Anterior Inferior Iliac Spine Research Articles

Indirect Head of the Rectus Femoris Tendon as a Graft for Segmental Hip Labral Reconstruction: An Anatomic, Radiographical, and Biomechanical Study in Comparison With Iliotibial Labral Reconstruction.

The indirect head of the rectus femoris (IHRF) tendon has been used as an autograft for segmental labral reconstruction. However, the biomechanical properties and anatomic characteristics of the IHRF, as they relate to surgical applications, have yet to be investigated. To (1) quantitatively and qualitatively describe the anatomy of IHRF and its relationship with surrounding arthroscopically relevant landmarks; (2) detail radiographic findings pertinent to IHRF; (3) biomechanically assess segmental labral reconstruction with IHRF, including restoration of the suction seal and contact pressures in comparison with iliotibial band (ITB) reconstruction; and (4) assess potential donor-site morbidity caused by graft harvesting. Descriptive laboratory study. A cadaveric study was performed using 8 fresh-frozen human cadaveric full pelvises and 7 hemipelvises. Three-dimensional anatomic measurements were collected using a 3-dimensional coordinate digitizer. Radiographic analysis was accomplished by securing radiopaque markers of different sizes to the evaluated anatomic structures of the assigned hip.Suction seal and contact pressure testing were performed over 3 trials on 6 pelvises under 4 different testing conditions for each specimen: intact, labral tear, segmental labral reconstruction with ITB, and segmental labral reconstruction with IHRF. After IHRF tendon harvest, each full pelvis had both the intact and contralateral hip tested under tension along its anatomic direction to assess potential site morbidity, such as tendon failure or bony avulsion. The centroid and posterior apex of the indirect rectus femoris attachment are respectively located 10.3 ± 2.6 mm and 21.0 ± 6.5 mm posteriorly, 2.5 ± 7.8 mm and 0.7 ± 8.0 mm superiorly, and 5.0 ± 2.8 mm and 22.2 ± 4.4 mm laterally to the 12:30 labral position. Radiographically, the mean distance of the IHRF to the following landmarks was determined as follows: anterior inferior iliac spine (8.8 ± 2.5 mm), direct head of the rectus femoris (8.0 ± 3.9 mm), 12-o'clock labral position (14.1 ± 2.8 mm), and 3-o'clock labral position (36.5 ± 4.4 mm). During suction seal testing, both the ITB and the IHRF reconstruction groups had significantly lower peak loads and lower energy to peak loads compared with both intact and tear groups (P = .01 to .02 for all comparisons). There were no significant differences between the reconstruction groups for peak loads, energy, and displacement at peak load. In 60° of flexion, there were no differences in normalized contact pressure and contact area between ITB or IHRF reconstruction groups (P > .99). There were no significant differences between intact and harvested specimen groups in donor-site morbidity testing. The IHRF tendon is within close anatomic proximity to arthroscopic acetabular landmarks. In the cadaveric model, harvesting of the IHRF tendon as an autograft does not lead to significant donor-site morbidity in the remaining tendon. Segmental labral reconstruction performed with the IHRF tendon exhibits similar biomechanical outcomes compared with that performed with ITB. This study demonstrates the viability of segmental labral reconstruction with an IHRF tendon and provides a detailed anatomic description of the tendon in the context of an arthroscopic labral reconstruction. Clinicians can use this information during the selection of a graft and as a guide during an arthroscopic graft harvest.

Biomechanical comparative study on external fixators of new configurations in the treatment of Tile C pelvic injury

