A Narrow Posterior Joint Space on a False Profile Radiograph Does Not Correlate With Posterior Joint Cartilage Degeneration in Hip Preservation Patients

Abstract

PurposeTo evaluate whether a narrow posterior joint space (<2 mm) correlated with posterior joint cartilage degeneration in the hip preservation patient population. MethodsA retrospective chart review of 155 consecutive hip arthroscopy cases by a single surgeon (SKA) from March 2012 to February 2013 was performed. Patients were included in the study if they had an adequate perioperative false profile radiograph and clear intraoperative arthroscopic images of the posterior hip joint. The narrowest posterior joint space (NPJS) width and the directly posterior, posterosuperior, superior, and anterosuperior joint space widths were measured on the false profile radiograph. Femoral and acetabular cartilage of the posterior hip joint were graded according to the International Cartilage Repair Society (ICRS) classification system using arthroscopic images obtained at the time of surgery. The cartilage grades of patients with <2 mm NPJS were compared with cartilage grades of patients with ≥2 mm NPJS. ResultsThere was no difference in cartilage grading between patients with <2 mm NPJS (19 patients) and those with ≥2 mm NPJS (81 patients) (P = .905). The mean age of patients with NPJS ≥2 mm and <2 mm was 34.0 (median 31.2; interquartile range [IQR] 23.7, 42.9) and 38.7 (median 43.0; IQR 26.1, 50.9) respectively, and was not statistically different (P = .183). No correlation between cartilage grade and NPJS measurement was found (P = .374). ConclusionIn this predominantly cam-type femoroacetabular impingement patient cohort, our findings indicate there is no correlation between a <2 mm posterior hip joint narrowing seen on false profile radiographs and posterior hip cartilage degeneration confirmed with arthroscopy. Although posterior arthritis can be visualized on a false profile radiograph, a posterior joint space measurement <2 mm should not be interpreted as isolated posterior joint wear and should not be considered a hip arthroscopy contraindication. Level of EvidenceLevel IV, case series.