Total Knee Arthroplasty Using a Posterior Cruciate Ligament Sacrificing Medial Pivot Knee: Minimum 5-year Follow-up Results

Posterior Cruciate Ligament Preservation versus Posterior Cruciate Ligament Sacrifice: Comparing Patient Outcomes in Medial Congruent Total Knee Arthroplasty

This study aimed to compare outcomes and complication rates between posterior cruciate ligament (PCL) retention and excision utilizing a medial congruent (MC) polyethylene insert in total knee arthroplasty (TKA) in a specialized ambulatory surgery center (ASC) dedicated to hip and knee arthroplasty. A retrospective review was performed between May 2023 and October 2023 analyzing 398 patients who underwent primary MC TKA by high-volume joint arthroplasty surgeons (n = 9) with either PCL preservation (n = 264) or sacrifice (n = 134) in a single free-standing ASC. Patients were matched chronologically on a 2:1 basis. Demographics, baseline function, 90-day complications, and patient-reported outcomes were recorded for each patient. There were no differences in preoperative baseline function or patient-reported outcome measures, Charlson Comorbidity Index, or American Society of Anesthesiologists class among patient groups. The PCL-preserve and PCL-sacrifice cohorts showed significant variation in 12-week postoperative Knee Injury and Osteoarthritis Outcome, Junior (KOOS, JR.) scores. Specifically, the number of patients who achieved the minimal clinically important difference (MCID) in KOOS, JR. scores was higher in the PCL-sacrifice group (p < 0.05). Yet, no complications within the 90-day period were associated with PCL status and other patient-reported outcomes. This study comparing outcomes between MC TKAs with PCL retention and sacrifice suggests that both techniques are viable options with similar functional outcomes, pain scores, and complication rates, which may have benefits in an ASC setting. The PCL-sacrifice group exhibited a statistically significant increase in patients who achieved the MCID in KOOS, JR. score compared with the PCL-preserving at early follow-up. Future research should employ prospective, randomized designs to further validate these findings and explore long-term implications.

Sitting Sideways Causes Different Femoral-Tibial Rotations in Each Knee

Purpose According to a previous study, asymmetrical kneeling, such as sitting sideways, does not exhibit asymmetrical movements. Rotational analyses of each femur and tibia help explain why rotational knee kinematics while sitting sideways do not exhibit asymmetrical movement. We aimed to assess the rotation of the femur and tibia in normal knees while sitting sideways. Methods Each volunteer sat sideways under fluoroscopy. Two-dimensional and three-dimensional registration techniques were used. After evaluating the femoral rotation angle relative to the tibia at each flexion angle, the femoral and tibial sole rotation angles at each flexion angle were compared between the ipsilateral and contralateral knees. Results While sitting sideways, both knees showed femoral external rotation relative to the tibia with flexion. In the ipsilateral knees, the femurs exhibited an external rotation of 26.3 ± 8.0°, from 110° to 150° of flexion. Conversely, the tibia exhibited an external rotation of 12.2 ± 7.8°, from 110° to 150° of flexion. From 110° to 150° of flexion, femoral external rotation was significantly larger than tibial external rotation. In the contralateral knees, the femurs exhibited an internal rotation of 23.8 ± 6.3°, from 110° to 150° of flexion (110°, p < 0.001; 120°, p < 0.001; 130°, p < 0.001; 140°, p < 0.001; and 150°, p < 0.001). Contrastingly, the tibia exhibited an internal rotation of 30.4 ± 8.8°, from 110° to 150° of flexion, which was significantly larger than femoral internal rotation (110°, p = 0.002; 120°, p < 0.001; 130°, p < 0.001; 140°, p < 0.001; and 150°, p < 0.001). Conclusions Although bilateral knees exhibited femoral external rotation relative to the tibia while sitting sideways, the ipsilateral and contralateral knees showed femoral and tibial sole rotations in opposite directions. In particular, the contralateral knees might show a strained movement because both femurs and tibias exhibited internal rotation with flexion. Patients who have undergone guided-motion total knee arthroplasty (TKA) or medial-pivot TKAs might be advised to avoid sitting sideways.

PCL retained is safe in medial pivot TKA-a prospective randomized trial

PURPOSE

Medial pivot (MP) designs resemble native knee kinematics and restore the "natural" kinematics of a knee after total knee arthroplasty (TKA). However, whether to preserve or resect the posterior cruciate ligament (PCL) is still under debate. We inquired whether sacrificing the PCL would improve range of motion, functional outcomes, and limb alignment compared to preserving the PCL in TKA using medial pivot implants (MP-TKA).

METHODS

This prospective, double-blinded, randomized controlled trial consisted of 33 patients (66 knees) undergoing bilateral simultaneous MP-TKA. In one knee, a PCL preservation technique was performed, and in the contralateral knee, the PCL was resected. The primary outcome was postoperative range of motion (ROM). The secondary outcomes were visual analogue scale (VAS) score for knee pain at walking, Knee Injury and Osteoarthritis Outcome Score for symptoms (KOOS-S) and quality of life (KOOS-QoL), Oxford knee score (OKS), and Forgotten Joint Score (FJS), and measurement of the mechanical femoral-tibial axis (mFTA) on X-ray images. All patients were followed up for a minimum of 2 years after surgery.

