When a brace is enough and when surgery is neededStrong evidence
Health New Zealand and US orthopaedic surgeons agree: a stable break, with the knee able to straighten and lift, is usually treated in a splint, cast or brace holding the knee straight; a displaced break, or a knee that can't straighten, usually needs an operation. Two-part breaks across the middle are usually fixed with wires or screws (a tension band); small fragments at one end may be removed and the tendon reattached; removing the whole kneecap is rare.
A Cochrane review found 11 small trials (564 adults, all at high risk of bias), every one comparing one operation with another, with very low-quality evidence. No trial has compared surgery with a brace, so the choice rests on the break and the person. An older series is reassuring for stable breaks: of 40 treated without surgery, 80% were pain-free and 90% had full movement about 2.5 years later. In Germany, the share of kneecap fractures treated with surgery rose from about half in 2006 to three-quarters in 2020.
Sources 2, 1, 9, 10, 4
Older people with displaced breaks: a judgement callMixed evidence
In 18 people with breaks at least 1 cm apart, 12 of them limited by other illnesses, who walked and bent the knee as pain allowed without surgery, no one had severe pain and 3 had significant limits at 2 years, though the author noted that surgery can do better. In 99 people aged 65 and over, fixation brought more complications than in younger people: 2% infection, 4% of breaks not joining and 11% further operations, and less straightening at 6 months. These are small, old or single-centre studies, so the choice is one to talk through with your surgeon.
Sources 11, 12
The first weeks: NHS practiceStrong evidence
As your fracture clinic allows. Without surgery, NHS fracture clinics fit a splint that keeps the knee straight, often a 'cricket pad' splint with the kneecap in its central hole. You wear it under or over clothes, taking it off only to wash or use a cold pack, with the knee kept straight. You may put weight through the leg as comfort allows, with or without crutches, and a fracture clinic review at about 2 weeks decides how long the splint stays on. The first exercises, 3 times a day with or without the splint, are pointing the foot up and down 10 times and tightening the thigh to push the knee straighter, held for 10 seconds, 7 to 10 times. US surgeons note that some breaks allow no weight for 6 to 8 weeks.
After surgery, US orthopaedic surgeons expect full weight in a splint or brace locked straight, with the knee kept straight for 2 to 4 weeks; Health New Zealand describes a brace for 4 to 6 weeks and no driving while you wear it; and one NHS trust's hinged brace stays on, day and night, until the team removes it, between 6 weeks and 3 months after surgery. Hospitals differ, so your own plan comes first.
Sources 13, 6, 14, 1, 2, 15
Bending again, after surgery: one US protocol and NHS leafletsEmerging evidence
As your fracture clinic allows. We found no trial of a rehabilitation plan after a broken kneecap, and a Cochrane review found no trials of non-surgical treatment. Timings after surgery vary between hospitals, and UK practice may differ from the one US hospital protocol given here.
That protocol, after fixation: no bending for 2 weeks, then 0 to 30 degrees to week 4, 0 to 60 to week 6, 0 to 90 to week 8 and full range after that. The brace stays locked straight for walking for 6 weeks, weight builds from partial to as much as is comfortable over the first 6 weeks, and straight-leg raises start at 2 weeks if the knee doesn't sag. It adds a static bike at 6 weeks, an elliptical trainer at 8, lunges at 12, straight-line jogging at 16 if a functional test is passed, and sport at 5 to 6 months once a return-to-sport test is over 90% of the other leg.
An NHS knee fracture leaflet gives knee bends, knee straightening and thigh exercises, each held for 2 to 3 seconds, 10 times, 3 times a day, in short sessions of 5 to 10 minutes.
Sources 9, 16, 17
Why strength work matters long after the bone healsEmerging evidence
Three small cohorts found lasting weakness after surgery. In 40 people a mean 6.5 years on, the injured thigh was 26% weaker in a static test and 29% to 31% less powerful, 1 in 5 couldn't fully straighten the knee by themselves, and knee scores for sport averaged 45 out of 100. In 30 people in the year after surgery, strength was down 41%, power 47% and endurance 34%, and 80% had front-of-knee pain in daily activities. In 58 people a median 5 years after surgery for complex breaks, the deficit averaged 36%, and bigger deficits went with more pain and worse function.
These studies can't show that more rehabilitation would close the gap, but they show the gap is common, and that it's worth measuring and training.
Sources 18, 19, 20
The metalworkEmerging evidence
Across 14 studies (5,659 people), 29.6% had their metalwork removed because it caused symptoms; the fixation failed in 5.2%, infection followed in 3.1% and the bone failed to join in 1.7%. In smaller cohorts, removal reached 37% to 52%. Health New Zealand says wires are likely to be taken out, after at least 3 months, and painful screws not usually before 12 months, when the bone has fully healed.
Sources 21, 19, 18, 20, 2
Back to daily life, kneeling and sportEmerging evidence
Most people are back to normal activities in 3 to 6 months. An NHS knee fracture leaflet expects normal daily activities in 6 to 12 weeks, apart from high-impact tasks such as running, and no sport for at least 12 weeks; an NHS discharge leaflet for kneecap fractures says no contact sport for 8 to 12 weeks, as your consultant advises. Driving waits until you're out of the brace, walking comfortably and able to do an emergency stop without pain.
Kneeling is often uncomfortable for months. No study gives a kneeling timeline, so ours (on a cushion, once the wound has healed and your team agrees) is a suggestion. After surgery, the US protocol's sport at 5 to 6 months applies to its own patients; your fracture clinic decides yours.
Sources 1, 17, 22, 14, 2, 16
