Joint Space Narrowing in Patients with Femoroacetabular Impingement: A Matched Cohort Study of Military versus Civilian Patients.

INTRODUCTION

Decreased hip joint space has been associated with poorer outcomes after hip arthroscopy. The purpose of this study was to determine if a difference exists in hip joint degenerative findings in military versus civilian patients with FAI.

METHODS

A single surgeon's case series was reviewed to identify all patients undergoing primary hip arthroscopy for treatment of FAI. All active duty military personnel were included in the study group. A cohort of civilian patients matched for age, gender, lateral center edge (LCE) angle, and alpha angle was identified and included as the control group. The hip joint space was measured at the medial and lateral extents of the acetabular sourcil and the center of the sourcil. The Tonnis grade for osteoarthritis was recorded for each patient. Labral tear size as well as femoral head and acetabular chondromalacia grading were obtained from operative records.

RESULTS

A total of 229 patients that underwent primary hip arthroscopy for FAI were identified. 46(20.1%) were active duty military personnel. A well-matched cohort of 46 civilian patients was identified. There was no statistical difference in age (35.0, 34.7 years), gender (31 males, 15 females in both groups), BMI (26.8, 27.6), LCE angle (31.0, 31.5), and alpha angle (64.9, 64.9) between the civilian and military groups. Joint space was narrower in the military group in each of the three measured locations (Superomedial 3.8 mm vs 4.2 mm, p = 0.025; Superior 4.0 mm vs 4.4 mm, p = 0.013; Superolateral 4.4 mm vs 4.9 mm, p = 0.043).

CONCLUSION

Military patients with FAI may have increased joint space narrowing compared to otherwise similar civilian patients. Femoral and acetabular chondromalacia are found in similar frequencies in military and civilian populations, however the grading system utilized accounts for the presence but not the size of high grade lesions.

LEVEL OF EVIDENCE: Level 3.