Anterior Inferior Iliac Spine Morphology Research Articles

Comparison of Anterior Inferior Iliac Spine Morphology Between Femoroacetabular Impingement and Developmental Dysplasia of the Hip: A Cohort Study in Symptomatic Patients

Comparison of Anterior Inferior Iliac Spine Morphology Between Femoroacetabular Impingement and Developmental Dysplasia of the Hip: A Cohort Study in Symptomatic Patients

Magnetic Resonance Imaging Is Not Reliable in Classifying Anterior Inferior Iliac Spine Morphology Compared to 3-Dimensional Computerized Tomography

The purpose of this study is to determine the reliability of standard magnetic resonance imaging (MRI) evaluation of AIIS morphology compared with three-dimensional (3D) computerized tomography (CT) (reference standard). Sixty hips in 30 patients met the inclusion criteria. The images were reviewed and classified by two fellowship-trained orthopedic surgeons. A second imaging viewing session was conducted in the same manner for validation of AIIS evaluation. The agreement and accuracy indices between the two raters were calculated for each imaging modality (inter-rater agreement) as well the agreement across the imaging modality for each rater (intermethod agreement). The inter-rater agreement for the morphological evaluation of the AIIS for the first session according to 3D CT was .553 (P < .05) and by means of MRI was .0163 (P < .05). The inter-rater agreement for the second session by means of 3D CT was .449 (P < .05) and according to MRI was 0 (P < .05). The inter-method agreement for rater 1 for the first session was .04 (P < 0.05), while the agreement for rater 2 was .016 (P < .05). The intermethod agreement for rater 1 on the second session was .35 (P < 0.05), while that of rater 2 was .297(P < .05). The overall accuracy of MRI compared to 3D CT for rater 1 for the first session was .531, .490, and .959 for types I, II, III respectively and .551, .531, and .980 for the second session for types I, II, and III respectively. The overall accuracy of MRI compared to 3D CT for rater 2 for the first session was .551, .469, and .918 for types I, II, III respectively and .633, .592, and .918 for the second session for types I, II, and III, respectively. MRI evaluations and subsequent classifications of AIIS morphology demonstrated a poor to slight correlation compared with that of the reference standard of 3D CT. Level II, retrospective diagnostic study.

Anterior Inferior Iliac Spine Morphology and Outcomes of Hip Arthroscopy in Soccer Athletes: A Comparison to Nonkicking Athletes

To describe the anterior inferior iliac spine (AIIS) morphology and clinical outcomes following arthroscopic surgical decompression in a group of high-level soccer athletes presenting with symptomatic hip impingement when compared with a control group of nonkicking athletes. From 2009 to 2012, we retrospectively reviewed our prospective hip registry for soccer athletes who underwent arthroscopic treatment for femoroacetabular impingement (FAI) with 2-year follow-up, comparing with a control group of nonkicking athletes. Demographics were collected and radiographic studies (plain radiograph and computed tomographic scan) reviewed for several parameters, including AIIS morphology. Patient-reported outcome scores, including modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Sport-Specific Subscale (HOS-SSS), and International Hip Outcome Tool-33 (iHOT-33), were administered preoperatively, at 6months, and at 1, 2, and 3years postoperatively. Twenty-six soccer players (34 hips) and 87 nonkicking athletes (115) hips were identified. Demographics, including age (19.2 ± 4.1 vs 20.1 ± 3.8years) and gender distribution (53.8% vs 51.7% male), were similar between the soccer and nonkicking athletes (P= .288, .849). Eighty-four percent of soccer players demonstrated some abnormality of the AIIS extending to (type II, 52%) or below the anterior acetabular rim (type III, 32%), compared with 52% nonkicking athletes (P < .001). At a mean follow-up of 35months (range, 24-57months) there was significant improvement in all outcome scores in both groups from pre- to postoperation (P < .001). There was no evidence of differences in outcome scores between groups (mHSS: 89 ± 14.6 vs 88.2 ± 14.4, P= .804; HOS-ADL: 94.1 ± 9.1 vs 92.2 ± 11.1, P= .431; HOS-SSS: 86 ± 17.1 vs 81.3 ± 24.3, P= .362) with the exception of iHOT-33 (81.7 ± 19 vs 70.3 ± 23.6, P= .027). High-level soccer players have a significantly higher rate of subspine impingement compared with nonkicking athletes. There should be a high index of suspicion when treating soccer players for FAI, where appropriate recognition and treatment of subspine impingement can yield excellent clinical results. Level III, retrospective case-control study.

