Aims. A revision for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) has a major effect on the patient’s quality of life, including walking capacity. The objective of this case control study was to investigate the histological and ultrastructural changes to the gluteus medius tendon (GMED) in patients revised due to a PJI, and to compare it with revision THAs without infection performed using the same lateral approach. Methods. A group of eight patients revised due to a PJI with a previous lateral approach was compared with a group of 21 revised THAs without infection, performed using the same approach. The primary variables of the study were the fibril diameter, as seen in transmission electron microscopy (TEM), and the total degeneration score (TDS), as seen under the light microscope. An analysis of bacteriology, classification of infection, and antibiotic treatment was also performed. Results. Biopsy samples from the GMED from infected patients revealed a larger fibril diameter than control patients, as seen in the TEM (p < 0.001). Uninfected patients were slightly older and had their revisions performed significantly later than the infected patients. Histologically, samples from infected patients revealed significantly more vascularity (p < 0.001), the presence of glycosaminoglycans (p < 0.001), and a higher TDS (p = 0.003) than the control patients. The majority of patients had staphylococcal infections of various species. Conclusion. More histological degeneration in the GMED was found in patients undergoing THA revision surgery due to PJI than in patients undergoing THA revision surgery due to other reasons. Cite this article: Bone Jt Open 2023;4(8):628–635

Aims. Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip centre of rotation (COR) on postoperative dislocation using a CT-based 3D model, as well as other potential risk factors for dislocation. Methods. A total of 122 patients who underwent reconstruction following resection of periacetabular tumour between January 2011 and January 2020 were studied. The risk factors for dislocation were investigated with univariate and multivariate logistic regression analysis on patient-specific, resection-specific, and reconstruction-specific variables. Results. The dislocation rate was 13.9% (n = 17). The hip COR was found to be significantly shifted anteriorly and inferiorly in most patients in the dislocation group compared with the non-dislocation group. Three independent risk factors were found to be related to dislocation: resection of gluteus medius (odds ratio (OR) 3.68 (95% confidence interval (CI) 1.24 to 19.70); p = 0.039), vertical shift of COR > 18 mm (OR 24.8 (95% CI 6.23 to 128.00); p = 0.001), and sagittal shift of COR > 20 mm (OR 6.22 (95% CI 1.33 to 32.2); p = 0.026). Conclusion. Among the 17 patients who dislocated, 70.3% (n = 12) were anterior dislocations. Three independent risk factors were identified, suggesting the importance of proper restoration of the COR and the role of the gluteus medius in maintaining hip joint stability. Cite this article: Bone Joint J 2022;104-B(10):1180–1188

Aims. The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system. Methods. This study included 30 CO THAs versus 30 RO THAs performed by a single surgeon. Intraoperative photographs of the osseous acetabulum and periacetabular soft-tissues were obtained prior to implantation of the acetabular component, which were used to develop the proposed classification system. Interobserver and intraobserver variabilities of the proposed classification system were assessed. Results. The BOne trauma and Soft-Tissue Injury classification system in total Hip arthroplasty (BOSTI Hip) grades osseous acetabular trauma and periarticular muscle damage during THA. The classification system has an interclass correlation coefficient of 0.90 (95% CI 0.86 to 0.93) for interobserver agreement and 0.89 (95% CI 0.84 to 0.93) for intraobserver agreement. RO THA was associated with improved BOSTI Hip scores (p = 0.002) and more pristine osseous surfaces in the anterior superior (p = 0.001) and posterior superior (p < 0.001) acetabular quadrants compared with CO THA. There were no differences between the groups in relation to injury to the gluteus medius (p = 0.084), obturator internus (p = 0.241), piriformis (p = 0.081), superior gamellus (p = 0.116), inferior gamellus (p = 0.132), quadratus femoris (p = 0.208), and vastus lateralis (p = 0.135), but overall combined muscle injury was reduced in RO THA compared with CO THA (p = 0.023). Discussion. The proposed BOSTI Hip classification provides a reproducible grading system for stratifying iatrogenic bone trauma and soft-tissue injury during THA. RO THA was associated with improved BOSTI Hip scores, more pristine osseous acetabular surfaces, and reduced combined periarticular muscle injury compared with CO THA. Further research is required to understand if these intraoperative findings translate to differences in clinical outcomes between the treatment groups. Cite this article: Bone Joint J 2024;106-B(9):898–906

Aims. The aims of this study were to assess the exposure and preservation of the abductor mechanism during primary total hip arthroplasty (THA) using the posterior approach, and to evaluate gluteus maximus transfer to restore abductor function of chronically avulsed gluteus medius and minimus. Patients and Methods. A total of 519 patients (525 hips) underwent primary THA using the posterior approach, between 2009 and 2013. The patients were reviewed preoperatively and at two and five years postoperatively. Three patients had mild acute laceration of the gluteus medius caused by retraction. A total of 54 patients had mild chronic damage to the tendon (not caused by exposure), which was repaired with sutures through drill holes in the greater trochanter. A total of 41 patients had severe damage with major avulsion of the gluteus medius and minimus muscles, which was repaired with sutures through bone and a gluteus maximus flap transfer to the greater trochanter. Results. Abductor strength was maintained in the normal hips, but lateral hip pain progressed significantly, five years postoperatively (p < 0.0001). In the 54 patients with mild abductor tendon damage treated with simple repair, lateral hip pain also increased significantly during follow-up (p = 0.002). In the 35 patients with severe avulsion but good muscle repaired using a gluteus maximus flap transfer, abductor function was restored. The six patients with complete avulsion and poor muscle did not regain strong abductor power, but lateral hip pain decreased. Conclusion. The posterior approach offered excellent exposure and preservation of the abductor mechanism during primary THA. Augmentation of the repair with a gluteus maximus flap provided stable reconstruction of the abductor muscles and seemed to restore function in the hips with functioning muscles. Cite this article: Bone Joint J 2019;101-B(6 Supple B):116–122

We investigated the detailed anatomy of the gluteus maximus, gluteus medius and gluteus minimus and their neurovascular supply in 22 hips in 11 embalmed adult Caucasian human cadavers. This led to the development of a surgical technique for an extended posterior approach to the hip and pelvis that exposes the supra-acetabular ilium and preserves the glutei during revision hip surgery. Proximal to distal mobilisation of the gluteus medius from the posterior gluteal line permits exposure and mobilisation of the superior gluteal neurovascular bundle between the sciatic notch and the entrance to the gluteus medius, enabling a wider exposure of the supra-acetabular ilium. This technique was subsequently used in nine patients undergoing revision total hip replacement involving the reconstruction of nine Paprosky 3B acetabular defects, five of which had pelvic discontinuity. Intra-operative electromyography showed that the innervation of the gluteal muscles was not affected by surgery. Clinical follow-up demonstrated good hip abduction function in all patients. These results were compared with those of a matched cohort treated through a Kocher–Langenbeck approach. Our modified approach maximises the exposure of the ilium above the sciatic notch while protecting the gluteal muscles and their neurovascular bundle. Cite this article: Bone Joint J 2014;96-B:48–53

We dissected 20 cadaver hips in order to investigate the anatomy and excursion of the trochanteric muscles in relation to the posterior approach for total hip replacement. String models of each muscle were created and their excursion measured while the femur was moved between its anatomical position and the dislocated position. The position of the hip was determined by computer navigation. In contrast to previous studies which showed a separate insertion of piriformis and obturator internus, our findings indicated that piriformis inserted onto the superior and anterior margins of the greater trochanter through a conjoint tendon with obturator internus, and had connections to gluteus medius posteriorly. Division of these connections allowed lateral mobilisation of gluteus medius with minimal retraction. Analysis of the excursion of these muscles revealed that positioning the thigh for preparation of the femur through this approach elongated piriformis to a maximum of 182%, obturator internus to 185% and obturator externus to 220% of their resting lengths, which are above the thresholds for rupture of these muscles. Our findings suggested that gluteus medius may be protected from overstretching by release of its connection with the conjoint tendon. In addition, failure to detach piriformis or the obturators during a posterior approach for total hip replacement could potentially produce damage to these muscles because of over-stretching, obturator externus being the most vulnerable

Abstract. Objectives. Acute compartment syndrome (ACS) is a progressive form of muscle ischaemia that is a surgical emergency and can have detrimental outcomes for patients if not treated optimally. The current problem is that there is no clear diagnostic threshold for ACS or guidance as to when fasciotomies should be performed. A new diagnostic method(s) is necessary to provide real-time information about the extent of muscle ischaemia in ACS. Given that lactic acid is produced by cells through anaerobic respiration, it may be possible to measure H+ ion concentration and to use this as a measure of ischaemia within muscle. Although we are familiar with the key biochemical metabolites involved in ischaemia; and the use of viability dyes in cell culture to distinguish between living or dead cells is well recognised; research has not been undertaken to correlate the biochemical and histological findings of ischaemia in skeletal muscle biopsies. Our primary aim was to investigate the potential for viability dyes to be used on live skeletal muscle biopsies (explants). Our secondary aim was to correlate the intramuscular pH readings with muscle biopsy viability. Methods. Nine euthanised Wistar rats were used. A pH catheter was inserted into one exposed gluteus medius muscles to record real-time pH levels and muscle biopsies were taken from the contralateral gluteus medius at the start of experiment and subsequently at every 0.1 of pH unit drop. Prior to muscle biopsy, the surface of the gluteus medius was painted with a layer of 50µmol/l Brilliant blue FCF solution to facilitate biopsy orientation. A 4mm punch biopsy tool was used to take biopsies. Each muscle biopsy was placed in a base mould filled with 4% ultra-low melting point agarose. The agarose embedded tissue block was sectioned to generate 400 micron thick tissue slices with a vibratome. The tissue slices were then placed in the staining solution with Hoechst 33342, Ethidium homodimer-1 and Calcein am. The tissue slices were imaged with Zeiss LSM880 confocal microscope's Z stack function. A dead muscle control was created by adding TritonX-100 to other tissue slices. For quantitative analyses, the images were analysed in Image J using the selection tool. This permitted individual cells to be identified and the mean grey value of each channel to be defined. Using the dead control, we were able to identify the threshold value for living cells using the Calcein AM channel. Results. Viability dyes, used primarily for cell cultures, can be used with skeletal muscle explants. Our study also showed that despite a significant reduction in tissue pH concentration over time, that almost 100% of muscle cells were still viable at pH 6.0, suggesting that skeletal muscle cells are robust to hypoxic insult in the absence of reperfusion. Conclusions. Viability dyes can be used on skeletal muscle biopsies. Further research investigating the likely associations between direct measured pH using a pH catheter, the concentrations of key cellular metabolic markers, and muscle tissue histology using vitality dyes in response to ischaemia, rather than hypoxia, is warranted. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Intact abductors of the hip play a crucial role in preventing limping and are known to be damaged through the direct lateral approach. The extent of trauma to the abductors after revision total hip replacement (THR) is unknown. The aim of this prospective study was to compare the pre- and post-operative status of the gluteus medius muscle after revision THR. We prospectively compared changes in the muscle and limping in 30 patients who were awaiting aseptic revision THR and 15 patients undergoing primary THR. The direct lateral approach as described by Hardinge was used for all patients. MRI scans of the gluteus medius and functional analyses were recorded pre-operatively and six months post-operatively. The overall mean fatty degeneration of the gluteus medius increased from 35.8% (1.1 to 98.8) pre-operatively to 41% (1.5 to 99.8) after multiple revision THRs (p = 0.03). There was a similar pattern after primary THR, but with considerably less muscle damage (p = 0.001), indicating progressive muscle damage. Despite an increased incidence of a positive Trendelenburg sign following revision surgery (p = 0.03) there was no relationship between the cumulative fatty degeneration in the gluteus medius and a positive Trendelenburg sign (p = 0.26). The changes associated with other surgical approaches to the hip warrant investigation. Cite this article: Bone Joint J 2014;96-B:1618–22

