Revisiting the Anteroinferior Iliac Spine: Is the Subspine Pathologic? A Clinical and Radiographic Evaluation

Karns, Michael R.; Adeyemi, Temitope F; Stephens, Andrew R.; Aoki, Stephen K.; Beese, M.; Salata, Michael J.; Maak, Travis G.

doi:10.1097/01.blo.0000533626.25502.e1

Cited by 21 publications

(24 citation statements)

References 29 publications

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“…Hetsroni et al (9) reported higher association of SSI with type II and type III AIIS by showing reduced hip flexion and internal rotation in these patients. Other studies found no correlation between AIIS morphologic characteristics and the SSI (11,27), and, similar to our research, some studies found a greater frequency of type I AIIS in their cohort with SSI (10,12). The elevated range of hip flexion and reduction in femoral anteversion have been attributed as predisposing factors for SSI independent of AIIS types (10,12).…”

supporting

confidence: 87%

“…Although numerous studies have described FAI imaging findings, few have focused on the association between symptoms and morphologic characteristics of AIIS, AIIS distance to the acetabular rim, and rectus femoris footprint (3,5,7,9,10). The role of AIIS as the only cause for SSI has also been questioned (11), and recent studies showed that SSI can occur in all types of AIIS, including normal AIIS (type I) (8,12).…”

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confidence: 99%

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MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology

et al. 2019

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Background:The MRI manifestations of subspine impingement (SSI) other than morphologic features of anterior inferior iliac spine (AIIS) have not been extensively explored and validated.Purpose: To determine the MRI findings associated with SSI, including AIIS morphologic features, femoral distal cam, and associated soft-tissue injuries. Materials and Methods:This is a retrospective study of symptomatic patients who underwent arthroscopic treatment for femoroacetabular impingement between December 2014 and March 2017, with preoperative MRI within 6 months before surgery. The SSI group included patients with clinical and intraoperative findings of SSI; the remaining patients comprised the non-SSI group. Preoperative MRI findings were independently assessed by two radiologists who were blinded to clinical information. Interreader agreement was assessed, and multivariable logistic regression was also used.Results: A total of 62 patients (mean age 6 standard deviation, 42.1 years 6 11.9; 38 women) were included. SSI was diagnosed in 20 of the 62 patients (32%) (mean age, 43 years 6 12); 42 patients (68%) did not have SSI (mean age, 41 years 6 10). Reader 1 detected distal cam in 16 of the 20 patients with SSI (80%) and eight of the 42 patients without SSI (19%), and reader 2 detected distal cam in 15 of the 20 patients with SSI (75%) and eight of the 42 patients without SSI (19%) (P , .001 for both). Reader 1 detected signs of impingement on the distal femoral neck (IDFN) in 18 of the 20 patients with SSI (90%) and seven of the 42 patients without SSI (16%), and reader 2 detected signs of IDFN in 13 of the 20 patients with SSI (65%) and nine of the 42 patients without SSI (21%) (P , .001 and P = .001, respectively). Reader 1 detected superior capsular edema in 15 of 20 patients with SSI (75%) and three of 42 patients without SSI (7%), and reader 2 detected superior capsular edema in 17 of 20 patients with SSI (85%) and 22 of 42 patients without SSI (52%) (P , .001 and P = .02, respectively). Distal cam was a predictor of SSI after adjustment for IDFN. Interreader agreement was substantial for distal cam (k = 0.80) and moderate for IDFN (k = 0.50). Conclusion:Soft-tissue injuries and osseous findings other than morphologic features of the anterior inferior iliac spine were associated with subspine impingement.

