Diagnosis of infection after total hip arthroplasty

Forty-eight total hip arthroplasties for which revision surgery was performed were reviewed to determine the accuracy of laboratory tests, plain radiographs, hip aspiration, and technetium-99m MDP and gallium-67 scans in demonstrating the presence or absence of infection of the prosthesis. Six of the 48 hips were diagnosed as having an infection at the revision surgery. The erythrocyte sedimentation rate and the C-reactive protein levels were significantly higher in the patients with infected prostheses. The difference in the white blood cell count was not significant. There was no significant relationship between the presence of infection and the severity of loosening and instability of the implants diagnosed by plain radiographs. The accuracy of hip aspiration in diagnosing the infection was 83%, with a sensitivity of 40% and a specificity of 92%. The accuracy of technetium-99m MDP bone scan was 79%, with a sensitivity of 83%, and a specificity of 79%. Gallium-67 scan had an accuracy of 96%, a sensitivity of 67%, and a specificity of 100%. The findings in the present study indicated that diagnostic tests consisting of laboratory tests and plain radiography, followed by hip aspiration and sequential use of technetium-99m MDP and gallium-67 scintigraphies, are suitable for differentiation between mechanical loosening and infection of total hip arthroplasty.

Dynamic magnetic resonance imaging of femoral head perfusion in femoral neck fracture

A prospective followup study of 36 femoral neck fractures according to the assessment of femoral head perfusion using dynamic magnetic resonance imaging is reported. Patients were divided into three groups based on the dynamic magnetic resonance imaging findings (dynamic curve pattern and relative enhancement ratio) that were conducted within 48 hours of the injury. Traction was used to achieve anatomic reduction and to prevent additional damage to vascularity until minimally invasive internal fixation could be done. The fractures of all 17 patients whose femoral head perfusion was normal (Type A; n = 11) or was impaired but not totally absent (Type B; n = 6) healed without complications. Among the 19 patients whose femoral head perfusion was absent (Type C), 15 had complications (osteonecrosis, n = 10; nonunion, n = 5). Assuming that fractures with a Type A or Type B curve pattern would unite successfully and that those with a Type C curve pattern would not, the sensitivity, specificity, and accuracy of the predictions of successful osteosynthesis of the femoral neck fractures using this method were 81%, 100%, and 89%, respectively. The current classification of femoral neck fractures using dynamic magnetic resonance imaging may be useful in selecting an appropriate treatment method for the fractures.

[Cardiovascular effects of colforsin daropate hydrochloride for acute heart failure after open heart surgery]

Colforsin daropate hydrochloride (COL) is a novel drug for the treatment of acute heart failure. COL stimulates adenylate cyclase directly and produces positive inotropic and vasodilator effects accompanied by the increase in cellular cAMP. We investigated its cardiovascular effects for 9 patients who showed low cardiac index (< 3.0 l/min/m2) after open-heart surgery in ICU. After 2 or 3 hours from administration of COL, heart rate and cardiac index increased, and pulmonary artery pressure and central venous pressure decreased significantly, but blood pressure and systemic venous oxygen saturation did not show significant change. In conclusion, COL improved hemodynamics through positive inotropic and vasodilator effects without hypotension. We should investigate more proper usage of this drug to avoid such side effects as tachycardia and arrhythmia, which occurred in some cases.

Development of acute myeloid leukemia after chemotherapy for osteosarcoma

The current study describes two patients with osteosarcoma who had acute myeloid leukemia develop after treatment with multiagent chemotherapy. The incidence density for the chemotherapy protocol was 129.8 per 10,000 person-year of followup. Karyotype analysis of 16 reported patients (including the current two patients) indicated that most leukemias after treatment of osteosarcoma correlated with the use of topoisomerase II inhibitors, such as doxorubicin. The deoxyribonucleic acid-damaging activity of doxorubicin reinforced by the use of alkylating agents is highly suspected as a causative event in the development of leukemia after treatment of osteosarcoma. As the next step in the development of treatment for patients with osteosarcoma, the type and intensity of treatment must be evaluated to minimize possible leukemogenic effects without compromising the potential for cure.

