Endoscopic Assisted Percutaneous Fixation of Anterior Inferior Iliac Spine Avulsion Fracture, Surgical Technique.

Avulsion fractures of the anterior inferior iliac spine rarely occur in adolescent athletes during rectus femoris contractions or eccentric muscle lengthening while the growth plate is still open. Currently, there are no official guidelines in the literature on the treatment indications of this type of fracture or the type of surgical technique to be used. Nowadays, young and athletic patients desire a quick return to their previous activities, which makes surgical treatment a reasonable choice. Open reduction and internal fixation with an anterior approach are usually recommended when the avulsion fragment has more than 1.5-2 cm displacement on plain radiographs. However, ORIF is associated with a higher risk of heterotopic ossifications and increases the risk of damage to the LFCN. An endoscopic technique was designed to reduce these complications. This technical note describes a procedure of percutaneous fixation to AIIS through 3 endoscopic portals that could potentially minimize complications associated with an open surgical dissection, allowing anatomic reduction under direct visualization.

Traumatic avulsion of the anterior superior and inferior iliac spines in adult: A case report.

Introduction: Avulsion fractures of the anterior superior and inferior iliac spines are rare fractures. They are mostly observed in adolescents during sports accidents, traumatic forms are even more exceptional. Case report: Here we report a case of simultaneous and homolateral avulsion fractures of both anterior superior and anterior inferior iliac spines in a 35-year-old male adult after a motorcycle accident. Surgical treatment using an open reduction and fixation of the two spines was performed with very good functional outcomes. Surgical management of iliac spine avulsion fractures allows recovery of the subsequent level of sports activity in most cases. Conclusion: Avulsion fractures of the anterior superior and inferior iliac spines are rare fractures. Surgical management of iliac spine avulsion fractures allows recovery of the subsequent level of sports activity in most cases. Orthopedic treatment is still used for the management of this type of injury, thus comparative studies are needed to refine the criteria for surgery.

Reevaluation of the surgical indications for anterior inferior iliac spine avulsion fractures in an acute setting - A narrative review of the current literature.

Purpose: The anterior inferior iliac spine (AIIS) is a frequent site of avulsion fracture in the pelvis, and these lesions could be observed mainly in teenage athletes. The present study aimed to re-evaluate the appropriate acute surgical treatment of AIIS avulsion fractures considering the three-dimensional anatomy of the supracetabular region. Methods: This study evaluated current evidence of AIIS avulsion fracture treatments and outcomes. A literature search was done in the following databases: PubMed, SCOPUS, Embase, and Cochrane Library. All relevant information was used in this review. Results: Several studies have shown how conservative treatment of these injuries lead to excellent outcomes, even when there is radiological evidence of displacement. However, only some surgeons describe clinical and radiological follow-up beyond six months. On the other side, recent studies have demonstrated the efficacy of arthroscopic or open procedures to solve a frequent cause of extra-articular femur-acetabular impingement (FAI) syndrome associated with previous AIIS avulsion fractures, the so-called sub-spine impingement. The acute surgical indication in AIIS avulsion fractures should be considered according to the three-dimensional anatomy of the supracetabular region, especially in young patients with high functional demands. Conclusions: Three-dimensional assessment allows accurate evaluation of the position and dislocation of the fragment, predicting the risk of complications related to conservative treatment and guiding toward surgical indication only when appropriate.

Pelvic morphologies of developmental dysplasia and primary osteoarthritis on range of motion after total hip arthroplasty.

