Visualization of bone formation in sheep's middle ear by using fluorochrome sequential labelling (FSL).

One factor for the lacking integration of the middle ear stapes footplate prosthesis or the missing healing of stapes footplate fractures could be the known osteogenic inactivity. In contrast, it was recently demonstrated that titanium prostheses with an applied collagen matrix and immobilised growth factors stimulate osteoblastic activation and differentiation on the stapes footplate. Regarding those findings, the aim of this study was to evaluate the potential of bone regeneration including bone remodeling in the middle ear. Ten one-year-old female merino sheep underwent a middle ear surgery without implantation of middle ear prostheses or any other component for activating bone formation. Post-operatively, four fluorochromes (tetracycline, alizarin complexion, calcein green and xylenol orange) were administered by subcutaneous injection at different time points after surgery (1 day: tetracycline, 7 days: alizarin, 14 days: calcein, 28 days: xylenol). After 12 weeks, the temporal bones including the lateral skull base were extracted and histologically analyzed. Fluorescence microscopy analysis of the entire stapes with the oval niche, but in particular stapes footplate and the Crura stapedis revealed evidence of new bone formation. Calcein was detected in all and xylenol in 60% of the animals. In contrast, tetracycline and alizarin could only be verified in two animals. The authors were able to demonstrate the osseoregenerative potential of the middle ear, in particular of the stapes footplate, using fluorescence sequence labelling.

Low-cost simulation model for ultrasound-guided punch biopsy and puncture: Construction manual and photo examples.

PURPOSE: Ultrasound-guided puncture and punch biopsy pose a particular challenge in ultrasound examination training. These techniques should be learned and performed several times using a simulation model that is as realistic as possible before being applied to patients. While the use of agar-agar-based models is extensively documented in the literature, there is a discernible gap in publications specifically addressing their use in punch biopsy and puncture. The aim was to develop a cost-effective model for the simulation of ultrasound-guided interventions. MATERIALS AND METHODS: The developed simulation model is based on the vegetable gelatine agar-agar. The agar-agar powder is boiled in water and colored. Various objects are added to the mass. Blueberries, olives, tomatoes, and cornichons imitate solid structures. Liquid-filled balloons are used to simulate cystic structures. Adding stones can make the exercises more difficult due to hyperechoic reflexes with distal shadowing. RESULTS: With the model, ultrasound-guided puncture and punch biopsies could be successfully simulated, and ultrasound images can be generated for this purpose. The cost of a single model is about 2 euros. Production takes less than 2 hours, including cooling. The pure processing time is 30 minutes. The durability of the models is limited by mold, which occurs after 5 days when stored at room temperature and after 5 weeks in the refrigerator. CONCLUSION: It was shown that it is possible to produce an inexpensive agar-agar-based ultrasound model in a short time and with easily available ingredients to learn ultrasound-guided puncture and punch biopsies.

The value of subcutaneous xenografts for individualised radiotherapy in HNSCC: Robust gene signature correlates with radiotherapy outcome in patients and xenografts.

PURPOSE: To assess the robustness of prognostic biomarkers and molecular tumour subtypes developed for patients with head and neck squamous cell carcinoma (HNSCC) on cell-line derived HNSCC xenograft models, and to develop a novel biomarker signature by combining xenograft and patient datasets. MATERIALS AND METHODS: Mice bearing xenografts (n = 59) of ten HNSCC cell lines and a retrospective, multicentre patient cohort (n = 242) of the German Cancer Consortium-Radiation Oncology Group (DKTK-ROG) were included. All patients received postoperative radiochemotherapy (PORT-C). Gene expression analysis was conducted using GeneChip Human Transcriptome Arrays. Xenografts were stratified based on their molecular subtypes and previously established gene classifiers. The dose to control 50 % of tumours (TCD50) was compared between these groups. Using differential gene expression analyses combining xenograft and patient data, a gene signature was developed to define risk groups for the primary endpoint loco-regional control (LRC). RESULTS: Tumours of mesenchymal subtype were characterized by a higher TCD50 (xenografts, p < 0.001) and lower LRC (patients, p < 0.001) compared to the other subtypes. Similar to previously published patient data, hypoxia- and radioresistance-related gene signatures were associated with high TCD50 values. A 2-gene signature (FN1, SERPINE1) was developed that was prognostic for TCD50 (xenografts, p < 0.001) and for patient outcome in independent validation (LRC: p = 0.007). CONCLUSION: Genetic prognosticators of outcome for patients after PORT-C and subcutaneous xenografts after primary clinically relevant irradiation show similarity. The identified robust 2-gene signature may help to guide patient stratification, after prospective validation. Thus, xenografts remain a valuable resource for translational research towards the development of individualized radiotherapy.

