Introduction

Femoroacetabular impingement (FAI) is a frequent cause of mechanical hip pain, in the last few years a lot of attention has been paid to it. The cause of FAI is the abnormal contact between the femurs against the acetabular rim secondary to intra-articular or extra-articular factors. The abnormalities in the femoral head-neck junction (cam lesion), acetabulum (pincer lesion), or a combination of both are part of the intra-articular causes [1,2]. Whereas, extra-articular causes of hip impingement, including anterior inferior iliac spine (AIIS) impingement, psoas impingement, greater trochanteric–pelvic impingement, and ischio-femoral impingement [3].

Case Report

A 16-year-old male non-agonistic football player presented with a 1-year history of right hip pain exacerbated after simple hip hyperflexion trauma. He rated his pain as a 7 on a 10-point scale (0, no pain; 10, most pain imaginable). The pain was irradiated along the course of the rectus femur muscle. He did not remember direct or indirect trauma to the right hip in the past, nor sports injuries. There was no history of fever, lack of appetite, or weight loss. The past medical history was insignificant; there was no history of antecedent surgery or radiation exposure. The general physical and systemic examinations were within normal limits. Recently he presented with antalgic limps, running and jumping aggravated the pain, as well as sitting for a long period of time. He gave up on sports activities. Objectively he presented pain and hard swelling on palpation over the AIIS. The range of motion (ROM) of the right hip was limited to 85° of flexion, 10° of internal rotation, 40° of external rotation and 30° of hip abduction compared with the contralateral side which had normal ROM values (120°, 30°, 45°, and 45° respectively). The right hip extension was equal to the contralateral hip. Initial standard anteroposterior (AP) and Dunn lateral view were obtained. Radiographs demonstrated an irregular bone formation at the level of the AIIS (Figure 1). The exostosis of AIIS with an anteroinferior course and contiguity with the origin of the anterior rectus muscle was confirmed by computed tomography (CT) scan (Figure 2). The MRI findings showed signal modifications at the level of AIIS without periwound reaction or edema and without influences on the surrounding tissue. The hematological and biochemical tests were within normal limits. The tests performed suggested a benign lesion, most probably an exostosis. Excisional surgery of the exostosis and histological examination were suggested to the young patient.

Figure 1: Standard AP Xray (A) and Dunn lateral view (B).

Figure 2: CT scan view on transverse (A) and sagittal (B,C) reconstructions.

Excision surgery was performed through a 10 cm incision with an anterior, modified Smith-Petersen approach. The tensor fascia was incised, the deep layers were dissected until the lesion was reached. High attention was aimed at not harming the lateral femoral cutaneous nerve and the femoral nerve. The mass was removed using an osteotome, it was of compact consistency and macroscopically the separation between compact and spongy bone was clearly evident. It was sent for histopathological examination. The direct head of the rectus femoris, previously collected, was reinserted at the AIIS base through an 5,5mm PEEK anchor (Figure 3). After surgery we performed standard X-ray (Figure 4). Partial weight-bearing was permitted and was advised to avoid hip hyperextension and maximum rotations. The patient's recovery period of 4 weeks has fully re-integrated him into his daily activities. He returned to sports activities in three months without pain. The histopathologic findings were as follows: cortical cancellous bone fragment with mature cells pattern. The young athlete underwent a clinical and radiological (X-ray) follow-up at one and two years. The situation was the same: he leads a normal life, free from functional limitations and pain. He practices competitive sports at a level comparable to boys of his age. The ROM of the right hip was: 115° of flexion, 20° of internal rotation, 50° of external rotation, and 55° of hip abduction. Values fully comparable to the contralateral hip. Radiographs demonstrated radiographic anatomy of the hemipelvis comparable to postoperative control. No appearance of heterotopic ossification or bone recurrence was present.