Aims

Osteopetrosis (OP) is a rare hereditary disease that causes reduced bone resorption and increased bone density as a result of osteoclastic function defect. Our aim is to review the difficulties, mid-term follow-up results, and literature encountered during the treatment of OP.

Introduction. Total hip arthroplaty (THA) using direct anterior minimal invasive (AMI) surgery is an attractive option to achieve a quicker habilitation. However, high complication rates were reported and very often related to technical difficulties at the time of surgery. We hypothesized that 3D preoperative planning may allow to anticipate these difficulties and to decrease the complications rates when using an AMI approach. Material and methods. A prospective observational study included 191 consecutive patients who underwent a primary cementless THA using an AMI. A 3D CT-scan based pre-operative planning was performed in order to anticipate the potential difficulties that may be encountered especially regarding the hip anatomy reconstruction and the implants stability. The components size and position were planned in order to restore the leg length, the offsets, and the anteversions. Postoperatively, a CT scan was performed in order to compare the final anatomy to the planning. Results. The real implants were the same than the ones planned in 94% for the cup, 96% for the stem and 100% for the neck. The hip anatomy was restored with a high accuracy: 0.1±3mm for the hip rotation centre, −1.6±3 mm for the leg length and 0.1±2.5mm for the femoral offset. All the surgical difficulties were anticipated. No false route and no dislocation occurred. A motorized reaming procedure of the femur was required in 6 patients because a very dense bone associated to a narrow femoral diaphysis. A varus neck was used in 60 % of cases mainly in order to compensate a decrease in the acetabular offset generated by the reaming procedure imposed by the acetabular dysplasia. A retroverted neck was used in 8% of patients because of a torsional abnormality and allowed to increase the stability (Figure 1). A severe femoral dysplasia was treated with a custom stem in 7% of cases in order to avoid a rotational osteotomy of the femur a trochanteromy (Figure 2). Discussion. No complication happened at the time of surgery and no dislocation occurred afterwards. False routes were avoided probably also thanks to the shape of the anatomic stem which presents an anterior sagittal curvature. This shape allowed an easier rasping procedure despite the limited exposure of the femur. Conclusion. 3D planning anticipates the potential surgical difficulties at the time of THA, and allow to increase the safety and the accuracy of the surgical procedure

Introduction. Implantation of total hip replacement (THR) remains a concern in patients with developmental dysplasia of the hip (DDH) because of bone deformities and previous surgeries. In this frequently young population, anatomical reconstruction of the hip rotation centre is particularly challenging in severe, low and high dislocation, DDH. The basic principles of the technique and the implant selection may affect the long-term results. The aim of the study was to compare surgical difficulties and outcome in patients who underwent THR due to arthritis secondary to moderate or severe DDH. Material and Methods. We assessed 131 hips in patients with moderate DDH (group 1) and 56 with severe DDH (Group 2) who underwent an alumina-on-alumina THR between 1999 and 2012. The mean follow-up was 11.3 years (range, 5 to 18). Mean age was 51.4 years in group 1 and 42.2 in group 2. There were previous surgery in 5 hips in group 1 and in 20 in group 2 (p<0.001). A dysplastic acetabular shape type C according to Dorr and a radiological cylindrical femur were both more frequent in group 2 (in both cases p<0.001). We always tried to place the acetabular component in the true acetabulum. Smaller cups (p<0.001), screw use for primary fixation (p<0.001) and bone autograft used as segmental reinforcement in cases of roof deficiency (p<0.001) were more frequent in group 2. Radiological analysis of the cup included acetabular abduction, version and Wiberg angles, horizontal, vertical, and hip rotation centre distances, and acetabular head index. Abductor mechanism reconstruction according to the lever arm distance and height of the greater trochanter was also evaluated. Cup placement within or outside Lewinnek´s safe zone was recorded. Two-way ANOVA with repeated measures were used to analyse clinical and radiological changes. Results. There were 6 cups revised for aseptic loosening, three in each group. Survivorship analysis at 15 years: 97.3% (95% IC 94.4–100) for group 1 and 93.0% (95% IC 85.2–100) for group 2 (p=0.186). Despite a worse preoperative status in group 2, the outcome improved similarly in both groups. Postoperative radiological measurements were better in group 1 except for acetabular acetabular and version angles. The improvement from the pre- to the post-operative situation was greater in group 2 except for the height of the greater trochanter. Acetabular component placement within the Lewinnek´s safe zone was similar in both groups. All revised cups were outside this zone. No osteolysis or complications related to the use of ceramics were found. Conclusions. The alumina-on-alumina THR provided good results in both groups including pain relief and functional improvement. Placing the acetabular component in the true acetabulum inside the Lewinnek safe zone can ensure a good result in these challenging dysplastic hips