Loss of the mitochondrial Hsp70 functions causes aggregation of mitochondria in yeast cells

Ssc1p, a member of the Hsp70 family in the mitochondrial matrix of budding yeast, mediates protein import into mitochondria and prevents irreversible aggregation of proteins in the mitochondrial matrix during folding/assembly or at elevated temperature. Here, we show that functional inactivation of the mitochondrial Hsp70 system causes aggregation of mitochondria. When temperature-sensitive mitochondrial Hsp70 mutant cells were incubated at restrictive temperature, a tubular network of mitochondria was collapsed to form aggregates. Inhibition of protein synthesis in the cytosol did not suppress the mitochondrial aggregation and functional impairment of Tim23, a subunit of mitochondrial protein translocator in the inner membrane, did not cause mitochondrial aggregation. Therefore defects of the Hsp70 function in protein import into mitochondria or resulting accumulation of precursor forms of mitochondrial proteins outside the mitochondria are not the causal reason for the aberrant mitochondrial morphology. By contrast, deletion of Mdj1p, a functional partner for mitochondrial Hsp70 in prevention of irreversible protein aggregation in the matrix, but not in protein import into mitochondria, caused aggregation of mitochondria, which was enhanced at elevated temperature (37°C). The aggregation of mitochondria at 37°C was reversed when the temperature was lowered to 23°C unless protein synthesis was blocked. On the basis of these results, we propose that the mitochondrial matrix contains a protein that is responsible for the maintenance of mitochondrial morphology and requires mitochondrial Hsp70 for its function.

Regional differences in myocardial work of the left ventricle in patients with idiopathic dilated cardiomyopathy: Implications for the surgical technique used for left ventriculoplasty

OBJECTIVES

In this study we measured regional myocardial work of the left ventricle in patients with dilated cardiomyopathy and examined the existence of regional differences in myocardial work.

BACKGROUND

Left ventriculoplasty aims to improve the ejection fraction by excluding a region with decreased wall motion and decreasing wall tension. If regional differences in myocardial work are present, left ventriculoplasty will be more effective when a region with decreased myocardial work is excluded.

METHODS

The study group consisted of 10 patients with idiopathic dilated cardiomyopathy. Regional work of the ventricle normalized to a unit volume of myocardium (RWM) is given as follows: RWM = -integral sigma(d)[ln(1/H)], where sigma is mean wall stress, and H is wall thickness of the region. After right-sided catheterization, left ventricular pressure was measured with a 3F micromanometer catheter. Echocardiography was performed simultaneously, and a short-axis view of the left ventricle at the level of the papillary muscles was obtained. The derived M-mode image was recorded with left ventricular pressure. sigma-ln(1/H) relations for the ventricle were delineated, and regional work of the interventricular septum and posteroinferior wall were determined. Relationships between regional work of the myocardium and wall thickness, interventricular septal regional work of the myocardium and right ventricular systolic pressure, and right ventricular ejection fraction were also studied.

RESULTS

Interventricular septal regional work ranged from -0.84 to 3.34 mJ/cm3 (0.74 +/- 1.51 mJ/cm3). Posteroinferior wall regional work ranged from 1.59 to 4.29 mJ/cm3 (2.77 +/- 0.86 mJ/cm3). In the study group, interventricular septal regional work was lower than posteroinferior wall regional work (P <.05). In 8 of these 10 patients, interventricular septal regional work was lower than posteroinferior wall regional work. In the other 2 patients, conversely, interventricular septal regional work was higher than posteroinferior wall regional work.

CONCLUSIONS

The existence of differences in regional work between the interventricular septum and the posteroinferior wall suggests the importance of the evaluation of regional work in the selection of an effective treatment for dilated cardiomyopathy.

[Postoperative rupture of abdominal aortic aneurysm in patients with ischemic heart disease and other organ disease]

We experienced two cases of rupture of an abdominal aortic aneurysm during the early postoperative period of coronary artery bypass grafting (CABG). A 71-year-old man on hemodialysis (HD) was diagnosed with ischemic heart disease (IHD) and abdominal aortic aneurysm (AAA) of 70 mm in size. After CABG, he developed symptoms of acute pancreatitis and died of rupture of AAA on the 12th postoperative day. A 74-year-old man with early gastric cancer was diagnosed with IHD and AAA of 70 mm. After CABG and gastrectomy, he died of rupture of AAA due to anticoagulant therapy on the 3rd postoperative day. One-stage operation should be performed in patients with IHD, AAA more than 60 mm in size and other organ disease. It is important to control blood pressure and anticoagulant therapy appropriately during the early postoperative period when graft replacement for AAA is not performed simultaneously. Careful observation is required to establish the differential diagnosis of acute pancreatitis and impending rupture of AAA in patients on HD.

