects the wear and lubrication mecha- mechanism in total artificial joints [23,24]. nism in total artificial joints [23,24]. In this paper, although the cause of the failure was not related to wear, the surface In this paper, although the cause of the failure was not related to wear, the surface analysis was performed to obtain information on the surface damage mode for early analysis was performed to obtain information on the surface damage mode for early implanted inserts to evaluate the early effects of in vivo exercise and provide information implanted inserts to evaluate the early effects of in vivo exercise and provide information to understand. to understand. This article has, obviously, some limitations. The first one is related to the low This article has, obviously, some limitations. The first one is related to the low number number of specimens taken into consideration in this study. The second limitation is the of specimens taken into consideration in this study. The second limitation is the lack of lack of information about measurements performed in different directions than the A/P. information about measurements performed in different directions than the A/P. Further Further studies will be planned considering more specimens with similar characteristics studies will be planned considering more specimens with similar characteristics (i.e., F.U., (i.e., F.U., body mass index, etc.) and to measure the roughness along the medial–lateral body mass index, etc.) and to measure the roughness along the medial–lateral direction at direction at different angles. different angles. Moreover, the measurement of contact surfaces topography plays a key role in the Moreover, the measurement of contact surfaces topography plays a key role in the syn- synovial lubrication regime acting in the artificial joints. In fact, according to Dowson et ovial lubrication regime acting in the artificial joints. In fact, according to Dowson et al. [25], al. [25], the k parameter, calculated as the ratio between the minimum synovial meatus the k parameter, calculated as the ratio between the minimum synovial meatus height and height and the roughness of the surfaces, could assume values lesser than 1, which is the roughness of the surfaces, could assume values lesser than 1, which is characteristic of boundary lubrication phenomena, while for 1 < k < 3, mixed lubrication is expected. Appl. Sci. 2021, 11, 11224 9 of 10 Only in the case of k > 3, a continued film of synovial lubricant is present, which allows the complete separation of the contact surfaces with consequent low wear phenomena. 5. Conclusions This paper presented the roughness characterization and 3D digital topographical representation of significative contact areas of retrieved knee femoral components. The study aimed at studying the wear behavior of 18 selected retrievals on the medial and lateral portions. The 3D topography of the measured surfaces was digitally reconstructed by means of a Gaussian filter, giving evidence of the wear progress over the specimen surfaces. Results show a non-uniform wear intensity on the medial and lateral condyles; however, as already demonstrated in literature, it is not possible to assess if the medial compartments surface are more worn than lateral compartments, or vice versa. Even if in this study the cause of the failure was not related to wear, this paper shows that roughness characterization of TKR early retrieved components applied as a systematic practice will help understand the wear mechanisms and causes and prevent failures due to surface damages. Author Contributions: Conceptualization, S.A. and A.R.; methodology, S.A., A.R. and S.L.; software, S.L.; validation, S.A., A.R., S.L. and M.C.V.; investigation, S.A.; resources, S.A. and A.R.; data curation, S.L.; writing—original draft preparation, S.A.; writing—review and editing, S.A., A.R., S.L. and M.C.V.; supervision, A.R. and M.C.V.; project administration, S.A.; funding acquisition, S.A. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Informed Consent Statement: Ethics approval was not necessary because of features of the registry, collection data as standard practice on all patients in the region, using a format protecting of the identity of the patients. Moreover, the activities of extrapolation and analysis of the RIPO (https://ripo.cineca.it (accessed on 30 September 2021)) are carried out by totally anonymizing all the data in compliance with the current legislation on privacy and confidentiality of users and operators. Data from registry are anonymized following the regional rule of Regione Emilia Romagna as regional means of public health surveillance (law 1_6_17/9). Data Availability Statement: The data present are fully visible on the paper. Acknowledgments: The authors thank Arianna Turchetti (Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA) and Andrea Martelli (IRCCS Istituto Ortopedico Rizzoli) for their help with the set-up and roughness measurements. Conflicts of Interest: The authors declare no conflict of interest. References 1. Drexler, M.; Dwyer, T.; Chakravertty, R.; Farno, A.; Backstein, D. Assuring the happy total knee replacement patient. Bone Jt. J. 2013, 95-B, 120–123. [CrossRef] 2. Rawal, B.; Yadav, A.; Pare, V. Life Estimation of Knee Joint Prosthesis by Combined Effect of Fatigue and Wear. Procedia Technol. 