Surgical Treatment for Chronic Patellar Dislocation
For chronic patellar dislocation, medial patellofemoral ligament (MPFL) reconstruction is the primary surgical intervention and should be performed, particularly in patients without severe anatomic high-risk factors. 1
Primary Surgical Approach
MPFL reconstruction using an anatomic mini-open technique with graft tissue stronger than the native ligament is the standard surgical treatment for chronic lateral patellar instability. 1 This approach has demonstrated superior effectiveness compared to non-surgical management, with isolated MPFL reconstruction reducing subjective persistent patellar instability from 53.6% to 16.7% at 3-year follow-up (odds ratio 5.8) in patients without underlying anatomic risk factors. 2
Key Technical Considerations
- Anatomic femoral positioning of the graft is critical for successful outcomes, as improper placement significantly compromises stability. 1
- Appropriate graft tensioning must be achieved during reconstruction to prevent both under-correction and over-constraint of the patellofemoral joint. 1
- Allograft tissue is an acceptable option for MPFL reconstruction, particularly when combined with other procedures. 3
When to Add Adjunctive Procedures
MPFL reconstruction alone is insufficient when specific anatomic risk factors are present. You must address the following conditions with additional procedures: 1
Trochlear Dysplasia
- Severe trochlear dysplasia (Dejour type D) requires consideration of trochleoplasty in addition to MPFL reconstruction. 1, 2
Malalignment Issues
- Tibial tuberosity-trochlear groove (TT-TG) distance >20 mm necessitates tibial tubercle osteotomy for medialization. 1, 2
- Realignment osteotomy serves as an adjunctive procedure to MPFL reconstruction rather than a standalone treatment. 1
Patella Alta
- Elevated patellar height requires tibial tubercle distalization to restore normal patellofemoral engagement. 1
Special Clinical Scenarios
Chronic Dislocation with Severe Osteoarthritis
When chronic patellar dislocation coexists with severe knee osteoarthritis, perform combined total knee arthroplasty with MPFL reconstruction and patellar resurfacing. 3 This rare scenario requires simultaneous addressing of both the degenerative joint disease and the extensor mechanism pathology.
Long-Standing Fixed Lateral Dislocation
For chronic fixed lateral patellar dislocation (>20 years duration), extensive lateral release combined with MPFL reconstruction is necessary to restore patellar tracking. 4 The lateral release addresses contracted lateral structures that prevent medial translation of the patella.
Post-Total Knee Arthroplasty Dislocation
Chronic patellar dislocation after TKA requires revision surgery with soft tissue rebalancing, which may include novel techniques such as vastus lateralis repositioning to convert lateral forces into medial stabilizers. 5
Important Caveats
Avoid isolated lateral release as a standalone procedure for chronic patellar dislocation, as it does not address the primary pathology of medial restraint insufficiency. 4
Do not perform isolated non-anatomic procedures (such as tibial tubercle osteotomy alone) as first-line treatment, since anatomic MPFL reconstruction demonstrates superior outcomes in preventing recurrent dislocation. 1, 6
The evidence regarding tibial tubercle osteotomy for isolated patellofemoral pathology remains inconclusive with expert opinion only (Level V evidence), making it inappropriate as a standalone procedure. 7
Surgical Timing and Patient Selection
Surgical intervention is indicated after recurrent dislocation episodes (at least two documented dislocations) or after failed non-surgical management lasting 6 months with persistent subluxation symptoms. 1, 8
For first-time dislocations without osteochondral fractures, initial non-surgical treatment with physical therapy starting within the first month is appropriate, with return to sport at 2-4 months using a brace. 8 However, acute MPFL reconstruction may be considered for first-time dislocation when multiple high-risk anatomic factors are present, as this prevents the high recurrence rate (up to 40%) associated with conservative management. 9, 6
Outcomes and Expectations
While MPFL reconstruction significantly reduces recurrent dislocation risk, restoration to previous elite athletic performance levels remains unpredictable, and competitive athletes may not return to their pre-injury level of competition. 6
The procedure carries surgical risks including infection, anesthetic complications, and potential for adverse events, though specific complication rates vary by technique and adjunctive procedures performed. 9