A Novel 2-Metagene Signature to Identify High-Risk HNSCC Patients amongst Those Who Are Clinically at Intermediate Risk and Are Treated with PORT.

(1) Background: Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) who are biologically at high risk for the development of loco−regional recurrences after postoperative radiotherapy (PORT) but at intermediate risk according to clinical risk factors may benefit from additional concurrent chemotherapy. In this matched-pair study, we aimed to identify a corresponding predictive gene signature. (2) Methods: Gene expression analysis was performed on a multicenter retrospective cohort of 221 patients that were treated with postoperative radiochemotherapy (PORT-C) and 283 patients who were treated with PORT alone. Propensity score analysis was used to identify matched patient pairs from both cohorts. From differential gene expression analysis and Cox regression, a predictive gene signature was identified. (3) Results: 108 matched patient pairs were selected. We identified a 2-metagene signature that stratified patients into risk groups in both cohorts. The comparison of the high-risk patients between the two types of treatment showed higher loco−regional control (LRC) after treatment with PORT-C (p < 0.001), which was confirmed by a significant interaction term in Cox regression (p = 0.027), i.e., the 2-metagene signature was indicative for the type of treatment. (4) Conclusion: We have identified a novel gene signature that may be helpful to identify patients with high-risk HNSCC amongst those at intermediate clinical risk treated with PORT, who may benefit from additional concurrent chemotherapy.

[Vestibular schwannomas - baseline and progress diagnostics]. / Vestibularisschwannome ­ Basis- und Verlaufsdiagnostik.

Vestibular (vestibulocochlear) schwannomas are rare, benign schwannomas of the cerebellopontine angle, the internal auditory canal, or the inner ear. They can occur with or without clinical symptoms. The most common symptoms are unilateral or side-differentiated hearing loss with or without tinnitus and balance disorders. Initial symptomatology is nonspecific in the basic functional diagnosis, raising the question of when a hearing or balance disorder should be thought of as a differential diagnosis of vestibular schwannoma and what diagnostic pathway is appropriate. This concerns not only the confirmation of the diagnosis and the recording of all dysfunctions of the involved cranial nerves in the initial basic diagnostics, but also the procedure in the course and follow-up diagnostics - especially in patients who are subject to an observation strategy. Today, imaging alone is no longer sufficient for differentiated and individualized patient counseling. Due to the increasing detection of smaller tumors on MRI and the growing proportion of nearly asymptomatic patients, a shift in thinking from pure imaging monitoring to a detailed analysis of auditory and vestibular function is timely. In this educational article, diagnostic pathways for a sufficient patient consultation will be compiled. Ultimately, functional examination techniques from follow-up and progression diagnostics will also be included.

Assessment of gene expressions from squamous cell carcinoma of the head and neck to predict radiochemotherapy-related xerostomia and dysphagia.

PURPOSE: We tested the hypothesis that gene expressions from biopsies of locally advanced head and neck squamous cell carcinoma (HNSCC) patients can supplement dose-volume parameters to predict dysphagia and xerostomia following primary radiochemotherapy (RCTx). MATERIAL AND METHODS: A panel of 178 genes previously related to radiochemosensitivity of HNSCC was considered for nanoString analysis based on tumour biopsies of 90 patients with locally advanced HNSCC treated by primary RCTx. Dose-volume parameters were extracted from the parotid, submandibular glands, oral cavity, larynx, buccal mucosa, and lips. Normal tissue complication probability (NTCP) models were developed for acute, late, and for the improvement of xerostomia grade ≥2 and dysphagia grade ≥3 using a cross-validation-based least absolute shrinkage and selection operator (LASSO) approach combined with stepwise logistic regression for feature selection. The final signatures were included in a logistic regression model with optimism correction. Performance was assessed by the area under the receiver operating characteristic curve (AUC). RESULTS: NTCP models for acute and late xerostomia and the improvement of dysphagia resulted in optimism-corrected AUC values of 0.84, 0.76, and 0.70, respectively. The minimum dose to the contralateral parotid was selected for both acute and late xerostomia and the minimum dose to the larynx was selected for dysphagia improvement. For the xerostomia endpoints, the following gene expressions were selected: RPA2 (cellular response to DNA damage), TCF3 (salivary gland cells development), GBE1 (glycogen storage and regulation), and MAPK3 (regulation of cellular processes). No gene expression features were selected for the prediction of dysphagia. CONCLUSION: This hypothesis-generating study showed the potential of improving NTCP models using gene expression data for HNSCC patients. The presented models require independent validation before potential application in clinical practice.