2016, 23, 60–67. [CrossRef] 3. Walker-Santiago, R.; Tegethoff, J.D.; Ralston, W.M.; Keeney, J.A. Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision. J. Arthroplast. 2020, 36, 653–656. [CrossRef] 4. Zanasi, S. Innovations in total knee replacement: New trends in operative treatment and changes in peri-operative management. Eur. Orthop. Traumatol. 2011, 2, 21–31. [CrossRef] [PubMed] 5. Crawford, D.A.; Adams, J.B.; Hobbs, G.R.; Berend, K.R.; Lombardi, A.V. Higher Activity Level Following Total Knee Arthroplasty Is Not Deleterious to Mid-Term Implant Survivorship. J. Arthroplast. 2020, 35, 116–120. [CrossRef] [PubMed] 6. Jenny, J.Y.; Saragaglia, D.; Bercovy, M.; Cazenave, A.; Gaillard, T.; Châtain, F.; Jolles, B.; Rouvillain, J.L. Inconsistent relationship between body weight/body mass index prior to total knee arthroplasty and the 12-year survival. Knee 2019, 26, 1372–1378. [CrossRef] [PubMed] 7. Diabb, J.; Juarez-Hernández, A.; Reyes, A.; Gonzalez-Rivera, C.; Hernandez-Rodriguez, M. Failure analysis for degradation of a polyethylene knee prosthesis component. Eng. Fail. Anal. 2009, 16, 1770–1773. [CrossRef] 8. Postler, A.; Lützner, C.; Beyer, F.; Tille, E.; Lützner, J. Analysis of Total Knee Arthroplasty revision causes. BMC Musculoskelet. Disord. 2018, 19, 55. [CrossRef] 9. Lum, Z.C.; Shieh, A.K.; Dorr, L.D. Why total knees fail-A modern perspective review. World J. Orthop. 2018, 9, 60–64. [CrossRef] Appl. Sci. 2021, 11, 11224 10 of 10 10. Rashed, S.; Lakhani, S.; Mann, A.; Best, L.M.; Shehzad, S.; Saeed, M.Z. Corrigendum to: The Impact of the Largest National Joint Registry on Current Knee Replacement Longevity Estimates: An Analysis and Review of Knee Prosthesis Brand and Fixation Technique. J. Arthroplast. 2021, 36, 3168–3173.e1. [CrossRef] 11. Mathis, D.T.; Lohrer, L.; Amsler, F.; Hirschmann, M.T. Reasons for failure in primary total knee arthroplasty—An analysis of prospectively collected registry data. J. Orthop. 2021, 36, 3168–3173. [CrossRef] [PubMed] 12. Tse, T.S.T.; Wan, Y.-C.S.; Leung, K.-H.L.; Wong, M.-K. Total knee arthroplasty: A single centre review at 10 years of follow-up. J. Orthop. Trauma Rehabil. 2020, 27, 142–147. [CrossRef] 13. Valigi, M.C.; Logozzo, S.; Affatato, S. In Vitro 3D Wear Characterization of Knee Joint Prostheses. In Machine and Machine Science; Springer: Cham, Germany, 2019; pp. 3855–3863. [CrossRef] 14. Affatato, S.; Bracco, P.; Costa, L.; Villa, T.; Quaglini, V.; Toni, A. In vitro wear performance of standard, crosslinked, and vitamin-E-blended UHMWPE. J. Biomed. Mater. Res.—Part A 2012, 100, 554–560. [CrossRef] 15. Affatato, S.; Ruggiero, A. A perspective on biotribology in arthroplasty: From in vitro toward the accurate In Silico wear prediction. Appl. Sci. 2019, 10, 6312. [CrossRef] 16. Affatato, S.; Valigi, M.C.; Logozzo, S. Knee Wear Assessment: 3D Scanners Used as a Consolidated Procedure. Materials 2020, 13, 2349. [CrossRef] [PubMed] 17. Affatato, S.; Grillini, L. Topography in bio-tribocorrosion. In Bio-Tribocorrosion in Biomaterials and Medical Implants; Woodhead Publishing: Cambridge, UK, 2013; pp. 1–21. 18. Abdel-Jaber, S.A.; Ruggiero, A.; Battaglia, S.; Affatato, S. On the Roughness Measurement on Knee Prostheses. Int. J. Artif. Organs 2014, 38, 39–44. [CrossRef] 19. Abdel-Jaber, S.; Belvedere, C.; De Mattia, J.S.; Leardini, A.; Affatato, S. A new protocol for wear testing of total knee prostheses from real joint kinematic data: Towards a scenario of realistic simulations of daily living activities. J. Biomech. 2016, 49, 2925–2931. [CrossRef] 20. Ruggiero, A.; Merola, M.; Affatato, S. On the biotribology of total knee replacement: A new roughness measurements protocol on in vivo condyles considering the dynamic loading from musculoskeletal multibody model. Measurement 2017, 112, 22–28. [CrossRef] 21. Sharma, L.; Song, J.; Dunlop, D.; Felson, D.; Lewis, C.E.; Segal, N.; Torner, J.; Cooke, T.D.V.; Hietpas, J.; Lynch, J.; et al. Varus and valgus alignment and incident and progressive knee osteoarthritis. Ann. Rheum. Dis. 2010, 69, 1940–1945. [CrossRef] 22. Tetsworth, K.; Paley, D. Malalignment and degenerative arthropathy. Orthop. Clin. N. Am. 1994, 25, 367–377. [CrossRef] 23. Welghtman, B.; Light, D. The effect of the surface finish of alumina and stainless steel on the wear rate of UHMW polyethylene. Biomaterials 1986, 7, 20–24. [CrossRef] 24. Cooper, J.R.; Dowson, D.; Fisher, J. The effect of transfer film and surface roughness on the wear of lubricated ultra-high molecular weight polyethylene. Clin. Mater. 1993, 14, 295–302. [CrossRef] 25. Jin, Z.M.; Dowson, D.; Fisher, J. Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus. Proc. Inst. Mech. Eng. Part H J. Eng. Med. 1997, 211, 247–256. [CrossRef] [PubMed] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Sciences Multidisciplinary Digital Publishing Institute

Roughness Digital Characterization and Influence on Wear of Retrieved Knee Components

Loading next page...
