Medial stabilised total knee arthroplasty achieves comparable clinical outcomes when compared to other TKA designs: a systematic review and meta-analysis of the current literature

Predictors of improved and decreased range of motion after medial pivot total knee arthroplasty: A multicenter retrospective analysis

Introduction

No study has identified predictors of improvement and decrease in postoperative range of motion (ROM) after medial pivot (MP) total knee arthroplasty (TKA) compared to preoperative ROM. This multicenter study aimed to identify predictors of improved postoperative range of motion (ROM) after MP-TKA.

Methods

The study included 107 consecutive patients who underwent MP-TKA for knee osteoarthritis at six different centers. Data on patient age, gender, hip knee angle, and pre- and postoperative ROM in extension and flexion were collected. A 9° improvement or decrease in postoperative knee flexion was considered positive. Patients were divided into three groups according to whether knee flexion improved by more than 9° (group I; 35 patients), changed within the minimal clinically important difference (MCID) (group M; 54 patients), or decreased by more than 9° (group D; 18 patients) one year after surgery.

Results

Significant differences in preoperative ROM for flexion were observed between the groups (P < 0.001). Multivariate and receiver operating characteristic (ROC) curve analyses revealed that preoperative flexion less than 118.0° (area under the curve (AUC): 0.957, 95 % confidence interval (CI): 0.924-0.990) was a significant positive prognostic factor for improved postoperative ROM one year postoperatively (odds ratio (OR): 0.75, 95 % CI: 0.66-0.85, P < 0.001) and that preoperative flexion greater than 128.0° (AUC: 0.899, 95 % CI: 0.836-0.961) was a significant positive prognostic factor for decreased postoperative ROM one year postoperatively (OR: 1.14, 95 % CI: 1.07-1.22, P < 0.001).

Discussion

The results showed that a preoperative knee flexion ROM of less than 118° was a significant positive predictor of an improvement in knee flexion ROM of MCID or greater after MP-TKA, and a knee flexion ROM of 128° or greater was a significant positive predictor of a decrease in knee flexion ROM of MCID or greater one year after surgery.

Low-constraint insert with a medial pivot design as a potential predictor of favourable outcomes in cruciate-retaining total knee arthroplasty: A propensity score-matched analysis

PURPOSE

The influence of polyethylene insert conformity on the outcomes of cruciate-retaining (CR) total knee arthroplasty (TKA) with a medial pivot design remains uncertain. Therefore, this study aimed to evaluate the effects of polyethylene insert conformity in CR-TKA on patient-reported outcomes.

METHODS

The data of 255 knees (FINE Total Knee System) from 255 patients were retrospectively analysed to compare outcomes for high- or low-constraint medial pivot inserts, as determined through historical controls, over an average follow-up period of 2.2 years (range, 2.0-5.5 years). Multivariate logistic regression analysis was used to identify predictors of achieving the patient-acceptable symptom state (PASS) for the Forgotten Joint Score-12 (FJS-12). Propensity score-matched cohorts for age, sex, body mass index, Kellgren-Lawrence grade, Charlson Comorbidity Index, knee flexion contracture, FJS-12 and follow-up duration were created for between-group comparison (n = 50 in each group).

RESULTS

Low-constraint insert (p = 0.031) and age (p = 0.043) were independent predictors of achieving the PASS for the FJS-12 (>33, 153/255). After successful matching, compared to the high-constraint insert, the low-constraint insert improved patient satisfaction (p = 0.029 for pain on going up or downstairs, and p = 0.047 for the function of going upstairs) and increased the likelihood of achieving the minimal clinically important difference (p = 0.019) and PASS (p = 0.025) for the FJS-12. A significant correlation was observed between the posterior tibial slope and the FJS-12 in the low-constraint insert group (p < 0.001), indicating that a greater posterior tibial slope was associated with better functional outcomes in this group.

CONCLUSIONS

Compared with high-constraint inserts, low-constraint medial pivot inserts yielded higher functional outcomes and patient satisfaction. Therefore, insert conformity may play a crucial role in CR-TKA outcomes.

LEVEL OF EVIDENCE

Level III.

Comparative study of outcomes with total knee arthroplasty: medial pivot prosthesis vs posterior stabilized implant. Prospective randomized control

PURPOSE

Total knee arthroplasty (TKA) is an effective procedure for pain relief and restoration of function in patients with symptomatic end-stage knee arthritis. Kinematic problems due to conventional implant design have been postulated. The objective of this study is to determine if there was any difference in postoperative ROM and outcomes between patients undergoing MP-TKA vs PS-TKA.

