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

Anatomical Proximity Between Sciatic Nerve and Ischial Spine and its Relationship to the Development of Deep Gluteal Pain Syndrome

OBJECTIVE

Deep gluteal syndrome (DGS) is a medical diagnosis in which the pathoanatomy of the subgluteal space contributes to pain. The growing recognition that gluteal neuropathies can be associated with the presence of a bone-neural conflict with irritation or compression may allow us to shed some light on this pathology. This study aims to determine whether the location of the sciatic nerve (SN) in relation to the ischial spine (IS) contributes to the development of DGS.

METHODS

The SN - IS relationship was analyzed based on magnetic resonance imaging (MRI) in 15 surgical patients (SPs), who underwent piriformis release, and in 30 control patients who underwent MRI of the pelvis for reasons unrelated to sciatica. The SN exit from the greater sciatic foramen was classified as either zone A (medial to the IS); zone B (on the IS); or zone C (lateral to the IS).

RESULTS

The SN was significantly closer to the IS in SPs than in MRI controls (P = 0.014). When analyzing patients of similar age, SNs in SPs were significantly closer (P = 0.0061) to the IS, and located in zone B significantly more (P = 0.0216) as compared to MRI controls. Patients who underwent surgery for piriformis release showed a significant decrease in pain postoperatively (P < 0.0001).

CONCLUSIONS

The results from this study suggest that the relationship between the IS and SN may play a role in the development of DGS. This may also help establish which patients would benefit more from surgical intervention.

Cadaveric investigation best shows the balance of structure, movement, and function, particularly in the hip joint: We owe a debt to human donors

Cadaveric investigation of the pathomechanics of hip ischiofemoral impingement syndrome is revealing, and shows that hip external rotation reduces the ischiofemoral space, as does hip extension, combined femoral and acetabular anteversion, and coxa valga. "Impingement syndromes" are a combined failure of compatibility of the anatomy to the desired movement pattern. 3D models based on CT imaging can create a patient specific model that predicts area of collision area and points of impact during multiplanar movement. 3D models based on MRI of the hip shows higher frequency of extra-articular impingement at early stages of external rotation and extension in hips that displayed ischiofemoral impingement compared to non-impinging hips. However, a limit of fluoroscopy as well as 3D modeling is that soft tissue is not revealed. Cadaveric dissection reveals muscle, nerve, and blood vessels that best explain the pathoanatomy. We owe a great debt not only to researchers, but also to human cadaveric gift donors.

Cauda equina, conus medullaris and syndromes mimicking sciatic pain: WFNS spine committee recommendations

Introduction

Cauda equina syndrome (CES), conus medullaris syndrome (CMS), and sciatica-like syndromes or "sciatica mimics" (SM) may present as diagnostic and/or therapeutic dilemmas for the practicing spine surgeon. There is considerable controversy regarding the appropriate definition and diagnosis of these entities, as well as indications for and timing of surgery. Our goal is to formulate the most current, evidence-based recommendations for the definition, diagnosis, and management of CES, CMS, and SM syndromes.

Methods

We performed a systematic literature search in PubMed from 2012 to 2022 using the keywords "cauda equina syndrome", "conus medullaris syndrome", "sciatica", and "sciatica mimics". Standardized screening criteria yielded a total of 43 manuscripts, whose data was summarized and presented at two international consensus meetings of the World Federation of Neurosurgical Societies (WFNS) Spine Committee. Utilizing the Delphi method, we generated seven final consensus statements.

Results and conclusion

s: We provide standardized definitions of cauda equina, cauda equina syndrome, conus medullaris, and conus medullaris syndrome. We advocate for the use of the Lavy et al classification system to categorize different types of CES, and recommend urgent MRI in all patients with suspected CES (CESS), considering the low sensitivity of clinical examination in excluding CES. Surgical decompression for CES and CMS is recommended within 48 h, preferably within less than 24 h. There is no data regarding the role of steroids in acute CES or CMS. The treating physician should be cognizant of a variety of other pathologies that may mimic sciatica, including piriformis syndrome, and how to manage these.

Importance of Sacrotuberous Ligament in Transgluteal Approach for Sciatic Nerve Entrapment in the Greater Sciatic Notch (Piriformis Syndrome)

OBJECTIVE

The efficacy of sciatic nerve decompression via transgluteal approach for entrapment of the sciatic nerve at the greater sciatic notch, called piriformis syndrome, and factors affecting the surgical outcome were analyzed.

