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

Femoral anteversion change is associated with ischiofemoral impingement after total hip arthroplasty: a retrospective CT evaluation

OBJECTIVES

We evaluated the relationship between femoral anteversion (FA), FA change, and ischiofemoral impingement (IFI) and the relationship between FA, femoral offset (FO), and greater trochanteric pain syndrome (GTPS) after total hip arthroplasty (THA).

MATERIALS AND METHODS

In this retrospective study, two readers assessed FA and FO on CT images of 197 patients following primary THA with an anterior surgical approach between 2014 and 2021. FA change was calculated relative to preoperative CT, while FO change was calculated relative to preoperative radiographs and classified as decreased (≥-5 mm), increased (≥ + 5 mm), or restored (± 5 mm). Clinical and imaging data were analyzed for IFI and GTPS after surgery. Group differences were evaluated using Student's t-test, chi-square analysis, and receiver operating characteristic (ROC) analysis.

RESULTS

The change in FA was 3.6 ± 3.3° to a postoperative FA of 22.5 ± 6.8°, while FO increased by 1.7 ± 3.5 mm to a postoperative FO of 42.9 ± 7.1 mm. FA and FA change were higher in patients with IFI (p ≤ 0.006), while no significant difference was observed for patients with and without GTPS (p ≥ 0.122). IFI was more common in females (p = 0.023). In the ROC analysis, an AUC of 0.859 was observed for FA change to predict IFI, whereas the AUC value was 0.726 for FA alone. No significant difference was found for FO change in patients with and without IFI or GTPS (p ≥ 0.187).

CONCLUSION

Postoperative FA, FA change, and female sex were associated with IFI after anterior-approached THA. The change in FA was a better predictor of IFI than absolute postoperative FA alone.

CLINICAL RELEVANCE STATEMENT

The findings of this study suggest that preservation of the preoperative femoral anteversion may reduce postoperative ischiofemoral impingement in patients undergoing total hip arthroplasty.

KEY POINTS

• Higher postoperative femoral anteversion and anteversion change were associated with ischiofemoral impingement. • Femoral anteversion change was a better predictor of impingement than absolute postoperative anteversion. • No significant association was found between femoral offset and postoperative hip pain.

Sagittal Pelvic Tilt Directly Influences the Ischiofemoral Space: A Cadaveric Study

BACKGROUND

Ischiofemoral impingement (IFI) is understood to be a pain generator in the deep gluteal space. Femoral position is known to influence the ischiofemoral space (IFS), but there has been no study examining the effect of sagittal pelvic tilt on the IFS. The purpose of this study was to determine whether changes in pelvic tilt in the sagittal plane lead to changes in the dimensions of the IFS.

MATERIALS AND METHODS

Five fresh frozen cadavers (10 hips) were used for this anatomic study. The specimens were skeletonized and placed in the prone position with the pelvis fixed to a custom-built hinged table. A digital inclinometer was used to tilt the pelvis -10°, 0°, and 10° simulating posterior, neutral, and anterior pelvic tilt, respectively. Digital calipers were used to measure the dimensions of the IFS in all three positions of sagittal pelvic tilt.

RESULTS

Changes in pelvic tilt resulted in significant changes in the dimensions of the IFS. Mean IFS dimensions measured 29.3±9.7 mm, 37.2±9.0 mm, and 24.3±9.2 mm in the neutral, anterior, and posterior pelvic tilt positions, respectively (P<.0001).

CONCLUSION

Changes in sagittal pelvic tilt influence the dimensions of the IFS, with posterior pelvic tilt noted to significantly decrease the IFS when compared with neutral and anterior pelvic tilt. These findings suggest that further evaluation of sagittal spinopelvic balance in the etiology of symptomatic IFI may be warranted. [Orthopedics. 2024;47(3):167-171.].

Stress Fracture after Arthroscopic Lesser Trochanter Resection: Diagnosis and Therapy

We report on the case of a 52-year-old female who presented with a stress fracture after undergoing an endoscopic resection of the lesser trochanter in ischiofemoral impingement, which was resistant to maximal conservative treatment. To the best of our knowledge, this complication has not been previously described. Non-weight-bearing and intravenous alendronic acid were prescribed for management. No additional surgery was required. The patient was pain free with the ability to perform sports on the same level as before and had no complaints.

CT-guided quadratus femoris injection for ischiofemoral impingement

OBJECTIVES

To describe the technique, efficacy, and safety of CT-guided quadratus femoris injection with corticosteroid and local anesthetic for the treatment of ischiofemoral impingement in a series of cases at our institution.

METHODS

Cases of CT-guided quadratus femoris injections from 2000 to 2021 were identified in the enterprise-wide electronic medical record of our institution. Patient charts and our institutional picture archiving and communication system (PACS) were searched for demographics, pain level on a 0-10 scale before and immediately following the procedure, procedure technique, and follow-up outcomes if available.

RESULTS

There were 13 cases among 12 patients with clinical and imaging findings of ischiofemoral impingement included in this study. Of the 12 patients, 10 were female and two were male. There were eight posterior approaches and five posterolateral approaches. Of the 13 cases, 11 resulted in immediate pain reduction. The median reduction in pain score was four (average 3.46, range 0-8.5). There was no statistically significant difference in pain reduction between the posterior approach cases and the posterolateral approach cases. No cases reported immediate complications or increases in pain score. Of the 12 cases, seven resulted in at least 1 month of pain relief, three had subsequent surgeries, and three had no follow-up.

CONCLUSION

CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. Further and larger scale study is needed to fully delineate differences in technique effectiveness.

KEY POINTS

• CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. • We found no statistically significant difference in pain reduction between the posterior approach and the posterolateral approach.

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.

Dynamic ultrasound assessment of hip instability and anterior and posterior hip impingement

OBJECTIVE

In this technical report, we describe our protocol for the dynamic sonographic evaluation of the hip and assess reliability of the ultrasound assessment of hip microinstability.

MATERIALS AND METHODS

Our clinical experience with a standardized dynamic ultrasound of the hip performed in a series of 27 patients with imaging performed by an experienced musculoskeletal radiologist during physical examination by an orthopedic surgeon specializing in hip preservation is illustrated with clinical photographs and ultrasound images from volunteers and selected patients. Interrater reliability for the diagnosis of microinstability was calculated.

RESULTS

Dynamic ultrasound technique and findings of hip instability, femoroacetabular impingement, and ischiofemoral impingement with corresponding clinical photos showing the necessary physical examination maneuvers are described. Interrater agreement for the diagnosis of microinstability was substantial (κ 0.606 [0.221-0.991]).

