Low Back Pain Improves After Surgery for Lesser Trochanteric-Ischial Impingement.

PURPOSE: To assess the effects of surgery for lesser trochanteric-ischial impingement (LTI) on low back pain. METHODS: The records of patients with LTI who underwent endoscopic partial resection of the lesser trochanter (LT) between May of 2017 and February of 2019 were reviewed. Inclusion criteria were the presence of low back pain in association with hip pain, diagnosis of LTI, and partial resection of the LT to treat LTI. Exclusion criteria were less than 12 months of postoperative follow-up and hip or spine surgery after the LTI surgery. Patients were assessed before surgery and at the most recent follow-up with the modified Harris Hip Score and Oswestry Disability Index for lumbar spine. RESULTS: Thirty patients (31 hips) met the inclusion criteria. Four patients were lost to follow-up. Two patients with borderline dysplasia and grade 1 and 2 osteoarthritis underwent total hip arthroplasty after the partial resection of the LT. The results are presented considering the remaining 24 patients (25 hips). The average age at surgery was 51 years (range 32-65 years). The mean follow-up after the surgery for LTI was 19 months (range 12-35 months). The mean ± SD ODI improved from 48% ± 15 before the LTI surgery to 21% ± 22 (P < .001) at the most recent follow-up. Improvement in the Oswestry Disability Index above the minimal clinical important difference was observed in 16 patients (67%) following the LTI surgery. The mean ± SD modified Harris Hip Score improved from 55.8 ± 14 before LTI surgery to 81.3 ± 14.3 (P < .001). CONCLUSIONS: Decrease in low back pain above the minimal clinically important difference is observed in 2 of 3 patients after partial resection of the LT. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Femoral Derotation Osteotomy Improves Hip and Spine Function in Patients With Increased or Decreased Femoral Torsion.

PURPOSE: To evaluate the outcomes of proximal femoral derotation osteotomy (PFDO) on the hip and spine function of patients with abnormal femoral torsion. METHODS: This retrospective study included patients who underwent PFDO to treat increased or decreased femoral torsion between July 2014 and February 2019. The exclusion criteria were: previous fracture, fixation of slipped capital femoral epiphysis or osteotomy in the ipsilateral femur; PFDO associated to varus or valgus osteotomy; Tönnis grade 2 or 3 osteoarthritis; and PFDO performed to treat knee abnormalities. Hip function was assessed through the modified Harris Hip Score (mHHS). A subgroup of consecutive patients with low back pain before the PFDO and operated after 2017 had the spine function assessed through the Oswestry disability index (ODI). RESULTS: A total of 37 hips (34 patients) were studied: 15 hips with increased femoral torsion and 22 with decreased femoral torsion. Eight patients were male and 26 were female. The average age at PFDO was 33 years (range, 15-54 years). At a mean follow-up of 24 months (range, 12-65 months), the mean mHHS improved from 58.1 ± 14.3 before PFDO to 82 ± 15.6 at the most recent follow-up (P < .001). Improvement in the mHHS above the minimum clinically important difference (MCID) was observed in 33 hips (89%). In the subgroup of 14 consecutive patients with ODI available, the ODI improved from a mean of 45% ± 16% before the PFDO to 22% ± 17% at the most recent follow-up (P = .001). Nine (64.3%) of the 14 patients presented improvement in the ODI above the MCID. Revision procedure with a larger intramedullary nail was necessary in 2 hips to treat nonunion. CONCLUSION: Proximal femoral derotation osteotomy improves the hip and spine function in patients with increased or decreased femoral torsion and nonarthritic hips. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Deep gluteal syndrome is defined as a non-discogenic sciatic nerve disorder with entrapment in the deep gluteal space: a systematic review.