The December 2024 Knee Roundup³⁶⁰ looks at: Unicompartmental knee arthroplasty and total knee arthroplasty in the same patient?; Lateral unicompartmental knee arthroplasty: is it a good option?; The fate of the unresurfaced patellae in contemporary total knee arthroplasty: early- to mid-term results; Tibial baseplate migration is not associated with change in PROMs and clinical scores after total knee arthroplasty; Unexpected positive intraoperative cultures in aseptic revision knee arthroplasty: what effect does this have?; Kinematic or mechanical alignment in total knee arthroplasty surgery?; Revision total knee arthroplasty achieves minimal clinically important difference faster than primary total knee arthroplasty; Outcomes after successful DAIR for periprosthetic joint infection in total knee arthroplasty.

Aims

Our objective was describing an algorithm to identify and prevent vascular injury in patients with intrapelvic components.

Introduction. Acetabular osteotomy is considered to be an alternative treatment for acetabular dysplasia, particularly in adolescents and young adults because the long-term results of total hip arthroplasty (THA) in such patients remain controversial. To our knowledge, few reports have described the relationship between the types of osteotomies and surgical difficulty. We compared the operative and clinical results of THA following the 3 main types of acetabular osteotomies, including Chiari osteotomy, rotational periacetabular osteotomy (RAO), and shelf acetabuloplasty. Methods. Operative records of 13 hips following Chiari osteotomy (Chiari group), 22 hips following RAO (RAO group), and 16 hips following shelf acetabuloplasty (Shelf group) were retrospectively reviewed. Operative records of 2475 primary THAs without previous osteotomies during the same period were reviewed as a control. The direct anterior approach was used for all hips. Results. The mean operative time was 57.7 ± 11.7 min in the Chiari group, 68.7 ± 25.7 min in the RAO group, 57.4 ± 20.5 min in the shelf group, and 50.6 ± 18.5 min in the Control group. The operative time was significantly longer in the RAO group than in the Control group (p < 0.05). The mean operative blood loss was 406 ± 277 g in the Chiari group, 439 ± 400 g in the RAO group, 377 ± 163 g in the Shelf group, and 379 ± 270 g in the Control group. Allogeneic blood transfusion was performed in 1 patient (4%) in the RAO group and in 26 patients (1%) in the Control group. Bulk bone augmentation to the acetabular defect was performed in 2 hips (15%) in the Chiari group, 7 hips (32%) in the RAO group, and 87 hips (3.5%) in the Control group. The requirement for bulk bone augmentation to the acetabular defect was significantly higher in the Chiari and RAO groups than in the Control group (p < 0.05). Aseptic loosening occurred in 2 cups in the RAO group and postoperative dislocation occurred in 1 hip in the Chiari group. Conclusion. RAO made the conversion to THA complicated because of acetabular defects. Chiari osteotomy was less effective and shelf acetabuloplasty had no effect on surgical results of conversion THA

Introduction: The goal of the study was to determine the precision of a three-dimensional pre-operative planning tool using a specific software (HIP-PLAN. ®. ) and an anatomic cementless neck-modular stem. Method: 223 patients who underwent a primary total hip replacement had a CT Scan before and after surgery. A pre-operative three-dimensional planning based on the CT-scan was performed. A cementless cup and a neck-modular stem were used. A computational matching of the pre-operative and the post-operative CT-scans was performed in order to compare the values of the planned anteversions and the planned displacement of the hip rotation center to the post-operative values. Results: The implanted component was the same as the one planned in 89% for the cup and 94% for the stem. For the mean femoral anteversion, there was no significant difference between the planned value (26.1° +/−11.8) and the post-operative value (26.9° +/−14.1). There was a poor correlation between the planned values and the actual ones for the acetabular cup anteversion (coefficient 0.17). The hip rotation center was restored with a precision of 0.73 mm +/3.5 horizontally and 1.2 mm +/−2 laterally. Limb length was restored with a precision of 0.3 mm +/−3.3 and the femoral off-set with a precision of 0.8 mm +/−3.1. There was no significant modification of the femoral off-set (0.07 p=0.7) which was restored or slightly increased in 93% of cases. Almost all the surgical difficulties were predicted. Conclusion: HIP-PLAN. ®. software is a reliable three-dimensional pre-operative planning tool which allows acurate prediction of components and hip anatomy

