• Tendinitis of the:

• Obturator hernia.

Tendinitis of the psoas

Tendinitis of the psoas is rare. It may result from an acute hyperextension of the hip or from an overuse injury.^2–6 Iliopsoas impingement is also an uncommon cause of pain after total hip replacement.⁷ The lesion is always located in the femoral triangle and thus accessible to the palpating finger. It can be identified just below the inguinal ligament between the pulsating femoral artery medially and the sartorius muscle laterally.

Tendinitis of the rectus femoris

Resisted flexion is painful, especially if the test is executed with an extended knee (active straight leg raising). Resisted extension of the knee in prone lying position is also painful. The lesion is discussed in ‘Pain on resisted extension of the knee’ (see Ch. 54).

Lesions of the sartorius

Lesions of the sartorius muscle are rare and typically occur in soccer players. Resisted flexion of the hip is painful, especially if some external rotation with a flexed knee is added to the movement. Palpation reveals the localization of the lesion, which is either at the tenoperiosteal insertion or 1 or 2 cm more distal in the tendon. Treatment consists either of deep transverse friction or, if the lesion is tenoperiosteal, of one or two infiltrations with triamcinolone.

In young athletes (aged 15–18) who are skeletally immature, an avulsion fracture of the anterior superior spine of the ilium is more common than a muscle strain or tendinitis (see ‘Pain and weakness’).¹⁰

Obturator hernia

This lesion is principally found in thin, elderly women, often with a history of recent weight loss, obstipation or chronic respiratory disease. The patient complains of numbness or pins and needles, which may eventually culminate in intense pain at the anterior and medial side of the thigh down to the knee. These symptoms result from compression of the obturator nerve at the obturator foramen by a prolapsed fold of peritoneum. Absence of the adductor reflex test is a sign of involvement of motor conduction of the same nerve.¹¹ Pain on resisted hip flexion is explained by pressure exerted by the psoas on the hernia. The differential diagnosis can be made when resisted flexion becomes negative after the patient has been in the Trendelenburg position for upwards of 2 minutes; the effect of gravity is to reduce the prolapse, which is no longer painfully squeezed during active contraction of the psoas.

Avulsion fracture of the anterior superior iliac spine

Avulsion fractures occur more commonly in skeletally immature athletes than in adults because young patients’ tendons are stronger than their cartilaginous growth centres. The same stress that causes a sartorius tendinitis in an adult can cause an avulsion fracture of the anterior superior iliac spine in an adolescent. The fracture does not become widely displaced because of the surrounding thick periosteum.

The lesion is well known in young sprinters, soccer players and jumpers.¹² While running, the subject feels a sudden painful click in the groin and upper part of the thigh. From that moment further activity is impossible and the athlete leaves the track with a limp; even walking is painful.^13,14 On examination, resisted flexion and resisted lateral rotation of the hip and resisted flexion of the knee are all painful. Palpation reveals ecchymosis and palpable tenderness at the anterior superior iliac spine where the sartorius muscle is attached. Radiography shows slight separation of the iliac spine. Spontaneous recovery is the rule and takes 2–3 weeks. During this period, however, total bed rest is not necessary. Movement should be permitted to the limits of pain but return to sports activity should be allowed only from the time that clinical examination becomes fully negative.

Avulsion fracture at the apophysis of the lesser trochanter

This may be seen in schoolboys and young athletes. There is no history of sudden onset because the lesion appears to be caused by overuse.¹⁵ The complaint is of groin pain during walking. Clinical examination shows a normal range of passive movement but resisted flexion is weak and provokes pain. This should be reason enough to obtain a radiograph, which shows separation at the lesser trochanter. In most instances 2 or 3 weeks’ bed rest in a half-sitting position will be enough for recovery to take place. Once the patient can walk without pain, standing is allowed.

It is important to remember that avulsion fractures of the lesser trochanter in adults are almost always the result of metastatic bone disease.¹⁶

Abdominal neoplasm

Infiltration of an abdominal neoplasm into the psoas muscle, although rare, is another cause of considerable weakness of hip flexion and pain in the iliac fossa.

Metastasis in the upper femur

Weakness and pain in the thigh will be accompanied by marked articular signs in the hip joint and probably a ‘buttock sign’ (see p. 637).

Lumbar root palsy

Painless weakness is a major sign in the rare condition of a second lumbar root palsy in a second lumbar disc protrusion. In a third lumbar root palsy, it is less obvious and is also accompanied by weakness of the quadriceps.

Psychoneurosis

Weakness of hip flexion is also a common finding in psychoneurotic patients complaining of pain in the lower back or thigh. The diagnosis can only be made if this sign is accompanied by other inconsistencies in the history and clinical examination (see online chapter Psychogenic pain).

Serious non-specific disorder

Because discoradicular conflicts at the second lumbar level almost never occur, painless weakness of hip flexion should always arouse suspicion of a serious non-specific disorder (see p. 534), such as inflammatory disease or neoplasm.

Inflamed gluteal bursa

An inflamed gluteal bursa is a much more frequent cause of pain on resisted extension, especially if one or more passive movements also elicit the pain (see ‘Gluteal bursitis’, p. 646).

Buttock claudication

Claudication is the symptomatic expression of peripheral artery disease in the leg. It is confined as pain (aching, heaviness, cramping or burning) that is produced with a similar level of walking, disappears after several minutes of standing and occurs at the same distance once walking has resumed.¹⁷ Classically, it appears in the calf and/or thigh, but sometimes is confined to the buttock region only and is then caused by a proximal arterial stenosis (bifurcation of the aorta, common iliac, internal iliac and gluteal arteries).¹⁸ The essential history is that of a buttock pain that forces the patient to stop walking, improves in a minute or two and reappears when the patient starts walking again. The routine clinical examination is completely negative. An additional test – active extension of the hip in prone-lying position – may reproduce the buttock pain (see p. 625). The usual reduction in femoral pulse may be absent if the stenosis is located on the hypogastric or gluteal artery and there is no substantial damage to the aorta–iliac axis.¹⁹ Arterial stenosis is confirmed by Doppler ultrasound or arteriography (Fig. 48.2).²⁰

Adductor longus

Pain on resisted adduction that is localized to the groin usually points to the adductors. While the adductor longus, adductor magnus, adductor brevis and pectineal muscles are all adductors of the hip, of these the adductor longus is most often injured in sports.^2,21–24

The mechanism of an acute injury is usually that of a sharp cutting movement, which causes a forceful eccentric contraction of the muscle. Acute lesions are common in soccer players and often result from a sudden slip on a muddy field, which stretches or tears the muscle or tendon fibres.²⁵ Alternatively, the lesion starts as an overuse phenomenon, such as repetitive abduction and adduction movements of the leg in the skating stride or in defence movements in basketball. It also occurs in high-jumping athletes and ballet dancers²⁶ and has been described in middle-aged cricket bowlers and ice-hockey players.^27,28 Lastly, it is a well-known lesion (‘rider’s sprain’) in horse sports.

Pain is provoked mainly on resisted adduction but full passive abduction may also hurt because it stretches the injured muscle fibres.²⁹ Imaging procedures are usually unnecessary. However, ultrasound, although operator-dependent, can confirm the diagnosis.³⁰

There are three possible locations of the lesion:

The exact site of the lesion is found on palpation and is more often musculotendinous, a few centimetres below the pubic bone, than tenoperiosteal. Exceptionally, the uppermost part of the muscle belly itself is at fault.