Medial compartment knee osteoarthritis: age-stratified cost-effectiveness of total knee arthroplasty, unicompartmental knee arthroplasty, and high tibial osteotomy

Evaluation of changes in fixed flexion deformity following medial unicompartmental knee arthroplasty

Aims

While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes.

Methods

This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected.

Results

Overall, the median preoperative navigated (NAV) FFD measured 6.0° (IQR 3.1 to 8), while the median postoperative NAV FFD was 3.0° (IQR 1° to 4.4°), representing a mean correction of 49.2%. The median preoperative clinical FFD was 5° (IQR 0° to 9.75°) for the entire cohort, which decreased to 3.0° (IQR 0° to 5°) and 2° (IQR 0° to 3°) at six weeks and one year postoperatively, respectively. A statistically significant improvement in PROMs compared with baseline was evident in all groups (p < 0.001). Regression analyses showed that participants who experienced a larger FFD correction, showed greater improvement in PROMs (β = 0.609, p = 0.049; 95% CI 0.002 to 1.216).

Conclusion

This study found that UKA was associated with an approximately 50% improvement in preoperative FFD across all three examined groups. Participants with greater correction of FFD also demonstrated larger OKS gains. These findings could prove a useful augment to clinical decision-making regarding candidacy for UKA and anticipated improvements in FFD.

Learning curves for high tibial osteotomy using patient-specific instrumentation: a case control study

Objectives

Three-dimensional (3D) planning and Patient Specific Instrumentation (PSI) can help the surgeon to obtain more predictable results in Medial Opening Wedge High Tibial Osteotomy (mOW-HTO) than the conventional techniques. We compared the accuracy of the PSI and standard techniques and measured the learning curve for surgery time and number of fluoroscopic shots.

Methods

We included the first 12 consecutive cases of mOW-HTO performed with 3D planning and PSI cutting guides and the first 12 non-supervised mOW-HTO performed with the standard technique. We recorded surgery time and fluoroscopic time. We calculated the variation (Δ delta) between the planned target and the postoperative result for Hip Knee Ankle Angle (HKA), mechanical medial Proximal Tibia Angle (MPTA), Joint Line Convergence Angle (JLCA) and tibial slope (TS) and compared it both groups. We also recorded the complication rate. We then calculated the learning curves for surgery time, number of fluoroscopic shots, Δ from target in both groups. CUSUM analysis charts for learning curves were applied between the two groups.

Results

Mean surgical time and mean number of fluoroscopic shots were lower in PSI group (48.58±7.87 vs. 58.75±6.86 min; p=0.034 and 10.75±3.93 vs. 18.16±4.93 shots; p<0.001). The postoperative ΔHKA was 0.42±0.51° in PSI vs. 1.25±0.87° in conventional, p=0.005. ΔMPTA was 0.50±0.67° in PSI vs. 3.75±1.48° in conventional, p<0.001; ΔTS was 1.00±0.82° in PSI vs. 3.50±1.57° in conventional, p<0.001. ΔJLCA was 1.83±1.11° in PSI vs. 4±1.41° in conventional, p<0.001. The CUSUM analysis favoured PSI group regarding surgery time (p=0.034) and number of shots (p<0.001) with no learning curve effect for ΔHKA, ΔMPTA, ΔJLCA and ΔTS.

Conclusions

PSI cutting guides and 3D planning for HTO are effective in reducing the learning curves for operation time and number of fluoroscopic shots. Accuracy of the procedure has been elevated since the first cases.

Comparison of short-term clinical outcomes between open-wedge high tibial osteotomy and tibial condylar valgus osteotomy

BACKGROUND

This study aimed to compare radiological features and short-term clinical outcomes between open-wedge high tibial osteotomy (OWHTO) and tibial condylar valgus osteotomy (TCVO), to provide information facilitating decision-making regarding those two procedures.

METHODS

Twenty-seven cases involving 30 knees that had undergone OWHTO (HTO group) and eighteen cases involving 19 knees that had undergone TCVO (TCVO group) for medial compartment knee osteoarthritis (OA) were retrospectively evaluated. Patient characteristics, severity of knee OA, lower limb alignment, joint congruity and instability were measured from standing full-length leg and knee radiographs obtained before and 1 year after surgery. Range of motion in the knee joint was measured and Knee Injury and Osteoarthritis Outcome Score (KOOS) was obtained to evaluate clinical results preoperatively and 1 year postoperatively.

RESULTS

Mean age was significantly higher in the TCVO group than in the HTO group. Radiological features in the TCVO group included greater frequencies of advanced knee OA, varus lower limb malalignment, higher joint line convergence angle, and varus-valgus joint instability compared to the HTO group before surgery. However, alignment of the lower limb and joint instability improved to comparable levels after surgery in both groups. Maximum flexion angles were significantly lower in the TCVO group than in the HTO group both pre- and postoperatively. Mean values in all KOOS subscales recovered similarly after surgery in both groups, although postoperative scores on three subscales (Symptom, Pain, and ADL) were lower in the TCVO group (Symptom: HTO, 79.0; TCVO, 67.5; Pain: HTO, 80.5; TCVO, 71.1; ADL: HTO, 86.9; TCVO, 78.0).

CONCLUSIONS

Both osteotomy procedures improved short-term clinical outcomes postoperatively. TCVO appears preferable in cases of advanced knee OA with incongruity and high varus-valgus joint instability. An appropriate choice of osteotomy procedure is important to obtain favorable clinical outcomes.

Finite Element Analysis of the Effect of Femoral Prosthesis Varus and Valgus Angle Installation on the Lateral Compartment in Unicompartmental Knee Arthroplasty

BACKGROUND

This study used finite element analysis (FEA) to investigate the effect of varus and valgus angle on the lateral compartment in unicompartmental knee arthroplasty (UKA).

METHODS

One patient who underwent UKA was enrolled as the subject. Thirteen working conditions of the femoral prosthesis were simulated at varus and valgus angles of 0°, 2°, 4°, 6°, 8°, 10°, and 12°. A load of 1,000 N was applied downward along the mechanical axis of the femur, and the highest stress values on the surface of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage in each model were recorded. The six highest points were used to calculate the mean value.

RESULTS

The highest stress values on the surface of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage increased with an increase in the femoral prosthesis varus/valgus angle. As compared with the standard position of the femoral prosthesis, there was no significant difference in the surface stress values of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus and tibial lateral plateau cartilage when the femoral prosthesis varus/valgus angle was less than 4° (p > 0.05). In addition, the stress magnitude on the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage significantly increased when the femoral prosthesis varus/valgus angle was greater than 4° (p < 0.001).

CONCLUSIONS

The optimal femoral prosthesis varus/valgus angle in UKA was less than 4°.

Economic evaluation of high tibial osteotomy: Closing wedge is more cost-effective than open wedge technique when analysing the KOOS-12 improvement

PURPOSE

The purpose of this study was to compare the cost-effectiveness of two techniques for performing a knee valgus osteotomy: opening wedge high tibial osteotomy (OW-HTO) vs closing wedge high tibial osteotomy (CW-HTO).

METHODS

In this economic evaluation study, a cost-effectiveness analysis from the perspective of the Spanish public healthcare system was performed, comparing OW-HTO with CW-HTO. All patients with medial knee osteoarthritis who underwent one of these procedures between 2018 and 2020 in our institution were included. The cost analysis included operating room, implant, graft and hospital admission costs. Functional outcomes (KOOS-12, Tegner activity scale, pain and satisfaction) and radiological outcomes (hip-knee-ankle angle, medial proximal tibial angle, tibial slope and patellar height) were analysed. The cost-effectiveness ratio was obtained by calculating the cost of improving the minimal clinically important difference (MCID) of KOOS-12 for each procedure. All costs are expressed in 2020 euros.

RESULTS

Fifty-one patients met the inclusion criteria (27 OW-HTO and 24 CW-HTO). Good to excellent functional outcomes, significant pain reduction (>6 points) and high patient satisfaction (>9/10) were observed in both groups. Both techniques yielded excellent radiological outcomes. N.s. differences in functional or radiological outcomes improvements between both procedures were found. However, the OW-HTO group presented a higher total cost than the CW-HTO group (4612.1 ± 765.6€ vs. 1827.1 ± 701.9€; p < 0.001). The cost-effectiveness ratio was 818.1 ± 46.8 €/MCID for the CW-HTO procedure and 2414.3 ± 115.2 €/MCID for the OW-HTO procedure (p = 0.025).

CONCLUSION

The CW-HTO procedure presented a cost-effectiveness ratio almost three times lower than the OW-HTO procedure. Both techniques allowed to achieve of good to excellent functional outcomes, significant pain reduction and high patient satisfaction while correcting the varus limb malalignment and the metaphyseal tibial varus in patients with medial compartment osteoarthritis.

LEVEL OF EVIDENCE

Level III; economic study.

Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis

BACKGROUND

Previous research has focused on the perioperative or short-term (<1 year) mortality rate of total knee arthroplasty (TKA), leaving the long-term (>1 year) mortality rate unresolved. In this study, we calculated the mortality rate up to 15 years after primary TKA.

