When should surgery be performed in an 18‑year‑old male with a spontaneously reduced patellar dislocation, post‑traumatic hemarthrosis, MRI showing disrupted medial patellofemoral ligament, grade I cartilage defect of the medial patellar facet, and multiple loose osteochondral fragments?

Timing of Surgery for Acute Patellar Dislocation with Significant Intra-articular Pathology

Surgery should be performed urgently within the first few weeks after injury—ideally within 2-4 weeks—to address the disrupted MPFL, large cartilage defect, and loose bodies, as early arthroscopic intervention allows for optimal cartilage fragment fixation and prevents secondary damage from loose bodies while the cartilage remains viable for repair. 1, 2

Rationale for Early Surgical Intervention

The presence of multiple high-risk features in this case mandates urgent rather than delayed surgery:

• Large cartilage defect with loose bodies: Arthroscopic studies demonstrate that 40-66% of acute patellar dislocations have significant osteochondral defects not visible on plain radiographs, and these fragments remain viable for fixation only in the acute phase 3, 2

• Hemarthrosis requiring arthrocentesis (55ml): This substantial blood volume indicates significant intra-articular injury and correlates with cartilage damage requiring surgical intervention 3

• Disrupted MPFL: While isolated MPFL tears can sometimes be managed conservatively, the combination with large cartilage defects necessitates surgical stabilization to prevent recurrent instability and progressive cartilage damage 1

Specific Surgical Timing Window

The optimal window is within 2-4 weeks post-injury, based on the following evidence:

• Cartilage fragments remain viable for fixation in the acute phase, with successful outcomes reported when surgery is performed early 1
• Delayed surgery beyond 4-6 weeks significantly reduces the success of cartilage fragment fixation, as the fragments lose viability 1
• Early arthroscopic treatment (within weeks) shows 83-93% good-to-excellent results when performed acutely 2

Surgical Approach

The procedure should include:

• Arthroscopic evaluation and treatment of cartilage defects: For the large medial patellar facet defect, fixation using transosseous PDS sutures is preferred over screws (avoids second surgery for hardware removal), with mean Kujala scores of 89.3 and IKDC scores of 87.2 reported 1

• Removal of loose bodies: All scattered loose bodies must be excised, with corresponding craters debrided 2

• MPFL reconstruction: This should be performed concomitantly using allograft (such as semitendinosus) to address the underlying instability 4

• Avoid isolated lateral release: Studies show that adding lateral release to acute patellar dislocation treatment decreases outcomes (73% vs 93% good-excellent results) and increases recurrence rates (14% overall, all in the lateral release group) 2

Critical Pitfalls to Avoid

• Delaying surgery beyond 4 weeks: Cartilage fragment viability decreases significantly, reducing fixation success rates 1

• Conservative management in this case: While some first-time patellar dislocations without significant cartilage damage can be managed conservatively, the presence of large cartilage defects (4.1 cm² mean in similar cases) and loose bodies makes conservative treatment inappropriate 1

• Performing lateral release: This outdated practice increases recurrence rates and worsens outcomes in acute traumatic dislocations 2

Post-operative Protocol

• Immobilization for 4 weeks in a knee immobilizer or plaster splint to allow cartilage healing 3, 1
• Gradual range of motion exercises after 4 weeks
• Return to pre-injury activities expected in 72-82% of patients with proper cartilage fixation 1