RESULTS

Patients who underwent MP-TKA with PCL preservation had a similar ROM at 2 years (125.45 ± 7.00 vs. 126.21 ± 6.73, p = 0.65) as those who underwent MP-TKAs with PCL resection. There was also no difference in VAS score (1.94 ± 0.79 vs. 2.00 ± 0.71, respectively, p = 0.51), OKS (39.97 ± 2.01 vs. 39.67 ± 2.03, respectively, p = 0.52), KOOS-S (84.41 ± 3.77 vs. 84.19 ± 3.57, respectively, p = 0.92), KOOS-QoL (82.94 ± 4.76 vs. 82.75 ± 4.70, respectively, p = 0.84), or FJS (72.66 ± 8.99 vs. 72.35 ± 8.64, respectively, p = 0.76) at the 2-year follow-up. No difference in the measurement of the mFTA was found between the two groups (180.27 ± 2.25 vs. 181.30 ± 2.13, respectively, p = 0.59).

CONCLUSION

This study demonstrated that both medial pivot TKA with PCL preservation and PCL resection achieved excellent results. There was no difference at the 2-year follow-up in terms of postoperative ROM, patient-reported outcomes, or radiographic evaluation.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

PCL retention demonstrates better functional scores and gait patterns in total knee arthroplasty using a medial congruent insert-a prospective study

PURPOSE

Despite Total Knee Arthroplasty (TKA) being one of the most successful procedures for end stage arthritis, nearly 20% of patients undergoing this procedure remain dissatisfied. Various design options have been introduced to reduce this cohort of patients. One such option has been the introduction of the medial congruent (MC) polyethylene design. This study was undertaken to evaluate outcome measures and gait analysis in patients undergoing bilateral single stage TKA where the posterior cruciate ligament (PCL) was retained or excised in contralateral knees.

METHODS

60 bilateral TKA's were performed by a single surgeon using a MC design option from July to Sep 2021. The study lots included patients between the ages of 55 and 70 years with fixed varus deformity of degenerative aetiology, and Kellgren Lawrence Grade 3 and 4 radiological changes. Exclusion criteria were previous surgery to the lower extremities, sero positive arthropathies, post traumatic arthritis, valgus deformity, flexion contractures > 20°, and any pre-existing pathology impacting gait, e.g., poliomyelitis, or neuromuscular disorders. The PCL was retained or sacrificed on contralateral sides for the purpose of this study. Functional scores, outcomes and gait analysis on level and gradient walking were evaluated at a follow-up of 18 months.

RESULTS

At 18, months the Range of Motion (ROM) improved from a preoperative value of 97.3 ± 11.5 to 110.3 ± 6.1 on the PCL retained side (MC-PCL) and from 96.5 ± 10.8 to 113 ± 5.8 on the PCL excised side (MC-PCLX). Knee Society Score (KSS-2011) improved from a preoperative value of 21.2 ± 4.5 to 89.8 ± 3.4 at 18 months postoperatively on the MC-PCL side and from 21.5 ± 4 to 88.2 ± 3.7 on the MC-PCLX side. Forgotten Joint Score (FJS-12) was 8.8 ± 0.7 on the MC-PCL side and 8.1 ± 0.9 on the MC-PCLX side 18 months after surgery. Our gait analysis evaluation demonstrated a lower forefoot pressure in the MC-PCL group in comparison to the MC-PCLX group when subjects were made to walk on a 30° upward incline. This difference was found to be statistically significant.

CONCLUSION

In this study, while ROM was greater in the MC-PCLX study lot, patient satisfaction was higher in the MC-PCL study lot. Gait assessment demonstrated lower forefoot pressure while ascending an incline of 30° in the MC-PCL study lot as compared to the MC-PCLX study lot approximating normal gait patterns.

LEVEL OF EVIDENCE

II.

Modern Total Knee Arthroplasty Bearing Designs and the Role of the Posterior Cruciate Ligament

The role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) surgery continues to be a source of debate among the adult reconstruction community. In native knee flexion, the PCL is comprised of an anterolateral and posteromedial bundle that work together to limit posterior tibial translation and allow adequate femoral rollback for deep flexion. In the arthritic knee, the PCL can often become dysfunctional and attenuated, which led to the development of posterior stabilized (PS) TKA bearing options. PS TKAs implement a cam-post construct to functionally replace a resected PCL. While PS designs may facilitate balancing knees with significant deformity, they are associated with complications such as postfracture, increased wear, and patellar clunk/crepitus. In recent years, newer designs have been popularized with greater degrees of congruency and incorporation of medial and lateral pivoting to better recreate native knee kinematics. The American Joint Registry has confirmed the recent predilection for ultra-congruent and cruciate-retaining TKA inserts over PS TKAs during the last decade. Studies have failed to identify an overall clinical superiority between the cruciate substituting and sacrificing designs. The literature has also failed to identify clinical consequences from PCL resection with modern, more conforming TKA designs. In this article, we review modern PCL sacrificing designs and discuss the impact of each on the kinematics after TKA. We also will delineate the role of the PCL in modern TKA in the hopes to better understand the recent surge in sacrificing but not substituting knee implants.

