Focal articular surface replacement of knee lesions after failed cartilage repair using focal metallic implants: A series of 132 cases with 4-year follow-up

High degree of consensus amongst an expert panel regarding focal resurfacing of chondral and osteochondral lesions of the femur with mini-implants

INTRODUCTION

The rationale for the use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions is still under debate. The evidence supporting best practise guidelines is based on studies with low-level evidence. A consensus group of experts was convened to collaboratively advance towards consensus opinions regarding the best available evidence. The purpose of this article is to report the resulting consensus statements.

METHODS

Twenty-five experts participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted via an online survey of two rounds, for initial agreement and comments on the proposed statements. An in-person meeting between the panellists was organised during the 2022 ESSKA congress to further discuss and debate each of the statements. A final agreement was made via a final online survey a few days later. The strength of consensus was characterised as: consensus, 51-74% agreement; strong consensus, 75-99% agreement; unanimous, 100% agreement.

RESULTS

Statements were developed in the fields of patient assessment and indications, surgical considerations and postoperative care. Between the 25 statements that were discussed by this working group, 18 achieved unanimous, whilst 7 strong consensus.

CONCLUSION

The consensus statements, derived from experts in the field, represent guidelines to assist clinicians in decision-making for the appropriate use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions.

LEVEL OF EVIDENCE

Level V.

Low local curvature index and history of previous surgery are risk factors for revision in focal metallic inlay implants

BACKGROUND

Focal chondral defects are debilitating lesions with poor healing potential. Focal metallic inlay implants were developed as a salvage procedure, whose reoperation causes and risk factors for revision are still debatable. The aim of this study is to analyze the local subchondral curvature matching of focal metallic inlay implants and its effects on survival and clinical results.

METHODS

Patients operated with a knee focal metallic inlay resurfacing implant between 2014 and 2017 were eligible. Surgery was indicated for painful, focal, full-thickness cartilage lesions that had failed alternative treatments. Inclusion criteria were patients treated for a lesion ≤ 5 cm2 in the femoral condyle, aged 40-65 years, with complete surgical records and a knee CT scan. The curvature index (Kindex) was calculated as the ratio of the mean curvature of the implant (K1) to the mean curvature of the subchondral bone (K2).

RESULTS

Sixty-nine patients were included, of which 60.9% were female. Mean age was 54.8 ± 6.0. Seven patients (10.1%) underwent revision surgery. When adjusted for age and sex, lesion size was not significantly correlated to revision in a multivariate regression model, while previous surgery and smaller K index were. A positive history for previous surgery was significantly correlated with worse clinical outcomes in surviving patients.

CONCLUSION

A positive history of previous knee surgery and a low local curvature index are risk factors for revision after focal metallic inlay implant resurfacing. Patients with a history of knee surgery should be counseled on the advantages and disadvantages before undergoing a focal resurfacing procedure.

Femoral condyle resurfacing using an inlay metal implant: low revision rate of 266 patients in a 5-10 years follow-up

PURPOSE

To assess the clinical outcome and survival of an inlay resurfacing prosthesis for focal femoral condyle chondral and osteochondral defects.

METHODS

Two hundred sixty-six patients (mean age, 38.25 years; range 25-56 years) with symptomatic femoral condyle chondral and osteochondral defects were reviewed. The mean follow-up period was 7.3 years (range 5-10 years). The medial femoral condyle was involved in 229 and the lateral condyle in 37 patients. Previous cartilage surgery was done in 235 patients. All patients were treated with focal femoral condyle resurfacing with the HemiCAP^® device. The preoperative and the last follow-up values of the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), 36-item Short Form Survey (SF-36) and Visual Analogue Scale (VAS) were examined. Complications, reoperation rate and survival were analyzed.

RESULTS

At the last follow-up, all clinical score values showed significant improvement as compared with the corresponding preoperative values (p < 0.001). Age presented a negative correlation with KOOS (p = 0.03) and SF-36 improvement (p = 0.014). Kellgren-Lawrence grade influenced OKS (p = 0.036). BMI, gender, side, medial or lateral condyle and size did not affect the outcome. Patients who had previous biological cartilage procedures demonstrated better clinical improvement in comparison with those that did not have prior surgery (p < 0.05). Survival was 96.2% at 10 years, using as endpoint implant revision or/and progression of osteoarthritis. The cumulative hazard for any-reason reoperation was 12.0%.

CONCLUSIONS

Femoral condyle resurfacing using the HemiCAP^® device is an effective treatment option to address focal chondral and osteochondral defects. It can be successfully used either as a primary procedure or after prior biological cartilage reconstruction. Subjective clinical outcomes are expected to be good to excellent in mid- to long term, while reoperation and revision rates are low. Progression of osteoarthritis is the most common mode of failure; thus, patient selection is very important.

LEVEL OF EVIDENCE

Level IV, retrospective case series.