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Greenberg A, Cohen D, Shahabinezhad A, Barimani B, Wolfstadt J, Backstein D. Good Short-Term Survivorship of Constrained Condylar Revision Knee Implants With Medial Pivot Kinematics: A Level IV Retrospective Study. J Arthroplasty 2024; 39:S275-S279. [PMID: 38395111 DOI: 10.1016/j.arth.2024.02.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/10/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND The need for revision total knee arthroplasty surgery is increasing worldwide, and, in many cases, a constrained implant is required to provide joint stability. The purpose of this study was to examine the early loosening and functional outcome of a novel constrained condylar (CCK) revision total knee system designed to have medial pivot (MP) kinematics. METHODS A retrospective cohort study was performed, collecting clinical data from all patients who underwent revision total knee arthroplasty using a novel MP CCK system with a minimum four-year clinical follow-up. Patient demographics, survivorship, complications, and Forgotten Joint Score were analyzed based upon chart review. RESULTS There were 49 patients available for follow-up, who had a 100% survivorship free of aseptic loosening. All-cause revision survivorship was 92%. There were 4 patients who subsequently underwent rerevision. The causes for rerevision included periprosthetic joint infection in 2 patients, coronal plane instability in one patient, and a traumatic knee dislocation in one patient. There were 45 patients who completed the Forgotten Joint Score, who had an average of 49.8 (± 32.8, range 6.25 to 100). CONCLUSIONS At 4 years, mid-term follow-up, this novel CCK revision total knee system designed to have MP kinematics had good patient-reported outcomes with no revision for aseptic loosening. Future studies should evaluate the mid- and long-term survivorship of this innovative implant.
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Affiliation(s)
- Arieh Greenberg
- Granovsky Gluskin Orthopedic Division, Sinai Health System, University of Toronto, Toronto, ON, Canada
| | - Daniel Cohen
- Granovsky Gluskin Orthopedic Division, Sinai Health System, University of Toronto, Toronto, ON, Canada
| | | | - Bardia Barimani
- Department of Orthopaedics, Arthroscopy & Joint Reconstruction, University of Texas Medical Branch at Galveston, Galveston, Texas
| | - Jesse Wolfstadt
- Granovsky Gluskin Orthopedic Division, Sinai Health System, University of Toronto, Toronto, ON, Canada
| | - David Backstein
- Granovsky Gluskin Orthopedic Division, Sinai Health System, University of Toronto, Toronto, ON, Canada
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Faschingbauer M, Hambrecht J, Schwer J, Martin JR, Reichel H, Seitz A. Tibial insert design significantly alters knee kinematics using a single cruciate-retaining total knee implant. Bone Jt Open 2024; 5:592-600. [PMID: 39019478 PMCID: PMC11254455 DOI: 10.1302/2633-1462.57.bjo-2024-0033.r1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 07/19/2024] Open
Abstract
Aims Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))? Methods Overall, 15 cadaveric knee joints were examined with a CR implant with three different tibial inserts (CR, UC, and MC) using an established knee joint simulator. The effects on coronal alignment, medial and lateral femoral roll back, femorotibial rotation, bony rotations (femur, tibia, and patella), and patellofemoral length ratios were determined. Results No statistically significant differences were found regarding coronal alignment (p = 0.087 to p = 0.832). The medial congruent insert demonstrated restricted femoral roll back (mean medial 37.57 mm; lateral 36.34 mm), while the CR insert demonstrated the greatest roll back (medial 42.21 mm; lateral 37.88 mm; p < 0.001, respectively). Femorotibial rotation was greatest with the CR insert with 2.45° (SD 4.75°), then the UC insert with 1.31° (SD 4.15°; p < 0.001), and lowest with the medial congruent insert with 0.8° (SD 4.24°; p < 0.001). The most pronounced patella shift, but lowest patellar rotation, was noted with the CR insert. Conclusion The MC insert demonstrated the highest level of constraint of these inserts. Femoral roll back, femorotibial rotation, and single bony rotations were lowest with the MC insert. The patella showed less shifting with the MC insert, but there was significantly increased rotation. While the medial congruent insert was found to have highest constraint, it remains uncertain if this implant recreates native knee kinematics or if this will result in improved patient satisfaction.