Medial pivot total knee arthroplasty: Mid-term results

This study aims to evaluate the mid-term results of patients who underwent medial pivot total knee arthroplasty at a single center. A total of 304 knees of 236 patients (40 males, 196 females; mean operation age and standard deviation : 66,64 ±7,09 years; range, 45 to 82 years) treated with medial pivot total knee prosthesis in our center between January 2010 and December 2014 were retrospectively analyzed. The American Knee Society Score, Oxford Knee Score, and especially flexion angles were recorded during pre- and postoperative follow-up. Of the operated knees, 71.2% were unilateral and 28.8% were bilateral. The mean follow-up was 79.30±14.76 months. The postoperative results with the Functional Score, Knee Score, Oxford Score, Total Knee Society Score, and flexion angles were significantly higher compared to baseline (p<0.01). All postoperative scores were significantly lower inpatients aged ≥65years, compared to those aged <65 years (p<0.01). In patients who underwent resection of anterior and posterior the cruciate ligaments, only the mean flexion angles were found to increase (p<0.01). Our study results suggest that medial pivot knee prostheses are reliable in the mid-term and provide favorable results in terms of function and patient satisfaction. Level of Evidence: Level IV retrospective study.

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

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.

Medial Ball and Socket Total Knee Arthroplasty in Indian Population: 5-Year Clinical Results

Background

Medial pivot total knee arthroplasty aims to restore native knee kinematics through highly conforming medial tibiofemoral articulation with survival comparable to contemporary knee designs. The aim of this study was to report preliminary clinical results of medial pivot total knee arthroplasty in an Indian population.

Methods

A retrospective analysis of 45 patients (average age, 62 years; 40 women and 5 men) with end-stage arthritis (Kellgren-Lawrence grade 4) operated with a medial pivot prosthesis was done. All patients were assessed using Knee Society Score (satisfaction, expectation, and functional scores) and Oxford Knee Score, and range of motion was recorded at the end of 5-year postoperative follow-up. In addition, all patients underwent standardized radiological assessment.

Results

At the final follow-up, patients reported significant improvement in mean Knee Society Score (satisfaction, expectation, and functional scores) and Oxford Knee Score (p < 0.05). The mean range of motion achieved at the end of 5 years ranged from 0° (extension) to 118.4° (further flexion). There was no evidence of loosening or osteolysis at a minimum follow-up of 5 years.

Conclusions

These results demonstrated satisfactory clinical and radiological outcomes at 5 years after total knee arthroplasty with a medial pivot design, which may be related to better replication of natural knee kinematics with the medial pivot knee and inherent advantages of this design.

Clinical radiographic outcomes and survivorship of medial pivot design total knee arthroplasty: a systematic review of the literature

BACKGROUND

Total knee arthroplasty is a reliable procedure able to reduce pain and disability in patients suffering from osteoarthritis. However, a considerable percentage of patients still experiences unsatisfactory results. Medial pivot total knee arthroplasty has been introduced in the clinical practice to overcome problems related with classic design implants and better mimic native knee kinematics. The aim of this study was to analyze survivorship and clinical and radiographic outcomes of medial pivot implants.

METHODS

A systematic research was conducted in eight different databases. Thirty-four studies met the inclusion criteria and were included in the analysis. Data on objective and patients-reported outcomes, radiographic alignment, and survivorship were collected and analyzed. Revision rate was expressed as revision per 100 components years.

RESULT

A total of 3377 procedures were included. Mean follow-up was 85.7 months (range, 12-182). The revision per 100 components years was 0.19, which corresponds to a revision rate of 1.9% after 10 years. Mean post-operative range of motion was 117.3 ± 0.4°. Mean clinical and functional Knee Society Score were, respectively, 85.9 ± 1.1 and 84.7 ± 3.5 at final follow-up. Post-operative femorotibial alignment was 177.1 ± 0.5°. Alfa and beta angles were 95.7 ± 0.1° and 89.2 ± 0.1°, respectively. Gamma and delta angles were 2.3 ± 0.6° and 86.7 ± 0.4°.

CONCLUSION

Medial pivoting implants provided excellent survivorship and low revision rate, as well as good-to-excellent results in term of objective and patient-reported clinical outcomes, and reliable correction of radiographic parameters. More high-quality studies with long-term follow-up are needed to clarify the role of medial pivoting implants.

Total Knee Arthroplasty in Rheumatoid Arthritis patients with a medial stabilized prosthesis - A retrospective analysis

BACKGROUND

Total Knee Arthroplasty (TKA) has been described as an effective and successful mode of treatment in alleviation of pain and restoration of function in patients with Rheumatoid Arthritis (RA). The array of bone and soft tissue deformities in RA patients can impact initial success and long term durability of TKA. Medial Pivot (MP) prosthesis is fixed bearing asymmetric pivoting design that provides anterior-posterior stability without any post and conserves bone on the femoral side. There are few reports of suitability of experience with MP in RA.

METHODS

Twenty six patients (average age 55 years) with end stage arthritis secondary to RA operated with MP prosthesis were retrospectively followed up. At a minimum follow up of three years, all patients were assessed using Knee Society Score (KSS), Oxford Knee Score (OKS), Pain Catastrophising Scale (PCS) and radiological outcomes.