Bony impingement, especially in the anterior inferior iliac spine (AIIS) after total hip arthroplasty (THA), may cause dislocation. However, the influence of AIIS characteristics on bony impingement after THA is not fully understood. Thus, we aimed to determine the morphological characteristics of AIIS with developmental dysplasia of the hip (DDH) and primary osteoarthritis (pOA) and to evaluate its effect on range of motion (ROM) after THA. Hips from 130 patients who underwent THA, including pOA were analyzed. In total, we had 27 male and 27 female participants with pOA, and 38 male and 38 female participants with DDH. The horizontal distances of AIIS from teardrop (TD) were compared. In the computed tomography simulation, flexion ROM was measured, and its relationship to the distance between TD and AIIS was investigated. DDH had a more medial (male: DDH, 36.9 ± 5.8; pOA, 45.5 ± 6.1; p < 0.001) (female: DDH, 31.5 ± 10.0; pOA, 36.2 ± 4.7; p < 0.001) position of AIIS than pOA. In the male with pOA group, flexion ROM was significantly smaller than that in the other groups, and there was a correlation between flexion ROM and horizontal distances (r = -0.543; 95% confidence interval = -0.765 to -0.206; p = 0.003). AIIS position is a factor that limits ROM during flexion after THA, particularly in males. Further studies are required to develop surgical strategies for cases of impingement at the AIIS site after THA. Level of evidence: Ð¨, retrospective comparative study.

Outcomes of Arthroscopic Decompression of the Anterior Inferior Iliac Spine: A Systematic Review and Meta-analysis.

BACKGROUND: Anterior inferior iliac spine (AIIS) impingement has been increasingly recognized as a source of extra-articular impingement and hip pain. However, no aggregate data analysis of patient outcomes after AIIS decompression has been performed. PURPOSE: To evaluate outcomes after arthroscopic AIIS decompression. STUDY DESIGN: Meta-analysis; Level of evidence, 4. METHODS: A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were queried for all English-language studies reporting outcomes of arthroscopic AIIS decompression performed in isolation or in conjunction with hip impingement correction surgery. After screening, 10 articles were included. The indications for AIIS decompression were recorded, and weighted mean improvements in patient-reported outcome (PRO) scores, complication rates, and revision rates were calculated. RESULTS: A total of 547 patients (311 women; 57%) were identified, with a total of 620 operative hips. The mean age was 28.42 ± 5.6 years, and the mean follow-up was 25.22 ± 11.1 months. A total of 529 hips (85%) underwent AIIS decompression, 530 hips (85%) underwent femoral osteochondroplasty, and 458 hips (74%) underwent labral repair. Of the patients, 13% underwent bilateral AIIS decompression. The mean modified Harris Hip Score improved from 61.3 ± 6.9 to 88.7 ± 4.7 postoperatively (change, 27.4 ± 5.7 points; P < .001), the Hip Outcome Score-Activities of Daily Living improved from 67.2 ± 10.6 to 91.1 ± 3.2 postoperatively (change, 24.0 ± 8.0 points; P = .001), and the Hip Outcome Score-Sports Specific Subscale improved from 36.8 ± 19.2 to 82.8 ± 3.8 postoperatively (change, 46.0 ± 18.2 points; P = .002). The pooled risk of postoperative complications was 1.1% (95% CI, 0.1%-2.1%), and the pooled risk of needing revision surgery was 1.0% (95% CI, 0.1%-2.0%). No complication was directly attributed to the AIIS decompression portion of the procedure. CONCLUSION: PROs improved significantly after hip arthroscopy with AIIS decompression, with a low risk of postoperative complications and subsequent revision surgeries. Failure to identify extra-articular sources of hip pain in outcomes of femoroacetabular impingement syndrome, including from the AIIS, could lead to poorer outcomes and future revision surgery.

Imaging Diagnosis, Prevalence, and Clinical Outcomes of Arthroscopic Surgery for Anterior Inferior Iliac Spine Impingement: A Systematic Review and Meta-analysis.