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Affiliation(s)
| | - Jakob Hambrecht
- Department of Orthopedic Surgery, RKU, University of Ulm, Ulm, Germany
| | - Jonas Schwer
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany
| | - John R. Martin
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Heiko Reichel
- Department of Orthopedic Surgery, RKU, University of Ulm, Ulm, Germany
| | - Andreas Seitz
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany
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Li G, Zhou C, Li S, Yu J, Foster T, Bedair H. Tibiofemoral articulation and axial tibial rotation of the knee after a cruciate retaining total knee arthroplasty. Knee Surg Relat Res 2024; 36:20. [PMID: 38790070 PMCID: PMC11127289 DOI: 10.1186/s43019-024-00224-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
PURPOSE Numerous research has reported that total knee arthroplasty (TKA) cannot reproduce axial tibial rotations of normal knees. The objective of this study was to measure the tibiofemoral articular contact motions and axial tibial rotations of TKA knees to investigate the mechanism causing the knee kinematics change of after TKAs. METHODS Eleven patients with unilateral cruciate retaining (CR) TKA were tested for measurements of knee motion during a weight-bearing flexion from 0° to 105° using an imaging technique. The tibiofemoral contact kinematics were determined using the contact points on medial and lateral surfaces of the tibia and femoral condyles. Axial tibial rotations were calculated using the differences between the medial and lateral articulation distances on the femoral condyles and tibial surfaces at each flexion interval of 15°. RESULTS On femoral condyles, articular contact distances are consistently longer on the medial than on the lateral sides (p < 0.05) up to 60° of flexion, corresponding to internal tibial rotations (e.g., 1.3° ± 1.0° at 15-30° interval). On tibial surfaces, the articular contact point on the medial side moved more posteriorly than on the lateral side at low flexion angles, corresponding to external tibial rotations (e.g., -1.4° ± 1.8° at 15-30° interval); and more anteriorly than on the lateral sides at mid-range flexion, corresponding to internal tibial rotations (e.g., 0.8° ± 1.7° at 45-60° interval). At higher flexion, articular motions on both femoral condyles and tibial surfaces caused minimal changes in tibial rotations. CONCLUSIONS These results indicate that the axial tibial rotations of these TKA knees were mainly attributed to asymmetric articulations on the medial and lateral femoral condyles and tibial surfaces. The data can help understand the mechanisms causing axial tibial rotations of TKA knees and help improve implant designs for restoration of normal knee kinematics.
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Affiliation(s)
- Guoan Li
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA.
| | - Chaochao Zhou
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA
| | - Sophia Li
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA
| | - Jia Yu
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA
| | - Timothy Foster
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA
| | - Hany Bedair
- Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital/Massachusetts General Brigham, 159 Wells Avenue, Newton, MA, 02459, USA
- Department of Orthopaedics, Massachusetts General Hospital, Boston, MA, USA
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Rossi SMP, Sangaletti R, Jannelli E, Bova D, Montagna A, Benazzo F. PCL preservation or sacrifice does not influence clinical outcomes and survivorship at mid-term follow-up of a J-curve CR total knee replacement with a medial congruent liner and a functional coronal alignment. Arch Orthop Trauma Surg 2024; 144:307-313. [PMID: 37612567 DOI: 10.1007/s00402-023-05033-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/09/2023] [Indexed: 08/25/2023]
Abstract
BACKGROUND In recent years, increasing interest has arisen for medial pivoting TKA implants, designed to mimic the physiological knee kinematics, maximizing the contact area on the medial compartment of the knee, increasing anterior-posterior stability, and contributing to a ball-in-socket effect that allows the posterior cruciate sacrifice without a post-CAM mechanism. The medial congruent liner works with a J-curve cruciate-retaining (CR) femur without a real ball-in-socket design. The aim of this study was to evaluate the clinical outcomes and survival of these implants, with or without PCL sparing, at a medium follow-up. METHODS Between October 2016 and October 2018, 165 TKRs were performed in 161 patients (69.2% females and 30.8% males) and prospectively followed. Mean follow-up was 72 ± 12 months. All surgeries were performed using an extramedullary device and the same prosthetic implant. Patients were matched in two groups: in 80 patients, the PCL was preserved; in 85 patients, the PCL was sacrificed with a reduction of the tibial slope. RESULTS The OKS and KSS improved in both groups. The difference between the two groups at the final follow-up was not statistically significant. Good-to-excellent clinical results according to the KSS were achieved in 93% of the knees in the PCP group and in 95% in the PCS group. At final follow-up, the Forgotten Joint Score (FJS) was 73.6 in the PCP group and 74.1 in the PCS group with no statistical difference between the two groups (P > 0.05). CONCLUSIONS TKA with a medially congruent insert, showed promising results at mid-term follow-up, PCL preservation or sacrifice did not affect the clinical outcomes and survival. Further follow-up will be needed to evaluate these results at long term.