To compare the biomechanical properties of several anterior pelvic ring external fixators with two new configurations in the treatment of Tile C pelvic fractures, in order to evaluate the effectiveness of the new configurations and provide a reference for their clinical application. A finite element model of a Tile C pelvic ring injury (unilateral longitudinal sacral fracture and ipsilateral pubic fracture) was constructed. The pelvis was fixed with iliac crest external fixator (IC), anterior inferior iliac spine external fixator (AIIS), combination of IC and AIIS, combination of anterior superior iliac spine external fixator (ASIS) and AIIS, and S1 sacroiliac screw in 5 types of models. The stability indices of the anterior and posterior pelvic rings under vertical longitudinal load, left–right compression load and anterior–posterior shear load were quantified and compared. In the simulated bipedal standing position, the results of the vertical displacement of the midpoint on the upper surface of the sacrum are consistent with the displacement of the posterior rotation angle, and the order from largest to smallest is IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. The longitudinal displacement of IC is greater than that of the other models. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter is smaller. In the simulated semi-recumbent position, the vertical displacement and posterior rotation angle displacement of the midpoint on the upper surface of the sacrum are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Under the simulated left–right compression load state, the lateral displacements of the highest point of the lateral sacral fracture end are consistent with the highest point of the lateral pubic fracture end, and the order from large to small is S1 screw, IC, AIIS, ASIS + AIIS and IC + AIIS, among which the displacements of S1 screw and IC are larger, and the displacements of ASIS + AIIS and IC + AIIS are similar and smaller than those of other models. The displacements of IC + AIIS are smaller than those of ASIS + AIIS. Under the simulated anterior–posterior shear load condition, the posterior displacements of the highest point of the lateral sacral fracture end and the highest point of the lateral pubic fracture end are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Among them, the displacements of IC and AIIS are larger. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter are smaller. For the unstable pelvic injury represented by Tile C pelvic fracture, the biomechanical various stabilities of the combination of IC and AIIS are superior to those of the external fixators of conventional configurations. The biomechanical stabilities of the combination of ASIS and AIIS are also better than those of the external fixators of conventional configurations, and slightly worse than those of the combination of IC and AIIS. Compared with sacroiliac screw and conventional external fixators, the lateral stabilities of IC + AIIS and ASIS + AIIS are particularly prominent.

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.

Avulsions in adolescent soccer players: preliminary results of radiographic, ultrasonographic and magnetic resonance findings

Objectives: The main objective of this study was to characterize soccer related avulsions radiologically. The secondary objectives were to describe the athletes' clinical profile and other musculoskeletal changes associated with avulsions. Materials and methods: Cross-sectional study with adolescent athletes from a Brazilian team soccer academy. Inclusion criteria were age between 11 and 16 years and clinical and magnetic resonance imaging (MRI) diagnosis of avulsion. Exclusion criteria were exams with an unacceptable technical standard and absence of clinical data. Four radiologists revised the exams consensually (two for each method). The equipment used was a General Electric (GE) US scanner, model Logic 10, and a 1.5 T MRI GE scanner, Optima MR 360 model, and a Shimadzu RX scanner, Radspeed MC model. Results and discussion: Nine showed signs of avulsion from a sample of 37 athletes. The mean age was 13.1 years, and all were male. Four athletes were injured during the matches (44.4%), and another five were in training (55.6%). Clinically, one injury was considered mild (11.1%), two moderate (22.2%), and six severe (66.7%). The anatomical locations and frequencies of avulsions were: five in the anterior inferior iliac spine (AIIS) (55.6%), two in the ischiatic tuberosity (IT) (22.2%), and two in the iliac crest (22.2%). Ultrasonography (US) was performed in 10 cases and detected seven avulsions (77.8%). All lesions not detected by US occurred at the IT. A pelvic radiograph was performed in seven cases and was positive in five athletes (77.8%). Undetected cases occurred at the AIIS. Avulsions occurred in isolation in eight cases (88.9%), simultaneously with indirect trauma in three (33.3%) and direct trauma in two (22.2%). Conclusion: In adolescent soccer players, a quarter of traumatic injuries are avulsions, which are more common at the AIIS. US proved ineffective in identifying some IT lesions and radiography, some others at the AIIS.

Multivariate linear-mixed analysis of changes in anterior inferior iliac spine impingement incidence with posterior pelvic tilt: a computer simulation study