RESULTS

At final follow-up, patients reported significant improvement in mean KSS-Objective and Functional scores, Oxford Knee Score and Pain Catastrophising Scale (p < 0.05). The mean range of motion achieved at the end of two years ranged from 0 ͦ (extension) to 109.4 ͦ (full flexion). There was no evidence of loosening or osteolysis at minimum follow up of three years.

CONCLUSION

These results endorse satisfactory clinical and radiological outcomes at minimum follow up of three years following Medial Pivot Prosthetic Knee design in RA patients. Further long term follow up is needed to determine the survival analysis of MP design in these patients.

Loss of Knee Flexion and Femoral Rollback of the Medial-Pivot and Posterior-Stabilized Total Knee Arthroplasty During Early-Stance of Walking in Chinese Patients

Background The medial-pivot (MP) prosthesis was developed to produce more physiological postoperative knee kinematics and better patient satisfaction than traditional prostheses, but outcomes are inconsistent in different studies of Caucasian patients. This study aimed to investigate the postoperative patient satisfaction and in vivo knee kinematics of the MP and posterior-stabilized (PS) prosthesis during gait activity in Chinese patients.

Methods A retrospective analysis of 12 patients was received for this study in each MP group and PS group. Patient-reported satisfaction level and Forgotten Joint Score (FJS) were evaluated with questionnaires. A dual fluoroscopic imaging system was used to investigate in vivo knee kinematics of MP and PS total knee arthroplasty (TKA) during treadmill walking at a speed of 0.4 m/s.

Results Comparable promising patient satisfaction and overall FJS (MP 60.7 ± 15.35 vs. PS 51.3 ± 17.62, p = 0.174) were found between the MP and PS groups. Peak flexion appeared at around 70% of gait cycle with values of 52.4 ± 7.4° for MP and 50.1 ± 3.6° for PS groups (no difference). Both groups maintained a stable position at the stance phase and began to translated anteriorly at toe-off with an amount of 4.5 ± 2.3 mm in the MP and 6.6 ± 2.7 mm in the PS (p = 0.08) group until late swing. The range of this external rotation motion was 5.9 ± 4.8 and 6.2 ± 4.1° (p = 0.79) for the MP and PS, respectively.

Conclusion A similar knee kinematics pattern characterized by a loss of early-stance knee flexion and femoral rollback during walking was observed in the MP and PS TKAs. Our study confirmed similar effectiveness of MP TKA compared to PS TKA in Chinese patients, while the change of knee kinematics of both implants during slow walking should be noted.

Mid-term clinical outcomes and survivorship of medial-pivot total knee arthroplasty-a mean five year follow-up based on one thousand, one hundred and twenty eight cases

PURPOSE

The unique medial-pivot (MP) design of ADVANCE® system largely simulates the movement of a normal knee joint and a high mid- and long-term success rate has been reported in limited populations. The aims of this study are to investigate the mid-term clinical outcomes and survivorship based on a large cohort with 1128 cases.

METHODS

One thousand seven patients received 1276 ADVANCE® MP TKAs from January 2011 to April 2016 in our institution were retrospectively investigated. The range of motion (ROM), the Knee Society Score (KSS), the Knee Society Function Score (KSFS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and the Forgotten Joint Score (FJS) were used to evaluate clinical outcomes and Kaplan-Meier survival curve was used to calculate the survivorship.

RESULTS

In an averaged five year follow-up, the results of 879 patients (1128 knees) were successfully obtained and the clinical outcomes of 1107 knees were recorded. One hundred forty-eight knees (11.6%) were lost to follow-up. Excellent mid-term ROM, KSS, KSFS, and WOMAC score were recorded. A total of 53 complications were identified and most complications were related to the discordance of femoropatellar joint. Taking revision for any reason as end point, the overall survivorship was 99.2% at seven years. When taking all cases lost to follow-up as failures, the survivorship was 83.8% at five years and 50.6% at seven years.

CONCLUSION

For MP designs, the intermediate clinical outcomes are good to excellent and the mid-term survivorship related to reasons other than infection is also satisfactory.

Mid-term survivorship and clinical outcomes of the medial stabilized systems in primary total knee arthroplasty: A systematic review

Introduction

Medial Pivot Total Knee Arthroplasty was introduced in clinical practice in 1990s to reproduce the in vivo-natural knee kinematics. This design is characterized by an asymmetric constraint profile, with aa highly congruent medial compartment, and a less congruent lateral compartment. Short-term outcomes of the medial pivot systems in primary knee arthroplasty have been widely reported in the current literature, however, only few studies have described results beyond 5-year follow-up.

Objectives

The primary objectives of this systematic review of the literature is to analyze the mid-term studies on medial pivot total knee arthroplasty focusing on the reoperation rate, survivorship and clinical outcome scores.

Methods

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried for publications from January 1980 to December 2019 utilizing the following keywords: "medial pivot", "medial stabilized", "medial rotating", "medial congruent", medial ball and socket", "arthroplasty", "TKA", "TKR", and "knee surgery".