Background: Subspine impingement, or anterior inferior iliac spine (AIIS) impingement, is a type of extra-articular pathology associated with femoroacetabular impingement syndrome and often requires subsequent arthroscopic surgery. Purpose: To examine the diagnostic accuracy, prevalence, and clinical outcomes of arthroscopic treatment for AIIS impingement. Study Design: Systematic review; Level of evidence, 4. Methods: The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 checklist was applied. We searched for studies on the prevalence, diagnostic accuracy, and results of surgical treatment for AIIS impingement. For each included study, data synthesis and statistical analysis were performed to identify pooled prevalence, calculate clinical outcome scores, and estimate adverse events. The QUADAS (a quality assessment tool for diagnostic accuracy studies) was used to assess the quality of the diagnostic accuracy studies, and the Risk of Bias Assessment tool for Nonrandomized Studies was used to assess the quality of the studies on arthroscopic treatment efficacy. Results: Out of an initial 791 studies, 23 were included. AIIS impingement was diagnosed by plain radiography with 76% to 86% sensitivity, 3-dimensional computed tomography with 80% to 81.8% sensitivity, magnetic resonance imaging with 80% sensitivity, and ultrasound with 92.5% sensitivity. For patients who underwent hip arthroscopy, the pooled prevalence of AIIS impingement was 18%. Significant improvement between pre- and postoperative clinical outcomes was observed: 25.75 points for the modified Harris hip score (mHHS), 46.88 points for the Hip Outcome Score-Sport subscale, 20.85 points for the Nonarthritic Hip Score, and -2.92 points for the pain visual analog scale. The minimal clinically important difference on the mHHS was exceeded by 94% of patients. The pooled incidence of surgical complications was 1%. Of 6 included studies on diagnostic accuracy, 2 were identified as having a low risk of bias, and 4 included >2 factors with a high risk of bias. All 9 included studies on treatment outcomes had at least 1 factor with a high risk of bias. Conclusion: Several imaging modalities assist in the diagnosis of AIIS impingement. The overall prevalence of AIIS impingement in patients that underwent hip arthroscopy was 18%. Clinical outcomes after arthroscopic AIIS decompression were generally favorable, with a relatively low rate of surgical complications.

Simultaneous Bilateral Anterior Inferior Iliac Spine Avulsion Injury in an Adolescent Cross-Country Runner.

Introduction: Pelvic apophyseal injuries are common in young athletes where muscle strength exceeds the tensile strength of the physis. Sequential bilateral injuries are exceedingly rare, and little is known of their mechanism. Case Presentation: A 15-year-old male cross-country runner presented with bilateral hip pain after sprint training. The patient describes going "flat out" and "overstriding" before collapsing with immediate pain. MRI imaging confirmed an acute bilateral Anterior Inferior Iliac Spine Injury (AIIS). Conservative management included protected weight-bearing, a hip strengthening program and graded return to play. At 6 months, the patient returned to full sporting activities with no symptoms. Conclusion: We present a unique case of bilateral AIIS avulsion that offers insight into the potential mechanisms and adds to the evidence that these injuries may be managed successfully with conservative treatment.

Subspine Hypertrophy: Higher Incidence of Symptomatic versus Asymptomatic Hips in Patients with Unilateral Femoroacetabular Impingement.

OBJECTIVE: To compare the difference of anterior inferior iliac spine (AIIS) and subspine hypertrophic deformity between symptomatic and asymptomatic hips in patients traditionally diagnosed with femoroacetabular impingement (FAI), and investigate the correlation of subspine decompression with AIIS variation and subspine hypertrophic deformity. METHODS: We retrospectively reviewed 70 patients with unilateral symptomatic FAI who underwent hip arthroscopy. The operative hips and contralateral hips naturally formed the symptomatic groups and asymptomatic control groups, respectively. The morphometric comparison of the hip joint was performed between the operative and contralateral sides of each patient. Radiological assessment was performed by two observers (an experienced musculoskeletal radiologist and an experienced surgeon). Three-dimensional (3D)-CT images of each patient were blindly reviewed to determine the AIIS variation and subspine hypertrophic deformity. Reformatted two-dimensional (2D)-CT images and anterior-posterior (AP) pelvic plain radiographs were blindly reviewed to determine FAI-related morphological measurements. Moreover, the surgical assessment was reviewed by one experienced surgeon to interpret whether subspine decompression was performed. The correlation of subspine decompression with AIIS variation and subspine hypertrophy was analyzed. RESULTS: Out of 70 patients with unilateral symptomatic FAI, 37 were males (52.9%) and 23 (32.9%) had symptoms involving the left hip. The mean age was 39.3 ± 10.4 years and the mean BMI was 24.3 ± 3.6. The distribution of AIIS variants in symptomatic hips did not differ significantly from that in asymptomatic hips (χ2 = 3.092, P = 0.213). Twenty-nine hips in the symptomatic group (41.4%) and 12 hips in the asymptomatic group (17.1%) were identified as positive for subspine hypertrophy. The incidence of positive subspine hypertrophy was significantly higher in the symptomatic hips compared to the asymptomatic hips (χ2 = 9.968, P = 0.002). FAI-related morphological parameters including α angle, lateral center-edge angle, acetabular anteversion, crossover sign, and Tonnis grade were highly symmetrical and did not show significant differences between symptomatic and asymptomatic hips. Fifty-four of 70 hips (77.1%) had labral tears extended to the acetabular rim corresponding to the AIIS. Forty-seven hips of 70 hips (67.1%) underwent subspine decompression, which was significantly correlated with AIIS variation and subspine hypertrophic deformity (P = 0.019 and 0.001, respectively). CONCLUSION: Subspine hypertrophic deformity was found to be more common in symptomatic side vs asymptomatic side in patients with unilateral symptomatic femoroacetabular impingement. Subspine hypertrophy may be considered as an underlying indication for subspine decompression besides low-lying AIIS.