METHODS

The outcome of pain reduction was analyzed in 81 patients with sciatic nerve entrapment who underwent decompression through a transgluteal approach. The patients were followed up for at least 6 months. The degree of pain reduction was analyzed using a numerical rating scale-11 (NRS-11) score and percent pain relief before and after last follow-up following surgery. Success was defined by at least 50% reduction in pain measured via NRS-11. To assess the degree of subjective satisfaction, a 10-point Likert scale was used. In addition, demographic characteristics, anatomical variations, and variations in surgical technique involving sacrotuberous ligamentectomy were analyzed as factors that affect the surgical outcome.

RESULTS

At a follow-up of 17.5±12.5 months, sciatic nerve decompression was successful in 50 of 81 patients (61.7%), and the pain relief rate was 43.9±34.17. Subjective improvement based on a 10-point Likert scale was 4.90±3.43. Among the factors that affect the surgical outcome, only additional division of the sacrotuberous ligament during piriformis muscle resection played a significant role. The success rate was higher in the scarotuberous ligementectomy group (79.4%) than in the non-resection group (42.6%), resulting in statistically significant difference based on average NRS-11 score, percent pain relief, and subjective improvement (p<0.05, independent t-test).

CONCLUSION

Sciatic nerve decompression is effective in pain relief in chronic sciatica due to sciatic nerve entrapment at the greater sciatic notch. Its effect was further enhanced by circumferential dissection of the sciatic nerve based on the compartment formed by the piriformis muscle and the sacrotuberous ligament in the greater sciatic notch.

Anatomical Relationships of the Sciatic Nerve and Pudendal Nerve to the Ischial Spine as They Exit the Greater Sciatic Foramen

OBJECTIVE

Deep gluteal syndrome is a clinical condition in which discomfort may arise due to the pathoanatomy of the subgluteal space. We conducted an anatomical exploration to categorize the relationship of the piriformis muscle, sciatic nerve (SN), and pudendal nerve (PN) to the ischial spine (IS) and sacrospinous ligament.

METHODS

We analyzed 22 cadavers. The piriformis muscle, SN, and PN were exposed through either a transgluteal approach or a gluteal flap. The relationship of the neural structures to the IS, sacrospinous ligament, and ischial bone as they exit the greater sciatic foramen was observed, and the exit zones were classified as zone A, medial to the IS (entirely on sacrospinous ligament); zone B, on the IS; and zone C, lateral to the IS (entirely on ischial bone).

RESULTS

The SN was observed either in zone B or zone C in all specimens. The PN was found to be in either zone A or zone B in 97.6% of specimens. The most common combinations were SN in zone B and PN in zone A (type I), and SN in zone C and PN in zone B (type II).

CONCLUSIONS

The results from this study show clear anatomical differences in the SN-PN relationship, which may play a role in pain seen in deep gluteal syndrome. Moreover, classification of the SN-IS and PN-IS relationships described in this article will help describe different pathologies affecting the deep gluteal area.

A comprehensive review of hip arthroscopy techniques and outcomes

Transforming the orthopedic landscape, hip arthroscopy pioneers a minimally invasive surgical approach for diagnosing and addressing hip pathologies. With its origins dating back to Burman's 1931 cadaveric study, this groundbreaking technique gained clinical relevance in 1939 through Takagi's report. However, the 1980s marked the actual emergence of hip arthroscopy for treating a wide range of hip disorders. Now, a staple in modern orthopedics, hip arthroscopy empowers patients with previously undiagnosed and untreated hip conditions, enabling them to obtain relief and reclaim their lives. By employing a compact camera and specialized tools, surgeons expertly navigate the hip joint, performing procedures from excising loose bodies and mending labral tears to addressing femoroacetabular impingement and tackling other intricate issues. This innovative approach has dramatically elevated patients' quality of life, allowing them to embrace targeted treatments and resume daily activities without resorting to lifestyle alterations.

