Obturator Internus Research Articles

Anatomical basis for contribution of hip joint motion by the obturator internus to defaecation/urinary functions by the levator ani via the obturator fascia.

The functional association between hip joint motion and defaecation/urinary function has attracted considerable research and clinical attention owing to the potential novel approaches for pelvic floor rehabilitation; however, the anatomical basis remains unclear. This study, therefore, aimed to analyse the anatomical basis of force transmission between the obturator internus, a muscle of the hip joint, and the levator ani, a muscle of the pelvic floor. Twenty-three cadavers were used for macroscopic and histological analyses. The three-dimensional structures of the muscles and fascia were recorded using a high-definition camera and a 3D scanner. The arrangement and attachment of the muscle fibres, tendons and fascia were visualised using histological sections stained with Masson's trichrome. The obturator internus and levator ani were in broad contact through the obturator fascia. The height of their contact area was 24.6 ± 9.1 mm. Histologically, the obturator internus and levator ani shared a large area of the obturator fascia, and the obturator fascia provided the attachment of several muscle layers of the levator ani. The contribution of hip joint motion to defaecation/urinary function can be explained by the broad 'planar' contact between the obturator internus and levator ani. This anatomical feature suggests that movement of the obturator internus creates the foundation for the function of the levator ani and contributes to pelvic floor support through the obturator fascia. This study provides an anatomical basis for the effectiveness of the hip muscles in improving defaecation/urinary function by enabling balanced and proper movements.

Pelvic Venous Insufficiency: Input of Short Tau Inversion Recovery Sequence.

Objectives: To evaluate indirect criteria of pelvic venous insufficiency (PVI) of a short tau inversion recovery (STIR) sequence retrospectively compared with phlebographic findings. Methods: Between 2008 and 2018, 164 women who had received MRI and phlebography for pelvic congestion syndrome (60), varicose veins in the lower limbs (45), both (43), or other symptoms (16) were included. The presence of periuterine varicosities and perivaginal varicosities were compared to the findings of phlebography: grading of left ovarian vein reflux and presence of internal pudendal or obturator leak. Results: There was a correlation between the grading of LOV reflux on phlebography and the diameter of periuterine varicosities on STIR sequence (p = 0.008, rho = 0.206, CIrho [0.0549 to 0.349]). Periuterine varicosities had a positive predictive value of 93% for left ovarian reflux (95% CI [88.84% to 95.50%]). Obturator or internal pudendal leaks were found for 118 women (72%) and iliac insufficiency for 120 women (73%). Conclusions: Non-injected MRI offers a satisfactory exploration of PVI with STIR sequence. STIR sequences alone enabled the detection of left ovarian and iliac insufficiency.

Myofascial Pain Syndrome in Women with Primary Dysmenorrhea: A Case-Control Study.

There is limited information on myofascial trigger points (MTrPs) and specific symptoms of chronic pelvic pain and, more specifically, dysmenorrhea. The objective of this study was to determine whether patients suffering from primary dysmenorrhea present alterations in mechanosensitivity and pain patterns, and greater presence of MTrPs in the abdominal and pelvic floor muscles. A case-control study was carried out with a total sample of 84 participants distributed based on primary dysmenorrhea and contraceptive treatment. The sample was divided into four groups each comprising 21 women. Data on pain, quality of life, and productivity and work absenteeism were collected; three assessments were made in different phases of the menstrual cycle, to report data on pressure pain threshold, MTrP presence, and referred pain areas. One-way ANOVA tests showed statistically significant differences (p < 0.01) between the groups, for the Physical Health domain and the total score of the SF-12 questionnaire, and for all the domains of the McGill questionnaire; but no significant differences were found in the data from the WPAI-GH questionnaire. Statistically significant data (p < 0.01) were found for mechanosensitivity in the abdominal area and limbs, but not for the lumbar assessment, within the group, with very few significant intergroup differences. The frequency of active MTrPs is higher in the groups of women with primary dysmenorrhea and during the menstrual phase, with the prevalence of myofascial trigger points of the iliococcygeus muscle being especially high in all examination groups (>50%) and higher than 70% in women with primary dysmenorrhea, in the menstrual phase, and the internal obturator muscle (100%) in the menstrual phase. Referred pain areas of the pelvic floor muscles increase in women with primary dysmenorrhea.