Introduction. Most of patients with unilateral hip disease shows muscle volume atrophy of pelvis and thigh in the affected side because of pain and disuse, resulting in reduced muscle weakness and limping. However, it is unclear how the muscle atrophy correlated with muscle strength in the patient with hip disorders. A previous study have demonstrated that the volume of the gluteus medius correlated with the muscle strength by volumetric measurement using 3 dimensional computed tomography (3D-CT) data, however, muscles influence each other during motions and there is no reports focusing on the relationship between some major muscles of pelvis and thigh including gluteus maximus, gluteus medius, iliopsoas and quadriceps and muscle strength in several hip and knee motions. Therefore, the purpose of the present study is to evaluate the relationship between muscle volumetric atrophy of major muscles of pelvis and thigh and muscle strength in flexion, extension and abduction of hip joints and extension of knee joint before surgery in patients with unilateral hip disease. Material and Methods. The subjects were 38 patients with unilateral hip osteoarthritis, who underwent hip joint surgery. They all underwent preoperative computed tomography (CT) for preoperative planning. There were 6 males and 32 females with average age 59.5 years old. Before surgery, isometric muscle strength in hip flexion, hip extension, hip abduction and knee extension were measured using a hand held dynamometer (µTas F-1, ANIMA Japan). Major muscles including gluteus maximus, gluteus medius, iliopsoas and quadriceps were automatically extracted from the preoperative CT using convolutional neural networks (CNN) and were corrected manually by the experienced surgeon. The muscle volumetric atrophy ratio was defined as the ratio of muscle volume of the affected side to that of the unaffected side. The muscle weakness ratio was defined as the ratio of muscle strength of the affected side to that of the unaffected side. The correlation coefficient between the muscle atrophy ratio and the muscle weakness ratio of each muscle were calculated. Results. The average muscle atrophy ratio was 84.5% (63.5%–108.2%) in gluteus maximus, 86.6% (65.5%–112.1%) in gluteus medius, 81.0% (22.1%–130.8%) in psoas major, and 91.0% (63.8%–127.0%) in quadriceps. The average muscle strength ratio was 71.5% (0%–137.5%) in hip flexion, 88.1% (18.8%–169.6%) in hip abduction, 78.6% (21.9%–130.1%) in hip extension and 84.3% (13.1%–122.8%) in knee extension. The correlation coefficient between the muscle atrophy and the ratio of each muscle strength between the affected and unaffected side were shown in Table 1. Conclusion. In conclusion, the muscle atrophy of gluteus medius muscle, psoas major muscle and quadriceps muscle significantly correlated with the muscle weakness in hip flexion. The muscle atrophy of psoas major muscle and quadriceps muscle also significantly correlated with the muscle weakness in knee extension. There were no significant correlation between the muscle atrophy and the muscle weakness in hip extension and abduction

Complete or nearly complete disruption of the attachment of the gluteus is seen in 10–20% of cases at the time of THA. Special attention is needed to identify the lesion at the time of surgery because the avulsion often is visible only after a thickened hypertrophic trochanteric bursa is removed. From 1/1/09 to 12/31/13, 525 primary hip replacements were performed by a single surgeon. After all total hip components were implanted, the greater trochanteric bursa was removed, and the gluteus medius and minimus attachments to the greater trochanter were visualised and palpated. Ninety-five hips (95 patients) were found to have damage to the muscle attachments to bone. Fifty-four hips had mild damage consisting of splits in the tendon, but no frank avulsion of abductor tendon from their bone attachments. None of these cases had severe atrophy of the abductor muscles, but all had partial fatty infiltration. All hips with this mild lesion had repair of the tendons with #5 Ticron sutures to repair the tendon bundles together, and drill holes through bone to anchor the repair to the greater trochanter. Forty-one hips had severe damage with complete or nearly complete avulsion of the gluteus medius and minimus muscles from their attachments to the greater trochanter. Thirty-five of these hips had partial fatty infiltration of the abductor muscles, but all responded to electrical stimulation. The surface of the greater trochanter was denuded of soft tissue with a rongeur, the muscles were repaired with five-seven #5 Ticron mattress sutures passed through drill holes in the greater trochanter, and a gluteus maximus flap was transferred to the posterior third of the greater trochanter and sutured under the vastus lateralis. Six hips had complete detachment of the gluteus medius and minimus muscles, severe atrophy of the muscles, and poor response of the muscles to electrical stimulation. The gluteus medius and minimus muscles were sutured to the greater trochanter, and gluteus maximus flap was transferred as in the group with functioning gluteus medius and minimus muscles. Postoperatively, patients were instructed to protect the hip for 8 weeks, then abductor exercises were started. The normal hips all had negative Trendelenburg tests at 2 and 5 years postoperative with mild lateral hip pain reported by 11 patients at 2 years, and 12 patients at 5 years. In the group of 54 with mild abductor tendon damage that were treated with simple repair, positive Trendelenburg test was found in 5 hips at 2 years and in 8 hips at 5 years. Lateral hip pain was reported in 7 hips at 2 years, and in 22 at 5 years. In the group of 35 hips with severe avulsion but good muscle tissue, who underwent repair with gluteus maximus flap transfer, all had good abduction against gravity and negative Trendelenburg tests at 2 and 5 years postoperative, and none had lateral hip pain. Of the 6 hips with complete avulsion and poor muscle who underwent abductor muscle repair and gluteus maximus flap transfer, all had weak abduction against gravity, mildly positive Trendelenburg sign, and mild lateral hip pain at 2 and 5 years postoperative. Abductor avulsion is uncommon but not rare, and is detected during THA only by direct examination of the tendon and removal of the trochanteric bursa. Simple repair of mild abductor tendon damage did not prevent progressive abductor weakness in some hips; and the increase in number of patients with lateral hip pain from 2 to 5 years suggests progressive deterioration. Augmentation of the repair with a gluteus maximus flap appears to provide a stable reconstruction of the abductor muscles, and seemed to restore abductor function in the hips with functioning muscles

Introduction. Gluteus medius is disrupted during lateral approach total hip arthroplasty (THA) which may impact its function and ability to control the pelvis. The objective was to compare gluteus medius activation and joint mechanics associated with a Trendelenburg sign (pelvic drop, trunk lean) during gait and hip abductor strength between patients that underwent lateral or posterior THA approaches one year post-surgery and healthy adults. Methods. Participants that underwent primary THA for hip osteoarthritis using lateral (n=21) or posterior (n=21) approaches, and healthy adults (n=21) were recruited for this cross-sectional study. Participants completed five walking trials. Surface electromyography captured gluteus medius activation. A 3-dimensional optical motion capture system measured frontal plane pelvic obliquity and lateral trunk lean angles. Participants performed maximum voluntary isometric contractions (MVIC) on a dynamometer to measure hip abductor torque. Characteristics from gait waveforms were identified using principal component analysis, and participant waveforms were scored against these characteristics to produce principal component scores. One-way analysis of variance and effect sizes (d) compared gait principal component scores and isometric hip abductor torque between groups. Results. Lateral THA group had statistically significant higher gluteus medius PC-scores indicating higher overall amplitudes during gait (p<0.01, d=0.97) and prolonged midstance activation (p=0.01, d=0.95) compared to the healthy group (Figure). There were no statistically significant (p>0.05) differences in pelvis or trunk angles. Isometric hip abductor torque was significantly (p=0.03, d=0.74) lower in the lateral THA than healthy group. There were no statistically significant differences between THA groups (d=0.27–0.50). Conclusions. Although the lateral THA group had lower abductor torque, there were no Trendelenburg signs during gait. Elevated gluteus medius activation in this group was a compensation for the weakness, and the muscle produced sufficient force to control the pelvis. Also, 1 year post-THA there were no statistically significant gait differences between lateral and posterior approaches. For any tables or figures, please contact the authors directly

Few surgical techniques to reconstruct the abductor mechanism of the hip have been reported, with outcomes reported only from case reports and small case series from the centres that described the techniques. As in many of our revision THA patients the gluteus maximus was affected by previous repeat posterior approaches, we opted to reconstruct the abductor mechanism using a vastus lateralis to gluteus medius transfer. We report the results of such reconstructions in seven patients, mean age 66 (range, 53–77), five females, presenting with severe abductor deficiency (MRC grade 1–2). Five patients had previous revision THA, two with a proximal femoral replacement, one patient had a primary THA after a failed malunited trochanteric fracture, and one patient had a native hip with idiopathic fatty infiltration of glutei of >90%. All patients had instrumented gait analysis, and surface electromyography (EMG) of the glutei, TFL, and vastus muscles simultaneously before surgery and at each post-op follow-up. Postoperatively, patients were allowed to weight bear as tolerated and were requested to wear an abduction brace for the first six weeks after surgery to protect the transfer. All patients improved after surgery and reached an abductor power of 3 or more. All patients walked without support six months after surgery and were satisfied with the result. Abductor function continued to improve beyond one year of follow-up, and some patients reached an abductor power of 5. EMG demonstrated that the transferred vastus lateralis started firing synchronously with gluteus medius after three months post-surgery, suggesting adaptation to its new function. No knee extension weakness was recorded. One patient complained of lateral thigh numbness and was dissatisfied with the cosmetic look of her thigh after surgery. Our preliminary results are encouraging and comparable with those achieved by the originators of the technique