Division of neuromuscular compartments and localization of the center of the intramuscular nerve-dense region in pelvic wall muscles based on Sihler's staining

The innervation of the pelvic wall muscles is not very clear. This study aimed to reveal the division of neuromuscular compartments and localize the surface position and depth of the center of the intramuscular nerve-dense region (CINDR) of the pelvic wall muscles based on Sihler's staining. Twenty-four adult cadavers were used. To localize the CINDR of the pelvic wall muscles, horizontal (H) and longitudinal (L) reference lines were drawn, and Sihler's staining was used to reveal the intramuscular nerve distribution. The CINDR projection points (P and P' points) behind and in front of the body surface, the positions of the P points projected onto the H and L lines (PH and PL points), and the depth of CINDR were determined by spiral computed tomography scanning. The piriformis and obturator internus muscles can be divided into two and three neuromuscular compartments, respectively. The PH of CINDR of the piriformis muscle was located at 22.61 ± 2.66% of the H line, the PL was at 28.53 ± 6.08% of the L line, and the puncture depth of the piriformis muscle was at 24.64 ± 2.16% of the PP' line. The PH of CINDR of the obturator internus muscle was at 16.49 ± 1.20% of the H line, the PL was at 10.94 ± 1.09% of its L line, and the puncture depth was 6.26 ± 0.38 cm. These findings may guide the design of the compartmentalized transplantation of the pelvic wall muscles and improve the target localization efficiency and efficacy for injecting botulinum toxin A to treat pelvic wall muscle spasm.

Piriformis syndrome

Piriformis syndrome is a condition that is proposed to result from compression of the sciatic nerve, either in whole or in part, in the deep gluteal space by the piriformis muscle. The prevalence of piriformis syndrome depends upon the diagnostic criteria being used and the population studied but is estimated by some to be 5%-6% in all cases of low back, buttock, and leg pain and up to 17% of patients with chronic low back pain. While the sciatic nerve may pierce the piriformis muscle in about 16% of healthy individuals, this frequency is no different in those with the syndrome; thus, the relationship to this anatomic finding is unclear. The most common symptoms are buttock pain, external tenderness over the greater sciatic notch, and aggravation of the pain through sitting. Many clinical signs are reported for piriformis syndrome, but the sensitivity and specificity are unclear, in part because of the lack of a uniformly accepted case definition. In the majority of cases in the literature, it appears that the diagnosis is more ascribed to a myofascial condition rather than a focal neuropathy. Electrodiagnostic studies can be useful to exclude other causes of symptoms, but there is no well-accepted test to confirm the presence of piriformis syndrome. Ultrasound imaging may show thickening of the piriformis muscle, but further research is required to confirm that this is correlated with the clinical diagnosis. Magnetic resonance imaging and neurography may hold promise in the future, but there are not yet sufficient data to support adopting these methods as a standard diagnostic tool. The initial treatment of piriformis syndrome is typically conservative management with the general rehabilitation principles similar to other soft tissue musculoskeletal conditions. Local anesthetic, botulinum toxin, and/or corticosteroid injections have been reported by some to be beneficial for diagnostic or treatment purposes. Surgical interventions have also been used with variable success.

Inter- and Intra-Examiner Reliability Study of Two-Point Discrimination Test (TPD) and Two-Point Estimation Task (TPE) in the Sacral Area of Pain-Free Individuals

Tactile acuity is typically measured by a two-point discrimination test (TPD) and a two-point estimation task (TPE). In the back area, they are only conducted in the lumbar and cervical regions of the spine. Considering that such measurements have not been conducted in the sacral regions, the purpose of this study was to assess the inter- and intra-examiner reliability of the TPD and TPE at the level of the S3 segment. The study included 30 pain-free subjects aged 20-30 years. Tests were performed with a pair of stainless hardened digital calipers. The TPD was measured in two locations: 5 and 15 cm from the midline; for TPE both, points were located inside the measured area. Session 1 involved assessments by two examiners in 10-min intervals. Session 2 was measured by one examiner, at analogous intervals between tests. The TPD inter-rater reliability was excellent for mean measurements (ICC3.2: 0.76-0.8; ICC3.3: 0.8-0.92); the intra-rater reliability was excellent for mean measurements (ICC2.2: 0.79-0.85; ICC2.3: 0.82-0.86). The TPE inter-rater reliability was good to excellent for mean measurements (ICC3.2: 0.65-0.92; ICC3.3: 0.73-0.94); the intra-rater reliability for all studies (ICC2.1, ICC2.2, ICC2.3) was excellent (0.85-0.89). Two measurements are sufficient to achieve good reliability (ICC ≥ 0.75), regardless of the assessed body side.