Topographical anatomy of the albino rat’s ischiotrochanteric muscle group

The obturator internus, gemelli, and quadratus femoris muscles are thought to be postural muscles. Thus, they are in the focus of research. Although these muscles are described in other species, detailed descriptions are still lacking for the albino rat. We hypothesized that the rat’s ischiotrochanteric muscle group is comparable to that of humans. We aimed to provide a detailed description, and to compare the rat’s condition with other species including humans. Both hind limbs of 30 adult male formalin-fixed albino rats were carefully dissected and photo documented. Our results were then compared with data for other species and descriptions of human anatomy. The gemellus muscle was one single muscle mass, originating from the lesser sciatic notch and an unnamed groove on the dorsal aspect of the ischium. The obturator internus muscle arose from the inner aspect of the tabula of ischium. Both muscles formed a continuum and inserted as one complex on the medial aspect of the greater trochanter. The quadratus femoris muscle originated from the outer aspect of the tabula of ischium and inserted on the distal portion of the intertrochanteric crest, and the dorsal aspect of the lesser trochanter. Despite minor differences, the topographical conditions of these muscles are comparable between rats and other mammals including humans.

Combined transposition of internal obturator and superficial gluteal muscles for perineal hernia treatment in dogs: 17 cases (2017-2020).

To report the results of the combined transposition of the internal obturator muscle and superficial gluteal muscle for perineal hernia treatment in dogs. Retrospective case series of dogs treated with this technique from November 2017 to May 2020, including pre- and post-operative clinical findings, outcome and complications. Seventeen dogs were included in the study. Twelve dogs were presented with unilateral perineal hernia and five dogs with bilateral perineal hernias. Mean duration of clinical signs before presentation was 9 months. All perineal hernias were successfully repaired using a transposition of the internal obturator muscle to cover the ventral aspect of the perineal hernia and the superficial gluteal muscle to cover the dorsal aspect of the hernia with minimal tension. All dogs regained normal defecation within 24 hours post-surgery. Average follow-up time was 16 months. No recurrence of clinical signs or rectal deviation was observed. Five dogs developed a superficial minor partial necrosis of the T-shaped incision and two had surgical site infections. Perineal herniorrhaphy using a combined transposition of the internal obturator and the superficial gluteal muscles is feasible and offered excellent results in this cohort of dogs. It may be considered as a technique for repairing chronic and extensive unilateral and bilateral perineal hernias.

Muscle recovery after total hip arthroplasty: prospective MRI comparison of anterior and posterior approaches.

The direct anterior approach (DAA) and the posterior approach (PA) are 2 common total hip arthroplasty (THA) exposures. This prospective study quantitatively compared changes in periarticular muscle volume after DAA and PA THA. 19 patients undergoing THA were recruited prospectively from the practices of 3 fellowship-trained hip surgeons. Each surgeon performed a single approach, DAA or PA. Enrolled patients underwent a preoperative MRI of the affected hip and two subsequent postoperative MRIs at around 6 weeks and 6 months after surgery. Clinical evaluations were done by Harris Hip Score at each follow-up interval. MRIs or 10 DAA and 9 PA patients were analysed. Groups did not differ significantly with regard to BMI, age, or preoperative muscle volume. 1 DAA patient suffered a periprosthetic fracture and was excluded from the study. DAA hips showed significant atrophy in the obturator internus (-37.3%) muscle at early follow-up, with persistent atrophy of this muscle at the final follow-up. PA hips showed significant atrophy in the obturator internus (-46.8%) and externus (-16.0%), piriformis (-8.12%), and quadratus femoris muscles (-13.1%) at early follow-up, with persistent atrophy of these muscles at final follow-up. Loss of anterior capsular integrity was present at final follow-up in 2/10 DAA hips while loss of posterior capsular integrity was present in 5/9 PA hips. There was no difference in clinical outcomes. This study demonstrates that DAA showed less persistent muscular atrophy than PA. Regardless of surgical approach, a muscle whose tendon is detached from its insertion is likely to demonstrate persistent atrophy 6 months following THA. Although the study was not powered to compare clinical outcomes, it should be noted that no significant difference in patient outcomes was observed.

Hypothesis generation: Quantitative research to levator ani muscle injury based on MRI texture analysis.

