Orthobiologic Injections for the Treatment of Hip Osteoarthritis and the Minimal Clinically Important Difference

Purpose: The Minimal Clinically Important Difference (MCID) is important to assess the clinical relevance of treatment results. The aim of this study was to establish the MCID values for VAS, WOMAC, and HHS scores in patients treated with intra-articular orthobiologic injections for hip osteoarthritis (OA). Methods: Ninety-six patients (62.5% men, 37.5% women, 48.3 ± 12.0 years old) affected by hip OA and treated with orthobiologic injections were assessed through VAS for pain, WOMAC, and HHS scores at baseline and at 6 and 12 months after the injection. MCID values were calculated for each score at both follow-ups. Baseline variables, including age, sex, and Tonnis grade, were collected to investigate their possible influence on the improvement in terms of MCID achievement rate. Results: The MCID values obtained in the current study were 10.1, 6.6, and 6, respectively for VAS pain, WOMAC, and HHS at 6 months after the injective treatment. Overall, these thresholds remained stable from 6 to 12 months of follow-up, being 10.2, 7.7, and 6.3, respectively. While an overall statistical improvement was documented for all scores, most patients did not reach clinically relevant benefits according to the identified MCID. Low OA grade and female patients were found to reach more likely the MCID. Conclusion: This study defined the MCID thresholds ​​for VAS pain, WOMAC score, and HHS for patients affected by hip OA treated with orthobiologic injections. This can help clinicians interpreting the outcome obtained with injective treatments beyond the statistical difference and in light of clinically relevant benefits for patients.