How is patella baja treated?

Treatment of Patella Baja

Surgical intervention is the primary treatment for symptomatic patella baja, with tibial tubercle proximalization, patellar tendon lengthening, or patellar tendon reconstruction being the most effective approaches for improving mobility and reducing pain. 1

Diagnosis and Assessment

Patella baja is characterized by a loss of patellar height, resulting in a patella that sits abnormally low in relation to the femoral trochlea. This condition can be:

• Congenital: Present since early age
• Acquired: Develops secondary to trauma or surgery
• Pseudo-patella baja: Joint line elevation with normal patellar position relative to femoral trochlea 2

Diagnostic Imaging

• Plain radiographs: First-line imaging, including weight-bearing axial views to assess patellofemoral kinematics 3, 4
• Measurement methods:
  • Insall-Salvati ratio (normal >0.8)
  • Modified Insall-Salvati ratio
  • Blackburne-Peel ratio (normal >0.54)
  • Caton-Deschamps ratio
  • Blumensaat's line 2

Clinical Presentation

• Limited knee range of motion
• Anterior knee pain
• Significant weakness with active knee extension
• Extensor lag
• Decreased functional capacity 1

Causes of Patella Baja

1. Post-surgical complications:

   • Total knee arthroplasty (TKA)
   • Anterior cruciate ligament reconstruction (especially bone-patellar tendon-bone grafts)
   • High tibial osteotomies
   • Tibial tubercle osteotomies 1

2. Pathophysiological mechanisms:

   • Quadriceps dysfunction
   • Immobilization
   • Inflammation leading to infrapatellar scarring and adhesions
   • Patellar tendon shortening 1

3. Risk factors after revision TKA:

   • Infection (increases risk of true patella baja)
   • Instability (increases risk of pseudo-patella baja) 5

Conservative Management

Conservative management has limited effectiveness for established patella baja but may help with symptom management:

• Exercise therapy: Knee-targeted exercises focusing on quadriceps strengthening 3
• Hip-and-knee-targeted exercise therapy: Combines hip strengthening with quadriceps exercises 4
• Manual therapy of the lower quadrant 4
• Pain management: NSAIDs as first-line treatment for pain control 4

Surgical Treatment Options

Surgical intervention is indicated for symptomatic patella baja that fails to respond to conservative measures. Options include:

1. Tibial tubercle proximalization:

   • Involves osteotomy and proximal transfer of the tibial tubercle
   • Particularly useful in cases of chronic quadriceps tendon rupture 6

2. Patellar tendon lengthening techniques:

   • Modified Z-plasty: Creates four reins to enable multifold overlapping of tendon tissue
     • Improves CD ratio from median 0.53 to 1.03
     • Improves knee flexion from median 108° to 143°
     • Reduces pain (VAS) from 8.5 to 1 7
   • End-to-end patellar tendon lengthening with hamstring autograft augmentation 1

3. Patellar tendon reconstruction:

   • Using allografts or autografts to augment tendon lengthening or reconstruction 1

4. Corrective measures during TKA revision:

   • Reestablishing the joint line using distal femoral augments
   • Shaving of the anterior portion of the tibial polyethylene
   • Placement of the patellar implant in a cephalad position 2

Outcomes and Complications

• Range of motion: Significantly reduced in patients with patella baja (113.3°) or pseudo-patella baja (110.5°) compared to normal (122.0°) after revision TKA 5
• Complications if untreated:
  • Decreased range of motion
  • Decreased lever arm
  • Extensor lag
  • Impingement of the patella against tibial components
  • Anterior knee pain
  • Increased energy expenditure
  • Risk of patellar or quadriceps tendon rupture 2

Prevention

Prevention is crucial, especially during knee surgeries:

• Avoid excessive soft-tissue release during TKA
• Maintain proper joint line height during primary and revision TKA
• Proper placement of patellar components
• Early mobilization after knee surgery to prevent adhesions 2

Follow-up and Monitoring

• Regular radiographic assessment to monitor patellar height
• Evaluation of range of motion and functional outcomes
• Assessment of pain levels and quality of life 3

Patella baja represents a challenging condition that significantly impacts knee function and patient quality of life. While conservative measures may help with symptoms, surgical intervention is typically required for definitive treatment in symptomatic cases.