Clinical: Knee problems, part one.(anterior cruciate ligament)

The essentials

- Hip pathology may frequently present as knee pain.

- If septic arthritis is suspected, urgent referral is essential.

- Anterior knee pain is common but responds to non-surgical measures.

- Some people remain active despite anterior cruciate ligament rupture.

- More than a third of meniscal injuries are due to sporting activity.

1. Examination and investigation of the knee

This week's article deals with problems likely to be encountered in the younger patient.

When presented with a knee problem, simple observation of the knee is helpful. Study the patient's gait, and then look at the knee for swelling and synovial thickening. Note any scars, and the position of the patella.

There may be deformity, such as a flexion deformity or genu varus or valgum.

Palpation and movements

Check the four quadrants of the patella, and test for patellar apprehension.

Examine the patellar tendon, the joint line, the femoral condyles, and the collateral ligament insertions. Check to see if there is an effusion.

Test the range of flexion and extension, both active and passive. The ability to squat and perform straight leg raising should be assessed.

Observe the tracking of the patella during movement of the joint. Hip pathology may frequently present with knee pain. In women of childbearing age, knee pain can be caused by intra-pelvic pathology.

Specific tests

Lachman's test is an anterior draw sign, carried out at 20 deg of flexion, to detect anterior cruciate ligament injury. Also check for pivot shift and the effects of varus and valgus stress. McMurray's test is performed to detect meniscal injury.

The patient lies supine while the examiner rotates the foot fully outward as the knee is slowly extended. A painful click suggests a tear of the medial meniscus.

Investigations

Screening blood tests will rarely show any abnormality in patients with traumatic pathology, but a raised ESR, abnormal RA latex and autoantibodies may help distinguish the inflammatory arthropathies from other causes of pain and swelling. Urate levels may be raised in gout.

Anterior-posterior and lateral knee X-rays with weight-bearing views should be done. In anterior knee pain, consider skyline …