Development and validation of a 6-gene signature for the prognosis of loco-regional control in patients with HPV-negative locally advanced HNSCC treated by postoperative radio(chemo)therapy.

PURPOSE: The aim of this study was to develop and validate a novel gene signature from full-transcriptome data using machine-learning approaches to predict loco-regional control (LRC) of patients with human papilloma virus (HPV)-negative locally advanced head and neck squamous cell carcinoma (HNSCC), who received postoperative radio(chemo)therapy (PORT-C). MATERIALS AND METHODS: Gene expression analysis was performed using Affymetrix GeneChip Human Transcriptome Array 2.0 on a multicentre retrospective training cohort of 128 patients and an independent validation cohort of 114 patients from the German Cancer Consortium - Radiation Oncology Group (DKTK-ROG). Genes were filtered based on differential gene expression analyses and Cox regression. The identified gene signature was combined with clinical parameters and with previously identified genes related to stem cells and hypoxia. Technical validation was performed using nanoString technology. RESULTS: We identified a 6-gene signature consisting of four individual genes CAV1, GPX8, IGLV3-25, TGFBI, and one metagene combining the highly correlated genes INHBA and SERPINE1. This signature was prognostic for LRC on the training data (ci = 0.84) and in validation (ci = 0.63) with a significant patient stratification into two risk groups (p = 0.005). Combining the 6-gene signature with the clinical parameters T stage and tumour localisation as well as the cancer stem cell marker CD44 and the 15-gene hypoxia-associated signature improved the validation performance (ci = 0.69, p = 0.001). CONCLUSION: We have developed and validated a novel prognostic 6-gene signature for LRC of HNSCC patients with HPV-negative tumours treated by PORT-C. After successful prospective validation the signature can be part of clinical trials on the individualization of radiotherapy.

Analyses of molecular subtypes and their association to mechanisms of radioresistance in patients with HPV-negative HNSCC treated by postoperative radiochemotherapy.

PURPOSE: To assess the relation of the previously reported classification of molecular subtypes to the outcome of patients with HNSCC treated with postoperative radio(chemo)therapy (PORT-C), and to assess the association of these subtypes with gene expressions reflecting known mechanisms of radioresistance. MATERIAL AND METHODS: Gene expression analyses were performed using the GeneChip Human Transcriptome Array 2.0 on a multicentre retrospective patient cohort (N = 128) of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG) with locally advanced HNSCC treated with PORT-C. Tumours were assigned to four molecular subtypes, and correlation analyses between subtypes and clinical risk factors were performed. In addition, the classifications of eight genes or gene signatures related to mechanisms of radioresistance, which have previously shown an association with outcome of patients with HNSCC, were compared between the molecular subtypes. The endpoints loco-regional control (LRC) and overall survival (OS) were evaluated by log-rank tests and Cox regression. RESULTS: Tumours were classified into the four subtypes basal (19.5%), mesenchymal (18.8%), atypical (15.6%) and classical (14.1%). The remaining tumours could not be classified (32.0%). Tumours of the mesenchymal subtype showed a lower LRC compared to the other subtypes (p = 0.012). These tumours were associated with increased epithelial-mesenchymal transition (EMT) and overexpression of a gene signature enriched in DNA repair genes. The majority of the eight considered gene classifiers were significantly associated to LRC or OS in the whole cohort. CONCLUSION: Molecular subtypes, previously identified on HNSCC patients treated with primary radio(chemo)therapy or surgery, were related to LRC for patients treated with PORT-C, where mesenchymal tumours presented with worse prognosis. After prospective validation, subtype-based patient stratification, potentially in combination with other molecular classifiers, may be considered in future interventional studies in the context of personalised radiotherapy and may guide the development of combined treatment approaches.

Endoscopic Optical Coherence Tomography for Evaluation of Success of Tympanoplasty.

