Obesity increases the risk of conversion to total knee arthroplasty after unicompartimental knee arthroplasty: a meta-analysis

Unicompartmental knee arthroplasty in obese patients, poorer survivorship at 15 years

Introduction

The preclusion of obese patients from unicompartmental knee arthroplasty (UKA) has increasingly been challenged. This study aimed to evaluate the impact of Body Mass Index (BMI) on UKA at 15-year follow-up.

Materials and methods

169 unilateral UKA patients from 2003 to 2007 were followed-up prospectively for at least 15 years. 70 patients were left for analysis after accounting for patient demise, revision surgery and loss to follow-up. 48 of these patients (69%) were in the Control group (BMI <30 kg/m2) and 22 (31%) were in the Obese group (BMI ≥30 kg/m2). Patients were assessed before and after operation using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), and Physical (PCS) and Mental (MCS) component of the Short Form 12. Survivorship analysis was also performed.

Results

Obese patients went through UKA at an earlier age than the non-obese patients (54.7 ± 4.7 years compared to 59.9 ± 7.8 years, p = 0.005). At 2, 10, and 15-year follow-up, both groups achieved clinically significant improvements in outcomes. There was no significant association found between obesity and outcome using multiple linear regression. While propensity matching found PCS improvement at 2 years to be greater in obese patients, no significant association between obesity and 15-year outcome was found. All 13 patients who required revision, underwent total knee arthroplasty (TKA). The overall 15-year survivorship was 74.2% within the obese group and 92.4% within the control group.

Conclusion

Compared to non-obese patients, obese patients had poorer 15-year survivorship with greater odds of requiring revision surgery. However, assuming implant survival, obese patients can expect a non-inferior outcome relative to their non-obese counterparts in all patient reported outcome measures 15 years after surgery.

Trends in unicompartmental knee arthroplasty among 138 international experienced arthroplasty knee surgeons

Purpose

Unicompartmental knee arthroplasty (UKA) is an established option for treating isolated unicompartmental knee osteoarthritis (OA), but controversies still exist about patient selection, indications, perioperative management and alignment goals. This survey was designed to understand the current trends of experienced arthroplasty knee surgeons performing UKA.

Methods

An online questionnaire was created with SurveyMonkey® to assess global tendencies in the utilization of UKA. A link to the survey was shared with all ESSKA (European Society for Sports Traumatology, Knee Surgery and Arthroscopy) members. The questionnaire consisted of free and multiple-choice questions and was divided into four sections: demographic information, the surgical activity of the respondents, indications for surgery and postoperative alignment goals.

Results

A total of 138 ESSKA members from 34 different countries completed the survey. A total of 81 % of the responders performed fewer than 50 UKAs per year; 53 % of UKAs represented less than 20 % of their knee replacements; 71 % used mainly or only fixed-bearing implants; 81 % performed UKA in a shorter time compared to TKA; and 61 % and 72 % were interested in custom-made UKA and robotics, respectively. Thirty-six percent considered a minimum postoperative alignment of 0° for medial UKA, and 32 % considered 10° as the maximum valgus deformity for lateral UKA. Fifty-five percent had no minimum age cut-off, 47 % had no BMI cut-off, and 57 % believed TKA was better than UKA in knees with concomitant high-grade patellofemoral OA. Approximately 50 % of the surgeons desired a coronal alignment that was the same as the predegeneration alignment.

Conclusion

A high level of agreement was reached regarding the following: preference for fixed-bearing UKAs, lower surgical time for UKA compared to TKA, interest in custom-made and robotic UKAs, no age and weight cut-off, TKA preferred in the presence of patellofemoral OA, and a final alignment goal of the predegenerative state both for medial and lateral. There was no agreement regarding length of stay, rehabilitation protocol, preoperative varus and valgus cut-off values, and treatment in cases of absence of anterior cruciate ligament or previous osteotomy.

A BMI above 30 results in satisfying outcomes in patients undergoing fixed-bearing lateral unicompartmental knee arthroplasty

PURPOSE

The purpose of this study is to analyse the effect of BMI on clinical outcomes of cemented fixed-bearing lateral unicompartmental knee arthroplasty (UKA) on a 2- to 12-year follow-up.

METHODS

Between January 2010 and January 2020, a total of 103 lateral UKAs were implanted. The Oxford Knee Score (OKS) and the Western Ontario and McMaster University Osteoarthritis Index for pain, stiffness, function, and total score were administered to estimate patients' overall health status pre- and post-operatively. Results were considered good or excellent for WOMAC values > 85 points and OKS > 40 points. Survivorship, described with Kaplan-Meier method, was defined as the lack of revision at the latest follow-up. Complications or further operations were recorded. p values of < 0.05 were considered significant.

