Dean K Matsuda1, Charito P Schnieder2, Bantoo Sehgal3. 1. Kaiser West Los Angeles Medical Center, Los Angeles, California, U.S.A. Electronic address: dean.k.matsuda@kp.org. 2. Kaiser West Los Angeles Medical Center, Los Angeles, California, U.S.A. 3. Essentia Health, Fargo, North Dakota, U.S.A.
Abstract
PURPOSE: The purpose of this study was to evaluate the concept of cam femoroacetabular impingement (FAI) occurring medial to the classic anterolateral (AL) quadrant. METHODS: Forty-four patients met the inclusion criteria of cam FAI and underwent arthroscopic AL femoroplasty. Goniometric measurements of intraoperative hip internal rotation (HIR) in 90° of hip flexion and 0° of adduction were obtained. Thirty patients (14 male and 16 female), comprising the substance of this study, exhibited HIR of less than 40° after AL femoroplasty and underwent further anteromedial (AM) femoroplasty with subsequent repeat measurement of HIR. Nonparametric statistical analysis was performed. RESULTS: Preoperative HIR averaged 20.8° (range, 10° to 29°); intraoperative HIR averaged 29.5° (range, 18° to 39°) after AL femoroplasty and 42.7° (range, 32° to 61°) after additional AM femoroplasty. The gain in HIR after AL femoroplasty was 8.7° (range, 2° to 23°) (P < .0001). The further gain in HIR after AM femoroplasty was 13.2° (range, 2° to 22°) (P < .0001). The overall gain in HIR after AL and AM femoroplasty was 21.9° (range, 13° to 38°) (P < .0001). A consistent landmark termed the resident's ridge of the hip accompanied all cases of AM cam impingement. CONCLUSIONS: Femoroplasty of the AM "critical corner" may improve cam decompression and supports the concept of cam impingement extending beyond the classic AL quadrant of the proximal femur. LEVEL OF EVIDENCE: Level IV, therapeutic case series.
PURPOSE: The purpose of this study was to evaluate the concept of cam femoroacetabular impingement (FAI) occurring medial to the classic anterolateral (AL) quadrant. METHODS: Forty-four patients met the inclusion criteria of cam FAI and underwent arthroscopic AL femoroplasty. Goniometric measurements of intraoperative hip internal rotation (HIR) in 90° of hip flexion and 0° of adduction were obtained. Thirty patients (14 male and 16 female), comprising the substance of this study, exhibited HIR of less than 40° after AL femoroplasty and underwent further anteromedial (AM) femoroplasty with subsequent repeat measurement of HIR. Nonparametric statistical analysis was performed. RESULTS: Preoperative HIR averaged 20.8° (range, 10° to 29°); intraoperative HIR averaged 29.5° (range, 18° to 39°) after AL femoroplasty and 42.7° (range, 32° to 61°) after additional AM femoroplasty. The gain in HIR after AL femoroplasty was 8.7° (range, 2° to 23°) (P < .0001). The further gain in HIR after AM femoroplasty was 13.2° (range, 2° to 22°) (P < .0001). The overall gain in HIR after AL and AM femoroplasty was 21.9° (range, 13° to 38°) (P < .0001). A consistent landmark termed the resident's ridge of the hip accompanied all cases of AM cam impingement. CONCLUSIONS: Femoroplasty of the AM "critical corner" may improve cam decompression and supports the concept of cam impingement extending beyond the classic AL quadrant of the proximal femur. LEVEL OF EVIDENCE: Level IV, therapeutic case series.