Osteochondromas are the most common benign bone tumours and are typically asymptomatic. Femoral neck involvement is uncommon and may lead to femoroacetabular impingement or mechanical hip pain [1-5]. Imaging plays a crucial role in diagnosis, demonstrating continuity of the cortex and medullary canal and excluding malignant transformation ^[6]. (Figs. 1-6) Surgical excision is indicated in symptomatic cases. However, resection of femoral neck lesions may compromise structural integrity and increase fracture risk ^[7,8]. Prophylactic fixation is well established in the management of impending pathological fractures and may be extrapolated to this setting [9-13].

A 26-year-old woman (body mass index 33 kg/m²) presented with chronic left posterior hip pain exacerbated by activity. Physical examination revealed pain during internal rotation and flexion without neurological deficit.

Radiographs and a computed tomography scan demonstrated a well-defined posterior femoral neck osteochondroma measuring approximately 13.5 × 28.5 mm (Figs. 1-6). Bone scintigraphy showed moderate hyperfixation. Magnetic resonance imaging confirmed the benign appearance of the lesion without features of malignant transformation (Figs. 1-6) ^[6].

Surgical technique: 

The patient was positioned in lateral decubitus. A posterior approach allowed direct visualization of the lesion. Complete resection required the removal of a cortical window approximately 1 × 3 cm, resulting in significant weakening of the femoral neck. Considering fracture risk described after similar resections (Fig. 7) ^[7,8], prophylactic dynamic hip screw (DHS) fixation was performed using a 105 mm lag screw and side plate (Figs. 8 & 9) [9-13].

Outcome and follow-up: 

Post-operative recovery was uneventful. Progressive weight-bearing was authorised. At 10 months, the patient was pain-free with restored hip mobility. Radiographs demonstrated stable fixation and progressive cortical remodelling, without complications (Figs. 8 & 9) [9-13].

Femoral neck osteochondromas are rare but may cause significant symptoms due to mechanical impingement [2-5]. Posterior localisations are particularly uncommon. Although malignant transformation is exceptional in solitary lesions, imaging assessment is mandatory (Fig. 1-6) ^[1,6]. Post-operative femoral neck fractures after excision of benign lesions have been reported, highlighting the biomechanical impact of cortical defects ^[7,8]. Prophylactic fixation follows principles used for impending pathological fractures and aims to prevent catastrophic complications [9-13]. In this case, DHS fixation provided immediate stability and allowed early mobilisation with an excellent clinical outcome (Figs. 8 & 9).

Posterior femoral neck osteochondroma is an uncommon cause of hip pain in adults. When surgical excision results in significant cortical weakening, prophylactic DHS fixation may represent a safe strategy to reduce fracture risk (Figs 8 & 9).

Surgical excision of femoral neck osteochondromas can significantly weaken the femoral neck, and in selected cases, prophylactic fixation should be considered to prevent post-operative fracture.