Femoral Neck Osteochondroma Managed With Partial Surgical Excision and Prophylactic Screw Fixation

Osteochondroma is the most common benign bone tumor, characterized by an osteocartilaginous outgrowth with cortical and medullary continuity to the parent bone. While proximal femoral involvement is relatively frequent, particularly in patients with hereditary multiple exostoses, an osteochondroma arising specifically from the femoral neck is uncommon and carries distinct clinical significance due to its intra-articular location. Such lesions can produce femoroacetabular impingement, restricted hip motion, labral and chondral injury, subluxation, acetabular dysplasia, snapping hip phenomena, nerve palsy, and premature osteoarthritis. The proximity of femoral-neck osteochondromas-especially those situated posteriorly or posteroinferiorly-to the deep branch of the medial femoral circumflex artery, the dominant vascular supply to the femoral head, introduces a unique surgical challenge: achieving complete tumor excision while safeguarding femoral-head perfusion to prevent avascular necrosis (AVN). We report the case of a 23-year-old woman who presented with limited range of motion of the left hip and discomfort during walking and running. Clinical examination revealed restricted terminal external rotation and extension. Radiographic and cross-sectional imaging (computed tomography (CT) and magnetic resonance imaging (MRI)) demonstrated a stalk-like osseous lesion arising from the posteroinferior femoral neck, covered by a cartilaginous cap, with clear cortical continuity to the parent bone-findings consistent with osteochondroma. The joint capsule was thinned and indented by the mass. Given the symptomatic intra-articular location and proximity to the femoral-head blood supply, surgical excision was performed without formal surgical dislocation of the hip, using a posterior approach. The piriformis was released to enhance exposure, and the lesion was resected piecemeal using a saw and osteotomes, with careful preservation of the medial femoral circumflex artery. The deep inferior portion of the lesion could not be fully excised without risking vascular compromise; therefore, a partial resection was performed to restore functional range of motion while preserving femoral-head perfusion. Prophylactic cannulated screw fixation was performed to reinforce the femoral neck and permit immediate postoperative weight-bearing.