Introduction:. The development of new prostheses due to large resections has offered important opportunities to orthopedic surgeons mainly in oncology. A medline research can easily underline how poor is the international experience about this cases in nonunion: 75 results for megaprosthesis just 7 works in nonunion. It is proposed the experience of our department, which deals specifically with the treatment of nonunion, in cases of repeated failures to treatment. One of the most significant problems in the treatment of relapsing nonunion is the consequent worsening of joint function. Critical bone defects, sepsis, joint fractures and unclear relapsing nonunions are the most common cases for a megaprosthesis treatment. In these cases, even if it obtains the healing of nonunion the functional result would be presumptively poor. This radiological or clinical situation drove us, in such cases, to drastic solutions following the principles of cancer cases. We implanted megaprosthesis with either techniques: 1 stage or 2 stages depending on the clinical findings. In nonunion the main decision making was the septic or aseptic status. Materials and Methods:. we treated 32 patients with megaprosthesis replacing the nearest joint to the nonunion segment or both the proximal e distal one as follows: proximal femur, distal femur, proximal tibia, and total femur. The mean follow-up of patients is 12 months (2 yrs max, min 3 months). Clinical and serial radiographic evaluations with standard methods (RX in 45 days, 3-6-12-24 months) was performed; as well as monitoring of blood parameters for 2 months. Results:. Despite the average follow-up is not high, we do not aspect main differences to oncologic survival of the device, so our expectations and main interest to our experience is faced to the functional status of these patients and clinical evaluation in septic cases. In all cases, however, we get encouraging clinical results with such prosthesis. Complications: no neurologic defect was observed. The main surgical difficulty was the chronic reducing of the range of motion of the extending mechanism of the knee, usually not involved in such a way in oncologic cases. In these cases we were forced to reinforce mainly the patellar tendon with tendon substitutes. Discussion:. mega-prosthesis in post-traumatic cases can be considered, in extreme cases, as an available solution to the orthopedic surgeon. In oncological surgery the opportunity to get back to a good function although not a “restitution ad integrum” is a success, if it is possible to eradicate the tumor. Unfortunately, the high mortality associated with this disease does not allow us to have long-term follow-up due to the big amount of cases lost at the follow up. This situation creates a lack of certainty about the survival of this type of prosthesis and the medium-and long-term complications that may occur. Nevertheless, the patients treated by us should be considered oncological patients, not because of the disease but for the limited therapeutic options available. Conclusions:. We have to consider not mega-prosthesis more like a pipe dream, but rather, as a viable opportunity

Background: The Delta Inverse Shoulder Arthroplasty, has gained considerable popularity in France and Europe for Rotator Cuff (RC) deficient patients. However complications related to surgical difficulties with insertion, mechanical loosening, and polyethylene (PE) wear are now being reported. The increasing numbers of complications are alarming. Methods: A computerised analysis of the kinematics associated with inverse shoulder replacements has been developed. Different glenoid dome sizes and humeral cup dimensions have been tested. This has highlighted the deficiencies associated with the design of the inverse shoulder prostheses currently available on the market. Modifications of the prosthesis geometry and the inclusion of a mobile bearing have also been subjected to computer analysis and have demonstrated improved kinematics and a reduction in the risk of bone/prosthesis contact. A medium term follow-up of 9 patients with a mobile bearing Inverse shoulder design has been carried out. Compression tests have been carried out on the PE bearing to identify the risk of plastic deformity of the PE. Results: The results of the computerised analysis and the clinical results from the first 9 patients will be reported. One patient suffered an operative complication with failure of reduction of the prosthesis which was rectified at an immediate re-operation. The early clinical results are similar to the good results obtained with the Delta prosthesis. However polyethylene bearing failure has occurred in one case, highlighting the importance of optimising the geometry of the inverse shoulder. Both Radio-Stereometric Analyses (RSA) and prospective randomised studies comparing this Inverse prosthesis with either a Cuff Tear Arthropathy (CTA) hemiarthroplasty designes (when Gleno-Humeral(GH) OA is present) or with cuff reconstruction using augmentation (when no GH OA is present) have been designed and will be discussed