ABSTRACT It is well known that increased posterior tilt of the pelvis is an effective strategy for avoiding impingement of the femur with the pelvis during movement. Daily repetitive collisions become mechanical loads, and the more frequently they occur, the more tissue damage and pain they cause. Therefore, reducing the rate of occurrence of impingement is important to avoid aggravation of symptoms. This study aimed to evaluate the effects of changes in posterior pelvic tilt on the risk of impingement between the femur and the anterior inferior iliac spine (AIIS)/subspine in various functional postures. Patients with femoroacetabular impingement syndrome (FAIS) who were candidates for hip arthroscopic osteochondroplasty between October 2013 and June 2020 were included. A three-dimensional reconstructed model was used to simulate the incidence of impingement at 12 hip positions required for activities of daily living. We predicted value of the spatial incidence of impingement assumed that hip motion should exceed 130/30 degrees without impingement. Impingement was measured at three pelvic positions: an anterior tilt of 10°, in the functional pelvic plane and a posterior tilt of 10°. Multivariate linear-mixed models were used to assess the effect of covariate-adjusted posterior pelvic tilt on the impingement incidence in the AIIS region. AIIS type, center-edge angle, acetabular version and femoral version were used as covariates. The impingement rates and locations of the three pelvic tilt postures were assessed. Seventy-eight patients (60 males and 18 females; average age, 46 ± 15.1 years) with FAIS were analyzed. A multivariate linear-mixed model revealed a coefficient of −0.8% (95% confidence interval −0.9 to −0.7%; P < 0.001) for posterior pelvic tilt. Thus, posterior pelvic tilt affects AIIS impingement incidence. After adjusting for anatomical effects, the posterior pelvic tilt should be addressed to avoid impingement.

MORPHOLOGICAL STUDY OF ANTERIOR INFERIOR ILIAC SPINE IN A SAMPLE OF HEMIPELVIS FROM SOUTH INDIAN POPULATION

Objective: Abnormal morphology of anterior inferior iliac spine (AIIS) contributing to repeated femoroacetabular impingement, leading to functional limitation at the hip joint and chronic groin pain has been reported recently. The present study examines the prevalence of the morphologically different AIIS in south Indian population. Methods: This was an observational and cross-sectional study conducted by analyzing dry hemipelvises of South Indian population at the Department of Anatomy of a tertiary care teaching hospital between July 2022 and June 2023. The specimens were analyzed independently by first and second authors, to determine the prevalence of different morphologies of AIIS based on Morales-Avalos classification. Data were entered into Microsoft Excel and analyzed. Results: A total of 150 hemipelvises were analyzed. Type 2A was observed in 46.42% (n=65/140). Abnormal morphology was seen more on the left side hemipelvises (41.42%, n=58/140). Conclusions: Type 2A of AIIS was more prevalent in South Indian population and more prevalent on the left side hemipelvis. Demonstrating the different morphologies of AIIS helps in understanding their role in subspine hip impingement.

Fluoroscopy-guided triple hip block for patients with hip osteoarthritis: A new approach.

Hip osteoarthritis (OA) is found in approximately 10% of the population and often causes disability and social limitations in elderly patients. Intra-articular injections are among the most frequently applied interventional treatments for the hip joint. Femoral and obturator sensorial nerve blocks have also been reported to be effective for both diagnostic and therapeutic purposes. A single needle insertion was performed for the blockage of the hip joint and sensory branches. For the sensory branch of the femoral nerve, the needle is advanced at nearly a 45-degree angle toward below the anterior inferior iliac spine near the anterolateral edge of the hip joint. For the sensory branch of the obturator nerve, the needle is advanced at nearly an angle of 45 degrees toward the area below the junction of the pubis and ischium. Finally, for joint injection, the same needle was advanced toward the midline of the anterior femoral head-neck junction at a steeper angle, and blocks were applied. Three patients with hip osteoarthritis were injected with this method and well-being was achieved in a 3-month follow-up. We think that blockage of the hip joint and peripheral sensory branches with a single needle insertion is a fast and effective method. However, prospective controlled studies are needed to determine the efficacy and safety of the method.

Osteochondromas Gone Pelvic: A Case Report of Concurrent Tibial Osteoblastoma and incidental detection of multiple pelvic Osteochondromas on bone scan.

In a unique clinical presentation, a 20-year-old female with a known left distal Tibial Osteoblastoma (previously treated via curettage) developed pain and weight-bearing difficulties in her left lower limb six months later. Subsequently bone scan revealed a unprecedented clinical presentation: residual activity in the treated Osteoblastoma alongside additional foci of increased tracer uptake on skeletal scintigraphy, localized to the bilateral anterior superior and inferior iliac spines. Subsequent radiographs confirmed sessile bony outgrowths in these locations, consistent with multiple pelvic Osteochondromas (an uncommon variant). Notably, these Osteochondromas lacked associated radiolucencies or cortical destruction. Further MRI confirmed the Osteochondroma diagnosis. Interestingly, the patient declined surgical intervention for the asymptomatic Osteochondromas, prioritizing ongoing treatment for the primary Osteoblastoma. This case highlights the rare co-occurrence of these distinct tumor types in an uncommon usual pelvic location, emphasizing the importance of patient centered treatment approach based on patient preferences and clinical context.