 
/lp/multidisciplinary-digital-publishing-institute/roughness-digital-characterization-and-influence-on-wear-of-retrieved-p0aM96Hs8Q
Publisher
Multidisciplinary Digital Publishing Institute
Copyright
© 1996-2021 MDPI (Basel, Switzerland) unless otherwise stated Disclaimer The statements, opinions and data contained in the journals are solely those of the individual authors and contributors and not of the publisher and the editor(s). MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Terms and Conditions Privacy Policy
ISSN
2076-3417
DOI
10.3390/app112311224
Publisher site
See Article on Publisher Site

Abstract

applied sciences Article Roughness Digital Characterization and Influence on Wear of Retrieved Knee Components 1 , 2 3 3 Saverio Affatato * , Alessandro Ruggiero , Silvia Logozzo and Maria Cristina Valigi Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, nr. 132, 84084 Fisciano, Italy; ruggiero@unisa.it Department of Engineering, University of Perugia, Via Goffredo Duranti, 93, 06125 Perugia, Italy; silvia.logozzo@unipg.it (S.L.); mariacristina.valigi@unipg.it (M.C.V.) * Correspondence: affatato@tecno.ior.it Featured Application: This paper is focused on the roughness of lateral and medial condyles used to digitally reconstruct the 3D topography of surfaces, giving insights about the wear behavior. Abstract: Tribological performance of knee components are strongly related to the surface character- istics. Primarily, the roughness and its 3D distribution on the surfaces affect the joint performance. One of the main limitations related to the tribological study of knee prostheses is that most of the research studies report in vitro or in silico results, as knee retrievals are difficult to find or are too damaged to be analyzed. This paper is focused on the roughness characterization of retrieved metal femoral components of total knee replacements (TKR) by means of a rugosimeter and involving digital methods to reconstruct the 3D topography of the studied surfaces. The aim of this study is to Citation: Affatato, S.; Ruggiero, A.; investigate how changes and distribution of roughness are correlated between the medial vs. the Logozzo, S.; Valigi, M.C. Roughness lateral part and how the resulting digital topography can give insights about the wear behavior. Digital Characterization and Influence on Wear of Retrieved Knee Keywords: total knee arthroplasty; digital biotribology; 3D topography; roughness characterization; Components. Appl. Sci. 2021, 11, wear maps 11224. https://doi.org/10.3390/ app112311224 Academic Editor: Alessandro Gasparetto 1. Introduction Total knee replacement (TKR) is an elective surgical procedure in orthopedic surgery Received: 11 October 2021 worldwide to relieve pain in patients with osteoarthritis and to improve function and Accepted: 23 November 2021 restore a good quality of life for patients [1]. In general, TKR consists of three main Published: 26 November 2021 components: a metal femoral part, a metal tibial plate, and a polyethylene tibial insert. A knee replacement may fail over time and may need a second surgery for a variety of issues. Publisher’s Note: MDPI stays neutral Evidence from previous studies demonstrates that a TKR can last, at most, 15–20 years [2]. with regard to jurisdictional claims in It is known that the success and longevity of a knee implant is affected by the characteristics published maps and institutional affil- of patients such as age, weight, gender, and activity level [3–6]. Surface damage and wear iations. are the main threats to the long-term survival of a TKR [7,8]. Failure most commonly occurs due to fatigue and adhesive wear, which are responsible for the generation of micro particulate debris that, in turn, cause osteolysis around the replacements, ultimately leading to loosening and failure of the TKR [7–9]. The survival rate of total knee replacements Copyright: © 2021 by the authors. (TKR) has been reported to increase along with the development of advanced technologies Licensee MDPI, Basel, Switzerland. and operative techniques [10–12]. This article is an open access article Tribological aspects of knee components are strongly related to the surface conditions. distributed under the terms and For instance, the 3D distribution of roughness and the surface topography affect the joint conditions of the Creative Commons effectiveness. Many tribological studies regarding knee implants were performed in vitro Attribution (CC BY) license (https:// or in silico conditions [13–16], as knee retrievals are difficult to find or are too damaged to creativecommons.org/licenses/by/ be analyzed. 