Total hip arthroplasty (THA) in neglected congenital dislocation of the hip (CDH) constitutes a challenging procedure, with surgical difficulties and complications. The purpose of this study was to analyse the complications of THAs in CDH. Between June 1983 and September 2002, 418 THAs-were performed in 356 patients with CDH, with a mean follow-up 108 (7–237)months. The mean age at surgery was 53.3 (24–79) years with 325 females and31 males. 83 patients had CDH in high position. 307 arthroplasties were cementless, 39 cemented and 72 hybrids. 40 stems were custom made. The cup always was positioned at the true acetabulum. 24 shortening osteotomies of the femur, 8 corrective supracondylar and 6 trochanteric osteotomies were performed. Preoperatively the average Merle d’Aubigne-Postel hip score was 1.1 for pain, 4.8 for range of motion and 3.1 for walking ability. Postoperatively the average hip score was 5.2, 4.7 and 5.3 respectively. The average length discrepancy was 8 cm (3–12) preoperatively and 1.5 cm remained in 8 patients. Complications included 7 intraoperative fractures of the femur, 12 dislocations, 4 peroneal nerve palsies that recovered, 25heterotopic ossifications, 7 deep vein thromboses, 3 pulmonary embolisms, early mechanical loosening in 4 cemented and 10 cementless cups and 3infections. Complications were diminished dramatically last years due to improved surgical technique, new available implants and preoperative evaluation of the hip with CT and CAD-CAM-CAE study that allowed better surgical planning with trial stem implantation from a series of stem designs and custom made femoral components manufacturing

Aims

There is evidence that morbidly obese patients have more intra- and postoperative complications and poorer outcomes when undergoing total hip arthroplasty (THA) with the direct anterior approach (DAA). The aim of this study was to determine the efficacy of DAA for THA, and compare the complications and outcomes of morbidly obese patients with nonobese patients.

Total hip arthroplasty (THA) in neglected congenital dislocation of the hip (CDH) constitutes a challenging procedure, with surgical difficulties and complications. The purpose of this study was to analyse the complications of THAs in CDH. Between June 1983 and September 2002, 418 THAs were performed in 356 patients with CDH, with a mean follow-up 108 (7–237) months. The mean age at surgery was 53.3 (24–79) years with 325 females and 31 males. 83 patients had CDH in high position. 307 arthroplasties were cementless, 39 cemented and 72 hybrids. 40 stems were custom made. The cup always was positioned at the true acetabulum. 24 shortening osteotomies of the femur, 8 corrective supracondylar and 6 trochanteric osteotomies were performed. Preoperatively the average Merle d’Aubigne-Postel hip score was 1.1 for pain, 4.8 for range of motion and 3.1 for walking ability. Postoperatively the average hip score was 5.2, 4.7 and 5.3 respectively. The average length discrepancy was 8 cm (3–12) preoperatively and 1.5 cm remained in 8 patients. Complications included 7 intraoperative fractures of the femur, 12 dislocations, 4 peroneal nerve palsies that recovered, 25 heterotopic ossifications, 7 deep vein thromboses, 3 pulmonary embolisms, early mechanical loosening in 4 cemented and 10 cementless cups and 3 infections. Complications were diminished dramatically last years due to improved surgical technique, new available implants and preoperative evaluation of the hip with CT and CAD-CAM-CAE study that allowed better surgical planning with trial stem implantation from a series of stem designs and custom made femoral components manufacturing

