Early MCID achievement is associated with better long-term outcomes following arthroscopy for femoroacetabular impingement.

Abstract

Purpose: To determine whether early improvement is associated with long-term outcomes following arthroscopy for femoroacetabular Impingement and establish a threshold above which would indicate sustained improvement. It was hypothesised that those who display improvements early would report better long-term outcomes than those who did not report meaningful change at 1 year, allowing further targeted intervention where necessary.

Methods: An examination of patients (Tonnis 0,1) undergoing primary arthroscopy between January 2009 and March 2014, with 10-year review, was conducted. Four hundred and fifteen hip arthroscopy cases in 355 patients were included. The minimal clinically important difference (MCID) for the modified Harris Hip score (mHHS) at 1 year was calculated using the percentage of possible improvement (POPI) method. Patients were grouped as early improvers (EI) or non-improvers (NI) based on whether they achieved MCID at 1 year or not. Survival, revision rate, and the patient acceptable symptom state (PASS) were compared between groups using a Kaplan-Meier curve and chi-squared analysis.

Results: One year MCID achievement required an improvement from pre-operative mHHS of at least 47%; 79% of cases achieved MCID (EI), and 21% did not (NI). At 10 years, there were six total hip replacements in the EI group compared to 16 in the NI group (survival 98% vs. 82%, p < 0.001). Revision rates were lower in the EI group (6% vs. 12%, p = 0.005), and the EI group had higher levels of PASS achievement (86% vs. 68%, p < 0.001). Regression models indicated that MCID achievement at 1 year, reduced the odds of replacement and revision surgery while increasing the odds of PASS achievement at 10 years.

Conclusion: Higher survival rates, higher PASS rates and lower revision procedures were observed in EI. When accounting for other known confounding factors, improving by a minimum of 47% of what a patient could achieve in the mHHS at 1 year predicts superior outcomes long-term. For those patients failing to achieve this important improvement threshold, clinicians could consider introducing additional rehabilitation or interventions that may further improve recovery and potentially increase the likelihood of a better longer-term outcome.

Level of evidence: Level IV.