Locating an iliac cortical window for reduction of an acetabular dome impaction: A computed tomography and cadaveric study

This study aimed to determine the optimal location of the iliac cortical window (ICW) for the direct reduction of acetabular dome impactions using a reference bony landmark. MethodsIn the first part of the study, computed tomography scans of 10 normal acetabula, the femoral head weight bearing area, were projected through the superior iliac cortical surface perpendicular to the plane of the true pelvis to show the area that corresponds to the acetabular dome. A line connecting each pair of anterior inferior iliac spines (AIIS) was drawn then reflected in the superior surface of the acetabulum and a reference point (RP) was marked on the line halfway between the AIIS and the pelvic brim. A 12-point 1-cm interval grid with horizontal and vertical axes labeled A, B, C and 1 to 4, respectively, overlying the acetabular surface projection was created to identify the location of the acetabular dome. In the second part of the study, the 12-point grid was marked on eight fresh cadavers (16 acetabula) and the same acetabular dome reference point was identified. K-wires were drilled into the acetabula using a parallel drill guide at each of the twelve grid points. An arthrotomy was carried out and the locations of the K-wires which penetrated the acetabular dome were recorded. ResultsThe average distance from the AIIS to the medial pelvic brim in the CT scans and cadaveric study were 47.7 and 45.9 mm, respectively. The K-wires at grid points B2 and C1 had a 100% correlation to the dome area. The A2, B1, and C2 grid points had a correlation with the dome area of >80%. The remaining grid points had joint penetrations ranging from 6.25% to 62.5%. ConclusionThe proposed RP, which can be easily identified intraoperatively, and the area 1 cm2 around the RP (except in the posterior direction) can be used as reliable reference landmarks and for identification of the location of the ICW for the reduction of an acetabular dome impaction.

A retrospective CT based comparative analysis of available screw pathways to determine optimal iliac screw trajectory

<b>Introduction:</b> The lumbo-sacral stabilization using iliac screw is gaining popularity in such cases of long multi segment lumbar constructs. Iliac screws help to achieve strong spinopelvic fixation, augments and protects sacral screws. However, there is a great variability found in literature for iliac screw fixation in terms of trajectory, screw length and screw diameter. Also, to the best of our knowledge, there is lacunae in current literature regarding the optimal pathway, screw length and screw diameter in the Indian population. Hence, we planned the study with the aim to analyze the available screw pathways to determine optimal iliac screw trajectory, screw length and diameter for the Indian population.<br /> <b>Material and methods:</b> This was a tertiary center-based retrospective study. One hundred pelvic CT scans of patients in 18-70 years age, who underwent abdominal CT on Siemens 256-slice dual source CT scanner for various indications were evaluated. Subsequently, 4 iliac screw trajectories were assessed by connecting the points given below using double oblique reformats on which the lengths and narrowest zones of these trajectories were measured. Path A: Posterior Superior Iliac Spine (PSIS) to Anterior Superior Iliac Spine (AIIS); Path B: point between PSIS and posterior inferior iliac spine (PIIS) to Anterior Inferior iliac spine  (AIIS); Path C: iliac crest intersection point (CLIC) point to Upper acetabulum; Path D: CLIC point to acetabular center.<br /> [p1] <b>[a2] Results:</b> Statistically significant difference was found in the lengths of various pathways. Path A (PSIS to AIIS) was found to be the longest (mean 13 cm). The second longest path in our study was path C (CLIC point to Upper acetabulum). The narrowest widths of each path were not found to have any statistically significant difference.<br /> <b>Conclusion:</b> Iliac screw fixation is of paramount importance for lumbosacral stabilization. Of the studied paths, trajectory from posterior-superior iliac spine to Antero-inferior iliac spine has the longest passage length and is the most optimal path for the Indian population. In case additional screws are required, the trajectory from CLIC point to Upper acetabulum provides the second largest screw passage.

A radiological analysis of pelvic fixation trajectories: patient series.