Results

18 articles met the inclusion criteria for the present study. The average quality was 11.4 for non-comparative studies and 21.7 for comparative studies based on MINORS criteria. A total 2832 knee arthroplasties were included for the final analysis with an average age of 69 years, and an average follow-up of 8.1 years (minimum 5 years). The overall reoperation rate was 2.4%, with periprosthetic joint infection as the leading cause of revision in 0.9% of cases, followed by aseptic loosening in 0.4% of cases. The average Knee Society Score improved to a mean preoperative score of 40.1 to a mean postoperative score of 89.2. The functional knee society score improved from a mean preoperative score of 44.8 to an average postoperative score of 82.9. The global range of motion improved from 104.8° preoperatively to 115.6° postoperatively.

Conclusion

We found that medial pivot system in primary total knee arthroplasty provide overall mid-term survivorship comparable to other standard implasnts. In addition, medial pivot system is associated with better high-end function compared to standard implants.

Evaluation of the Medial Stabilized Knee Design Using Data From National Joint Registries and Current Literature

BACKGROUND

Various designs of total knee arthroplasty (TKA) have provided satisfactory outcomes for the treatment of knee osteoarthritis for many years. The aim of the study is to evaluate the success and failure rate of the medial stabilized (MS) TKA design through national joint registries and the current literature.

MATERIALS AND METHODS

A comprehensive literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses was carried out through PubMed and MEDLINE database. The international registries analyzed included the National Joint Registry, the Australian Orthopedic Association National Joint Replacement Registry, the Dutch Arthroplasty Register, the New Zealand Orthopedic Association Joint Registry, and the Michigan Arthroplasty Registry Collaborative Quality Initiative. We are reporting descriptive data which include means and percentages of survival rates and revision rates and number of years after the primary procedure. The revision rates and the cumulative revision rates are reported separately for each MS implant.

RESULTS

Our detailed review identified 5 of 12 registries and 25 of 550 studies reporting on the survivorship of an MS TKA design. There were a total of 3684 procedures between the 25 studies, with an average survivorship free of aseptic loosening of 99% at 6.9 years. There are 26,693 (2.5%) MS TKAs in the current National Joint Registry with a mean cumulative revision rate of 2.63% at 5 years, 3.35% at 10 years, and 4.6% at 15 years. The Australian Orthopedic Association National Joint Replacement Registry provides survivorship data on 19,249 (2.9%) MS TKAs, with a mean cumulative revision rate of 3.34% at 5 years, 7.4% at 10 years, and 8.1% at 15 years. The Dutch Arthroplasty Register contains survivorship data on 1490 MS designs and a mean revision rate of these implants is 0.8% at 1 year, 5.95% at 5 years, and 9.8% at 10 years. The Evolution MP is the only implant reported in the Michigan Arthroplasty Registry Collaborative Quality Initiative and has a revision rate of 2.28% at 3 years.

CONCLUSION

The MS TKA design has comparable results to traditional TKA designs across several joint registries and 25 studies in the literature.

Decreased Survival of Medial Pivot Designs Compared with Cruciate-retaining Designs in TKA Without Patellar Resurfacing

BACKGROUND

The medial pivot TKA design was introduced in the 1990s. These are fixed-bearing, medial-conforming implants with virtually no translation in the medial part of the knee, in contrast to the flat lateral part of the insert allowing for translation similar to the native knee during flexion and extension. Most primary TKAs performed in Norway and Australia are cruciate-retaining. All of the medial pivot implants in our study are cruciate-sacrificing but without a post-cam mechanism. The medial pivot implant design was developed to more closely mimic native knee motion, in the hope of improving function, and not primarily as a more constrained knee for difficult cases. In the past 10 to 12 years, a second-generation medial-pivot design has emerged, but there are no larger registry studies on the survival of these implants. Both cruciate-retaining and medial pivot designs are reported in the Australian and Norwegian registries, allowing for large-scale, comparative survivorship studies.

QUESTIONS/PURPOSES

(1) Is there any difference in survival between the medial pivot design and the three most commonly used cruciate-retaining TKA designs? (2) Is there any difference in survival among the different medial pivot implant designs? (3) What are the main indications for revision of medial pivot TKAs?

METHODS

Registry data from the Australian Orthopaedic Association National Joint Replacement Registry and Norwegian Arthroplasty Register from 2005 until the end of 2017 were used to compare the five different brands of medial pivot TKA designs (total primary TKAs assessed: 6310). In Australia, the study group of medial pivot implants represented 9% (6012 of 72,477) of the total number of cemented/hybrid TKAs without patellar resurfacing; 345 had cementless femoral components. In Norway, the study group represented 1% (298 of 47,820) of the total number of TKAs with cemented tibias without patellar resurfacing; all had cemented femoral components. The control group consisted of the three most commonly used cruciate-retaining TKA designs (n = 70,870; Australia n = 54,554; Norway n = 16,316). All TKAs used a fixed-bearing, cemented tibial component and did not involve patella resurfacing. Kaplan-Meier survival analysis was assessed to estimate survivorship. We compared the groups by calculating the hazard ratios (HR) using Cox regression adjusted for age, gender and preoperative diagnosis with 95% CI. To answer our third question, we calculated the percentage of each revision indication from the total number of revisions in each group, and used a Cox regression analysis to compare revision causes and HRs. Analyses were performed separately by each registry. Accounting for competing risks (Fine and Gray) did not alter our findings [].