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confidence: 87%

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MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology

et al. 2019

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“…1 Subsequently, studies have described a subspine classification system, anatomic footprint, and clinical outcomes after arthroscopic subspine decompressions. [1][2][3][4][5][6] Despite this literature, there are still questions regarding the prevalence, existence, and whether or when decompression of the AIIS should be considered.…”

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confidence: 99%

Editorial Commentary: Subspine Hip Abnormalities: Exploring the Difference Between “Morphology” and “Impingement”

Larson¹

2019

Arthroscopy: The Journal of Arthroscopic & Related Surgery

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Subspine impingement has been increasingly recognized as a source of hip pain over the past 5 to 10 years. Some surgeons routinely perform subspine/anterior inferior iliac spine (AIIS) decompressions, whereas others rarely perform these procedures as part of an arthroscopic hip procedure. Subspine impingement has been implicated with high range-of-motion activities, various AIIS morphologies and deformities, and in the setting of persistent anterior hip pain after intra-articular anesthetic injections. Dynamic computed tomographic imaging has recently shown subspine impingement even with relatively normal AIIS morphology and in the setting of decreased femoral anteversion. These findings further emphasize the importance of understanding and defining relationships between morphology and impingement. Ultimately, subspine decompressions might be critical to achieve the best possible outcome after arthroscopic hip procedures in a subset of patients, but making the diagnosis remains challenging for clinicians.

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“…However, other authors have proposed that Type 1 hips may cause impingement against the distal femoral neck during excessive hip flexion, as is seen in ballet and high kick dancing ( 11 ). Meanwhile, the investigation by Karns et al ( 30 ) retrospectively analyzed AIIS morphology in 145 patients on anteroposterior and false profile radiographs, reporting no correlation between hip flexion, and internal rotation based on the AIIS classification type proposed by Hetsroni et al ( 10 ) Moreover, Balazs et al ( 31 ) found no difference in the distribution of Type 1 vs. Types 2 and 3 AIIS morphology when comparing symptomatic and asymptomatic patients, further questioning the association of AIIS in morphology in clinical extra-articular hip impingement. In addition, the authors reported difficulty distinguishing between Type 1 and Type 2 morphologies due to the confluence of the ilium wall and acetabular rim resulting in a lack of a distinct separation ( 31 ).…”

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confidence: 99%

Prevalence of Anterior Inferior Iliac Spine Dysmorphism and Development of a Novel Classification System: An Anatomic Study of 1,797 Cadaveric Specimens

et al. 2021

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Purpose: Subspine impingement occurs due to a morphologically abnormal anterior inferior iliac spine (AIIS), capable of causing impingement against the distal femoral neck. The purpose of this investigation was to determine the prevalence of AIIS dysmorphism based on specimen sex, race, and age, while introducing a novel anatomic-based classification system.Methods: A total of 1,797 adult cadaveric specimens (n = 3,594 hemipelvises) were analyzed. AIIS with the potential for subspine impingement (SSI) was recorded in each specimen by two independent authors. Specimens with AIIS dysmorphism were then reexamined to determine SSI subtype using a novel descriptive anatomic classification system.Results: AIIS dysmorphism was present in 6.4% (n = 115 of 1,797 specimens) of specimens and 5.2% (n = 186 of 3,594) of hemipelvises. Dysmorphism was significantly more common in male specimens (p = 0.04) and African–American specimens (p = 0.04). No significant overall difference in prevalence was appreciated based on specimen age (p = 0.89). Subtype classification found that 67% of hemipelvises possessed a columnar type AIIS, 30% were bulbous and 3% hook type. Males possessed a significantly higher prevalence of columnar type AIIS dysmorphism (p < 0.001). No significant overall differences in anatomic classification were appreciated based on race (p = 0.12) or when analyzed based on age (p = 0.34).Conclusion: AIIS dysmorphism was present in 6.4% of the 1,797 cadaveric specimens evaluated. African-American and male specimens possessed significantly higher prevalence of AIIS dysmorphism, with no significant difference based on specimen age. Columnar type AIIS dysmorphism was most common. Anatomic classification was not significantly different based on specimen race or age.Level of Evidence: Case Series, Level IV.

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Revisiting the Anteroinferior Iliac Spine: Is the Subspine Pathologic? A Clinical and Radiographic Evaluation

Abstract: Level III, diagnostic study.

Cited by 21 publications

References 29 publications

MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology

MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology

Editorial Commentary: Subspine Hip Abnormalities: Exploring the Difference Between “Morphology” and “Impingement”

Prevalence of Anterior Inferior Iliac Spine Dysmorphism and Development of a Novel Classification System: An Anatomic Study of 1,797 Cadaveric Specimens

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