PURPOSE: Clinicians are not confident in diagnosing deep gluteal syndrome (DGS) because of the ambiguity of the DGS disease definition and DGS diagnostic pathway. The purpose of this systematic review was to identify the DGS disease definition, and also to define a general DGS diagnostic pathway. METHODS: A systematic search was performed using four electronic databases: PubMed, MEDLINE, EMBASE, and Google Scholar. In eligibility criteria, studies in which cases were explicitly diagnosed with DGS were included, whereas review articles and commentary papers were excluded. Data are presented descriptively. RESULTS: The initial literature search yielded 359 articles, of which 14 studies met the eligibility criteria, pooling 853 patients with clinically diagnosed with DGS. In this review, it was discovered that the DGS disease definition was composed of three parts: (1) non-discogenic, (2) sciatic nerve disorder, and (3) nerve entrapment in the deep gluteal space. In the diagnosis of DGS, we found five diagnostic procedures: (1) history taking, (2) physical examination, (3) imaging tests, (4) response-to-injection, and (5) nerve-specific tests (electromyography). History taking (e.g. posterior hip pain, radicular pain, and difficulty sitting for 30 min), physical examination (e.g. tenderness in deep gluteal space, pertinent positive results with seated piriformis test, and positive Pace sign), and imaging tests (e.g. pelvic radiographs, spine and pelvic magnetic resonance imaging (MRI)) were generally performed in cases clinically diagnosed with DGS. CONCLUSION: Existing literature suggests the DGS disease definition as being a non-discogenic sciatic nerve disorder with entrapment in the deep gluteal space. Also, the general diagnostic pathway for DGS was composed of history taking (posterior hip pain, radicular pain, and difficulty sitting for 30 min), physical examination (tenderness in deep gluteal space, positive seated piriformis test, and positive Pace sign), and imaging tests (pelvic radiographs, pelvic MRI, and spine MRI). This review helps clinicians diagnose DGS with more confidence. LEVEL OF EVIDENCE: IV.

Editorial Commentary: Hip Labral Revision Reconstruction in a Fellowship Training Center: A Report From the Mountains.

Hip labral reconstruction has proven to be a successful technique in restoring normal labrum function. However, sometimes revision surgery is required. A recent, well-designed prospective study provides significant support for revision labral reconstruction, showing how it leads to improved hip mechanics and reduction in pain. The success of the study design and this report is a testament to an educational institution dedicated to fellowship training.

Accuracy of 3 Clinical Tests to Diagnose Proximal Hamstrings Tears With and Without Sciatic Nerve Involvement in Patients With Posterior Hip Pain.

PURPOSE: To determine the diagnostic accuracy of the active hamstring test at 30° (A-30) and 90° (A-90) of knee flexion, the long stride heel strike (LSHS) test, and combination of the 3 tests for individuals with hamstring tendon tears, with and without sciatic nerve involvement. METHODS: A retrospective review of 564 consecutive clinical records identified 42 subjects with a mean age of 50.31 ± 15 years who underwent a standard physical examination prior to magnetic resonance imaging (MRI) evaluation and diagnostic injection for posterior hip. The physical examination included the A-30, A-90, and LSHS tests. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were calculated to determine the diagnostic accuracy of these 3 tests. RESULTS: Forty-two subjects (female = 32 and male = 10) with a mean age of 50.31 years (range 15-77, ± SD 14.52) met the inclusion criteria and were included in the review. Based on MRI and/or injection, 64.28% (27/42) of subjects were diagnosed with hamstring tear. Fourteen (51.85%) presented with sciatic nerve involvement. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio for each test were as follows: A-30 knee flexion: 0.73, 0.97, 23.43, 0.28, and 84.73; A-90 knee flexion: 0.62, 0.97, 20.00, 0.39, and 51.67; LSHS: 0.55, 0.73, 2.08, 0.61, and 3.44. The most accurate findings were obtained when the results of the A-30 and A-90 were combined, with sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of 0.84, 0.97, 26.86, 0.17, and 161.89, respectively. CONCLUSION: The combination of the active hamstring A-30 and A-90 tests proved to be a highly accurate and valuable tool to diagnose proximal hamstring tendons tears with or without sciatic nerve involvement in subjects presenting with posterior hip pain. LEVEL OF EVIDENCE: Level III, diagnostic study.