The direct lateral (or anterolateral) approaches to the hip for revision THA involve detachment of the anterior aspect of the gluteus medius from the trochanter along with a contiguous sleeve of the vastus lateralis. Anterior retraction of this flap of gluteus medius and vastus lateralis and simultaneous posterior retraction of the femur creates an interval for division of gluteus minimus and deeper capsular tissues and exposure of the joint. To enhance reattachment of this flap of the anterior portion of the gluteus medius and vastus lateralis back to the trochanter, an oblique wafer of bone can be elevated along with the muscle off of the anterolateral portion of the trochanter. This bony wafer prevents suture pull out when large nonabsorbable sutures are used around or through the fragment and passed into the bone of the trochanteric bed for reattachment during closure. To prevent excessive splitting proximally into the gluteus medius muscle (and resulting damage to the superior gluteal nerve), it is often helpful to extend the muscle split further distally down into the vastus lateralis. This combined with careful elevation of the gluteal muscles off of the ilium (instead of splitting them) helps provide excellent and safe exposure of the entire rim of the acetabulum and access to the supracetabular region for bone grafting, acetabular augment placement and even fixation of the flanges of a cage. A simple method for posterior column plating via the anterolateral approach involves contouring of the distal end of the plate around the base of the ischium at the inferior edge of the socket. When an extended osteotomy of the femur is needed to correct deformity, remove a well-fixed implant or cement, the “extensile” variation of this same surgical approach involves a Wagner style (lateral to medial) osteotomy of the greater trochanter and proximal femur. The anterior portion of the femur after it is osteotomised is elevated as a separate segment while maintaining the soft tissue attachments to the bone as much as possible to aid osteotomy healing. After implant or cement removal, this approach gives excellent direct access to the distal femur for placement of a long stem revision femoral component without bone-implant conflict proximally because of the bow of the femur. The anterolateral approach (and extensile variants detailed above) can be used routinely and safely in the full range of revision THA procedures, or it can be employed selectively, if desired, in cases at increased risk for dislocation

The direct anterior approach in total hip replacement anatomically offers the chance to minimise soft-tissue trauma because an intermuscular and internervous plane is explored. This motivated us to abandon our previously used transgluteal approach and to adopt the direct anterior approach for total hip replacement. Using MRI, we performed a retrospective comparative study of the direct anterior approach with the transgluteal approach. There were 25 patients in each group. At one year post-operatively all the patients underwent MRI of their replaced hips. A radiologist graded the changes in the soft-tissue signals in the abductor muscles. The groups were similar in terms of age, gender, body mass index, complexity of the reconstruction and absence of symptoms. Detachment of the abductor insertion, partial tears and tendonitis of gluteus medius and minimus, the presence of peri-trochanteric bursal fluid and fatty atrophy of gluteus medius and minimus were significantly less pronounced and less frequent when the direct anterior approach was used. There was no significant difference in the findings regarding tensor fascia lata between the two approaches. We conclude that use of the direct anterior approach results in a better soft-tissue response as assessed by MRI after total hip replacement. However, the impact on outcome needs to be evaluated further

Introduction: It was hypothesized that ipsilateral upper extremity loading will decrease hip abductor activity by decreasing the adductor moment and thus relieving the symptoms of patients with gluteus medius tendinitis. The aim of the study was to test the hypothesis with a electrophysiological and clinical study. Materials and Methods: Seven voluntary men with no hip complaint were included in the electrophysiological phase of the study. The motor unit activities of the gluteus medius were measured for each subject during the consecutive loading of the ipsilateral, contralateral and both upper extremities, with 2, 3, 5 and 7 kilograms. Seventeen patients (age range 34–67) with acute symptoms of gluteus medius tendinitis were included in the clinical phase of the study. Dynamic VAS scores were recorded for each patient during gait with consecutive loading of the ipsilateral, contralateral and both upper extremities, for each 2, 3, 5 and 7 kilograms. Wilcoxon and Mann-Whitney U tests were used in statistical analysis. The p values below 0.05 were considered significant. Results: In the electrophysiologic study the ipsilateral upper extremity loading with 7 kg in 4 patients, and with 5 and 7 kilograms in 2 patients resulted in a motor unit activities with moderate interference, while motor unit activities with full interference were recorded during all other loadings. The motor unit activity interference scores recorded during the ipsilateral upper extremity loading with 5 kilograms of above, were significantly less then all other loading combinations (p < 0.05). In the clinical study, the ipsilateral upper extremity loading with 3 kilograms and above resulted in significantly less VAS scores then the other loading combinations (p< 0.05). Conclusion: Ipsilateral upper extremity loading decrease the motor unit activity of the ipsilateral gluteus medius muscle and relieves the symptoms of the patients with gluteus medius tendinitis. Ipsilateral upper extremity loading can lead up to new strategies in the rehabilitation of gluteus medius tendinitis

Abstract. Background. Progressive muscle ischaemia results in reduced aerobic respiration and increased anaerobic respiration, as cells attempt to survive in a hypoxic environment. Acute compartment syndrome (ACS) is a progressive form of muscle ischaemia that is a surgical emergency resulting in the production of Lactic acid by cells through anaerobic respiration. Our previous research has shown that it is possible to measure H+ ions concentration (pH) as a measure of progressive muscle ischaemia (in vivo) and hypoxia (in vitro). Our aim was to correlate intramuscular pH readings and cell viability techniques with the intramuscular concentration of key metabolic biomarkers [adenosine triphosphate (ATP), Phosphocreatine (PCr), lactate and pyruvate], to assess overall cell health in a hypoxic tissue model. Methods. Nine euthanised Wistar rats were used in a non-circulatory model. A pH catheter was used to measure real-time pH levels from one of the exposed gluteus medius muscles, while muscle biopsies were taken from the contralateral gluteus medius at the start of the experiment and subsequently at every 0.1 of a pH unit decline. The metabolic biomarkers were extracted from the snap frozen muscle biopsies and analyzed with standard fluorimetric method. Another set of biopsies were stained with Hoechst 33342, Ethidium homodimer-1 and Calcein am and imaged with a Zeiss LSM880 confocal microscope. Results. Our study shows that the direct pH electrode readings decrease with time and took an average of 69 minutes to drop to a pH of 6.0. The concentrations of ATP, pyruvate and PCr declined over time, and the concentration of lactate increased over time. At pH 6.0, both ATP and PCr concentrations had decreased by 20% and pyruvate has decreased by 50%, whereas lactate had increased 6-fold. The majority of cells were still viable at a pH of 6.0, suggesting that skeletal muscle cells are remarkably robust to hypoxic insult, although this was a hypoxic model where reperfusion was not possible. Conclusions. Our research suggests that histologically, skeletal muscle cells are remarkably robust to hypoxic insult despite the reduction in the total adenine nucleotide pool, but this may not reflect the full extent of cell injury and quite possibly irreversible injury. The timely restoration of blood flow in theory should halt the hypoxic insult, but late reperfusion results in cellular dysfunction and cell death due to localised free radical formation. Further research investigating the effects of reperfusion in vivo are warranted, as this may identify an optimal time for using pharmacological agents to limit reperfusion injury, around the time of fasciotomy to treat acute compartment syndrome. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims. The gluteus minimus (GMin) and gluteus medius (GMed) have unique structural and functional segments that may be affected to varying degrees, by end-stage osteoarthritis (OA) and normal ageing. We used data from patients with end-stage OA and matched healthy controls to 1) quantify the atrophy of the GMin and GMed in the two groups and 2) describe the distinct patterns of the fatty infiltration in the different segments of the GMin and GMed in the two groups. Methods. A total of 39 patients with end-stage OA and 12 age- and sex frequency-matched healthy controls were prospectively enrolled in the study. Fatty infiltration within the different segments of the GMin and the GMed was assessed on MRI according to the semiquantitative classification system of Goutallier and normalized cross-sectional areas were measured. Results. The GMin was smaller in the OA-group (p < 0.001) compared to the control group, but there was no group difference in the size of the GMed (p = 0.101). Higher levels of fatty infiltration were identified in the anterior segment of the GMin (p = 0.006) and the anterior (p = 0.006) and middle (p = 0.047) segments of the GMed in the OA group. All subjects in the control group had fatty infiltration of the anterior segment of the GMin, but all except one had no fatty infiltration in the entire GMed. Conclusion. End-stage OA was associated with significant atrophy of the GMin and higher levels of fatty infiltration, particularly in the anterior segments of the GMin and GMed. Minor fatty infiltration of the anterior segment of GMin appears to be a normal part of ageing. Our study has demonstrated different patterns of atrophy and fatty infiltration between patients with end-stage OA and healthy matched peers. Cite this article: Bone Jt Open 2021;2(1):40–47

Introduction. Complete or nearly complete disruption of the gluteus attachment is seen in 10–20% of cases at the time of total hip arthroplasty (THA). Special attention is needed to identify the lesion at the time of surgery because the avulsion often is visible only after a thickened hypertrophic trochanteric bursa is removed. The purpose of this study was to evaluate a technique designed to restore abductor function by transferring the gluteus maximus to compensate for the deficient medius and minimus muscles. Methods. From Jan 1 2009 to Dec 31 2013, 525 primary THAs were performed by the author. After the components were implanted, the greater trochanteric bursa was removed, and the gluteus medius and minimus attachments to the greater trochanter were visualized and palpated. Ninety-five hips (95 patients) were found to have damaged muscle attachments to bone. Fifty-four hips had mild damage consisting of splits in the tendon, but no frank avulsion of abductor tendon from the bone attachment. None had severe atrophy of the abductor muscles, but all had partial fatty infiltration. All hips with this mild lesion had repair of the tendons with #5 Ticron sutures to repair the tendon bundles together, anchored to the greater trochanter. Forty-one hips had severe damage with complete or nearly complete avulsion of the gluteus medius and minimus muscles from their attachments to the greater trochanter. Thirty-five of these hips had partial fatty infiltration of the abductor muscles, but all responded to electrical stimulation. The surface of the greater trochanter was denuded of soft tissue with a rongeur, the muscles were repaired with five-seven #5 Ticron mattress sutures passed through drill holes in the greater trochanter, and a gluteus maximus flap was transferred to the posterior third of the greater trochanter and sutured under the vastus lateralis. Six hips had complete detachment of the gluteus medius and minimus muscles, severe atrophy of the muscles, and poor response of the muscles to electrical stimulation. The gluteus medius and minimus muscles were sutured to the greater trochanter, and the gluteus maximus flap was transferred. Postoperatively, patients were instructed to protect the hip for 8 weeks, then abductor exercises were started. Results. The normal hips all had negative Trendelenburg tests at 2 and 5 years postoperative with mild lateral hip pain reported by 11 patients at 2 years, and 12 patients at 5 years. In the 54 with mild abductor tendon damage treated with simple repair, positive Trendelenburg test was found in 5 hips at 2 years and in 8 hips at 5 years. Lateral hip pain was reported in 7 hips at 2 years, and in 22 at 5 years. In the 35 hips with severe avulsion but good muscle tissue, who had repair with gluteus maximus flap transfer, all had good abduction against gravity and negative Trendelenburg tests at 2 and 5 years postoperative, and none had lateral hip pain. Of the 6 hips with complete avulsion and poor muscle who underwent abductor muscle repair and gluteus maximus flap transfer, all had weak abduction against gravity, mildly positive Trendelenburg sign, and mild lateral hip pain at 2 and 5 years postoperative. Conclusions. Abductor avulsion is uncommon but not rare, and is detected during THA only by direct examination of the tendon and removal of the trochanteric bursa. Simple repair of mild abductor tendon damage did not prevent progressive abductor weakness in some hips; and the increase in number of patients with lateral hip pain from 2 to 5 years suggests progressive deterioration. Augmentation of the repair with a gluteus maximus flap appears to provide stable reconstruction of the abductor muscles, and seemed to restore function in the hips with functioning muscles

