The Medial Metaphyseal Periosteal Artery (MMPA): An Alternate Pedicle for the Medial Femoral Trochlea Flap

The patient was a 19-year-old, right-handed man who sustained a left scaphoid proximal pole fracture after a fall. The patient did not seek treatment for the injury and went on to develop avascular necrosis and collapse of the scaphoid proximal pole. He presented to our facility with a painful nonunion and no radiographic signs of early osteoarthritis. He underwent a proximal pole reconstruction using an MFT osteochondral free flap. The elevation of the flap was carried out using the standard technique described by Higgins and Bürger. During dissection of the pedicle, the transverse branch of the DGA was barely discernable and was not reaching the trochlea. A dominant periosteal artery was identified lying anteriorly on the femur; it was directly supplying the trochlear region where the chondral flap was to be harvested. The sterile tourniquet was released before vessel dissection to verify the dominant flow. The flap was then successfully elevated on this alternate artery, dissected in a retrograde fashion to its origin on the superficial femoral artery, while preserving a thin cuff of periosteum around the vessel. This artery, accompanied by 2 venae comitantes, was of adequate size for end-to-side anastomosis with the radial artery (Fig. 1). The osteochondral flap was inset to the proximal scaphoid with a cannulated compression screw. At 12 weeks, the reconstructed scaphoid was united on computed tomography scan (Fig. 2). The patient returned to normal work and activities without wrist or knee pain.

The anatomical work of Iorio et al addressed the perfusion of corticocancellous bone flaps harvested from the medial femoral condyle region. The authors described the presence of a previously unnamed vascular pedicle providing additional perfusion to the metadiaphyseal area of the distal femur.^, This medial metaphyseal periosteal artery (MMPA) originates directly from the superficial femoral artery in the adductor hiatus, proximal to the origin of the DGA. It then courses medially in the periosteum of the medial femur and consistently forms an anastomotic periosteal network with the transverse branch of the DGA. Some variations in the pattern of branching of these vessels have been described.

In this case, the MMPA was clearly the dominant pedicle supplying the trochlear region and the chondral flap was successfully raised on this new vessel. When harvesting this flap, the authors typically use a sweeping curvilinear incision starting at the Hunter canal and extending distally and anteriorly to the midpoint between the medial border of the patella and medial femoral condyle, as described by Higgins et al. The incision usually measures 10 to 15 cm. When harvesting the MMPA artery as the flap main pedicle, it may be necessary to extend the proximal part of the incision to trace the MMPA vessels back to where they lift off the periosteum and join the superficial femoral artery. This facilitates microsurgery because the pedicle is not embedded in the periosteum at this level.

The incidence of this anatomical variant remains unknown. This uncommon presentation provides sufficient pedicle length in wrist reconstruction and allows preservation of the DGA at the donor site. To our knowledge, this is the first report of the MMPA artery as an alternate pedicle to the MFT flap. It can safely be based on the MMPA when dominant.