METHODS

Data from the New Zealand Joint Registry from April 1998 to December 2021 were analyzed. Patients aged 45 years or older who underwent TKA for osteoarthritis were included. Mortality data were linked with national records from births, deaths, and marriages. To determine the expected mortality rates in the general population, age-sex-specific life tables from statistics New Zealand were used. Mortality rate was presented as standardized mortality ratios (SMRs) - a comparison of relative mortality rate between the TKA and general populations. In total, 98,156 patients with a median follow-up of 7.25 years (range, 0.00 to 23.74) were included.

RESULTS

Over the entire follow-up period, 22,938 patients (23.4%) had died. The overall SMR for the TKA cohort was 1.08 (95% confidence interval (CI): 1.06 to 1.09), suggesting that TKA patients have an 8% higher mortality rate compared to the general population. However, a reduction in short-term mortality rate was observed for TKA patients up to 5 years post TKA (SMR 5 years post TKA; 0.59 95% CI: 0.57 to 0.60]). On the contrary, a significantly increased long-term mortality rate was observed in TKA patients with greater than 11 years of follow-up, particularly in men over the age of 75 years (SMR 11 to 15 years post TKA for males ≥ 75 years; 3.13 [95% CI: 2.95 to 3.31]).

CONCLUSION

The results suggest a reduction in short-term mortality rate for patients who undergo primary TKA. However, there is an increased long-term mortality rate particularly in men over the age of 75 years. Importantly, the mortality rates observed in this study cannot be causally attributed to TKA alone.

Prediction of early functional outcomes in patients after robotic-assisted total knee arthroplasty: a nomogram prediction model

BACKGROUND

Robotic-assisted total knee arthroplasty (RA-TKA) is becoming more and more popular as a treatment option for advanced knee diseases due to its potential to reduce operator-induced errors. However, the development of accurate prediction models for postoperative outcomes is challenging. This study aimed to develop a nomogram model to predict the likelihood of achieving a beneficial functional outcome. The beneficial outcome is defined as a postoperative improvement of the functional Knee Society Score (fKSS) of more than 10 points, 3 months after RA-TKA by early collection and analysis of possible predictors.

METHODS

This is a retrospective study on 171 patients who underwent unilateral RA-TKA at our hospital. The collected data included demographic information, preoperative imaging data, surgical data, and preoperative and postoperative scale scores. Participants were randomly divided into a training set ( N =120) and a test set ( N =51). Univariate and multivariate logistic regression analyses were employed to screen for relevant factors. Variance inflation factor was used to investigate for variable collinearity. The accuracy and stability of the models were evaluated using calibration curves with the Hosmer-Lemeshow goodness-of-fit test, consistency index and receiver operating characteristic curves.

RESULTS

Predictors of the nomogram included preoperative hip-knee-ankle angle deviation, preoperative 10-cm Visual Analogue Scale score, preoperative fKSS score and preoperative range of motion. Collinearity analysis with demonstrated no collinearity among the variables. The consistency index values for the training and test sets were 0.908 and 0.902, respectively. Finally, the area under the receiver operating characteristic curve was 0.908 (95% CI 0.846-0.971) in the training set and 0.902 (95% CI 0.806-0.998) in the test set.

CONCLUSION

A nomogram model was designed hereby aiming to predict the functional outcome 3 months after RA-TKA in patients. Rigorous validation showed that the model is robust and reliable. The identified key predictors include preoperative hip-knee-ankle angle deviation, preoperative visual analogue scale score, preoperative fKSS score, and preoperative range of motion. These findings have major implications for improving therapeutic interventions and informing clinical decision-making in patients undergoing RA-TKA.

Economic evaluation of acupuncture as an adjunctive treatment with usual care for mild-to-moderate knee osteoarthritis: A Markov model-based analysis

Background

Collaborative care (CC), in which acupuncture is combined with usual care (UC), improves clinical outcomes and increases costs in knee osteoarthritis (KOA). We evaluated the economic feasibility of CC for Korean female patients with mild-to-moderate KOA by using a cost-effectiveness approach.

Methods

Two alternatives for KOA (1. UC as a comparator; and 2. CC as an intervention) were defined based on clinical guidelines, official Korean statistics, and expert validation. Each alternative was simulated in a Markov model every 6 months for 10 years. Estimates of costs, utilities, and transition probabilities were obtained from official statistics and previous studies. The effectiveness of CC was synthesized from randomized controlled trials. A base-case analysis of a limited societal perspective, univariate sensitivity analysis, and probability sensitivity analysis were performed. An annual discount rate of 4.5% and threshold of 20,000 United States dollar per Quality-adjusted life year (USD/QALY) were applied.

Results

Every incremental cost-effectiveness ratio (ICER) of CC calculated from the analyses was sub-threshold. In the base-case analysis, with a limited societal perspective, the ICER was 11,085 USD/QALY. The ICERs from the univariate sensitivity analyses were -2,577-16,748 USD/QALY. The average ICER in the probability sensitivity analysis was 12,412 USD/QALY. When the threshold surpassed 8,000 USD/QALY, the cost-effectiveness of CC exceeded 50%. The probability was 70.27% when the threshold was 20,000 USD/QALY.

Conclusions

CC for Korean female patients with mild-to-moderate KOA was generally cost-effective. Considering the limitations of the evidence, we propose a re-evaluation using further clinical studies in the future.

Unicompartmental Knee Arthroplasty Provides Superior Clinical and Radiological Outcomes Compared to High Tibial Osteotomy at a Follow-Up of 5-8 Years

BACKGROUND

Knee Osteoarthritis (OA) is a debilitating disease. Initially, the medial compartments are affected in most cases. For this pathology, joint preservation is preferable. Two surgical procedures aim to meet this goal: high-tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA). The aim was to compare clinical and radiological outcomes of HTO versus UKA in patients with unicompartmental, medial OA.

METHOD

Retrospective case series. A total of 86 (61 UKA, 25 HTO) patients that received either treatment at a single, specialized center were assessed pre-operatively and at a single follow-up examination at 77.13 months (±8.170). The Knee Society Score (KSS), range of motion (ROM), SF36 questionnaire and the Tegner score were used. The Kellgren-Lawrence score was assessed pre- and post-surgically. Survivorship with the endpoint "revision" was assessed.

RESULTS

The UKA group showed significantly better improvements in KSS scores for pain (p < 0.006) and function (p < 0.001). OA progression (p < 0.02) and survivorship (p < 0.018) differed, significantly favoring UKA. ROM, SF36 and Tegner score did not differ significantly.

CONCLUSIONS

The presented mid-to long-term data suggest that UKA provides superior results in selected outcomes. Nevertheless, significant differences in the demographics of treatments indicate the challenge of comparing these two treatments.

Long-Term Survival and Predictors of Failure of Opening Wedge High Tibial Osteotomy

OBJECTIVE

High tibial valgus osteotomy (HTO) is a widely accepted procedure indicated for varus knee with symptomatic osteoarthritis of the medial compartment. However, there is a lack of studies evaluating long term results of this procedure. The primary aim of this study was to evaluate the long-term survival of opening wedge high tibial osteotomy (HTO) for isolated osteoarthritis in the medial compartment of the knee. The secondary objective was to identify independent predictors of conversion to total knee arthroplasty (TKA).

METHODS

This is a long term retrospective study of 296 cases of open wedge HTOs performed at a single center (level of evidence IV) between January 2005 and August 2015. Opening wedge medial HTO was always performed after diagnostic arthroscopy. Eighty-three percent of the population (233 patients, 247 procedures) was followed up at a mean 11.6 years (6-17) by telephone interview, to evaluate the possible conversion to TKA. Mean age at the index operation was 42.8 years (range 15-70) and most patients were male (70%). Associated procedures (e.g., platelet rich plasma supplementation, microfractures, meniscectomy, etc.) were carried out at the time of the HTO in 80 (32%) cases. Survival of HTO and its association with age, sex, body mass index, smoking habit, preoperative severity of varus deformity, cartilage status at surgery, and associated procedures were evaluated. Kaplan-Meier and Cox regression analyses were performed.

RESULTS

Thirty-three of the 247 HTOs (13.4%) were converted to knee replacement, with 86.6% of the original procedures surviving at a mean 12-year follow-up. Kaplan-Meier survival estimates at 17 years for HTO were 75.5% (95% confidence interval [CI] 66.7-84.3). There was significant difference (P < 0.001) in the 17-year survival rate between obese (55.5%; 95% CI 35.3-75.6) and non-obese (79.7%; 95% CI 70.1-89.2) patients. The determinants of conversion to knee arthroplasty detected at multivariate Cox regression analysis were body mass index, severity of cartilage degeneration in the medial compartment (Outerbridge grade), and age.

CONCLUSION

The long-term survival of open wedge HTO for osteoarthritis in the medial compartment of the knee is satisfactory. The risk of conversion to TKA is significantly increased in obese patients. Advanced age and severity of pre-existing cartilage damage may also contribute to the risk of conversion to TKA.

Clinical outcomes of hybrid closed wedge high tibial osteotomy for advanced osteoarthritis of the knee compared with total knee arthroplasty

PURPOSE

To evaluate clinical outcomes between hybrid closed wedge high tibial osteotomy (HCWHTO) and total knee arthroplasty (TKA) for advanced medial compartmental osteoarthritis of the knee (advanced knee OA).