Diagnostic Approach to Lower Limb Entrapment Neuropathies: A Narrative Literature Review

Entrapment neuropathies of the lower limb are a misunderstood and underdiagnosed group of disorders, characterized by pain and dysesthesia, muscular weakness, and specific provoking movements on physical examination. The most frequent of these syndromes encountered in clinical practice are fibular nerve entrapment, proximal tibial neuropathy, sural nerve neuropathy, deep gluteal syndrome or sciatic nerve entrapment, and lateral femoral cutaneous nerve entrapment, also known as meralgia paresthetica. These are commonly mistaken for lumbar plexopathies, radiculopathies, and musculotendinous diseases, which appear even more frequently and have overlapping clinical presentations. A comprehensive anamnesis, physical examination, and electrodiagnostic studies should help clarify the diagnosis. If the diagnosis is still unclear or a secondary cause of entrapment is suspected, magnetic resonance neurography, MRI, or ultrasonography should be conducted to clarify the etiology, rule out other diseases, and confirm the diagnosis. The aim of this narrative review was to help clinicians gain familiarity with this disease, with an increase in diagnostic confidence, leading to early diagnosis of nerve damage and prevention of muscle atrophy. We reviewed the epidemiology, anatomy, pathophysiology, etiology, clinical presentation, and EDX technique and interpretation of the entrapment neuropathies of the lower limb, using articles published from 1970 to 2022 included in the Pubmed, MEDLINE, Cochrane Library, Google Scholar, EMBASE, Web of Science, and Scopus databases.

A systematic review of conservative and surgical treatments for deep gluteal syndrome

BACKGROUND AND OBJECTIVE

Conservative and surgical treatments, are recommended as the primary treatment in the management of patients diagnosed with deep gluteal syndrome; but evidence supporting superiority of one treatment over another is lacking. The aim of this review is to systematically review the effectiveness of treatments.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, Web of Science, Scopus, AMED, Cochrane Library (Central Register of Controlled Trials), and PEDro were screened (to 24 July 2019). Risk of bias of trials and surgical case series were assessed using the Cochrane risk of bias tool and Joanna Briggs Institute Critical appraisal checklists, respectively. Outcomes were reductions in pain or disability. For each outcome, the minimum clinically important difference (MCID) was calculated. A narrative synthesis was performed.

RESULTS

Out of 909 records, thirteen studies with 508 patients were included, eight RCTs with 336 patients and 5 case series with 172 patients. Conservative modalities were: infiltration into muscle of steroid, botulinum toxin, thiochilcoside and colchicine. There was one RCT and five case series of surgery. Only three trials reached an MCID in pain reduction for the intervention. The five surgical studies reached a before and after MCID. Only one study showed an MCID reduction in disability. The overall quality of evidence was low.

CONCLUSION

Given the low quality of evidence, no single conservative treatment can be recommended over another. Clinicians should follow general guidelines on the management of back pain and sciatica for first line treatment, namely physiotherapy. Surgery may have a place for chronic cases.

High-resolution ultrasound in the evaluation of the adult hip

This paper reviews ultrasound of the hip, which is a commonly requested examination for symptomatic hip issues. This includes both intra-articular and extra-articular causes of hip pain. Ultrasound is easily accessible, lacks radiation exposure, and allows for evaluation of the contralateral hip as well as assessment of dynamic maneuvers. Ultrasound can be used to guide interventional procedures. Ultrasound of the hip can be challenging due to the deep location of structures and complex anatomy. Typically, high-frequency transducers are used to examine the hip, however the choice of ultrasound transducer depends on the patient's body habitus, with lower frequency transducers required to penetrate deep structures in obese patients. It is important to have an approach to ultrasound of the hip which includes assessment of the anterior, lateral, posterior, and medial aspects of the hip. The technique and relevant anatomy of each of these compartments are discussed as well as the use of Doppler examination of the hip. Several dynamic maneuvers can be performed to help determine the cause of hip pathology in various locations, and these are described and illustrated. Ultrasound is useful for guided procedures about the hip, and these indications will be reviewed.