OBJECTIVE: After tympanoplasty, it is often challenging to differentiate between different causes of a remaining air bone gap (ABG). Optical coherence tomography (OCT) offers a new approach for combined morphologic and functional measurements of the tympanic membrane and adjacent parts of the middle ear. Thus, it provides valuable diagnostic information in patients with a reduced sound transfer after middle ear surgery. PATIENT AND INTERVENTION: A patient with history of tympanoplasty and a persistent ABG was investigated with endoscopic OCT before revision surgery. MAIN OUTCOME MEASURES: The oscillation behavior and the thickness of the reconstructed tympanic membrane was determined. The oscillation amplitudes of the inserted prosthesis were compared to a finite element model simulation and to the clinical findings and the audiometric data of the patient. RESULTS: OCT measurements showed a reduced oscillation amplitude of the prosthesis while revealing an aerated middle ear and good coupling of the prosthesis. Transfer loss measured by OCT showed a similar progression as the ABG measured by pure-tone audiometry with a mean divergence of 4.45 dB. CONCLUSION: Endoscopic OCT is a promising tool for the evaluation of tympanoplasty outcome. It supports established otologic diagnostics and can help differentiating between different causes of conductional hearing loss.

Interdisciplinary Comparison of Endoscopic Laser-Assisted Diverticulotomy vs. Transcervical Myotomy as a Treatment for Zenker's Diverticulum.

BACKGROUND: Currently, there are different competing techniques for the treatment of Zenker's diverticulum (ZD). To improve patient selection, we compared endoscopic laser-assisted diverticulotomy (ELAD) with transcervical myotomy (TCM) with regard to possible risk factors for treatment failure. METHODS: Data of ZD patients (n = 104) treated between 2004 and 2016 with either TCM (38%) or ELAD (62%) were analyzed retrospectively. Univariate and multivariate analyses were performed. RESULTS: TCM is associated with a higher morbidity (27.8% vs. 10.2%; p = 0.095) but lower recurrence rate (7.3% vs. 19.3%; p = 0.095). Preoperative reflux disease (OR 8.755; p = 0.021) was identified as an independent risk factor for complications. CONCLUSIONS: Although short-term outcome and symptom relief are similar, TCM tends to have a higher complication rate but better long-term results. Preoperative reflux disease is an independent risk factor for postoperative complications.

The Obliteration of Noncritical Size Bone Defects With Bone Dust or Bone Replacement Material (Bioactive Glass S53P4).

HYPOTHESIS: Bone dust (BD) harvested during operation may be suitable as an autologous obliteration material for noncritical size defects. Bioactive glass (BA) can be an alternative. BACKGROUND: To treat noncritical size defects, BD and BA are commonly used for obliteration techniques. However, the optimal harvesting method and parameters for BD have not been examined. In this study, we analyzed the osseoregenerative potential of both materials. METHODS: Thirteen female merino sheep (7-yr old) underwent surgery on the frontal calvaria. Three defects were inserted. The first defect was considered a reference and remained unfilled, the second defect was filled with BD from the calvaria bone, and the third defect was filled with BA S53P4. The animals were sacrificed after 3 weeks. To evaluate bone regeneration, we used digital volume tomography, bone density measurement, fluorochrome sequence labeling, and histological analysis. RESULTS: All analyses showed quantitative and qualitative bone regeneration 3 weeks after operation. The control blank defect showed significantly less new bone growth than the BD-filled defect. Moreover, bone regeneration occurred from the surrounding bone and showed only a defect bridge in the BD-filled defect. The BA completely filled the defect and had the highest density although the same amount of new mineralized bone generated as in the reference. CONCLUSION: BD and BA seemed to be suitable bone replacement materials for obliteration techniques because they completely filled the defects. Thus, BD harvested under standardized conditions provided a higher level of osteoreparation potential for the generation of woven bone and establishment of defect bridges.

Endoscopic optical coherence tomography with wide field-of-view for the morphological and functional assessment of the human tympanic membrane.

An endoscopic optical coherence tomography (OCT) system with a wide field-of-view of 8 mm is presented, which combines the image capability of endoscopic imaging at the middle ear with the advantages of functional OCT imaging, allowing a morphological and functional assessment of the human tympanic membrane. The endoscopic tube has a diameter of 3.5 mm and contains gradient-index optics for simultaneous forward-viewing OCT and video endoscopy. The endoscope allows the three-dimensional visualization of nearly the entire tympanic membrane. In addition, the oscillation of the tympanic membrane is measured spatially resolved and in the frequency range between 500 Hz and 5 kHz with 125 Hz resolution, which is realized by phase-resolved Doppler OCT imaging during acoustical excitation with chirp signals. The applicability of the OCT system is demonstrated in vivo. Due to the fast image acquisition, structural and functional measurements are only slightly affected by motion artifacts.

Hearing outcome after sequential cholesteatoma surgery.