METHODS

In more than grade 3 OA based on the Kellgren-Lawrence classification, when patients' age was less than 60 years or activity level was more than level 5 based on the UCLA activity score, 22 knees (18 patients) underwent HCWHTO. The other 22 knees (18 patients) that underwent TKA were evaluated retrospectively. Muscle strength was evaluated preoperatively and at 1 year postoperatively. The visual analogue scale (VAS) and Japanese version of the Knee injury and Osteoarthritis Outcome Score (J-KOOS) were used to evaluate clinical outcomes preoperatively and at a mean 66-months follow-up.

RESULTS

All postoperative muscle strength measures improved to preoperative equivalent levels in the HCWHTO group; they were significantly higher in the HCWHTO group than in the TKA group (p < .05). The VAS score and total J-KOOS significantly improved in both groups (HCWHTO, p = .001; TKA, p = .040); there were no significant differences in the scores between the groups at the final follow-up. Hybrid closed wedge HTO significantly improved the activities of daily living and sport/recreation scores, whereas TKA did not at the final follow-up.

CONCLUSIONS

In advanced knee OA, HCWHTO led to improved muscle strength, and its midterm clinical outcomes were equivalent to those of TKA. To postpone or even to avoid TKA, HCWHTO is considered an appropriate treatment for young and high-activity patients with advanced knee OA.

LEVEL OF EVIDENCE

Therapeutic Level III.

Unicompartmental knee arthroplasty is associated with lower pain levels but inferior range of motion, compared with high tibial osteotomy: a systematic overview of meta-analyses

Background

The purpose of this study was to overview the findings of reported meta-analyses on unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO).

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 (PRISMA 2020) guidelines were followed. Two independent reviewers conducted a literature search of PubMed, Embase, the Web of Science, and the Cochrane Database of Systematic Reviews for meta-analyses comparing UKA and HTO that were published prior to September 2021. Literature screening, data extraction, and article quality appraisal were performed according to the study protocol registered online at PROSPERO (CRD42021279152).

Results

A total of 10 meta-analyses were identified, and different studies reported different results. Five of the seven meta-analyses showed that the proportion of subjects with excellent or good functional results was higher for UKA than for HTO. All three meta-analyses showed that UKA was associated with lower pain levels, and all six of the studies that included an analysis of range of motion (ROM) reported that UKA was inferior to HTO. Four of the eight meta-analyses found that total complication rates were lower for UKA. Only 3 of the 10 meta-analyses found that UKA had lower revision rates. Moreover, in the subgroup analysis, the revision and complication rates of UKA were similar to those of opening-wedge HTO but much lower than those of closing-wedge HTO.

Conclusions

Compared to HTO, UKA was associated with lower pain levels but inferior postoperative ROM. The results were inconclusive regarding whether UKA yielded better knee function scores and lower revision or complication rates than HTO. Accurate identification of indications and appropriate patient selection are essential for treating individuals with OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03319-7.

Fixed-bearing unicompartmental knee arthroplasty provides a lower failure rate than mobile-bearing unicompartimental knee arthroplasty when used after a failed high tibial osteotomy: a systematic review and meta-analysis

Despite the fact that the choice of bearing design has been thought to influence the functional outcomes and longevity of unicompartimental knee arthroplasty (UKA), there is a lack of clinical evidence supporting the decision-making process in patients who have undergone high tibial osteotomy (HTO). A systematic review of studies was carried out that reported the outcomes of fixed-bearing (FB) or mobile-bearing (MB) medial UKA in patients with a previous HTO. A random effect meta-analysis using a generalized linear mixed-effects model to calculate revision rates was done. Seven retrospective cohort studies were included for this study. Regarding the fixation method, 40 were the FB-UKA and 47 were MB-UKA. For both groups, the mean post-operative follow-up was 5.8 years. The survival rates were 92% for the FB-UKA with a mean follow-up of 10 years. For the MB-UKA, it ranged from 35.7 to 93%, with a mean follow-up of 4.2 years. For the FB, the time to revision was reported as 9.3 years, while 1.2, 2.5 and 2.91 years was reported for the MB. The results of the meta-analysis showed that the revision rate for the patients receiving a FB-UKA after failed HTO was 8%, compared to 17% in those who received an MB-UKA. The results of the review suggest that the use of the FB-UKA is associated with lower revision rates and a longer survival time than the MB-UKA and have similar functional ability scores.Level of evidence: III (systematic review of level-III studies).

Unicompartmental knee arthroplasty is superior to high tibial osteotomy for the treatment of medial unicompartmental osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) are widely used for the treatment of medial unicompartmental knee osteoarthritis (OA). However, the best approach remains controversial. This study aimed to present a systematic review and a meta-analysis to directly compare the clinical outcomes between HTO and UKA. We hypothesized that the clinical outcomes after UKA and HTO would be similar.

METHODS

Electronic databases (Web of Science, PubMed, Embase, CENTRAL, and Biosis Preview) were searched for related studies published before November 30, 2021. Retrospective and prospective studies that directly compared the postoperative outcomes between UKA and HTO were included. Odds ratio (ORs) and 95% confidence interval (CIs) for complications, revision to total knee arthroplasty (TKA), and weighted mean difference (MD) and 95% CIs in range of motion (ROM), pain, walking speed and function score were evaluated. Two reviewers independently assessed the quality of the studies. Subgroup and sensitivity analyses were performed to explore the heterogeneity.

RESULTS

Twenty-three retrospective and 6 prospective studies were included. A total of 3004 patients (3084 knees) were evaluated for comparison. Complications (OR, 4.88, 95% CI: 2.92-6.86) were significantly greater in the HTO group than in the UKA group. Postoperative function scores including Lysholm score (MD, -2.78, 95% CI: -5.37 to -0.18) and Hospital for Special Surgery (HSS) score (MD, -2.80, 95% CI: -5.39 to -0.20) were significantly lower in the HTO group than the UKA group. The postoperative ROM was similar between HTO and mobile-bearing UKA (MD, -3.78, 95% CI: -15.78 to 8.22). However, no significant differences were observed between the HTO and UKA group in terms of postoperative pain, walking speed, and revision to TKA.

CONCLUSIONS

UKA is superior to HTO in minimizing complications and enhancing postoperative function scores. Mobile-bearing UKA has a similar ROM compared with HTO. Both HTO and UKA provide satisfactory clinical outcomes in terms of walking speed, relieving pain, and revision to TKA. UKA appears to be more suitable for the elderly, and both mobile-bearing UKA and HTO are viable surgical options for younger active individuals.

Understanding Health Economics in Joint Replacement Surgery

The number of arthroplasty procedures has been rising at a significant rate, contributing to a notable portion of the nation's health care spending. This growth has contributed to an increase in the number of health care economic studies in the field of adult reconstruction surgery. Although these articles are filled with important information, they can be difficult to understand without a background in business or economics. The goal of this review is to define the common terminology used in health care economic studies, assess their value and benefit in the context of total joint arthroplasty, and highlight shortcomings in the current literature. [Orthopedics. 2022;45(4):e174-e182.].

High Tibial Osteotomy Versus Unicompartmental Knee Arthroplasty for Unicompartmental Knee Osteoarthritis: A Systematic Review and Meta-Analysis

Purpose

High tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are commonly performed procedures for the treatment of compartmental knee osteoarthritis; however, the optimal procedure remains controversial. We conducted this systematic review and meta-analysis to compare the functional outcomes and assess complications and revision rates between the two techniques.

Methods

We searched electronic databases for relevant studies comparing HTO versus UKA for unicompartmental knee osteoarthritis. Continuous data as visual analogue scale (VAS), range of motion, and free walking speed were pooled as mean differences (MDs). Dichotomous data as functional knee outcomes, complications, and revision were pooled as odds ratios (ORs), with 95% confidence interval (CI), using R software for windows.

Results

Twenty-five studies involving 8185 patients were included. Meta-analysis showed that HTO was associated with higher risk of complications (OR = 2.47, 95% CI [1.52, 4.04]), poorer functional results (excellent/good) (OR = 0.32, 95% CI [0.21, 0.49]), and greater range of motion (MD = 7.05, 95% CI [2.41, 11.68]) compared to UKA. No significant differences were found between the compared groups in terms of VAS (MD = 0.14, 95% CI [- 0.08, 0.36]), revision rates (OR = 1.30, 95% CI [0.65, 2.60]), and free walking speed (MD = - 0.05, 95% CI [- 0.11, 0.00]).

Conclusion

This study showed that UKA achieved fewer complications, better functional outcomes, and less range of motion compared to HTO. No significant differences were detected between HTO and UKA in terms of VAS and revision rate. Treatment options should be personalized to each patient considering factors such as their age, activities of daily living, their body mass index, and severity of osteoarthritis.

Level of evidence

II.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-022-00620-9.

Editorial Commentary: Avoid Creating an Oblique Joint Line After an Opening Medial Wedge High Tibial Osteotomy

A medial opening wedge high tibial osteotomy is a cost-effective procedure for younger patients with symptomatic medial compartment knee arthritis. A high rate of success can be expected, but excessive postoperative joint line obliquity is associated with inferior clinical outcomes. If preoperative planning predicts that the postoperative medial proximal tibial angle, the medial angle between the tibial anatomical axis and the joint line of the proximal tibia, will exceed 95°, a surgeon should consider performing a double-level osteotomy (combined proximal tibial and distal femoral osteotomies).