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Affiliation(s)
- Stefano Marco Paolo Rossi
- Sezione di Chirurgia Protesica ad Indirizzo Robotico, Unità di Traumatologia dello Sport, UOC Ortopedia e Traumatologia, Fondazione Poliambulanza, Via Bissolati, 57, 25124, Brescia, Italy.
| | - Rudy Sangaletti
- Sezione di Chirurgia Protesica ad Indirizzo Robotico, Unità di Traumatologia dello Sport, UOC Ortopedia e Traumatologia, Fondazione Poliambulanza, Via Bissolati, 57, 25124, Brescia, Italy
| | - Eugenio Jannelli
- Clinica Ortopedica e Traumatologica, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Davide Bova
- U.O. Ortopedia e Traumatologia, Humanitas Mater Domini, Castellanza, Italy
| | - Alice Montagna
- Sezione di Chirurgia Protesica ad Indirizzo Robotico, Unità di Traumatologia dello Sport, UOC Ortopedia e Traumatologia, Fondazione Poliambulanza, Via Bissolati, 57, 25124, Brescia, Italy
- Clinica Ortopedica e Traumatologica, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Francesco Benazzo
- Sezione di Chirurgia Protesica ad Indirizzo Robotico, Unità di Traumatologia dello Sport, UOC Ortopedia e Traumatologia, Fondazione Poliambulanza, Via Bissolati, 57, 25124, Brescia, Italy
- IUSS, Istituto Universitario di Studi Superiori, Pavia, Italy
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Jones BK, Carlson BJ, Scott DF. Better flexion and early recovery with medial-stabilized vs single-radius total knee arthroplasty with kinematic alignment: Two-year clinical results. Knee 2023; 43:217-223. [PMID: 37467702 DOI: 10.1016/j.knee.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/27/2023] [Accepted: 06/30/2023] [Indexed: 07/21/2023]
Abstract
BACKGROUND There are few studies comparing outcomes in patients with posterior cruciate ligament-sacrificing single-radius (SR) versus medial-stabilized (MS) knee devices. Both types of implants are designed to maximize deep-flexion and to maintain stability throughout the knee flexion arc. The aim of this study was to determine whether two-year outcomes differ between these two implant groups. METHODS Two-hundred and ten patients took part in this retrospective cohort single center study. The SR patients (n = 109) were enrolled in one randomized trial, and the MS knees (n = 101) in another. Patient consent and Investigative Review Board approval was obtained. Radiographs and clinical outcomes were gathered preoperatively and at six weeks, six months, one year and two years. RESULTS There were no statistically significant differences between treatment groups in terms of preoperative demographic characteristics. The MS group had significantly better knee flexion starting at six months postoperative through two years postoperatively (p < 0.05 - p< 0.001). The Knee Society Pain/Motion score was better in the MS group at one year (95.41 vs 90.86, p < 0.002). The Knee Society Pain score was also better in the MS group starting at six weeks through one year (six weeks: 35.3 vs 30, p = 0.007; one year: 46.4 vs 42.4, p = 0.005, respectively). CONCLUSION The MS group had better clinical outcomes than the SR group, with significantly greater knee flexion from six months through two years, better Knee Society Pain scores at six weeks through one year, and higher Knee Society Pain/Motion scores at six weeks and one year postoperatively. LEVEL OF EVIDENCE I.
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Affiliation(s)
- Brett K Jones
- Elson S. Floyd College of Medicine Washington State University, 412 E Spokane Falls Blvd, Spokane, WA 99202, USA.
| | - Brian J Carlson
- Elson S. Floyd College of Medicine Washington State University, 412 E Spokane Falls Blvd, Spokane, WA 99202, USA.
| | - David F Scott
- Elson S. Floyd College of Medicine Washington State University, 412 E Spokane Falls Blvd, Spokane, WA 99202, USA; Spokane Joint Replacement Center, Inc., Spokane, WA, USA.