After THR, trochanteric soft tissue abnormalities may be associated with residual trochanteric pain and limping. However, normal MR appearance of the trochanteric region after THR is not known. The aim was to evaluate MR imagings in asymptomatic and symptomatic patients after THR through a transgluteal approach. Triplanar MR images of 25 asymptomatic (14 men, mean age 60.4 years, 11 women, mean age 60.2) and 49 symptomatic patients (19 men, mean age 62.7 years, 20 women, mean age 64.3) at least 1 year after THR were analyzed by two blinded radiologists. In 14 symptomatic patients MR imaging was correlated to surgical findings. Tendon defects were uncommon in asymptomatic and significantly more frequent in symptomatic patients (gluteus minimus 8% vs. 56%, p< 0.001; lateral gluteus medius 16% vs 62%, p< 0.001; posterior gluteus medius 0% vs18%, p< 0.025). Signal changes within tendons were very frequent in both groups except for the posterior gluteus medius tendon which demonstrated this finding more frequently in symptomatic patients (20% vs 59%, p=0.002). Changes in tendon diameter were very frequent in both groups but significantly (p=0.001–009) more frequent in symptomatic patients. Fatty atrophy was evident in the anterior two thirds of the gluteus minimus muscle in both asymptomatic and symptomatic patients. In the posterior superior third of the gluteus minimus muscle differences of fatty degeneration were significant. Fatty atrophy of the gluteus medius muscle was only present in symptomatic patients. Bursal fluid collections were more frequent in asymptomatic (32% vs 62%, p=0.021). MR diagnosis was confirmed in all 14 patients undergoing revision surgery. Although more frequent in symptomatic patients many MR findings are frequently found in asymptomatic patients. However, defects of the abductor tendons and fatty atrophy of the gluteus medius and the posterior part of the gluteus minimus muscle are rare in asymptomatic patients

No animal model currently exists for hip abductor tendon tears. We aimed to 1. Develop a large animal model of delayed abductor tendon repair and 2. To compare the results of acute and delayed tendon repair using this model. Fourteen adult Romney ewes underwent detachment of gluteus medius tendon using diathermy. The detached tendons were protected using silicone tubing. Relook was performed at six and 16 weeks following detachment, histological analysis of the muscle and tendon were performed. We then attempted repair of the tendon in six animals in the six weeks group and compared the results to four acute repairs (tendon detachment and repair performed at the same time). At 12 weeks, all animals were culled and the tendon–bone block taken for histological and mechanical analysis. Histology grading using the modified Movin score confirmed similar tendon degenerative changes at both six and 16 weeks following detachment. Biomechanical testing demonstrated inferior mechanical properties in both the 6 and 16 weeks groups compared to healthy controls. At 12 weeks post repair, the acute repair group had a lower Movin's score (6.9 vs 9.4, p=0.064), and better muscle coverage (79.4% of normal vs 59.8%). On mechanical testing, the acute group had a significantly improved Young's Modulus compared to the delayed repair model (57.5MPa vs 39.4MPa, p=0.032). A six week delay between detachment and repair is sufficient to produce significant degenerative changes in the gluteus medius tendon. There are significant histological and mechanical differences in the acute and delayed repair groups at 12 weeks post op, suggesting that a delayed repair model should be used to study the clinical problem

Introduction. The results of repair and reconstruction of lesions found in the abductor muscles and tendons during posterior approach to primary total hip arthroplasty (THA) were reported in 2018. During the course of this series it became apparent that the extent of damage in the abductor tendons and muscles usually was obscured by the hypertrophic greater trochanteric bursa, especially the deep layer adherent to the greater trochanter and abductor muscles. The purpose of this study was to evaluate the surgeon's ability to see these lesions during standard posterior approach, and also to describe the dissection necessary to fully expose them. Patients and Methods. A total of 525 patients (525 hips) underwent primary THA through posterior approach between 2009 and 2013. Fifty-four patients had mild chronic damage to the tendon. Forty-one patients had severe damage with major avulsion of the gluteus medius and minimus muscles. Results. None of the hips with normal abductor muscle structure had a dense trochanteric bursa to obscure the abductor attachment to bone, but in 35 hips (85.3%) with significant abductor tendon avulsion, the lesions in the tendons were hidden from view until the greater trochanteric bursa was dissected. Splitting the deep layer of the trochanteric bursa in line with the fibers of the abductor muscles was necessary to reveal avulsion of the tendons from the edge of the greater trochanter. Only six hips (14.6%) had abductor tendon avulsion from the greater trochanter that could be seen without removing the trochanteric bursa tissue. Conclusion. The posterior approach offered excellent exposure of the abductor mechanism during primary THA, but the avulsion defects in the gluteus medius and minimus muscles remained obscured until the outer layer of the greater trochanteric bursa was completely removed and the deep fibrous layer was dissected adequately to expose the tendon attachment to bone. For any tables or figures, please contact the authors directly

Aims. We wished to quantify the extent of soft-tissue damage sustained during minimally invasive total hip arthroplasty through the direct anterior (DA) and direct superior (DS) approaches. Materials and Methods. In eight cadavers, the DA approach was performed on one side, and the DS approach on the other, a single brand of uncemented hip prosthesis was implanted by two surgeons, considered expert in their surgical approaches. Subsequent reflection of the gluteus maximus allowed the extent of muscle and tendon damage to be measured and the percentage damage to each anatomical structure to be calculated. Results. The DA approach caused substantially greater damage to the gluteus minimus muscle and tendon when compared with the DS approach (t-test, p = 0.049 and 0.003, respectively). The tensor fascia lata and rectus femoris muscles were damaged only in the DA approach. There was no difference in the amount of damage to the gluteus medius muscle and tendon, piriformis tendon, obturator internus tendon, obturator externus tendon or quadratus femoris muscle between approaches. The posterior soft-tissue releases of the DA approach damaged the gluteus minimus muscle and tendon, piriformis tendon and obturator internus tendon. Conclusion. The DS approach caused less soft-tissue damage than the DA approach. However the clinical relevance is unknown. Further clinical outcome studies, radiographic evaluation of component position, gait analyses and serum biomarker levels are necessary to evaluate and corroborate the safety and efficacy of the DS approach. Cite this article: Bone Joint J 2016;98-B1036–42

Introduction: The anterior and anterolateral approach to the hip traditionally are well described exposures in primary hip arthroplasty with fewer dislocations than the posterior approach. A very debilitating complication associated with the anterolateral approach however is the persistent limp and positive Trendelenburg sign. We discuss our results with respect to abductor function and morphological integrity seen on MRI when using an approach in which we preserve the majority of gluteus medius. Methods: We carried out a prospective study of thirty-nine consecutive total hip replacements performed through a gluteus medius sparing anterolateral approach. The same hip surgeon performed all these between April and October 2004. Gait analysis and Trendelenburg tests were evaluated during clinical follow-up at six weeks and three months. Coronal STIR and T1 weighted MRI sequences of the abductors were performed between four and six weeks and the findings were agreed by the consensus of two radiologists. Results: At three-month follow-up all thirty-nine patients tested Trendelenburg negative. Post-operative radiographs showed satisfactory femoral and acetabular component position. MRI findings showed the gluteus medius tendon to be intact with no shortening on T1. Artefacts were found to be less marked in the higher field strength magnet but more apparent in the STIR weighted sequences. Discussion: We have tried to incorporate the advantages of reduced dislocation rate of the anterolateral approach, whilst avoiding violation of the abductors. The clinical result and radiographic findings we have presented suggest that the described exposure is an effective and safe method of approaching the hip, with minimal disruption of the abductor mechanism. In addition to maintaining the reduced dislocation rate associated with the standard anterolateral approach. Intact abductor function allows for rapid rehabilitation

Tannast has recently shown that safe hip dislocation (SHD) for femoroacetabular impingement treatment does not result in atrophy and degeneration of periarticular hip muscles. In more complex procedures, such as relative neck lengthening for Perthes disease (PD) or modified Dunn procedure for slipped capital epiphysis (SCFE), minimus gluteus femoral insertion is detached to achieve enough mobility of osteotomized trochanter and to fix the latter more distally. Aim of this study was to evaluate MRI appearance of minimus and medius gluteus after relative neck lengthening. Patients treated with SHD and relative neck lengthening eventually associated to epiphyseal realignment for PD or SCFE treatment underwent magnetic resonance imaging (MRI) to study gluteus minimus (MI) and medius (ME) muscles. In the axial T1-weighted sequences, cross sectional area (CSA) and signal intensity were evaluated at acetabular roof level. Statistical comparison was made with the opposite healthy side. Fifteen patients underwent an MRI at an average of 59 months (SD=27.3) after surgery. Average ratio between gluteus minimus CSA (treated/healthy side) was 0.90 (SD=0.2): this reduction in volume was statistically significant (p=0.04) as well as the signal intensity (p=0.04). CSA and signal intensity of gluteus medius did not differ between two sides (respectively p=0.78 and p=0.30). In conclusion, gluteus medius appearance was not influenced by distal fixation of the trochanter. The minimus gluteus was reduced in volume as much as 10% in respect to healty side; increased signal intensity in MRI T1-weighted (fatty infiltration) was found in the minimus gluteus

Abstract. Extended Trochanteric Osteotomy (ETO) improves surgical exposure and aids femoral stem and bone cement removal in Revision Total Hip Replacement (RTHR) surgery. The aim of this study was to identify healing rates and complications of ETO in RTHR. Methods. From 2012 to 2019 we identified patients who underwent ETO for RTHR. Data collected demographics, BMI, diabetes, anticoagulants, indication for ETO, surgical approach, length of ETO and complications. Descriptive analysis of patient demographics, multiple linear regression analysis was performed to assess ETO complications. Results. There were 63 patients with an average age of 69 years. Indications for ETO were aseptic loosening (30), infection (15), periprosthetic fracture (9), recurrent dislocation (5), broken implant (4). There were 44 cemented and 19 uncemented femoral stem that underwent ETO. Average time from index surgery was 12 years (less than a year to 38 years). All procedures were through posterolateral approach and all ETO were stabilised with cables. Average length of ETO was 12.5cm. BMI varied from 18 to 37. There were 5 diabetics and 16 on anticoagulants. All but one ETO went on to unite. Other complications included infection, dislocations, lateral thigh pain and significant limp. Discussion. Fixation of ETO can be with either wires or cables or plate with cables/screws. Advantages of cables are no irritation over greater trochanter, no disruption of gluteus medius/vastus lateralis continuity, reproducible tension in cables and use of torque limiter minimises loss of tension in cables