Three well-defined methods for pelvic fixation are used for biomechanical support in spine fusion constructs: iliac, recessed iliac, and S2-alar-iliac (S2AI) screws. The authors compared the maximum screw sizes that could be placed with these techniques by using image-guidance software and high-resolution computed tomography scans from 20 randomly selected patients. Six trajectories were plotted per side, beginning at recognized starting points (standard or recessed posterior superior iliac spine [PSIS] or S2AI screw) and ending at the anterior inferior iliac spine (AIIS) or supra-acetabular notch (SAN). The mean maximum screw length and width ranged from 80.0 ± 32.2 mm to 140.8 ± 22.6 mm and from 8.25 ± 1.2 mm to 13.0 ± 2.7 mm, respectively, depending on the trajectory. Statistically significant differences in length were found between the standard and recessed PSIS trajectories to the AIIS (p < 0.001) and between the standard PSIS-to-AIIS trajectory and the S2AI-to-AIIS (p = 0.007) or S2AI-to-SAN (p < 0.001) trajectories. The most successful trajectory was the PSIS to SAN (95%, 38/40). The traditional iliac screw trajectory enabled the longest and widest screw trajectories and highest rate of successful screw placement with the fewest theoretical breaches more reliably than recessed and S2AI trajectories. These findings may help surgeons plan for maximum screw purchase for pelvic fixation.

Better forgotten joint scores when the angle of the prosthetic trochlea is lateral to the quadriceps vector in kinematically aligned total knee arthroplasty.

The primary aim was to analyze unrestricted kinematic alignment (unKA) total knee arthroplasty (TKA) and determine the frequency of medial deviation of the prosthetic trochlear angle (PTA) of the femoral component relative to the quadriceps vector (QV) that terminates at the anterior inferior iliac spine (AIIS), and whether patients with medial deviation had a worse Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) relative to those with lateral deviation. The secondary aim was to determine the frequency of medial deviation for mechanical alignment (MA) TKA simulations. From a database of a single surgeon, the study extracted de-identified data on 147 patients with a CT scanogram showing the pelvis and AIIS, a limb with an unKA TKA, and a native (i.e., healthy) opposite limb. On the scanogram, an examiner, blinded to the PROMs, measured the PTA-QV angle on the unKA TKA and on the opposite limb simulated MA TKA by drawing the PTA at 6° valgus relative to the femoral mechanical axis and measuring the PTA-QV angle. Medial deviation of the PTA occurred in 86% of patients with unKA TKA, and the 126 with medial deviation had a 17/1 point worse median FJS/OKS than the 21 with lateral deviation at a mean follow-up of 47 ± 8 months, respectively (p < 0.0001, p = 0.0053). In addition, 21%, 17%, and 8% of MA TKA had medial deviation after radiographic simulation using reported surgical errors for manual, patient-specific, and robotic instrumentation, respectively. In most patients with unKA TKA and a smaller proportion with MA TKA, a PTA of 6° valgus was medial to the QV, which, by excluding the patient's Q-angle, might alter patellofemoral kinematics like an incorrectly oriented trochleoplasty. The 17-point worse FJS in the patients with an unKA TKA and medial deviation of the PTA suggests the surgical target should be to orient the PTA lateral to the QV. IV.

Analysis and multiple index evaluation of SPO distribution of bone traction needles for pelvic fracture reduction.

For robot-assisted pelvic fracture reduction, at least two bone needles need to be inserted into the ilium of the affected pelvis, and the robot clamping device is connected with the bone needles. The biomechanical properties of the pelvic musculoskeletal tissues are different with the different Spatial Position and Orientation (SPO) of the bone needles. In order to determine the optimal SPO of bone needle pairs, the constraints between the bone needles and the pelvis are analyzed, and the SPO vectors of 150 groups bone needles are obtained by the KNN-hierarchical clustering method; a batch modeling method of bone needles with different SPO is proposed. 150 finite element models of damaged pelvic musculoskeletal tissue with different SPO of bone needles are established and simulated. The stress and strain distribution homogenization of musculoskeletal tissue with bone needles as evaluation index, the simulation results of 150 models are evaluated. Results show that, the anterior superior iliac spine and the anterior inferior iliac spine are suitable regions to place bone needles in the pelvis, and the optimal distribution of the needle combination is found in this region. The overall stress and strain distribution of the damaged pelvic musculoskeletal tissue under the large reduction force is the best.