[Chronic Back Pain]

Chronic back pain is one of the most common diseases in Germany. In many cases, no morphological change is found, so that the genesis remains unspecific in over 90% of patients. This article is intended to provide an overview of drug therapy as well as non-drug measures and summarizes the corresponding guideline recommendations.

Özkan F. Radiological Comparison of Femoral Neck-Shaft Angle in Piriformis Syndrome: A Case-Control Study

Introduction

Variations in osseous, neural and muscular anatomical structures in the gluteal region have been investigated for their role in causing deep gluteal pain syndromes including piriformis syndrome. This study aimed to radiologically determine whether the femoral neck-shaft angle (NSA) in piriformis syndrome differs from that in a healthy population.

Methods

Two groups of participants comprising 23 piriformis syndrome patients and 22 healthy controls were included in the present study. Piriformis syndrome was diagnosed based on clinical findings and the diagnosis was confirmed by intramuscular local anaesthetic injection. Femoral NSAs were measured from the anteroposterior pelvic radiographs and compared between the control and piriformis syndrome-affected groups.

Results

The age, height, body weight, body mass index and gender distribution differences between the two groups (control and piriformis) were not statistically significant. The femur NSA was significantly lower in the piriformis group than in the control group. The receiver operating characteristic analysis revealed that the area under the curve, sensitivity and specificity for predicting the risk of piriformis syndrome (PS) were 0.946%, 100% and 86.36%, respectively, at an NSA cut-off of 127°.

Conclusions

Reduced femoral NSA is related to PS. However, studies with a larger study sample are needed to further substantiate this finding.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-022-00736-y.

Use of botulinum neurotoxin in the treatment of piriformis syndrome: A systematic review

OBJECTIVE

To determine the pain, functional and adverse outcomes of patients with piriformis syndrome who received botulinum neurotoxin injection, and to determine the optimal dosing of botulinum neurotoxin and choices of modality used during this intervention.

LITERATURE SURVEY

Systematic review of relevant clinical studies published in English language using PubMed/Medline, Embase and CINAHL databases from October 1, 2002 to October 6, 2020.

METHODOLOGY

A comprehensive search was performed to identify all studies addressing the treatment of piriformis syndrome with botulinum toxin. Two reviewers independently screened the titles, abstracts, and full texts and extracted data based on a set of predefined inclusion and exclusion criteria. 23 full-text articles were identified of which consensus was achieved for seven articles for data extraction and quality assessment. The qualities and risk of potential bias of the seven studies were appraised using the National Heart, Lung and Blood Institute (NIH) Study Quality Assessment tools for case controls, cohort studies and randomized trials.

SYNTHESIS

Seven studies (n = 152 patients) were included consisting of three randomized controlled studies (RCTs), two case control studies and two cohort studies. The qualities of these studies were: Two good and one fair for the RCTs, fair for both the case controls and one good and fair for the cohort studies. Most studies reported some reduction in pain using various modalities to guide injection (CT, EMG, US or fluoroscopy). However, the included studies were heterogeneous, making it difficult to quantify pain reduction. There was minimal description of other functional outcomes. Botulinum toxin A doses range from 100 to 300U. Mild adverse effects were reported with no medical intervention needed.

CONCLUSIONS

There is fair quality of evidence to suggest botulinum toxin is safe to reduce pain in piriformis syndrome. There is insufficient data to quantify pain reduction and to describe other functional outcomes. The optimal dose of botulinum toxin A remains unclear. Modalities to guide botulinum injection into the piriformis muscle remain heterogeneous.

A Retrospective Comparative Study of Modified Percutaneous Endoscopic Transforaminal Discectomy and Open Lumbar Discectomy for Gluteal Pain Caused by Lumbar Disc Herniation

Introduction

This study aimed to demonstrate the safety and effectiveness of modified percutaneous endoscopic transforaminal discectomy (PETD) in the surgical management of single-segment lumbar disc herniation (LDH) gluteal pain and to determine whether it provides a better clinical outcome than open lumbar discectomy (OD).