RESULTS

After controlling for potential confounding variables such as gender, age and preoperative diagnosis, we found an increased revision risk for the medial pivot compared with cruciate-retaining TKA designs in Australia (HR 1.4 [95% CI 1.2 to 1.7]; p < 0.001), but not in Norway (HR 1.5 [95% CI 0.9 to 2.4]; p = 0.1). Two brands of the medial pivot design reported to the AOANJRR showed an increased risk of revision compared with cruciate-retaining designs: the Advance® II MP (HR 1.7 [95% CI 1.2 to 2.6]; p = 0.004) and the GMK® Sphere (HR 2.0 [95% CI 1.5 to 2.6]; p < 0.001), whereas the MRK (HR 0.7 [95% CI 0.4 to 1.5]; p = 0.4), the Evolution® MP (HR 1.4 [95% CI 1.0 to 1.9]; p = 0.06) and the SAIPH® (HR 0.9 [95% CI 0.5 to 1.5]; p = 0.7) showed no difference. The most common reasons for revision of medial pivot implants in Australia were infection (27%), pain alone (19%), patellar erosion (13%), loosening/lysis (12%); in Norway the primary indications were loosening/lysis (28%), instability (28%), malalignment (11%) and pain alone (11%).

CONCLUSIONS

The medial pivot TKA design as a group had a higher revision rate than cruciate-retaining fixed-bearing controls in TKA performed without patellar component resurfacing. By brand, the Advance II MP and the GMK Sphere had inferior survivorship, whereas the MRK, the SAIPH and the Evolution MP had no differences in survivorship compared with cruciate-retaining controls. In Australia, TKAs with the medial pivot design without patella resurfacing had a higher rate of revisions for instability, malalignment, and patella erosion. In Norway, there was an increased risk of revision for lysis and loosening compared with the cruciate-retaining design. Several of these implants had short follow-up in this study. Further registry studies with longer follow up are therefore necessary.

LEVEL OF EVIDENCE

Level III, therapeutic study.

A Single Surgeon Series Comparing the Outcomes of a Cruciate Retaining and Medially Stabilized Total Knee Arthroplasty Using Kinematic Alignment Principles

BACKGROUND

Total knee arthroplasty (TKA) designs are developed to optimize kinematics and improve patient satisfaction. The cruciate retaining (CR) and medially stabilized (MS) TKA designs have reported good mid-term follow-up outcomes. However, reasons for consistently high rates of patient dissatisfaction following a TKA remain poorly understood. To further investigate this, we compared the short-term functional outcomes and quality of life, using patient-reported outcome measures (PROMs) and range of motion (ROM), between a CR and MS TKA.

METHODS

A prospective comparison was made between 2 groups (44 CR-TKAs vs 46 MS-TKAs). The Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS-12, KOOS-Short form, KOOS-Joint Replacement, Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index, UCLA Activity Scale, and EuroQuality of life - 5 Dimension were completed preoperatively and 1 year postoperatively. The Forgotten Joint Score (FJS) and Visual Analogue Scale-Satisfaction were completed at 1 year postoperatively. ROM was collected preoperatively and 1 year postoperatively.

RESULTS

Patients who underwent an MS-TKA scored significantly better than the CR-TKA on the FJS (MS = 79.87, CR = 63.8, P = .005), the KOOS-12 Quality of Life subscale (MS = 82.8, CR = 74.4, P = .43), and the KOOS Quality of Life subscale (MS = 82.8, CR = 74.6, P = .44). There was no difference between the groups in all assessed PROMs or ROM, preoperatively and 1 year postoperatively.

CONCLUSION

Patients who underwent the MS-TKA scored significantly better on the FJS and the quality of life subscale of the KOOS and KOOS-12 than those who underwent a CR-TKA. All other assessed PROMs and ROM were comparable between the 2 groups and demonstrated that both implants facilitated symptom relief and improved daily function at 1 year postoperatively. These findings suggest that at short-term follow-up, the MS device is more likely to allow a patient to "forget" that a joint has been replaced and restore their quality of life. Long-term assessment of MS-TKA design outcomes in larger cohorts is recommended.

Total knee arthroplasty using modified measured resection: a five-year retrospective review of midterm outcomes

INTRODUCTION

Deforming arthrosis, or osteoarthritis, is the most common rheumatic disease that involves the musculoskeletal system. The purpose of this research is to perform a retrospective review of the quality of life of patients with knee arthrosis, who underwent total knee arthroplasty (TKA) no less than 5 years ago, to evaluate, based on the Knee Society Scoring System, the efficacy of a modified measured resection technique, and to investigate factors that affect the outcomes.

MATERIAL AND METHODS

The research sample consisted of 44 patients who had severe osteoarthrosis, Kellgren-Lawrence grade III and grade IV.

RESULTS

The post-operative complications occurred in seven knee joints. Among them there were 2 cases of infection, 2 cases of periprosthesis fracture, and 2 cases of aseptic instability, each pair accounting for 4.3%, and 1 case of femoropatellar pain (2.3%). The remaining 38 knee joints (84.8%) were free of complications.