Lateral Center-edge Angle of 18° (Bone-Edge): Threshold for Hip Arthroscopy Treatment in Patients with Borderline Developmental Dysplasia of the Hip?

Hip arthroscopy for the treatment of symptomatic borderline developmental dysplasia of the hip (BDDH) has been controversial. The purpose of this study was to retrospectively analyze minimum 2-year outcomes of BDDH after arthroscopic surgery and explore the criteria and thresholds of the lateral center-edge angle (LCEA) in arthroscopic surgery for BDDH. Data were retrospectively collected from patients aged 18-50 who underwent arthroscopic surgery for BDDH and had an LCEA 18-25° between September 2016 and June 2020. The consistency of interobserver and intraobserver measurements of bone-edge LCEA was analyzed. Patients were divided into two groups based on LCEA (18-20°and 20-25°) and the results of arthroscopy compared between groups. Patient-reported outcome (PRO) scores, consisting of the modified Harris hip score (mHHS), the visual analogue scale (VAS) and the international hip outcome tool-12 (IHOT-12), the minimal clinically important difference (MCID) and patient acceptable symptom status (PASS) were calculated. In 52 patients with ≥2-year follow-up, female patients accounted for 71.2% and the mean age was 30.8 ± 8.4 years (range: 18 to 49 years). There was a high level of agreement when measuring the bone-edge LCEA definition of BDDH (Kappa = 0.921). Interobserver repeatability (ICC = 0.909, 95%CI: 0.847-0.947) and intraobserver repeatability (ICC = 0.944, 95%CI: 0.905-0.968) were excellent for bone-edge LCEA measurements. In addition to LCEA and Tönnis angle, there were no significant differences in α angle, neck stem angle, femoral anteversion angle, medial joint space, Tönnis grade of osteoarthritis, acetabular retroversion (8 sign), Cam deformity and anterior inferior iliac spine (AIIS) morphology between the two groups (p > 0.05). Intraoperative findings and procedures showed no statistical difference between groups (p > 0.05). The mean follow-up time was 44.4 ± 11.0 months (range: 25 to 64 months). Postoperative VAS, mHHS and IHOT-12 scores in the LCEA 18-20° group and the LCEA 20-25° group were significantly improved compared with those before surgery, and there was no statistically significant difference in the percentage of MCID and PASS (mHHS and iHOT-12) between the groups (p > 0.05). Patients in the LCEA 18-20° group and the LCEA 20-25° group achieved favorable outcomes after arthroscopic surgery. LCEA 18° (bone-edge) should be the threshold for hip arthroscopic surgery in BDDH patients without obvious hip instability.

Assessment of two entry points for S2 alar-iliac screw in a Japanese cohort using three-dimensional computed tomography scan

Lumbosacral fusion supplemented with sacropelvic fusion has recently been increasingly employed for correcting spinal deformity and is associated with lower incidence of pseudarthrosis and implant failure. To date, few studies have evaluated anatomical parameters and technical feasibility between different entry points for S2 alar-iliac screws. To compare anatomical parameters and technical feasibility of two entry points for the S2 alar-iliac screw (S2AIS) in a Japanese cohort using three-dimensional (3D) computed tomography (CT). Retrospective cohort study. Fifteen men and 15 women aged 50-79 years who underwent pelvic CT at our hospital in 2013. Screw length, lateral angulation, caudal angulation, angle range, distance from the entry point to the sacroiliac joint, distance from the S2AIS to the acetabular roof, distance from the S2AIS to the sciatic notch, and insertion difficulty. We used 30 pelvic CT images (15 men and 15 women). We selected two entry points from previous studies: one was 1 mm distal and 1 mm lateral to the S1 dorsal foramen (A group) and the other was the midpoint between the S1 and S2 dorsal foramen (B group). We resliced the plane in which the pelvis was sectioned obliquely from these entry points to the anterior inferior iliac spine in the sagittal plane. We placed the shortest and longest virtual S2AISs bilaterally in this plane using a 4-mm margin. We measured screw length, lateral angulation, caudal angulation, angle range, distance from the entry point to the sacroiliac joint, distance from the S2AIS to the acetabular roof, distance from the S2AIS to the sciatic notch, and insertion difficulty. These measurements were compared between Groups A and B. In group A, the angle in the sagittal plane was significantly smaller and the distance from the entry point to the sciatic notch was significantly longer than in group B. Group B demonstrated a significantly longer screw length, longer distance from the entry point to the sacroiliac joint, and longer distance from the entry point to the acetabular roof than group A. The rate of insertion difficulty of S2AIS was much higher in group A. Insertion of S2AIS from the midpoint between the S1 and S2 dorsal foramen compared with the entry at distal and lateral to S1 foramen enables insertion of longer screws with low insertion difficulty.

