Instability after total knee arthroplasty: A systematic review and meta-analysis of treatment options and outcomes.

Background and Hypothesis: Flexion instability is a poorly understood cause of total knee arthroplasty (TKA) failure, often referred to as a “wastebasket” diagnosis for unexplained persistent pain. It remains a challenging diagnosis, with unpredictable outcomes following revision surgery. This study identified predictors of successful patient reported outcome measures (PROMS) following revision for flexion instability. Methods: 121 consecutive revision TKAs for flexion instability from 2011-2018 at a single center were retrospectively reviewed. PROMS were prospectively obtained preoperatively and at minimum one-year follow-up. 33 potential predictors of PROMS encompassed: presenting symptoms, demographics/medical covariates, intraoperative observations, and pre/postoperative radiographic measurements. Variables related to outcomes with p≤0.20 in univariate analysis were entered in regression models. Nonsignificant predictors were pruned until only predictors with p<0.05 and the best model statistics were achieved. Results: The sample was 63% female with mean age of 65±11 and BMI of 34±7 kg/m2. Pre- to postoperative changes in three radiographic measurements vital to the stability and function of TKA were related to function (p<0.001), pain (p=0.019), and satisfaction (p=0.030) after surgery. Pain with walking (p≤0.059) and stair climbing (p≤0.048) were almost exclusively related to demographic/medical covariates. Only one of the presenting symptoms commonly associated with flexion instability influenced early revision outcomes (p=0.021). Conclusion and Potential Impact: Instability is one of the most common reasons for TKA failure leading to costly revision surgery. To our knowledge, this is the largest flexion instability cohort studied to date, including substantially more predictors in an attempt to elucidate factors indicative of successful treatment outcomes. With the exception of radiographic parameters reflecting surgical decisions, findings suggest that many factors related to outcomes may be beyond the control of arthroplasty surgeons.

[This corrects the article DOI: 10.1371/journal.pone.0214279.].

What's New in Hip Replacement.

Reevaluating isolated polyethylene revision for instability after total knee arthroplasty

Highlights of the 2021 American Joint Replacement Registry Annual Report.

What's New in Shoulder and Elbow Surgery.

PurposeProsthesis design influences stability in total knee arthroplasty and may affect maximum knee flexion. Posterior-stabilised (PS) and condylar-stabilised (CS) designed prosthesis do not require a posterior-cruciate ligament to provide stability. The aim of the current study was to compare the range of motion (ROM) and clinical outcomes of patients undergoing cemented total knee arthroplasty (TKA) using either a PS or CS design prosthesis.MethodsA total of 167 consecutive primary TKAs with a CS bearing (mobile deep-dish polyethylene) were retrospectively identified and compared to 332 primary TKA with a PS constraint, with similar design components from the same manufacturer. Passive ROM was assessed at last follow-up with use of a handheld goniometer. Clinical scores were assessed using Patient-Reported Outcome Measures (PROMs); International Knee Society (IKS) knee and function scores and satisfaction score. Radiographic assessment was performed pre and post operatively consisting of mechanical femorotibial angle (mFTA), femoral and tibial mechanical angles measured medially (FMA and TMA, respectively) on long leg radiographs, tibial slope and patella height as measured by the Blackburne-Peel index (BPI).ResultsBoth groups had a mean follow-up of 3 years (range 2–3.7 years). Mean post-operative maximum knee flexion was 117° ± 4.9° in the PS group and 119° ± 5.2° in the CS group (p = 0.29). Postoperative IKS scores were significantly improved in both groups compared to preoperative scores (p < 0.01). The mean IKS score in the PS group was 170.9 ± 24.1 compared to 170.3 ± 22.5 in the CS group (p = 0.3). Both groups had similar radiographic outcomes as determined by coronal and sagittal alignment, tibial slope and posterior condylar offset ratio measurements. When considering the size of tibial slope change and posterior-condylar offset ratio, there was no differences between groups (p = 0.4 and 0.59 respectively). The PS group had more interventions for post-operative stiffness (arthrolysis or manipulation under anaesthesia) 8 (2.7%) compared to 1 (0.6%) in the CS group (p = 0.17).ConclusionCondylar-stabilised TKA have similar patient outcomes and ROM at a mean follow-up of 3 years compared to PS TKA. Highly congruent inserts could be used without compromising results in TKA at short term.Level of evidenceLevel IV, retrospective case control study.