Introduction. Hip abductor tendon tears have been referred to as “rotator cuff tears of the hip,” and are a recognized etiology for persistent, often progressive, lateral hip pain, weakness, and limp. Multiple repair techniques and salvage procedures for abductor tendon tears have been reported in the literature; however, re-tear remains a frequent complication following surgical repair. This study compares the short-term outcomes of open abductor tendon repairs with decortication and suture fixation (DSF) compared to a modified technique repair into a bone trough (BT), to determine best surgical results for large abductor tendon avulsions. Additionally, surgical treatment of small tears versus large tears was examined. Methods. The outcomes of 37 consecutive hip abductor tendon repairs treated between January 2009 and December 2017 were retrospectively reviewed. Large tears were defined as detachment of 33–100% of the gluteus medius insertion. There were 15 DSF and 10 BT cases. Postoperative pain, ability to perform single leg stance, hip abduction, and Trendelenburg lurch, were examined. Small tears (12 cases) were defined as having no gluteus medius avulsion from the trochanteric insertion and were comprised of longitudinal tears (repaired side-by-side) and isolated gluteus minimus tears (repaired by tenodesis to the overlying gluteus medius). Standard statistical analyses were utilized. Type I error for all analyses was set at α=0.05. Results. When comparing large tear repair outcomes, repairs into a BT had superior outcomes to repairs with DSF: 0 (BT) versus 6 (DSF, 40%) failure rate (p<0.05), and greater reductions in pain at one-year post surgery (Δ VAS: BT, −5.70±0.97 | DSF: −2.73±0.69; p<0.01), ability to perform a single leg stance and hip abduction (90% and 100% vs 47% and 73%) (p<0.05). Clinical strength ratings were higher for repairs into a BT, but this did not reach statistical significance. When comparing large to small tear repair outcomes, small tears were found to have lower VAS pain scores and higher clinical strength ratings during both the pre-op and 1-year post-op time points (p<0.05). A higher percentage of those with small tears were able to perform a single leg stance and hip abduction (100%) compared to those with large tears (64% and 78% respectively) (p<0.05). A significantly higher frequency of residual lurch was also observed for those with large tears; 56% compared to small tears at 0%. Conclusions. Utilizing a BT repair significantly improved surgical results for large abductor tendon avulsions. Level of evidence: Therapeutic level IV case series

The musculoskeletal (MSK) profiles of water polo players and other overhead athletes has been shown to relate to injury and throwing performance (TP). There have been no robust studies conducted on the MSK profiles and the variables affecting TP amongst female, adolescent, elite water polo players. A prospective quantitative cohort design was conducted amongst eighty-three female adolescent, elite water polo players (range 14–19 years). All participants filled out the Kerlan-Jobe Orthopaedic Clinic questionnaire, followed by a battery of screening tests aimed to identify possible MSK factors affecting TP. Pain provocation tests, range of motion (ROM), upward scapula rotation (USR), strength and pectoralis minor length measurements were all included. Participants also performed throwing speed (TS) and throwing accuracy (TA) tests. All the data collected were grouped together and analysed using SPSS 28.0. The condition for statistical significance was set as p <0.05. Multi-collinearity was tested for among variables to find out inter-variable correlations. Finally, a multiple regression analysis was performed. The mean KJOC score was 82.55 ± 14.96. 26.5% tested positive for at least one of the impingement tests. The MSK profile revealed decreased internal rotation ROM, increased external rotation ROM, a downwardly rotated scapula, weak external rotators, weak serratus anterior strength, strong lower trapezius and gluteus medius strength and a shorter pectoralis minor length all on the dominant side. Age, pectoralis minor length, upper trapezius and serratus anterior strength as well as upward scapula rotation were all positively correlated with TS, while sitting height, upper trapezius and serratus anterior strength and glenohumeral internal rotation ROM were positively correlated with TA. Multiple MSK parameters were found to be related to TS and TA in elite, adolescent water polo players

Avulsion of the abductor muscles of the hip may cause severe limp and pain. Limited literature is available on treatment approaches for this problem, and each has shortcomings. This study describes a muscle transfer technique to treat complete irreparable avulsion of the hip abductor muscles and tendons. Ten adult cadaver specimens were dissected to determine nerve and blood supply point of entry in the gluteus maximus and tensor fascia lata (TFL) and evaluate the feasibility and safety of transferring these muscles to substitute for the gluteus medius and minimus. In this technique, the anterior portion of the gluteus maximus and the entire TFL are mobilised and transferred to the greater trochanter such that the muscle fiber direction of the transferred muscles closely matches that of the gluteus medius and minimus. Five patients (five hips) were treated for primary irreparable disruption of the hip abductor muscles using this technique between January 2008 and April 2011. All patients had severe or moderate pain, severe abductor limp, and positive Trendelenburg sign. Patients were evaluated for pain and function at a mean of 28 months (range, 18–60 months) after surgery. All patients could actively abduct 3 months post-operatively. At 1 year post-operatively, three patients had no hip pain, two had mild pain that did not limit their activity, three had no limp, and one had mild limp. One patient fell, fractured his greater trochanter, and has persistent limp and abduction weakness. The anterior portion of the gluteus maximus and the TFL can be transferred to the greater trochanter to substitute for abductor deficiency. In this small series, the surgical procedure was reproducible and effective; further studies with more patients and longer follow-up are needed to confirm this

Purpose: Replacing the entire femur for primary bone tumour is exceptional. Prostheses used in this series were custom-made by Link using the Endo Klinik (Hambourg) model. These prostheses have adjustable ante-version and a hinge type knee with rotation. Patients and Results: Case n° 1. A 15-year-old boy, grade 2A osteosarcoma in the diaphyseal zone of the lower femur. Rosen chemotherapy. En bloc resection. Total femur prosthesis sleeved onto the trochanteric mass left in place. Excellent response:100%. Excellent functional result: mountain climbing! Current status: recurrence-free, metastasis-free at 16 years follow-up. Case n° 2. Adult osteosarcoma. 68-year-old woman with pulmonary metastasis at diagnosis. Indication due to fracture to mid third of femur. Excellent immediate result. Nine-month survival in very satisfactory condition. Case n° 3. 72-year-old woman treated one year earlier for T1N0M0 breast cancer. Metastatic image in the trochanter. Treatment by curettage and THA. Histology reported chondrosarcoma. Scintigraphy showed uptake in gluteus medius and the lower part of the femur. En bloc resection of entire femur and gluteus medius. Total femur replacement with prosthesis sleeved onto an allograft. Complete resection. Current status: recurrence-free, metastasis-free at five years. No limitation on walking distance. Walks with cane due to moderate limp. Case n° 4. Adult osteosarcoma (32 years). Low-grade tumour (1B) occupying the entire femur. Rizzoli Institute chemotherapy protocol. Resection and total femur replacement with prosthesis sleeved onto an allograf. Complete resection. Poor response. Excellent functional result, persistence of minimal limp. Active tumour with pulmonary metastasis at one year and death at 1.5 yers. Case n° 5. Grade 2B osseous leiomyosarcoma in the diaphyseal zone of the lower femur in a 37-year-old woman. Neoadjuvant chemotherapy followed by total femur resection. Excellent responder:100%. Excellent functional outcome at short follow-up (1 year). Discussion: Total femur replacement with a prostheses sleeved on an allograft allows reinsertion of the gluteus medius and the psoas. This method is reliable and avoids major instability. Complications in this small number of patients were rare and were not serious. The functional results have been excellent and appear to depend primarily on the importance of muscle resection required to achieve tumour resection

The direct anterior approach (DAA) is a popular minimally invasive approach for total hip arthroplasty (THA). It usually involves ligation of the lateral femoral circumflex artery's ascending branch (a-LFCA), which contributes to the perfusion of the tensor fasciae latae (TFL) muscle. Periarticular muscle status and clinical outcome were assessed after DAA-THA after a-LFCA preservation versus ligation. We evaluated surgical records of 161 patients undergoing DAA-THA with tentative preservation of the a-LFCA by the senior author between May and November 2021. Among 92 eligible patients, 33 (35 hips) featured successful preservation, of which 20 (22 hips, 13 female) participated in the study. From 59 patients with ligated a-LFCA, 26 (27 hips, 15 female) were enrolled, constituting the control group. MRI and clinical examinations were performed at 17–26 months to analyze volume and fatty infiltration of the TFL, gluteus medius and gluteus minimus muscles relative to the contralateral non-THA hip (15 preserved, 18 ligated). Clinical and radiographic data was retrospectively extracted from patient files. Patient-reported outcomes (PROMs) were added from the THA registry. There was a relative difference in TFL muscle volume of -6.27 cm. 3. (−9.89%, p=0.018) after a-LFCA preservation versus -8.6 cm. 3. (=11.62%, p=0.002) after ligation, without group differences (p>0.340). a-LFCA preservation showed lower relative TFL fatty infiltration (p=0.10). Gluteal muscle status was similar between sides and groups. Coxa valga morphology was more frequent in a-LFCA preservation (83%) than ligation (17%). Clinical outcomes showed high patient satisfaction in both groups, without difference in PROMs, but less anterolateral soft-tissue swelling after a-LFCA preservation (p<0.001). Despite excellent clinical results in both groups, preservation of the a-LFCA was associated with less TFL fatty infiltration and soft tissue swelling. Provided there is no compromise of intraoperative access we recommend a-LFCA preservation for DAA-THA

Tenotomy of the iliopsoas tendon has been described as an effective procedure to treat refractive groin pain induced by iliopsoas tendinitis. However, the procedure forces the rectus femoris to act as the primary hip flexor and little is known about the long-term effects of this procedure on the peri-articular muscle envelope (PAME). Studies suggest that iliopsoas tenotomy results in atrophy of the iliopsoas and decreased hip flexion strength with poorer outcomes, increasing the susceptibility for secondary tendinopathy. The aim of this study is to describe changes in the PAME following psoas release. All patients who presented for clinical examination at our hospital between 2016 and 2021 were retrospectively reviewed. Patients who presented after psoas tenotomy with groin pain and who were unable to actively lift the leg against gravity, were included. Pelvic MRI was taken. Qualitative muscle evaluation was done with the Quartile classification system. Quantitative muscle evaluation was done by establishing the cross-sectional area (CSA). Two independent observers evaluated the ipsi- and contralateral PAME twice. The muscles were evaluated on the level: iliacus, psoas, gluteus minimus-medius-maximus, rectus femoris, tensor fasciae lata, piriformis, obturator externus and internus. For the qualitative evaluation, the intra- and inter-observer reliability was calculated by using kappastatistics. A Bland-Altman analysis was used to evaluate the intra- and inter-observer reliability for the quantitative evaluation. The Wilcoxon test was used to evaluate the changes between the ipsi- and contra-lateral side. 17 patients were included in the study. Following psoas tenotomy, CSA reduced in the ipsilateral gluteus maximus, if compared with the contralateral side. Fatty degeneration occurred in the tensor fascia latae. Both CSA reduction and fatty degeneration was seen for psoas, iliacus, gluteus minimus, piriformis, obturator externus and internus. No CSA reduction and fatty degeneration was seen for gluteus medius and rectus femoris. Conclusions/Discussion. Following psoas tenotomy, the PAME of the hip shows atrophy and fatty degeneration. These changes can lead to detrimental functional problems and may be associated with debilitating rectus femoris tendinopathy. In patients with psoas tendinopathy, some caution is advised when considering an iliopsoas tenotomy