Incorporating Hip Arthroscopy Into A Practice.

Hip arthroscopy is one of the most rapidly growing areas in orthopaedic surgery because of increased awareness of nonarthritic hip pathologies, advanced imaging modalities, and advanced techniques to reproducibly manage nonarthritic hip pathologies within a deep soft-tissue envelope and a constrained joint. In addition, more academic medical centers are providing residents with education on hip arthroscopy, and many hip preservation fellowships and courses are helping increase awareness of nonarthritic hip pathologies. Nonarthritic hip pathologies currently managed via hip arthroscopy include nonrepairable labral lesions, femoroacetabular impingement, hip instability, and hip fractures. Periarticular hip pathologies currently managed via endoscopy include greater trochanteric pain syndrome, tendinopathy and tears of the gluteus medius and minimus, partial and complete hamstring avulsions, and sciatic nerve entrapment. Ischiofemoral impingement may be addressed endoscopically via the deep gluteal space. Orthopaedic surgeons should understand the role and safety of hip arthroscopy in the pediatric population, specifically in the management of slipped capital femoral epiphysis, Legg-Calvé-Perthes disease, and septic arthritis of the hip. The efficacy of hip arthroscopy is limited, and hip arthroscopy is relatively contraindicated in patients with osteoarthritis and hip dysplasia. Complications can occur and likely are underreported in patients who undergo hip arthroscopy. Orthopaedic surgeons should understand practical issues associated with incorporating hip arthroscopy into a practice, including the difficult learning curve associated with hip arthroscopy and the reluctance of some payors to reimburse procedures performed arthroscopically because hip arthroscopy is a relatively new technology.

Editorial Commentary: Pioneering the Gluteal Interval: Understanding and Treating Undersurface and Full-Thickness Gluteus Medius Tears of the Hip.

Lateral-based hip disease is severely impairing for many patients. Treatment decision making requires a thorough understanding of the biomechanical and clinical interpretation of the physical examination. The outcomes of these under-recognized pathologies are explained with success. A recent study has described the diagnostic and surgical treatment outcomes of this impairing condition of partial and full-thickness gluteus medius tears.

Preemptive Analgesia in Hip Arthroscopy: A Randomized Controlled Trial of Preemptive Periacetabular or Intra-articular Bupivacaine in Addition to Postoperative Intra-articular Bupivacaine.

PURPOSE: To evaluate and compare the efficacy of intra-articular and periacetabular blocks for postoperative pain control after hip arthroscopy. METHODS: Forty-two consecutive patients scheduled for hip arthroscopy were randomized into 2 postoperative pain control groups. One group received preemptive intra-articular 20 mL of bupivacaine 0.5% injection, and the second group received preemptive periacetabular 20 mL of bupivacaine 0.5% injection. Before closure all patients received an additional dose of 20 mL of bupivacaine 0.5% intra-articularly. Data were compared with respect to postoperative pain with visual analog scale (VAS) and analgesic consumption, documented in a pain diary for 2 weeks after surgery. RESULTS: Twenty-one patients were treated with intra-articular injection, and 21 patients with peri-acetabular injection. There were no significant differences with regards to patient demographics or surgical procedures. VAS scores recorded during the first 30 minutes postoperatively and 18 hours after surgery were significantly lower in the periacetabular group compared with in the intra-articular group (0.667 ± 1.49 vs 2.11 ± 2.29; P < .045 and 2.62 ± 2.2 vs 4.79 ± 2.6; P < .009). There were no differences between the groups with regard to analgesic consumption. CONCLUSIONS: Periacetabular injection of bupivacaine 0.5% was superior to intra-articular injection in pain reduction after hip arthroscopy at 30 minutes and 18 hours postoperatively. However, total analgesic consumption over the first 2 postoperative weeks and VAS pain measurements were not significantly affected. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Editorial Commentary: Arthroscopic Hip Preservation Is Critical for Preserving Health and Function in Adolescents and Adults.