St Georg Sled medial unicompartmental arthroplasty: survivorship analysis and function at 20 years follow up

PURPOSE

The peri-operative and short-term benefits of unicompartmental knee arthroplasty (UKA) are well supported in the literature. However, there remains concern regarding the higher revision rate when compared with total knee replacement. This manuscript reports the functional outcome and survivorship of a large series of fixed bearing, medial unicompartmental replacements (St Georg Sled), with a minimum of 20 years follow-up.

METHODS

Between 1974 and 1994, 399 patients (496 knees) underwent a medial fixed-bearing UKA. Prospective data were collected pre-operatively and at regular intervals post-operatively using the Bristol Knee Score (BKS), Oxford Knee (OKS) and Western Ontario MacMaster (WOMAC) scores. Kaplan-Meier survival analysis was used to determine survivorship, with revision or need for revision as end point, and differences assessed using Mantel-Cox log rank test.

RESULTS

Functional knee scores improved post-operatively, but demonstrated a slight decline from 10 years of follow-up onwards. Survivorship is estimated as 86% at 10 years, 80% at 15 years, and 78% at 20 years. Sixty knees were revised, with progression of disease in another compartment the commonest reason. Eighty eight percent were revised using a primary prosthesis. For patients over the age of 65 years at the time of index procedure, 93% died with a functioning prosthesis in situ.

CONCLUSION

Medial UKA demonstrates good long-term function and survivorship, and represents an excellent surgical option for patients aged over 65 years of age, where few patients will require a revision procedure.

LEVEL OF EVIDENCE

IV.

A comparative study of 21,194 UKAs and 49,270 HTOs for the risk of unanticipated events in mid-age patients from the national claims data in South Korea

Background

Both high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are well-established treatments for medial knee osteoarthritis (OA). However, over the past 20 years, results of comparisons of long-term survival rates and outcomes have remained controversial. Furthermore, in patients at the boundary age, from 50 to 70 years, considering age as a treatment indication, selecting a surgical method is difficult. Therefore, we aimed to investigate conversion rates to total knee arthroplasty (TKA) and perioperative adverse outcomes between the two surgical methods in mid-age patients.

Methods

We extracted data from the Korean National Health Insurance claims database. A total of 70,464 patients aged between 50 and 70 years, considered as mid-age patients were included in the final study population. We used a multivariable Cox proportional hazard regression model, adjusting for potential confounders such as age, sex, insurance type, region of residence, hospital type, comorbidities, and the Charlson comorbidity Index (CCI).

Results

Of the 70,464 patients, 21,194 were treated with UKA and 49,270 were treated with HTO. HTO showed a higher risk of revision than UKA at five, and 10 years and during the whole observation period. The incidence of deep vein thromboembolism, and surgical site infection was significantly higher in UKA than in HTO.

Conclusions

It is important to choose an appropriate surgical method considering that UKA has better results in terms of long-term survival rates but may have a higher incidence of various complications.

High usage of medial unicompartmental knee arthroplasty negatively influences total knee arthroplasty revision rate

PURPOSE

Surgeons with higher medial unicompartmental knee arthroplasty (UKA) usage have lower UKA revision rates. However, an increase in UKA usage may cause a decrease of total knee arthroplasty (TKA) usage. The purpose of this study was to investigate the influence of UKA usage on revision rates and patient-reported outcomes (PROMs) of UKA, TKA, and combined UKA + TKA results.

METHODS

Using the New Zealand Registry Database, surgeons were divided into six groups based on their medial UKA usage: < 1%, 1-5%, 5-10%, 10-20%, 20-30% and > 30%. A comparison of UKA, TKA and UKA + TKA revision rates and PROMs using the Oxford Knee Score (OKS) was performed.

RESULTS

A total of 91,895 knee arthroplasties were identified, of which 8,271 were UKA (9.0%). Surgeons with higher UKA usage had lower UKA revision rates, but higher TKA revision rates. The lowest TKA and combined UKA + TKA revision rates were observed for surgeons performing 1-5% UKA, compared to the highest TKA and UKA + TKA revision rates which were seen for surgeons using > 30% UKA (p < 0.001 TKA; p < 0.001 UKA + TKA). No clinically important differences in UKA + TKA OKS scores were seen between UKA usage groups at 6 months, 5 years, or 10 years.

CONCLUSION

Surgeons with higher medial UKA usage have lower UKA revision rates; however, this comes at the cost of a higher combined UKA + TKA revision rate that is proportionate to the UKA usage. There was no difference in TKA + UKA OKS scores between UKA usage groups. A small increase in TKA revision rate was observed for high-volume UKA users (> 30%), when compared to other UKA usage clusters. A significant decrease in UKA revision rate observed in high-volume UKA surgeons offsets the slight increase in TKA revision rate, suggesting that UKA should be performed by specialist UKA surgeons.

LEVEL OF EVIDENCE

III, Retrospective therapeutic study.

Role of high tibial osteotomy in medial compartment osteoarthritis of the knee: Indications, surgical technique and outcomes

Knee osteoarthritis (OA) is the most common joint disorder worldwide. In particular, primary knee OA often presents with a varus malalignment. This increases the loads going through the medial compartment resulting in cartilage degeneration and symptomatic arthritis. High tibial osteotomy (HTO) is the workhorse surgical procedure for treating medial knee OA. When performed precisely in the hands of an experienced surgeon, HTO can delay or avoid knee arthroplasty. Of note, outcomes of knee arthroplasty are at best unpredictable in patients of younger age. Hence, there is a growing need for joint preservation procedures for younger patients presenting with knee OA, of which HTO is one. Through this article, the authors of whom all are joint preservation surgeons with a special interest in osteotomy hope to share from their experience as well as the available literature on the indications, perioperative planning, surgical technique, outcomes as well as pearls and pitfalls of HTO.

Risk of Revision and Adverse Outcomes Following Partial Knee Replacement and High Tibial Osteotomy for Unicompartmental Knee Osteoarthritis: A Nationwide Cohort Study

PURPOSE

To investigate comparative study for potential associations of adverse outcomes as well as survival rates after high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA).

METHODS

We reviewed the Korean National Health Insurance claims database from January 1, 2007 to May 31, 2019. A total of 90,705 patients aged 30-90 years who were newly treated for HTO or UKA were identified considering their eligibility. We performed four rounds of propensity score matching to reduce imbalance of baseline characteristics, especially disparities among different age groups. Multivariable logistic regression models were used to compare the risk of revision and various unwanted medical problems between HTO and UKA treatment groups after propensity score matching.

RESULTS

23,563 matched patients were assigned to each group on the basis of propensity score. HTO showed higher risk of revision than UKA at 5 years, 10 years and the whole observed period (hazard ratio: 1.21, 95% CI 1.10-1.34). Deep vein thromboembolism (0.27, 0.21-0.35), and surgical site infection (0.37, 0.30-0.44) were less likely for HTOs than UKAs. Postoperative admission to intensive care unit was significantly lower with HTO (odds ratio: 0.40, 0.29-0.54) while rehospitalization within 30 days (1.27, 1.16-1.38) and 90 days (1.24, 1.18-1.30) were higher than UKA.

CONCLUSION

When choosing the surgical method for unicompartmental knee OA, not only the survival rate, but also the risk of other adverse outcomes should be considered. In particular, attention should be paid to the risk of developing deep vein thromboembolism and surgical site infection.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-021-00517-z.

Salvage of severe knee osteoarthritis: efficacy of tibial condylar valgus osteotomy versus open wedge high tibial osteotomy

INTRODUCTION

To compare the clinical outcomes and the radiographic features between tibial condylar valgus osteotomy (TCVO) and open wedge high tibial osteotomy (OWHTO). New insight into the indication criteria for TCVO was also clarified for achieving satisfactory results.

MATERIALS AND METHODS

Sixty-three knees with medial-compartment osteoarthritis were retrospectively studied. Thirty-four knees with subluxated lateral joint and depression of the medial tibial plateau underwent TCVO and the rest underwent OWHTO. Among the 63 knees included, 27 knees with a pre-operative femorotibial angle (FTA) ≥ 185° were defined as severe varus (subgroup S, 15 in S_TCVO group and 12 in S_HTO group). Lower limb alignment, intra-, and extra-articular congruency were evaluated according to the radiograph obtained before and 24 months after surgery. The visual analog scale (VAS) score and Hospital for Special Surgery (HSS) score were obtained to assess the clinical results. Opening angle and distance of the opening gap in each group were measured by intra-operative fluoroscopy.

RESULTS

During the 2-year follow-up period, the mean HSS score increased from 70.3 to 81.4 in HTO group and 65.9 to 87.3 in TCVO group (p < 0.05). The mean VAS score decreased from 5.9 to 2.6 and 6.0 to 2.1, respectively (p < 0.01). Pre-operative FTA was restored to 172.9° in HTO group and 171.3° in TCVO group, and percentage of mechanical axis (%MA) was improved to 59.7% and 61.2%, respectively. Joint line convergence angle (JLCA) was slightly restored and medial tibial plateau depression (MTPD) was relatively the same before and after OWHTO, while these parameters improved greatly (from 6.4° to 1.2° and - 8.0° to 5.9°, p < 0.01) in TCVO group. More undercorrected knees were observed in S_HTO group than S_TCVO group (58.3% and 13.3%, p < 0.05). Opening angle and distance of the opening gap were larger in TCVO group (19.1° and 14.0 mm) than those in OWHTO group (9.3° and 10.1 mm, p < 0.05).

