Alternative names: patellofemoral pain syndrome, cinema knee, theatre-goer’s knee. (Why the last two, I have no idea; it’s linked with athletics.)
What it is: A broad term for anterior knee pain with no specific identified cause, usually due to a muscle imbalance around the knee that leads to maltracking of the patella in the intercondylar groove (most commonly too laterally) with consequent pain and sometimes cartilage damage.
How it presents: Gradual-onset anterior knee pain involving patella and retinaculum.
What the difference is between this and chondromalacia patellae: Chondromalacia patellae is a term for softening of the patellar articular cartilage, which affects a subset of patients with anterior knee pain. Cartilage damage doesn’t necessarily correlate well with symptoms. The presence of chondromalacia patellae does not affect management of anterior knee pain.
Who gets it: Young people, particularly adolescent girls who do athletics. Long-distance runners or hill runners.
Other risk factors: Previous knee dislocation, small kneecap, kneecap which protrudes when the feet pronate, tight muscles, weak quads, foot abnormalities.
Examination: Assess dynamic patellar tracking by having patient perform single leg squat and then stand with hip, knee, and ankle in straight line. Observe gait to look for excessive subtalar pronation. Look for pes cavus or lowered arches, genu varum or valgum, valgus ankles or excessive pronation of feet. Alternatively, leave all this to someone who understands biomechanics well enough to have some clue of how to act on the findings.
Investigations: Not mentioned apart from in the context of biomechanics, so I’m assuming no role for the GP to order imaging.
Treatment: Mainly physio. Also knee taping and footwear advice. If all else fails, surgery is sometimes appropriate (only where there is a clearly defined cause, and only in conjunction with follow-up physio).
Things GP can advise while waiting for physio: Rest, advice, NSAIDs, and quads exercises. The exercise recommended was to lie supine with the affected leg straight and the other leg bent, toes pointing at ceiling, to contract the quads and then SLR of whole leg & hold for five seconds, lower, relax for 5 s and work up to 20 reps.
Prognosis: In one small study in which all patients received intensive exercise programmes, almost three-quarters of the patients had good functional recovery six months down the line, but this percentage didn’t seem to have changed by seven years later. (From the abstract.)
(Notes on Pulse on-line learning module: Professor Fares Haddad, consultant orthopaedic surgeon, and Mr Tony Fayad, registrar)