Hip health is a critical factor in preserving daily life activities and wellbeing for both adults and adolescents. There are several potential economic influences in developing arthroscopic hip techniques for the evaluation and treatment of hip pathology in patients of all ages.

Femoral Neck Anteversion and Lesser Trochanteric Retroversion in Patients With Ischiofemoral Impingement: A Case-Control Magnetic Resonance Imaging Study.

PURPOSE: To assess the relationship between the femoral neck version (FNV) and lesser trochanteric version (LTV) in symptomatic patients with ischiofemoral impingement (IFI) as compared with asymptomatic hips. METHODS: The FNV and LTV of patients with symptomatic IFI who underwent magnetic resonance imaging assessment including a standardized femoral version study protocol were compared with those of patients with asymptomatic hips in this retrospective, observational study. Patients with isolated intra-articular pathology, prior hip fracture, and lesser trochanter deformity were excluded. The FNV, LTV, ischiofemoral space, and quadratus femoris space were evaluated on axial magnetic resonance imaging, as well as the angle between the LTV and the FNV. Independent t-tests were used to determine differences between groups. RESULTS: Data from 11 out 15 symptomatic patients and 250 out of 320 asymptomatic patients were analyzed. The mean ischiofemoral space (11.9 v 22.9 mm; P < .001; 95% confidence interval [CI], 6.9 to 15.2) and mean quadratus femoris space (7.2 mm v 14.9 mm; P < .001; 95% CI, 5.4 to 8.6) were significantly smaller in symptomatic patients versus asymptomatic patients. There was no difference in mean LTV between groups (-23.6° v -24.2°; P = .8; 95% CI, -7.5 to 6.4), however, the mean FNV (21.7° v 14.1°; P = .02; 95% CI, -14.2 to -1.1) and the angle between the FNV and LTV on average (45.4° v 38.3°; P = .01; 95% CI, -12.9 to -1.3) were higher in symptomatic than in asymptomatic patients, with statistical significance. CONCLUSIONS: The femoral mean neck anteversion and the mean angle between the FNV and LTV are significantly higher in patients with symptomatic IFI. The mean LTV is not increased in patients with symptomatic ischiofemoral impingement as compared with those patients with asymptomatic hips. LEVEL OF EVIDENCE: Level III, diagnostic study.

Accuracy of 2 Clinical Tests for Ischiofemoral Impingement in Patients With Posterior Hip Pain and Endoscopically Confirmed Diagnosis.

PURPOSE: To establish the accuracy of the long-stride walking (LSW) and ischiofemoral impingement (IFI) tests for diagnosing IFI in patients whose primary symptom is posterior hip pain. METHODS: Confirmed IFI cases and cases in which IFI had been ruled out were identified considering imaging, injections, and endoscopic assessment, combined with pain relief and negative IFI-specific tests after treatment. Demographic data, duration of symptoms, pain location, ischiofemoral space, quadratus femoris space, quadratus femoris edema, surgical findings, and visual analog scale score for pain before and after treatment were computed for all patients included in this study. Sensitivity, specificity, predictive values, likelihood ratios, and diagnostic odds ratios were computed individually for the LSW test and IFI test. RESULTS: Cases from 1,166 consecutive hip operations and charts from 564 consecutive outpatients were retrospectively reviewed to identify patients who underwent injection and/or endoscopic surgery because of posterior hip pain. Thirty individuals (21 women and 9 men) with a mean age of 49.8 years (range, 20 to 76 years; standard deviation, 13.0 years) were included for analysis. Of the 30 patients, 17 (56.6%) were confirmed as positive for IFI and 13 (43.4%) were confirmed as negative for IFI. The IFI test had a sensitivity of 0.82, specificity of 0.85, positive predictive value of 0.88, negative predictive value of 0.79, positive likelihood ratio of 5.35, negative likelihood ratio of 0.21, and diagnostic odds ratio of 25.6. The LSW test had a sensitivity of 0.94, specificity of 0.85, positive predictive value of 0.89, negative predictive value of 0.92, positive likelihood ratio of 6.12, negative likelihood ratio of 0.07, and diagnostic odds ratio of 88.8. CONCLUSIONS: In patients with complaints of posterior hip pain and negative evaluation findings for lumbosacral spine involvement or static/dynamic mechanical axis malalignment, the IFI and LSW tests are highly accurate to help identify those with or without IFI. LEVEL OF EVIDENCE: Level III, diagnostic study.

