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Cho HS, Hong HT, Kwon HM, Koh YG, Hwang SM, Park KK, Kang KT. Influence of Patellar Implant Shape on Patellofemoral Contact Pressure Using Finite Element Analysis. Yonsei Med J 2025; 66:383-389. [PMID: 40414830 PMCID: PMC12116871 DOI: 10.3349/ymj.2024.0283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2024] [Revised: 10/18/2024] [Accepted: 10/28/2024] [Indexed: 05/27/2025] Open
Abstract
PURPOSE This study focused on analyzing the contact pressure and area on different patellar component designs in total knee arthroplasty (TKA) to evaluate biomechanics related to the patellofemoral (PF) joint. MATERIALS AND METHODS The patellar components studied included the dome design, modified dome design, and anatomical design implants. Using finite element analysis and mechanical testing, the pressure and area were evaluated. The first loading condition was simulated at flexion angles of 0°, 15°, 45°, 90°, 120°, and 150°. The second loading condition was simulated for a clinically relevant scenario, involving a 2-mm medial shift at a flexion angle of 45°. RESULTS For both the modified dome and anatomical designs, the contact area and pressure increased with the flexion angle. The dome design reached its maximum contact area at a flexion angle of 120°. Among the designs, the anatomical design had the largest contact area and a lower contact pressure compared to the dome and modified dome designs. However, when a medial shift of 2 mm was simulated at a 45° flexion angle, which can occur clinically, the anatomical design showed edge contact, leading to higher contact pressure and reduced contact area. In contrast, the modified dome design demonstrated the lowest contact pressure and the greatest contact area under the same shifted conditions. CONCLUSION These findings suggest that the design of the patellar component significantly affects patellar biomechanics and stability. Specifically, the modified dome design showed improved biomechanical effects in clinically relevant scenarios. Therefore, patellar components with a modified dome design are expected to better manage PF joint pain and reduce complications in TKA.
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Affiliation(s)
- Hun Sik Cho
- Department of Orthopedic Surgery, Yonsei University College of Medicine, Seoul, Korea
- Department of Orthopedic Surgery, Asan Reconstructive Hospital, Yangju, Korea
| | | | - Hyuck Min Kwon
- Department of Orthopedic Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Yong-Gon Koh
- Joint Reconstruction Center, Department of Orthopaedic Surgery, Yonsei Sarang Hospital, Seoul, Korea
| | - Seong-Mun Hwang
- Department of Orthopedic Surgery, Asan Reconstructive Hospital, Yangju, Korea
| | - Kwan Kyu Park
- Department of Orthopedic Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
| | - Kyoung-Tak Kang
- Skyve R&D LAB, Seoul, Korea
- Department of Mechanical Engineering, Yonsei University, Seoul, Korea.
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Hajiaghajani S, Bahrami O, Hefzosseheh M, Alaei M, Mehrvar A, Poursalehian M. "Anatomic patella design versus medialized dome design in the modern posterior stabilized (ATTUNE) total knee arthroplasty: a systematic review and meta-analysis". J Orthop Surg Res 2025; 20:442. [PMID: 40319293 PMCID: PMC12049006 DOI: 10.1186/s13018-025-05858-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2025] [Accepted: 04/24/2025] [Indexed: 05/07/2025] Open
Abstract
BACKGROUND Patellar component design in total knee arthroplasty (TKA) can influence patellofemoral kinematics and clinical outcomes. The medialized dome design (MDD) aligns the patella apex more medially, while the anatomic patella design (APD) aims to replicate the native patella's shape and tracking. Although biomechanical studies suggest potential benefits of APD, clinical evidence remains inconclusive. METHODS A systematic review and meta-analysis following PRISMA guidelines was conducted to compare the clinical outcomes of MDD and APD in a modern posterior-stabilized TKA (ATTUNE system). We searched PubMed, Scopus, Embase, and Web of Science on January 10, 2025, without language or date restrictions. Eligible studies included randomized controlled trials (RCTs) and comparative cohort designs evaluating patient-reported outcome measures (PROMs), revisions, complications, range of motion (ROM), and radiologic measures of patellar stability. Risk of bias was assessed using RoB-2 for RCTs and ROBINS-I for cohort studies. Pooled effect sizes were calculated using Hedges's g and random-effects modeling. RESULTS Seven studies, including three RCTs and four cohort studies, with a total of 1,069 patients and 1,113 knees (507 APD vs. 606 MDD), were included. The meta-analysis demonstrated no significant difference in PROMs (Hedges's g = 0.09; 95% CI [-0.04 to 0.22]; P = 0.17) or ROM (Hedges's g = 0.02; 95% CI [-0.21 to 0.26]; P = 0.83) between APD and MDD. While revision rates and complications were higher for APD, the differences were not statistically significant compared to MDD (14 vs 9). Radiographic measures showed inconsistencies and did not definitively favor either design. CONCLUSIONS Current evidence suggests that APD offers no clear clinical advantage over MDD in the ATTUNE posterior-stabilized TKA. Both designs yield broadly comparable PROMs and knee function outcomes. Larger RCTs with extended follow-up are warranted to clarify the safety of APD. LEVEL OF EVIDENCE III.
