Optimal orientation of the acetabular cup is vital issue not only for primary but revision total hip arthroplasty (THA). Especially in revision THA, malorientation of the cup is likely to occur because anatomical landmark around acetabular rim often disappeared by the osteolytic bony destruction or the process of cup removal. As a consequence, higher dislocation rate and accelerated wear of bearing surface compared with primary THA, which affect the outcome of revision THA, are concerned. On the other hand, computer aided navigation system has been developed in recent years because of substantial errors of manual technique in cup placement even with experienced surgeon. The purpose of this study was to evaluate the accuracy of the cup orientation in revision cementless THA using CT based navigation system. Thirteen patients who underwent revision cementless THA with CT based navigation system (Stryker Japan) were employed for this study. The average age at surgery was 64 years (range, 45–78 years, 3 men and 11 women). Primary surgery was cementless THA in 4 and BHA in 9 hips. Disorder which led to revision THA was loosening of the cup, massive retroacetabular osteolysis, and severe proximal migration of bipolar outer head. In most cases, acetabular rim was not conserved. After removal of the cup or outer head, we revised acetabular components with cementless hemispherical TriAD cups (Stryker Japan) using direct lateral approach in lateral decubitus position. For all the patients, post-operative CT scans were performed and the cup inclination and anteversion angle were measured using 3D image-processing software (Stryker, Japan). The difference between the intra-operative target angle and the angle measured from the post-operative CT image were calculated.Introduction
Materials and Methods
Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination. We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis.Introduction
Materials and methods
Hip Arthrodesis had been considered as a useful surgical option in young adult patient with high activity demands suffering from osteoarthritis of the hip. Although the procedure surely eliminates pain of the hip joint, it can also cause disorders of the adjacent joints in addition to the complete loss of motion, might consequently deteriorate the activity of daily living. The purpose of this retrospective study was to investigate the efficacy and drawback of hip arthrodesis, focusing on the effect of this procedure on the adjacent joints. From 1976 to 1989, 29 hip arthrodesis were performed and 22 hips were followed up (1 died, 6 lost). Disorders led to arthrodesis were septic arthritis (1 hip), post-traumatic (1), osteonecrosis (1), primary osteoarthritis (3), and secondary osteoarthritis due to DDH (16). The average age at surgery was 38 years (range, 19–53 years, 6 men and 16 women). Hip arthrodesis was indicated for young active adults with end stage osteoarthritis, who had normal or mild osteoarthritis in contralateral hip and needed physical labor. The hip was positioned in 30 degrees of flexion, 0 to 5 degree of external rotation, and 0 to 5 degree of abduction. Clinical and radiographic assessment was done for these patients. The clinical follow-up consisted of questionnaire which assessed ability of typical Japanese daily living movement and patient's satisfaction. The condition of the adjacent joints was evaluated clinically and radiographically.Introduction
Materials and Methods
Vascular injury associated with hip surgery is a rare but serious complication. Hip surgeons need to understand the vascular anatomy around the acetabulum to avoid vascular injury. The aim of this study was to visualize the pelvic vascular structures thorough the osseous acetabulum using 3DCT angiography and to describe the three-dimensional relationship between the vessels and the acetabulum. A total of 100 patients who took 3DCT with intravenous contrast for intra-pelvic neoplastic disease were randomly chosen. Those patients with hip disease were excluded. Three examinations were performed. First, dual-phase helical CT data were transferred to a workstation (M900;Zio,Tokyo,Japan) and 3D visualizations of the vascular structures through the pelvis were reconstructed. Second, location of the external iliac, femoral and obturator vessels were investigated in axial CT images. Finally, influence of the age factor on the anatomical courses of the external iliac vessels was assessed. Reconstructed 3D images were able to provide spatial relationship between courses of the pelvic vascular structures and the acetabulum. We could visualize the pelvic vascular structures thorough the pelvis from similar operative viewpoints. Axial CT examinations revealed the external iliac vessels locate very closely to the pelvis as they exit the pelvic cavity. Especially, the left side vessels and vein were closer to the pelvis. The femoral vessels became closer to the acetabular edge with traveling distally. At the distal half of the acetabulum, the femoral vessels located just ventrally to the anterior acetabular edge. The obturator vessels courses inferiorly along the quadrilateral surface behind the acetabulum, they became very close to the inner cortex or the acetabulum. Straight type of the anatomical course of the external iliac vessels was the most common configuration in young patients, curved and the tortuous types were present in older patients. The results of this study are useful to understand the anatomical orientation of the vessels around the acetabulum. To avoid vascular injuries in hip surgery, knowledge of the vascular orientation is of critical importance for the hip surgeon.