CONCLUSION

Compared to OWHTO, TCVO had priority in treating advanced knee OA with intra-articular deformity. However, TCVO had a limited capacity to correct the varus angle. Besides, TCVO might be suitable for medial-compartment OA with a pre-operative FTA ≥ 185°.

Health Economic Evaluations of Hip and Knee Interventions in Orthopaedic Sports Medicine: A Systematic Review and Quality Assessment

BACKGROUND

The economic burden of musculoskeletal diseases is substantial and growing. Economic evaluations compare costs and health benefits of interventions simultaneously to help inform value-based care; thus, it is crucial to ensure that studies are using appropriate methodology to provide valid evidence on the cost-effectiveness of interventions. This is particularly the case in orthopaedic sports medicine, where several interventions of varying costs are available to treat common hip and knee conditions.

PURPOSE

To summarize and evaluate the quality of economic evaluations in orthopaedic sports medicine for knee and hip interventions and identify areas for quality improvement.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

The Medline, AMED, OVID Health Star, and EMBASE databases were searched from inception to March 1, 2020, to identify economic evaluations that compared ≥2 interventions for hip and/or knee conditions in orthopaedic sports medicine. We assessed the quality of full economic evaluations using the Quality of Health Economic Studies (QHES) tool, which consists of 16 questions for a total score of 100. We classified studies into quartiles based on QHES score (extremely poor quality to high quality) and we evaluated the frequency of studies that addressed each of the 16 QHES questions.

RESULTS

A total of 93 studies were included in the systematic review. There were 41 (44%) cost analyses, of which 21 (51%) inappropriately concluded interventions were cost-effective. Only 52 (56%) of the included studies were full economic evaluations, although 40 of these (77%) fell in the high-quality quartile. The mean QHES score was 83.2 ± 19. Authors consistently addressed 12 of the QHES questions; questions that were missed or unclear were related to statistical uncertainty, appropriateness of costing methodology, and discussion of potential biases. The most frequently missed question was whether the cost perspective of the analysis was stated and justified.

CONCLUSION

The number of studies in orthopaedic sports medicine is small, despite their overall good quality. Yet, there are still many highly cited studies based on low-quality or partial economic evaluations that are being used to influence clinical decision-making. Investigators should follow international health economic guidelines for study design and critical appraisal of studies to further improve quality.

Progress in the treatment of knee osteoarthritis with high tibial osteotomy: a systematic review

BACKGROUND

High tibial osteotomy (HTO) has been used for over 60 years in clinical practice and mainly comprises two major techniques: closed wedge high tibial osteotomy (CWHTO) and open wedge high tibial osteotomy (OWHTO). However, these have been gradually replaced by total knee arthroplasty (TKA), due to inconsistent clinical results and many complications. With the concept of knee-protection and ladder treatment of osteoarthritis, as an effective minimally invasive treatment for knee osteoarthritis, HTO has once again received attention.

METHODS

A systematic literature search was conducted in PubMed, Embase, ClinicalKey, CNKI, and the China Wanfang database. The search terms relating to osteoarthritis and high tibial osteotomy were used. Studies were considered eligible if the participants were adults with knee osteoarthritis (KOA) who had undergone HTO. A total of two reviewers participated in the selection of the studies. Reviewer 1 was assigned to screen titles and abstracts, and reviewer 2 to screen full-text data. Data extraction was completed by reviewer 2, and 30% were checked by the research team. Potential conflicts were resolved through discussion. The methodological quality was assessed using a risk of bias, based on the Cochrane handbook and Newcastle-Ottawa assessment scale. The outcome indicators are (1) posterior slope of tibial plateau, (2) the height of the patella, (3) fracture in the osteotomy plane, (4) survival rate, (5) special surgery knee score (HSS), and (6) the recurrence of varus deformity of the included studies were evaluated according to the guidelines of the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) working group (Atkins et al., BMJ 328:1490, 2004).

RESULTS

Among the 18 articles included, 10 were prospective cohort studies, five were randomized controlled trial (RCT) studies, one was prospective comparative study (PCS), one was retrospective comparative study (RCS), and one was retrospective cohort. The earliest publication year was 1999, and the most recent was 2018. A total of 6555 eligible cases were included, comprised of 3351 OWHTO patients and 3204 CWHTO patients. Five RCT were assessed using risk of bias, based on the Cochrane handbook. Eleven cohort studies and two case-control studies were assessed using the Newcastle-Ottawa assessment scale. These six outcome indicators for a total of twenty-four evidence individuals were evaluated separately, among which the GRADE classification of 1, 2, and 6 was medium quality, and 3, 4, and 5 were low quality. Based on our systematic review, regardless of whether the chosen procedure was OWHTO or CWHTO, both HSS scores increased significantly as compared with the preoperative scores. Compared with CWHTO, the height of the patella and tibial posterior slope angle increased following OWHTO. Additionally, OWHTO has a better long-term survival rate and lower fracture rate, supporting OWHTO as the first treatment choice.

CONCLUSIONS

For young patients with knee osteoarthritis (KOA), high tibial osteotomy (HTO) can be considered as a treatment option to replace total knee arthroplasty (TKA) to reduce the economic burden and promote the reasonable allocation of medical resources. This study shows that compared with CWHTO, OWHTO has certain advantages in long-term survival rate and lower fracture rate, but the level of evidence is lower. In the future, we will need larger sample sizes and longer follow-up randomized controlled trials to improve our research.

Total knee replacement after high tibial osteotomy: time-to-event analysis and predictors

BACKGROUND

An important aim of high tibial osteotomy (HTO) is to prevent or delay the need for total knee replacement (TKR). We sought to estimate the frequency and timing of conversion from HTO to TKR and the factors associated with it.

METHODS

We prospectively evaluated patients with osteoarthritis (OA) of the knee who underwent medial opening wedge HTO from 2002 to 2014 and analyzed the cumulative incidence of TKR in July 2019. The presence or absence of TKR on the HTO limb was identified from the orthopedic surgery reports and knee radiographs contained in the electronic medical records for each patient at London Health Sciences Centre. We used cumulative incidence curves to evaluate the primary outcome of time to TKR. We used multivariable Cox proportional hazards analysis to assess potential preoperative predictors including radiographic disease severity, malalignment, correction size, pain, sex, age, body mass index (BMI) and year of surgery.

RESULTS

Among 556 patients who underwent 643 HTO procedures, the cumulative incidence of TKR was 5% (95% confidence interval [CI] 3%-7%) at 5 years and 21% (95% CI 17%-26%) at 10 years. With the Cox proportional hazards multivariable model, the following preoperative factors were significantly associated with an increased rate of conversion: radiographic OA severity (adjusted hazard ratio [HR] 1.96, 95% CI 1.12-3.45), pain (adjusted HR 0.85, 95% CI 0.75-0.96)], female sex (adjusted HR 1.67, 95% CI 1.08-2.58), age (adjusted HR 1.50 per 10 yr, 95% CI 1.17-1.93) and BMI (adjusted HR 1.31 per 5 kng/m2, 95% CI 1.12-1.53).

INTERPRETATION

We found that 79% of knees did not undergo TKR within 10 years after undergoing medial opening wedge HTO. The strongest predictor of conversion to TKR is greater radiographic disease at the time of HTO.

Choice between implants in knee replacement: protocol for a Bayesian network meta-analysis, analysis of joint registries and economic decision model to determine the effectiveness and cost-effectiveness of knee implants for NHS patients-The KNee Implant Prostheses Study (KNIPS)

INTRODUCTION

Knee replacements are highly successful for many people, but if a knee replacement fails, revision surgery is generally required. Surgeons and patients may choose from a range of implant components and combinations that make up knee replacement constructs, all with potential implications for how long a knee replacement will last. To inform surgeon and patient decisions, a comprehensive synthesis of data from randomised controlled trials is needed to evaluate the effects of different knee replacement implants on overall construct survival. Due to limited follow-up in trials, joint registry analyses are also needed to assess the long-term survival of constructs. Finally, economic modelling can identify cost-effective knee replacement constructs for different patient groups.

METHODS AND ANALYSIS

In this protocol, we describe systematic reviews and network meta-analyses to synthesise evidence on the effectiveness of knee replacement constructs used in total and unicompartmental knee replacement and analyses of two national joint registries to assess long-term outcomes. Knee replacement constructs are defined by bearing materials and mobility, constraint, fixation and patella resurfacing. For men and women in different age groups, we will compare the lifetime cost-effectiveness of knee replacement constructs.

ETHICS AND DISSEMINATION

Systematic reviews are secondary analyses of published data with no ethical approval required. We will design a common joint registry analysis plan and provide registry representatives with information for submission to research or ethics committees. The project has been assessed by the National Health Service (NHS) REC committee and does not require ethical review.Study findings will be disseminated to clinicians, researchers and administrators through open access articles, presentations and websites. Specific UK-based groups will be informed of results including National Institute for Health Research and National Institute for Health and Care Excellence, as well as international orthopaedic associations and charities. Effective dissemination to patients will be guided by our patient-public involvement group and include written lay summaries and infographics.

PROSPERO REGISTRATION NUMBER

CRD42019134059 and CRD42019138015.

