Radiographic examination will be of assistance, as in 30 degree flexion a line should pass from the femoral shelf through the inferior pole of the normal patella.

A lateral x-ray of the knee demonstrating patella alta.

The tibial tubercle is palpated; this may be tender in Osgood-Schlatter disease (tibial epiphysitis) or protuberant in a person who has suffered from that condition.

Apophysitis may also occur at the distal pole of the patella (Sindig-Larsen disease). A direct blow may cause fracture of the tubercle.

Rarely, avulsion of the tibial tubercle may occur in young adults, with a resisted intense quadriceps contraction.

The patellar tendon is palpated which will be tender in patella tendonitis (jumper’s knee).

Tenderness is often elicited on the inferior pole of the patella, a site also likely to rupture during a strenuous activity while the knee is bent to a right angle. The radiograph may show localised calcification; patella magna may also be noted.

The prepatellar bursa is palpated. Sponginess of the patella arouses suspicion of prepatellar bursitis. The possibility of infection of the bursa should always be borne in mind, particularly as bursitis is often caused by direct trauma with an associated graze.

The knee joint is checked for full flexion and then for a full range of motion. This test should be performed both actively and passively. The examiner palpates for patellar crepitus.

Pain towards full flexion and inability to reach it is usually due to the presence of an effusion.

Flexion of the swollen joint will cause the posterior joint space to become tense and painful; this may be associated with a ‘baker’s cyst’. Full flexion may also be restricted by popliteal pathology, loose bodies, posterior osteophytes and quadriceps pathology (muscle tear, tumour, haematoma, or myositic ossifications).