4.0/). Appl. Sci. 2021, 11, 11224. https://doi.org/10.3390/app112311224 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 11224 2 of 10 In the case of in vitro studies, the femoral or tibial inserts undergo wearing cycles at dedicated simulators in laboratory conditions, trying to replicate general motion activities, whereas in silico studies involve computational analyses of knee virtual models. In vitro and in silico tribo-characterization of prostheses are surely useful but they are rarely as predictive as in vivo studies. Nevertheless, the advantage of in vitro and in silico analyses is that all the phenomena are repeatable. This study reports relevant damage mechanisms seen in retrieved metallic femoral components of total knee replacements accompanied with failure. Retrieved knee implants were obtained from the Register of Explant of Orthopedic Prostheses (REPO, IRCCS Is- tituto Ortopedico Rizzoli). To limit the effects of the prosthetic design on the roughness measurements, 18 prostheses of the same prosthetic model were selected to minimize pos- sible confounding factors. Although most of the implants were removed due to infection, the surface analysis was essential to analyze the surface damage mode of a short-term implants. The aim of this paper is to perform a roughness characterization of the retrieved components to evaluate how changes and distribution of roughness are correlated between the medial vs. the lateral part and how the resulting digital topography can give insights about the wear behavior. The qualitative description of the severity and location of surface damage can explain the damage mechanism on the early-retrieved implants. The surface characterization was performed using a Hommel Werke rugosimeter to evaluate the surface roughness and the texture of these components in different locations over the lateral and medial areas. The rugosimeter allowed to acquire the target surfaces point by point. In addition, a Gaussian filter was involved as a digital method to reconstruct the 3D topography of the studied surfaces, which can be read as a 3D wear map, in terms of qualitative distribution considering the strict correlation with the roughness. 2. Materials and Methods 2.1. Process of Selection The sample implants were selected from REPO (Register of Explants of Orthopedic Prosthesis) which collects and categorizes medical devices explanted at the IRCCS Rizzoli Orthopaedic Institute (IOR). Starting from about 186 knee prosthesis explants, the largest group of prostheses with the same model was chosen by two independent observers (AM and AT) to keep a low variability and to limit the effects of the prosthetic design on the roughness measurements. Moreover, only the prostheses with particular evidence of scratches, pitting, or evident metal transfer were chosen for the analyses as the other ones were not significantly worn. In the end, 18 metallic femoral knee prostheses of the NexGen- LPS-Flex Fixed-Zimmer model, which were implanted from 2006 to 2016, remained for the roughness characterization. This kind of implant is a posterior stabilized prosthesis designed to accommodate a greater range of motion for appropriate patients. In this fixed configuration, the metallic tibial component is fixed to the tibial bone while the menisci are press-fit on the tibial plate. Major details about the sample condyles are given in Table 1. 2.2. Roughness Measurements and 3D Image Generation The wear analysis was performed by means of surface roughness and topographic measurements. All the retrieved specimens were analyzed on three different areas, cor- responding to the position of the knee during walk (30 and 60 ) or at rest (0 ). An area of interest of 1.5 mm  1.5 mm (2.25 mm ) was taken into account for each angle and on medial and lateral compartments. Figure 1 shows the measured areas on each prosthesis. Appl. Sci. 2021, 11, 11224 3 of 10 Table 1. Specimen selection, patient characteristics, follow up, and prosthesis size-number. Pz Gender Weight (kg) Height (cm) Side Diagnosis Reason for Revision F.U. (Years) Size #1 F 80 160 Right Fracture Septic loosening 1.5 3 #2 M 94 170 Left Unknown Septic loosening 0.7 3 #3 M 71 170 Right Other Aseptic loosening 2.5 3 #4 F 74 166 Left Aseptic loosening Aseptic loosening 2.1 3 #5 F 78 164 Right Arthrosis Septic loosening 1.0 3 #6 M 106 180 Left Arthrosis Aseptic loosening 1.6 4 #7 M 50 NA Left Post-traumatic arthrosis Septic loosening 0.2 2 #8 F 75 160 Left Arthrosis Septic loosening 2.5 3 #9 M 60 170 Right Fracture Septic loosening 1.7 3 #10 F 52 150 Left Valgus deformity Aseptic loosening 1.3 2 #11 M NA NA Left Arthrosis Septic loosening 1.3 3 #12 F 74 153 Right Other Septic loosening 0.4 2 #13 M 95 180 Right Arthrosis Septic loosening 0.5 3 #14 F 107 165 Left Arthrosis Pain without loosening 2.1 4 #15 F 59 155 Right Condyle necrosis Septic loosening 0.1 3 #16 M 70 163 Right Rigidity Rigidity 0.6 3 #17 M 108 182 Right Other Aseptic loosening 4.1 4 #18 M 75 160 Right Fracture Septic loosening 7.6 3 Pz = patient; NA = not available; FU = follow up. Three main roughness indices were considered to characterize the roughness of the specimens: Ra, Rt, and Rsk. The most significant indicator to characterize the surface conditions is the mean roughness, Ra, that represents the amplitude of the arithmetical mean value of the absolute values of the deviations of the real profile compared to the mean profile trace. The peak–peak height Rt is defined as the vertical distance between the highest peak and lowest valley along the measured trace for the whole analyzed surface. The Rsk represents the degree of symmetry of the surface peaks with respect to the mean plane. The values of Rsk may be: a. Equal to zero for a normal distribution; b. Lesser than zero for a negative distribution and a plain profile; c. Greater than zero for a positive distribution and a profile with many peaks. Roughness measurements were performed by means of the contact profilometer Hommel Tester T8000 (Hommel Werke, Luedinghausen, Germany), following