Methods

A retrospective analysis of patients treated with modified PETD and OD for gluteal pain in LDH from January 2015 to December 2020 was conducted. Sample size was determined using a priori power analysis. Demographic information, surgical outcomes including procedure time (minutes), intraoperative blood loss (mL), hospital days, costs (RMB), fluoroscopy shots, recurrence and complications, etc., were recorded and analyzed. Prognostic outcomes were assessed using the visual analog scale (VAS), the Oswestry Disability Index (ODI), the Japanese Orthopedic Association Score (JOA) and modified MacNab criteria. The preoperative and postoperative VAS, ODI and JOA scores were recorded by two assistants. When the results were inconsistent, the scores were recorded again by the lead professor until all scores were consistently recorded in the data. MRI was used to assess radiological improvement and all patients received follow-ups for at least one year.

Results

The sample size required for the study was calculated by a priori analysis, and a total of 72 participants were required for the study to achieve 95% statistical test power. A total of 93 patients were included, 47 of whom underwent modified PETD, and 46 of whom underwent OD. In the modified PETD intragroup comparison, VAS scores ranged from 7.14 ± 0.89 preoperatively to 2.00 ± 0.58, 2.68 ± 0.70, 2.55 ± 0.69, 2.23 ± 0.81, and 1.85 ± 0.72 at 7 days, 1 month, 3 months, 6 months, and 12 months postoperatively. Patients showed significant pain relief postoperatively (P &lt; 0.01). According to the modified MacNab score, the excellent rate in the PETD group was 89.36%. There was no significant difference compared to the OD group (89.13%, P &gt; 0.05). Complication rates were lower (P &gt; 0.05) but recurrence rates were higher (P &gt; 0.05) in the modified PETD group than in the OD group. The modified PETD group had a faster operative time (P &lt; 0.01), shorter hospital stay (P &lt; 0.01), less intraoperative bleeding (P &lt; 0.01), and less financial burden to the patient (P &lt; 0.01) than the OD group. At 7 days postoperatively, the VAS score for low back pain was higher in the OD group than in the modified PETD group (P &lt; 0.01). The VAS and JOA scores at 1, 3, 6, and 12 months postoperatively were not significantly different between the modified PETD and OD groups (P &gt; 0.05), and the ODI was significantly different at 3 months postoperatively (P &lt; 0.05).

Conclusion

Modified PETD treatment is safe and effective for gluteal pain due to L4/5 disc herniation and has the advantages of a lower complication rate, faster postoperative recovery, shorter length of stay, fewer anesthesia risks and lower cost of the procedure compared with OD. However, modified PETD has a higher recurrence rate.

Overview of the anatomical basis of the piriformis syndrome-dissection with magnetic resonance correlation

The piriformis syndrome is one of the most commonly misdiagnosed causes of lower back and gluteal pain caused by the compression of the sciatic nerve and the internal pudendal neurovascular bundle by the piriformis muscle. Although this syndrome was first suggested over 90 years ago, its diagnosis still represents a challenge for clinicians. In the present study, dissection was used to determine the intra- and extrapelvic anatomical course of the internal pudendal nerve and the data were compared with the information obtainable through MRI examination, in order to identify the piriformis syndrome and to differentiate it from other causes of internal pudendal neuralgia. Thorough dissections of the pelvis and deep gluteal region were conducted on female cadavers, which were correlated with MRI scans, in order to describe the course of the internal pudendal nerve in contact with the piriformis muscle. The dissection findings and MRI scans obtained allowed us to describe and demonstrate the compression points along the course of the sciatic nerve and the internal pudendal bundle, the anatomical correlations between the piriformis muscle and the nervous structures around it, emphasizing the areas most susceptible to possible nerve impingement syndromes. In the anatomic trajectory of the sciatic nerve and the internal pudendal bundle there are multiple contact points with anatomical structures that may lead to compression of the nerve structures, generating symptoms that comprise the piriformis syndrome. The present study sought to establish clear osseous landmarks that may help evaluate these associations and possible nerve compressions on pelvic MRI examination.

Inferior gluteal pain with sitting, unrelated to ischial bursitis

A 64-year-old woman presented to an academic medical centre with postoperative left ischial pain following a left total hip replacement. Her pain was exacerbated by sitting down and with forward flexion of the spine, and the pain radiated from the left ischial tuberosity to the left perineum, groin and medial thigh. An ischial bursa injection was performed, but only resulted in 1 day of excellent pain relief. A diagnosis of inferior cluneal neuralgia was then made. Subsequent inferior cluneal nerve radiofrequency ablation was performed, and provided sustained 50% relief in pain. The patient had a concomitant sensation of 'ball like' pressure at her rectum which was determined to be due to levator ani syndrome. She was prescribed pelvic floor physical therapy and botulinum toxin injection, which resulted in further notable improvement of her symptoms.