Pathological findings in patients with low anterior inferior iliac spine impingement.

PURPOSE: Femoroacetabular impingement (FAI) has been well described in recent years as one of the major causes of hip pain potentially leading to acetabular labral tears and cartilage damage, which may in turn lead to the development of early degenerative changes. More recently, extra-articular patterns of impingement such as the anterior inferior iliac spine (AIIS)/subspine hip impingement have gained focus as a cause of hip pain and limitation in terminal hip flexion and internal rotation. The purpose of this study was to evaluate the prevalence of low AIIS in patients undergoing hip arthroscopy and to characterize the concomitant intra-articular lesions. METHODS: Between November 2011 and April 2013, 100 consecutive patients underwent hip arthroscopy for various diagnoses by a single surgeon. After intra-operative diagnosis of low AIIS was made, a comprehensive review of the patients' records, preoperative radiographs, and intra-operative findings was conducted to document the existence and location of labral and chondral lesions. RESULTS: Twenty-one (21 %) patients had low AIIS. There were 13 males (mean age 38.4 years) and eight females (mean age 35.5 years). Eight patients had pre-operative radiographic evidence of low AIIS. All patients had a labral tear anteriorly, at the level of the AIIS; 17 had chondrolabral disruption and 17 had chondral lesions in zone two (antero-superior); and four patients had lesion in zones two and three. CONCLUSIONS: Low AIIS is a common intra-operative finding in hip arthroscopy patients. Characteristic labral and chondral lesions are routinely found in a predictable location that effaces the low AIIS. Level of Evidence-Level IV, Case Series.

Diagnosis and 2-year outcomes of endoscopic treatment for ischiofemoral impingement.

PURPOSE: The purposes of this study were to investigate the clinical and radiographic presentation of patients with ischiofemoral impingement (IFI) and to assess the outcomes of endoscopic treatment with partial resection of the lesser trochanter. METHODS: Five patients with IFI who underwent endoscopic treatment with partial resection of the lesser trochanter were retrospectively reviewed. The outcomes were assessed at a mean follow-up of 2.3 years (range, 2 to 2.5 years) through the modified Harris Hip Score and a visual analog scale score for pain. Physical examination tests provoking the impingement between the lesser trochanter and ischium were used for the diagnosis of IFI, including the IFI test and reproducible pain lateral to the ischium with the long-stride walking test. The presence of quadratus femoris muscle edema and a decreased ischiofemoral space on magnetic resonance imaging was also necessary for the diagnosis. RESULTS: The mean modified Harris Hip Score increased from 51.3 points (range, 34.1 to 73.7 points) preoperatively to 94.2 points (range, 78.1 to 100 points) at the final follow-up (P = .003). The mean visual analog scale score for pain decreased from 6.6 (range, 6 to 7.3) before surgery to 1 (range, 0 to 4) at the final follow-up (P = .001). The mean duration to return to sport after surgery was 4.4 months (range, 1 to 7 months) for the 5 patients in this study. No complication was observed. CONCLUSIONS: The endoscopic treatment of IFI was effective at 2 years in 5 patients with consistent clinical and imaging diagnostic findings. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Monopolar radiofrequency use in deep gluteal space endoscopy: sciatic nerve safety and fluid temperature.