Introduction: Total en bloc spondylectomy (TES) as the only radical treatment option for sarcoma and solitary metastases of the spine was shown to markedly minimize local recurrences, improve patient quality of life and substantially increase overall survival rates. Due to surgical difficulty of TES and complex biomechanical demands in defect reconstruction multisegmental tumor involvement of the spine has long been considered as a palliative situation, exceeding the limits of surgical feasibility. Thus, multilevel resections reports are very rare. For the first time, this study analyzes the onco-surgical results after multilevel thoracolumbar TES and reconstruction with a carbon composite vertebral body replacement system (CC-VBR) in a collective of patients. Methods: 18 patients (9f/9m; age 52±14y) treated with thoracolumbar multilevel TES (6x2, 9x3, 3x4 segments) for spinal sarcomas (n=9), solitary metastases (n=5) and aggressive primary tumors (n=3) were retrospectively investigated. According to the classification system of Tomita et al. all patients were surgically staged as type 6 (multisegmental/extracompartimental). Defect reconstruction (11 thoracic, 3 thoracolumbar and 4 lumbar) were performed with posterior stabilization and a CC-VBR. Patient charts and the current clinical follow-up results were analyzed for histopathological tumor type, pre- and postoperative data (symptoms, duration of surgery, blood loss, complications, intensive care, adjuvant therapies etc.) and course of disease. Latest radiographs and CT-scans were analyzed at follow up. Oncological status was evaluated using cumulative disease specific and metastases-free survival analysis. Results: With a mean follow up (100%) of 18 (4–44) months 17 patients (94%) were postoperatively ambulatory without any support. Postoperative neurological deficits were seen in one patient (6%). Wide resection margins were attained in 7, marginal in 11 patients. Depending on tumor biology/grading and/or resections margins an adjuvant therapy (radiation/chemotherapy) was performed in 12 (67%) patients. Local recurrence was found in one patient (6%). 13 (72%) patients showed no evidence of disease, 3 were alive with disease while 2 died of disease at 10 and 27 months postoperatively. Conclusion: In selected patients with multisegmental spinal tumor involvement oncological sufficient resections can be reached by multilevel TES. Although the surgical procedure is challenging and the patient’s stress is considerable our encouraging midterm results together with the low complication rate clearly favour and legitimate this technique. However, treatment success strongly depends on adjuvant therapies. Reconstruction with a CC-VBR showed low complication rates, promising biomechanical characteristics, increased volume for bone grafting and lower artefact rates in follow-up MR- and CT-imaging

Aims

The incidence of atypical femoral fractures (AFFs) continues to increase. However, there are currently few long-term studies on the complications of AFFs and factors affecting them. Therefore, we attempted to investigate the outcomes, complications, and risk factors for complication through mid-term follow-up of more than three years.

Introduction: Tumors of the axilla impose a surgical difficulty because they are usually large at presentation and in close proximity to the major neurovascular bundle of the upper extremity. Attempted tumor resection via the base of the axilla is difficult because of limited exposure of the axillary content and neurovascular bundle. The authors have used a safe and reliable exposure for these situations. Methods: Between 1980 and 1997, 35 patients underwent extensile exposure of an axillary tumor. Diagnoses included 19 primary and 16 metastatic tumors of the axilla. The axillary cavity was fully exposed via the deltopectoral groove after detachment and reflection of two layers of muscles: first, the pectoralis major and, second, the coracoid origin of the pectoralis minor, cora-cobrachialis, and the short head of the biceps muscle. This surgical approach allowed full tumor visualization and determination of the exact anatomic relation of the tumor to the neurovascular bundle and as a result, tumor respectability. Following resection, the pectoralis minor and conjoined tendons were reattached to the coracoid process with a nonabsorbable suture, and the pectoralis major was reattached to its insertion site on the proximal humerus in the same manner. Results: Exposure revealed a safe plane of dissection between the tumor and the major neurovascular bundle in 23 patients and invasion of the major neurovascular bundle in 12 patients who subsequently underwent a forequarter amputation. At the most recent follow-up, none of these patients had functional limitation, which could be attributed to the extensile approach itself. All patients gained their presurgical pectoralis major and biceps function. Complications in the group of patients that underwent tumor resection included three (13%) superficial wound infections. Due to intended enbloc resection of an involved nerve with the tumor, two nerve palsies (8.7%) were documented. None of the remaining 21 patients had numbness, paresthesias, or nerve pain. There were three (13%) local recurrences; two were managed with wide excision and adjuvant radiation therapy and one necessitated amputation. Conclusions: The extensile exposure of the axilla allows full visualization of axillary tumors. It allows determination of tumor respectability and safe and reliable resection, when indicated. This exposure is associated with good functional outcome and an acceptable morbidity and is recommended in the management of axillary tumors