Primary Ewing's sarcoma/peripheral primitive neuroectodermal tumor at the vertex of the skull with elevated serum carcinoembryonic antigen: case report

A primary Ewing's sarcoma arising in the skull is relatively rare. Although a small number of case reports noted elevated carcinoembryonic antigen (CEA) in patients with primary central nervous system (CNS) neoplasms, there is no report of Ewing's sarcoma/peripheral primitive neuroectodermal tumor (PNET) with elevated serum levels of CEA. A 7-year-old boy who had episodes of headache and vomiting had noticed a solid mass in the vertex of the head. Imaging studies revealed a large intra- and extracranial tumor at the vertex of the skull. Hematological examination demonstrated high serum levels of CEA: 91.09 ng/ml. The patient initially underwent an embolization of the bilateral middle meningeal arteries with Gelfoam particles. One week later, the patient was operated on and a subtotal resection of the tumor was performed. On histopathological and molecular genetic examination, the tumor was diagnosed as a Ewing's sarcoma/peripheral PNET. Immunohistochemical study showed strongly positive staining for CEA in the tumor cells. The serum level of CEA was normalized at 0.83 ng/ml after the tumor was removed and the boy underwent radiotherapy and 3 courses of chemotherapy. This is the first reported case of a primary Ewing's sarcoma/peripheral PNET at the vertex of the skull with elevated serum CEA.

Reconstruction of the proximal humerus with the clavicle after tumor resection: a case report

Reconstruction of the proximal humerus after resection for tumor and modification of the clavicular transposition procedure is described in which the blood supply of the clavicle is preserved and the clavicle is used to bridge the defect. An 11-year-old boy presented with shoulder pain, and the diagnosis was osteosarcoma of the right proximal humerus. After resection of the sarcomatous proximal humerus, the clavicle was released with its periosteum remaining intact, and the clavicle was rotated downward around the acromioclavicular joint. A vascularized fibula supplemented the reconstruction in trying to gain length of the arm. The acromioclavicular joint and the vascular supply of the clavicle were preserved. Internal fixation from the clavicle and the fibula to the distal humerus was made with an AO plate and screws. Muscles around the proximal humerus were reattached to the clavicle. Range of motion of the shoulder was 80 degrees flexion, 85 degrees abduction, 30 degrees external rotation, and 90 degrees internal rotation. Although the postoperative followup is relatively short, only 2 years, the functional advantages of this operation over other forms of reconstruction can be observed.

Synovial sarcoma with a large hematoma in the inguinal region

We report the case of a patient with synovial sarcoma and a large hematoma of the inguinal region. The patient underwent tumor resection of the lower 2/3 of the acetabulum after preoperative chemotherapy. Twenty-four months after surgery, she is alive without any relapse and can walk without support.

The rabies virion-associated 100-kDa polypeptide (VAP100) is a host-derived minor component of the viral envelope

We investigated a minor polypeptide component of 100-kDa detected in the rabies virion (referred to as VAP100) by using a monoclonal antibody (mAb), #16743, which was shown to recognize the SDS-denatured VAP100 antigen by immunoblot analyses. Although the VAP100 antigen was hardly detectable in the cell by usual immunoblot methods with this mAb, we could detect the antigen by a luminescent immunoblot method as well as by immunoprecipitation from the metabolically radiolabeled cell lysates and virions. Fluorescent antibody (FA) staining with mAb #16743 detected the uniformly distributed antigen on the formalin-fixed normal BHK-21 cells, while slight accumulation of the antigen was also seen in the Golgi area when the cells were permeabilized by treatment with Triton X-100 after fixation. Rabies virus infection induced alteration of the behavior of VAP100 to show a spotted distribution pattern in virus-infected cells. Double FA staining with mAb #16743 and rabbit antibody against the rabies virus envelope antigen demonstrated colocalized distribution of the viral envelope antigens and VAP100 in the cell. From these results, we think that VAP100 is a membrane-associated component of the cell, and its colocalized distribution with the viral envelope antigens in the cell implicates an intimate association of the VAP100 with viral envelope protein(s) and a reflection of possible involvement in the efficient incorporation of VAP100 into the virion.