PURPOSE: The purpose of this study was to evaluate the temperature at the sciatic nerve when using a monopolar radiofrequency (RF) probe to control bleeding in deep gluteal space endoscopy, as well as assess the fluid temperature profile. METHODS: Ten hips in 5 fresh-frozen human cadaveric specimens from the abdomen to the toes were used for this experiment. Temperatures were measured at the sciatic nerve after 2, 5, and 10 seconds of continuous RF probe activation over an adjacent vessel, a branch of the inferior gluteal artery. Fluid temperatures were then measured at different distances from the probe (3, 5, and 10 mm) after 2, 5, and 10 seconds of continuous probe activation. All tests were performed with irrigation fluid flow at 60 mm Hg allowing outflow. RESULTS: After 2, 5, or 10 seconds of activation over the crossing branch of the inferior gluteal artery, the mean temperature increased by less than 1°C on the surface and in the perineurium of the sciatic nerve. Considering the fluid temperature profile in the deep gluteal space, the distance and duration of activation influenced temperature (P < .05). Continuous delivery of RF energy for 10 seconds caused fluid temperature increases of 1.2°C, 2°C, and 3.1°C on average at 10 mm, 5 mm, and 3 mm of distance, respectively. CONCLUSIONS: This study found the tested monopolar RF device to be safe during use in vessels around the sciatic nerve after 2, 5, and 10 seconds of continuous activation. The maximum fluid temperature (28°C) after 10 seconds of activation at 3 mm of distance is lower than the minimal reported temperature necessary to cause nerve changes (40°C to 45°C). CLINICAL RELEVANCE: Monopolar RF seems to be safe to the neural structures when used at more than 3 mm of distance and with less than 10 seconds of continuous activation in deep gluteal space endoscopy with fluid inflow and outflow.

Anterior Electronic Hip Pain Drawings Are Helpful for Diagnosis of Intra-articular Sources of Pain: Lateral or Posterior Drawings Are Unreliable.

Purpose: The purpose of this study was to determine the accuracy of electronic hip pain drawing to diagnose intra-articular source of pain in nonarthritic hips, defined by response to an intra-articular injection. Methods: A retrospective assessment was performed in consecutive patients who had an intra-articular injection completed within a 1-year period. Patients were classified as responders or nonresponders to intra-articular hip injection. A positive injection was defined as greater than 50% hip pain relief within 2 hours after injection. Electronic pain drawings collected before injection were then evaluated according to the hip region marked by the patients. Results: Eighty-three patients were studied after applying inclusion and exclusion criteria. Anterior hip pain on drawing had a sensitivity of 0.69, specificity of 0.68, positive predictive value (PPV) of 0.86, and negative predictive value (NPV) of 0.44 for intraarticular source of pain. Posterior hip pain on drawing had a sensitivity of 0.59, specificity of 0.23, PPV of 0.68, and NPV of 0.17 for intra-articular source of pain. Lateral hip pain on drawing had a sensitivity of 0.62, specificity of 0.50, PPV of 0.78, and NPV of 0.32 for intraarticular source of pain. Conclusion: Anterior hip pain on electronic drawing has a sensitivity of 0.69 and specificity of 0.68 for intra-articular source of pain in nonarthritic hips. Lateral and posterior hip pain on electronic pain drawings are not reliable to rule out intra-articular hip disease. Level of Evidence: Level III, case-control study.

Imaging changes following surgery for ischiofemoral impingement.

