Background <p>Multiple Hereditary Exostoses (MHE) is a rare autosomal-dominant disorder characterized by the development of multiple osteochondromas. While often asymptomatic, these lesions can cause pain and functional limitations due to mechanical impingement or malignant transformation. Osteochondromas of the femoral neck pose unique challenges due to their proximity to critical neurovascular and weight-bearing structures.</p> Case presentation <p>We present the case of a 43-year-old Italian woman with MHE who developed severe femoroacetabular impingement due to a large osteochondroma located at the inferomedial aspect of the left femoral neck. Surgical management included a safe surgical dislocation of the hip via trochanteric flip osteotomy, followed by complete resection of the lesion. Given the extensive cortical defect resulting from resection, a prophylactic sliding hip screw (SHS) system was implanted to prevent postoperative femoral neck fracture. Given the extensive resection and loss of the inferomedial femoral neck cortex, the postoperative recovery included initial non-weight bearing and a structured rehabilitation program. Histology confirmed a benign osteochondroma. At seven years postoperatively, the patient reported sustained pain relief, restored function, and preserved joint range of motion, with no radiographic or clinical complications.</p> Conclusions <p>In cases of large femoral neck osteochondromas in MHE patients, surgical dislocation ensures safe and complete excision. When resection leads to substantial cortical weakening, prophylactic fixation with an SHS construct may offer mechanical stability, reduce fracture risk, and facilitate early mobilization. This combined approach may be particularly beneficial for joint preservation in young adults with structurally compromised femoral necks.</p>