The objective of this study was to assess hearing outcome after sequential cholesteatoma surgery stratified for exclusively transcanal technique (ETC), combined transcanal and transmastoidal technique (TCM) and canal wall down surgery (CWD) and to analyze the impact of ossicular reconstruction technique (partial ossicular replacement prostheses/PORP and total ossicular replacement prostheses/TORP) on hearing outcome. This study is a retrospective case review and clinical case study conducted in a tertiary referral center. Patients who underwent 376 cholesteatoma surgeries (2007-2009) and 92 ears in clinical re-examination at least 12 months postoperatively were included. Sequential cholesteatoma surgery with ETC, TCM, or CWD; ossiculoplasty with PORP or TORP were the interventions administered. Pre- and postoperative air-bone gap (ABG) and air conduction threshold (AC) for 0.5-3 kHz were the main outcome measures. Overall, the mean preoperative ABG decreased from 25.3 ± 1.3 to 19.8 ± 0.9 dB with a mean ABG closure of 5.4 ± 1.3 dB (p ≤ 0.001). According to surgical technique, the postoperative ABG after CWD 23.5 ± 2.1 was significantly worse compared to ETC (17.3 ± 1.0 dB, p < 0.05) and TCM (19.4 ± 1.3 dB). A significant ABG closure was observed after ETC (6.8 ± 2.0 dB, p < 0.01) and TCM (6.5 ± 2.0 dB, p < 0.01) contrary to CWD (2.1 ± 2.9 dB, p > 0.05). Patients receiving PORP showed a significantly less ABG postoperatively (19.0 ± 0.9 dB, p ≤ 0.05) compared to the TORP group (24.1 ± 2.5 dB). However, a significant hearing gain was assessed after PORP- (4.7 ± 1.6 dB, p ≤ 0.01) and TORP- implantation (10.4 ± 3.7 dB, p ≤ 0.01). Sequential cholesteatoma surgery allowed for an excellent hearing outcome postoperatively. An intact posterior canal wall and a present stapes suprastructure were identified to predict a significantly superior hearing result. In addition to the technical and prosthetic considerations, the audiological outcome was confounded by the attending middle ear pathology.

Health-related quality of life measurement after cholesteatoma surgery: comparison of three different surgical techniques.

The objective of this study was to compare health-related quality of life (HRQOL) after sequential cholesteatoma surgery including exclusively transcanal technique (ETC), combined transcanal transmastoidal technique (TCM) and canal wall down surgery with obliteration (CWD). It was a clinical case study conducted in a tertiary referral center. 97 patients at least 12 months after cholesteatoma surgery were included. Interventions included sequential cholesteatoma surgery with ETC, TCM or CWD; ossiculoplasty with partial and total ossicular replacement prostheses. HRQOL assessed by Chronic Otitis Media Outcome Test 15 including an overall score and three subscores ('ear symptoms', 'hearing function' and 'mental health') as well as a general evaluation of HRQOL and the frequency of physician consultations, audiometric outcome related to HRQOL were the main outcome measures. Patients, who had undergone sequential cholesteatoma surgery, showed moderate restrictions in HRQOL postoperatively. Stratified for the three surgical techniques, patients receiving ETC tended to report lower restrictions in HRQOL. The ETC group offered a significantly lower value in the subscore 'ear symptoms'. The 'hearing function' was attributed to be the most restriction criteria for all techniques. The overall score and all subscores correlated moderately with the postoperative air conduction threshold. The strongest correlation coefficient was achieved for the subscore 'hearing function' (r(s) = 0.49, p < 0.001). Sequential cholesteatoma surgery offers acceptable moderate restrictions in HRQOL postoperatively. Patients receiving canal wall down surgery with obliteration showed equivalent limitations in HRQOL compared to closed techniques (ETC, TCM). The postoperative air conduction threshold was shown not to be a sufficient indicator for HRQOL. Therefore, disease-specific validated and reliable measuring instruments for HRQOL should be transferred from clinical research to clinical practice to provide an individualized postoperative assessment after cholesteatoma surgery.

Cholesteatoma recidivism: comparison of three different surgical techniques.

