Assessment of femoral head and head-neck junction perfusion following surgical hip dislocation using gadolinium-enhanced magnetic resonance imaging: a cadaveric study.

BACKGROUND: The purpose of the present study was to quantify perfusion to the femoral head and head-neck junction using gadolinium-enhanced magnetic resonance imaging following three surgical dislocations of the hip (trochanteric flip osteotomy, standard posterior approach, and modified posterior approach).

METHODS: The medial femoral circumflex artery was cannulated in fifty fresh-frozen cadaveric hips (twenty-five pelvic specimens). One hip on each pelvic specimen was randomly chosen to undergo one of the three surgical dislocations, and the contralateral hip was used as a control. Gadolinium enhancement on the magnetic resonance imaging scan was quantified in both the femoral head and head-neck junction by volumetric analysis using custom magnetic resonance imaging analysis software. A polyurethane compound was then injected, and gross dissection was performed to assess the extraosseous vasculature.

RESULTS: Magnetic resonance imaging quantification revealed that the trochanteric flip osteotomy group maintained almost full perfusion (mean, 96% for the femoral head and 98% for the head-neck junction). The standard posterior approach almost completely compromised perfusion (mean, 4% for the femoral head and 8% for the head-neck junction). Six specimens in the modified posterior approach group demonstrated partial perfusion (mean, 32% in the femoral head and 26% in the head-neck junction). Three specimens in the modified posterior approach group demonstrated almost full perfusion (mean, 96% in the femoral head and 97% in the head-neck junction). Gross dissection revealed that all specimens in the standard posterior approach group and seven of ten in the modified posterior approach group sustained disruption of the ascending branch of the medial femoral circumflex artery. All specimens in the standard posterior approach group demonstrated disruption of the inferior retinacular artery. The inferior retinacular artery remained intact in nine of ten specimens in the modified posterior approach group. One specimen in the modified posterior approach group that had disruption of both the ascending medial femoral circumflex artery and inferior retinacular artery demonstrated a substantial decrease in perfusion (7% in the femoral head and 5% in the head-neck junction).

CONCLUSIONS: The trochanteric flip osteotomy preserves the vascular supply to the femoral head and head-neck junction. The standard posterior approach disrupts the vascular supply and should be completely abandoned for surgical hip dislocation. Despite reduced enhancement, substantial perfusion of the femoral head and head-neck junction was present in the modified posterior approach group, likely because of the preservation of the inferior retinacular artery. The modified posterior approach produced variable results, indicating that improvement to the modified posterior approach is needed.

CLINICAL RELEVANCE: Our study provides previously unreported quantitative magnetic resonance imaging data on the perfusion to the femoral head and head-neck junction during common surgical approaches to the hip.