Lateral to Medial Joint Space Ratio is Predictive of Survivorship after Primary Hip Arthroscopy
2Orthopedics, American Hip Institute, USA
Purpose:
To assess whether preoperative joint space measures would be predictive of survivorship in patients undergoing hip arthroscopy for femoroacetabular impingement (FAI).
Methods:
Data on consecutive patients who underwent hip arthroscopy between February 2008 and February 2018 were retrospectively reviewed. To be eligible for final analysis, patients were required to have preoperative radiographs for joint space measurements and data indicating conversion to a total hip arthroplasty (THA), hip resurfacing, or neither; at a minimum of two years after primary hip arthroscopy. Patients were split into two groups depending on whether they underwent conversion joint arthroplasty or not. Patient variables were compared between the groups. A multivariate logistic regression analysis and receiver operator curve (ROC) were used to evaluate the correlation between joint space measurements and conversion to THA.
Results:
A total of 1,885 primary arthroscopy cases were included in this study. The multivariate regression analysis found preoperative lateral-to-medial joint space ratio (L/M ratio) to be the strongest predictive factor of survivorship after primary hip arthroscopy (OR = 2.084, CI95% = 1.239 – 3.503, p = 0.006). The ROC curve for the model demonstrated acceptable discrimination with an area under the curve (AUC) of 0.792. Patients with an L/M ratio ≥ 0.75 had a survivorship rate of 91.7% compared to a rate of 75% for patients with an L/M ratio < 0.75 (OR: 3.68).
Conclusions:
This study found that the most significant factor in predicting survivorship at 2-years after undergoing primary hip arthroscopy was preservation of lateral joint space, as noted by a larger lateral-to-medial joint space ratio.