- Can occur with a significant injury (e.g. clash of knees during sport) or with much less energy (e.g getting up from a sitting position) in those with pre-existing risk factors (hypermobility, shallow trochlea, malalignment).
- May reduce spontaneously or may require to be reduced manually
- The risk of recurrence after first-time dislocation varies according to clinical studies and is probably around 20%. The risk is likely influenced by the presence of underlying risk factors and patient age.
Patellar Instability
General advice
Symptoms and signs
- Knee pain
- Stiffness and swelling
- Cracking or popping sounds in the knee on knee flexion activities or stairs
- Feeling like the kneecap is catching or subluxing
Initial management
- A and E attendance appropriate for unreduced patellar dislocation.
- Analgesia as appropriate/ NSAIDs may also help if no contraindications.
- For all first-time dislocated patella - X-ray to look for osteochondral fracture.
- Those without osteochondral fracture refer for MSK Physiotherapy.
Who to refer
- Those with an osteochondral fracture - URGENT referral to knee clinic.
- Recurrent dislocation with haemarthrosis - Patellar stabilisation surgery (typically MPFL reconstruction) may be discussed with the patient and further investigations arranged (CT or MRI)
Who not to refer
Patients should have completed a 6 month course of PSK Physiotherapy prior to referral unless there is indication for urgent referral.
How to refer
- SCI Gateway/Orthopaedics/Knee
- If the patient is under the care of NHS Physiotherapy, investigations and onward referral to knee service, if appropriate, will be organised by Physiotherapy service without the need for further GP intervention.
Information to include when referring:
- Duration, mechanism of injury, and any cause of symptoms
- Indicate site/ spread of pain and if pain constant or intermittent, and/or waking at night
- Indicate active and passive ROM
- Include treatment to date
- XR results