Simultaneous induction of galectin-3 phosphorylated on tyrosine residue, p21(WAF1/Cip1/Sdi1), and the proliferating cell nuclear antigen at a distinctive period of repair of hepatocytes injured by CCl4

The period of repair of hepatocytes injured by CCl4 and signaling proteins intrinsic to this period were examined. A 30 kDa polypeptide detected by immunoblot analysis using anti-phosphotyrosine antibody in livers from rats 48 to 72 h after administration of a single dose of CCl4 was identified as galectin-3 induced in cytoplasm of periportal hepatocytes and phosphorylated on tyrosine residue(s). Simultaneously, these hepatocytes induced p21(WAF1/Cip1/Sdi1) in the nucleus and the proliferating cell nuclear antigen in both the nucleus and the cytoplasm, suggesting that hepatocytes during this distinctive period are quiescent and repair cellular damage. Trabecular architecture of hepatocytes with the proliferating cell nuclear antigen only in the nucleus was found at 96 h. These findings indicate that galectin-3 is a novel member of signaling proteins downstream of tyrosine kinase, and suggest that it plays roles in supporting repair or survival of the injured hepatocytes rather than their proliferation that is likely to be initiated later than 72 h.

A reverse transcriptase-polymerase chain reaction assay in the diagnosis of soft tissue sarcomas

BACKGROUND

Many types of sarcomas are characterized by specific chromosomal translocations that result in the production of novel chimeric genes. Detection of these fusion genes could be a sensitive molecular diagnostic assay. However, to the authors' knowledge there have been few systemic comparisons between the current histopathologic diagnosis and the presence or absence of particular fusion genes in patients with adult soft tissue sarcomas (STSs).

METHODS

Total RNA was extracted from 75 cases of STS and analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the detection of a variety of fusion transcripts. The results of the molecular assay were compared with standard histopathologic diagnoses.

RESULTS

Of the 18 tumors diagnosed as synovial sarcoma, 17 (94%) expressed SYT-SSX chimeric transcripts. All nine myxoid liposarcomas were positive for FUS-CHOP fusion transcripts. Of the four cases of Ewing sarcoma, two had an EWS-FLI1 fusion transcript and one had an EWS-ERG fusion transcript. A clear cell sarcoma had a EWS-ATF1 fusion transcript. None of 19 cases of malignant fibrous histiocytoma nor 3 leiomyosarcomas contained a fusion transcript. Three cases with an initial diagnosis other than synovial sarcoma expressed a SYT-SSX fusion transcript. A review of the slides and additional examination showed that a diagnosis of synovial sarcoma was appropriate for these cases. There was a trend for biphasic synovial sarcoma to contain the SYT-SSX1 fusion.

CONCLUSIONS

The authors believe RT-PCR assay for the detection of a specific fusion gene provides a useful tool for confirmation of the diagnosis of adult STS in diagnostically difficult cases and in retrospective studies.

Three types of putative presympathetic neurons in the rostral ventrolateral medulla studied with rat brainstem-spinal cord preparation

To study the electrophysiological properties of presympathetic neurons in the rostral ventrolateral medulla (RVLM), intracellular recordings were performed by the whole-cell patch-clamp technique. We utilized the neonatal rat brainstem-spinal cord preparation, in which the sympathetic neuronal network is thought to be preserved, unlike in slice preparation. In response to stimulation in the ipsilateral Th2 spinal segment including intermediolateral cell column (IML), 33 of 151 non-respiratory RVLM neurons showed antidromic action potentials with a constant latency of 45 ms, and can be considered as presympathetic neurons. We classified and characterized the RVLM presympathetic neurons into three types: 'regularly firing neurons (n=7)', which showed ramp depolarization and frequent action potentials (4.2+/-0.9 spikes/s) with rare excitatory postsynaptic potentials (EPSPs); 'irregularly firing neurons (n=21)', which exhibited many EPSPs that modulated the firing rate; and 'silent-type neurons (n=5)', which discharged action potentials only during current-induced depolarization. Lucifer-Yellow staining showed that the irregularly firing neurons were significantly larger and had more dendrites than the regularly firing neurons. All regularly firing neurons retained their discharges during low-Ca2+ -high-Mg2+ superfusion that blocks synaptic input, whereas the discharges in 11 of 16 irregularly firing neurons were abolished, suggesting that the regularly firing neurons discharged independently of synaptic input. Seven of 31 RVLM neurons were hyperpolarized by stimulation of vagal afferent nerves. In summary, three types of RVLM presympathetic neurons were characterized by the patch-clamp technique in the brainstem-spinal cord preparation, in which the connection was preserved from vagal afferent to the Th2 spinal segment through the RVLM. Since antidromic action potentials were demonstrated by stimulation in the Th2 spinal segment in 33 neurons of all three types, all types of RVLM neurons constitute a part of the sympathetic neuronal network.