Introduction: The use of modular components provides several advantages in total knee arthroplasty (TKA), including exchange of the polyethylene insert while retaining the stable components in the revision TKA. Compared to full, non-modular component revision TKA, isolated polyethylene exchange (IPE) has the advantage of decreased morbidity, faster rehabilitation, and acceptable outcomes. Methods: A review of published literature on revision TKA was conducted, with a specific focus on studies evaluating the use of IPE for managing complications such as stiffness, instability, and periprosthetic joint infection (PJI). Results: IPE with downsizing may be considered for patients with mild stiffness and stable, well-positioned implants that have increased polyethylene thickness, though expectations for motion gain should be cautious. There is no clear consensus on IPE for instability. Some studies report high re-revision rates, while others show clinical and functional improvement when the TKA is well-aligned, well-fixed, and intraoperative gap balance is achieved. Additionally, irrigation and debridement with polyethylene exchange (IDPE) may be effective for acute TKA PJI management, particularly within the first two weeks of symptom onset. Conclusions: Based on current literature, IPE in aseptic TKA revisions may be effective for stiffness or instability when implants are well-fixed and well-aligned—particularly if polyethylene constraint can be adjusted for instability or downsized for stiffness. The role of IDPE in acute TKA PJI is better defined in the literature, with strong emphasis on its time-sensitive effectiveness—most notably within the first two weeks of symptom onset.

BackgroudThe indications for total knee arthroplasty (TKA) have been expanded to include younger, demanding patients. Some TKA patients expect a return to high-performance activities to restore optimum quality of life. The concept of the medial pivot (MP) TKA is that more natural knee kinematics can be achieved by altering the bearing design. In the present study, we compared the early outcomes of MP TKA with posterior-stabilized (PS) TKA in terms of patient-reported outcomes, function, and performance.MethodsThis randomized study was performed in a high volume joint replacement facility of a tertiary care military hospital. We enrolled 40 patients each in the MP group and PS group and assessed knee flexion, patient-reported outcome (new Knee Society Score [new KSS]), patient performance (Delaware Osteoarthritis Profile Score [DOPS]), and function (Forgotten Joint Score [FJS]) at 2 years after surgery.ResultsCompared to PS group patients, MP group patients had similar patient-reported outcomes assessed by new KSS (satisfaction, expectation, and activity scales) and FJS. MP knee patients had better performance in the timed up and go test (p < 0.026) and self-paced walk test (p < 0.002) of DOPS. The gain in knee flexion (9.3° ± 14°) compared to baseline was significantly greater in the PS group (p < 0.013).ConclusionsWhen assessed by DOPS, getting up from chair and walking speed were significantly better in MP knee patients than in PS knee patients. However, considering the predictable rollback ensured by cam and post, the PS knee produced better knee flexion. Despite these results, patients were equally satisfied with the two designs.

Rotating hinge knee (RHK) implants are a highly constrained prosthesis designed for knee arthroplasty cases involving significant knee instability. RHK systems are often augmented with metaphyseal tibial cones (MTCs). This study investigated structural stability and patient-reported outcomes (PROs) of RHKs with MTC augmentation. All RHKs utilizing MTC were identified at a single institution from 2016 to 2021. Patients returned for radiographic evaluation, physical exam, and PROs. A total of 84 knees (80 patients) were identified, 44 cases (43 patients) followed up greater than 2 years after their RHK procedure. A cumulative incidence function curve was constructed, and failure was defined as a subsequent revision. PROs included Knee Injury Osteoarthritis Outcome Score for Joint Replacement and Patient-Reported Outcome Measurement Information System (PROMIS)-10. Patient Acceptable Symptom State and postoperative rating of improvement scores were collected. Cumulative incidence function all-cause failure (N = 84) was 18% at 2.8 years. The diagnoses for failed cases were infection (6 cases), mechanical failure (1 case), and persistent pain (1 case). The mechanical failure was due to loosening of the femoral component requiring femoral only revision. No follow-up cases (N = 44) demonstrated evidence of loosening at the MTC-RHK interface, median follow-up time of 3.82 years. Mean range-of-motion was 0°-120°. Mean PROs were 61.4 for Knee Injury Osteoarthritis Outcome Score for Joint Replacement, 41.2 for PROMIS Mental Health, and 47.9 for PROMIS Physical Health. Patient Acceptable Symptom State was attained by 68% of follow-up cases and 75% reported moderate or better improvement in their quality of life after their RHK. RHK with MTC augmentation did not reveal any cases of loosening of the MTC with only 1 case of femoral loosening. III.

The aim of our study was to compare and contrast the effects of two types of mobile-bearing total knee arthroplasties (TKA), namely, the cruciate-retaining (CR) and posterior-stabilized (PS) TKAs, on clinical outcomes and in vivo kinematics during stair climbing. The Press-Fit Condylar Sigma rotating platform was used for both CR and PS TKAs. Patient-reported outcomes were assessed using the 2011 Knee Society Score. Quadriceps muscle strength was evaluated by isokinetic dynamometry. In vivo kinematics were evaluated using periodic sagittal plane radiographic images obtained during stair climbing to quantify anteroposterior (AP) tibiofemoral translation, implant flexion and axial rotation angles using image-matching techniques. Outcomes were evaluated in 20 TKAs, which had been undergone with clinical success, including ten knees with CR types and ten knees with PS types. There were no significant differences between the CR and PS TKA groups (p > 0.05) in isometric extensor torque (1.0 ± 0.2 and 1.1 ± 0.6Nm/kg, respectively) or patient-reported score for stair climbing function (4.0 ± 0.5 and 3.8 ± 0.9, respectively). Both types of TKAs showed stable AP translation in the mid range of knee flexion and paradoxical translation in the low range of flexion, with limited rotation, during stair climbing. There were no significant differences between the CR and PS TKA groups (P > 0.05) in anterior translation from 80° to 40° of knee flexion (4.2 ± 1.2 and 3.5 ± 1.6mm, respectively), posterior translation from 40° to 10° of knee flexion (2.3 ± 1.9 and 2.0 ± 1.5mm, respectively), and total external rotation (2.8° ± 4.9° and 0.5° ± 5.0°, respectively). Both CR and PS types of rotating platform mobile-bearing TKAs provided reproducible knee joint kinematics during stair climbing and equivalent clinical outcomes. IV.