Iliac anatomy in women with developmental dysplasia of the hip: Measurements using three-dimensional computed tomography.

BACKGROUND: We aimed to clarify the iliac anatomy in developmental dysplasia of the hip using three-dimensional computed tomography. METHODS: The distance between two points along each anatomical portion of the ilium, including the acetabular center, were compared between patients in the dysplasia and control groups. RESULTS: There were no significant differences in the upper part of the ilium between the groups. However, three distances that included the acetabular center were significantly shorter in the dysplasia group than in the control group. CONCLUSIONS: Our study suggests that bone dysplasia occurs in the ilium near the acetabulum, not in the iliac wings.

Sonographic evaluation of anterior inferior iliac spine morphology demonstrates excellent accuracy when compared to false profile view.

PURPOSE: To compare ultrasound examination to false profile radiographs in identification and classification of AIIS morphology. The study hypothesis stated that sonographic imaging of the AIIS correlates well to AIIS morphology seen on false profile radiographs. METHODS: Fifty-three hips in 30 consecutive patients met the inclusion criteria. A single, fellowship trained, orthopedic surgeon performed an ultrasound on all of the patients to evaluate the AIIS morphology. The patients underwent standing false profile radiographs. The US and radiographic images were independently reviewed and classified according to Hetsroni classification of AIIS morphology by two senior, fellowship trained, orthopedic surgeons. Agreement between the two raters was calculated for each imaging modality (inter-rater agreement) as well as the agreement between the rating in each modality by the same rater ("inter-method" agreement). RESULTS:  The agreement between the raters (inter-rater agreement) for morphologic evaluation of the AIIS by means of FP view was 88.8% (p < 0.001) and that by means of US was 81.5%(p < 0.001). The overall accuracy of the US compared to the FP view was 92.3% (48/52) for both rater 1 and 2. CONCLUSION:  This study showed near-perfect agreement in analyzing the morphology of the AIIS in a group of patients with hip pathology. Office sonographic evaluation of the AIIS is reliable and, therefore, may be routinely utilized in the clinic setting avoiding unnecessary radiation exposure to the patient. LEVEL OF EVIDENCE: Level II.

Osteochondroma formation after avulsion fracture of anterior inferior iliac spine: A case report.

BACKGROUND: Hip avulsion fractures occur mostly during adolescence when actions such as kicking or running cause forceful contraction of attached muscle. Osteochondroma is benign tumor that mostly occurs at the metaphysis of a long bone, being usually asymptomatic. CASE SUMMARY: A 15-year-old patient experienced feeling and sound of a break while kicking a ball in soccer game three years prior to his visit to our hospital. A simple X-ray revealed an avulsion fracture of the apophysis of the anterior inferior iliac spine (AIIS). Later in the follow-up X-ray, a palpable mass was found and demonstrated by magnetic resonance imaging to be a pedunculated osteochondroma in the superolateral aspect of the AIIS. For surgical treatment, we performed osteotomy for surgical excision and excisional biopsy. A mass with smooth surface and an unclear superolateral AIIS border was found intraoperatively. Pathologic exam showed definite diagnosis of osteochondroma. Postoperatively, discomfort during hip flexion was improved, and the hip joint range of motion during walking was recovered at the last follow-up, which was three weeks after the surgery. CONCLUSION: This is a rare case to demonstrate relevant previous trauma history prior to the formation of osteochondroma.