CONCLUSION

At our institution, dynamic ultrasound of the hip during physical examination complements information gathered from static imaging by providing real-time correlation of symptoms with what is occurring anatomically.

Ischiofemoral Impingement Syndrome: Clinical and Imaging/Guidance Issues with Special Focus on Ultrasonography

Ischiofemoral impingement syndrome is a neglected cause of posterior hip pain which is derived from narrowing of the space between the lateral aspect of the ischium and the medial aspect of the lesser trochanter. Its diagnosis is challenging and requires the combination of physical tests and imaging studies. In the present narrative review, we found that femoral anteversion predisposes patients to the narrowing of the ischiofemoral space and subsequent quadratus femoris muscle injury. Magnetic resonance imaging serves as the gold-standard diagnostic tool, which facilities the quantification of the ischiofemoral distance and the recognition of edema/fat infiltration/tearing of the quadratus femoris muscle. Ultrasound is useful for scrutinizing the integrity of deep gluteal muscles, and its capability to measure the ischiofemoral space is comparable to that of magnetic resonance. Various injection regimens can be applied to treat ischiofemoral impingement syndrome under ultrasound guidance and they appear to be safe and effective. Finally, more randomized controlled trials are needed to build solid bases of evidence on ultrasound-guided interventions in the management of ischiofemoral impingement syndrome.

Ischiofemoral impingement syndrome: a case report and review of literature

Introduction

The etiology of ischiofemoral impingement (IFI) syndrome, an unusual and uncommon form of hip pain, remains uncertain. Some patients demonstrate narrowing of the space between the ischial tuberosity and lesser trochanter from trauma or abnormal morphology of the quadratus femoris muscle. Combined clinical and imaging aid in the diagnosis.

Case report

A 32-year-old female presented with a 3 years history of pain over the lower aspect of the right buttock, aggravated by movements of the right hip, and partially relieved with rest and medications. The right hip showed extreme restriction of abduction and external rotation. MRI of the right hip showed reduced ischiofemoral space and quadratus femoris space when compared to the left hip. The patient underwent endoscopic resection of the right lesser trochanter, with no recurrence of pain at 2 years.

Conclusion

An unusual cause of hip pain, IFI syndrome, should be suspected when hip pain at extremes of movement is associated with signal abnormality of quadratus femoris muscle. Management is tailored to address the inciting factors that precipitated the IFI syndrome.

Open Ischiofemoral Impingement Decompression

Ischiofemoral impingement is a relatively rare cause of posterior hip pain associated with narrowing of the space between the lateral aspect of the ischium and the lesser trochanter. Symptoms typically consist of lower buttock, groin, and/or medial thigh pain, which is commonly exacerbated by adduction, extension, and external rotation of the hip. This condition can be treated nonoperatively in many circumstances; however, recalcitrant cases may require surgical intervention. Whereas described operative treatment options for this pathology range from endoscopic to open procedures, this Technical Note describes a safe and reliable technique for open ischiofemoral decompression with sciatic nerve neurolysis through a posterior approach for treatment of ischiofemoral impingement refractory to conservative treatment.

Ischiofemoral space dimensions for ischiofemoral impingement: is it different in children?

OBJECTIVE

This study intended to analyze alterations in ischiofemoral space (IFS) dimensions in normal children between the ages of 1 and 18 years for the ischiofemoral impingement.

MATERIALS AND METHODS

This study retrospectively focused on computed tomography images of 360 hips of 180 (90 boys and 90 girls) pediatric subjects (mean age: 9.50 ± 5.20 years, range: 1-18 years) without any hip disorders to measure IFS, femoral neck angle (FNA), and ischial angle (IA).

RESULTS

Mean IFS, FNA, and IA were measured as 14.64 ± 7.24 mm, 34.61 ± 11.47°, and 131.52 ± 4.22°, respectively. IFS increased in children aged between 1 and 18 years, whereas FNA and IA decreased. IFS was similar in infancy and early childhood periods but then increased up to postpubescent period. FNA decreased proportionally from birth, whereas IA decreased in an irregular pattern. Linear functions were detected as y = 3.451 + 1.178 × years for IFS, as y = 48.555 - 1.468 × years for FNA, and as y = 132.535 - 0.107 × years for IA.

CONCLUSION

Our findings indicate that IFS tends to increase in size with age during childhood but decreases with further aging. Therefore, age-specific values for IFS, FNA, and IA may be beneficial for clinicians and radiologists for the diagnosis of ischiofemoral impingement.

Arthroscopic Lesser Trochanter Osteoplasty, Quadratus Femoris Debridement, and Sciatic Neurolysis via Posterior Approach for Ischiofemoral Impingement

Ischiofemoral impingement (IFI) syndrome is considered the narrowing of the ischiofemoral space (IFS), leading to pathological changes in the quadratus femoris and sciatic nerve, causing posterior hip and sciatica-like pain. Open or arthroscopic resection of the lesser trochanter to enlarge the IFS is the main surgical procedure. However, there is a lack of research on isolated IFI, and currently known surgical procedures are at risk of weakening the flexion strength of the hip joint. In this study, four patients, who were diagnosed with isolated IFI and had undergone arthroscopic treatment with partial resection of the lesser trochanter, debridement of the quadratus femoris, and decompression of the sciatic nerve, were reviewed. To the best of our knowledge, this is the first study to describe the management of IFI using a series of surgical procedures via a posterior approach as an effective treatment option. The outcomes of this study broadened the strategies for IFI management.

Interpretation of ischiofemoral impingement via a clinical test using hip triaxial dynamic magnetic resonance imaging

BACKGROUND

The present study aimed to use magnetic resonance (MR) to explore the dynamic changes of the ischiofemoral space (IFS) under the triaxial motion of the hip joint and verify the clinical test mechanism for ischiofemoral impingement (IFI).

METHODS

A prospective design was used to screen 37 patients with clinically confirmed IFI, which included a total of 67 lateral hips, and 39 healthy controls with a total of 69 lateral hips. A dynamic MR examination was performed in positions designed by a simulated IFI test (adduction, adduction with 30° external rotation, 30° internal rotation, supine with 30° flexion, and prone with 30° backward extension). The IFS (mm) and quadratus femoris space (QFS, mm) were measured in different positions. All the data were evaluated independently by three musculoskeletal radiologists. The differences between the two groups were compared using the two-tailed t-test.