an internal and consolidated protocol [17–20] and the following operating parameters: A diamond stylus tip with radius 0.020 mm; A measuring length of 1.5 mm; A cut-off of 0.25 mm; A travel speed of 0.15 mm/s. Appl. Sci. 2021, 11, x FOR PEER REVIEW 3 of 10 #4 F 74 166 Left Aseptic loosening Aseptic loosening 2.1 3 #5 F 78 164 Right Arthrosis Septic loosening 1.0 3 #6 M 106 180 Left Arthrosis Aseptic loosening 1.6 4 #7 M 50 NA Left Post-traumatic arthrosis Septic loosening 0.2 2 #8 F 75 160 Left Arthrosis Septic loosening 2.5 3 #9 M 60 170 Right Fracture Septic loosening 1.7 3 #10 F 52 150 Left Valgus deformity Aseptic loosening 1.3 2 #11 M NA NA Left Arthrosis Septic loosening 1.3 3 #12 F 74 153 Right Other Septic loosening 0.4 2 #13 M 95 180 Right Arthrosis Septic loosening 0.5 3 #14 F 107 165 Left Arthrosis Pain without loosening 2.1 4 #15 F 59 155 Right Condyle necrosis Septic loosening 0.1 3 #16 M 70 163 Right Rigidity Rigidity 0.6 3 #17 M 108 182 Right Other Aseptic loosening 4.1 4 #18 M 75 160 Right Fracture Septic loosening 7.6 3 Pz = patient; NA = not available; FU = follow up. 2.2. Roughness Measurements and 3D Image Generation The wear analysis was performed by means of surface roughness and topographic measurements. All the retrieved specimens were analyzed on three different areas, corresponding to the position of the knee during walk (30° and 60°) or at rest (0°). An area Appl. Sci. 2021, 11, 11224 of interest of 1.5 mm × 1.5 mm (2.25 mm ) was taken into account for ea 4 of ch 10angle and on medial and lateral compartments. Figure 1 shows the measured areas on each prosthesis. Figure 1. Areas on each femoral condyle in which were performed the roughness measurements. Figure 1. Areas on each femoral condyle in which were performed the roughness measurements. All the specimens were prepared following the same procedure: before the roughness Three main roughness indices were considered to characterize the roughness of the measurement, the surfaces were cleaned with acetone and then dried at room temperature specimens: Ra, Rt, and Rsk. The most significant indicator to characterize the surface in a controlled environment. Roughness was detected in A/P (antero/posterior) direction, conditions is the mean roughness, Ra, that represents the amplitude of the arithmetical as it was the main orientation of the scratches. After the roughness measurements, the topographic surface acquisitions were per- formed on the retrievals. Three profiles were considered for each topography measured at 0 , 30 , and 60 and a 3D digital reconstruction of the worn surfaces was performed by calculating the surface topographical parameters by selecting a Gaussian filter M1 (ISO 11562) and a cut-off length of 0.250 mm, according to the recommendations in ISO 4288-1997. The roughness filtration operator allows the mathematical separation of a surface into two new surfaces. The Gauss filtration is used for any undulation or roughness calculation that leads to a precise numerical study. This requirement complies with the recommendations of ISO 11562. Three-dimensional topographical data give information on the wear aggression on the condyle surfaces and, in this study, they are considered as wear maps. In fact, as at the beginning of their exercise, the femoral condyles present a smooth and polished surface with roughness close to zero, the 3D distribution of Ra can be treated as a measure of the worn material, considering that the final surface level coincides with the mean profile. 2.3. Statistical Analysis The resulting roughness values were analyzed using a non-parametric Mann–Whitney (M–W) test. Statistical significance was set at p < 0.05. The analyses were performed comparing the medial versus the lateral roughness measured on each condyle. 3. Results The roughness indicators Ra, Rt, and Rsk were averaged over the repeated measure- ments and tabled in Table 2. Appl. Sci. 2021, 11, 11224 5 of 10 Table 2. Roughness measurements on the femoral knee retrieved components. Pz Ra (m) Rt (m) Rsk (m) Medial Lateral Medial Lateral Medial Lateral 1 0.10  0.00 0.10  0.00 0.71  0.37 0.45  0.13 0.10  0.60 0.07  0.14 2 0.03  0.05 0.02  0.04 0.35  0.08 0.35  0.14 0.33  0.21 0.34  0.51 3 0.10  0.01 0.09  0.04 0.43  0.22 0.45  0.49 0.18  0.70 0.20  0.91 4 0.10  0.00 0.08  0.04 0.49  0.14 0.46  0.18 0.18  0.33 0.03  0.32 5 0.12  0.06 0.08  0.04 0.96  0.70 0.44  0.11 0.07  0.86 0.34  0.40 6 0.10  0.00 0.10  0.00 0.71  0.13 0.67  0.20 0.57  0.39 0.58  0.43 7 0.10  0.01 0.08  0.04 0.38  0.09 0.40  0.11 0.20  0.13 0.27  0.19 8 0.08  0.04 0,08  0.04 0.39  0.10 0.40  0.11 0.24  0.20 0.17  0.18 9 0.10  0.00 0.12  0.05 0.57  0.20 1.10  0.89 0.40  0.48 0.35  0.33 10 0.10  0.00 0.10  0.00 0.72  0.36 0.50  0.14 0.15  0.90 0.19  0.16 11 0.07  0.05 0.06  0.05 0.62  0.66 0.61  0.32 0.06  0.93 0.23  0.65 12 0.10  0.01 0.10  0.00 0.69  0.51 0.60  0.16 0.09  1.12 0.06  0.26 13 0.09  0.03 0.09  0.02 0.48  0.11 0.45  0.13 0.42  0.34 0.41  0.18 14 0.10  0.00 0.10  0.01 0.60  0.48 0.47  0.16 0.05  0.49 0.12  0.23 15 0.10  0.00 0.10  0.00 0.53  0.16 0.47  0.23 0.18  0.19 0.13  0.30 16 0.11  0.03 0.11  0.05 1.10  1.09 0.91  1.57 0.03  1.04 0.30  0.82 17 0.10  0.00 0.10  0.02 0.56  0.15 0.69  0.58 0.25  0.40 0.41  0.75 18 0.10  0.00 0.10  0.00 0.53  0.28 0.65  0.35 0.14  0.66 0.20  1.01 In Figures 2–4, three topographies