Falls in adults are a major problem and can lead to injuries and death. In order to better understand falls and successful recoveries, identifying kinematics, kinetics, and muscle forces during recovery from loss of balance is crucial. To obtain reactive gait patterns, participants must be subjected to unexpected perturbations such as trips and slips. Previous researchers have reported kinetics recovery data following stumbling; however, the muscle force recovery patterns remain unknown. To better target exercises to reduce the risk of falls, we must first understand which muscles, their magnitude, and their coordination patterns, play a role in a successful recovery from a trip and a slip. Additionally, knowing the successful patterns of lower limb function can help with the diagnosis of faulty movements. A total of 20 healthy adults in their twenties with similar athletic backgrounds were perturbed on a split-belt treadmill using Computer-Assisted Rehabilitation Environment (Motkforce Link) at a preset speed of 1.1m/s. Two kinds of perturbations were administered: slip and trip. Slips were simulated by accelerating one belt, whereas trips were simulated by decelerating one belt. Both perturbations had similar intensity and only differed in the direction. Computational modeling was used to obtain lower-limb function during the compensatory step. SPM paired t-test was used to compare differences in recovery strategies between slip and trip through magnitude and patterns of joints. There were no significant differences in joint angles post tripping vs post-slipping. Results of net joint moments showed that compensating for the loss of balance due to tripping required a higher ankle plantarflexion moment than slipping (at 22-52%; 1.2± 0.3vs0.4±0.2, p<0.001). Additionally, larger gluteus maximus (at 40-50%;8.7±3.8vs2.7±1.1N/kg, p=0.001), gluteus medius (at23~33%; 22.6±5.7vs6.8±3.6N/kg, p<0.001) were generated than post-slipping, respectively. These findings suggested that greater GMAX and GMED forces are required post-trip recovery than slip. Future analysis of trip recovery showed the importance of ankle joint in recovering from forward and backward fall. These results can be used as references in remote diagnosis of joint and muscle weakness and assessment of the risk of falls with the use of accelerometers

Revision hip approaches can be divided into posterior, anterior, transgluteal, and transtrochanteric. The approach chosen is dictated by what needs to be exposed and the approaches with which the surgeon is comfortable. The posterior approach remains posterior to the gluteus medius and protects the hip abductors. The disadvantage of a posterior approach is post-operative dislocation. The direct anterior approach is currently enjoying popularity as a primary technique. Surgeons experienced in the primary technique are applying it to revision surgery. The anterior approaches also protect the hip abductors. The disadvantage is poor access to the posterior acetabular column and mobilization of the femur to gain access to the femoral diaphysis. Transgluteal approaches split the gluteus medius typically keeping the anterior portion of the medius intact with the vastus lateralis. Proximal exposure is limited by the superior gluteal nerve, which is 4 cm above the tip of the trochanter. The disadvantage of the transgluteal approach is difficult access to the posterior acetabular column and occasional abductor weakness. The advantage of both the anterior and transgluteal approaches is a lower dislocation rate. All three approaches are acceptable for revisions that only require acetabular rim and proximal femoral exposure. More extensive exposure requires modifications to these approaches or the use of a transtrochanteric approach. Transtrochanteric approaches are defined by the length of the osteotomy (conventional or extended) and if the vastus lateralis remains attached to the trochanteric fragment (slide). Distally extended osteotomies improve access to the femur. Osteotomies without a distal attachment to the lateralis can be retracted proximally thus improving exposure of the ilium

Introduction: Complex fracture of the acetabulum are difficult to treat. If an osteosynthesis is performed difficult surgery resulted in blood loss, long operating time, high risk of sepsis and failure. Even if the fracture is well operated and ideally stabilised there is a major risk of secondary osteoarthrosis. This can be related to bone necrosis , cartilage surface damage , bone loss. There are also intraoperative risks of neural damage: sciatic nerve as well as gluteus medius nerve. On the other hand , modern surgical technique including an alumina against alumina bearing could allow very long term survival without any activity limitation and this even in very young patients. Secondary procedure after a failed osteosynthesis provides statistically worse functional results than primary total hip. The surgery is more difficult because of hardware retrieval, nerve dissection, bone reconstruction and remaining muscular dysfunction. Materials and Methods: To address these issues we reviewed our results of total hip for acetabular fractures. 80 patients received a total hip for acetabular fracture. From 1980 to 1998: 58 acetabular fractures in 57 patients sustained a total hip: 39 males and 18 females. Mean age: 50 years (from 21 to 80). 35 had had a conservative treatment, 22 had had an osteosynthesis. Delay between fracture and total hip: operated: 10 years, non-operated: 6 years. All prosthesis had an alumina against alumina couple. The stem was always made of titanium alloy, it was smooth, collared and cemented. The socket was plain alumina cemented 8, cement less : 3, metal back alumlina insert: 29, screw in cup with alumina liner: 10, plain polyethylene cemented: 8. Results: Follow-up: from 6 months to 20 years (mean 5,5years). Last Postel Merle d’Aubigne rating: 16,1(8–18) 9 revisions : 1 bipolar aseptic loosening, 8 socket loosening : 2 septic , 6 aseptic. (2 screws in , 6 cemented). There were 22 neural disorder; 19 sciatic palsies; 13 post trauma; 4 post osteosynthesis; 2 post THR; 3 gluteus medius palsy. 7 sepsis: 4 post osteosynthesis, 3 post THR (including 2 post osteosynthesis). Discussion: The results presented were inferior to a regular total hip if an osteosynthesis have been performed previously. Reasons for these inferior results were limp due to previous palsy of gluteus medius nerve, sciatic sequellae, complications of previous sepsis and so on. In contrast cases who had at first orthopaedic treatment followed some weeks later by a total hip experienced very good results. It is difficult to conclude from this limited series. But we are actually on the way to modify our perspectives. Many weak results could have been avoided by doing fine primary surgery. We could expect better functional results with less complications regarding sepsis, nerve damage, muscle preservation if we perform a primary total hip in conjunctions with acetabular reconstruction. Osteosynthesis is still recommended for simple acetabular fracture with large displacement involvement of the posterior wall or one column not comminuted

We describe a modified lateral approach to the hip which exploits the functional continuity of gluteus medius and vastus lateralis and their dense crescentic attachment to the greater trochanter. The gluteus medius is not incised or split, but is detached and mobilised with gluteus minimus as one unit. This facilitates reattachment of the glutei and helps to preserve abductor function

Revision hip approaches can be divided into posterior, anterior, transgluteal, and transtrochanteric. The approach chosen is dictated by what needs to be exposed and the approaches with which the surgeon is comfortable. The posterior approach remains posterior to the gluteus medius and protects the hip abductors. The disadvantage of a posterior approach is post-operative dislocation. The direct anterior approach is currently enjoying popularity as a primary technique. Surgeons experienced in the primary technique are applying it to revision surgery. The anterior approaches also protect the hip abductors. The disadvantage is poor access to the posterior acetabular column and mobilisation of the femur to gain access to the femoral diaphysis. Transgluteal approaches split the gluteus medius typically keeping the anterior portion of the medius intact with the vastus lateralis. Proximal exposure is limited by the superior gluteal nerve, which is 4cm above the tip of the trochanter. The disadvantage of the transgluteal approach is difficult access to the posterior acetabular column and occasional abductor weakness. The advantage of both the anterior and transgluteal approaches is a lower dislocation rate. All three approaches are acceptable for revisions that only require acetabular rim and proximal femoral exposure. More extensive exposure requires modifications to these approaches or the use of a transtrochanteric approach. Transtrochanteric approaches are defined by the length of the osteotomy (conventional or extended) and if the vastus lateralis remains attached to the trochanteric fragment (slide). Distally extended osteotomies improve access to the femur. Osteotomies without a distal attachment to the lateralis can be retracted proximally thus improving exposure of the ileum

Muscle atrophy has been demonstrated in patients suffering from osteoarthritis of the hip, but little is known about muscular recovery after total hip replacement (THR). A total of 20 patients with unilateral osteoarthritis of the hip were assessed before, six months and two years after THR. The cross-sectional area and radiological density of the muscles of the hip, thigh, calf and back were measured using CT. We hypothesised that the muscles would not recover fully after operation. After two years comparison of the limb with the THR with the healthy limb showed that there was such a reduction in the cross-sectional area in iliopsoas (7.0%; p = 0.006) and the hip adductors (8.4%, p = 0.003) and in the radiological density in gluteus maximus (10.1 Hounsfield units; p < 0.001), gluteus medius/minimus (5.6 Hounsfield units; p = 0.011), iliopsoas (3.9 Hounsfield units; p < 0.001) and the adductors (2.4 Hounsfield units; p = 0.022). Thus, there was persistent muscle atrophy in muscles acting about the hip two years after THR. We suggest that an earlier operation or a more intensive rehabilitation may reverse these changes

Mini-incision total hip arthroplasty seeks to eliminate some complications of traditional extensile exposure and also facilitates more rapid post-operative rehabilitation. Posterior approach has been associated with increased risk of posterior dislocation. Thus, a modified mini-incision lateral approach of Hardinge was described not only to overcome this problem by preserving the posterior capsule, but also allows adequate access for orientation of the implant. The author has modified the Hardinge approach by a V-shaped incision where the apex is centered over the tip of the greater trochanter with the one limb extending proximally along the fibers of the gluteus medius muscle and the distal limb extending across the proximal part of vastus lateralis. This innovative surgical approach is described in this article. Conclusion. Larger incisions and surgical approaches have been associated with larger blood loss, greater need for perioperative transfusion, use of more postoperative analgesics, a longer hospital stay, and a slower recovery. In this modified approach, the gluteus medius is left intact. The postoperative strength of the abductors of the operated side was the same as that on the non-operated side and functionally, the direct lateral approach was a safe alternative to other approaches in decreasing the trendelenburg gait and incidence of heterotrophic ossification

The authors modified the original minimally invasive (MI) two-incision total hip arthroplasty (THA) technique and used large-diameter (32mm, 36mm) ceramic-on-ceramic articulation. One hundred and seventy patients that underwent unilateral MI two-incision THA retrospectively reviewed, and surgical morbidities, functional recoveries, radiological implantation properties, and complications were assessed. The mean follow-up was 30.2 months (range, 24-42 months) and mean patient age was 50.4 years (range, 22-83 years). In the lateral position, an anterolateral approach between the gluteus medius and tensor fascia lata and a posterior approach between the piriformis and gluteus medius was used. Mean operation time was 71.2 minutes (range, 48-91 minutes). Mean Harris hip score improved from 41.8 (range, 10-59) to 96.1 (range, 73-100) at last follow-up, and mean WOMAC score from 66.2 (range, 49-96) to 26.9 (range, 24-39). The mean lateral opening angle of the acetabular component was 38.2° (range, 32.1°-47.7°) and the mean stem position was valgus 1.9° (range, varus 2.3° to valgus 4.8°). One patient suffered an intraoperative femur fracture and another underwent revision surgery due to stem subsidence. No patient experienced dislocation. Our data suggest the this modified technique is safe and reproducible in terms of achieving proper implant positioning and early functional recovery. In particular, the complication rates encountered, especially the dislocation rate, were low