METHODS

We prospectively colected the records of 600 consecutive patients with TKA performed by six senior orthopaedic surgeons between 2017 - 2021. We compared the ROM and patient-reported outcomes (Western Ontario McMaster Osteoarthritis Index WOMAC, Oxford Knee Score OKS, Knee Society Score KSS, Forgotten Joint Score FJS) between MP TKA and PS TKA.

RESULTS

There were no specific criteria for implant selection as the two groups were consecutive cohorts of patients and implant selection depended on surgeon preference. Demographics, comorbidities, diagnosis and severity of osteoarthritis were similar between MP and PS groups. The trend for OKS in our study is the same in both groups, but with higher mean values in the MP group. The trend of WOMAC pain, stiffness and disability score is the same in both groups, but with higher mean values in the PS group at one year and two years. KSS clinical and functional score is the same in both groups, but with higher mean values in the MP group. The most important score is forgetten joint score which is favourable for the MP group.

CONCLUSION

The patients who underwent the MP-TKA scored better than those who underwent the PS-TKA, particularly regarding deep knee flexion and stability of the prosthesis. This may be related to better replication of natural knee kinematics with MP-TKA.

Medial-pivot design does not provide superior clinical results compared to posterior-stabilized total knee arthroplasty despite kinematic differences during step-up and lunge activities: A prospective randomized controlled trial under medial tight soft tissue balance

PURPOSE

This study aimed to compare in vivo kinematics during weight-bearing daily activities and determine the relationship with clinical outcomes in patients undergoing total knee arthroplasty (TKA) with a medial-pivot (MP, Evolution™) versus a posterior-stabilized (PS, Persona®) design under constant conditions of intraoperative soft tissue balance.

METHODS

Forty patients undergoing MP or PS-TKA under similar conditions of soft tissue balance were enrolled in this prospective randomized controlled trial. Outcome measures included clinical knee society scores (KSS) and knee injury and osteoarthritis outcome scores (KOOS). A kinematic assessment was conducted while the participants performed lunge and step-up activities under fluoroscopic guidance.

RESULTS

Eighteen patients in each arm completed 1-year follow-up and were included in the analysis. All patients experienced pain relief and satisfactory knee function postoperatively. In kinematics, in the MP arm, the medial femoral condyle remained consistent, whereas the lateral femoral condyle gradually shifted posteriorly with increasing knee flexion. Conversely, in the PS arm, paradoxical anterior movement of the medial femoral condyle accompanied the lateral pivot motion. During lunge and step-up activities, a medial-pivot motion was observed in 83% and 72% of knees in the MP arm, respectively, compared with 22% and 11% in the PS arm. Despite these differences in kinematics, there were no statistically significant differences in the KSS and KOOS between the two groups.

CONCLUSION

Under weight-bearing conditions during flexion, knees that underwent Evolution™ MP-TKA did not show superior clinical results compared to Persona® PS-TKA, despite exhibiting in vivo kinematics closely resembling the normal in vivo pattern.

LEVEL OF EVIDENCE

Level I, therapeutic studies.

Kinematic Alignment Achieves a More Balanced Total Knee Arthroplasty Than Mechanical Alignment among CPAK Type I Patients: A Simulation Study

Background: There is no consensus on whether mechanical alignment (MA) or kinematic alignment (KA) should be chosen for total knee arthroplasty (TKA) for coronal plane alignment of the knee (CPAK) Type I with a varus arithmetic HKA (aHKA) and apex distal joint line obliquity (JLO). The aim of this study was to investigate whether MA or KA is preferable for soft tissue balancing in TKA for this phenotype. Method: This prospective cohort study included 64 knees with CPAK Type I osteoarthritis that had undergone cruciate-retaining TKA. Using optical tracking software, we simulated implant placement in the Mako system before making the actual bone cut and compared the results between MA and KA. Extension balance (the difference between medial and lateral gaps in extension) and medial balance (the difference in medial gaps in flexion and extension) were examined. These gap differences within 2 mm were defined as good balance. Achievement of overall balance was defined as an attainment of good extension and medial balance. The incidence of balance in each patient was compared with an independent sample ratio test. Results: Compared with the MA group, the KA group achieved better soft tissue balance in extension balance (p < 0.001). A total of 75% of the patients in the KA group achieved overall balance, which was greater than the 38% achieved in the MA group (p < 0.001). Conclusions: In robot-assisted TKA for CPAK Type I osteoarthritis, KA achieved knee balance during extension without soft tissue release in a greater percentage of patients than MA.