RESULTS

The IFS and QFS in the case group were smaller than those in the control group. The IFS and QFS were significantly reduced in the prone with backward extension and adduction with external rotation positions of the hip. The correlation coefficients of the IFI test and long-stride walking (LSW) test were -0.621 and -0.715 for IFS and -0.653 and -0.696 for QFS, respectively.

CONCLUSIONS

In this study, the mechanism of the IFI-specific clinical examination (IFI and LSW tests) was verified by triaxial dynamic MR imaging of the hip joint, which provided a dynamic imaging basis for the clinical application of the IFI-specific impingement test. The IFI impingement test can be used as a specific clinical test for IFI screening.

Deep Gluteal Pain in Orthopaedics: A Challenging Diagnosis

Identifying the specific source of gluteal pain can elude the most seasoned orthopaedic diagnosticians. Patients will often present with a protracted course of symptoms, and failure to successfully identify and treat the underlying etiology leads to frustration for both patient and clinician. Pain deep in the buttocks can arise from compression, inflammation, or injury of one or more of the structures in this anatomically dense area. Although sacroiliitis, hip arthritis, and trochanteric bursitis may also masquerade as gluteal pain, sciatic nerve irritation in its various presentations causes a substantial percentage of cases. Deep gluteal syndrome, hamstring syndrome, and ischiofemoral impingement can have overlapping presentations but can be differentiated by clinical examination and judiciously placed diagnostic corticosteroid injections. Although nonsurgical management, including physical therapy, relative rest, and injections represent the mainstay of treatment, open and endoscopic surgical approaches have yielded encouraging success rates in refractory cases.

Endoscopic Shelf Procedure and Ischiofemoral Decompression with Arthroscopic Acetabular Labral Reconstruction: A Case Report

CASE

A 43-year-old female patient complained of pain in the right hip. The diagnoses of hip dysplasia, ischiofemoral impingement (IFI), femoroacetabular (FAI) cam-type morphology, and labral tear were made. The patient underwent hip arthroscopy with labral reconstruction for an irreparable labral tear and cam-morphology correction, and hip endoscopy for shelf procedure and ischiofemoral decompression. Favorable outcomes were reported at 1-year follow-up.

CONCLUSION

Hip arthroscopy for FAI cam-type morphology with labral reconstruction and concomitant hip endoscopy for shelf and ischiofemoral decompression seem to be safe for the treatment of active young adult patients with FAI cam-type morphology, irreparable labral tear, dysplasia, and IFI diagnoses. Nevertheless, the results presented should not be extrapolated as this is a case report.

Piriformis Syndrome Masquerading as an Ischiofemoral Impingement

Hip pain can have a number of different etiologies. Ischiofemoral impingement (IFI), an etiology causing extra-articular hip pain, shares many of the same symptoms as other causes of gluteal or inguinal pain, making its diagnosis difficult. We present a case of a young female with persistent deep gluteal pain who was diagnosed with IFI based on radiographic findings; however, a diagnostic injection into the quadratus femoris did not confirm IFI as the primary pain generator. The patient subsequently failed several trials of physical therapy designed to address this diagnosis. The diagnosis was expanded to include piriformis syndrome and the modified treatment approach resulted in complete resolution of her pain. The similarities of these pathologies resulted in a delay of definitive treatment and would have potentially required unnecessary surgery. This case study highlights the diagnostic conundrum clinicians face in the evaluation of gluteal hip pain and provides an algorithm for considering alternate diagnoses when conservative management fails to achieve expected results.

Incidental finding of hereditary multiple osteochondroma causing ischiofemoral impingement

Ischiofemoral impingement (IFI) has been described in the medical literature as a cause of hip pain. IFI occurs due to an abnormal contact or reduced space between the lesser trochanter and the lateral border of the ischium and is an often unrecognised cause of pain and snapping in the hip. Association of multiple exostoses and a skeletal dysplasia characterised by an abnormal modelling of bone metaphysis and osseous deformities is highly characteristic of this disease. Consequently, multiple exostoses may narrow the ischiofemoral space and cause impingement and pain, even in the absence of malignant transformation. Surgical excision of exostosis of the lesser trochanter is a safe and effective method of treatment for patients with IFI. We present a case of left hip pain with incidental finding of hereditary multiple osteochondroma causing IFI and discuss the predisposing factors and review of literature.

A Novel Physical Examination Test for Ischiofemoral Impingement: Validation With Magnetic Resonance Imaging Correlation

OBJECTIVE

The purpose of this study was to propose and validate a novel physical examination test for ischiofemoral impingement with magnetic resonance imaging (MRI) correlation.

METHODS

We prospectively studied 24 women with buttock (deep gluteal) pain and 27 asymptomatic women. Each group underwent a 2-stage physical examination test that featured hip adduction-external rotation-extension and knee flexion. Visual analog scale pain scores were noted just before and during test stages on both sides. The MRI findings of the ischiofemoral impingement were evaluated quantitatively and qualitatively.

RESULTS

Mean ages were 56.0 and 55.2 years (P = 0.797), and mean body mass indexes were 29.1 and 28.8 kg/m2 (P = 0.817) in symptomatic and asymptomatic groups, respectively. Ischiofemoral spaces were significantly narrower (P < 0.001), ischial angles were wider (P < 0.001, right; P = 0.002, left), and soft tissue edema at the ischiofemoral space was more common (P < 0.001) in the symptomatic group, which also had higher pretest visual analog scale scores (P < 0.001) that increased significantly during both upright standing (P = 0.003, right; P < 0.001, left) and recumbent (P < 0.001 for both sides) stages of the physical examination test.

CONCLUSIONS

A novel physical examination test significantly increases symptoms of ischiofemoral impingement with positive MRI correlation.

Pain relief and good functional outcomes after hip endoscopy via posterior approach in patients with ischiofemoral impingement

PURPOSE

Ischiofemoral impingement is considered to be an uncommon and difficult pathology to diagnose with respect to hip pain etiology. The objective was to describe the clinical results of endoscopic lesser trochanter resection via a posterior approach in patients with Ischiofemoral impingement.

METHODS

This was a retrospective observational study of consecutive patients with Ischiofemoral impingement, who underwent endoscopic resection of the lesser trochanter via a posterior approach, between 2015 and 2018. Clinical results were evaluated using the ischiofemoral impingement test, long-stride walking test, modified Harris Hip Score (mHHS) and the Oxford scale to assess the strength of the iliopsoas muscle as well as the presence of complications. Preoperative and postoperative ischiofemoral space was measured to assess whether the resection of the lesser trochanter was adequate.