Patients with pelvic organ prolapse (POP) mostly have injury to the levator ani muscle (LAM). We aimed to assess LAM injury in POP patients by quantifying texture feature (TF) ratios between the LAM and the obturator internus muscle (OIM) using texture analysis. This study retrospectively enrolled 32 participants, including 24 patients with POP and eight people with normal pelvic floor muscles. TFs of the LAM and the OIM were extracted using LIFEx version 6.30, and an independent samples t-test was performed to determine TF ratios characterizing LAM injury. After dimension reduction and binary logic analysis, the optimal TF ratio was obtained and the LAM injury quantitative evaluation was proposed. Spearman's correlation was performed to explore the correlations between TF ratios and clinical characteristics. We compared the diagnostic performance of quantitative evaluation and visual evaluation. There were significant differences in 13 TF ratios between the POP and control groups. The area under the receiver operating characteristic curve of the integrated TF ratio was 0.948. Integrated TF ratio was significantly correlated with body mass index, pregnancies, and vaginal deliveries but had no correlation with LAM volume, hiatal area or abortions. Compared with the visual evaluation, the diagnostic accuracy of the quantitative evaluation had improved by 63.2% and 14.3% in the "minor defect" and "major defect" categories, respectively. The integrated TF ratio can be used as a new quantifiable index to characterize LAM injury. The TF evaluation provides a potential role in LAM injury noninvasive diagnostic.

Automatic segmentation of prostate and extracapsular structures in MRI to predict needle deflection in percutaneous prostate intervention.

Understanding the three-dimensional anatomy of percutaneous intervention in prostate cancer is essential to avoid complications. Recently, attempts have been made to use machine learning to automate the segmentation of functional structures such as the prostate gland, rectum, and bladder. However, a paucity of material is available to segment extracapsular structures that are known to cause needle deflection during percutaneous interventions. This research aims to explore the feasibility of the automatic segmentation of prostate and extracapsular structures to predict needle deflection. Using pelvic magnetic resonance imagings (MRIs), 3D U-Net was trained and optimized for the prostate and extracapsular structures (bladder, rectum, pubic bone, pelvic diaphragm muscle, bulbospongiosus muscle, bull of the penis, ischiocavernosus muscle, crus of the penis, transverse perineal muscle, obturator internus muscle, and seminal vesicle). The segmentation accuracy was validated by putting intra-procedural MRIs into the 3D U-Net to segment the prostate and extracapsular structures in the image. Then, the segmented structures were used to predict deflected needle path in in-bore MRI-guided biopsy using a model-based approach. The 3D U-Net yielded Dice scores to parenchymal organs (0.61-0.83), such as prostate, bladder, rectum, bulb of the penis, crus of the penis, but lower in muscle structures (0.03-0.31), except and obturator internus muscle (0.71). The 3D U-Net showed higher Dice scores for functional structures ([Formula: see text]0.001) and complication-related structures ([Formula: see text]0.001). The segmentation of extracapsular anatomies helped to predict the deflected needle path in MRI-guided prostate interventions of the prostate with the accuracy of 0.9 to 4.9 mm. Our segmentation method using 3D U-Net provided an accurate anatomical understanding of the prostate and extracapsular structures. In addition, our method was suitable for segmenting functional and complication-related structures. Finally, 3D images of the prostate and extracapsular structures could simulate the needle pathway to predict needle deflections.

An Acute Hip Injury Correlated With An Exacerbation Of Urinary Symptoms In A Dancer

HISTORY23-year-old female dancer sustained an acute right hip/groin injury during a rond-de-jambe movement (requiring a combination of hip abduction, extension and external rotation). She had a sensation of a pop at the time of injury, followed by difficulty with external rotation as she attempted to continue to dance. Subsequent days were characterized by bruising to the inner groin and progressive medial thigh discomfort. She concurrently experienced a significant worsening of pre-existing urinary dysfunction characterized by episodes of urge incontinence and a sensation of incomplete voiding. She then developed secondary lateral hip, sacroiliac and low back discomfort. PHYSICAL EXAMShe presented to our office 6 weeks after the initial injury. She had a normal gait and symmetric hip range of motion. Right hip exam with pain at end range of passive hip flexion, and pain also with resisted testing of hip adduction, internal rotation and external rotation. She had tenderness over the anterior hip flexor tendons and at the proximal medial thigh just inferior to the pubic ramus. She was not tender to the pubic ramus. Thomas test was negative bilaterally, but she had significant tightness of quadriceps bilaterally noted on Ely’s test. An internal exam separately completed by her urogynecologist identified tightness of the pelvic floor musculature. DIFFERENTIAL DIAGNOSIS adductor muscle strain, strain of deep hip rotator muscles (obturator externus, obturator internus), hip flexor tendonitis (as primary or secondary diagnosis), labral tear, pelvic floor muscle strain/tear/dysfunction, primary or secondary tightness of pelvic floor musculature, hormonal and/or bladder irritants affecting urinary function TESTS AND RESULTS 1. Xray pelvis/hip series: Well-formed acetabula, slight predisposition to CAM type FAI 2. Hip MRI: Shallow right acetabulum with mild uncovering of lateral femoral head, signs of possible labral tear, small partial intramuscular tear of the R obturator externus, strain of R iliopsoas muscle 3. Dynamic hip ultrasound - pending FINAL WORKING DIAGNOSIS 1.Obturator externus strain with comorbid strain of iliopsoas muscle 2.Pelvic floor dysfunction TREATMENT AND OUTCOMES 1. Dance specific PT for core and peri-pelvic stabilization 2. Pelvic floor physical therapy 3. Gradual return to dance