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

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.

Comparison of postoperative clinical outcome in medial-pivotal and gradually reducing radius design cruciate-retaining total knee arthroplasty-A multicenter analysis of propensity-matched cohorts

Purpose

To clarify differences in surgery duration, postoperative knee range of motion (ROM), anterior and posterior (AP) laxity, and Forgotten Joint Score (FJS) in patients undergoing medial-pivot (MP) and GRADIUS cruciate-retaining (CR) total knee arthroplasty (TKA) surgeries.

Methods

We examined patients who underwent either MP or CR TKA at six different Japanese centres. Patients were propensity score matched for age, sex, and preoperative hip-knee angle (HKA). We compared the groups' average surgery duration, postoperative knee ROM, AP laxity, and FJS 1 year after surgery.

Results

There were 86 study patients: 43 MP and 43 CR TKA matched for age, sex, and preoperative HKA. The MP group enjoyed a significantly shorter surgery duration (89.1 ± 10.9 mins vs. 95.7 ± 12.0 mins, p = 0.0091) and significantly better postoperative knee flexion than the CR group (123.7 ± 9.1° vs. 115.3 ± 12.4°, p < 0.001). The MP had significantly smaller postoperative AP laxity with 30° of knee flexion than the CR group (3.4 ± 1.3 vs. 5.6 ± 2.2 mm, p < 0.001). Conversely, postoperative AP laxity with 90° of knee flexion was significantly larger for the MP group (3.6 ± 1.3 vs. 2.7 ± 1.9 mm, p = 0.0098). There were no between-group differences in postoperative FJS.

Conclusions

The MP group showed better postoperative knee flexion, midrange AP knee stability, and shorter surgery duration.

Level of Evidence

Level III, retrospective comparative study.

Predicting outcomes after total knee arthroplasty using intraoperative knee kinematics measured by navigation

OBJECTIVES

The objective of the study is to evaluate the relationship between clinical results following posterior-stabilized total knee arthroplasty (TKA) and intraoperative kinematic pattern determined from navigation.

METHODS

Participants were patients with knee osteoarthritis and varus deformity who underwent primary posterior-stabilized TKA. Preoperative and post-implantation kinematic data were recorded, and all kinematic patterns were divided into two types: medial pivot (MP) or non-MP. Knees with MP and non-MP patterns after implantation were compared in terms of postoperative flexion angle, pain, patient satisfaction, expectations, and activity using the new Knee Society Score 2011 at 1 year postoperatively.

RESULTS

This study involved 55 patients (12 men, 43 women) with a mean age of 73.1 years and mean body mass index of 26.5 kg/m2. Preoperative kinematic measurements showed MP in 23 knees and non-MP in 32 knees. After implantation, navigation showed MP in 25 knees and non-MP in 30 knees. No significant differences were found between kinematic patterns preoperatively and after implantation. Postoperative flexion angle, pain, patient satisfaction, expectations, and activity using Knee Society Score 2011 showed no differences between MP and non-MP knees.

CONCLUSION

Intraoperative knee kinematics as measured by navigation could not predict postoperative outcomes of TKA.

Medial pivot design does not yield superior results compared to posterior-stabilised total knee arthroplasty: a systematic review and meta-analysis of randomised control trials

PURPOSE

The aim of this meta-analysis was a comparison between medial pivot (MP) and posterior-stabilised (PS) knee designs regarding functional and radiological outcomes as well as gait parameters.

METHODS

A systematic literature search was conducted in PubMed, Cochrane Library, Science Direct and Clinical Trials.gov from conception up to April 2022, to identify eligible randomised control trials (RCTs). The extracted data were analysed according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement.

RESULTS

Fifteen studies met inclusion criteria, enrolling 1101 patients who underwent 1242 total knee arthroplasties (TKAs). A total of 1158 TKAs (581 MP/577 PS) were included in the quantitative analysis. Mean follow-up ranged from 6 months up to 6.6 years. MP knees showed comparable range of motion (ROM) with PS design 1, 2 and 4 years postoperatively (p = 0.2, p = 0.25, p = 0.34, respectively). No statistical difference was found in patient-related outcome measures (PROMs) (p > 0.05). Mean walking speed (MWS), length of stay (LOS), radiographic alignment and complications rates were also similar between the two groups (p > 0.05).