for each condyle (medial and lateral) are shown. These pictures were obtained as an example of three patients (#pz2, #pz5, #pz16) that showed the minimum, medium, and highest Ra value. In particular, the topography picture, at a glance, represents the cumulative probability density function of the surface profile’s height. Burnishing areas and a pit distribution of approximately 1 mm in size can be found. The 3D images were reconstructed applying the Gaussian filter on the entire surface, with equal cut-off length along the two directions. For patients #2 and #5 (Figures 2 and 3), the medial and lateral compartments showed similar wear behavior: worn surface with scratches mainly oriented along the anterior/posterior (A/P) direction on all the three areas considered for the roughness measurements. Patient #16 (Figure 4) showed less damaged surface on the lateral condyle; thin scratches along the A/P direction are visible on the medial condyle. Regarding the statistical analyses, we found no statistical significance between the medial and lateral condyle for each roughness parameter taken into account. In particular: Ra medial vs. Ra lateral, for each plan (0 , 30 , 60 ) taken into account, showed no statistical significance (p = 0.355); Rt medial vs. Rt lateral, for each plan (0 , 30 , 60 ) taken into account, showed no statistical significance (p = 0.355); Rsk medial vs. Rsk lateral, for each plan (0 , 30 , 60 ) taken into account, showed a statistical significance (p = 0.214). Appl. Sci. 2021, 11, x FOR PEER REVIEW 5 of 10 4 0.10 ± 0.00 0.08 ± 0.04 0.49 ± 0.14 0.46 ± 0.18 0.18 ± 0.33 −0.03 ± 0.32 5 0.12 ± 0.06 0.08 ± 0.04 0.96 ± 0.70 0.44 ± 0.11 −0.07 ± 0.86 0.34 ± 0.40 6 0.10 ± 0.00 0.10 ± 0.00 0.71 ± 0.13 0.67 ± 0.20 0.57 ± 0.39 0.58 ± 0.43 7 0.10 ± 0.01 0.08 ± 0.04 0.38 ± 0.09 0.40 ± 0.11 0.20 ± 0.13 0.27 ± 0.19 8 0.08 ± 0.04 0,08 ± 0.04 0.39 ± 0.10 0.40 ± 0.11 0.24 ± 0.20 0.17 ± 0.18 9 0.10 ± 0.00 0.12 ± 0.05 0.57 ± 0.20 1.10 ± 0.89 0.40 ± 0.48 0.35 ± 0.33 10 0.10 ± 0.00 0.10 ± 0.00 0.72 ± 0.36 0.50 ± 0.14 0.15 ± 0.90 0.19 ± 0.16 11 0.07 ± 0.05 0.06 ± 0.05 0.62 ± 0.66 0.61 ± 0.32 0.06 ± 0.93 0.23 ± 0.65 12 0.10 ± 0.01 0.10 ± 0.00 0.69 ± 0.51 0.60 ± 0.16 0.09 ± 1.12 0.06 ± 0.26 13 0.09 ± 0.03 0.09 ± 0.02 0.48 ± 0.11 0.45 ± 0.13 0.42 ± 0.34 0.41 ± 0.18 14 0.10 ± 0.00 0.10 ± 0.01 0.60 ± 0.48 0.47 ± 0.16 −0.05 ± 0.49 0.12 ± 0.23 15 0.10 ± 0.00 0.10 ± 0.00 0.53 ± 0.16 0.47 ± 0.23 0.18 ± 0.19 0.13 ± 0.30 16 0.11 ± 0.03 0.11 ± 0.05 1.10 ± 1.09 0.91 ± 1.57 0.03 ± 1.04 0.30 ± 0.82 17 0.10 ± 0.00 0.10 ± 0.02 0.56 ± 0.15 0.69 ± 0.58 −0.25 ± 0.40 0.41 ± 0.75 18 0.10 ± 0.00 0.10 ± 0.00 0.53 ± 0.28 0.65 ± 0.35 −0.14 ± 0.66 −0.20 ± 1.01 In Figures 2–4, three topographies for each condyle (medial and lateral) are shown. These pictures were obtained as an example of three patients (#pz2, #pz5, #pz16) that showed the minimum, medium, and highest Ra value. In particular, the topography Appl. Sci. 2021, 11, 11224 6 of 10 picture, at a glance, represents the cumulative probability density function of the surface profile’s height. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 10 Figure 2. Topographical picture of the medial and lateral condyle with the lowest Ra value. Figure 2. Topographical picture of the medial and lateral condyle with the lowest Ra value. Figure Figure 3. 3. Topographical Topographical pictu picture of re of the media the medial and l and lateral lateral co condyle ndyle with the with the medium medium Ra value. Ra value. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 10 Appl. Sci. 2021, 11, 11224 7 of 10 Figure 3. Topographical picture of the medial and lateral condyle with the medium Ra value. Figure 4. Topographical picture of the medial and lateral condyle with the highest Ra value. 4. Discussion TKA is, nowadays, a well-known and widespread surgical procedure. Given the long-term problem of TKA tribological issues, surgeons are more and more interested in studies which improve in vitro tests of implants. Nevertheless, replication of in vivo wear behavior on in vitro tests remains a challenge. In this scenario, the identification of damage patterns and surface roughness distribution evaluation of retrieved components remains a crucial step to enhance the knowledge of tribological phenomena associated to the TKR exercise. In this study, 18 retrieved TKA femoral components were selected choosing the same prosthesis design, but different sizes, to investigate surface characteristics of medial and lateral compartments. Results are given in terms of three roughness parameters (Ra, Rt, Rsk) and of 3D topographical maps of Ra, representing the worn surfaces. Results show a non-uniform wear intensity on the two condyles. This is due to the mechanism of action of misalignments and its effect on load distribution. In fact, a varus knee alignment shifts the load-bearing axis medial to the knee center, creating a moment arm that increases forces across the medial compartment and reduces lateral load. Equally, the lateral shift of the load-bearing axis due to valgus alignment increases forces across the lateral compartment and reduces medial load. In other words, considering a standardized gait, i.e., Figure 5, it is possible to say that the increase in the valgus movement causes a varus compression and this also affects the mode of synovial lubrication