Multiple options are available for the tibial insert in total knee arthroplasty (TKA). A systematic review (SR) and network meta-analysis (NMA) to compare available randomized controlled trials (RCTs) could assist with decision making. We aim to show that designs with increased conformity may improve function and satisfaction without an increase in complications though posterior stabilized (PS) inserts will likely have more flexion. A search of MEDLINE, EMBASE, and the Cochrane Library was performed. Studies were limited to RCTs evaluating cruciate retaining (CR), PS, anterior stabilized (AS), medial pivot (MP), bicruciate retaining (BR), and bicruciate stabilizing (BCS) inserts. Mean differences (MD) were used for patient reported outcome measures (PROMs) and odds ratios (OR) for reoperation rates and MUA. A systematic review was performed for satisfaction. 27 trials were identified. The NMA showed no difference from a statistical or clinical standpoint for PROMs evaluated. There was a statistical difference for increased flexion for PS knees (3 degrees p 0.04). There were no differences in the MUA or reoperation rates. There was insufficient information to determine if a specific insert improved satisfaction. The results of this NMA show no statistical or clinical difference in PROMs. There was higher flexion for PS knees though the amount was not clinically significant. There was insufficient data for conclusions on patient satisfaction. Therefore, the surgeon should evaluate the clinical situation to determine the best insert rather than choose and insert based on functional scores, patient satisfaction, or complication rates.

Postoperative patient satisfaction is related to preoperative expectations. Information regarding expected results following surgery is therefore important. This study evaluated patient-reported outcome measures (PROMs) and patient satisfaction up to 1 year after primary and aseptic revision total knee arthroplasty (TKA). The study included 2151 primary and 235 aseptic revision TKA surgeries conducted between 2010 and 2018. Pain, Knee Injury and Osteoarthritis Outcome Score-Physical Function-Short Form and European Quality of Life-5 Dimension surveys were recorded preoperatively and at 8 weeks and 1 year. To determine satisfaction, patients were asked to rate their knee function compared with that before surgery and to answer whether they would undergo the surgery again given their current knowledge. Patients who had primary TKA improved in all PROMs in each follow-up up to 1 year, whereas patients who had revision TKA showed improvement at 8 weeks with no further improvement at 1 year. In terms of patient satisfaction, 88% of patients in the primary TKA group reported better knee function, and 87% were willing to have the surgery again at 1 year; the proportions were lower for patients who underwent revision TKA (66% and 68%, respectively). Aseptic revision TKA demonstrates inferior PROMs compared with those of primary TKA 1 year after surgery, and more than 30% of the patients who underwent revision TKA stated that they would not have their TKA revised or were uncertain, given the outcome of the procedure. Thus, patients who are candidates for revision TKA should be informed to expect less of an improvement following revision surgery than with the primary TKA. Our findings can facilitate the shared decision-making process by surgeons and patients based on realistic expectations of surgical outcomes. [Orthopedics. 2023;46(1):e52-e57.].

Challenging the Status Quo: Debunking the Necessity of 5-Year to 10-Year Patient-Reported Outcome Measures in Total Hip and Knee Arthroplasties

Background: Rotating-hinge knee (RHK) implants are an option for knee arthroplasty in cases of instability or severe bone loss. However, the revision rate can be increased compared to unconstrained implants which mandate improvements in implant design. This study investigates a novel RHK design for total knee arthroplasty (TKA). Methods: Retrospective analysis of a single design RHK TKA (GenuX MK, Implantcast) implanted between 2015 and 2019 including 133 patients (21 primary TKA, 112 revisions). The main indication for revision TKA was second-stage reimplantation following infection. The median follow-up amounted to 30 months (IQR 22–47). Results: In total, 13% (18/133) of patients underwent revision surgery after a mean time of 1 month (IQR 0–6). The main reason for the revision was (re-) infection in 8% of patients. All revisions were performed following revision TKA and none following primary TKA. There were no revision surgeries for loosening or instability. The revision-free implant survival of 83% was (95% CI 75–91%) after five years. A higher number of previous surgeries was associated with a greater revision risk (p = 0.05). Conclusion: Revision and complex primary TKA using a single-design RHK implant results in good implant survival at mid-term follow-up although infection remains a major concern.