CONCLUSIONS

Knee arthrosis is a serious health problem, given the significant rate of disability among patients and the significant reduction in the quality of life. Patients often seek medical help at the later stages of the disease, when pain is strong and knee function is significantly reduced. The approach to rehabilitation procedures and, in some cases, to lifestyle improvement should be more responsible.

Medial ball and socket total knee arthroplasty: five-year clinical results

AIMS

Between 15% and 20% of patients remain dissatisfied following total knee arthroplasty (TKA). The SAIPH knee system (MatOrtho, Surrey, United Kingdom) is a medial ball and socket TKA that has been designed to replicate native knee kinematics in order to maximize the range of movement, stability, and function. This system is being progressively introduced in a stepwise fashion, with this study reporting the mid-term clinical and radiological outcomes.

PATIENTS AND METHODS

A retrospective review was undertaken of the first 100 consecutive patients with five-year follow-up following SAIPH TKA performed by the senior authors. The data that were collected included the demographics of the patients, clinical findings, the rate of intraoperative ligamentous release, patient-reported outcome measures (PROMS), radiological assessment, complications, and all-cause revision. Revision data were cross-checked with a national registry.

RESULTS

A total of 100 TKAs in 92 patients were included. Three patients died (three TKAs) and a further two TKAs were revised. Of the remaining 95 TKAs, five-year follow-up data were available for 81 TKAs (85%) in 87 patients. There were significant improvements in all PROMs and high satisfaction. The mean ROM at final follow-up was from 0° (full extension) to 124° flexion. There were seven major complications (7%): one infection, two deep vein thromboses, one cerebrovascular event, and two patients with stiffness requiring a manipulation under anaesthesia. Two patients required a lateral retinacular release to optimize patellar tracking in valgus knees; no additional ligament releases were performed in any patient. Radiological analysis demonstrated no evidence of implant-related complications.

CONCLUSION

These results demonstrate satisfactory clinical and radiological outcomes at five years following a medial ball and socket TKA. The complication and revision rates are consistent with those previously reported for patients undergoing TKA. These results demonstrate the safety and efficacy of the SAIPH Knee TKA system and support its wider use.

A Systematic Review of Clinical Functional Outcomes After Medial Stabilized Versus Non-Medial Stabilized Total Knee Joint Replacement

BACKGROUND

Medial stabilized total knee joint replacement (TKJR) construct is designed to closely replicate the kinematics of the knee. Little is known regarding comparison of clinical functional outcomes of patients utilising validated patient reported outcome measures (PROM) after medial stabilized TKJR and other construct designs.

PURPOSE

To perform a systematic review of the available literature related to the assessment of clinical functional outcomes following a TKJR employing a medial stabilized construct design.

METHODS

The review was performed with a Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) algorithm. The literature search was performed using variouscombinations of keywords. The statistical analysis was completed using Review Manager (RevMan), Version 5.3.

RESULTS

In the nineteen unique studies identified, there were 2,448 medial stabilized TKJRs implanted in 2,195 participants, there were 1,777 TKJRs with non-medial stabilized design constructs implanted in 1,734 subjects. The final mean Knee Society Score (KSS) value in the medial stabilized group was 89.92 compared to 90.76 in the non-medial stabilized group, with the final KSS mean value difference between the two groups was statistically significant and favored the non-medial stabilized group (SMD 0.21; 95% CI: 0.01 to 0.41; p = 004). The mean difference in the final WOMAC values between the two groups was also statistically significant and favored the medial stabilized group (SMD: -0.27; 95% CI: -0.47 to -0.07; p = 0.009). Moderate to high values (I2 ) of heterogeneity were observed during the statistical comparison of these functional outcomes.

CONCLUSION

Based on the small number of studies with appropriate statistical analysis, we are unable to reach a clear conclusion in the clinical performance of medial stabilized knee replacement construct.

LEVEL OF EVIDENCE

Level II.

Are Midterm Patient-Reported Outcome Measures Between Rotating-Platform Mobile-Bearing Prosthesis and Medial-Pivot Prosthesis Different? A Minimum of 5-Year Follow-Up Study

BACKGROUND

Both rotating-platform (RP) mobile-bearing and medial-pivot (MP) fixed-bearing prostheses allow axial femorotibial rotation using a highly conforming polyethylene insert. However, limited comparative data are available between the 2 designs. This study was performed to compare the midterm clinical outcomes and patient-reported outcome measures (PROMs) of RP and MP prostheses.

METHODS

We retrospectively reviewed the records of 52 total knee arthroplasties using RP mobile-bearing prosthesis and 49 total knee arthroplasties using MP fixed prosthesis with a minimum follow-up period of 5 years. Clinical and radiological outcomes, failure rates, and PROMs, including the Western Ontario and McMaster Universities Osteoarthritis Index score and satisfaction, were compared.

RESULTS

There was no difference in clinical or radiographic outcomes (P > .1 for all comparisons), with the exception of the larger flexion contracture (FC) in the MP group (0.3° in RP vs 2.3° in MP, P < .01). No failure in either group was recorded during the study period. PROMs were comparable (P > .1 in all comparisons), with the exception of higher satisfactions in the RP group while performing light household duties (P < .01) and leisure or recreational activities (P = .014) in patients without FC.