Anatomic Footprint of the Direct Head of the Rectus Femoris Origin: Cadaveric Study and Clinical Series of Hips After Arthroscopic Anterior Inferior Iliac Spine/Subspine Decompression

The purposes of this study were to define the anatomy of the anterior inferior iliac spine (AIIS) and its relation to the footprint of the rectus femoris tendon and to evaluate on the clinical outcomes after AIIS/subspine decompression. The rectus origin was dissected and detached in 11 male cadaveric hips with a mean age of 54.3 ± 14.3 years (range, 33 to 74 years). The proximal-distal and medial-lateral extent of the footprint and its relation to the AIIS and acetabular rim were evaluated, with the 12-o'clock position defined as directly lateral at the insertion of the indirect head of the rectus tendon and the 1- to 6-o'clock positions defined as anterior acetabular positions. To assess the safety and efficacy of subspine decompression for AIIS deformity, clinical correlation of a series of 163 AIIS decompressions (mean age, 27.8 years; age range, 14 to 52 years) performed from January 2011 to January 2012 was completed, and outcome scores, strength deficits, and ruptures were assessed by manual muscle testing and postoperative radiographs. All patients presented with symptomatic FAI with proximal femoral and/or acetabular deformity and type 2 (131 hips) or type 3 (32 hips) AIIS morphology as defined by Hetsroni et al. The mean proximal-distal and medial-lateral distances for the rectus origin footprint were 2.2 ± 0.1 cm (range, 2.1 to 2.4 cm) and 1.6 ± 0.3 cm (range, 1.2 to 2.3 cm), respectively. There was a characteristic bare area at the anteromedial AIIS. On the clock face, the lateral margin (1-o'clock to 1:30 position) and medial margin (2-o'clock to 2:30 position) of the AIIS and the indirect head of the rectus (12 o'clock) were consistent for all specimens. In the clinical series, 163 AIIS decompressions were performed for symptomatic subspine impingement. The mean modified Harris Hip Score was 63.1 points (range, 21 to 90 points) preoperatively compared with 85.3 points (range, 37 to 100 points) at a mean follow-up of 11.1 ± 4.1 months (range, 6 to 24 months) (P < .01). Short Form 12 scores improved significantly from a mean of 70.4 (range, 34 to 93) preoperatively to a mean of 81.3 (range, 31 to 99) postoperatively (P < .01). The mean pain score on a visual analog scale also improved significantly from a mean of 4.9 (range, 0.1 to 8.6) preoperatively to a mean of 1.9 (range, 0 to 7.8) postoperatively (P < .01). The mean alpha angle improved from 61.5° (range, 35° to 90°) preoperatively to 49° (range, 35° to 63°) postoperatively on anteroposterior radiographs and from 71° (range, 45° to 90°) preoperatively to 44.3° (range, 37° to 60°) postoperatively on lateral radiographs. No short- or long-term hip flexion deficits or rectus femoris avulsions were noted with up to 2 years' follow-up. The origin of the rectus femoris tendon is broad on the AIIS and protective against direct head detachment with subspine decompression. This broad origin and consistent bare area anteromedially on the AIIS can be readily used by surgeons to perform a safe AIIS resection in cases of symptomatic impingement. Arthroscopic subspine decompression in addition to osteoplasty for symptomatic cam- and/or pincer-type FAI deformities can reliably improve outcome scores without significant hip flexion deficits or AIIS/rectus femoris avulsions. The direct head of the rectus tendon has a broad insertion on the AIIS, and an area devoid of tendon provides a "safe zone" for subspine decompression in cases of symptomatic AIIS impingement.

Anterior Inferior Iliac Spine Morphology Correlates with Hip Range of Motion: A CT-based Classification System and Dynamic Hip Model

The AIIS can be reproducibly classified into 3 morphological types (i.e. I, II, III) based on 3D CT reconstructions. When hips in patients with signs of FAI are matched for version and alpha angle, AIIS types II and III are associated with decrease in hip flexion and internal rotation, supporting the rationale to consider AIIS decompression for types that extends to and below the acetabular rim.

Anterior Inferior Iliac Spine Morphology Correlates With Hip Range of Motion: A Classification System and Dynamic Model

The anterior inferior iliac spine (AIIS) contributes to hip dysfunction in patients with symptomatic impingement and resection of a prominent AIIS can reportedly improve function. However, the variability of the AIIS morphology and whether that variability correlates with risk of associated symptomatic impingement are unclear. We characterized AIIS morphology in patients with hip impingement and tested the association between specific AIIS variants and hip range of motion. We evaluated three-dimensional CT reconstructions of 53 hips (53 patients) with impingement and defined three morphological AIIS variants: Type I when there was a smooth ilium wall between the AIIS and the acetabular rim, Type II when the AIIS extended to the level of the rim, and Type III when the AIIS extended distally to the acetabular rim. A separate cohort of 78 hips (78 patients) with impingement was used to compare hip range of motion among the three AIIS types. Mean hip flexion was limited to 120°, 107°, and 93° in hips with Type I, Type II, and Type III AIIS, respectively. Mean internal rotation was limited to 21°, 11°, and 8° in hips with Type I, Type II, and Type III AIIS, respectively. When the AIIS is classified into three variants based on the relationship between the AIIS and the acetabular rim in patients with impingement, Type II and III variants are associated with a decrease in hip flexion and internal rotation, supporting the rationale for considering AIIS decompression for variants that extend to and below the rim.