Assessing Sciatic Nerve Excursion and Strain with Ultrasound Imaging during Forward Bending

Entrapment neuropathies affecting the sciatic nerve tract may adversely affect neural biomechanical features such as excursion and strain. There is a paucity of in vivo evidence examining the effects of forward bending upon sciatic nerve excursion and strain. The purpose of this study was to assess the reliability of ultrasound imaging in measuring sciatic nerve excursion and strain during forward bending movements. Secondary aims were to quantify sciatic nerve excursion and strain during forward bending movements and to assess the relationship between sciatic nerve excursion and movements of the hip and lumbar spine. The reliability of measuring sciatic nerve excursion was high to excellent whilst measurement of sciatic nerve strain was moderate. The amount of hip flexion, during forward bending, was a strong predictor of sciatic nerve excursion. These findings will support clinicians in the assessment and treatment of entrapment neuropathies, in addition to providing a foundation for future research.

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.

Editorial Commentary: Subgluteal Hip Arthroscopy for Sciatic Nerve Entrapment, Ischiofemoral Impingement, or Proximal Hamstring Tears: Beyond the Comfort Zone

Advancements in hip arthroscopy are astounding. Circumferential labral reconstruction, labral augmentation, and capsular reconstruction are valuable tools. Beyond the "comfort zone" of the hip intra-articular realm, new frontiers include the peritrochanteric space, and a similarity to the subacromial space of the shoulder makes the transition attainable. In contrast, the subgluteal space is seen as outside the box. Sciatic nerve entrapment (SNE), ischiofemoral impingement (IFI), and tears of the proximal origin of the hamstring are among the subgluteal space pathologies. Clinical assessment of deep gluteal syndrome, defined as nondiscogenic sciatic nerve entrapment, can be particularly difficult but is critical and one of the skills that we as hip sports surgeons need to master. The respective treatments for SNE, IFI, and hamstring tears are nerve decompression, lesser trochanteric resection, and hamstring repair. Complications can occur, most commonly temporary injury of the sciatic nerve and permanent injury of the posterior femoral cutaneous nerve. While all located in the deep gluteal space, SNE, IFI, and proximal hamstring tears are unique entities. When thinking outside the box, it's important to consider the complicated contents of Pandora's box.

Sensory Innervation of the Hip Joint and Referred Pain: A Systematic Review of the Literature

OBJECTIVES

The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches innervating the hip joint and the distribution of sensory receptors within its capsule.

METHODS

Five electronic databases were queried, with the search encompassing articles published between January 1945 and June 2019. Twenty-one original articles providing a detailed description of sensory receptors around the hip joint capsule (n=13) and its articular branches (n=8) were reviewed.

RESULTS

The superior portions of the anterior capsule and the labrum were found to be the area of densest nociceptive innervation. Similar to the distribution of nociceptors, mechanoreceptor density was found to be higher anteriorly than posteriorly. Hip joint capsular innervation was found to consistently involve the femoral and obturator nerves, which supply the anterior capsule, and the nerve to the quadratus femoris, which supplies the posterior capsule. The femoral, obturator, and superior gluteal nerves supply articular branches to the most nociceptor-rich region of the hip capsule.

CONCLUSIONS

The femoral and obturator nerves and the nerve to the quadratus femoris were found to consistently supply articular branches to both the anterior and posterior capsule of the hip joint. The anterior capsule, primarily supplied by the femoral and obturator nerves, and the superior labrum appear to be the primary pain generators of the hip joint, given their higher density of nociceptors and mechanoreceptors.

LEVEL OF EVIDENCE

Anatomy study, literature review.