RESULTS

16 hips in 13 patients (mean age: 34.4 ± 12.1 years, 11 women) with a follow-up period between 24 and 59 months were included. Preoperative ischiofemoral space ranged from 6.4 to 22.4 mm, a measure > 17.0 mm was achieved in 15 hips without the presence of pain in IFI test and long-strides walking test. Function improved postoperatively, as reflected by a higher mean mHHS (preoperative: 44.6 ± 21.5, postoperative: 81.2 ± 15.1, p < 0.05). After surgery, the strength of the iliopsoas muscle was not decreased compared to the preoperative measure. Three complications were reported, including two cases that required revision surgery.

CONCLUSIONS

Endoscopic resection of the lesser trochanter via posterior approach provides satisfactory outcomes with symptom relief and good functional results in patients with Ischiofemoral impingement. It is important to discuss the benefits and risks when offering this treatment choice.

LEVEL OF EVIDENCE

Level IV.

Complications of Hip Endoscopy in the Treatment of Subgluteal Space Pathologies

PURPOSE

To assess complications of hip endoscopy in patients with subgluteal space pathologies.

METHODS

This was a retrospective study of patients diagnosed with sciatic nerve entrapment (SNE), ischiofemoral impingement (IFI), and rupture of the proximal origin of the hamstring muscles (RHM) who underwent a hip endoscopy from January 2012 to December 2018, after a minimum of 3 months of conservative management without satisfactory results. Complications were documented and graded using the adapted system of Clavien-Dindo. Revision surgeries were classified as treatment failures. Function was evaluated by the Western Ontario McMaster Universities Osteoarthritis Index before and 12 months after the surgical procedure.

RESULTS

A total of 97 hips with subgluteal space pathologies were treated with hip endoscopy. This total consisted of 77 hips with SNE, 5 with IFI, 12 with SNE + IFI, and 3 hips with RHM. Minor (Clavien-Dindo I-II) and major (Clavien-Dindo III-V) complications occurred in 7.22% (7) (95% confidence interval 3.54%-14.15%) and 12.37% (12) (95% confidence interval 7.22%-20.39%). Grade II, III, and IV complications were reported in 7.22% (7), 7.22%, and 5.15% (5) hips, respectively. Temporary nerve injury of the sciatic nerve, hematoma, and permanent nerve injury of the posterior femoral cutaneous nerve were the most common grade II, grade III, and grade IV complications, respectively. The revision rate was 6.19% (6) and entrapment of the sciatic nerve was the main cause of reoperation. No statistically significant differences were found between cases with and without complications in the Western Ontario McMaster Universities Osteoarthritis Index scores evaluated before and after surgery (P > .05).

CONCLUSIONS

A high rate of complications associated with hip endoscopy were observed in patients with SNE, IFI, and RHM. Sciatic nerve and posterior femoral cutaneous nerve injury were the most frequent events.

LEVEL OF EVIDENCE

IV, case series type.

A Current Update on Pelvifemoral Conditions That Should be in the Differential Diagnosis for Patients With Lower Extremity Radiculopathy

Patients presenting to an outpatient spine clinic frequently report symptoms of low back pain with associated buttock, groin, and lower extremity pain. While many of these individuals suffer from lumbar spine radiculopathy, a number of different orthopedic pathologies can mimic these symptoms. Management depends substantially on a detailed history and physical examination, in addition to working from a broad list of differential diagnoses when evaluating these patients. It is imperative that spine practitioners have a comprehensive understanding of the differential diagnoses that may mimic those originating from the lumbar spine, especially when a patient's symptoms are atypical from classic radicular pain. Misdiagnosis can lead to unnecessary testing and treatment, while delaying an accurate clinical assessment and treatment plan. This review highlights common orthopedic diagnoses that may present similar to lumbar spine pathologies and the evidence-based evaluation of these conditions.

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.

Ultrasound and Ultrasound-Guided Hip Injection Have High Accuracy in the Diagnosis of Femoroacetabular Impingement With Atypical Symptoms

PURPOSE

To evaluate the diagnostic value of ultrasound and ultrasound-guided hip injection in the diagnosis of femoroacetabular impingement (FAI) with atypical symptoms.

METHODS

We evaluated consecutive patients diagnosed with FAI and with atypical symptoms who underwent ultrasound-guided hip injection between January 2017 and February 2019. All patients underwent systematic physical examination, ultrasound examination, magnetic resonance imaging (MRI) examination, and ultrasound-guided injection before surgery. Patients with positive response to ultrasound-guided hip injection were recommended to undergo arthroscopic surgery to treat intra-articular pathology. Sensitivity, specificity, accuracy, and positive predictive value (PPV) of ultrasound and MRI were calculated by using arthroscopic surgery as the gold standard. The accuracy of ultrasound-guided hip injection was recorded. Preoperative and postoperative patient-reported outcomes included visual analog scale for pain and modified Harris Hip Score.

RESULTS

A total of 78 patients with atypical symptoms were diagnosed with FAI. Among these 78 patients, 50 patients had positive responses to injection and 28 patients had negative responses to injection. A total of 36 patients finally underwent arthroscopic surgery. Response to the ultrasound-guided intra-articular injection was 91.7% accurate for detecting the presence of intra-articular abnormality. There were no complications of injection in any of the patients. The sensitivity, PPV, and accuracy by ultrasound diagnosis of cam impingement were 82.9%, 96.7%, and 80.6%, respectively. The sensitivity and accuracy by ultrasound diagnosis of anterosuperior labral tear were both 72.2%. For MRI diagnosis of cam impingement, the sensitivity, PPV and accuracy were 72.2%, 96.3%, and 74.3%, respectively. For MRI diagnosis of labral tear, the sensitivity and accuracy were both 88.9%. Thirty-four patients (94.4%) surpassed the minimal clinically important difference, and 33 patients (91.7%) achieved the patient acceptable symptomatic state.

CONCLUSIONS

Ultrasound and ultrasound-guided hip injection have high accuracy in the diagnosis of femoroacetabular impingement with atypical symptoms.

LEVEL OF EVIDENCE

IV, case series.

Kinematic MRI of ischiofemoral impingement

OBJECTIVE

To examine the effect of external hip rotation on ischiofemoral (IF) and quadratus femoris (QF) spaces using real-time kinematic MRI, with the hypothesis that hips with IF and QF space narrowing have distinct motion patterns compared with control hips.