Purpose. Hip arthroplasty is a good treatment option for displaced femoral neck fracture in elderly patients. However, neuromuscular disease such as cerebral infarction or hemorrhage can be a concerning problem for THA since dislocation after operation can frequently occur. The purpose of this prospective study was to evaluate the functional results of modified minimally invasive (MI) two-incision total hip arthroplasty (THA) with the use of large-diameter (>38mm) metal-on-metal articulation in patients with muscle weakness. Patients and Methods. 19 consecutive patients (19 hips) with displaced femoral neck fracture with muscle weakness were enrolled. There were 11 patients with cerebral infarction, 4 patients with cerebral hemorrhage and 4 patients with Parkinson's disease. In the lateral position, an anterolateral approach between the gluteus medius and tensor fascia lata and a posterior approach between the piriformis and gluteus medius were used. Surgical morbidity, functional recovery, radiological implantation properties, range of motion (ROM) and complications were assessed. Results. The mean operation time was 73.5 minutes and the average perioperative blood loss was 725.9cc. The mean head diameter used was 44 mm (38–50). The mean lateral opening angle of the acetabular component was 38.4°, the mean anteversion of the acetabular component was 16.4°, and the mean stem position was 0.3° valgus. The average postoperative ambulation time was 2.4 days. The mean Harris hip score was 81.0 at final follow-up, and the mean WOMAC score was 42.9. At final follow-up, there was no case of dislocation. There was no hypersensitivity, no osteolysis, and no revision. Conclusions. Our study suggests that the functional results of modified MI two-incision THA with the use of large-diameter metal on metal articulation in patients with muscle weakness can produce satisfactory early functional recovery and can reduce the dislocation rate

The aim of the study is to investigate the biomechanical effects on the pelvis of the anterolateral and posterolateral approaches at the time of hip arthroplasty. In particular the study investigates the change in stress distribution, and the change in muscle recruitment pattern following surgery. The study uses an advanced finite element model of the pelvis, in which the role of muscles and ligaments in determining the stress distribution in the pelvis is included. The model is altered for the posterolateral approach by excision of the external rotators. Different levels of gluteal damage for the anterolateral approach are modelled by excising in turn the anterior third, half, and two-thirds of the gluteus medius and minimus. Although attempt is generally made to repair gluteal damage at the time of surgery, it is clear the muscle volume will be compromised immediately after surgery. In support of previous clinical studies indicating an increased risk of limp, and pelvic tilt following the anterolateral approach, significant differences were found in the muscle recruitment pattern following the anterolateral, compared to the posterolateral approach. During single leg stance and walking force transfer to the iliacus and pectineus was observed. Required levels of muscle force, to maintain coronal balance, following the anterolateral approach were found to be close to maximum sustainable levels. In addition significant alteration to the pelvic stress distribution was found following the anterolateral approach. The effects of increasing gluteal damage for the anterolateral approach were progressive, and became more pronounced when more than fifty percent of the gluteus medius and minimus were damaged. Increases in stresses around the acetabulum were observed for the posterolateral, compared to the anterolateral approach. Thus, based on a biomechanical evaluation, the anterolateral approach presents increased risk of limp, and pelvic tilt, in comparison to the posterolateral approach

Introduction: We present here the clinical features and management strategies of patients with gluteus medius and minimus enthesopathy. Methodology: We studied seven patients with lateral hip pain and tenderness on palpation, worse over the tip of the greater trochanter. All of them had a positive Trendelenburg’s sign, and a transient relief of pain on injecting local anaesthetic in the abductor mechanism. All of these patients were tertiary referrals from the rheumatologists, who had at least once injected them with corticosteroids. Results: Four of these seven patients underwent exploration. An insertional tendinopathy of the abductors was noted in all the patients, and was debrided. Two of the patients had, in addition, a tear in the gluteus medius tendon, which was repaired. One patient had an injection of local anaesthetic and Aprotinin in the abductor mechanism with resolution of symptoms. Discussion: Gluteus medius and minimus enthesopathy is a distinct clinical entity. Although the condition has been described in the radiological literature, we were unable to find any reference to the orthopaedic management of this condition. We observed only a small number of patients, and we are thus unable to provide definite answers. Patients presenting with the above clinical features warrant consideration of the diagnosis of abductor enthesopathy. Ultrasound scan or MRI scan helps in confirming the diagnosis. At present, our management protocol involves injecting a local anaesthetic / Aprotinin in the abductor mechanism. However, we are cautious in injecting more than once, as, at operation, we have observed necrosis of the abductor mechanism at its insertion in two patients, similar to that described for Achilles tendon. If this fails, we undetake surgical exploration. The exact surgical procedure is difficult to predict and may involve debridement and repair of the pathological tendon

1. Telemetering electromyography has been used to investigate the pattern of activity of certain muscles of the lower limb and back while the subjects walked up and down stairs. 2. During walking up and down stairs each limb has a supporting and swinging phase in each complete step. 3. Walking up stairs revealed the following facts. Firstly, raising the body on to the stair above is brought about by the contraction of the soleus, quadriceps femoris, hamstrings and gluteus maximus; the gluteus medius at the same time prevents the body falling on to the unsupported side. Secondly, the tibialis anterior dorsiflexes the foot during the swinging phase and helps the limb to clear the stair on which the supporting limb is placed. Thirdly, the hamstrings flex the leg at the knee in the early part of the swinging phase and control the terminal part of extension at the knee at the end of this phase. Fourthly, both erectores spinae contract twice in each step and control the forward bending of the body at the vertebral column. 4. Walking down stairs revealed the following. Firstly, the body is lowered on to the stair below by the controlled lengthening of the soleus and quadriceps femoris; the gluteus medius at the same time prevents the body from falling on to the unsupported side. Secondly, the tibialis anterior inverts the foot at the beginning of the supporting phase as the toe is placed on the stair below and dorsiflexes the foot in the middle of the swinging phase. Thirdly, the hamstrings control the extension of the leg at the knee during the middle of the swinging phase. Fourthly, both erectores spinae contract twice in each step and prevent forward bending of the trunk at the vertebral column

Introduction: Due to the diversity of the prosthetic implants for hip arthroplasty, a better matching between the implant and the intra and extra-medullary characteristic of the patient anatomy is now possible. This adaptation however requires a perfect understanding of the tridimensional characteristics of the patient hip anatomy. Little data are available in the literature. We aimed to analyze the muscular and bony anatomy of the hip at the time of arthroplasty. Material and Methods: data acquisition was performed according a standardized CT-scan in the same center for all patients within the standard workup before arthroplasty. Standardized measurements were obtained after automatic tridimensional bone reconstructions using dedicated software. 549 femurs in 469 patients including primitive coxarthrosis (COX), dysplasic development of the hip (DDH) and aseptic osteonecrosis (ONA) were analyzed. Mean age was 58 and 70% of the patients were women. Tridimensional reconstruction of the muscular anatomy of the hip was performed for 30 patients using manual contouring on dedicated software. Characteristics of the bony and muscular anatomy were then analyzed according to the etiology and correlations between bony and muscular anatomy were evaluated. Results: Concerning the bone analysis, mean offset was 23.2 ±1.5mm in the DDH group, 40.5±1.2 mm in the COX group and 29.6± 0.9mm in the ONA group(p< 0.001). Neck-shaft angle was 132±25º in the DDH group, 130±0.5º in the COX group and 134±1º in the ONA group (p< 0.001). Mean anteversion was 33±3.5º in the DDH group, 25±3.8º in the COX group and 16±3.2º in the ONA group (p< 0.001). Concerning the muscular analysis, gluteus medius and minimus volumes were correlated with the body mass index and with the gender, but not with patient age (p: NS). Location of the muscular insertion of the gluteus medius and minimus on the greater trochanter were correlated with the femoral anteversion. Discussion: The results of our study demonstrated that bony and muscular anatomical characteristics were correlated with the etiology of the degenerative joint disease, with the patient body mass index and gender. Surgeons should be aware of these characteristics to improve the patient anatomy reconstruction during the arthroplasty

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients who underwent a modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulations for osteonecrosis of the femoral head. Methods. One hundred and one patients (135 hips) who underwent unilateral minimally invasive two-incision total hip arthroplasties using large diameter ceramic-on-ceramic bearings for osteonecrosis of the femoral head with a minimum 12-months follow-up were included in this study. There were 22 women and 79 men who had a mean age of 46 years (range, 22 to 82 years). The mean follow-up was 25 months (range, 12 to 36 months). All surgeries were done by a single hip surgeon. The authors modified the original minimally invasive two-incision total hip arthroplasty technique and used large-diameter (32mm, 36mm) ceramic-on-ceramic articulations. In the lateral position, an anterolateral approach between the gluteus medius and tensor fascia lata muscles and a posterior approach between the piriformis and gluteus medius muscles was used. Functional results were measured by Harris hip (HHS) and WOMAC scores. Radiographic evaluation was assessed for positioning of the components and complications were assessed. Results. The mean Harris hip score improved from 43 points (range, 13 to 58 points) pre-operatively to 96 points (range, 73 to 100 points) post-operatively and the mean WOMAC score improved from 67 points (range, 50 to 98 points) to 28 points (range, 26 to 39 points). On radiological evaluation, the mean lateral opening angle of the acetabular component was 35.9 degrees (range, 27.1 degrees to 47.4 degrees) and the mean stem position was valgus 2.4 degrees (range, varus 2.7 degrees to valgus 5.3 degrees). One patient suffered an intra-operative femur fracture and another underwent revision surgery due to stem subsidence. There were no complications such as immediate post-operative deep infection, delayed infection, or recurrent dislocation. Conclusion. A modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulation for osteonecrosis of the femoral head is safe and reproducible in terms of achieving proper implant positioning and early functional recovery. In particular, the complication rates encountered, especially dislocation, were low

Introduction. It was the purpose to evaluate the biomechanical changes that occur after optimal and non-optimal component placement of a hip resurfacing (SRA) by using a subject specific musculoskeletal model based on CT-scan data. Materials and Methods. Nineteen hips from 11 cadavers were resurfaced with a BHR using a femoral navigation system. CT images were acquired before and after surgery. Grey-value segmentation in Mimics produced contours representing the bone geometry and identifying the outlines of the 3 parts of the gluteus medius. The anatomical changes induced by the procedure were characterised by the translation of the hip joint center (HJCR) with respect to the pelvic and femoral bone. The contact forces during normal gait with ‘optimal’ component placement were calculated for a cement mantle of 3 mm, a socket inclination of 45° and anteversion of 15°. The biomechanical effect of ‘non-optimal placement’ was simulated by varying the positioning of the components. Results. There was a significant (p<0.01) shortening of the muscle length with the ‘optimal’ component placement for all parts of the gluteus medius with the largest shortening of the posterior part by 6mm. This was caused by a significant shortening of the femoral offset by 2.3mm (p<0.01). Because of a significant (p<0.01) medialisation of the HJCR by 4 mm, there was no significant increase in contact force. The hip joint contact forces increased by 0.5% per mm HJCR displacement. Each millimeter of cranial and lateral displacement of the femoral HJCR increased the contact force by 0.5% and 1%, respectively. The contact stresses changed significantly by 0.8% and 0.2% per degree of socket inclination and anteversion. The contact force increased 1% per mm lateral displacement of the acetabular HJCR. Discussion. Optimal placement of the SRA components did not completely restore the biomechanics of the native hip joint. The contact forces were not increased due to the compensatory effect of the medialisation of the acetabular HJCR. This suggests that reaming to the acetabular floor should be conducted in SRA. Femoral component displacement in the cranial and lateral direction significantly increased the hip joint loading. Errors of socket placement in the coronal and sagital plane significantly increased the contact stresses. Accumulative errors of both component displacements could lead to increased contact stresses of 18% to 23% with socket inclinations of 50° and 55°. Surgeons should reconsider continuing the SRA procedure if a neck length loss and lateralisation of the HCJR by >5 mm is anticipated as this would increase the contact stresses by >12%