DISCUSSION

The present meta-analysis demonstrated that the theoretical biomechanical advantage of MP implants does not have a better impact on patient satisfaction compared to the traditional PS knees.

LEVEL OF EVIDENCE

I.

Medial stability and lateral flexibility of the collateral ligaments during mid-range flexion in medial-pivot total knee arthroplasty patients demonstrates favorable postoperative outcomes

PURPOSE

The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA).

METHODS

Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group. The attachment sites of the sMCL and LCL were marked to calculate the 3D wrapping length. The sMCL and LCL were divided into anterior, intermediate, and posterior portions (aMCL, iMCL, pMCL, aLCL, iLCL, pLCL). Correlations between lengths/elongation rate of ligament bundles from full extension to 100° flexion and the KSS were examined.

RESULTS

The sMCL and LCL demonstrated relative stability in length at low flexion, but sMCL length decreased whereas LCL increased with further flexion on operated knees. The sMCL length increased at low flexion and remained stable with further flexion, while the LCL length decreased with flexion on the contralateral non-operated knees. The lengths of aMCL, iMCL, and pMCL showed moderate (0.5 < r < 0.7, p < 0.05) negative correlations with the KSS, and the lengths of aLCL, iLCL, and pLCL were positively correlated with the KSS at mid flexion on operated knees (p < 0.05). The elongation rates of aLCL, iLCL, and pLCL were negatively correlated with the KSS at high flexion on operated knees (p < 0.05). However, no significant correlations between the length of different bundles of sMCL or LCL with KSS were found on contralateral non-operated knees.

CONCLUSIONS

The elongation pattern of sMCL/LCL on MP-TKA knees showed differences with contralateral non-operated knees. The sMCL is tense at low to middle flexion and relaxed at high flexion, while LCL is relaxed at low to middle flexion and tense at high flexion following MP-TKA. Medial stability and proper lateral flexibility during mid flexion were associated with favorable postoperative outcomes in MP-TKA patients. In contrast, lateral relaxation at deep flexion should be avoided when applying soft-tissue balancing in MP-TKA.

LEVEL OF EVIDENCE

Level III.

Better flexion and early recovery with medial-stabilized vs single-radius total knee arthroplasty with kinematic alignment: Two-year clinical results

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.

Long-Term Follow-Up of Medial Pivot Total Knee Arthroplasty: A Systematic Review of the Current Evidence

Total knee arthroplasty (TKA) is a popular treatment for end-stage knee osteoarthritis. Advances in understanding knee biomechanics have led to the development of medial pivot (MP) prostheses, which aim to replicate natural knee kinematics. While short- and mid-term studies have shown favorable outcomes for MP-TKA, long-term follow-up studies are limited. This systematic review aims to analyze the available evidence on long-term outcomes of MP-TKA, including survivorship, complications, and patient-reported outcome measures (PROMs). A comprehensive search was conducted in PubMed, Embase, and Cochrane Database of Systematic Reviews for English language studies reporting long-term outcomes of primary MP-TKA. Nine studies with an average follow-up of 12.4 years were included. Data on survivorship, complications, and PROMs were collected and analyzed. The overall survivorship of MP-TKA was 98.2% at an average follow-up of 12.4 years. Aseptic loosening and periprosthetic joint infection (PJI) were the most common reasons for revision, with a revision rate of 0.4% for each. The overall complication rate was 6.6%, with secondary anterior knee pain and PJI being the most frequent complications. The reoperation rate was 3.1%, primarily due to PJI and knee instability. PROMs significantly improved postoperatively. MP-TKA demonstrates favorable long-term outcomes with high survivorship, low complication rates, and enhanced PROMs. The procedure provides reliable management for end-stage osteoarthritis, offering patients improved knee function and pain relief. Further research with standardized reporting and larger sample sizes is needed to validate and compare these findings to other implant designs.

Medial Pivot Designs Versus Conventional Bearing Types in Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Medial pivot (MP) designs are growing in popularity. They provide increased sagittal plane stability and theoretically replicate some aspects of native joint kinematics, which may improve total knee arthroplasty outcomes.

