What is patellofemoral instability?
Patellofemoral instability is a condition where the kneecap dislocates from its bony groove in the front of the knee.
What can cause it?
Dislocations or subluxations can occur for a number of reasons.
- Traumatic – Often the result of an injury. No underlying bony, soft tissue issues
- Bony or soft tissue issues
- Hypermobility/ Increased tissue laxity
What are the symptoms and signs?
- Recurrent dislocations
- Loss of confidence in the knee
- Associated pain at the front of the knee
- Composite dynamic functional assessment often reveals issues with trunk and buttock muscles along with inhibition of quadriceps musculature
- Thigh muscle wasting/ knock knees
- Beighton’s score may be elevated
What investigations may be required?
- Full rotational profile assessment
- Full-length weight-bearing X-rays with skyline patella views
- X-rays with knee in thirty degrees of flexion
- CT scan
- MRI scan
These investigations are necessary to quantify the following key Patellofemoral indices:
- Patella Alta
- Tibial tuberosity and trochlea groove distance
- Trochlear dysplasia
- MPFL integrity
- Chondral surface assessment
Click here for more information on knee dislocation surgery.