Introduction
When opting for a vascularized bone graft in upper and lower extremity reconstruction, the medial femoral condyle (MFC) flap emerges as a reliable choice for small bone defects or calcitrant nonunion. This flap can be harvested based on various components, such as the chimeric osteocutaneous flap, which offers versatility and adaptability in surgical procedures. However, lower extremity bone reconstructions usually undergo the weight bearing challenge. The MFC is characterized with a high cancellous bone ratio which cannot afford high mechanical support. In this study, we present the experiences of eight patients who received MFC reconstruction in the lower extremity.
Patients and Methods
From August 2014 to June 2023, a lower extremity reconstruction using the MFC flap was performed in eight cases. All patients are male, aged from 17 to 63 years old (Median 46 years old). Five patients involved open fractures of the tibia bone complicated by a bone defect (Defect length from 1 to 6 cm, median: 3.2 cm; segmental defect:2, partial cortex contact:3). All fracture sites were fixed with a rigid locking plate or intramedullay nail fashion. 4 chimeric osteocutaneous flaps and 1 chimeric periosteocutaneous flap with allograft were designed. 2 patients had talus sarcoma, chimeric osteocutaneous flaps were inset after tumor ablation, 1 patient received pedicled periosteocancellous flap for calcitrant nonunion of the distal end of femoral bone allograft. Regarding possible donor site morbidity, the maximum bone graft size was 5 cm.
Results
The follow-up period was from 5 to 59 months. Among the long bone reconstruction group, one flap experienced skin flap part failure and was salvage with a distal-based hemisoleus muscle flap. All the components of bone and periosteum survived. However, the bone union rate was 75% because one vascularized graft displacement without revision in the talus and long allograft with poor regeneration in the femur bone. The time to bone union ranged from 5 to 18 months (Median 8 months). Regarding the time to full weight bearing, the duration was from 5 to 15 months (Median 6 months).
Conclusions
Based on our limited case experience, the MFC flap could serve as an acceptable option for lower extremity reconstruction in selected patients with small bone defects. Rigid fixation or partial bone cortex contact, which can afford mechanical support, is a benefit for bone union.

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