Osteochondroma is the most common benign bone tumour. In 85% of patients, it presents with a solitary lesion, and in 15% of patients, it manifests as hereditary multiple exostoses (HME). Approximately 50% of osteochondromas are located around the knee. Resection is indicated only for symptomatic compressive lesions or when the adjacent joints are in jeopardy. Malignant transformation and cosmetic factors are infrequent indications for surgical intervention ^[1]. The overall recurrence rate is about 2%. Interestingly, spontaneous resolution of solitary osteochondromas has been reported ^[2]. Solitary femoral neck osteochondroma (SFNO) is rare; it requires special attention and careful surgical planning owing to its proximity to neurovascular structures and vulnerable femoral head blood supply and the variety of operative corridors for tumour resection in this area. SFNO may present with pain, neuropathy, limp, limited hip range of motion, and ischiofemoral impingement. Impingement can be exaggerated by the presence of thoracolumbar kyphosis and secondary hip extension ^[3]. Femoral head osteochondroma likely represents another neoplastic process, namely, Trevor’s disease, which is approached differently ^[4]. Juxta-articular, extraskeletal osteochondroma has been reported to float in muscles surrounding the femoral neck ^[5,6]. In this report, we describe a patient with SFNO who presented with an intertrochanteric fracture. We also aimed to review the literature for appropriate treatment methods that may improve decision-making.

A 23-year-old male was brought to the emergency department of our institution after a head-on motor vehicle collision in February 2021. His Glasgow Coma Scale score was 15, with no evidence of haemodynamic instability. His chief complaint was right hip pain and inability to walk. He had been an unbelted front-seat passenger and had been forced under the dashboard, where he felt a snap in his right hip. There were no other injuries. The patient was completely asymptomatic before this presentation and had no medical illness. He underwent surgery for a right proximal humerus fracture that resulted from a high-energy fall 6 years earlier and which had healed uneventfully. An anteroposterior pelvic radiograph at that time was performed as a part of the Advanced Trauma Life Support guidelines, and an asymptomatic right proximal femur lesion, which the patient was not aware of, was noted (Fig. 1).

Figure 1: Pelvic radiograph showing right proximal femur lesion 6 years prior to the current presentation.

On examination, right hip tenderness was detected, and minimal hip range of motion was painful. The motor, sensory, and vascular exams were normal. New radiographs revealed a right hip intertrochanteric fracture in addition to the pre-existing mass (Fig. 2).

Figure 2: Pelvic radiograph obtained in the emergency department revealing right hip intertrochanteric fracture and osteochondroma.

A computed tomography (CT) scan established the diagnosis of SFNO, which was continuous with the displaced fracture (Fig. 3).

Figure 3: Coronal (left image) and axial (right image) computed tomography views outlining the fracture.

The tumour arose from the femoral neck just proximal to the lesser trochanter, projecting posteromedially. We believe that the priority in this case was to address the fracture and resect as much of the asymptomatic lesion as possible, mainly for histologic diagnosis and better healing. This was achieved in the operating room under general anaesthesia after admission and preparation. To maintain simplicity and ease, we chose the lateral approach in the supine position. The reduction and fixation were aided by a fracture table and a short dual-screw cephalomedullary nail. The tumour was removed in a piecemeal fashion under fluoroscopy. Adequacy of resection was based on clinical and radiographic assessment of the ischiofemoral space. Histopathologic examination confirmed the diagnosis of osteochondroma. The patient was discharged on post-operative day 2 in good condition. He was allowed partial weight bearing for 6 weeks, followed by full weight bearing. At 3 years and 8 months of follow-up (October 2024), the patient reported mild activity-related right lateral thigh pain. However, he demonstrated a full range of motion, had a healed fracture on radiographs, and showed no evidence of recurrence (Fig. 4). We believe that the treatment goals were achieved.

Figure 4: Anteroposterior and lateral follow-up radiographs,

The lateral approach is probably less tedious because it allows for convenient simultaneous reduction and fixation of the fracture with easy intraoperative imaging. However, it does not allow for thorough medial resection. A cephalomedullary nail provides a reliable form of stabilisation but may cause irritation to the iliotibial band. It is probably advantageous to use intramedullary fixation compared to extramedullary plates, especially when the femoral calcar area and the lateral wall are compromised. The tumour in this patient originated from the medial femoral neck. In a study of 100 hips with HME, 79% of proximal femur osteochondromas were found medially ^[7]. Conservative treatment has been described in patients with minimal symptomatology ^[8]. After the patient developed complete post-operative sciatic nerve palsy, Jeon et al. warned against approaching a posteriorly protruding tumour through the anterior approach; the patient underwent immediate post-operative exploration, and the nerve recovered 6 months postoperatively ^[9]. Ghoti et al. excised a posterior femoral neck osteochondroma through a posterior approach in a patient with HME, which resulted in the resolution of symptoms and no recurrence on follow-up after 3 years ^[10]. Sorel et al. have used surgical hip dislocation to treat femoral neck osteochondroma in 20 hips of HME patients; there was significant improvement in pain and range of motion at the expense of four notable complications: One fibrous nonunion of the trochanteric osteotomy, another osteotomy fixation failure, a pertrochanteric fracture, and avascular necrosis ^[11]. Small intracapsular lesions are likely amenable to arthroscopic resection. Hip arthroscopy has been used in patients with HME and other hip afflictions such as synovial chondromatosis ^[12]. Mansor et al. resected a metachondromatosis femoral neck lesion in a child arthroscopically ^[13]. Alter et al. described arthroscopic hip extended capsulotomy for a 2.2 cm osteochondroma, which was distal to the capsular attachment ^[14]. Sun et al. used intraoperative CT navigation in 13 patients with femoral neck osteochondroma, 8 of whom were solitary; 9 patients had posterior exposure, whereas four hips were operated on through the anterior approach ^[15]. We are not aware of any published case of SFNO that presented with a hip fracture. Schubert et al. described posteromedial femoral neck osteochondroma in a 53-year-old woman who was known to have HME. She presented initially with symptoms of ischiofemoral impingement, and 3 months later she was referred with a displaced intracapsular hip fracture that was treated with a total hip replacement ^[16]. In the series reported by Ramos-Pascua et al., a 66-year-old male patient was noted to have an iatrogenic basicervical femoral neck fracture during excision through an anterior approach of a medial SFNO that was treated by a short cephalomedullary nail ^[17]. Bottner et al. reported an intraoperative femoral neck fracture during osteochondroma removal in a 44-year-old patient whose osteosynthesis failed and who required total hip arthroplasty ^[18]. The risk of recurrence after resection of SFNO is low, as there is no single case of recurrence in the relevant papers as summarised in Table 1.

Table 1: Published reports describing solitary femoral neck osteochondroma treatment

The treatment of osteochondroma is based on the presenting symptoms, and the surgical approach is best dictated by the location of the lesion within the femoral neck. Associated actual or impending fractures are fixed through standard techniques and implants.

A lateral approach to surgical fixation and tumour removal can be used to treat extracapsular hip fractures caused by posteromedial SFNO.