Partial resection of the lesser trochanter (LT plasty) has been increasingly recommended to treat ischiofemoral impingement. However, there is a lack of studies on the imaging findings following LT plasty. The purpose of this study was to assess magnetic resonance imaging (MRI) changes on the lesser trochanter and surrounding musculotendinous structures following LT plasty to treat ischiofemoral impingement. Twenty-one patients (21 hips) were studied. The LT length and cross-sectional area of the iliopsoas muscle were measured on MRI before and after surgery. The MRIs were performed on average 11 months (range, 3 to 25 months) after surgery. The mean ± standard deviation amount of LT resected (difference between pre- and postoperative LT length) was 7.3 mm ± 2.5 mm. The iliopsoas cross-sectional area decreased after the LT plasty in 95% of the hips (20/21) by an average of 35% ± 16%. The reduction in iliopsoas size had no significant correlation with improvement on the modified Harris Hip Score at a mean follow-up of 17 months after surgery (r = -0.13, P = 0.58). The iliopsoas muscle size decreased on average 35% following endoscopic LT plasty. The decrease was not correlated with midterm functional outcomes.

Hip physical examination extension loss and radiographic osseous findings in patients with low back pain and nonarthritic hips.

The association between hip and spine abnormalities is frequent, and limitation in hip extension has been linked with low back pain. The purpose of this study was to assess the radiographic osseous findings in nonarthritic hips of patients with hip pain, low back pain, and limited hip extension. Ninety patients (92 hips) were included in this study. Hip extension was tested in the contralateral decubitus position with the hip in neutral abduction/adduction and neutral rotation. In sequence, hip extension was tested by adding passive abduction, followed by internal/external rotation of the hip. A hip extension limitation was defined as less than zero degrees of extension. Imaging studies were assessed for the following osseous morphologies: decreased ischiofemoral space (≤17 mm), increased femoral torsion (≥30°), decreased femoral torsion (≤5°), and posterior acetabular overcoverage. Fifty-seven out of 92 hips (62%) had at least one osseous imaging finding for limitation in hip extension: decreased ischiofemoral space (38/92, 41%), increased femoral torsion (5/92, 5%), decreased femoral torsion (24/92, 26%), and posterior acetabular overcoverage (21/92, 23%). Decreased ischiofemoral space, femoral torsional abnormalities, and/or posterior acetabular wall overcoverage are observed in imaging studies of most individuals with limitation of hip extension and low back pain.

Usefulness of magnetic resonance imaging to diagnose greater trochanteric-ischial impingement.

Extra-articular impingement between the femur and ischium is increasingly recognized as a cause of hip pain. The purpose of this study was to assess the diagnostic parameters for greater trochanteric-ischial impingement (GTI) in magnetic resonance imaging (MRI) studies. Seven patients (seven hips) diagnosed with GTI were retrospectively identified. For each of these seven patients, three controls were matched by gender, height, and weight to create a control group of 21 asymptomatic hips. The same technique and positioning were utilized to acquire the MRIs in the GTI and control groups. The MRI was performed with the lower limbs in a functional position reproducing the midstance phase of the gait cycle. The greater trochanteric-ischial distance was measured in the axial cut showing the shortest distance between the greater trochanter and the ischial tuberosity. The mean greater trochanteric-ischial distance was 26.2 mm in the GTI group and 33.8 mm in the control group (P < 0.01). Greater trochanteric-ischial distance ≤28 mm had a sensitivity of 86% and specificity of 86% in identifying GTI. In conclusion, utilizing MRI with functional positioning of the lower limbs, greater trochanter-ischial distance ≤28 mm is helpful to diagnose GTI in women.

Snapping of the Sciatic Nerve and Sciatica Provoked by Impingement Between the Greater Trochanter and Ischium: A Case Report.

CASE: A 64-year-old woman developed worsening sciatica associated with snapping at the hip over a period of 4 years. The physical examination and dynamic ultrasound revealed the snapping of the sciatic nerve (SN) provoked by impingement between the greater trochanter (GT) and the ischium. Additional imaging studies demonstrated hyperintense signal in the SN at the hip, sagittal imbalance, decreased ischiofemoral space, and increased femoral torsion. CONCLUSION: Snapping and entrapment of the SN provoked by impingement between the GT and the ischium should be considered in the differential diagnosis of snapping hip and/or sciatica.