Guidance for dysmorphic sacrum fixation with upper sacroiliac screw based on imaging anatomy study: techniques and indications

ObjectiveThis study aimed to investigate the techniques and indications of upper sacroiliac screw fixation for the dysmorphic sacrum.MethodsThe dysmorphic sacra were selected from 267 three-dimensional pelvic models. The dysmorphic sacra which couldn’t accommodate a 7.3 mm upper trans ilio-sacroiliac screw were classified as the main dysmorphic sacra. Then, the size of the bone corridor, the length of the screw in the corridor, and the orientation of the screw were measured. The insertion point on the sacrum was identified by two bone landmarks.Resultstotally, 30.3% of sacra were identified as the main dysmorphic sacra. The inclinations of the screw oriented from posterior to anterior were (21.80 ± 3.56)° for males and (19.97 ± 3.02)° for females (p < 0.001), and from caudal to cranial were (29.97 ± 5.38)° for males and (28.15 ± 6.21)° for females (p = 0.047). The min diameters of the corridor were (16.31 ± 2.40) mm for males and (15.07 ± 1.58) mm for females (p < 0.001). The lengths of the screw in the Denis III zone were (14.41 ± 4.40) mm for males and (14.09 ± 5.04) mm for females (p = 0.665), and in the Denis II+III zones were (36.25 ± 3.40) mm for males and (38.04 ± 4.60) mm for females (p = 0.005). The rates of LP-PSIS/LAIIS-PSIS were (0.36 ± 0.04) for males and (0.32 ± 0.03) for females (t = 4.943, p < 0.001). The lengths of LPM were (8.81 ± 5.88) for males and (-4.13 ± 6.33) for females (t = 13.434, p < 0.001).ConclusionWhen the sacrum has the features of “sacrum not recessed” and/or “acute alar slope”, the conventional trans ilio-sacroiliac screw couldn’t be placed safely. The inclination oriented from posterior to anterior and from caudal to cranial are approximately 20° and 30°, respectively. The bone insertion point locates in the rear third of the anterior inferior iliac spine to the posterior superior iliac spine. The sacroiliac screw is not recommended to fix the fractures in Denis III zone.

Gluteal Muscle Size and Quality in Professional Ballet Dancers Compared to Non-Dancing Athletes.

Professional ballet dancers load their hips in extreme ranges of motion and commonly report hip pain. Evaluating gluteal muscle size and quality may help guide exercise programs. Objectives of this study were to compare gluteal muscle size and quality (fatty infiltration) in ballet dancers compared to athletes; and to investigate the relationship between gluteal muscle size and quality, and reports of hip-related pain. This study was a case-control design. Professional ballet dancers (current and retired, n = 49, mean age 35 years, range 19-63) and age and sex-matched athletes (current and retired, n = 49) underwent magnetic resonance imaging of both hips. Muscle cross-sectional areas (CSA) were obtained at standardized landmarks for gluteus maximus (GMax) and gluteus medius (GMed). Full muscle volume was calculated for gluteus minimus (GMin). Fatty infiltration was rated using the Goutallier classification system. Muscle size was compared between groups using linear mixed models. Fatty infiltration was compared using a mixed model binary logistic regression. Hip-related pain, participation status, limb side and sex were included as covariates. Ballet dancers had significantly larger GMax (upper P < .01, middle P < .01, lower P = .01) and GMed (level of anterior inferior iliac spine P < .01, greater sciatic foramen P < .01) CSA and larger GMin volume (P < .01), when normalized to weight. There was no difference in fatty infiltration ratings between dancers and non-dancing athletes. Retired dancers and athletes reporting hip-related pain were more likely to have fatty infiltration in GMax lower (P = .04). Gluteal muscles are larger in ballet dancers compared to athletes suggesting high-level loading of these muscles. There is no relationship between hip-related pain and gluteal muscle size. Dancers and athletes have comparable muscle quality.

