Recurrent kneecap dislocations can limit sport and daily activity. Treatment depends on ligament injury, knee anatomy and alignment.
Why the patella dislocates
The kneecap is guided by the groove at the end of the femur, the medial patellofemoral ligament (MPFL), supporting muscles and lower-extremity alignment. Injury to the MPFL is common after a lateral patellar dislocation. Recurrent instability may be influenced by trochlear dysplasia, patella alta, increased tibial tubercle–trochlear groove (TT–TG) distance, rotation or limb alignment. Cartilage or osteochondral injury can occur with dislocations.
How instability is evaluated
The workup includes injury history, assessment of apprehension and tracking, ligament testing, and imaging. X-rays and MRI can help evaluate cartilage, loose fragments, MPFL injury and trochlear shape. Selected patients benefit from measurements of patellar height, tibial tubercle position and overall limb alignment with additional imaging.
Nonoperative management
Many first-time dislocations without a displaced osteochondral fragment can be managed with rehabilitation, swelling control, gradual motion, quadriceps and hip strengthening, and return-to-activity progression. Treatment depends on the mechanism, recurrence risk, associated injury and goals.
MPFL reconstruction
The MPFL is the primary soft-tissue restraint to lateral translation of the kneecap in early flexion. In selected patients with recurrent instability, reconstruction with a tendon graft can restore this restraint. The appropriate graft, fixation and tensioning technique are individualized; overtightening and malposition can cause pain or abnormal joint loading.
When a tibial tubercle osteotomy (TTO) may help
When maltracking, patella alta or an abnormal tibial tubercle position contributes to instability, an MPFL reconstruction alone may not address the underlying mechanics. A TTO repositions the bony attachment of the patellar tendon to adjust tracking or patellar height and can be combined with ligament reconstruction in carefully selected cases. Not everyone with recurrent dislocations requires a TTO; measurements, skeletal maturity, cartilage health and surgical risks guide the decision.
Cartilage injury and more complex anatomy
Dislocations can injure the joint surface. A displaced fragment, focal cartilage defect or substantial trochlear abnormality can change surgical planning. See knee cartilage restoration for discussion of MACI and osteochondral allograft options. Complex realignment or trochlear procedures may sometimes be considered in highly selected circumstances.
Recovery after TTO and MPFL reconstruction
The following is Dr. Haber’s usual recovery framework. An isolated ligament reconstruction, a combined TTO and MPFL reconstruction, or additional cartilage work may require different precautions.
- First 6 weeks: use crutches and put only the amount of weight on the leg allowed by your protocol. Focus on prescribed knee motion and activating the quadriceps—the muscles at the front of the thigh—while the repair or bone work heals.
- Brace for 6–8 weeks: a hinged knee brace protects the knee during early recovery. Follow your protocol for settings and when to wear it.
- After 6 weeks: work toward a normal walking pattern, full knee motion and control of the thigh muscles, as cleared. Gradually increase activity and muscular endurance.
- Around 3 months: strengthening. Begin strength training when cleared, usually around 3 months depending on healing and any additional procedures. Continue to follow the milestones in your protocol before advancing activity or returning to sports.