Evaluation of anterior inferior iliac spine impingement after hip arthroscopic osteochondroplasty using computer simulation analysis.

BACKGROUND: Anterior inferior iliac spine (AIIS) impingement is an important risk factor for revision hip arthroscopy. Although a morphological classification system is available, evaluating AIIS impingement with respect to joint kinematics remains a challenge. PURPOSE: To use computer simulation analysis to ascertain the prevalence of AIIS impingement before and after osteochondroplasty. METHODS: A total of 35 joints from 30 cases (20 males and 10 females; average age: 43.3 ± 13.7 years) were analyzed. All joints had cam morphology and underwent hip arthroscopic osteochondroplasty. A three-dimensional model of each joint was constructed pre- and postoperatively. Joint kinematic simulation software (ZedHip®, Lexi, Tokyo) was used to identify the impingement point on the acetabular side and the incidence (expressed as a percentage) of AIIS impingement calculated. Radiographic and clinical evaluation was performed pre- and postoperatively. RESULTS: AIIS impingement was observed postoperatively in six joints but preoperatively in only one joint. The rate of AIIS postoperative impingement was significantly higher than that of preoperative impingement. All impingement points were located on the inferior aspect of the AIIS apex. However, there were no significant differences between the AIIS impingement and non-impingement groups in terms of clinical outcome. CONCLUSION: The incidence of AIIS impingement after osteochondroplasty was 17% by computer simulation analysis. Osteochondroplasty may result in subsequent AIIS impingement.

Anterior Iliac Spine Avulsion Fracture Treatment Options in Young Athletes.

Purpose: The aim of this research is to perform a literature review of the treatments available for the anterior iliac spines avulsion fracture on the young subjects. Material and Methods: We performed a systematic literature search for studies on spines avulsion fractures in young subjects from January 1, 2013, to February 2018; abstracts were screened by a single reviewer. For those studies meeting the eligibility criteria, full-text articles were obtained. Results: From 112 studies found only six articles were included in this systematic review. All the studies belonged to level IV of scientific evidence. 64 patients suffered an anterior inferior iliac spine fracture while patients 36% patients suffered an anterior superior iliac spine fracture. 93.2% underwent conservative treatment and 6.8% underwent surgery. Conclusions: The anterior iliac spine avulsions fractures are rare injuries that occur in young male athletes and the conservative option is the most selected treatment modality.

Arthroscopic anterior inferior iliac spine decompression does not alter postoperative muscle strength.

PURPOSE: The purpose of this study was to assess the additional effect of anterior inferior iliac spine (AIIS) decompression on knee extensor and hip flexor strength and compare functional outcomes after arthroscopic FAI correction with and without AIIS decompression. METHODS: Sixty patients who underwent arthroscopic FAI correction surgery were divided into two groups matched for AIIS morphology: 31 patients who underwent arthroscopic FAI surgery only (without AIIS decompression) (FAI group) (AIIS Type I; n = 5, Type II; n = 26, Type III; n = 0) and 29 patients who underwent arthroscopic FAI surgery with AIIS decompression (AIIS group) (AIIS Type I; n = 5, Type II; n = 24, Type III; n = 0). Knee extensor and hip flexor strength were evaluated preoperatively and at 6 months after surgery. Patient-reported outcome (PRO) scores using the modified Harris hip score (MHHS), the nonarthritic hip score (NAHS) and iHOT-12 were obtained preoperatively and at 6 months after surgery. RESULTS: In the AIIS group, there was no significant difference between knee extensor strength pre- and postoperatively (n.s.). In the AIIS group, hip flexor strength was significantly improved postoperatively compared to preoperative measures (p < 0.05). In the FAI group, there were no significant improvements regarding muscle strength (n.s.). While there were no significant differences of preoperative and postoperative MHHS and NAHS between both groups (MHHS; n.s., NAHS; n.s.), the mean postoperative iHOT-12 in the FAI group was inferior to that in the AIIS group. (p < 0.01). The revision surgery rate for the AIIS group was significantly lower compared with that in the FAI group (p < 0.05). CONCLUSION: Anterior inferior iliac spine decompression, as a part of an arthroscopic FAI corrective procedure, had a lower revision surgery rate and did not compromise knee extensor and hip flexor strength, and it improved clinical outcomes comparable to FAI correction without AIIS decompression. AIIS decompression for FAI correction improved postoperative PRO scores without altering the muscle strength of hip flexor and knee extensor. LEVEL OF EVIDENCE: III.

