Comparison Between Performance of Disease-Specific and Region-Specific Patient-Reported Outcome Measures in...

Patellofemoral instability (PFI) is common in adolescents and may require surgical treatment. Patient-reported outcome scores (PROs) are frequently used to evaluate outcomes after treatment. Commonly used PROs for PFI include disease-specific Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and region-specific measures such as the Kujala Anterior Knee Pain Scale (Kujala), Pediatric International Knee Documentation Committee Subjective Knee Form (Pedi-IKDC), and Knee injury and Osteoarthritis Outcome Score (KOOS).

The study aimed to compare the performance of disease-specific and region-specific PROs in adolescents after PFI surgery, and to evaluate their sensitivity to change. It was hypothesized that disease-specific PROs would perform better than region-specific PROs.

Case series; Level of evidence, 4.

The JUPITER (Justifying Patellar Instability Treatment by Early Results) study database was used to evaluate PROs in 256 adolescents (263 knees) aged ≤18 years who underwent surgical treatment for PFI. Four commonly used PRO scores were analyzed at baseline and at least 1 year postoperatively. Statistical analysis included comparisons between pre- and postoperative scores, calculation of minimal clinically important difference (MCID), correlations among the 4 scores, and evaluation of their sensitivity to change, floor effects, and ceiling effects.

The median age was 15 years. Isolated medial patellofemoral ligament reconstruction was the most common procedure. The mean BPII 2.0 scores were lower at baseline and postoperatively, and showed the most substantial change at 1-year follow-up. There was a moderate correlation between the BPII 2.0 and the Kujala, Pedi-IKDC, and KOOS scores, and a strong correlation among the latter 3 scores. All scores were more sensitive to change among those at the lower 50th percentile of baseline scores. The BPII 2.0 was the only PRO that did not exhibit ceiling effects at follow-up.

When comparing the performance of disease-specific (BPII 2.0) and region-specific (Kujala, Pedi-IKDC, and KOOS) PROs, the BPII 2.0 was found to be the most sensitive to change after PFI surgery in adolescents, and the only scale that did not have a ceiling effect at baseline and 1-year follow-up. There was a moderate correlation-and thus limited interchangeability-between the BPII 2.0 and the Kujala, Pedi-IKDC, and KOOS scores, both at baseline and at 1-year follow-up, and a strong correlation among the latter 3 knee-specific PROs. The BPII 2.0 should be considered the PRO of choice when evaluating adolescent patients with PFI.