What is the recommended management for an 18‑year‑old athlete with a reduced acute traumatic patellar dislocation, a large medial patellar cartilage defect, intra‑articular loose bodies, a disrupted medial patellofemoral ligament (MPFL), and a significant knee effusion?

Surgical Management for Acute Patellar Dislocation with Structural Damage

This 18-year-old athlete requires urgent arthroscopic surgery to remove loose bodies and address the large cartilage defect, followed by MPFL reconstruction, given the combination of intra-articular pathology and complete ligamentous disruption. 1, 2

Immediate Surgical Indications

Your patient meets multiple criteria that mandate operative intervention rather than conservative management:

• Large cartilage defect on the medial patellar facet represents significant osteochondral injury requiring surgical treatment 1, 2
• Intra-articular loose bodies must be removed arthroscopically to prevent further cartilage damage and mechanical symptoms 1, 2
• Complete MPFL disruption with associated structural damage warrants ligamentous reconstruction rather than repair 2
• Significant effusion in the setting of these injuries indicates substantial intra-articular pathology 3

Surgical Algorithm

Stage 1: Arthroscopic Assessment and Cartilage Management

• Diagnostic arthroscopy should be performed first to fully evaluate the extent of chondral injury, as MRI has only 43% sensitivity for detecting osteochondral lesions in patellar instability 4
• Remove all loose bodies identified during arthroscopy, noting that MRI sensitivity for loose bodies is only 52% 4
• Address the cartilage defect based on size and depth:
  • Chondroplasty for unstable cartilage flaps 4
  • Consider microfracture, autologous chondrocyte implantation, or osteochondral autograft transfer depending on defect size and location 3, 2
• Document all Outerbridge grading of chondral lesions throughout the patellofemoral joint 4

Stage 2: MPFL Reconstruction

• MPFL reconstruction is superior to repair in this setting, as repair has limitations related to injury location and provides less reliable stabilization 2
• The MPFL provides 50-60% of restraining force against lateral patellar displacement and is injured in 94-100% of first-time dislocations 2
• Reconstruction should be performed during the same surgical session after addressing intra-articular pathology 2

Critical Imaging Limitations

Be aware that your MRI significantly underestimates the true extent of injury:

• MRI has only 43% sensitivity for osteochondral defects and 52% sensitivity for loose bodies in patellar instability 4
• Plain radiographs are even worse, with only 8% sensitivity for osteochondral lesions and 23% for loose bodies 4
• Expect to find additional chondral injuries during arthroscopy that were not visible on preoperative imaging—51% of patients undergoing surgery for patellar instability require chondroplasty for grade II/III lesions not fully appreciated preoperatively 4

Why Conservative Management Fails Here

Conservative treatment is appropriate only when:

• The knee is anatomically normal 1
• No osteochondral fracture exists on MRI 1
• No loose bodies are present 1, 2

Your patient fails all three criteria. Non-operative management in the presence of loose bodies and large cartilage defects leads to:

• Progressive cartilage damage from mechanical irritation 3, 2
• Chronic retropatellar pain 3
• Sport-limiting extensor mechanism impairment 3
• Higher risk of recurrent instability without MPFL reconstruction 2

Timing Considerations

• Surgery should be performed urgently (within 1-2 weeks) once swelling permits adequate examination and the patient can achieve near-full range of motion 1, 2
• Delaying surgery risks further cartilage damage from loose bodies and allows MPFL healing in an elongated position 2
• Early intervention provides better outcomes for concurrent osteochondral injuries, which are major contributors to adverse long-term results 3

Common Pitfalls to Avoid

• Do not rely on MRI to rule out loose bodies or cartilage defects—the poor sensitivity means arthroscopy will reveal additional pathology 4
• Do not attempt MPFL repair instead of reconstruction—repair has inferior outcomes and higher failure rates, especially with associated structural damage 2
• Do not defer surgery hoping for conservative success—the presence of loose bodies and large cartilage defects makes non-operative treatment inappropriate 1, 2
• Do not address only the MPFL without treating intra-articular pathology first—loose bodies and unstable cartilage must be managed before ligamentous reconstruction 2

Postoperative Rehabilitation

• Aggressive, multidimensional rehabilitation program is essential for return to taekwondo 3
• Early range of motion exercises while protecting the MPFL reconstruction 2
• Progressive weight-bearing and quadriceps strengthening 3, 2
• Sport-specific training before return to martial arts 3