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What happens during a dislocation?
The kneecap normally moves in front of the thigh bone as the knee bends and straightens. During dislocation it leaves this position, most often towards the outside. Tissues that help hold it may be injured. Sometimes a fragment of bone or cartilage accompanies the injury.
Kneecap dislocation differs from dislocation of the entire joint between the thigh bone and shin bone. The latter can threaten blood vessels and nerves. With deformity after an accident, do not try to distinguish them yourself: seek urgent help.
Understand the picture
The kneecap and its usual position
Thigh bone
It has an area where the kneecap moves during bending.
Usual position
The kneecap sits at the front of the knee.
Displacement
Moving out of this position needs assessment.
How may the injury appear?
It may happen during a pivot, landing or blow. Pain may be severe, with visible deformity, swelling and inability to move normally. In other cases, the kneecap returns quickly and the deformity is no longer visible at the appointment.
Describe the position you saw, the movement and when swelling appeared. Mention a feeling that “something slipped”. Apprehension during certain movements can persist afterwards. This alone does not reveal which structures were injured.
Chapter sources [2]
What should you do while waiting for medical help?
Keep the knee still in the position found and support it with rolled clothing or cushions without forcing it. Do not try to straighten the leg, walk on the injured limb or push the kneecap back. If reduction is needed, a professional should perform it.
Deformity, very rapid swelling, intense pain, a major wound or a cold or numb foot warrants urgent help. In Luxembourg, call 112 if the situation is an emergency or you cannot travel safely. Do not drive yourself.
Why seek assessment if the kneecap has returned?
Spontaneous return does not check the condition of cartilage, bone or supporting tissues. The doctor examines the knee and, according to the circumstances, circulation and sensation. An X-ray is often needed; MRI may be discussed to clarify some injuries and guide treatment.
Assessment also distinguishes a first episode from repeated instability. Mention previous episodes, even if they were not very painful. Findings, age, possible ongoing growth and activities affect the plan. Simply being told the kneecap is back does not replace this information.
What affects the risk of recurrence?
The shape of joint surfaces, kneecap position, tissue flexibility and previous injuries can contribute. Strength and movement control also matter for activities. These factors cannot be reduced to a lack of willpower or poor posture.
A professional can explain the factors specific to you. Rehabilitation improves abilities but does not change every anatomical feature. A new feeling of the kneecap slipping out or repeated instability needs reassessment even if you have already done exercises.
Chapter sources [1]
Which protection and treatments are possible?
After assessment, a walking aid or knee support may be offered. Weight-bearing, bending and duration instructions depend on the injury and treatment. Instructions while awaiting reduction differ from rehabilitation instructions after medical care.
Surgery may be discussed for major damage, a fragment needing treatment or recurrent instability. It is not automatic after every first episode. Ask about the treatment’s specific aim, alternatives and restrictions. Surgery does not replace preparation of muscles and activities.
What does rehabilitation work on?
At first, it supports recovery of movement, swelling control, muscle activation and suitable walking. Later, it builds strength around the knee and hip and control during tasks. Exercises are chosen according to permitted movements and your tolerance.
Confidence is developed alongside this through gradual situations. Do not push the kneecap sideways yourself to test whether it stays in place. The Exercises page offers general support; after dislocation, a professional should confirm suitable movements and limits.
In everyday life
Distinguish three stages
Before care
Support the knee without trying to put the kneecap back.
After assessment
Respect protection and permitted movements.
During return
Gradually build strength, control and confidence.
How can you manage the first weeks at home?
Organise journeys and stairs around permitted weight-bearing. A handrail, stable chair and prescribed aids can make tasks easier. Follow the doctor’s or pharmacist’s advice for pain treatment. Pain relief does not allow you to remove a protective restriction.
For rest and sleep, ask how to position the leg and whether to wear the support. After any surgery, monitor the wound as instructed. Fever, increasing redness or discharge requires prompt contact with the team rather than waiting for the next appointment.
Chapter sources [2]
When can you return to work, running and sport?
Returning to desk work, physical work and pivoting sport requires different abilities. Plan return according to walking, stairs, strength and actual demands. Driving requires reliable vehicle control without interfering effects from treatment.
Before sport, the team checks movement, stability, strength and the ability to perform expected tasks without a marked response. Partial training may precede full return. A knee may walk well before it is ready for landing or a fast change of direction.
How long does recovery take?
Full recovery may take several months and varies with injury and treatment. Pain decreasing quickly does not mean every tissue has recovered. Intermediate goals make progress more visible and avoid judging everything by a return date.
Persistently limited straightening, lasting swelling, significant catching or another episode of instability needs advice. If exercises do not improve abilities or fear prevents progress, have the plan adjusted. A newly visible displacement of the kneecap remains an injury needing prompt assessment.
Your questions
Can I put the kneecap back with my hands?
No. Keep the knee supported without forcing it and seek medical help. Manipulating it yourself can worsen an injury and does not check the damaged structures.
Chapter sources [2]
Should I seek assessment if everything seems back in place?
Yes. Bone, cartilage or supporting tissue injury may accompany the episode. Examination and any imaging guide protection and follow-up.
Chapter sources [2]
Does a knee support prevent another dislocation?
It may form part of the plan but does not guarantee no recurrence. Its type, settings and wearing duration should be suitable. It does not replace rehabilitation or reassessment of instability.
Chapter sources [1]
Is fear of bending the knee normal?
Apprehension can follow a frightening injury. Discuss it with your professional to build reassuring, permitted steps. It is also necessary to check whether injury, locking or swelling is physically limiting movement.
Chapter sources [2]
Sources and references
- [1] AAOS — Patellar dislocation and instability
- [2] NHS — Dislocated kneecap
- [3] Assurance Maladie — Douleurs du genou : que faire et quand consulter ?
- [4] CGDIS — 112 Luxembourg
Text updated on
Medical review: awaiting Hasib Selimovic.