Surgical hip dislocation through a direct lateral approach: A cadaveric study of vascular danger zones.

OBJECTIVE: There is limited information on the potential danger to the vascularity of the femoral head during surgical dislocation of the hip using the direct lateral approach. The objective of this study was to investigate the topographical anatomy of the medial femoral circumflex artery (MFCA), the primary source of blood supply to the femoral head, in relationship to the direct lateral approach.
METHODS: Seven unembalmed cadaver hips had dye injection into either the profunda femoris artery or the MFCA. Surgical hip dislocation was then performed through a direct lateral approach, noting the danger zones to the MFCA branches during each step of the exposure.
RESULTS: None of the MFCA branches were found to cross the anterior surgical field superficial to the capsule. The deep (main) branch of the MFCA pierced the inferior capsule at the level of the lesser trochanter after emerging posterior to iliopsoas tendon. Ascending branches up the medial femoral neck were identified at this level. The deep branch then coursed posteriorly terminating in a variable number of vessels ascending the posterior femoral neck. Dislocation of the femoral head did not stretch or alter the course of the deep branch of the MFCA.
CONCLUSION: Safe surgical hip dislocation preserving the MFCA can be performed though a direct lateral approach as long as the inferomedial portion of the anterior capsule is preserved (main branch of the MFCA pierces the capsule at this level). Extracapsular injury is possible from inadvertent dissection at the level of the lesser trochanter or aggressive retraction on the iliopsoas. The posterior capsule should be left intact and instrumentation around the posterior neck should be avoided.