Effective dissecting range and prognostic significance of lateral pelvic lymph node dissection for middle-low rectal cancer patients with lateral pelvic lymph node metastasis: Results of a large multicenter lateral node collaborative group in China.

BackgroundLateral pelvic lymph node (LPN) metastasis causes increased lateral local recurrence and poor prognosis. We aimed to investigate the prognostic significance and effective range of dissection for the LPN dissection (LPND) in rectal cancer patients with LPN metastasis.Materials and methodsThrough this large, multicenter retrospective cohort study, we evaluated the therapeutic effect of LPND. From January 2012 to December 2019, 387 rectal cancer patients with clinical evidence of LPN metastasis who underwent total mesorectal excision with LPND were included in the study. According to pathological findings, they were divided into negative (n = 296) and positive (n = 91) LPN groups. Primary endpoints were 3-year overall survival (OS), recurrence-free survival (RFS), and local recurrence-free survival (LRFS).ResultsThe OS, RFS, and LRFS in the positive group were significantly worse than those in the negative group; However, LPN metastases were not independent prognostic risk factors for LRFS (hazard ratio [HR]: 2.42; 95% confidence interval [CI], 0.77–7.64; P=0.132). Among patients with pathological LPN metastases, LPN metastases to the common and external iliac arteries were independent prognostic risk factors both for OS (HR: 4.74; 95% CI, 1.74–12.90; P=0.002) and RFS (HR: 2.70; 95% CI, 1.16–6.29; P=0.021). No significant difference was observed in the 3-year OS (72.3% vs. 70.2%, P=0.775) and RFS rates (60.9% vs. 52.6%, P=0.408) between patients with metastases to the obturator or internal iliac arteries and patients at N2b stage.ConclusionsLPND may be effective in controlling local recurrence in patients with LPN metastasis but not systemic metastases. Patients with LPN metastasis limited to the internal iliac and obturator regions achieve a long-term survival benefit from LPND, and their prognoses may be comparable to those at the N2b stage. Further metastasis to the external iliac or common iliac region should be considered systemic disease, and LPND should be avoided.Clinical Trial Registration ClinicalTrials.gov, identifier NCT04850027.

Relationship between high intra-abdominal pressure and compliance of the pelvic floor support system in women without pelvic organ prolapse: A finite element analysis.

Previous studies mainly focused on the relationship between the size of the prolapse and injury to the supporting tissues, but the strain and stress distributions of the supporting tissues as well as high-risk areas of injury are still unknown. To further investigate the effect of supporting tissues on organs and the interactions between organs, this study focused on the relationship between high intra-abdominal pressure and the compliance of the pelvic floor support system in a normal woman without pelvic organ prolapse (POP), using a finite element model of the whole pelvic support system. A healthy female volunteer (55 years old) was scanned using magnetic resonance imaging (MRI) during rest and Valsalva maneuver. According to the pelvic structure contours traced by a gynecologist and anatomic details measured from dynamic MRI, a finite element model of the whole pelvic support system was established, including the uterus, vagina with cavity, cardinal and uterosacral ligaments, levator ani muscle, rectum, bladder, perineal body, pelvis, and obturator internus and coccygeal muscles. This model was imported into ANSYS software, and an implicit iterative method was employed to simulate the biomechanical response with increasing intra-abdominal pressure. Stress and strain distributions of the vaginal wall showed that the posterior wall was more stable than the anterior wall under high intra-abdominal pressure. Displacement at the top of the vagina was larger than that at the bottom, especially in the anterior–posterior direction. These results imply potential injury areas with high intra-abdominal pressure in non-prolapsed women, and provide insight into clinical managements for the prevention and surgical repair plans of POP.