METHODS

A systematic review was performed of randomized controlled trials (RCTs) that compared MP designs with cruciate-retaining, posterior-stabilized (PS), ultracongruent, or mobile-bearings in primary total knee arthroplasty, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome measures were all clinical function scores, patient-reported outcome measures, and range of motion. The secondary outcome was complications. Two authors independently selected studies, performed data extraction, and risk-of-bias assessment. Studies at high risk of bias were excluded from meta-analysis. Treatment effects were assessed using random-effects meta-analysis and quantified using pooled mean differences or incidence rate differences as appropriate.

RESULTS

Eight RCTs met inclusion criteria. Five compared MP with PS, two with ultracongruent, and one with cruciate-retaining and mobile-bearing. In total, 350 knees were randomized to MP and 375 to conventional bearings. One RCT was excluded from meta-analysis because of high risk of bias. Meta-analysis comparing MP with PS only was possible and found no differences at any time points for any outcome measure, including 2-year follow-up for Oxford Knee Score (MD = 0.35 favoring PS; 95% CI -0.49 to 1.20) and range of motion (MD = 1.58 favoring MP; 95% CI -0.76 to 11.92, P = 0.30) and 12 months for Western Ontario Arthritis Index (MD = 4.42 favoring MP; 95% CI -12.04 to 3.20, P = 0.09).

CONCLUSIONS

There is no difference in clinical outcomes, with contemporary measurement tools, at any time points, between MP and PS. There are insufficient RCTs comparing MP with other bearings.

Kinematic function of knee implant designs across a range of daily activities

The aim of this randomized controlled trial was to measure and compare six-degree-of-freedom (6-DOF) knee joint motion of three total knee arthroplasty (TKA) implant designs across a range of daily activities. Seventy-five TKA patients were recruited to this study and randomly assigned a posterior-stabilized (PS), cruciate-retaining (CR), or medial-stabilized (MS) implant. Six months after surgery, patients performed five activities of daily living: level walking, step-up, step-down, sit-to-stand, and stand-to-sit. Mobile biplane X-ray imaging was used to measure 6-DOF knee kinematics and the center of rotation of the knee in the transverse plane for each activity. Mean 6-DOF knee kinematics were consistently similar for PS and CR, whereas MS was more externally rotated and abducted, and lateral shift was lower across all activities. Peak-to-peak anterior drawer for MS was also significantly lower during walking, step-up, and step-down (p < 0.017). The center of rotation of the knee in the transverse plane was located on the medial side for MS, whereas PS and CR rotated about the lateral compartment or close to the tibial origin. The kinematic function of MS was more similar to that of the healthy knee than PS and CR based on reduced paradoxical anterior translation at low flexion angles and a transverse center of rotation located in the medial compartment. Overall, 6-DOF knee joint motion for PS and CR were similar across all daily activities, whereas that measured for MS was appreciably different. The kinematic patterns observed for MS reflects a highly conforming medial articulation in the MS design.

Current Trends in Knee Arthroplasty: Are Italian Surgeons Doing What Is Expected?

OBJECTIVES

The purpose of this study is to evaluate Italian surgeons' behavior during knee arthroplasty.

MATERIALS AND METHODS

All orthopedic surgeons who specialized in knee replacement surgeries and were members of the Italian Society of Knee, Arthroscopy, Sport, Cartilage and Orthopedic Technologies (SIGASCOT) between January 2019 and August 2019 were asked to complete a survey on the management of knee arthroplasty. Data were collected, analyzed, and presented as frequencies and percentages.

RESULTS

One-hundred and seventy-seven surgeons completed the survey and were included in the study. Ninety-five (53.7%) surgeons were under 40 years of age. Eighty-five surgeons (48%) worked in public hospitals and 112 (63.3%) were considered "high volume surgeons", with more than 100 knee implants per year. Postero-stabilized total knee arthroplasty was the most commonly used, implanted with a fully cemented technique by 162 (91.5%) surgeons. Unicompartmental knee arthroplasty (UKA) was a rarer procedure compared to TKA, with 77% of surgeons performing less than 30% of UKAs. Most common TKA pre-operative radiological planning included complete antero-posterior (AP) weight-bearing lower limb radiographs, lateral view and patellofemoral view (used by 91%, 98.9% and 70.6% of surgeons, respectively). Pre-operative UKA radiological images included Rosenberg or Schuss views, patellofemoral view and magnetic resonance imaging (66.1%, 71.8% and 46.3% of surgeons, respectively). One hundred and thirty-two surgeons (74.6%) included an AP weight-bearing lower limb X-ray one year after surgery in the post-operative radiological follow-up. Furthermore, 119 surgeons (67.2%) did not perform a post-operative patellofemoral view because it was not considered useful for radiological follow-up. There was no uniformity in the timing and features of post-operative follow-up, with 13 different combinations.

