What are the management options for patellar subluxation?

Management of Patellar Subluxation

The management of patellar subluxation should begin with conservative treatment including quadriceps strengthening exercises, followed by surgical intervention only if conservative measures fail after 3-6 months of well-managed treatment. 1, 2

Initial Assessment and Imaging

Clinical Evaluation

• Assess for:
  • Limited hip abduction
  • Asymmetric buttock creases
  • Leg length discrepancy
  • Patellofemoral instability (occurs in 1-12% of cases after total knee arthroplasty) 1

Imaging

• Plain radiographs are the first-line imaging modality
  • Include weight-bearing axial radiographs to assess patellofemoral kinematics 1
  • Axial radiographs demonstrate the degree of patellar tilt or subluxation 1
• CT is recommended when more detailed evaluation is needed
  • Most commonly used for measuring axial malrotation of knee components 1
  • Can evaluate patellofemoral anatomy in setting of repetitive subluxation 1
• MRI without IV contrast is appropriate when:
  • Radiographs show small osseous fragment along medial patellar margin
  • Clinical concern for prior or chronic patellar dislocation-relocation exists 1
  • Can assess integrity of medial patellofemoral ligament and retinaculum 1

Conservative Management

Exercise Therapy

1. Knee-targeted exercise therapy

   • Quadriceps strengthening (open and closed chain exercises)
   • Progressive loading of the quadriceps 1
   • Shown to provide short-term pain reduction with high certainty evidence 1

2. Hip-and-knee-targeted exercise therapy

   • Combines hip strengthening with quadriceps exercises
   • Demonstrates better efficacy than knee-targeted exercises alone 1

3. Bracing

   • Knee brace with limited range of motion 3
   • Patella-stabilizing bracing for daily activities 4

Additional Conservative Approaches

• Manual therapy of the lower quadrant 1
• Prefabricated foot orthoses (shown primary efficacy compared to wait-and-see) 1
• RICE protocol (Rest, Ice, Compression, Elevation) for acute symptoms 2
• NSAIDs as first-line medication for pain control 2

Surgical Management

Surgical intervention should be considered when:

1. Symptoms persist despite 3-6 months of well-managed conservative treatment
2. Significant functional limitations impact quality of life
3. Recurrent episodes occur despite appropriate conservative management 2

Surgical Options

• For Q angle <14 degrees: Proximal realignment is sufficient 5
• For Q angle >14 degrees: Distal realignment is necessary in addition 5
• For medial patellar subluxation:
  • Medial retinacular release
  • Lateral retinacular imbrication
  • Repair or reconstruction of lateral retinaculum/lateral patellofemoral ligament 4

Evidence on Surgical vs. Non-surgical Treatment

Current evidence comparing surgical to non-surgical management shows:

• Recurrent dislocation: Surgery may result in 157 fewer recurrences per 1000 patients compared to non-surgical management (95% CI 209 fewer to 87 fewer) 6
• Functional outcomes: Uncertain whether surgery improves patient-rated knee and function scores (mean 5.73 points higher on Kujala scale after surgery; 95% CI 2.91 lower to 14.37 higher) 6
• Adverse events: Surgery may increase risk of complications (335 more adverse events per 1000 patients; 95% CI 75 fewer to 723 more) 6

Return to Activity Criteria

Return to full activity is permitted when the patient demonstrates:

1. Complete resolution of pain during and after activity
2. Full range of motion compared to the uninjured side
3. Strength symmetry >90% compared to the uninjured side
4. Successful completion of sport-specific functional tests 2

Common Pitfalls and Caveats

• Excessive combined internal rotation of tibial and femoral components after total knee arthroplasty is directly proportional to the severity of patellofemoral complications 1
• Medial patellar subluxation is often overlooked and requires high index of suspicion 7
• Patellar fractures occur in up to 5.2% of patients after total knee arthroplasty, usually within the first few postoperative years 1
• Many patellar complications after total knee arthroplasty are asymptomatic, highlighting the importance of radiography 1

The evidence for both surgical and non-surgical management of patellar subluxation is of very low certainty, and treatment decisions should prioritize conservative approaches first, with surgery reserved for cases that fail to respond to well-implemented non-operative management.