MATERIALS AND METHODS

This prospective study was IRB-approved and complied with HIPAA guidelines. We recruited women (≥ 18 years) with and without ischiofemoral impingement to undergo kinematic MRI of the hips. A kinematic imaging protocol using T2-HASTE was performed beginning at maximal internal rotation followed by active external hip rotation. The duration of each acquisition was 30 s, providing 8 images/3 s. IF and QF spaces, and femoral metaphyseal and lesser trochanter centroid coordinates were measured on sequential images. Hips were classified as controls or narrowed based on IF and QF space thresholds and compared statistically throughout motion stages.

RESULTS

The cohort comprised 12 women (24 hips; 10 control and 14 narrowed hips) aged 58 ± 10 years. External rotation caused IF space reduction of 59% in narrowed hips versus 41% in control hips. QF space decreased 71% in narrowed hips versus 50% in control hips. IF and QF spaces differed significantly between groups only when external rotation exceeded the neutral position (P < 0.02 for both). The lesser trochanter terminated more posteriorly in narrowed hips compared with controls (P = 0.03).

CONCLUSIONS

Kinematic MRI during external hip rotation in women with narrowed and control hips reveals dynamic differences in IF and QF spaces and lesser trochanter terminal position.

Frequency of ischiofemoral space discrepancy when comparing magnetic resonance images of distinct institutions for the same patient

Inaccuracy of ischiofemoral space (IFS) measurement may result in radiographic misdiagnosis of ischiofemoral impingement, as well as insufficient or excessive osseous resection when surgery is indicated. This study compared the IFS measured in magnetic resonance imaging (MRI) performed in distinct health services for the same patient. Sixty-five patients (95 hips) who had hip MRI performed at an outside institution (noncontrolled MRI) followed by a hip MRI with lower extremity positioning reproducing the standing position (controlled MRI) were studied. For each hip, the IFS measured in the noncontrolled MRI was compared to the IFS measured in the controlled MRI. The categorization of a hip as presenting decreased IFS (≤17 mm) or normal IFS (>17 mm) changed in 19% of the hips when comparing the noncontrolled MRI to the controlled MRI. From the 32 hips (34%) with a difference ≥4 mm in the IFS, the predominant positioning change was hip flexion/extension in 47%, hip rotation in 44%, and hip abduction/adduction in 9%. In conclusion, a difference >4 mm in the IFS was observed in 1 out of every 3 hips when comparing noncontrolled MRI with controlled MRI reproducing the lower limb positioning in the standing position.

Hip-spine syndrome: rationale for ischiofemoral impingement, femoroacetabular impingement and abnormal femoral torsion leading to low back pain

The term 'hip-spine syndrome' was introduced in recognition of the frequent occurrence of concomitant symptoms at the hip and lumbar spine. Limitations in hip range of motion can result in abnormal lumbopelvic mechanics. Ischiofemoral impingement, femoroacetabular impingement and abnormal femoral torsion are increasingly linked to abnormal hip and spinopelvic biomechanics. The purpose of this narrative review is to explain the mechanism by which these three abnormal hip pathologies contribute to increased low back pain in patients without hip osteoarthritis. This paper presents a thorough rationale of the anatomical and biomechanical characteristics of the aforementioned hip pathologies, and how each contributes to premature coupling and limited hip flexion/extension. The future of hip and spine conservative and surgical management requires the implementation of a global hip-spine-pelvis-core approach to improve patient function and satisfaction.

Deep gluteal syndrome as a cause of posterior hip pain and sciatica-like pain

Deep gluteal syndrome is an increasingly recognized disease entity, caused by compression of the sciatic or pudendal nerve due to non-discogenic pelvic lesions. It includes the piriformis syndrome, the gemelli-obturator internus syndrome, the ischiofemoral impingement syndrome, and the proximal hamstring syndrome. The concept of the deep gluteal syndrome extends our understanding of posterior hip pain due to nerve entrapment beyond the traditional model of the piriformis syndrome. Nevertheless, there has been terminological confusion and the deep gluteal syndrome has often been undiagnosed or mistaken for other conditions. Careful history-taking, a physical examination including provocation tests, an electrodiagnostic study, and imaging are necessary for an accurate diagnosis. After excluding spinal lesions, MRI scans of the pelvis are helpful in diagnosing deep gluteal syndrome and identifying pathological conditions entrapping the nerves. It can be conservatively treated with multidisciplinary treatment including rest, the avoidance of provoking activities, medication, injections, and physiotherapy. Endoscopic or open surgical decompression is recommended in patients with persistent or recurrent symptoms after conservative treatment or in those who may have masses compressing the sciatic nerve. Many physicians remain unfamiliar with this syndrome and there is a lack of relevant literature. This comprehensive review aims to provide the latest information about the epidemiology, aetiology, pathology, clinical features, diagnosis, and treatment. Cite this article: Bone Joint J 2020;102-B(5):556-567.

Is there a relationship between femoral neck-shaft angle and ischiofemoral impingement in patients with hip pain?

Ischiofemoral impingement (IFI) is a cause of deep gluteal space syndrome. The prevalence of radiographic findings in patients with hip pain is unknown. To assess if there is a correlation between femoral neck-shaft angle (NSA) and the distance of the ischiofemoral space (IFS) and quadratus femoris space (QFS) and to determine the prevalence of quadratus femoris (QF) edema in patients with hip pain. A retrospective case series was conducted involving 100 consecutive hip or pelvis magnetic resonance imaging scans on patients presenting with hip pain. NSA, IFS and QFS distances were measured and presence of QF edema was noted. Analysis of the groups (QF edema vs no edema) was performed using two-tailed t-test and Pearson correlation. There were 18 hips in the edema group (mean age 51.11 years ± 10.5) and 82 hips in the non-edema group (mean age 40.79 years ± 15.9). Within the edema group, there was a moderate positive correlation between NSA and QFS (r = 0.498, P = 0.036) and a weak positive correlation between NSA and IFI (0.312, P = 0.208). The prevalence of QF edema in this study was 18% with only 28% of those subjects having clinical symptoms of IFI. Patients with QF edema had significantly narrower QFS and IFS distances (P < 0.001). The prevalence of QF edema is 18% in a consecutive sample of adults with hip pain. In patients with QF edema, only 28% have symptoms of IFI. In patients with QF edema, there was a moderate positive correlation between NSA and QFS.

Atypical Hip Pain in Femoroacetabular Impingement: A Comparison of Outcomes Based on Primary Hip Pain Location

BACKGROUND

Patients with symptomatic femoroacetabular impingement (FAI) typically have anterior groin pain. However, a subset of these patients may have pain located laterally, posteriorly, or in a combination of locations around the hip.