Ultrasound Assessment of Hip Subspine Bone Morphology Soft-tissue Correlates with Clinical Diagnosis of Impingement

To determine the ultrasound imaging manifestations associated with subspine impingement (SSI), including the osseous and soft-tissue injuries adjacent to anterior inferior iliac spine (AIIS) and to investigate the diagnostic value of ultrasound for SSI. We retrospectively evaluated patients who attended the sports medicine department of our hospital and underwent arthroscopic treatment for femoroacetabular impingement (FAI) between September 2019 and October 2020, with preoperative hip joint ultrasound and computed tomography (CT) examination within 1 month before surgery. All of the FAI patients were divided into the SSI group and non-SSI group, according to the clinical and intraoperative findings. The preoperative ultrasound and CT findings were assessed. The sensitivity, specificity, and positive predictive value (PPV) of some indicators were calculated and compared. Multivariable logistic regression and receiver operating characteristic curve (ROC) were also used. A total of 71 hips were included, with a mean age of 35.4 ± 10.4 years, 56.3% were women. Of these, 40 hips had clinically confirmed SSI. The bone morphology type III, heterogeneous hypoecho in anterosuperior joint capsule and the direct head of rectus femoris (dRF) tendon adjacent to AIIS on the Standard Section of the dRF in ultrasound were associated with SSI. Among them, the heterogeneous hypoecho in the anterosuperior joint capsule had the best diagnostic value for the SSI (85.0% sensitivity, 58.1% specificity, AUC= 0.681). The AUC of the ultrasound composite indicators was 0.750. The AUC and PPV of CT low-lying AIIS for the SSI diagnosis was 0.733 and 71.7%, which could be improved when CT was combined with the ultrasound composite indicators with AUC= 0.831 and PPV= 85.7%. Bone morphology abnormalities and soft-tissue injuries adjacent to the AIIS through sonographic evaluation were associated with SSI. Ultrasound could be used as a feasible method to predict SSI. The diagnostic value for SSI could be improved when ultrasound is combined with CT. Level IV, case series.

Targeting of Periprosthetic Muscles for the Ultrasonographic Screening of Hip Abnormalities in Hip Resurfacing Arthroplasty Patients.

Hip resurfacing arthroplasty (HRA) patients require subsequent annual screening for postoperative complications. Ultrasonography may be useful for this purpose but lacks a screening protocol for hips. The purpose of this study was to evaluate the accuracy of ultrasonography for detecting postoperative complications in HRA patients using a screening protocol that specifically targets periprosthetic muscles. We enrolled 45 hips from 40 HRA patients with a mean follow-up period of 8.2 years. MRI and ultrasonography scans were simultaneously conducted at follow-up. The ultrasonography assessments were conducted on the anterior part of the hip that targets iliopsoas, sartorius, rectus femoris, lateral with anterior superior and inferior iliac spine (ASIS and AIIS) as bony landmarks, and the lateral and posterior parts that target fascia tensor, short rotators, and gluteus minimus, medius, and maximus with greater trochanter and ischial tuberosity as bony landmarks. The accuracy of diagnosing postoperative abnormalities and the visibility of periprosthetic muscles were compared between these two modalities. Both MRI and ultrasonography detected an abnormal region in eight cases comprising two infections, two pseudotumors, and four patients with greater trochanteric bursitis. Among these cases, four hips required implant removal. The increase in anterior space, measured as the distance between the iliopsoas and resurfacing head, was a good indicator for the abnormal mass in these four HRA cases. In the assessment of periprosthetic muscles, MRI showed a much lower visibility than ultrasonography in the iliopsoas (6.7% vs. 100%), gluteus minimus (6.7% vs. 88.9%), and short rotators (8.8% vs. 71.4%) due to implant halation. By targeting periprosthetic muscles, ultrasonography can detect postoperative complications as effectively as MRI assessments in HRA patients. Ultrasonography has superior visibility in the periprosthetic muscles of HRA patients, indicating its utility for the screening of small legions in these cases which may not be visible by MRI.

Cadaveric study investigating the femoral nerve-sparing volume for pericapsular nerve group (PENG) block

BackgroundThis cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90) required to stain the iliac bone between the anterior inferior iliac spine (AIIS) and the...