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Affiliation(s)
- Sina Hajiaghajani
- Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Omid Bahrami
- Student Research Committee, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Maryam Alaei
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Mehrvar
- Clinical Research Development Unit (CRDU), Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Mohammad Poursalehian
- Joint Reconstruction Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Orthopedic Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
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Smith LA, LaCour MT, Dennis DA, Komistek RD. Anatomic vs Dome Patella: Is There a Difference Between Fixed- vs Mobile-Bearing Posterior-Stabilized Total Knee Arthroplasties? J Arthroplasty 2021; 36:3773-3780. [PMID: 34362598 DOI: 10.1016/j.arth.2021.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 07/12/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND It has been hypothesized that the patella, working in conjunction with both medial and lateral femoral condyles, can influence kinematic parameters such as posterior femoral rollback and axial rotation. The objective of this study is to determine the in vivo kinematics of subjects implanted with a fixed-bearing (FB) or mobile-bearing (MB) posterior-stabilized (PS) total knee arthroplasty (TKA), with a specific focus on evaluating the impact that Anatomic and Medialized Dome patellar components have on tibiofemoral kinematic patterns. METHODS Tibiofemoral kinematics were assessed for 40 subjects; 20 with an anatomic patella and 20 with a dome patella. Within these groups, 10 subjects received an FB PS TKA and 10 subjects received an MB PS TKA. All subjects were analyzed using fluoroscopy while performing a deep knee bend activity. Kinematics were collected during specific intervals to determine similarities and differences in regard to patella and bearing type. RESULTS The greatest variation in kinematics was detected between the 2 Anatomic patellar groups. Specifically, the MB-Anatomic subjects experienced greater translation of the lateral condyle, the highest magnitude of axial rotation, and the highest range of motion compared to the FB-Anatomic subjects. Subjects with a Dome Patella displayed much variability among the average kinematics, with all parameters between FB and MB cohorts being similar. CONCLUSION The findings in this study suggest that subjects with an Anatomic patellar component could have more normal kinematic patterns with an MB PS TKA as opposed to an FB PS TKA, while subjects with a Dome patella could achieve similar kinematics regardless of TKA type.
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Affiliation(s)
- Lauren A Smith
- Center for Musculoskeletal Research, University of Tennessee-Knoxville, Knoxville, TN
| | - Michael T LaCour
- Center for Musculoskeletal Research, University of Tennessee-Knoxville, Knoxville, TN
| | | | - Richard D Komistek
- Center for Musculoskeletal Research, University of Tennessee-Knoxville, Knoxville, TN
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Williams HA, Broberg JS, Howard JL, Lanting BA, Teeter MG. Effect of gap balancing and measured resection techniques on implant migration and contact kinematics of a cementless total knee arthroplasty. Knee 2021; 31:86-96. [PMID: 34119998 DOI: 10.1016/j.knee.2021.05.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/05/2021] [Accepted: 05/21/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND The purpose of this study was to compare implant migration and tibiofemoral contact kinematics of a cementless primary total knee arthroplasty (TKA) implanted using either a gap balancing (GB) or measured resection (MR) surgical technique. METHODS Thirty-nine patients underwent TKA via a GB (n = 19) or a MR (n = 20) surgical technique. Patients received an identical fixed-bearing, cruciate-retaining cementless implant. Patients underwent a baseline radiostereometric analysis (RSA) exam at two weeks post-operation, with follow-up visits at six weeks, three months, six months, and one year post-operation. Migration including maximum total point motion (MTPM) of the femoral and tibial components was calculated over time. At the one year visit patients also underwent a kinematic exam via RSA. RESULTS Mean MTPM of the tibial component at one year post-operation was not different (mean difference = 0.09 mm, p = 0.980) between the GB group (0.85 ± 0.37 mm) and the MR group (0.94 ± 0.41 mm). Femoral component MTPM at one year post-operation was also not different (mean difference = 0.27 mm, p = 0.463) between the GB group (0.62 ± 0.34 mm) and the MR group (0.89 ± 0.44 mm). Both groups displayed similar kinematic patterns. CONCLUSIONS There was no difference in implant migration and kinematics of a single-radius, cruciate retaining cementless TKA performed using a GB or MR surgical technique. The magnitude of migration suggests there is low risk of early loosening. The results provide support for using the cementless implant with either a GB or MR technique.
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Affiliation(s)
- Harley A Williams
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Jordan S Broberg
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - James L Howard
- Department of Surgery, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Brent A Lanting
- Department of Surgery, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Matthew G Teeter
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Surgery, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
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Kono K, Tomita T, Yamazaki T, Iwamoto K, Tamaki M, D'Lima DD. Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty. Knee 2021; 30:163-169. [PMID: 33932828 DOI: 10.1016/j.knee.2021.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/22/2021] [Accepted: 04/05/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND While patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism. METHODS We performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion. RESULTS There were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing. CONCLUSION Despite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.