PURPOSE

To report and compare outcomes of hip arthroscopy for patients with FAI and atypical hip pain versus classic anterior groin pain.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Consecutive patients undergoing hip arthroscopy for FAI between August 2011 and March 2013 were identified. A total of 258 patients were identified as having symptomatic FAI based on clinical, radiographic, and advanced imaging diagnosis of FAI. Exclusion criteria included isolated thigh, knee, or low back pain. We also excluded patients with hip abductor pathology and trochanteric bursitis. Of the 226 patients ultimately included, 159 (70.4%) reported anterior groin pain, while 67 (29.6%) reported isolated lateral or posterior hip pain or a combination of locations. Patients were categorized into 4 groups: isolated anterior groin pain, lateral hip pain, posterior hip pain, and multiple primary hip pain locations (combined). These patients were followed prospectively with a minimum follow-up of 2 years. Patient characteristics, surgical characteristics, modified Harris Hip Score (mHHS), Non-arthritic Hip Score (NAHS), revision hip arthroscopy, and conversions to total hip arthroplasty (THA) were recorded.

RESULTS

All 226 patients were included at final follow-up. Hip arthroscopy was performed by a single sports medicine fellowship-trained orthopaedic surgeon. Preoperative patient characteristics and baseline functional outcome scores did not significantly differ among groups. All 4 groups showed statistically significant improvements in mHHS and NAHS from baseline to final follow-up of a mean 2.63 years (range, 2.01-3.23 years). Functional outcome scores and rates of revision hip arthroscopy or conversion to THA did not significantly differ between groups.

CONCLUSION

Hip arthroscopy can effectively improve patient outcomes in atypical hip pain. A careful history and physical examination should identify this clinically meaningful subset of patients with FAI who can benefit from surgical intervention while identifying patients with concomitant posterior extra-articular hip or spine pathology that should be addressed appropriately.

Editorial Commentary: A-version to a Pain in the Butt-Structural and Dynamic Determinants of Posterior Hip Pain

Ischiofemoral impingement is becoming a more recognized source of buttock pain that occurs as the lesser trochanter of the femur approximates the lateral margin of the ischium. Abnormal bony structure and alignment of the hip joint and/or faulty dynamic movement patterns may decrease the ischiofemoral space and compress the structures that are found within the space, including the quadratus femoris, proximal hamstring tendons, and sciatic nerve. The ischiofemoral space is reduced by structural factors including an increase in femoral anteversion and femoral neck angle. Dynamic assessment of the hip region may include the Craig test and total rotational range of motion of the hip joint, as well as the ischiofemoral impingement test and the long-stride walking test. The combination of structural and dynamic assessment of the hip region may help determine the presence of ischiofemoral impingement and direct appropriate management of the condition.

Is the ischiofemoral space value of Japanese hip joints equal to that of Western populations?

Ischiofemoral space (IFS) is a radiological parameter employed for diagnosing ischiofemoral impingement (IFI). The mean IFS value measured with the leg in natural resting position has been reported as 23.0 mm in males and 18.6 mm in females in a patients-based Western population. The normal value of IFS for an Asian population is unknown. This study therefore aimed to investigate whether the IFS value in Japanese hip joints equals that of the Western population. We retrospectively examined 89 consecutive Japanese individuals (178 hips) (46 male subjects with 92 hips, 43 female subjects with 86 hips; mean age 58.7 ± 15.7 years, range 17-84 years) who had undergone computed tomography (CT) for conditions unrelated to hip disorders and ordered by other departments at our institution. All CT scans were performed in a standardized fashion: patient in a flat spine position, hips and knees in extension, and the leg in its natural resting position. IFS was evaluated on axial images as the shortest distance between the ischium and the lesser trochanter. The mean IFSs of this Japanese patient-based population were 20.5 ± 7.3 mm [95% confidence interval (CI) 19.0-22.0] in the male cohort and 13.9 ± 6.5 mm (95% CI 12.6-15.3) in the female cohort. The IFS value was significantly smaller in female subjects than in male subjects. Taking the lower limit of 95% CI into consideration, the IFSs measured in natural leg-resting position in the Japanese male and female groups were significantly smaller than those of the Western populations.

Extra-articular hip impingement: clinical presentation, radiographic findings and surgical treatment outcomes

Femoroacetabular impingement syndrome is classically thought of as either a cam or pincer deformity causing abnormal bony contact resulting in labral pathology. However, alternate patterns of hip impingement can occur, but tend to be less commonly recognized or studied. Collectively termed 'extra-articular impingement', four subgroups of impingement can contribute to non-arthritic hip pain and disability: iliopsoas impingement, subspine impingement, ischiofemoral impingement and trochanteric-pelvic impingement. The purpose of this review article is to highlight the pertinent points to aid in proper clinical and radiographic evaluation to allow appropriate diagnosis. Additionally, a review of potential surgical treatment options and resultant outcomes will also be provided.

Evaluation of the ischiofemoral space: a case-control study

Objective

To determine the size of the ischiofemoral space (IFS) and quadratus femoris space (QFS) in patients with and without ischiofemoral impingement (IFI).

Materials and Methods

Case-control study including consecutive patients submitted to magnetic resonance imaging (MRI) of the hip joint during a three-month period. Patients with deep gluteal pain who tested positive for IFI on at least one clinical test and showed signal changes in the quadratus femoris muscle on MRI were categorized as having a confirmed diagnosis of IFI.

Results

Final sample comprised 50 patients submitted to unilateral MRI of the hip joint. The mean age was 47.3 ± 14.0 years (range, 22-76 years), and 33 (66%) of the patients were women. A diagnosis of IFI was made in 6 patients (12%), all of whom were female. On average, IFS and QFS were significantly smaller in IFI group than in control group (11.1 ± 2.7 mm versus 27.5 ± 6.5 mm and 5.3 ± 1.8 mm versus 18.8 ± 4.8 mm, respectively; p < 0.001 for both).

Conclusion

Results of specific clinical tests and MRI findings indicate that the IFS and QFS are significantly reduced in patients with IFI.

Current Concepts Review: Evaluation and Management of Posterior Hip Pain

Understanding the etiology of and evolving research on intra- and extra-articular hip complaints requires comprehensive diagnosis and management of the spectrum of posterior hip diseases. Interest in posterior hip disorders has increased in recent years as new studies and theories have emerged regarding the disease process. Although most of the differential diagnoses around the posterior hip have traditionally been considered uncommon, recent reports suggest that these complaints have instead been commonly overlooked. Failure to identify the cause of posterior hip pain in a timely manner can increase pain perception, deteriorate the patient's hope, and consequently affect quality of life. Posterior hip pain could be differentiated as intrapelvic and extrapelvic, and differential diagnosis is made based on a comprehensive history, physical examination, and imaging studies. Plain radiography, CT, MRI, 3T MRI, and imaging-guided injection tests are usually necessary for accurate diagnosis. Surgical intervention, whether endoscopic or open, is required for patients with long-standing symptoms for whom nonsurgical treatment has been unsuccessful and who have experienced temporary relief of their symptoms after injection. Orthopedic surgeons are uniquely trained in understanding the anatomy, biomechanics, clinical evaluation and treatment of all five layers of the hip.

