Patella Instability
Patella instability occurs when the kneecap (patella) moves out of its normal position, usually shifting toward the outside of the knee. This can range from mild looseness to a complete dislocation, where the patella pops out of the groove at the front of the thigh bone.
Anatomy
The patella sits within a shallow groove on the end of the femur (thigh bone) called the trochlea. It moves up and down smoothly when the knee bends and straightens. Stability comes from the shape of the groove, the surrounding ligaments, and the quadriceps muscles. When these supports are weak, stretched, or injured, the patella can slip out of place.
Patella Instability
Symptoms
Common symptoms include:
- The kneecap “slipping out” or dislocating
- Pain and swelling at the front of the knee
- A feeling of instability or giving way
- Difficulty straightening the knee or walking normally after a dislocation
- Recurrent episodes of the knee “popping” during activity.
Diagnosis
Your doctor will examine your knee for swelling, tenderness, and patella tracking.
Investigations may include:
- X-rays to assess bone alignment and patella position
- MRI scan to check for ligament tears (especially the medial patellofemoral ligament, or MPFL) and cartilage damage.
Treatment
Treatment depends on whether this is your first episode or recurrent instability:
- Non-surgical treatment includes:
- Rest, ice, and crutches, we try to avoid bracing because it can often be left on for too long and result in stiffness and muscle weakness
- Physiotherapy to strengthen the quadriceps and improve patella tracking
- Taping or bracing during sport for extra support
- Surgical treatment may be recommended for recurrent instability or significant anatomical problems:
- MPFL reconstruction to restore the main stabilising ligament
- Realignment procedures to correct abnormal bone alignment.
Recovery
- Non-surgical treatment usually takes 6–12 weeks with physiotherapy.
- After surgery, most patients wear a brace and gradually increase movement and strength under supervision.
- Return to sport or full activity typically occurs within 3–6 months, depending on the type of surgery and rehabilitation progress.
Possible Complications
- While most people recover well, potential issues can include:
- Recurrent instability or re-dislocation
- Ongoing pain or swelling at the front of the knee
- Stiffness or reduced movement
- Early arthritis from repeated dislocations.
When to Seek Help
See your doctor if you experience:
- A kneecap that “pops out” or feels unstable
- Ongoing pain, swelling, or clicking in the front of the knee
- Difficulty regaining confidence in your knee after an injury.