The prevalence of a prominent anterior inferior iliac spine.

INTRODUCTION: Impingement of the prominent anterior inferior iliac spine (AIIS) against the femoral neck has recently been described as another type of impingement. The purpose of this study is to provide a distribution of AIIS types using the classification proposed by Hetsroni and thus report on the prevalence of prominent types. MATERIALS AND METHODS: A total of 400 patients were included in the study with an average age 27.3 ± 6.9 years (range 18-40). All patients received a whole-body polytrauma computer tomography (CT) scan in the emergency room (ER) upon arrival. The classification of AIIS proposed by Hetsroni et al., which describes three morphological types, was used. Type II and III were grouped as prominent types. The measurements were performed in all three planes by two examiners. RESULTS: Male to female ratio was 71:29. Type I was observed in 367 (91.7%) patients. Type II was observed in 31 (7.8%) patients and type III was observed in 2 (0.5%) patients, unilaterally. Prominent types were much more prevalent in men (10.5%) than in women (2.6%). The CT assessment demonstrated excellent intra- and interreliability (overall: 0.926, I/II: 0.906, III: 1.000). CONCLUSION: A young population demonstrates a prevalence of a prominent AIIS of 11.5%. Prominent AIIS is more common in men than in women.

Anterior Inferior Iliac Spine Morphology: Comparison of Symptomatic Hips With Femoroacetabular Impingement and Asymptomatic Hips.

OBJECTIVE: The objective of our study was to compare anterior inferior iliac spine (AIIS) morphology in symptomatic hips with femoroacetabular impingement (FAI) and in asymptomatic hips, determine the prevalence of impingement morphology in patients with a radiographic "crossover" sign, and identify potential risk factors for having impingement morphology. MATERIALS AND METHODS: For this retrospective study, we identified consecutive symptomatic hips with FAI (n = 54) and asymptomatic hips (n = 35) in patients who underwent CT from 2015 to 2017. Two radiologists blindly and independently evaluated 3D CT images of each hip and graded the AIIS morphology according to the Hetsroni classification scheme. The prevalence of AIIS morphology types was calculated. Associations of AIIS morphology types with symptoms and the crossover sign were evaluated with a chi-square test. A multivariable logistic regression determined risk factors for abnormal AIIS morphology (i.e., type 2 or 3). RESULTS: There was no difference in the prevalence of AIIS morphology types for symptomatic hips with FAI versus asymptomatic hips (p = 0.44) or for hips with a positive versus those with a negative crossover sign (p = 0.21). There was moderate interobserver agreement (κ = 0.44) and good-to-excellent intraobserver agreement (κ = 0.67 and 0.90) for grading AIIS morphology. Age, sex, femoral version, acetabular version, alpha angle, lateral center edge angle, and the crossover sign were not significant risk factors for abnormal AIIS morphology in patients with FAI (p = 0.11-0.79). CONCLUSION: There is no difference in AIIS morphology between symptomatic hips with FAI versus asymptomatic hips or between hips with and those without the radiographic crossover sign. Age, sex, and other FAI parameters are not risk factors for developing AIIS impingement morphology.

Anterior inferior iliac spine morphology: quantitative and qualitative assessment in an asymptomatic population.