Patient Preferences for Surgical Treatment of Knee Osteoarthritis: A Discrete-Choice Experiment Evaluating Total and Unicompartmental Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a common treatment for end-stage knee osteoarthritis but is associated with increased complication rates compared with unicompartmental knee arthroplasty (UKA). UKA offers better functional outcomes but is associated with a higher risk of revision. The purpose of this study was to apply good-practice, stated-preference methods to quantify patient preferences for benefit-risk tradeoffs associated with arthroplasty treatments for end-stage knee osteoarthritis.

METHODS

A discrete-choice experiment was developed with the following attributes: chance of complications, functional ability, awareness of the knee implant, and chance of needing another operation within 10 years. Patients included those aged 40 to 80 years with knee osteoarthritis. A pivot design filtered respondents into 1 of 2 surveys on the basis of self-reported functional ability (good compared with fair or poor) as measured by the Oxford Knee Score. Treatment-preference data were collected, and relative attribute-importance weights were estimated.

RESULTS

Two hundred and fifty-eight completed survey instruments from 92 males and 164 females were analyzed, with 72 respondents in the good-function cohort and 186 in the fair/poor-function cohort. Patients placed the greatest value or relative importance on serious complications and rates of revision in both cohorts. Preference weights did not vary between cohorts for any attribute. In the good-function cohort, 42% of respondents chose TKA and 58% chose UKA. In the fair/poor-function cohort, 54% chose TKA and 46% chose UKA.

CONCLUSIONS

Patient preferences for various treatment attributes varied among patients in a knee osteoarthritis population. Complication and revision rates were the most important factors to patients, suggesting that physicians should focus on these areas when discussing treatments. The proportion of patients who chose UKA suggests that the current trend of increased UKA utilization is aligned with patient preferences.

CLINICAL RELEVANCE

Systematic elicitation of patient preferences for knee arthroplasty procedures, which lays out evidence-based risks and benefits of different treatments, indicates a larger subset of the knee osteoarthritis population may prefer UKA than would be suggested by the current rates of utilization of the procedure. Arthroplasty treatment should align with patient preferences and eligibility criteria to better deliver patient-centered care.

Medium-term survival and clinical and radiological results in high tibial osteotomy: Factors for failure and comparison with unicompartmental arthroplasty

INTRODUCTION

High tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are two surgical solutions for isolated medial tibiofemoral osteoarthritis. Results depend on preoperative criteria and patient selection, but also on postoperative factors: implant positioning, limb alignment. Factors for HTO survival need identifying to reduce risk of failure requiring total knee arthroplasty (TKA).

HYPOTHESIS

Age, gender, weight, osteoarthritis grade, degree of correction, type of osteotomy, technique and intraoperative complications impact HTO survival.

MATERIAL AND METHOD

As part of a symposium of the French Society of Arthroscopy (SFA), a multicenter retrospective study compared 2 series. The HTO series comprised 488 patients: 153 female (31.4%); mean age, 55.1 years; mean weight, 83.1kg; mean body-mass index (BMI), 28.6. The UKA series comprised 284 patients: 172 female (60.6%); mean age, 64.1 years; mean weight, 75.3kg; mean BMI, 27.6. The main endpoint was comparative survival at 5, 8 and 10 years; secondary endpoints comprised pre- and post-operative hip-knee-ankle (HKA) angle, mechanical femoral angle (mFA) and mechanical tibial angle (mTA), surgical technique, satisfaction, time to and level of return to work, WOMAC and Tegner scores and complications rates. The significance threshold was set at p<0.05; 95% confidence intervals were calculated.

RESULTS

Age>54 years, male gender, BMI>25, medial tibiofemoral wear severity Ahlback ≥3, ≥0.9° varus joint component, HKA correction<8°, postoperative HKA<180° and hinge fracture were significantly associated with poorer survival. There was no impact of type of osteotomy, navigation assistance or postoperative HKA 183-186°. Ten-year survival was 74.3% for HTO and 71% for UKA (non-significant); however, survival curves crossed at 6 years.

CONCLUSION

HTO showed survival and functional results comparable to those of UKA in selected patients when target limb alignment correction was achieved. The present study determined selection criteria. A predictive score for results of either procedure would facilitate decision-making.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

3D-Printed Patient-Specific Instrumentation Technique Vs. Conventional Technique in Medial Open Wedge High Tibial Osteotomy: A Prospective Comparative Study

Purpose

The purpose of this study was to compare the accuracy and clinical outcomes of the medial open wedge high tibial osteotomy (MOWHTO) using a three-dimensional (3D-) printed patient-specific instrumentation (PSI) with that of conventional surgical techniques.

Methods

A prospective comparative study which included 18 patients who underwent MOWHTO using 3D-printed PSI technique (3D-printed group) and 19 patients with conventional technique was conducted from Jan 2019 to Dec 2019. After the preoperative planning, 3D-printed PSI (cutting guide model) was used in MOWHTO for 3D-printed group, while freehand osteotomies were adopted in the conventional group. The accuracy of MOWHTO for each method was compared using the radiological index obtained preoperatively and postoperatively, including mechanical femorotibial angle (mFTA) and medial mechanical proximal tibial angle (mMPTA), and correction error. Regular clinical outcomes were also compared between the 2 groups.

Results

The correction errors in the 3D-printed group were significantly lower than the conventional group (mFTA, 0.2° ± 0.6° vs. 1.2° ± 1.4°, P = 0.004) (mMPTA, 0.1° ± 0.4° vs. 2.2° ± 1.8°, P < 0.00001). There was a significantly shorter duration (P < 0.00001) and lower radiation exposures (P < 0.00001) for the osteotomy procedure in the 3D-printed group than in the conventional group. There were significantly higher subjective IKDC scores (P = 0.009) and Lysholm scores (P = 0.03) in the 3D-printed group at the 3-month follow-up, but not significantly different at other time points. Fewer complications occurred in the 3D-printed group.

Conclusions

With the assistance of the 3D-printed patient-specific cutting guide model, a safe and feasible MOWHTO can be conducted with superior accuracy than the conventional technique.

Unicompartmental knee arthroplasty, an enigma, and the ten enigmas of medial UKA

Unicompartmental knee arthroplasty (UKA) is a bone- and ligament-sparing alternative to total knee arthroplasty in the patients with end-stage single-compartment degeneration of the knee. Despite being a successful procedure, the multiple advantages of UKA do not correlate with its usage, most likely due to the concerns regarding prosthesis survivability, patient selection, ideal bearing design, and judicious use of advanced technology among many others. Therefore, the purpose of this study is to review and summarize the debated literature and discuss the controversies as “Ten Enigmas of UKA.”

Systematic Review of the Evolution of Health-Economic Evaluation Models of Osteoarthritis

OBJECTIVE

To comprehensively synthesize the evolution of health-economic evaluation models (HEEMs) of all osteoarthritis (OA) interventions, including preventions, core treatments, adjunct nonpharmacologic interventions, pharmacologic interventions, and surgical treatments.

METHODS

The literature was searched within health-economic/biomedical databases. Data extracted included OA type, population characteristics, model setting/type/events, study perspective, and comparators; the reporting quality of the studies was also assessed. The review protocol was registered at the International Prospective Register of Systematic Reviews (CRD42018092937).

RESULTS

Eighty-eight studies were included. Pharmacologic and surgical interventions were the focus in 51% and 44% of studies, respectively. Twenty-four studies adopted a societal perspective (with increasing popularity after 2013), but most (63%) did not include indirect costs. Quality-adjusted life years was the most popular outcome measure since 2008. Markov models were used by 62% of studies, with increasing popularity since 2008. Until 2010, most studies used short-to-medium time horizons; subsequently, a lifetime horizon became popular. A total of 86% of studies reported discount rates (predominantly between 3% and 5%). Studies published after 2002 had a better coverage of OA-related adverse events (AEs). Reporting quality significantly improved after 2001.

CONCLUSION

OA HEEMs have evolved and improved substantially over time, with the focus shifting from short-to-medium-term pharmacologic decision-tree models to surgical-focused lifetime Markov models. Indirect costs of OA are frequently not considered, despite using a societal perspective. There was a lack of reporting sensitivity of model outcome to input parameters, including discount rate, OA definition, and population parameters. While the coverage of OA-related AEs has improved over time, it is still not comprehensive.

Should patients aged 75 years or older undergo medial unicompartmental knee arthroplasty? A propensity score-matched study

INTRODUCTION

With increasing life expectancies worldwide, more elderly patients with isolated medial compartment osteoarthritis may become suitable UKA candidates. However, there is a paucity of literature comparing outcomes between older patients (≥ 75 years) and younger patients undergoing UKA. The aim of this study was to determine if there were differences in functional and HRQoL measures between older patients (≥ 75 years) and younger controls (< 75 years) undergoing primary UKA.

MATERIALS AND METHODS

Prospectively collected registry data of 1041 patients who underwent primary, cemented, fixed-bearing medial UKA at a single institution from 2002-2013 were reviewed. Propensity scores generated using logistic regression was used to match older patients (≥ 75 years, n = 94) to controls (< 75 years, n = 188) in a 1:2 ratio. Knee Society Scores, Oxford Knee Score, Short Form-36, satisfaction/expectation scores, proportion of patients attaining OKS/SF-36 PCS MCID and survivorship were analysed.

