Donor site morbidity after the harvest of microvascular flaps from the medial and lateral femoral condyle region: Objective, radiologic, and patient-reported outcome of a multi-center trial

Summary Background With the experience-based hypothesis of low donor site morbidity (DSM) for free flaps from the distal femur, this cohort study aimed to evaluate the DSM according to objective and reproducible criteria. Methods One hundred and fifty-six patients who had a flap harvest from either the medial or lateral femoral condyle region between 2005 and 2017 were included. A retrospective chart review was performed for all patients. In total, 97 patients were available for a follow-up examination. Outcomes were assessed according to objective (Knee Society Score; Larson Knee Score; OAK Score; 0–100 points), patient-reported (IKDC Score; KOOS Score; 0–100 points), and radiologic criteria (Kellgren and Lawrence Score; MRI Osteoarthritis Knee Score). Results The median follow-up time was 1,529 days (range: 248–4,810). The mean Knee Society Score (94.8 ± 10.1), Larson Knee Score (94.5 ± 10.1), and OAK Score (95.5 ± 6.6) showed nearly unimpaired knee function. The overall patient-reported DSM was low (IKDC Score: 86.7 ± 17.4; KOOS Score: 89.3 ± 17.1). Osteochondral (OC) flaps had a significantly higher DSM, regardless of the donor site. Bone flaps did not show any relevant radiologic morbidity in the Kellgren and Lawrence Score. Besides the procedure-associated cartilage lesions at the OC donor sites, MRI Osteoarthritis Knee Score did not show any significant presence of further knee pathologies in the bilateral MRI Scans. The obvious cartilage lesions did not have a relevant impact on the knee function of most patients. Conclusion The DSM for bone and soft-tissue flaps from the femoral condyle region is negligible. OC flaps are associated with a significantly higher DSM, although a clinically relevant impact on knee function was not evident in the majority of patients.