The use of a modified posterior approach (SPAIRE) may be associated with an increase in return to pre-injury level of mobility compared to a standard lateral approach in hemiarthroplasty for displaced intracapsular hip fractures: a single-centre study of the first 285 cases over a period of 3.5 years

Background and purposeA tendon-sparing modification of the posterior approach to the hip joint was introduced in the specialist hip unit at our institution in 2016. The SPAIRE technique—acronym for “Saving Piriformis And Internus, Repair of Externus” preserves the insertions of gemellus inferior, obturator internus, gemellus superior and piriformis intact. We compare the results of the first 285 hip hemiarthroplasty patients, unselected but preferentially treated by our hip unit surgeons using the SPAIRE technique, with 567 patients treated by all orthopaedic surgeons (including the hip unit) in the department over the same 3.5 year period using the standard lateral approach. We report length of stay, return to pre-injury level of mobility, place of residence and mortality at 120 days.Patients and methodsThe review included all hemiarthroplasty patients. Pre-fracture mobility and place of residence, surgical approach, grade of senior surgeon in theatre, stem modularity, acute and overall length of stay, mobility, place of residence, re-operations and mortality at 120 days were recorded. Data were obtained from the National Hip Fracture Database that included a telephone follow-up at 120 days and from electronic patient records.ResultsThe odds of returning to pre-injury level of mobility were higher in the SPAIRE technique group than in the standard lateral group; adjusted odds ratio (95% confidence interval (CI)) 1.7 (1.1 to 2.7, p = 0.01).InterpretationWhen used in hip hemiarthroplasty, the SPAIRE technique appears safe and may confer benefit in maintaining the pre-injury level of mobility over the standard lateral approach.

Outcome of surgical treatment of perineal hernia in cats: 36 cases (2013-2019).

To report the clinical presentation, complications, and long-term outcomes of cats treated for perineal hernia with modified internal obturator muscle transposition. The medical records of cats surgically treated for perineal hernia between 2013 and 2019 were reviewed and an owner questionnaire was conducted to determine long-term outcome. Thirty-six cats were included in the study: 34 had bilateral and two unilateral hernias. Of these 36, 24 (67%) were male neutered with a median age of 10 (range: 1 to 18) years. The complication rate was low, however, one cat experienced a major postoperative complication: rectal prolapse requiring revision surgery 48 hours postsurgery. Short-term outcomes were available for 32 of 36 (89%) cats. Of the 32, 23 were examined 6 weeks postoperatively, and a telephonic consultation was performed for an additional nine of 32. Of the 23 cats examined directly, none had recurrence. Overall 12 of 32 experienced short-term postoperative tenesmus which resolved in nine of 12 (75%). Long-term outcomes were available for 31 of 36 cats (86%), with a median of 18.5 (6 to 89) months follow-up. A good outcome was achieved in 23 of 31 (74%) whereas three of 31 (10%) had fair outcomes and five of 31 (16%) had a poor outcome. Of the five cats with a poor outcome, two required subtotal colectomy to manage clinical signs related to megacolon, two were euthanised following a return of clinical signs, and one developed unilateral recurrence. Perineal hernia should be considered in cats presenting with tenesmus or recurrent obstipation. Surgical treatment of perineal hernias in cats can result in good owner-assessed long-term outcome.

The ‘prostate-muscle index’: a simple pelvic cavity measurement predicting estimated blood loss and console time in robot-assisted radical prostatectomy

This study was to show the impact of ‘prostate-muscle index (PMI)’, which we developed as a novel pelvic cavity measurement, in patients undergoing robot-assisted radical prostatectomy (RARP). We defined PMI as the ‘distance between the inner edge of the obturator internus muscle and the lateral edge of the prostate at the magnetic resonance imaging (MRI) slice showing the maximum width of the prostate’. Seven hundred sixty patients underwent RARP at the University of Tokyo Hospital from November 2011 to December 2018. MRI results were unavailable in 111 patients. In total, 649 patients were eligible for this study. Median values of blood loss and console time were 300 mL and 168 min. In multivariate analysis, body mass index (BMI), prostate volume-to-pelvic cavity index (PV-to-PCI), PMI, and surgical experience were significantly associated with blood loss > 300 mL (P = 0.0002, 0.002, < 0.0001, and 0.006 respectively). Additionally, BMI, PMI, and surgical experience were also significantly associated with console time > 160 min in multivariate analysis (P = 0.04, 0.004, and < 0.0001, respectively). In conclusion, PMI may provide useful information to surgeons and patients in preoperative decision-making.

