What is the recurrence rate of patellar dislocation after surgical intervention, specifically Medial Patellofemoral Ligament (MPFL) reconstruction, in a 15-year-old patient?

Recurrence Rate of Patellar Dislocation After MPFL Reconstruction in Adolescents

The recurrence rate of patellar dislocation after Medial Patellofemoral Ligament (MPFL) reconstruction in a 15-year-old patient is approximately 2-3%, making it a highly effective surgical intervention for preventing recurrent instability. 1

Epidemiology and Risk Factors

• Patellar dislocation is one of the most common knee injuries in adolescents, with anatomical predisposition detected in almost all cases 2
• Approximately one-third (35.2%) of patients with initial patellar dislocation will experience one or more recurrences if treated conservatively 2
• Nearly half (48.6%) of dislocations occur during physical activities, particularly ball sports 2
• Anatomical risk factors that predispose to recurrent dislocation include:
  • Abnormal sulcus angle
  • Patellar and trochlear dysplasia
  • Increased patellar height
  • Increased tibial tubercle-trochlear groove (TT-TG) distance 2

Surgical Outcomes by Procedure Type

MPFL Reconstruction with Gracilis Tendon

• MPFL reconstruction using gracilis tendon autograft with a modified double-patellar tunnel technique shows excellent long-term results:
  • Recurrence rate of only 2.5% (2 out of 80 knees) at minimum 5-year follow-up 1
  • Significant improvement in functional outcomes:
    • Mean Kujala score increased from 69.4 to 96.1
    • Mean Lysholm score increased from 73.5 to 95.3 1

MPFL Reconstruction with Other Techniques

• Standard MPFL reconstruction using gracilis tendon with femoral interference screw and patellar anchors:
  • Recurrence rate of 3.3% (3 out of 90 knees) at average 24.3-month follow-up 3
  • Significant improvement in mean Kujala score from 53.88 to 86.24 3
  • Significant correction of patellar tilt on radiographic assessment 3

MPFL Repair (Not Reconstruction)

• MPFL repair (as opposed to reconstruction) shows significantly higher failure rates:
  • Recurrence rate of 28% (8 out of 29 knees) at average 4-year follow-up 4
  • Five patients (17%) required reoperation due to recurrent instability 4
  • Nonanatomical repair at the medial femoral condyle was a significant risk factor for failure 4

Comparison of Surgical vs. Conservative Management

• Conservative treatment of primary patellar dislocation without serious concomitant injuries shows:
  • Recurrence rate of 41.7% in conservatively treated knees 2
• Surgical treatment shows significantly better outcomes:
  • Recurrence rate of 29.6% with surgical procedures other than MPFL reconstruction with tendon graft 2
  • No recurrences (0%) reported after MPFL reconstruction with tendon graft in one comparative study 2

Key Considerations for Adolescent Patients

• Anatomical factors should be carefully evaluated when planning surgical intervention for a 15-year-old patient 2
• Surgical indications in adolescents include:
  • Recurrent dislocations after failed conservative treatment
  • Presence of osteochondral flake fractures
  • Significant anatomical predisposing factors 2
• Proper surgical technique is critical for success:
  • Anatomical placement of the femoral tunnel between the adductor magnus tubercle and medial epicondyle 3
  • Secure fixation with interference screws or anchors 3
  • Additional procedures may be necessary when TT-TG distance exceeds 20mm 3

Conclusion

For a 15-year-old patient undergoing MPFL reconstruction for patellar instability, the expected recurrence rate is approximately 2-3% with modern surgical techniques using tendon autograft. This represents a significant improvement over both conservative management and older surgical repair techniques, making MPFL reconstruction the current standard of care for recurrent patellar dislocation in adolescents.