RESULTS

Patients ≥ 75 years had significantly lower KSFS (67.1 ± 17.9 vs 79.4 ± 18.2, p < 0.001) and SF-36 PCS (47.3 ± 10.1 vs 50.4 ± 9.1, p = 0.01) as compared to the control group. In addition, a significantly lower proportion of patients ≥ 75 years attained MCID for SF-36 PCS when compared to the controls (50.0% vs 63.8%, p = 0.04). Survival rates at mean 8.3 ± 3.0 years were 98.9% (95% CI, 96.7-100) in the older group versus 92.8% (95% CI, 86.8-98.8) in the younger group (p = 0.31).

CONCLUSIONS

Our findings highlight the need to counsel older patients regarding potentially reduced improvements in functional outcomes, despite advantages of lower revision. However, UKA in older patients continues to be a viable option for isolated medial compartment osteoarthritis LEVEL OF EVIDENCE: Level III Propensity score matched study.

Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy

Purpose

High tibial osteotomy (HTO) is an effective treatment option in early osteoarthritis. However, preoperative planning and surgical execution can be challenging. Computer assisted three-dimensional (3D) planning and patient-specific instruments (PSI) might be helpful tools in achieving successful outcomes. Goal of this study was to assess the accuracy of HTO using PSI.

Methods

All medial open wedge PSI-HTO between 2014 and 2016 were reviewed. Using pre- and postoperative radiographs, hip-knee-ankle angle (HKA) and posterior tibial slope (PTS) were determined two-dimensionally (2D) to calculate 2D accuracy. Using postoperative CT-data, 3D surface models of the tibias were reconstructed and superimposed with the planning to calculate 3D accuracy.

Results

Twenty-three patients could be included. A mean correction of HKA of 9.7° ± 2.6° was planned. Postoperative assessment of HKA correction showed a mean correction of 8.9° ± 3.2°, resulting in a 2D accuracy for HKA correction of 0.8° ± 1.5°. The postoperative PTS changed by 1.7° ± 2.2°. 3D accuracy showed average 3D rotational differences of − 0.1° ± 2.3° in coronal plane, − 0.2° ± 2.3° in transversal plane, and 1.3° ± 2.1° in sagittal plane, whereby 3D translational differences were calculated as 0.1 mm ± 1.3 mm in coronal plane, − 0.1 ± 0.6 mm in transversal plane, and − 0.1 ± 0.6 mm in sagittal plane.

Conclusion

The use of PSI in HTO results in accurate correction of mechanical leg axis. In contrast to the known problem of unintended PTS changes in conventional HTO, just slight changes of PTS could be observed using PSI. The use of PSI in HTO might be preferable to obtain desired correction of HKA and to maintain PTS.

Return to sport following isolated opening wedge high tibial osteotomy

BACKGROUND

The purposes of the study are as follows: (1) examine the timeline of return to sport (RTS) following isolated high tibial osteotomy (HTO), (2) evaluate the degree of participation and function upon RTS and (3) identify reasons that patients do not return or discontinue participation in sport activity.

METHODS

Patients undergoing isolated HTO were reviewed retrospectively at a minimum of two years post-operatively. Patients completed a subjective sports questionnaire, a visual analog scale for pain, Single Assessment Numerical Evaluation, and a satisfaction questionnaire.

RESULTS

Thirty-eight patients (70.4%) were included at an average of 9.0 ± 3.3 years. Thirty-four patients (average age 42.7 ± 7.2 years, 90.0% with a Kellgren-Lawrence grade of III/IV) participated in sports within three years prior to surgery. Eighteen patients (52.9%) returned to the operating room by the time of final follow-up, including 13 patients (38.2%) who underwent salvage arthroplasty by 6.1 ± 3.6 years following HTO. Thirty patients (88.2%) returned to ≥1 sport at an average of 7.5 ± 5.0 months; however only 41.2% were able to return to preinjury level of participation.

CONCLUSIONS

In patients with medial osteoarthritis and varus deformity, isolated high tibial osteotomy provides a high rate (88.2%) of return to sport by 7.5 months postoperatively, yet only a fraction of patients returned to their preinjury level. HTO is not a definitive treatment option as nearly 40% of patients underwent knee arthroplasty by 6.1 years post-operatively. Patient expectations regarding return to sport can be appropriately managed with adequate preoperative patient education.

LEVEL OF EVIDENCE

IV.

Effects of a Medial Knee Unloading Implant on Tibiofemoral Joint Mechanics During Walking

The Atlas™ unicompartmental knee system is a second-generation extra-articular unloading implant for patients with mild to moderate medial knee osteoarthritis. The technology acts to reduce a portion of the weight-bearing load exerted on the medial knee during physical activity thereby, reducing the mechanical stress imposed on a degenerative joint. The purpose of the present study was to evaluate the effects of the Atlas™ on tibiofemoral joint mechanics during walking. A computer-aided design assembly of the Atlas™ was virtually implanted on the medial aspect of a previously validated finite element tibiofemoral joint model. Data for knee joint forces and moments from an anthropometrically matched male were applied to the model to quasi-statically simulate the stance phase of gait. Predictions of tibiofemoral joint mechanics were computed pre- and post-virtual implantation of the Atlas™. Compressive force in the medial tibiofemoral compartment was reduced by a mean of 53%, resulting in the decrement of mean cartilage-cartilage and cartilage-meniscus von Mises stress by 31% and 32%, respectively. The Atlas™ was not predicted to transfer net loading to the lateral compartment. The tibiofemoral joint model exhibited less internal-external rotation and anterior-posterior translation post-Atlas™, indicating a change in the kinematic environment of the knee. From a biomechanical perspective, extra-articular joint unloading may serve as a treatment option for patients recalcitrant to conservative care. Evaluation of mechanical changes in the tibiofemoral joint demonstrate the potential treatment mechanism of the Atlas™, in accordance with the available clinical data. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2149-2156, 2019.

Comparison of radiological features of high tibial osteotomy and tibial condylar valgus osteotomy

Background

The purpose of this study was to compare radiological features between high tibial osteotomy (HTO) and tibial condylar valgus osteotomy (TCVO), in order to define the radiological indication criteria for TCVO.

Methods

Thirty-two cases involving 35 knees that had undergone HTO and the same number that had undergone TCVO for knee osteoarthritis were retrospectively evaluated. Characteristics of both groups did not differ significantly. Lower limb alignment, bone morphology, joint congruity, and joint instability were measured in standing full-length leg and knee radiographs obtained before and after surgery.

Results

Radiological features in the TCVO group included greater frequencies of advanced knee OA grade, varus lower limb malalignment, depression of the medial tibial plateau, and varus-valgus joint instability compared to the HTO group before surgery. However, tibial morphology, alignment of the lower limb, and joint instability improved to comparable levels after surgery in both groups.

Conclusions

TCVO appears preferable in cases with advanced knee OA, destroyed or inclined medial tibial plateau, widened and subluxated lateral joint, and high varus-valgus joint instability.

Improved Methods to Measure Outcomes After High Tibial Osteotomy

Observational studies suggest high tibial osteotomy produces substantial improvements in knee loading and stability that can limit the progression of joint damage; decrease pain; improve function and quality of life; and delay the need for knee replacement surgery. It can be cost-effective in knee osteoarthritis. However, systematic reviews and clinical practice guidelines are unable to provide strong recommendations, because limited high-level evidence supports its therapeutic value versus other treatments. We describe findings suggesting it can improve outcomes important to knee joint structure and function, patient quality of life, and health care systems. Future clinical trials are warranted and required.

Long-term survival is similar between closed-wedge high tibial osteotomy and unicompartmental knee arthroplasty in patients with similar demographics

PURPOSE

Long-term clinical and radiographic results and survival rates were compared between closed-wedge high tibial osteotomy (HTOs) and fixed-bearing unicompartmental knee arthroplasty (UKA) in patients with similar demographics.

METHODS

Sixty HTOs and 50 UKAs completed between 1992 and 1998 were retrospectively reviewed. There were no significant differences in pre-operative demographics. The mean follow-up period was 10.7 ± 5.7 years for HTO and 12.0 ± 7.1 years for UKA (n.s.). The Knee Society knee and function scores, WOMAC, and range of motion (ROM) were investigated. The mechanical axis and femorotibial angle were evaluated. Kaplan-Meier survival analysis was performed (failure: revision to TKA) and the failure modes were investigated.

RESULTS

Most of the clinical and radiographic results were not different at the last follow-up, except ROM; ROM was 135.3° ± 12.3° in HTO and 126.8° ± 13.3° in UKA (p = 0.005). The 5-, 10-, 15-, and 20-year survival rates were 100%, 91.0%, 63.4%, and 48.3% for closed-wedge HTO, respectively, and 90.5%, 87.1%, 70.8%, and 66.4% for UKA (n.s.). The survival rate was higher than that for UKA until 12 years post-operatively but was higher in UKAs thereafter, following a remarkable decrease in HTO. The most common failure mode was degenerative osteoarthritic progression of medial compartment in HTO and femoral component loosening in UKA.

CONCLUSIONS

Long-term survival did not differ significantly between closed-wedge HTO and fixed-bearing UKA in patients with similar pre-operative demographics and knee conditions. The difference in post-operative ROM and failure mode should be considered when selecting a procedure.

LEVEL OF EVIDENCE

III.

Pain Deterioration Within 1 Year Predicts Future Decline of Walking Ability: A 7-Year Prospective Observational Study of Elderly Female Patients With Knee Osteoarthritis Living in a Rural District

Introduction

Knee osteoarthritis (KOA) is commonly a main cause of locomotive syndrome. Consequently, appropriate timing of intervention is clinically important.