Endoscopic Lesser Trochanter Resection With Refixation of the Iliopsoas Tendon for Treatment of Ischiofemoral Impingement

Ischiofemoral impingement is a source of hip pain derived from impingement between the lesser trochanter and the ischium. Lesser trochanter excision has been recommended for recalcitrant ischiofemoral impingement through either an anterior or posterior approach. However, neither of these approaches involves refixation of the iliopsoas tendon. We describe an endoscopic procedure involving anterior trochanter-plasty, minimizing the risk of sciatic complications, with refixation of the partially detached iliopsoas tendinous insertion, potentially minimizing compromise to hip flexion strength and anterior hip stability.

[Surgical therapy of ischiofemoral impingement by lateralizing intertrochanteric osteotomy]

OBJECTIVE

Lateralizing, derotating intertrochanteric varus osteotomy to increase the ischiofemoral space to counter painful impingement of the lesser trochanter and the os ischium with resulting entrapment of quadratus femoris muscle.

INDICATIONS

Symptomatic ischiofemoral impingement (IFI) caused by Coxa valga et antetorta, Coxa valga or Coxa antetorta, or a short femoral neck.

CONTRAINDICATIONS

Anatomic configuration suggestive of IFI in asymptomatic patients. Symptomatic IFI caused by another underlying pathology. Valgus deformity of the knee.

SURGICAL TECHNIQUE

Measurement of femoral antetorsion. Planning of the osteotomy, lateralization, varus angle for correction, rotation and offset correction, leg length change, and osteosynthesis plate. General or spinal anesthesia in supine or lateral position. Skin incision (15 cm) beginning lateral of the greater trochanter tip, distally along the axis of the femur. Preparation onto the femur by L‑shaped dissection of the vastus lateralis from the bone. A Kirschner(K-)wire is then positioned along the anterior femoral neck to designate the femoral neck antetorsion. A triangle set on the lateral femoral cortexis is used to determine the osteotomy angle. In the thus determined angle, a second K‑wire is shot centrally along the femoral neck axis just inferior to its cranial cortex. About 5 mm distal to the second wire, the entry for the blade is prepared using a drill. Using the blade setting instrument, the blade is introduced into the femoral neck, then slightly pulled back. The rotation is then marked on the anterior femoral cortex proximal and distal to the planned osteotomy and the osteotomy is performed. A blade plate without displacement is impacted. The osteotomy is then reduced, the distal fragment pulled laterally onto the plate, and the screws inserted after compression of the osteotomy with a tension device.

POSTOPERATIVE MANAGEMENT

Touch-toe bearing for 6 weeks, then radiological assessment of osteotomy healing before an increase in weight bearing (15 kg/week). Hip flexion limited to 90° for 6 weeks. Elective implant removal after 12-18 months.

RESULTS

Studies of this lateralizing varus osteotomy have not been published. The 25-year results of the conventional derotating intertrochanteric varus osteotomy technique show good functional results and low complication rates, with non-union being the most common. Arthroscopic resection of the lesser trochanter has been reported as a surgical alternative in the treatment of IFI in case reports and small series. Advantages of the osteotomy are the restoration of biomechanics and preservation of iliopsoas tendon insertion.

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.

In Vivo Measurements of the Ischiofemoral Space in Recreationally Active Participants During Dynamic Activities: A High-Speed Dual Fluoroscopy Study

BACKGROUND

Ischiofemoral impingement (IFI) is a dynamic process, but its diagnosis is often based on static, supine images.

PURPOSE

To couple 3-dimensional (3D) computed tomography (CT) models with dual fluoroscopy (DF) images to quantify in vivo hip motion and the ischiofemoral space (IFS) in asymptomatic participants during weightbearing activities and evaluate the relationship of dynamic measurements with sex, hip kinematics, and the IFS measured from axial magnetic resonance imaging (MRI).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Eleven young, asymptomatic adults (5 female) were recruited. 3D reconstructions of the femur and pelvis were generated from MRI and CT. The axial and 3D IFS were measured from supine MRI. In vivo hip motion during weightbearing activities was quantified using DF. The bone-to-bone distance between the lesser trochanter and ischium was measured dynamically. The minimum and maximum IFS were determined and evaluated against hip joint angles using a linear mixed-effects model.

RESULTS

The minimum IFS occurred during external rotation for 10 of 11 participants. The IFS measured from axial MRI (mean, 23.7 mm [95% CI, 19.9-27.9]) was significantly greater than the minimum IFS observed during external rotation (mean, 10.8 mm [95% CI, 8.3-13.7]; P < .001), level walking (mean, 15.5 mm [95% CI, 11.4-19.7]; P = .007), and incline walking (mean, 15.8 mm [95% CI, 11.6-20.1]; P = .004) but not for standing. The IFS was reduced with extension (β = 0.66), adduction (β = 0.22), and external rotation (β = 0.21) ( P < .001 for all) during the dynamic activities observed. The IFS was smaller in female than male participants for standing (mean, 20.9 mm [95% CI, 19.3-22.3] vs 30.4 mm [95% CI, 27.2-33.8], respectively; P = .034), level walking (mean, 8.8 mm [95% CI, 7.5-9.9] vs 21.1 mm [95% CI, 18.7-23.6], respectively; P = .001), and incline walking (mean, 9.1 mm [95% CI, 7.4-10.8] vs 21.3 mm [95% CI, 18.8-24.1], respectively; P = .003). Joint angles between the sexes were not significantly different for any of the dynamic positions of interest.

CONCLUSION

The minimum IFS during dynamic activities was smaller than axial MRI measurements. Compared with male participants, the IFS in female participants was reduced during standing and walking, despite a lack of kinematic differences between the sexes. The relationship between the IFS and hip joint angles suggests that the hip should be placed into greater extension, adduction, and external rotation in clinical examinations and imaging, as the IFS measured from static images, especially in a neutral orientation, may not accurately represent the minimum IFS during dynamic motion. Nevertheless, this statement must be interpreted with caution, as only asymptomatic participants were analyzed herein.

