Knee Pain

INTRODUCTION

Key facts and checkpoints

• A ruptured anterior cruciate ligament (ACL) is the most commonly missed injury of the knee.

• A rapid onset of painful knee swelling (mins to 1–4 h) after injury indicates blood in the joint—haemarthrosis: the main causes are torn cruciate ligaments, capsular tears with collateral ligament tears, peripheral meniscal tears, fractures and dislocations.

• Swelling over 1–2 days after injury indicates synovial fluid—traumatic synovitis.

• Acute spontaneous inflammation of the knee may be part of a systemic condition such as rheumatoid arthritis, rheumatic fever, gout, pseudogout (chondrocalcinosis), a spondyloarthropathy (psoriasis, ankylosing spondylitis, Reiter syndrome, bowel inflammation) and sarcoidosis.

• Consider Osgood–Schlatter disorder in the prepubertal child (esp. boys 10–14) presenting with knee pain.

• Disorders of the lumbosacral spine (esp. L3–S1 nerve root problems) and of the hip joint (L3 innervation) refer pain to the region of the knee joint.

• Osteoarthritis of the hip often presents as knee pain.

OSGOOD–SCHLATTER DISORDER

Most common at 10–14 yrs; : = 3:1

Management This is conservative as it is a self-limiting condition (6–18 mths: av. 12 mths).

• If acute, use ice packs and analgesics.

• Main approach is to abstain from or modify active sports.

• Avoid steroid injections and POP immobilisation.

• Surgery (rarely) if irritating long-term ossicle.

• Physiotherapy: gentle quadriceps stretching.

CHONDROCALCINOSIS OF KNEE (PSEUDOGOUT)

• Calcium pyrophosphate deposition

• In older people >60

• Can present with hot, red, swollen joint.

• Aspirate knee to search for crystals.

• Treat with NSAIDs or IA steroid injection.

• Colchicine can be used.

MENISCAL TEARS

• Can occur with described injury (abduction or adduction force with twisting usually on a weight-loaded flexed knee)

• Joint line pain ± locking is main symptom

Signs

• Localised tenderness over joint line

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