PURPOSE: To assess the prevalence of anterior inferior iliac spine (AIIS) types, and to investigate the quantitative measurements that characterize AIIS morphology in an asymptomatic adult population. METHODS: In this prospective study, 358 hips from 179 consecutive subjects (age range, 19-82 years; 91 males, 88 females), who underwent CT examination for reasons other than hip problems and were negative for hip impingement test, were analyzed. AIIS types were determined (1, flat wall of the ilium between distal end of AIIS and acetebular rim; 2, bony eminence between distal end of AIIS and acetebular rim; and 3, extension of AIIS to the anterior superior acetebular rim) and AIIS tip angle (TA), direct distance (DD) of the anterior acetabular rim to AIIS as well as projectional distances in vertical (VD) and horizontal (HD) planes were measured. Age- and gender-related factors were searched using two-way ANOVA test under three age groups (18-39, 40-59, and ≥ 60 years). RESULTS: There were 238 (66.5%) type 1, 118 (33.0%) type 2, and two (0.5%) type 3 AIISs, with significant difference between AIIS types among age groups and genders (P < 0.001). VD and DD showed age- and gender-related (P < 0.001, P < 0.001), and TA demonstrated gender-related differences (P < 0.001). Inter-observer agreement was good for TA and moderate to poor for other measurements. CONCLUSIONS: Type 1 AIIS is the most common shape across all age groups in adult females and in young and middle-aged adult males. TA, DD, and VD might be reliably used for the evaluation of AIIS morphology.

S-1 alar/iliac screw technique for spinopelvic fixation.

Spinopelvic fixation provides an important anchor for long fusions in spinal deformity surgery, and it is also used in the treatment of other spine pathologies. Iliac screws are known to sometimes require reoperation due to pain resulting from hardware prominence and skin injury. S-2 alar/iliac (S2AI) screws do not often require removal, but they may provide inadequate fixation in select cases. In this paper the authors describe a technique for S-1 alar/iliac screws that may be used independently or as a supplement to S2AI screws. A preliminary biomechanical analysis and 2 clinical case examples are also provided.

Morphological variation of the anterior inferior iliac spine affects hip range of motion in flexion after rotational acetabular osteotomy.

PURPOSE: Reduced range of motion (ROM) in flexion and internal rotation are associated with impaired activities of daily living (ADL) after rotational acetabular osteotomy (RAO). This study focused on the morphological variation of the anterior inferior iliac spine in developmental dysplasia of the hip (DDH) and its impact on post-operative bony ROM after RAO. This study aimed to investigate the association between bony ROM after RAO and pre-operative morphological factors of the pelvis and femur, including a positional variation of the anterior inferior iliac spine. METHODS: Bony ROM in 52 patients with DDH was assessed after virtual RAO using computed tomography (CT). Post-operative acetabular coverage was set at lateral and anterior centre-edge angles of 30° and 55°, respectively. The position of the anterior inferior iliac spine was classified as higher or lower. RESULTS: Multiple regression analysis revealed that the lower anterior inferior iliac spine and higher femoral neck shaft angle were significantly associated with the lower flexion angle after RAO. Lower femoral anteversion, higher femoral neck shaft angle and higher alpha angle at the anterosuperior part were significantly associated with lower internal rotation angle at 90° flexion after RAO. CONCLUSION: Therefore, morphological variation of the anterior inferior iliac spine affected bony ROM in flexion and that of the femoral neck affected bony ROM in internal rotation at flexion after RAO.

Anterior Inferior Iliac Spine Deformity as a Cause for Extra-articular Hip Impingement in Young Athletes After an Avulsion Fracture: A Case Report.

Extra-articular hip impingement from prior traumatic injury to the anterior inferior iliac spine (AIIS) is an uncommon cause of groin pain in young athletes. Currently, the most common treatment for this injury is arthroscopic decompression. However, hip arthroscopy is not universally available and requires advanced skills. We report 2 cases of the development of extra-articular hip impingement from unusual bony exostoses off the AIIS after traumatic injury in 2 young athletes who underwent open surgical resection. The multidisciplinary sports medicine team should be aware of the development of extra-articular impingement from traumatic injury to the AIIS and that open surgical resection is a viable alternative to arthroscopic decompression.