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Affiliation(s)
- Kenichi Kono
- Department of Molecular Medicine Arthritis Research, The Scripps Research Institute, CA, USA; Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tetsuya Tomita
- Department of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takaharu Yamazaki
- Department of Information Systems, Faculty of Engineering, Saitama Institute of Technology, Saitama, Japan
| | - Keiji Iwamoto
- Department of Orthopaedic Surgery, Osaka Medical Center, Osaka, Japan
| | - Masashi Tamaki
- Department of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Darryl D D'Lima
- Department of Molecular Medicine Arthritis Research, The Scripps Research Institute, CA, USA; Shiley Center for Orthopaedic Research and Education at Scripps Clinic, CA, USA.
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Kinematically aligned total knee arthroplasty reproduces native patellofemoral biomechanics during deep knee flexion. Knee Surg Sports Traumatol Arthrosc 2019; 27:1520-1528. [PMID: 30370439 DOI: 10.1007/s00167-018-5270-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/23/2018] [Indexed: 12/17/2022]
Abstract
PURPOSE The implant positioning for kinematically aligned total knee arthroplasty (TKA) differs fundamentally from conventional mechanically aligned TKA. This difference may affect patellofemoral (PF) biomechanics after TKA. This cadaveric study tested the hypothesis that kinematically aligned TKA would restore PF biomechanics to the native condition better than mechanically aligned TKA. METHODS Seven pairs (14 knees) of fresh-frozen cadavers were tested. All specimens were mounted on a customized knee-testing system and digitized using a Microscribe 3DLX instrument (Revware Inc., Raleigh, NC, USA) to measure patellar kinematics in terms of patellar varus/valgus rotation, medial/lateral position, flexion/extension rotation and proximal/distal position at knee flexion angles of 0°, 30°, 60°, 90°, and 120°. The medial and lateral PF joint contact pressure distributions at 120° of knee flexion were measured using a K-scan system (Tekscan Inc., Boston, MA, USA). All patellae remained unresurfaced. For each pair, one knee was randomly assigned to kinematically aligned TKA and the other to mechanically aligned TKA performed using the conventional measured resection technique. During kinematically aligned TKA, the amount of femur and tibia resected was equivalent to implant thickness to maintain the patient-specific joint line. All patellar kinematics were measured and compared between the native condition and after surgery. RESULTS The patellae of mechanically aligned TKA rotated more valgus and was positioned more laterally compared with those of kinematically aligned TKA at knee flexion angles ≥ 90°. Neither the patellar flexion/extension rotation nor the proximal/distal position differed between either prosthetic knee design and the native knee at all flexion angles. The contact pressure distribution between the medial and lateral PF joint after kinematically aligned TKA were similar to those of the native knee, while the lateral PF joint contact pressure after mechanically aligned TKA was higher than that of the native knee (p = 0.038). CONCLUSIONS Kinematically aligned TKA better restores patellar kinematics and PF contact pressure distribution to the native condition than mechanically aligned TKA during deep knee flexion. These findings provide clues to understand why kinematically aligned TKA is associated with less anterior knee pain and better PF functional performance compared to mechanically aligned TKA. Patients undergoing kinematically aligned TKA may experience a more normal feeling during deep knee flexion activities.
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In vivo validation of patellofemoral kinematics during overground gait and stair ascent. Gait Posture 2018; 64:191-197. [PMID: 29929162 PMCID: PMC6084796 DOI: 10.1016/j.gaitpost.2018.06.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 02/02/2023]
Abstract
BACKGROUND The patellofemoral (PF) joint is a common site for non-specific anterior knee pain. The pathophysiology of patellofemoral pain may be related to abnormal motion of the patella relative to the femur, leading to increased stress at the patellofemoral joint. Patellofemoral motion cannot be accurately measured using conventional motion capture. RESEARCH QUESTION The aim of this study was to determine the accuracy of a biplane radiography system for measuring in vivo PF motion during walking and stair ascent. METHODS Four subjects had three 1.0 mm diameter tantalum beads implanted into the patella. Participants performed three trials each of over ground walking and stair ascent while biplane radiographs were collected at 100 Hz. Patella motion was tracked using radiostereophotogrammetric analysis (RSA) as a "gold standard", and compared to a volumetric CT model-based tracking algorithm that matched digitally reconstructed radiographs to the original biplane radiographs. RESULTS The average RMS difference between the RSA and model-based tracking was 0.41 mm and 1.97° when there was no obstruction from the contralateral leg. These differences increased by 34% and 40%, respectively, when the patella was at least partially obstructed by the contralateral leg. The average RMS difference in patellofemoral joint space between tracking methods was 0.9 mm or less. SIGNIFICANCE Previous validations of biplane radiographic systems have estimated tracking accuracy by moving cadaveric knees through simulated motions. These validations were unable to replicate in vivo kinematics, including patella motion due to muscle activation, and failed to assess the imaging and tracking challenges related to contralateral limb obstruction. By replicating the muscle contraction, movement velocity, joint range of motion, and obstruction of the patella by the contralateral limb, the present study provides a realistic estimate of patellofemoral tracking accuracy for future in vivo studies.
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