Acetabular Version Increases After Closure of the Triradiate Cartilage Complex

• Published in: Clinical orthopaedics and related research 2017-04, Vol.475 (4), p.983-994
• Main Authors: Albers, Christoph E., Schwarz, Andrea, Hanke, Markus S., Kienle, Karl-Philipp, Werlen, Stefan, Siebenrock, Klaus A.
• Format: Article
• Language: English
• Subjects: Acetabulum - diagnostic imaging; Acetabulum - growth & development; Adolescent; Age Factors; Cartilage, Articular - diagnostic imaging; Cartilage, Articular - growth & development; Child; Conservative Orthopedics; Female; Femoracetabular Impingement - diagnostic imaging; Femoracetabular Impingement - etiology; Femur Head - diagnostic imaging; Femur Head - growth & development; Healthy Volunteers; Hip; Humans; Magnetic Resonance Imaging; Male; Medicine; Medicine & Public Health; Orthopedics; Predictive Value of Tests; Prospective Studies; Risk Factors; Sports Medicine; Surgery; Surgical Orthopedics; Symposium: 2016 Bernese Hip Symposium; Time Factors
• ISSN: 0009-921X; 1528-1132
• DOI: 10.1007/s11999-016-5048-0

Background Although the etiology of primary femoroacetabular impingement (FAI) is considered developmental, the underlying pathogenic mechanisms remain poorly understood. In particular, research identifying etiologic factors associated with pincer FAI is limited. Knowledge of the physiologic growth patterns of the acetabulum during skeletal maturation might allow conclusions on deviations from normal development that could contribute to pincer-related pathomorphologies. Questions/purposes In a population of healthy children, we asked if there were any differences related to skeletal maturation with regard to (1) acetabular version; (2) acetabular depth/width ratio; and (3) femoral head coverage in the same children as assessed by MRIs obtained 1 year apart. Methods We prospectively compared 129 MRIs in 65 asymptomatic volunteers without a known hip disorder from a mixed primary/high school population (mean age, 12.7 years; range, 7–16 years). All participants underwent two MRI examinations separated by a minimum interval of 1 year. Based on the status of the triradiate cartilage complex (open versus closed [TCC]), all hips were allocated to the following groups: “open-open” = open TCC at both MRIs (n = 45 hips [22 bilateral]); “open-closed” = open TCC at initial and closed TCC at followup MRI (n = 26 hips [13 bilateral]); and “closed-closed” group = closed TCC at both MRIs (n = 58 hips [29 bilateral]). We assessed acetabular version in the axial plane at five different locations (5, 10, 15, 20 mm below the acetabular dome and at the level of the femoral head) as well as three-dimensional (3-D) acetabular depth/width ratio and 3-D femoral head coverage on six radial MRI sequences oriented circumferentially around the femoral neck axis. Using analysis of variance for multigroup comparisons with Bonferroni adjustment for pairwise comparisons, we compared the results between the initial and followup MRI examinations and among the three groups. Results Acetabular version was increased in hips of the “open-closed” group at the followup MRI compared with the initial MRI at 5 mm (−6 ± 4.6 [95% confidence interval {CI}, −7.6 to −3.6] versus −1 ± 5.0 [95% CI, −3.3 to 0.7]; p