RESULTS

One hundred one lateral UKAs were assessed at a mean follow-up of 77.8 months. No patients underwent revision, but 2 patients (2, 0%) developed aseptic loosening of the implant 2 and 5 years after surgery but for clinical reasons neither undergo revision (5-year survivor 97.2%). Overall satisfaction was generally high, with excellent scores in all WOMAC subscales and OKS for all BMI groups. Considering the pain subscale (WOMAC pain), patients with normal weight and overweight achieve excellent results more frequently [10 (25.64%) vs 10 (23.81%) p = 0.026] than obese patients (n = 0); on the other hand, considering the quality of life (WOMAC QoL), obese patients most frequently reach excellent values, even statistically significant [n = 15 (75.00%) p = 0.040].

CONCLUSION

Although obesity has historically been described as a contraindication to UKA, improved outcomes with modern UKA implant designs have challenged this perception. Therefore, the classic contraindication of UKAs in patients with BMI > 30 kg/m² may not be justified. According to the present study, lateral UKA patients with BMI > 30 kg/m² had satisfactory patient-reported outcome measures compared to non-obese patients on a long term with survival rates comparable to medial UKA. Obese patients should not be excluded from the benefit of lateral UKA surgery.

Pain Course after Total Knee Arthroplasty within a Standardized Pain Management Concept: A Prospective Observational Study

BACKGROUND

Joint replacement surgeries have been known to be some of the most painful surgical procedures. Therefore, the options for postoperative pain management are of great importance for patients undergoing total knee arthroplasty (TKA). Despite successful surgery, up to 30% of the patients are not satisfied after the operation. The aim of this study is to assess pain development within the first 4 weeks after TKA in order to gain a better understanding and detect possible influencing factors.

METHODS

A total of 103 patients were included in this prospective cohort study. Postoperative pain was indicated using a numeric rating scale (NRS). Furthermore, demographic data and perioperative parameters were correlated with the reported postoperative pain.

RESULTS

The evaluation of postoperative pain scores showed a constant decrease in the first postoperative week (mean NRS score of 5.8 on day 1 to a mean NRS score of 4.6 on day 8). On day 9, the pain increased again. Thereafter, a continuous decrease in pain intensity from day 10 on was noted (continuous to a mean NRS score of 3.0 on day 29). A significant association was found between postoperative pain intensity and gender, body mass index (BMI), and preoperative leg axis.

CONCLUSIONS

The increasing pain score after the first postoperative week is most likely due to more intensive mobilization and physiotherapy in the rehabilitation department. Patients that were female, had a low BMI, and a preoperative valgus leg axis showed a significantly higher postoperative pain scores. Pain management should consider these results in the future to improve patient satisfaction in the postoperative course after TKA.

Patellofemoral arthroplasty: obesity linked to high risk of revision and progression of medial tibiofemoral osteoarthritis

PURPOSE

The purpose of this study was to determine the effect of obesity on patient outcome, procedure failure rate and osteoarthritis (OA) progression in the tibiofemoral compartments in a series of isolated patellofemoral arthroplasty (PFA) performed with a third-generation implant.

METHODS

The study population was patients who had undergone third-generation PFA at a specialized orthopedic center between 2007 and 2017. Patients were categorized by body-mass index (BMI) as obese (O, BMI > 30 kg/m²) or nonobese (NO, BMI < 30 kg/m²). Preoperative and postoperative clinical and functional assessment included knee range of motion, Knee Society Score (KSS), University of California Los Angeles (UCLA) Activity Score, Tegner Activity Level Scale, and visual analogue scale (VAS) for pain. Preoperative and postoperative radiographs were evaluated for progression of tibiofemoral compartment OA, changes in patellar height and in knee coronal alignment. Multiple logistic regression models were used to assess the effect of BMI on outcomes together with other covariates.

RESULTS

A total of 120 PFAs with a mean follow-up of 6.9 ± 2.5 years were included: 25 in the O group and 95 in the NO group. Significant improvement was noted in in knee range of motion (P < 0.001), clinical and functional KSS (P < 0.001), UCLA Activity Score (P < 0.001), Tegner score (P < 0.001) and VAS pain (P < 0.001) without inter-groups differences. Worsening of the medial Kellgren-Lawrence (KL) grade (but not the lateral KL grade) was more frequent in the O than the NO group during the follow-up period (P = 0.014). Failure occurred in 4.2% of NO and in 20% of O group patients; the difference was solely due to failure because of OA progression in the tibiofemoral compartment (16% in the O group). There were no between group differences in the failure rate for any cause other than OA progression (4.2% in the NO group, 4.0% in the O group).

CONCLUSIONS

An equal improvement in function after PFA was noted in both obese and nonobese patients; however, the high failure rate due to OA progression in the medial tibiofemoral compartment warrants caution when considering PFA in obese patients.