CONCLUSION

The midterm clinical results with both the RP mobile-bearing and MP fixed-bearing prostheses were satisfactory. Although both prostheses provided comparable PROMs, patients with an RP prosthesis were more satisfied than those with an MP prosthesis for highly demanding activities that are strongly associated with the presence of postoperative FC.

A long term clinical outcome of the Medial Pivot Knee Arthroplasty System

BACKGROUND

The ideal total knee arthroplasty (TKA) should provide maximum range of motion and functional stability for all desired daily activities and, if possible, to replicate normal knee kinematics and function. The ADVANCE® Medial Pivot (AMP) Knee System was designed with a highly congruent medial compartment and a less conforming lateral compartment to more closely mimic the kinematics of the normal knee and to offer more stability through out of range of motion (ROM). The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of this TKA system.

METHODS

Three hundred and twenty-five (325) patients (347 knees) with knee osteoarthritis underwent a TKA using the AMP prosthesis in our Department. For evaluation, objective and subjective clinical rating systems along with radiograph series were used. The average follow-up was 15.2years.

RESULTS

All patients showed a statistically significant improvement (p<0.0005) in the Knee Society clinical rating system, Western Ontario and McMaster Universities Osteoarthritis Index questionnaire, SF-12® questionnaire, and Oxford knee score. The majority of patients (94%) were able to perform age-appropriate activities with a mean knee flexion of 120° (range, 105°-135°) at final follow-up. Survival analysis showed a cumulative success rate of 98.8% at 17years.

CONCLUSION

The obtained results demonstrate excellent long-term clinical outcome for this knee design.

Comparison of ultra-congruent mobile- and fixed-bearing navigation-assisted total knee arthroplasty with minimum 5-year follow-up

PURPOSE

The purpose of this study was to compare the midterm outcomes between fixed and mobile ultra-congruent (UC) bearings in total knee arthroplasty (TKA).

METHODS

This is a retrospective matched-pairs case-control study of patients who underwent primary navigation-assisted TKA with a minimum 5-year follow-up. A total of 182 cases involved the fixed UC bearing system as Group 1 and 101 cases involved mobile UC bearing system group as Group 2. After 1:1 matching, 73 knees in each group were enrolled. Clinical and radiographic outcomes were evaluated.

RESULTS

The overall survival was 143 of 146 cases (97.9 %) at final follow-up, and 72 of 73 cases (96.3 %) in Group 1 and 71 of 73 cases (95.8 %) in Group 2 at final follow-up based on an endpoint of revision surgery. The reasons of revision TKA were periprosthetic fracture in Group 1, infection and bearing dislocation in Group 2. There was no statistical difference in Hospital for Special Surgery (HSS) scores, Knee Society Scores (KSS), WOMAC index score evaluations between groups.

CONCLUSIONS

This study demonstrated that the fixed-bearing UC prosthesis could provide satisfactory performance compared with that of the mobile-bearing UC prosthesis with minimum 5-year follow-up. The fixed-bearing UC prosthesis could be considered in navigation-assisted TKA with theoretical advantages of UC design.

LEVEL OF EVIDENCE

IV.

An 11- to 15-year clinical outcome study of the Advance Medial Pivot total knee arthroplasty

Aims

The Advance Medial-Pivot total knee arthroplasty (TKA) was designed to reflect contemporary data regarding the kinematics of the knee. We wished to examine the long-term results obtained with this prosthesis by extending a previous evaluation.

Patients and Methods

We retrospectively evaluated prospectively collected data from 225 consecutive patients (41 men and 184 women; mean age at surgery 71 years, 52 to 84) who underwent 284 TKAs with a mean follow-up of 13.4 years (11 to 15). Implant failure, complication rate, clinical (both subjective and objective) and radiological outcome were assessed. Pre- and post-operative clinical and radiographic data were available at regular intervals for all patients. A total of ten patients (4.4%; ten TKAs) were lost to follow-up.

Results

Survival analysis at 15 years showed a cumulative success rate of 97.3% (95% confidence interval (CI) 96.7 to 97.9) for revision for any reason, of 96.4% (95% CI 95.2 to 97.6) for all operations, and 98.8% (95% CI 98.2 to 99.4) for aseptic loosening as an end point. Three TKAs (1.06%) were revised due to aseptic loosening, two (0.7%) due to infection, one (0.35%) due to instability and one (0.35%) due to a traumatic dislocation. All patients showed a statistically significant improvement on the Knee Society Score (p = 0.001), Western Ontario and McMaster University Osteoarthritis Index (p = 0.001), Short Form-12 (p = 0.01), and Oxford Knee Score (p = 0.01). A total of 207 patients (92%) were able to perform age appropriate activities with a mean flexion of the knee of 117° (85° to 135°) at final follow-up.

Conclusion

This study demonstrates satisfactory functional and radiographic long-term results for this implant. Cite this article: Bone Joint J 2016;98-B:1050–5.

Medial pivot knee in primary total knee arthroplasty

Total knee arthroplasty (TKA) with a medial pivot design was developed in order to mimic normal knee kinematics; the highly congruent medial compartment implant should improve clinical results and decrease contact stresses. Clinical and radiographic mid-term outcomes are satisfactory, but we need other studies to evaluate long-term results and indications for unusual cases.