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients who underwent a modified minimally invasive two-incision total hip arthroplasty using large-diameter metal-on-metal articulations for osteonecrosis of the femoral head. Methods. From December 2007 to July 2008, 45 hips (33 patients) underwent total hip arthroplasty for the treatment of osteonecrosis of the femoral head. There was 1 woman (2 hips) and 32 men (43 hips) who had a mean age of 39 years (range, 22 to 64 years). The minimum follow-up was 12 months (range, 12 to 19 months). The authors modified the original minimally invasive two-incision total hip arthroplasty technique and used large-diameter metal-on-metal articulations. In the lateral position, an anterolateral approach was used between the gluteus medius and tensor fascia lata muscles and for the posterior approach the muscle plane was between the piriformis and gluteus medius muscles. The acetabular components, Durom¯ (Zimmer) in 20 hips and Magnum¯ (Biomet) was used in 25 hips. M/L taper¯ (Zimmer) femoral stems were used in all cases. The size of the femoral heads were 38 mm (1 hip), 40 mm (3 hips), 42 mm (13 hips), 44 mm (18 hips), 46 mm (5 hips), 48 mm (4 hips) and 50 mm (1 hip). Postures such as excessive flexion or adduction which cause dislocation were not restricted, post-operatively. Functional results were measured by Harris hip scores (HHS), WOMAC scores, and range of motion. Radiographic evaluation was assessed for positions of components and post-operative complications were noted. Results. Mean operation time was 72 minutes (range, 54 to 94 minutes). The mean Harris hip score improved from 50 points (range, 38 to 73 points) pre-operatively to 96 points (range, 84 to 100 points) post-operatively, and the mean WOMAC score improved from 68 points (range, 50 to 93 points) to 28 points (range, 26 to 34 points). The mean flexion improved from 85° pre-operatively to 122° post-operatively. The mean internal rotation improved from 2.5° pre-operatively to 25.3° post-operatively. The mean external rotation improved from 31.8° pre-operatively to 60.1° post-operatively. The mean abduction improved from 24.0° pre-operatively to 41.6° post-operatively. The mean adduction improved from 19.4 ° pre-operatively to 26.6° post-operatively. All patients were able to sit cross legged and squat. On radiological evaluation, the mean lateral opening angle of the acetabular component was 39.4° (range, 32.2°-48.5°) and the mean stem position was valgus 0.3° (range, varus 2.8° to valgus 2.0°). At last follow-up, all femoral and acetabular components were well-fixed without loosening or subsidence. There were no complications such as dislocation, immediate post-operative deep infection or delayed infection. Conclusion. Modified minimally invasive two-incision total hip arthroplasty using large-diameter metal-on-metal articulations for osteonecrosis of the femoral head results in satisfactory early clinical and radiologic results

Introduction and Objective. Heterotopic ossification is the formation of extraskeletal mineralized tissue commonly associated with either trauma or surgery. While several mouse models have been developed to better characterize the pathologic progression of HO, no model currently exists to study HO of the hip, the most common location of acquired HO in patients. Owing to the unique biological mechanisms underpinning the formation of HO in different tissues, we sought to develop a model to study the post-surgical HO of the hip. Materials and Methods. Wild-type mice C57BL/6J mice were used to study the procedure outcomes, while Pdgfra-CreERT2;mT/mG and Scx-GFP reporter animals were used for the lineage tracing experiments (total n=16 animals, male, 12 weeks old). An anterolateral approach to the hip was performed. Briefly, a 2 cm incision was made centered on the great trochanter and directed proximal to the iliac crest and distally over the lateral shaft of the femur. The joint was then reached following the intermuscular plane between the rectus femoris and gluteus medius muscles. After the joint was exposed, the articular cartilage was removed using a micropower drill with a 1.2 mm reamer. The medius gluteus and superficial fascia were then re-approximated with Vicryl 5-0 suture (Ethicon Inc, Somerville, NJ) and skin was then closed with Ethilon 5-0 suture (Ethicon Inc). Live high resolution XR imaging was performed every 2 wks to assess the skeletal tissues (Faxitron Bioptics, Tucson, AZ). The images were then scored using the Brooker classification. Ex-vivo microCT was conducted using a Skyscan 1275 scanner (Bruker-MicroCT, Kontich, Belgium). 3D reconstruction and analysis was performed using Dragonfly (ORS Inc., Montreal, Canada). For the histological analysis of specimens, Hematoxylin and Eosin (H&E), modified Goldner's Trichrome (GMT) stainings were performed. Reporter activity was assessed using fluorescent imaging. Results. Substantial periarticular heterotopic bone was seen in all cases. A periosteal reaction and an initial formation of calcified tissue within the soft tissue was apparent starting from 4 wks after surgery. By XR, progressive bone formation was observed within the periosteum and intermuscular planes during the subsequent 8 weeks. Stage 1 HO was observed in 12.5% of cases, stage 2 in 62.5% of cases, and stage 3 HO in 25% of cases. 3D microCT reconstructions of the treated hip joints demonstrated significant de novo heterotopic bone in several location which phenocopy human disease. Heterotopic bone was observed in an intracapsular location, periosteal location involving the iliac bone and proximal femur, and intermuscular locations. Histological analyses further confirmed these findings. To assess the cells which gave rise to HO in this model, an inducible PDGFRα and constitutive Scx-GFP reporter mice were used. A dramatic increase in mGFP reporter activity was noted PDGFRα within the HO injury site, including in areas of new cartilage and bone formation. Scx-associated reporter activity increased in the soft tissue and periosteal periacetabular areas of injured hips. Conclusions. HO has a diverse set of pathologies, of which joint associated HO after elective surgery is the most common. Here, we present the first mouse model of hip dislocation and acetabular reaming that mimics elements of human periarticular HO. The diverse locations of HO after acetabular reaming (intracapsular, intermuscular and periosteal) suggests the activation of different and specific HO program after surgery. Such a field effect would be consistent with local trauma and inflammation, which is a well-studied contributor to HO genesis. Not surprisingly, joint-associated HO significantly derives from PDGFRα-expressing cells, which has been shown to similarly give rise to intramuscular and intratendinous HO

A consecutive series of patients who underwent 113 total hip arthroplasty (THA) with minimally invasive surgery (MIS) (63 one-, 50 two-incision cases) were studied. One-incision THA was performed with a posterolateral approach. For the two-incision, the first incision for cup insertion was made over the anterolateral side of the hip and intermuscular dissection was performed between the gluteus medius and the tensor fascia lata. The second incision for stem insertion was made on the posterolateral side along the fiber of the gluteus maximus and intermuscular dissection was made between the gluteus medius and the piriformis. The average length of the skin incision and standard deviation (SD) in the one- and two-incision group was 7.5 ± 0.54 cm and 12.1 ± 0.93 cm (p < 0.001). Average surgical time for the two groups (and SD) was 52 ± 8.5 minutes and 70 ± 10.2 minutes (p = 0.042) in the one and two incision groups respectively. Fluoroscopy was used in the two-incision group for an average 6.0 ± 5.3 seconds. In the one-incision group, the average time was 1.3 ± 2.1 seconds. The patients in the one-incision group could walk on crutches at postoperative 3.7 days on average, and in the two-incision group at 1.6 days on average (p = 0.000). In the one-incision group, patients used crutches for 6 weeks on average, and in the two-incision group, patients used crutches for 3 weeks on average (p = 0.042). Complications that developed within 1 month of surgery in the one-incision group were: 1 case of DVT, 1 case of intra-operative fracture and 1 case of dislocation; for the two incision group there were: 1 case of DVT, 1 case of intra-operative fracture and 1 case of femoral nerve entrapment. Before surgery, the HHS for the one-incision group was 49.8 points, and for the two-incision group it was 49.6 points (p > 0.05). At the time of the follow up review conducted postoperatively 1 year, the average HHS was not significantly different (p > 0.05). However, the average function score in HSS for the two-incision group was superior to that of the one-incision group (p = 0.045). Preoperative WOMAC scores were not different for the two groups (68.7 in one-incision group and 70.9 in two-incision group, respectively, p > 0.05). However, the average WOMAC score for the two-incision group was better, especially for the function score (p = 0.001). The other hip functions, common in oriental persons, were also better in the two-incision group compared to the one-incision group. On the radiographs, the location of the femoral prosthesis inserted in the medullary cavity was usually central in both groups; only 4 cases showed varus in the one-incision group and 2 cases in the two-incision group. The opening angle of the acetabular component was 38.1° in the one-incision group and 39.2° in the two-incision group (p > 0.05). The anteversion of the acetabular component was 21.0° in the one-incision group and 22.2° in two-incision group (p > 0.05). As compared with one-incision MIS-THA, two-incision MIS-THA, although it is a more difficult procedure, produces superior results, recovery was faster and patient satisfaction was higher due to early rehabilitation and reduced soft tissue damage without increasing the complication frequency

The Superior Hip Approach allows for safe reconstruction of the hip while maximizing preservation of the surrounding soft tissues. The procedure involves an incision in the hip joint capsule posterior to the gluteus medius and minimus and anterior to the short external rotators. The technique involves preparation of the femur in-situ through the superior femoral neck and then excision of the femoral head, which avoids the attendant soft tissue dissection or injury associated with dislocation of the native hip. After component implantation, the capsule is closed anatomically. Two separate studies have demonstrated that over a 90-day period, patients whose hips were replaced using this technique consumed the least amount of cost of any patients treated by hip arthroplasty in the Commonwealth of Massachusetts. One study assessed all hips replaced in patients insured by Medicare over a four-year period. In this study, patients treated by the Superior Hip Approach were less costly by an average of more than $7,000 over 90 days. A second study assessed all hips replaced in patients insured by a large private insurer. This study showed again that patients treated by the Superior Hip Approach were the lowest cost patients. Notable, the cost on average was $23,500 less per procedure compared to the most well-known medical care organization in the state or roughly half the cost. Lower cost was due to both lower inpatient cost and reduced utilization of post-acute care resources. Since reduced resource utilization is a direct measure of accelerated recovery, these economic data combine with clinical outcomes and anatomical studies that document that the Superior Hip Approach is a reliable technique for achieving optimal results following THA