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Scott DF, Hellie AA. Mid-Flexion, Anteroposterior Stability of Total Knee Replacement Implanted with Kinematic Alignment: A Randomized, Quantitative Radiographic Laxity Study with Posterior-Stabilized and Medial-Stabilized Implants. J Bone Joint Surg Am 2023; 105:9-19. [PMID: 36574642 DOI: 10.2106/jbjs.22.00549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
UPDATE This article was updated on January 4, 2023, because of a previous error, which was discovered after the preliminary version of the article was posted online. On page 16, in Figure 5, the x-axis that had read "P<0.0086" now reads "KSS Pain (p=0.02)," and the value for the MS group that had read "48.9" now reads "48.8."This article was updated on January 6, 2022, because of a previous error. On page 13, in the section entitled "Results," the sentence that had read "However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the MS group (2.3 versus 5.4 mm; p = 0.008)." now reads "However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008)." BACKGROUND Stability in mid-flexion is important for satisfactory clinical outcomes following total knee arthroplasty (TKA). The purpose of the present study was to compare the anteroposterior stability of knees that had been treated with a posterior-stabilized (PS) device or a medial-stabilized (MS) device. We hypothesized that mid-flexion laxity would be greater in the PS group and that clinical outcome scores would be better for the group with lower laxity. METHODS Sixty-three patients who had been randomly selected from a larger randomized, prospective, blinded clinical trial underwent primary TKA with either a PS implant (n = 30) or an MS implant (n = 33). Range of motion, the Knee Society Score (KSS), and the Forgotten Joint Score (FJS) were collected, and anteroposterior laxity with the knee in 45° and 90° of flexion was evaluated with stress radiographs. RESULTS In 45° of flexion, the MS group demonstrated significantly less total anteroposterior displacement than the PS group (mean, 3.6 versus 16.5 mm; p ≤ 0.0001). In 90° of flexion, the total anteroposterior displacement was not significantly different for the 2 groups when both male and female patients were included (mean, 3.9 versus 5.9; p = 0.07). However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008). The groups did not differ significantly in terms of preoperative age, body mass index, sex distribution, FJS, KSS, or range of motion, and they also did not differ in terms of postoperative FJS or range of motion. However, all 33 patients in the MS group returned to sports as indicated in question 12 of the FJS, compared with 19 subjects in the PS group (p = 0.0001). The postoperative KSS Pain, Pain/Motion, and Function scores were all significantly higher in the MS group than the PS; specifically, the mean KSS Pain score was 48.8 in the MS group, compared with 44.8 in the PS group (p = 0.02); the mean KSS Pain/Motion score was 98.4 in the MS group, compared with 89.5 in the PS group (p < 0.0001); and the mean KSS Function score was 95.5 in the MS group, compared with 85.7 in the PS group (p = 0.003). CONCLUSIONS Mid-flexion laxity was greater in patients with PS implants than in those with MS implants, and laxity in 90° was greater in the subset of female patients in the PS group. The decreased laxity observed in the MS group correlated with higher KSS Pain, Pain/Motion, and Function scores as well as with a higher rate of return to sports activities. LEVEL OF EVIDENCE Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.
