Balancing in Unicompartmental Knee Arthroplasty: Balancing in Flexion or in Extension?

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.

The efficacy and safety of patient-specific instrumentation versus conventional instrumentation for unicompartmental knee arthroplasty: Evidence from a meta-analysis

BACKGROUND

The aim of this study was to compare the efficacy and safety of patient-specific instrumentation (PSI) and conventional instrumentation (CI) for unicompartmental knee arthroplasty. Our hypothesis was that the PSI would be superior to CI in improving implant positioning and clinical function.

METHODS

We searched electronic databases (PubMed, Web of Science, Embase, and Cochrane) to identify relevant studies published before July 1, 2023 that met our inclusion criteria. The identified reports at least included one of the following outcome variables: coronal component alignment, sagittal component alignment, number of outliers, hip-knee-ankle angle, postoperative complications, operative time and knee joint functional evaluation. For dichotomous variables, we calculated the risk ratio and its 95% confidence interval (CI). For continuous variables, we calculated the mean difference (MD) and its 95% CI. Heterogeneity of the included studies was assessed using the standard chi-square test. Meta-analyses were performed using RevMan 5.4. software. The meta-analysis was registered with PROSPERO (No. CRD42023454160).

RESULTS

A total of 9 articles were included in the analysis, consisting of 4 randomized controlled trials and 5 cohort studies. The study population comprised 494 patients, with 262 in the PSI group and 232 in the CI group. Our findings demonstrate that the PSI group exhibits superior tibial component coronal alignment compared to the CI group (MD = -0.66, 95% CI: -1.21 to -0.12, P = .02). Conversely, the CI group demonstrates better femoral component coronal alignment than the PSI group (MD = 0.89, 95% CI: 0.17-1.60, P = .01). No significant between 2 groups differences were observed in tibial component sagittal alignment, femoral component sagittal alignment, tibial coronal axis outliers, tibial sagittal axis outliers, femoral coronal axis outliers, femoral sagittal axis outliers, postoperative complications, operative time, hip-knee-ankle angle, and postoperative knee joint function score.

CONCLUSIONS

Our study findings suggest that the PSI confer an advantage in achieving superior tibial component coronal alignment, whereas the CI associated with better femoral component coronal alignment. However, no significant differences were observed between the groups in terms of other parameters. Future studies with larger sample sizes are needed to validate these findings.

Enhanced recovery after surgery (ERAS) protocol in geriatric patients underwent unicompartmental knee arthroplasty: A retrospective cohort study

The enhanced recovery after surgery (ERAS) pathway was formulated with the aim to reduce surgical stress response, alleviate pain and guarantee the best-fit experience of patients' perioperative period. However, the application of ERAS in geriatric patients who underwent unicompartmental knee arthroplasty (UKA) was relatively lacking. We hypothesize that UKA patients can benefit from the ERAS protocol. A total of 238 patients were recruited in this retrospective study from August 2018 to December 2021, and Oxford phase III UKA was applied to all patients. ERAS pathway included nutrition support, anesthesia mode, interoperative temperature, and blood pressure control, application of tranexamic acid, early initiation of oral intake and mobilization, and pain management. Demographic data, operation-relative variables, and postoperative complications were analyzed. Forgotten Joint Scores, Oxford Knee Score, Lysholm score, numerical rating scale, and knee range of motion were introduced to estimate the activity function and pain of surgical knee, and these variables were compared between the 2 groups. There were 117 patients in the ERAS group and 121 patients in the traditional group, respectively. The ERAS group had a shorter length of surgical incision and less intraoperative blood loss. Postoperative hemoglobin and albumin of patients in the ERAS group were better than those in the traditional group (P < .05), after 17.0 ± 10.8 months follow-up, the numerical rating scale, Lysholm, Oxford Knee Score, Forgotten Joint Scores, and knee range of motion of patients in the ERAS group were significantly better than the traditional group. The length of hospital stay for patients who underwent ERAS was 11.7 ± 3.8 days and the postoperative complication rate was lower for the ERAS group patients (P = .000 and 0.031). ERAS can reduce the length of hospital stay, and patients can achieve excellent postoperative knee function. The formulation and implementation of the ERAS protocol require good collaboration across multiple disciplines, as well as a deep understanding of the existing clinical evidence and the concept of the ERAS program.