Arterial Perfusion of the Medial Femoral Trochlea Flap Examined by Micro-Computed Tomography Angiography.

Abstract

Purpose: The medial femoral trochlea (MFT) flap is a source of vascularized articular cartilage that has most commonly been used for reconstruction of proximal pole scaphoid nonunions and lunate osteonecrosis in Kienbock disease. This study aimed to describe the arterial perfusion of the MFT.

Methods: Selective injection of the descending genicular artery (DGA) was performed with radiopaque dye in eight cadaveric lower extremities. Micro-computed tomography was performed on the medial femoral condyle including the MFT segment, with digital analysis quantifying vessel location and internal diameter within the territory of the MFT flap.

Results: All specimens had adequate perfusion up to the MFT from the transverse branch of the DGA. The transverse branch and longitudinal branches of the DGA were of similar caliber (0.45 ± 0.19 and 0.49 ± 0.29 mm, respectively). The segment of bone and cartilage included in MFT harvest had an average of 5.9 ± 1.2 terminal periosteal vessels and 2.8 ± 1.9 nutrient vessels. The greatest number of nutrient vessels to the MFT were contained within 6.3 ± 2.19 mm from the cartilage margin. More nutrient vessels were found penetrating the cortex on the proximal aspect of the trochlea. The nutrient vessels demonstrated a consistent pattern of perfusion penetrating the cortex and coursing perpendicular to the surface of the femur.

Conclusions: The MFT flap is reliably perfused by the transverse branch of the DGA with a rich supply of periosteal and nutrient vessels adjacent to cartilage. These vessels often collateralize with terminal vessels of the longitudinal branch. Periosteal and nutrient vessels to the flap are within 6.3 mm from the edge of the cartilage, which translates to a safe margin for osteotomy/flap harvest.

Clinical relevance: Understanding MFT microperfusion guides optimal flap harvest by maximizing the capture of osseous perforators.