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Affiliation(s)
- David F Scott
- Spokane Joint Replacement Center, Inc., Spokane, Washington.,Elson S. Floyd College of Medicine, Washington State University, Spokane, Washington
| | - Amy A Hellie
- Spokane Joint Replacement Center, Inc., Spokane, Washington
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Wittig U, Moshammer M, Vielgut I, Hauer G, Reinbacher P, Leithner A, Sadoghi P. Higher use of fixed-bearing over mobile-bearing and posterior-stabilized over medial pivot designs in total knee arthroplasty (TKA): a systematic comparative analysis using worldwide arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland. Arch Orthop Trauma Surg 2023; 143:1021-1029. [PMID: 35303145 PMCID: PMC9925559 DOI: 10.1007/s00402-022-04410-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 02/27/2022] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The aim of this study was to compare the use of mobile-bearing, fixed-bearing, posterior-stabilized (PS) and medial pivot design to describe epidemiological differences and subsequent outcomes. MATERIALS AND METHODS A systematic literature search was performed using the NORE website to identify the relevant arthroplasty registers. Inclusion criteria were the following: (1) reports had to be publicly available, (2) reports had to be written in German or English language, (3) differentiation between mobile- and fixed-bearing, posterior-stabilized, and if possible, medial pivot designs had to be possible from the present reports, and (4) data had to be reported for at least three consecutive years and the latest report had to be from the year 2020 to retrieve recent data. RESULTS Six registries (England and Wales, Australia, Norway, New Zealand, Germany, Switzerland) offered sufficient data according to the inclusion criteria. In all countries, the dominant type of bearing used for total knee arthroplasty (TKA) was fixed-bearing, with percentages ranging from 60.8% to 84.1% in 2018, 63.6% to 85.7% in 2019 and 66.2% to 87.4% in 2020. A large variation was observed concerning mobile-bearing design, which showed a range from 2.8% to 39.2% in 2018, 2.6% to 36.4% in 2019 and 2.9% to 33.8% in 2020. Some variation was found regarding the use of PS TKA, as its percentage frequency ranged from 9.7% to 29.2% in 2018, 9.8% to 29.4% in 2019 and 10.1% to 28.5% in 2020. Medial pivot design had a share of 9.1% in 2018, 8.6% in 2019 and 8.4% in 2020 in Australia, while it only accounted for 1.4% in 2018, 2.1% in 2019 and 2.5% in 2020 in Germany. CONCLUSION The comparison of arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland revealed large differences regarding the application of posterior-stabilized designs, but also common ground considering the overwhelming use of fixed-bearing inserts, which, when inserted correctly, eradicate the potential complication of bearing dislocation. Arthroplasty registers offer a real-world clinical perspective with the aim to improve quality and patient safety.
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Affiliation(s)
- Ulrike Wittig
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
| | - Maximilian Moshammer
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
| | - Ines Vielgut
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
| | - Georg Hauer
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria.
| | - Patrick Reinbacher
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
| | - Andreas Leithner
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
| | - Patrick Sadoghi
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5a, Graz, Austria
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Scott DF, Gray CG. Outcomes are Better With a Medial-Stabilized vs a Posterior-Stabilized Total Knee Implanted With Kinematic Alignment. J Arthroplasty 2022; 37:S852-S858. [PMID: 35189286 DOI: 10.1016/j.arth.2022.02.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/04/2022] [Accepted: 02/14/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND There is no consensus whether a posterior-stabilized (PS) total knee device is superior to a more congruent, cruciate-substituting, medial-stabilized device (MS). This study compared the clinical outcomes of these devices. The primary hypothesis was that the clinical outcomes would be better in the MS group implanted with kinematic alignment. METHODS This prospective, randomized, single-center Level 1 study compared the outcomes of 99 patients who received a PS device and 101 patients who received an MS device implanted with kinematic alignment. Institutional Review Board approval and informed consent were obtained. Clinical and radiographic assessments were performed preoperatively, 6 weeks, 6 months, and annually. RESULTS All subjects reached the minimum follow-up of 2 years. There were no statistically significant differences in demographic characteristics, preoperative scores, or alignment (preoperative or postoperative). Tourniquet time was 7.24% longer for the PS group (40.28 min vs 37.56 min, P < .0086). There were significant differences between groups for the 1-year and 2-year Knee Society scores, Forgotten Joint Score, and ROM; in every case favoring the MS group. The FJS was 68.3 in the MS group at 2 years and 58.3 in the PS group (P = .02). The maximum flexion at 2 years was 132° in the MS group and 124° in the PS group (P < .0001). CONCLUSION The clinical outcomes of the MS group at 1 and 2 years were better. At the minimum 2-year follow-up, the results demonstrate the superiority of the medial-stabilized device in terms of multiple clinical outcomes. LEVEL OF EVIDENCE I.
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Affiliation(s)
- David F Scott
- Spokane Joint Replacement Center Inc., Spokane, Washington; Washington State University, Elson S. Floyd College of Medicine, Spokane, Washington
| | - Celeste G Gray
- Spokane Joint Replacement Center Inc., Spokane, Washington
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