Ultrasound-guided injections in pelvic entrapment neuropathies

Pelvic entrapment neuropathies represent a group of chronic pain syndromes that significantly impede the quality of life. Peripheral nerve entrapment occurs at specific anatomic locations. There are several causes of pelvic entrapment neuropathies, such as intrinsic nerve abnormality or inflammation with scarring of surrounding tissues, and surgical interventions in the abdomen, pelvis and the lower limbs. Entrapment neuropathies in the pelvic region are not widely recognized, and still tend to be underdiagnosed due to numerous differential diagnoses with overlapping symptoms. However, it is important that entrapment neuropathies are correctly diagnosed, as they can be successfully treated. The lateral femoral cutaneous nerve, ischiadic nerve, genitofemoral nerve, pudendal nerve, ilioinguinal nerve and obturator nerve are the nerves most frequently causing entrapment neuropathies in the pelvic region. Understanding the anatomy as well as nerve motor and sensory functions is essential in recognizing and locating nerve entrapment. The cornerstone of the diagnostic work-up is careful physical examination. Different imaging modalities play an important role in the diagnostic process. Ultrasound is a key modality in the diagnostic work-up of pelvic entraptment neuropathies, and its use has become increasingly widespread in therapeutic procedures. In the article, the authors describe the background of pelvic entrapment neuropathies with special focus on ultrasound-guided injections.

Surgical and Non-surgical Treatment Options for Piriformis Syndrome: A Literature Review

Context

Piriformis syndrome is a solely clinical diagnosis that often eludes the practitioner and goes underdiagnosed. PS is a pain syndrome and for those it affects, causes persistent pain and limits daily activity and work capacity. It is a form of deep gluteal syndrome that needs to be considered on the differential of low back pain as it comprises between 0.3% - 6% of all low back pain cases and is frequently underdiagnosed. Piriformis syndrome may be primary due anatomic anomalies or secondary, though the majority of cases are secondary to some insult. The objective of this manuscript is to provide a description of the epidemiology and presentation of piriformis as well as both non-operative and operative treatment options. We review all of the recent clinical evidence regarding the aforementioned therapies.

Evidence Acquisition

Literature searches were performed using the below MeSH Terms using Mendeley version 1.19.4. Search fields were varied until further searches revealed no new articles. All articles were screened by title and abstract. Decision was made to include an article based on its relevance and the list of final articles was approved three of the authors. This included reading the entirety of the article. Any question regarding the inclusion of an article was discussed by all authors until an agreement was reached.

Results

Medical management and physical therapy show some promise; however, when conservative treatment fails minimally invasive methods such as steroid injections, botulinum toxin injections, dry needling are all efficacious and there is substantial clinical evidence regarding these therapies. In those patients in which minimally invasive techniques do not result in an adequate relief of pain and return of function, endoscopic release can be considered. Endoscopic release is far superior to open release of the piriformis syndrome given the higher success and lower rate of complications.

Conclusions

Piriformis syndrome is an important differential diagnosis in the work up of lower back pain and should not be ruled out with proper examination and testing. Clinicians should consider medical management and conservative management in the initial treatment plan for piriformis syndrome. There are many options within the conservative management and the literature shows much promise regarding these. Physical therapy, steroid injections, botulinum toxin injections, and dry needling are all potentially effective therapies with few adverse effects. Surgical options remain as gold standard, but only when conservative management has failed and the symptoms are significant to affect daily living activities. Endoscopic decompression of the sciatic nerve with or without release of the piriformis muscle has a reported high likelihood of success and a low complication rate. Current literature supports the preference of the endoscopic approach over the open approach due to improved outcomes and decreased complications. Further research is to well define the metrics for the diagnosis of piriformis syndrome and may include a need to develop diagnostic criteria.

Pudendal nerve entrapment syndrome caused by ganglion cysts along the pudendal nerve

Pudendal nerve entrapment (PNE) syndrome refers to the condition in which the pudendal nerve is entrapped or compressed. Reported cases of PNE associated with ganglion cysts are rare. Deep gluteal syndrome (DGS) is defined as compression of the sciatic or pudendal nerve due to a non-discogenic pelvic lesion. We report a case of PNE caused by compression from ganglion cysts and treated with steroid injection; we discuss this case in the context of DGS. A 77-year-old woman presented with a 3-month history of tingling and burning sensations in the left buttock and perineal area. Ultrasonography showed ganglion cystic lesions at the subgluteal space. Magnetic resonance imaging revealed cystic lesions along the pudendal nerve from below the piriformis to the Alcock’s canal and a full-thickness tear of the proximal hamstring tendon. Aspiration of the cysts did not yield any material. We then injected steroid into the cysts, which resolved her symptoms. Steroid injection into a ganglion cyst should be considered as a treatment option for PNE caused by ganglion cysts.