CONCLUSIONS

Italian surgeons perform TKA more commonly than UKA. Pre-operative TKA planning is quite uniform rather than UKA planning. Despite literature evidence, there is no agreement on follow-up. It may be useful to create a uniform checklist, including correct timing and exams needed. This analysis is also part of a society surgical educational project for training doctor.

Medial pivot prosthesis has a better functional score and lower complication rate than posterior-stabilized prosthesis: a systematic review and meta-analysis

Purpose

We aimed to compare the postoperative clinical efficacy and safety of medial pivot (MP) prosthesis and posterior-stabilized (PS) prosthesis in the treatment of knee osteoarthritis (KOA).

Methods

All studies involving MP and PS prosthesis in PubMed, EMBASE, Cochrane Library, and Web of Science were searched since the establishment of the database. The included outcomes were knee range of motion (ROM), functional score, radiographic results, complication rate, and revision rate. Studies were independently evaluated by the Newcastle–Ottawa Scale for case–control studies and the assessment tool of the Cochrane Collaboration for randomized controlled trials. I² was used to test the heterogeneity, and fixed- or random-effects models were selected for meta-analysis according to the heterogeneity results.

Results

A total of 19 studies, consisting of 3592 patients and 3783 knees (MP: 1811 knees, PS: 1972 knees), were included in the meta-analysis. The WOMAC (MD = − 1.11, 95% CI − 1.98 to − 0.23; P = 0.01) and HSS (MD = − 4.32, 95% CI − 8.30 to − 0.34; P = 0.03) in the MP group were significantly lower compared with the PS group, and the complication rate (OR 0.53, 95% CI 0.33–0.87; P = 0.01) was also lower compared with the PS group. There was no significant difference in ROM, radiographic results, and revision rate between the two groups (P > 0.5).

Conclusions

The existing literature provided evidence to support better clinical effect and lower complication rate of MP prosthesis compared to PS prosthesis. These results provide a reference for clinicians when choosing a suitable prosthesis.

Suture tape augmentation ACL repair, stable knee, and favorable PROMs, but a re-rupture rate of 11% within 2 years

PURPOSE

The aim of this study is to investigate clinical and magnetic resonance imaging (MRI) outcomes after anterior cruciate ligament (ACL) repair using the suture tape augmentation (STA) technique.

METHODS

This prospective interventional case series included 35 patients who underwent STA ACL repair and were all followed up for 2 years. The ACL rupture was between 4 and 12 weeks old and per-operatively confirmed repairable. The International Knee Documentation Committee (IKDC), and Lysholm and Tegner scores were collected together with return to work (RTW), return to sport (RTS), re-rupture, and re-intervention rate. Lachman testing was performed and ACL healing was evaluated on MRI using a grading scale based on the ACL's morphology and signal intensity with grade 1 representing good ACL healing and grade 3 representing poor ACL healing.

RESULTS

The number of patients who returned to their pre-rupture level for IKDC, Lysholm, and Tegner scores at 2 years of follow-up are 17/26 (65.4%), 13/25 (52.0%), and 18/27 (66.7%) patients, respectively. Median RTW and RTS periods were 5.5 weeks (range 0-32 weeks) and 6 months (range 2-22 months), respectively. The Lachman side-to-side difference decreased significantly (P < 0.001) to less than 3 mm after surgery and remained stable. Four patients [11.4%, 95% CI (3.2, 26.7)] suffered from a re-rupture and three other patients [8.6%, 95% CI (1.8, 23.1)] needed a re-intervention for another reason than re-rupture. MRI follow-up of 31 patients showed overall grade 1 ACL healing in 14 (45.2%) patients, grade 2 ACL healing in 11 (35.5%) patients, and grade 3 ACL healing in 6 (19.4%) patients. A higher risk of re-rupture was associated with grade 3 ACL healing at 6 months post-operatively and a pre-operative Tegner score of  ≥  7.

CONCLUSION

This study shows that treatment of the acute, repairable ACL with the STA technique leads to a stable knee and favorable patient-reported outcome measures (PROMs). However, the re-rupture rate of 11.4% within the 2-year follow-up is a concern.

LEVEL OF EVIDENCE

IV.

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.