Expression of connective tissue growth factor in cartilaginous tumors

BACKGROUND

Connective tissue growth factor (CTGF) predominantly is expressed in hypertrophic chondrocytes and its specific receptors are demonstrated on chondrocytic cells. Therefore, CTGF may be involved in the proliferation and/or differentiation of cartilage cells. In the current study, CTGF expression was examined both in chondrosarcoma and enchondroma to clarify the relation between the expression of CTGF and the grade of malignancy.

METHODS

The expression of CTGF and proliferating cell nuclear antigen (PCNA) were analyzed immunohistochemically in 34 cartilaginous tumor specimens. Eighteen tumors were determined to be chondrosarcoma including 8 Grade 1 tumors, 6 Grade 2 tumors, and 4 Grade 3 tumors. The percentage of CTGF positive and PCNA positive cells was quantified using at least 500 cells.

RESULTS

CTGF was expressed in 70.1% of enchondroma cells, 84.0% of Grade 1 chondrosarcoma cells, 53.7% of Grade 2 tumor cells, and 26.8% of Grade 3 tumor cells (rho = -0.501; P = 0.0053). In chondrosarcoma cases, CTGF expression was correlated closely with tumor grade (rho = -0.920; P = 0.0001). There was a strong correlation between PCNA expression and tumor grade (rho = 0.907; P < 0.0001) and a strong negative correlation between CTGF and PCNA expression (rho = -0.493; P = 0.0061). In chondrosarcoma cases, patients with high expression of CTGF (>/= 30%) showed higher overall survival compared with those with low expression (< 30%) (P = 0.004).

CONCLUSIONS

The current study revealed a correlation between the histologic grade of chondrosarcoma and prognosis, and the concomitant association between CTGF immunostaining and tumor grade and prognosis. Therefore, immunohistochemical staining with CTGF is a useful procedure for assessing the tumor grade and clinical course in patients with chondrosarcoma.

Hemodialysis-related subacromial lesion: diagnostic imaging and minimally invasive treatment

BACKGROUND

In an attempt to refine the diagnosis and surgical treatment system for spontaneous shoulder pain in supine position (SPSP) in long-term hemodialysis (LTHD) patients we reviewed shoulders of patients during a 4-year period.

PATIENTS AND METHODS

Clinical findings, imaging findings and operative results (average duration of follow-up was 39 months) on both shoulders of 110 patients (Shigei Hospital, Okayama, Japan) were analyzed to identify the cause of SPSP in order to accurately differentiate it from other shoulder pains, and to select the proper treatment method.

RESULTS

As the hemodialysis period lengthened, increase in the incidence and severity of bone and soft tissue changes (radiolucency, joint destruction, increase of thickness of subacromial bursa and rotator cuff, and synovial proliferation) in the shoulder induced by dialysis-related amyloidosis were noted in roentgenography, ultrasonography and magnetic resonance imaging. SPSP occurred in the LTHD patients. An increase in subacromial bursa and rotator cuff thickness correlated with SPSP. A decrease in subacromial space correlated with change in position and SPSP. An increase of subacromial pressure was judged to be the cause of SPSP, and subacromial decompression by coraco-acromial ligament release was effective for relieving SPSP. When massive synovial proliferation or invasion of granulation tissues was observed in the glenohumeral joint, arthroscopic debridement was necessary.

CONCLUSION

SPSP is a sensitive indicator of a distinct subacromial lesion frequently found in LTHD patients. These lesions can be treated by minimally invasive endoscopic coraco-acromial ligament release, resulting in marked pain relief.