of the contact surfaces [21,22]. Appl. Sci. 2021, 11, 11224 8 of 10 Appl. Sci. 2021, 11, x FOR PEER REVIEW 8 of 10 Figure 5. Tibial based TKR reference system. Figure 5. Tibial based TKR reference system. It has been evidenced that surface roughness affects the wear and lubrication It has been evidenced that surface roughness affects the wear and lubrication mecha- mechanism in total artificial joints [23,24]. nism in total artificial joints [23,24]. In this paper, although the cause of the failure was not related to wear, the surface In this paper, although the cause of the failure was not related to wear, the surface analysis was performed to obtain information on the surface damage mode for early analysis was performed to obtain information on the surface damage mode for early implanted inserts to evaluate the early effects of in vivo exercise and provide information implanted inserts to evaluate the early effects of in vivo exercise and provide information to understand. to understand. This article has, obviously, some limitations. The first one is related to the low This article has, obviously, some limitations. The first one is related to the low number number of specimens taken into consideration in this study. The second limitation is the of specimens taken into consideration in this study. The second limitation is the lack of lack of information about measurements performed in different directions than the A/P. information about measurements performed in different directions than the A/P. Further Further studies will be planned considering more specimens with similar characteristics studies will be planned considering more specimens with similar characteristics (i.e., F.U., (i.e., F.U., body mass index, etc.) and to measure the roughness along the medial–lateral body mass index, etc.) and to measure the roughness along the medial–lateral direction at direction at different angles. different angles. Moreover, the measurement of contact surfaces topography plays a key role in the Moreover, the measurement of contact surfaces topography plays a key role in the syn- synovial lubrication regime acting in the artificial joints. In fact, according to Dowson et ovial lubrication regime acting in the artificial joints. In fact, according to Dowson et al. [25], al. [25], the k parameter, calculated as the ratio between the minimum synovial meatus the k parameter, calculated as the ratio between the minimum synovial meatus height and height and the roughness of the surfaces, could assume values lesser than 1, which is the roughness of the surfaces, could assume values lesser than 1, which is characteristic of boundary lubrication phenomena, while for 1 < k < 3, mixed lubrication is expected. Appl. Sci. 2021, 11, 11224 9 of 10 Only in the case of k > 3, a continued film of synovial lubricant is present, which allows the complete separation of the contact surfaces with consequent low wear phenomena. 5. Conclusions This paper presented the roughness characterization and 3D digital topographical representation of significative contact areas of retrieved knee femoral components. The study aimed at studying the wear behavior of 18 selected retrievals on the medial and lateral portions. The 3D topography of the measured surfaces was digitally reconstructed by means of a Gaussian filter, giving evidence of the wear progress over the specimen surfaces. Results show a non-uniform wear intensity on the medial and lateral condyles; however, as already demonstrated in literature, it is not possible to assess if the medial compartments surface are more worn than lateral compartments, or vice versa. Even if in this study the cause of the failure was not related to wear, this paper shows that roughness characterization of TKR early retrieved components applied as a systematic practice will help understand the wear mechanisms and causes and prevent failures due to surface damages. Author Contributions: Conceptualization, S.A. and A.R.; methodology, S.A., A.R. and S.L.; software, S.L.; validation, S.A., A.R., S.L. and M.C.V.; investigation, S.A.; resources, S.A. and A.R.; data curation, S.L.; writing—original draft preparation, S.A.; writing—review and editing, S.A., A.R., S.L. and M.C.V.; supervision, A.R. and M.C.V.; project administration, S.A.; funding acquisition, S.A. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Informed Consent Statement: Ethics approval was not necessary because of features of the registry, collection data as standard practice on all patients in the region, using a format protecting of the identity of the patients. Moreover, the activities of extrapolation and analysis of the RIPO (https://ripo.cineca.it (accessed on 30 September 2021)) are carried out by totally anonymizing all the data in compliance with the current legislation on privacy and confidentiality of users and operators. Data from registry are anonymized following the regional rule of Regione Emilia Romagna as regional means of public health surveillance (law 1_6_17/9). Data Availability Statement: The data present are fully visible on the paper. Acknowledgments: The authors thank Arianna Turchetti (Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA) and Andrea Martelli (IRCCS Istituto Ortopedico Rizzoli) for their help with the set-up and roughness measurements. Conflicts of Interest: The authors declare no conflict of interest. References 1. Drexler, M.; Dwyer, T.; Chakravertty, R.; Farno, A.; Backstein, D. Assuring the happy total knee replacement patient. Bone Jt. J. 2013, 95-B, 120–123. [CrossRef] 2. Rawal, B.; Yadav, A.; Pare, V. Life Estimation of Knee Joint Prosthesis by Combined Effect of Fatigue and Wear. Procedia Technol. 