Materials and Method

Fifty female patients of a primary care clinic in a rural district fulfilled the criteria for KOA and were recruited and underwent knee medical checkups. They initially underwent physical examination bilaterally of knees by an orthopedic surgeon, radiological evaluation, and they answered the outcome of Japanese Knee Osteoarthritis Measurement (JKOM). They were asked to answer JKOM 1 and 7 years after the initial checkup. Fourteen patients were lost to follow-up due to death or moving to a nursing home. Thirty-six patients were finally included and divided into 2 age-matched groups according to walking ability at the 7-year follow-up: group A, walking ability did not decline (n = 24), and group B, walking ability did decline (n = 12). The walking ability was measured as per ordinal classification as: 5 (walking without any aid), 4 (walking with a crutch), 3 (walking using walker), 2 (walking only possible in parallel bars), and 1 (wheelchair). We completed between-group comparisons of each of the 3 subsections of the JKOM (pain, limitation in mobility related to daily activity, and restriction of participation in social life and health perception), during each period.

Results

There were significant differences in JKOM pain score (12.9 vs 18.3, P = .0058) and total score (41.3 vs 55.8, P = .0093) between the groups at 1-year follow-up, even though base scores did not differ.

Discussion

Clinicians should pay attention to changes in perceived knee pain and should not continue prolonged conservative therapy in patients exhibiting rapid deterioration.

Conclusion

Female patients with KOA whose pain deteriorated within 1 year may require early intervention to prevent future decline in walking ability.

3D printing and high tibial osteotomy

High tibial osteotomy (HTO) is a relatively conservative surgical option in the management of medial knee pain. Thus far, the outcomes have been variable, and apparently worse than the arthroplasty alternatives when judged using conventional metrics, owing in large part to uncertainty around the extent of the correction planned and achieved.

This review paper introduces the concept of detailed 3D planning of the procedure, and describes the 3D printing technology that enables the plan to be performed.

The different ways that the osteotomy can be undertaken, and the varying guide designs that enable accurate registration are discussed and described. The system accuracy is reported.

In keeping with other assistive technologies, 3D printing enables the surgeon to achieve a preoperative plan with a degree of accuracy that is not possible using conventional instruments. With the advent of low dose CT, it has been possible to confirm that the procedure has been undertaken accurately too.

HTO is the ‘ultimate’ personal intervention: the amount of correction needed for optimal offloading is not yet completely understood.

For the athletic person with early medial joint line overload who still runs and enjoys life, HTO using 3D printing is an attractive option. The clinical effectiveness remains unproven.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170075.

Unicompartmental Knee Arthroplasty vs High Tibial Osteotomy for Knee Osteoarthritis: A Systematic Review and Meta-Analysis

BACKGROUND

Prior studies have compared unicompartmental knee arthroplasty (UKA) with high tibial osteotomy (HTO) suggesting that both procedures had good clinical outcomes. However, which treatment is more beneficial for unicompartmental knee osteoarthritis is still a controversy. The purpose of our study is to obtain postoperative outcomes of revision rate, complications, function results, range of motion (ROM), and pain between the 2 procedures.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed and study protocol was published online at PROSPERO under registration number CRD42016049316. We searched the databases MEDLINE, EMBASE, Cochrane Library, and Web of Science up to May 2017. Articles that directly compared postoperative outcomes of UKA to HTO were included.

RESULTS

A total of 10 comparative studies were included in our meta-analysis. UKA patients showed less revision rate, less complications, and less postoperative pain than HTO patients; however, HTO patients obtained more ROM. No significant difference was observed between the group accruing to the knee function scores and excellent/good surgical results.

CONCLUSION

UKA offers a safe and efficient alternative to osteoarthritis reduced postoperative pain, less postoperative complication, and revision. The 2 surgical techniques showed satisfactory function results for the patients; however, the HTO group achieved superior ROM compared to the UKA group. HTO may be suitable for patients with high activity requirements. Treatment options should be carefully considered for each patient in accordance with their age, body mass index, grade of osteoarthritis, and patients' activity levels.

Unicompartmental knee replacement - Current perspectives

Unicompartmental knee replacement (UKR) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee. However, certain aspects of the procedure are still debated. These areas of discussion include patient selection criteria, implant design and the discrepancy in survival rates between national registries and independent case series. These may contribute in limiting the more widespread acceptance of unicompartmental knee replacement. The aim of this paper is to review the up-to-date evidence on UKR and discuss the most relevant controversies regarding this procedure.

Unloading knee brace is a cost-effective method to bridge and delay surgery in unicompartmental knee arthritis

Background

Unloading knee braces can provide good short-term pain relief for some patients with unicompartmental osteoarthritis (UOA). Their cost is relatively small compared with surgical interventions. However, no previous studies have reported their use over a duration of 5 years or more.

Methods

Up to 8 years of prospective data were collected from 63 patients who presented with UOA. After conservative management with analgesia and physiotherapy, patients were offered an unloading brace. EQ-5D (EuroQol five dimensions) questionnaires were collected at baseline and after wearing the brace. Cost and quality-adjusted life years (QALYs) were compared with a total knee replacement (TKR) with an 8-month waiting duration and 8 years of results.

Results

Patients experienced a mean increase in EQ-5D of 0.42 with an average duration of wear of 26.1 months resulting in an increase of 0.44 in QALYs with a mean cost of £625. The adoption of an unloader knee brace was found to be a short-term cost-effective treatment option with an 8-month incremental cost effectiveness ratio of £9599. Compared with no treatment, the unloader knee brace can be considered cost effective at 4 months or more. At 8 years follow-up, the unloader knee brace demonstrated QALYs gain of 0.43 and with an incremental cost-effectiveness ratio of -£6467 compared with TKR.

Conclusion

Unloading knee braces are cost effective for the management of UOA. These findings strongly support the undertaking of further research into the long-term impact of unloading knee brace. The unloader knee brace has benefits to the National Health Service for capacity, budget, waiting list duration, frequency of surgery and reducing the required severity of surgical intervention.

Conversion of a unicompartmental knee arthroplasty to a total knee arthroplasty: can we achieve a primary result?

OBJECTIVES

Unicompartmental knee arthroplasty (UKA) is a potential treatment for isolated bone on bone osteoarthritis when limited to a single compartment. The risk for revision of UKA is three times higher than for total knee arthroplasty (TKA). The aim of this review was to discuss the different revision options after UKA failure.

MATERIALS AND METHODS

A search was performed for English language articles published between 2006 and 2016. After reviewing titles and abstracts, 105 papers were selected for further analysis. Of these, 39 papers were deemed to contain clinically relevant data to be included in this review.

RESULTS

The most common reasons for failure are liner dislocation, aseptic loosening, disease progression of another compartment and unexplained pain. UKA can be revised to or with another UKA if the failure mode allows reconstruction of the joint with UKA components. In case of disease progression another UKA can be added, either at the patellofemoral joint or at the remaining tibiofemoral joint. Often the accompanying damage to the knee joint doesn't allow these two former techniques resulting in a primary TKA. In a third of cases, revision TKA components are necessary. This is usually on the tibial side where augments and stems might be required.

CONCLUSIONS

In case of failure of UKA, several less invasive revision techniques remain available to obtain primary results. Revision in a late stage of failure or because of surgical mistakes might ask for the use of revision components limiting the clinical outcome for the patients. Cite this article: Bone Joint J 2017;99-B(1 Supple A):65-9.

Establishing Age-Specific Cost-Effective Annual Revision Rates for Unicompartmental Knee Arthroplasty: A Meta-Analysis

BACKGROUND

Improved survivorship has contributed to the increased use of unicompartmental knee arthroplasty (UKA) as an alternative to total knee arthroplasty (TKA) for unicompartmental knee osteoarthritis. However, heterogeneity among cost-effectiveness analysis studies comparing UKA to TKA has prevented the derivation of discrete implant survivorship targets. The aim of this meta-analysis was to determine the age-stratified annual revision rate (ARR) threshold for UKA to become consistently cost-effective for unicompartmental knee osteoarthritis.

METHODS

A systematic search was performed for cost-effectiveness analysis studies of UKA vs TKA. Selected publications were rated by evidence level and assessed for methodological quality. Target UKA survivorship values determined by sensitivity analysis were retrieved, converted to ARR, and combined by age category (<65, 65-74, and ≥75 years) to estimate age-specific cost-effectiveness thresholds.

RESULTS

Four studies met all inclusion criteria. All publications were evidence level I-B, with high methodological quality. Combined data indicated median threshold cost-effective ARR of 1.471% (interquartile range [IQR], 1.415-1.833; age <65), 1.135% (IQR, 1.011-1.260; age 65-74), and 1.760% (IQR, 1.660-2.880; age ≥75). Current revision rates are already below the cost-effective threshold for patients aged ≥75, but exceed recommended values in younger patients.

CONCLUSION

The findings indicate that implant survivorship is a limiting factor toward achieving cost-effective UKA in patients aged <65. Strategies to improve UKA survivorship, such as shifting procedures to high-volume centers, may render UKA cost-effective in younger patients. This presents an opportunity for resource reallocation within health systems to achieve cost-effective utilization of UKA across a broader population segment.