A new human malignant peripheral nerve sheath tumour-cell line, HS-sch-2, harbouring p53 point mutation

Only a few human malignant peripheral nerve sheath tumour (MPNST)-cell lines have been reported, and their characteristics have not been fully established. In this study, we established a new human cell line, HS-Sch-2, from an MPNST of the ordinary type which arose in a 54-year-old woman without von Recklinghausen's disease. This cell line was characterized by chromosome analysis, immunohistochemistry, ultrastructural examination, and direct sequencing of the p53 gene. The HS-Sch-2 cells have grown for more than 48 months in vitro, and exhibited hypotriploid karyotypes with complex chromosome abnormalities lacking a specific pattern. Histological features of the heterotranplanted nude mouse tumours were essentially the same as those of the original MPNST, with positive reactions for S-100 protein and neuron-specific enolase but not for epithelial membrane antigen, fibronectin or CD34. Ultrastructural examination in vivo revealed intricate interdigitation of long cytoplasmic processes and basal lamina-like structures. In addition, direct sequencing of the p53 gene detected a point mutation from CGT to CAT at codon 273 in exon 8. This HS-Sch-2 cell line, which exhibits distinctive morphological characteristics of MPNST and a p53 point mutation, will be useful for biological and pathological investigations of MPNST.

The mammalian peroxin Pex5pL, the longer isoform of the mobile peroxisome targeting signal (PTS) type 1 transporter, translocates the Pex7p.PTS2 protein complex into peroxisomes via its initial docking site, Pex14p

In mammals, two isoforms of the peroxisome targeting signal (PTS) type 1 receptor Pex5p, i.e. Pex5pS and Pex5pL with an internal 37-amino acid insertion, have previously been identified. Expression of either type of Pex5p complements the impaired PTS1 import in Chinese hamster ovary pex5 mutants, but only Pex5pL can rescue the PTS2 import defect noted in a subgroup of pex5 mutants such as ZP105. In this work, we found that Pex5pL directly interacts with the PTS2 receptor Pex7p, carrying its cargo PTS2 protein in the cytosol. Pex5pL, but not Pex5pS, mediated the binding of PTS2 protein to Pex14p by translocating Pex7p, demonstrating that Pex5pL plays a pivotal role in peroxisomal PTS2 import. Pex5p was localized mostly in the cytosol in wild-type CHO-K1 and Pex14p-deficient mutant cells, whereas it accumulated in the peroxisomal remnants in cell mutants defective in Pex13p or the RING family peroxins such as Pex2p and Pex12p. Furthermore, overexpression of Pex14p, but not Pex10p, Pex12p, or Pex13p, caused accumulation of Pex5p in peroxisomal membranes, with concomitant interference with PTS1 and PTS2 import. Therefore, Pex5p carrying the cargoes most likely docks with the initial site (Pex14p) in a putative import machinery, subsequently translocating to other components such as Pex13p, Pex2p, Pex10p, and Pex12p.

Gait characteristics of patients after proximal femoral replacement for malignant bone tumour

We analysed the gait characteristics of 15 patients with prosthetic reconstruction of the proximal femur after resection of a malignant bone tumour using stride analysis and measurement of oxygen consumption. Compared with normal volunteers their gait was slower, with less cadence and reduced stride length. The mean net energy cost of free walking was 141% of normal. The degree of asymmetry of the single-limb support time correlated with the free-walking velocity and the net energy cost. If they used a single cane the subjects walked with less cadence, longer stride length, and prolonged single-limb support times. The net energy cost of walking and asymmetry of the single-limb support time had a negative correlation with the strength of the hip abductor muscles. Their walking performance was better than that of six subjects who had hip disarticulation.

Gait characteristics of patients after proximal femoral replacement for malignant bone tumour

We analysed the gait characteristics of 15 patients with prosthetic reconstruction of the proximal femur after resection of a malignant bone tumour using stride analysis and measurement of oxygen consumption. Compared with normal volunteers their gait was slower, with less cadence and reduced stride length. The mean net energy cost of free walking was 141% of normal. The degree of asymmetry of the single-limb support time correlated with the free-walking velocity and the net energy cost. If they used a single cane the subjects walked with less cadence, longer stride length, and prolonged single-limb support times. The net energy cost of walking and asymmetry of the single-limb support time had a negative correlation with the strength of the hip abductor muscles. Their walking performance was better than that of six subjects who had hip disarticulation.