How to address ischiofemoral impingement? Treatment algorithm and review of the literature

Ischiofemoral impingement (IFI) is a rare cause of hip pain defined by a narrowing of the space between the lateral aspect of the os ischium and the lesser trochanter of the femur. Several underlying anatomic, functional and iatrogenic pathologies have been identified for symptomatic IFI in native hip joints and after total hip arthroplasty. Clinical symptoms vary but most commonly consist of pain of the lower buttock and groin including the inner thigh, and a snapping or clunking phenomenon is often reported. Symptoms may be provoked by a combined extension, adduction and external rotation during physical examination and during long-stride walking. Radiographs of the pelvis and an axial or false-profile-view of the hip as well as magnetic resonance imaging (MRI)-scans should be obtained to strengthen the diagnosis. On MRI, the quadratus femoris muscle signal and the space confined by the anatomic structures surrounding the muscle, the quadratus femoris space, are to be assessed. Targeted infiltration of the muscle can be helpful both diagnostically and therapeutically. The literature on differential diagnoses and treatment options for IFI is limited; therapeutic suggestions are offered only in case reports and series. With this work, we aim to give a systematic approach to the non-surgical and surgical treatment options for IFI based upon the current literature and the authors' personal experience.

Musculoskeletal Approach to Pelvic Pain

Visceral and somatic causes of pelvic pain are often inter-related, and a musculoskeletal examination should always be considered for the successful diagnosis and treatment of pelvic pain. For the diverse etiologies of hip pain, there are many unique considerations for the diagnosis and treatment of these various disorders. Pelvic pain is often multidimensional due to the overlap between lumbo-hip-pelvic diagnoses and may require a multidisciplinary approach to evaluation and management.

Hip Arthroscopy for Atypical Posterior Hip Pain: A Comparative Matched-Pair Analysis

BACKGROUND

Femoroacetabular impingement (FAI) most commonly manifests as anterior groin pain. Patients occasionally have posterior pain but otherwise have clinical and radiographic evidence of FAI.

PURPOSE

To compare outcomes of hip arthroscopy for FAI in patients with atypical posterior pain versus a matched group with the typical anterior pain presentation.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing primary hip arthroscopy for FAI were identified from a clinical repository between January 2012 and 2014. Of 503 patients during the study period, 31 (6.2%) had posterior hip or buttock pain reproduced with flexion, adduction, and internal rotation (FADDIR) and were classified as "atypical," while those with anterior hip or groin pain were classified as "typical." Atypical patients were matched in a 1:2 cohort to the typical group based on sex, age, and body mass index (BMI). Postoperative patient-reported outcomes included visual analog scale (VAS) for pain, modified Harris Hip Score (mHHS), and Hip Outcome Scores with Activities of Daily Living (HOS-ADL) and Sports-Specific (HOS-SS) subscales.

RESULTS

Of the 31 atypical patients, 28 (90.3%) were available for a minimum 2-year follow-up (mean ± SD, 2.6 ± 0.6 years). These patients were matched with 56 typical patients. No differences were noted between typical and atypical cohorts in preoperative demographic or radiographic parameters. Postoperatively, both groups demonstrated significant improvements in mHHS (atypical 60.1 ± 12.4 to 78.8 ± 12.9; typical 60.0 ± 12.3 to 76.9 ± 13.6; P < .001), HOS-ADL (atypical 68.5 ± 17.0 to 88.6 ± 11.0; typical 69.2 ± 17.1 to 86.8 ± 14.7; P < .001), and HOS-SS (atypical 42.0 ± 25.5 to 71.0 ± 26.2; typical 44.4 ± 24.9 to 71.3 ± 27.3; P < .001). No differences were found in 2-year score improvements between the atypical and typical cohorts (mHHS 18.7 ± 13.4 vs 16.9 ± 13.1, P = .48; HOS-ADL 20.1 ± 16.8 vs 17.6 ± 14.6, P = .19; HOS-SS 29.0 ± 30.2 vs 26.9 ± 27.3, P = .93). Also, no significant differences were found in VAS pain improvement (5.0 ± 3.2 vs 5.6 ± 2.8, P = .56) or postoperative satisfaction (79.5 ± 5.5 vs 77.5 ± 4.1, P = .78).

CONCLUSION

Atypical posterior hip pain is an uncommon presentation of FAI. Patients demonstrate similar significant improvements after hip arthroscopy in outcome scores, postoperative pain, and satisfaction compared with patients who have classic anterior groin pain.

Editorial Commentary: Ischiofemoral Impingement: Is This the "New" Femoroacetabular Impingement?

In a single-surgeon study of more than 1,000 hip operations, 30 patients were identified with possible ischiofemoral impingement (IFI). Only 17 of these 30 (56.6%) patients ultimately were diagnosed as having IFI on the basis of magnetic resonance imaging, injections, arthroscopy, and the 2 clinical tests described. The IFI test and the long-stride walking test were both highly accurate for the purported diagnosis; however, the most accurate test that was not specifically prospectively studied was quadriceps muscle edema on magnetic resonance imaging, which was present only in otherwise confirmed cases of IFI and not seen with any other diagnosis.

A MRI study of the lesser trochanteric version and its relationship to proximal femoral osseous anatomy

The purpose of this study is to quantify the lesser trochanteric version and determine the angle and the relationship between lesser trochanter and femoral neck version. Investigate the influence of the lesser trochanter version in the width of ischiofemoral space. Two hundred and fifty asymptomatic hips were evaluated with axial magnetic resonance image. The lesser trochanter version was calculated. The difference between the femoral neck version and the lesser trochanter version formed the angle between each structure. The width of ischiofemoral space was measured and its relationship with the lesser trochanter version was determined. The mean lesser trochanter version was -24° ± 11.5° (range, - 54° to + 17°) with a coefficient variation of 47.45%. The mean femoral neck version measured 14.0° ± 10.8° (range, -16° to 50°), with a coefficient variation of 81.32%. The lesser trochanter/femora neck angle was 38.4° ± 9.6° (range, 8° to 67°), coefficient variation of 30%, with a moderate correlation between the structures (r = 0.63, P < 0.01). The mean ischiofemoral space was 22.9.0 ± 7.0 mm (range, 10.3 to 55 mm), and a weak correlation was found between ischiofemoral space and lesser trochanteric version (r = -0.16, P < 0.05). The lesser trochanteric version showed a high variation with a moderate relationship with the femoral neck version. The lesser trochanteric version does not influence the width of the ischiofemoral space.