Mid-term clinical outcomes of one and two patient-specific mini-implants for focal (osteo-)chondral lesions of the distal femur

OBJECTIVES: Patient-specific mini-metal implants may represent a treatment option for middle-aged patients with focal (osteo-)chondral lesions of the distal femur when biological repair has failed or when other individual risk factors make biological repair unlikely to succeed. Both single-implant approaches for one- and dual-implant approaches for two separate lesions in the same knee were investigated. This study evaluates the clinical performance of these implants for one or two lesions in one knee. METHODS: This retrospective single-center study was conducted using prospectively collected data of consecutive patients treated with one or two implants (Episealer Implant) with a mean follow-up of 38 months. The Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, adverse events, and conversions to unicompartmental or total knee arthroplasty were assessed. RESULTS: Statistically significant improvements in all KOOS subscales and VAS pain score compared to the preoperative values were observed in both groups (one implant n = 45; two implants n = 48; all p < 0.001). KOOS symptoms improved from 48.7 ± 17.9 to 74.3 ± 21.6 in the one-implant group and from 44.7 ± 15.0 to 66.0 ± 24.8 in the two-implant group. Similar improvements were observed across all remaining KOOS subscales. The comparison between the two groups revealed slightly better improvements for the one-implant group. Implant survival according to Kaplan-Meier analysis was 88.1% for the one-implant group (number at risk = 21) and 83.4% for the two-implant group (number at risk = 27) after 60 months. CONCLUSION: Patient-specific mini-metal implants may represent a viable treatment option for middle-aged patients when biological repair is not feasible. Within the limitations of this study, the findings suggest that this approach can be considered for patients with one as well as patients with two (osteo-)chondral lesions. An acceptable implant survival was observed, regardless of lesion count. LEVEL OF EVIDENCE: III.