2016, 23, 60–67. [CrossRef] 3. Walker-Santiago, R.; Tegethoff, J.D.; Ralston, W.M.; Keeney, J.A. Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision. J. Arthroplast. 2020, 36, 653–656. [CrossRef] 4. Zanasi, S. Innovations in total knee replacement: New trends in operative treatment and changes in peri-operative management. Eur. Orthop. Traumatol. 2011, 2, 21–31. [CrossRef] [PubMed] 5. Crawford, D.A.; Adams, J.B.; Hobbs, G.R.; Berend, K.R.; Lombardi, A.V. Higher Activity Level Following Total Knee Arthroplasty Is Not Deleterious to Mid-Term Implant Survivorship. J. Arthroplast. 2020, 35, 116–120. [CrossRef] [PubMed] 6. Jenny, J.Y.; Saragaglia, D.; Bercovy, M.; Cazenave, A.; Gaillard, T.; Châtain, F.; Jolles, B.; Rouvillain, J.L. Inconsistent relationship between body weight/body mass index prior to total knee arthroplasty and the 12-year survival. Knee 2019, 26, 1372–1378. [CrossRef] [PubMed] 7. Diabb, J.; Juarez-Hernández, A.; Reyes, A.; Gonzalez-Rivera, C.; Hernandez-Rodriguez, M. Failure analysis for degradation of a polyethylene knee prosthesis component. Eng. Fail. Anal. 2009, 16, 1770–1773. [CrossRef] 8. Postler, A.; Lützner, C.; Beyer, F.; Tille, E.; Lützner, J. Analysis of Total Knee Arthroplasty revision causes. BMC Musculoskelet. Disord. 2018, 19, 55. [CrossRef] 9. Lum, Z.C.; Shieh, A.K.; Dorr, L.D. Why total knees fail-A modern perspective review. World J. Orthop. 2018, 9, 60–64. [CrossRef] Appl. Sci. 2021, 11, 11224 10 of 10 10. Rashed, S.; Lakhani, S.; Mann, A.; Best, L.M.; Shehzad, S.; Saeed, M.Z. Corrigendum to: The Impact of the Largest National Joint Registry on Current Knee Replacement Longevity Estimates: An Analysis and Review of Knee Prosthesis Brand and Fixation Technique. J. Arthroplast. 2021, 36, 3168–3173.e1. [CrossRef] 11. Mathis, D.T.; Lohrer, L.; Amsler, F.; Hirschmann, M.T. Reasons for failure in primary total knee arthroplasty—An analysis of prospectively collected registry data. J. Orthop. 2021, 36, 3168–3173. [CrossRef] [PubMed] 12. Tse, T.S.T.; Wan, Y.-C.S.; Leung, K.-H.L.; Wong, M.-K. Total knee arthroplasty: A single centre review at 10 years of follow-up. J. Orthop. Trauma Rehabil. 2020, 27, 142–147. [CrossRef] 13. Valigi, M.C.; Logozzo, S.; Affatato, S. In Vitro 3D Wear Characterization of Knee Joint Prostheses. In Machine and Machine Science; Springer: Cham, Germany, 2019; pp. 3855–3863. [CrossRef] 14. Affatato, S.; Bracco, P.; Costa, L.; Villa, T.; Quaglini, V.; Toni, A. In vitro wear performance of standard, crosslinked, and vitamin-E-blended UHMWPE. J. Biomed. Mater. Res.—Part A 2012, 100, 554–560. [CrossRef] 15. Affatato, S.; Ruggiero, A. A perspective on biotribology in arthroplasty: From in vitro toward the accurate In Silico wear prediction. Appl. Sci. 2019, 10, 6312. [CrossRef] 16. Affatato, S.; Valigi, M.C.; Logozzo, S. Knee Wear Assessment: 3D Scanners Used as a Consolidated Procedure. Materials 2020, 13, 2349. [CrossRef] [PubMed] 17. Affatato, S.; Grillini, L. Topography in bio-tribocorrosion. In Bio-Tribocorrosion in Biomaterials and Medical Implants; Woodhead Publishing: Cambridge, UK, 2013; pp. 1–21. 18. Abdel-Jaber, S.A.; Ruggiero, A.; Battaglia, S.; Affatato, S. On the Roughness Measurement on Knee Prostheses. Int. J. Artif. Organs 2014, 38, 39–44. [CrossRef] 19. Abdel-Jaber, S.; Belvedere, C.; De Mattia, J.S.; Leardini, A.; Affatato, S. A new protocol for wear testing of total knee prostheses from real joint kinematic data: Towards a scenario of realistic simulations of daily living activities. J. Biomech. 2016, 49, 2925–2931. [CrossRef] 20. Ruggiero, A.; Merola, M.; Affatato, S. On the biotribology of total knee replacement: A new roughness measurements protocol on in vivo condyles considering the dynamic loading from musculoskeletal multibody model. Measurement 2017, 112, 22–28. [CrossRef] 21. Sharma, L.; Song, J.; Dunlop, D.; Felson, D.; Lewis, C.E.; Segal, N.; Torner, J.; Cooke, T.D.V.; Hietpas, J.; Lynch, J.; et al. Varus and valgus alignment and incident and progressive knee osteoarthritis. Ann. Rheum. Dis. 2010, 69, 1940–1945. [CrossRef] 22. Tetsworth, K.; Paley, D. Malalignment and degenerative arthropathy. Orthop. Clin. N. Am. 1994, 25, 367–377. [CrossRef] 23. Welghtman, B.; Light, D. The effect of the surface finish of alumina and stainless steel on the wear rate of UHMW polyethylene. Biomaterials 1986, 7, 20–24. [CrossRef] 24. Cooper, J.R.; Dowson, D.; Fisher, J. The effect of transfer film and surface roughness on the wear of lubricated ultra-high molecular weight polyethylene. Clin. Mater. 1993, 14, 295–302. [CrossRef] 25. Jin, Z.M.; Dowson, D.; Fisher, J. Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus. Proc. Inst. Mech. Eng. Part H J. Eng. Med. 1997, 211, 247–256. [CrossRef] [PubMed]

Journal

Applied SciencesMultidisciplinary Digital Publishing Institute

Published: Nov 26, 2021

Keywords: total knee arthroplasty; digital biotribology; 3D topography; roughness characterization; wear maps

There are no references for this article.