OBJECTIVE: To compare cholesteatoma recidivism rates after exclusive transcanal technique (ETC), combined transcanal and mastoidal technique (TCM, both subsets of intact canal wall technique, ICW), and canal wall down surgery (CWD). STUDY DESIGN: Retrospective case review and clinical case study SETTING: Tertiary referral center. PATIENTS: 406 cholesteatoma surgeries (2007-2009), 116 ears in clinical re-examination at least 1 year postoperatively. INTERVENTION: Sequential cholesteatoma surgery with ETC, TCM, or CWD. MAIN OUTCOME MEASURES: Cholesteatoma recidivism, residual and recurrent disease, localization of recidivism, validity of clinical findings. RESULTS: Out of 406 patients, ETC was performed in 227 (56%), TCM in 122 (30%), and CWD in 57 (14%) cases. Recidivism rates after ICW (15%) and CWD (16%) were almost similar. Recidivism was more frequent after ETC (11%) than after TCM (25%). Residuals were observed in 2% after ETC, 6.5% after TCM, and 7% after CWD. Incidence of recurrent disease was 9% for ETC, 18% for TCM, and 9% for CWD. Preferred localization of recidivism was the tympanic cavity after ETC (92%) and CWD (56%) and the mastoid cavity after TCM (53%). The clinical re-examination showed no further recidivistic disease. CONCLUSIONS: Sequential surgery is an effective and successful strategy in cholesteatoma eradication, providing a similar recidivism rate compared to following cholesteatoma retrograde and resection of the posterior canal wall. Lower recidivism after ETC was observed as a consequence of limited disease and the postoperative middle ear status determined the higher rate of recurrence after TCM. Therefore, the restricted visualization of the middle ear during ICW surgery does not increase the rate of recidivism, compared with CWD, as described in other studies. Cholesteatoma recidivism is mainly attributed to the surgeon's experience that outweighs the chosen strategy.

Microsurgical skills training with a new tympanoplasty model: learning curve and motivational impact.

OBJECTIVES: To evaluate the microsurgical skills training on a tympanoplasty model with regard to the learning curve and the participants' motivation for a surgical specialty. STUDY DESIGN: Randomized controlled prospective study. SETTING: Department of Otolaryngology, Head and Neck Surgery, Medical Campus Carl Gustav Carus at the Technische Universität Dresden, Germany. SUBJECTS: Thirty randomly chosen fifth-year medical students divided into 2 groups. INTERVENTIONS: Group 2 (n = 16) had to perform an ossicular and tympanic membrane reconstruction on a tympanoplasty model on Days 1, 7, 14, and 21 and Group 1 (n = 14) on Days 1 and 21, while observing the procedure at Days 7 and 14. Six otosurgeons served as gold standard. Attempts and time of prosthesis placement and time for tympanic membrane reconstruction were recorded. Tremor frequency and amplitude were obtained at the same time points. An adjusted study interest questionnaire was used to assess students' motivation. RESULTS: Students in Group 2 showed a significant improvement in all reconstruction parameters over the study period compared with both, baseline measurement on first day and Group 1. However, the obtained learning curve did not reach the experts level. Tremor indices and students' motivation showed no correlation with the reconstruction parameters, whereas the training itself had a positive impact on students' interest in the surgical specialty. CONCLUSION: Training with the tympanoplasty model is suitable to acquire first microsurgical motor skills in otolaryngology and to arouse students' interest in the surgical field and otorhinolaryngology.

Minimally invasive anterolateral approach to the hip: risk to the superior gluteal nerve.

BACKGROUND: Minimally invasive approaches to the hip show promise of less muscle trauma compared to conventional approaches. What is the risk of damage to the superior gluteal nerve? We studied the course of the superior gluteal nerve. METHOD: 20 legs of 11 formalin-fixed Caucasian cadavers were dissected and the course and the distances of the superior gluteal nerve branches from the tip of the greater trochanter were documented. RESULTS: The branch of the gluteal superior nerve leading to the gluteal minimus muscle was 33 (20-50) mm from the tip of the greater trochanter, within a deeper layer. The nearest point of the superior gluteal nerve branches from the tip of the greater trochanter in the posterior region was 19 (10-30) mm, in the middle region 20 (20-30) mm and in the anterior region 20 (10-35) mm. In half of the cases, a distal intermuscular branch between gluteal medius and tensor fasciae latae muscle could be found, mean 27 (10-40) mm caudal and 38 (25-60) mm ventral to the tip of the greater trochanter. This distal branch is considered to create a loop with upper branches of the superior gluteal nerve within the tensor fasciae muscle. INTERPRETATION: The safe zone for the superior gluteal nerve was smaller than previously reported. Use of a minimal direct lateral approach puts the inferior branches within the gluteal medius at risk; however, a minimal anterolateral approach to the hip may compromise branches of the superior gluteal nerve to the tensor fasciae latae muscle.