Electromyography measurements of the deep hip muscles do not improve estimates of hip contact force

The deep hip muscles are often omitted in studies investigating hip contact forces using neuromusculoskeletal modelling methods. However, recent evidence indicates the deep hip muscles have potential to change the direction of hip contact force and could have relevance for hip contact loading estimates. Further, it is not known whether deep hip muscle excitation patterns can be accurately estimated using neuromusculoskeletal modelling or require measurement (through invasive and time-consuming methods) to inform models used to estimate hip contact forces. We calculated hip contact forces during walking, squatting, and squat-jumping for 17 participants using electromyography (EMG)-informed neuromusculoskeletal modelling with (informed) and without (synthesized) intramuscular EMG for the deep hip muscles (piriformis, obturator internus, quadratus femoris). Hip contact force magnitude and direction, calculated as the angle between hip contact force and vector from femoral head to acetabular center, were compared between configurations using a paired t-test deployed through statistical parametric mapping (P < 0.05). Additionally, root mean square error, correlation coefficients (R2), and timing accuracy between measured and modelled deep hip muscle excitation patterns were computed. No significant between-configuration differences in hip contact force magnitude or direction were found for any task. However, the synthesized method poorly predicted (R2-range 0.02–0.3) deep hip muscle excitation patterns for all tasks. Consequently, intramuscular EMG of the deep hip muscles may be unnecessary when estimating hip contact force magnitude or direction using EMG-informed neuromusculoskeletal modelling, though is likely essential for investigations of deep hip muscle function.

Anterior-Based Muscle-Sparing (ABMS) Approach for Total Hip Arthroplasty.

The procedure is performed with the patient in the supine position. A minimally invasive Watson-Jones approach is utilized to access the hip. Fluoroscopy can be utilized intraoperatively to assess acetabular cup position, version, and inclination. Femoral canal fill and leg lengths can also be assessed with use of fluoroscopy. Nonoperative alternatives for the treatment of hip osteoarthritis include nonsteroidal anti-inflammatory drugs, physical therapy, and corticosteroid injections into the hip joint. Surgical alternatives to this procedure include the posterior approach (Moore or Southern), the direct lateral approach (Hardinge), and the direct anterior approach (Smith-Petersen). The Watson-Jones approach can also be performed with the patient in the lateral decubitus position (unlike in our technique where the patient is supine). The anterolateral (Watson-Jones) approach to the hip has been shown to be superior to the historically more common posterior approach with regard to length of hospital stay and dislocation risk1,2. Supine positioning for this approach offers multiple advantages compared with lateral decubitus positioning. Leg lengths can be assessed intraoperatively both fluoroscopically and with manual palpation of the medial malleoli. Cup position can be assessed radiographically as well3. Supine positioning also allows for easily reproducible patient positioning. Compared with the historically common posterior approach to the hip for THA, the anterolateral approach to the hip leads to, on average, a lower risk of hip dislocation1,2. In a 2002 study by Masonis and Bourne, the dislocation rate for the posterior approach was 3.23% (193 of 5,981), whereas the dislocation rate was 2.18% (18 of 826) for patients who underwent THA via the anterolateral approach1. In a study by Ritter et al. in 2001, which followed patients for 1 year postoperatively, no patients in the anterolateral approach group experienced a dislocation compared with 4.21% of patients in the posterior approach group2. With use of the present technique, patients will benefit from the advantages of the anterolateral approach to the hip; however, they will also benefit from easy intraoperative leg length assessment and from radiographic assistance with regard to determining the appropriate position of the femoral and acetabular components3. In a study of 199 patients (including 98 patients who had intraoperative fluoroscopy and 101 who did not), 80% of implants in the fluoroscopy group were within the combined safe zone compared with 63% in the non-fluoroscopy group. However, this approach is not without its limitations. As mentioned in the above studies, dislocation remains a possible complication of the procedure, and a minimally invasive anterior-based approach can lead to intraoperative femoral fractures when exposure and releases are inadequate4. Femoral nerve palsies are also possible with excessive medial retraction during acetabular exposure. Additionally, the benefit of a reduction in the incidence of hip dislocation compared with a posterior approach might be overstated given improvement in posterior-approach dislocation rates if posterior soft-tissue repair is used5. Both direct anterior and anterolateral approaches have the same risks of fracture with poor exposure and of neurapraxia with excessive retraction, and there does not appear to be any difference in dislocation risk between these 2 approaches6. Although a pannus is more detrimental to a direct anterior approach, it could overlie the desired incision in the ABMS approach as well. The pannus could be held out of the field by taping it to the contralateral shoulder before preparing and draping.The preparative process is more time-consuming because both legs must be sterile for this procedure.Acetabular exposure often requires an assistant standing on the contralateral side of the table.Although not often needed, the obturator internus and gemelli might need to be released in order to ensure adequate exposure of the femur.If femoral canal exposure is still insufficient, a femoral suspension hook system might be needed. ASIS = anterior superior iliac spineTFL = tensor fasciae lataeITB = iliotibial bandPOD = postoperative dayIV = intravenousBID = twice daily.