Introduction Total hip arthroplasty in patients affected by major dysplasia poses great surgical difficulties due to insufficient primary acetabulum, small femoral canal, excessive anteversion of the femoral neck, traction on the neurovascular structures, muscular imbalance that is difficult to restore, and marked epiphyseal rising. In this study we present our experience in lowering and arthroplasty in major hip dysplasia, obtained by shortening osteotomy achieved in a single stage, using techniques designed to diminish possible risks. Materials and methods From 1989 to 2000 we treated 20 patients (27 operations, 7 bilateral) at our institute who were affected by the sequela (lowering of the prosthesis) of Eftekhar Grade-C (11 cases) or Grade-D (16 cases) congenital luxation of the hip. Mean follow-up was 63 months. Clinical results were assessed before and after surgery according to the Merle D’Aubigné method. We also evaluated the presence and degree of Trendelenburg position and the possible use of shoe lifts. The radiographic results of the hip prosthesis were assessed by the Gruen and Dee Lee methods for the stem and cup respectively. Results The mean preoperative clinical score according to the Merle D’Aubigné classification was 3 ± 1 for pain, 3 ± 1 for walking, and 4 ± 2 for movement. The preoperative Trendelemburg position was very marked in all patients. In 18 cases out of 27 a shoe lift was used with a mean height of 60 mm ± 10. We performed a “Z” osteotomy in 14 cases and an oblique osteotomy in 13 cases. The postoperative mean clinical score was 6 ± 1 for pain, 6 ± 1 for walking, and 5 ± 1 for movement. Postoperative Trendelemburg position was present in 19 cases, and 9 cases out of 27 still used a shoe lift with a mean height of 30 mm ± 10. Movement of the cup and stem was observed at 84 months and 112 months’ follow-up respectively, which required revision surgery. Conclusions The choice between oblique and Z osteotomy depends on two parameters: the surgeon’s experience and the extent of femoral resection. Z osteotomy may be more difficult to perform technically, but it enables better adaptation of the prosthesis to the femoral segments for resections over 35 mm. No significant differences in time to unite were observed between oblique and Z osteotomies

Aims

Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis.

Aims

Elective surgery has been severely curtailed as a result of the COVID-19 pandemic. There is little evidence to guide surgeons in assessing what processes should be put in place to restart elective surgery safely in a time of endemic COVID-19 in the community.

Aims

To investigate the benefits of denosumab in combination with nerve-sparing surgery for treatment of sacral giant cell tumours (GCTs).

Patellofemoral complications after TKA are mostly avoided with appropriate operative technique. Although most orthopedic surgeons performed using a medial parapatellar approach at TKA, but a large amount of the patellar blood flow is blocked by this procedure. A certain surgical exposure, including the midvastus and subvastus approach, has resulted in good clinical results. It is important to maintain the integrity of the extensor mechanism. But the southern or subvastus approach has inadequate exposure in some patients. And then we have had the primary total knee Arthroplasty using midvastus approach in 98 cases, 68 patients. Mean follow up is 30 months, between from 20 months to 43 months. We estimated parameters of total blood loss, surgical time, difficulty of exposure, number of lateral releases. The clinical parameters of range of motion, ability to perform a straight leg raise, and the number of operative or postoperative complications were evaluated. The patients who had the midvastus approach had minor blood loss, resonable surgical time, no difficulty of exposure even in patients with severe varus or valgus deformities, required lateral retinacular releases only 5% of the cases. The range of motion was all above 120 degrees flexion, no extension loss, had a higher incidence of ability to straight leg raise and fewer complications as like superficial wound infection. The midvastus surgical approach have some more advantages with less pain and earlier control of the operative leg, and may be discharged from the hospital earlier. Because preserving the integrity of the vastus medialis insertion into the medial border of the quadriceps tendon and limited disruption of the extensor mechanism improves the rapid control of quadriceps muscle and improves the more stable patellofemoral articulation, and then evidenced a marked reduction in the need for lateral retinacular releases. We recommend the mid-vastus surgical approach for total knee arthroplasty. The Midvastus approach is an efficacious alternative to the medial parapatellar approach for primary total knee arthroplasties in selected patients who are not obese and who have not had previous arthrotomy. And if needed more additional exposure, the muscle can be safely split by further dissection