Patellofemoral cartilage repair

Courtesy: Dr A Gomoll, Ashok Shyam TV, Ortho

Clinical Context

• First-time patellar dislocators traditionally require surgery only when a loose body is present.

• However, many patients present with:

  • Cartilage defects on magnetic resonance imaging.

  • No loose body.

  • Unclear indication for surgery.

Key question:
When should patellofemoral cartilage defects be treated surgically?

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Incidence of Patellofemoral Cartilage Defects

• Patella is the second most common location for cartilage defects after the medial femoral condyle.

• Cartilage defects are extremely common.

• Not every defect is symptomatic.

• Not every anterior knee pain is structural.

Important principle:
Treat the patient, not the MRI.

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Defects That Can Often Be Ignored

1. Small Defects Without Pain

• Patient has instability.

• Small cartilage lesion.

• No mechanical symptoms.

• Management: Address instability; cartilage may not need intervention.

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2. Inferomedial Patellar Facet Defects

• Classic location after patellar dislocation.

• Inferomedial pole injury from impact.

• Rarely heavily loaded during normal motion.

• Often asymptomatic long-term.

• Management:

  • Remove loose body if present.

  • Focus on instability.

  • Cartilage repair often unnecessary.

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3. Very Anterior Lateral Femoral Condyle Defects (Countercoup Injury)

• Occurs during dislocation event.

• Located outside primary weight-bearing zone.

• Does not articulate in functional flexion.

• Management:

  • Debridement if needed.

  • No formal cartilage reconstruction.

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4. Inferolateral Patellar Defects in Maltracking Patients Undergoing Osteotomy

• Tibial tubercle osteotomy unloads the inferior patella.

• If unloading corrects biomechanics, cartilage procedure may not be required.

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Defects That Should Be Treated

1. Acute Osteochondral Fractures

• Young patients.

• Large fragment.

• Intact cartilage surface.

• Treatment:

  • Repair whenever possible.

  • Screws, bioabsorbable darts, or sutures.

  • Better healing in skeletally immature patients.

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2. Cartilage-Only Delamination in Young Patients

• Open growth plates.

• Even without bone attached.

• Evidence suggests reasonable healing potential.

• Prefer repair in young patients.

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3. Large Chronic Defects in Weight-Bearing Zones

• Especially involving:

  • Median ridge of the patella.

  • Central or weight-bearing lateral femoral condyle.

• Often associated with:

  • Recurrent instability.

  • Maltracking.

These may require:

• Cartilage restoration.

• Combined stabilization procedure.

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Age Considerations

Skeletally Immature Patients

• Higher healing potential.

• Favor repair even if cartilage-only fragment.

• Combine with MPFL reconstruction if instability present.

Adults (25–30 years and older)

• Cartilage-only fragments less likely to heal.

• Fragmented or degenerative pieces:

  • Remove.

  • Consider reconstruction based on size and symptoms.

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Repair Techniques

Fixation Options

• Headless compression screws.

• Bioabsorbable darts.

• Suture fixation.

• Open or arthroscopic approaches.

Small studies show:

• Good healing rates in young patients.

• Particularly effective in osteochondral fragments.

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Reconstruction Options

Used when repair is not possible.

Surface-Based Treatments (Bone Intact)

• Autologous chondrocyte implantation.

• Minced autologous cartilage technique.

• Microfracture (limited role in patella).

• Bone marrow–augmented cartilage repair.

Osteochondral Techniques (Bone Compromised)

• Osteochondral autograft.

• Osteochondral allograft.

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Modern Technique: Minced Autologous Cartilage

• Cartilage biopsy harvested.

• Minced into small fragments.

• Mixed with bone marrow aspirate concentrate and fibrin glue.

• Placed into defect.

• More cost-efficient than autologous chondrocyte implantation.

• Increasingly popular option.

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Clinical Case Patterns

Case 1: Multiple Dislocations in Adolescent

• Extensive lateral femoral condyle damage.

• Required:

  • MPFL reconstruction.

  • Autologous chondrocyte implantation.

  • Guided growth procedure for valgus alignment.

Lesson:
Repeated instability leads to progressive cartilage loss.

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Case 2: Weight-Bearing Lateral Femoral Condyle Defect

• Moderate trochlear dysplasia.

• Osteochondral allograft.

• MPFL reconstruction.

• Good integration.

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Decision-Making Algorithm

Ignore:

• Small, non-weight-bearing defects.

• Inferomedial patella defects.

• Very anterior lateral femoral condyle lesions.

• Defects that will be unloaded by osteotomy.

Repair:

• Large osteochondral fragments.

• Young patients with viable cartilage.

• Acute injuries.

Reconstruct:

• Large defects.

• Non-repairable fragments.

• Weight-bearing surface involvement.

• Median ridge involvement.

• Chronic recurrent instability cases.

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Key Principles

• Not every cartilage defect needs surgery.

• Symptoms must correlate with lesion location.

• Young patients deserve aggressive preservation.

• Address instability simultaneously.

• Prevent repeated dislocations to avoid cumulative cartilage damage.

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Final Take-Home Points

• Inferomedial patellar defects: usually ignore.

• Anterior lateral femoral condyle defects: often ignore.

• Large fragments: repair if possible.

• Large chronic defects: reconstruct.

• Combine cartilage surgery with instability correction.

• Do not allow repeated dislocations in young patients.