The rectus femoris origin: a vulnerable site in sports injuries

In athletes it is very common for problems at the origin of the rectus femoris to present as weakness while running or kicking the ball, but taking a careful history usually brings out an injury, that is, an acute episode or mild pain during similar activities; these are seen most often in adolescents, in whom there is a history of an acute injury.
Clinically there is local tenderness on palpation over the anterior rim of the acetabulum or the anterior inferior iliac spine. Weakness is found on resisted flexion of the hip with the knee extended and the patient supine, together with accompanying pain. Stretching of the quadriceps is reduced and painful, and the modified Thomas test is positive. These patients may also have accompanying atypical abnormal signs on clinical examination, which are usually not diagnostic.
Radiographs usually show an avulsion of the anterior inferior iliac spine, or even myositis ossificans in this area. Diagnostic ultrasound may show a myositis, a tear and possibly the avulsion of the anterior inferior iliac spine.
These injuries are usually related to kicking, but they can also occur while running, particularly in the first 100 metres and more often in adolescents. Similar injuries have been observed in baseball players as they fall to the ground and the area strikes it. In general these problems are more common than was previously recognised, and persistent pain in the hip can often be caused by weakness of the rectus femoris. Adolescents with an avulsion of the spine or with enthesitis may need several weeks before the symptoms disappear. Myositis is more common in adults.
In treatment, the simplest and commonest measure is rest, ice therapy and elevation of the limb, and the patient may need crutches for the first few days. This condition is generally managed with the conservative measures of physiotherapy and exercise therapy, but it is as well to tell the athlete that recovery often takes time, and that the best way of judging recovery is to measure the weakness rather than to assess the pain, which usually disappears in the final stages of rehabilitation.