The short external rotators in the anterior approach hip arthroplasty: do the tendons heal or not? A prospective MRI study.

Release of some of the short external rotator tendons may be needed in the direct anterior approach (DAA) for Total Hip Arthroplasty (THA). It is unknown if these tendons heal. The purpose of this prospective study is to examine short external rotator tendon healing after release and the associated effect on muscle volume. In addition, we examined the relation with external rotation force and patient reported outcome measures (PROMs). In 21 DAA THA patients, preoperative MRI was compared with postoperative MRI at 6 weeks and 12 months. PROMs and rotation force of both hips were assessed. Tendon integrity and muscle volume of the obturator internus and piriformis were assessed on MRI using dedicated software. In 5 patients all tendons remained intact, in 4 patients only the conjoined tendon was released and in 12 patients both the conjoined and piriformis were released. Obturator externus remained intact in all patients. In patients with tendon release, mean volume of obturator internus and piriformis muscle decreased 27% (SD 11) and 23% (SD 16) 6 weeks after surgery, respectively. Released tendons and muscle volume loss did not recover 12 months after surgery. We found no relation between tendon release and hip rotation force or PROMs. We found absent tendon healing and muscle volume loss when the conjoined or piriformis tendons were released. Although we found no relation between tendon detachment and hip force or PROMs, we have adapted our operative technique to make it more preserving for the piriformis.

MRI assessment of minimally invasive anterolateral approaches in total hip arthroplasty

IntroductionTotal hip arthroplasty (THA) on a minimally invasive anterolateral (MIAL) approach frequently leads to gluteus minimus and gluteus medius lesions, and sometimes to tensor fasciae latae (TFL) denervation. We therefore developed compensatory strategies, which we assessed on pre- and post-operative MRI: 1) to assess gluteus minimus and gluteus medius fatty infiltration (FI), 2) to assess TFL FI, and 3) to assess FI in the other periarticular muscles. HypothesisThe modified MIAL approach reduces the rate of gluteus minimus and gluteus medius lesion. Materials and methodsA continuous prospective single-surgeon series of THA using a MIAL approach included 25 patients. Femoral implantation was performed with the hip in extension so as to distance the proximal femur from the gluteals, avoiding muscle trauma. The superior gluteal nerve branch in the space between the gluteus medius and TFL, running toward the TFL, was systematically released and protected. MRI was performed preoperatively and at 3 months and 1 year post-surgery. FI was analyzed according to the Goutallier classification in all periarticular muscles. ResultsOne patient lacked preoperative MRI and was excluded, leaving 24 patients, for 72 MRIs. In 10/24 patients (41.7%) the gluteus minimus and in 8/24 patients (33.3%) the anterior third of the gluteus medius showed ≥2 grade increase in FI between preoperative and 1-year MRI, with significant increases in both at 3 months (p<0.001) and 1 year (p<0.001). At least a 2 grade increase in FI at 1 year was seen in 1 patient (4.2%) in the TFL, in 2 (8.3%) in the piriformis, and in 1 (4.2%) in the obturator internus. There were no significant differences in FI between preoperative, 3-month or 1-year MRI in any other periarticular muscles. ConclusionFemoral implantation in hip extension did not reduce the rate of gluteal lesions, which remained frequent. In contrast, release of the superior gluteal nerve branch could be effective in conserving TFL innervation. Some rare lesions of the proximal part of the pelvi-trochanteric muscles were also observed. Level of evidenceIV, Prospective case series.

Comparative MRI assessment of three minimally invasive approaches in total hip arthroplasty

IntroductionMinimally invasive approaches (direct anterior approach: DAA; minimally invasive anterolateral: MIAL; piriformis-sparing posterior approach: PSPA) are widely used for total hip arthroplasty (THA), with a muscle-sparing objective. There are no published comparative studies of muscle damage secondary to these approaches. The aim of the present study was to compare fatty infiltration (FI) on MRI induced by DAA, MIAL and PSPA in THA 1) in the tensor fasciae latae (TFL) and sartorius muscles, 2) in the gluteal muscles, and 3) in the pelvitrochanteric muscles. HypothesisGreater FI is induced by DAA in anterior muscles, by MIAL in gluteal muscles and by PSPA in pelvitrochanteric muscles. Materials and methodsThree continuous prospective series of THA by DAA, MIAL and PSPA included 25 patients each. MRI was performed preoperatively and at 1 year postoperatively. FI was graded on the Goutallier classification in all periarticular hip muscles. Muscles showing ≥2 grade aggravation at 1 year were considered damaged. ResultsNine patients whose preoperative MRI was uninterpretable were excluded. In all, 66 patients (21 DAA, 24 MIAL and 21 PSPA) with 132 MRI scans were analyzed. TFL was damaged in 2/21 DAA patients (9.5%), 1/24 MIAL patients (4.2%) and 0/21 PSPA patients (0%). There were no sartorius lesions. The anterior third of the gluteus medius was damaged in 8/24 MIAL patients (33.3%) and the gluteus minimus in 10/24 (41.7%), compared to 1/21 DAA patients (4.8%) and 0/21 PSPA patients (0%). The mid and posterior thirds of the gluteus medius and the gluteus maximus were never damaged. The piriformis muscle was damaged in 3/21 DAA patients (14.3%), 2/24 MIAL patients (8.3%) and 2/21 PSPA patients (9.5%). The obturator internus was damaged in 4/21 DAA patients (19%), 1/24 MIAL patients (4.2%) and 16/21 PSPA patients (76.2%). The obturator externus and quadratus femoris were mainly damaged in PSPA patients: respectively, 5/21 (23.8%) and 4/21 patients (19%)). ConclusionThe muscle-sparing properties of minimally invasive hip approaches are only theoretical. In the present series, there were rare TFL lesions with DAA and MIAL. Gluteus medius and minimus lesions were frequent in MIAL. Pelvitrochanteric muscles lesions were more frequent in PSPA, but found in all 3 approaches. These findings should help guide surgeons in their choice of approach and in informing patients about the damage these minimally invasive approaches can cause. Level of evidenceIII, prospective comparative study.

Dynamic Contrast Enhanced Study in Multiparametric Examination of the Prostate-Can We Make Better Use of It?

We sought to investigate whether quantitative parameters from a dynamic contrast-enhanced study can be used to differentiate cancer from normal tissue and to determine a cut-off value of specific parameters that can predict malignancy more accurately, compared to the obturator internus muscle as a reference tissue. This retrospective study included 56 patients with biopsy proven prostate cancer (PCa) after multiparametric magnetic resonance imaging (mpMRI), with a total of 70 lesions; 39 were located in the peripheral zone, and 31 in the transition zone. The quantitative parameters for all patients were calculated in the detected lesion, morphologically normal prostate tissue and the obturator internus muscle. Increase in the Ktrans value was determined in lesion-to-muscle ratio by 3.974368, which is a cut-off value to differentiate between prostate cancer and normal prostate tissue, with specificity of 72.86% and sensitivity of 91.43%. We introduced a model to detect prostate cancer that combines Ktrans lesion-to-muscle ratio value and iAUC lesion-to-muscle ratio value, which is of higher accuracy compared to individual variables. Based on this model, we identified the optimal cut-off value with 100% sensitivity and 64.28% specificity. The use of quantitative DCE pharmacokinetic parameters compared to the obturator internus muscle as reference tissue leads to higher diagnostic accuracy for prostate cancer detection.