Lumbar spondylolysis is a stress fracture of the pars interarticularis. We have evaluated the site of origin of the fracture clinically and biomechanically. Ten adolescents with incomplete stress fractures of the pars (four bilateral) were included in our study. There were seven boys and three girls aged between 11 and 17 years. The site of the fracture was confirmed by axial and sagittal reconstructed CT. The maximum principal tensile stresses and their locations in the L5 pars during lumbar movement were calculated using a three-dimensional finite-element model of the L3-S1 segment. In all ten patients the fracture line was seen only at the caudal-ventral aspect of the pars and did not spread completely to the craniodorsal aspect. According to the finite-element analysis, the higher stresses were found at the caudal-ventral aspect in all loading modes. In extension, the stress was twofold higher in the ventral than in the dorsal aspect. Our radiological and biomechanical results were in agreement with our clinical observations.
The effect of rheumatoid arthritis on the anatomy of the cervical spine has not been clearly documented. We studied 129 female patients, 90 with rheumatoid arthritis and 39 with other pathologies (the control group). There were 21 patients in the control group with a diagnosis of cervical spondylotic myelopathy, and 18 with ossification of the posterior longitudinal ligament. All had plain lateral radiographs taken of the cervical spine as well as a reconstructed CT scan. The axial diameter of the width of the pedicle, the thickness of the lateral mass, the height of the isthmus and internal height were measured. The transverse diameter of the transverse foramen (d1) and that of the spinal canal (d2) were measured, and the ratio d1/d2 calculated. The width of the pedicles and the thickness of the lateral masses were significantly less in patients with rheumatoid arthritis than in those with other pathologies. The area of the transverse foramina in patients with rheumatoid arthritis was significantly greater than that in the other patients. The ratio of d1 to d2 was not significantly different. A high-riding vertebral artery was noted in 33.9% of the patients with rheumatoid arthritis and in 7.7% of those with other pathologies. This difference was statistically significant. In the rheumatoid group there was a significant correlation between isthmus height and vertical subluxation and between internal height and vertical subluxation.
It has been noted that bony union of a pars defect can be achieved in children if they wear a trunk brace. Our aim was to evaluate how the stage of the defect on CT and the presence or absence of high signal change in the adjacent pedicle on T2-weighted MRI were related to bony healing. We treated 23 children conservatively for at least three months. There were 19 boys and four girls with a mean age of 13.5 years (7 to 17). They were asked to refrain from sporting activity and to wear a Damen soft thoracolumbosacral type brace. There were 41 pars defects in 23 patients. These were classified as an early, progressive or terminal stage on CT. The early-stage lesions had a hairline crack in the pars interarticularis, which became a gap in the progressive stage. A terminal-stage defect was equivalent to a pseudarthrosis. On the T2-weighted MR scan the presence or absence of high signal change in the adjacent pedicle was assessed and on this basis the defects were divided into high signal change-positive or -negative. Healing of the defect was assessed by CT. In all, 13 (87%) of the 15 early defects healed. Of 19 progressive defects, only six (32%) healed. None of the seven terminal defects healed. Of the 26 high signal change-positive defects 20 (77%) healed after conservative treatment whereas none of the high signal change-negative defects did so. We concluded that an early-stage defect on CT and high signal change in the adjacent pedicle on a T2-weighted MR scan are useful predictors of bony healing of a pars defect in children after conservative treatment.
This study was undertaken to elucidate the mechanism of biological repair at the tendon-bone junction in a rat model. The stump of the toe flexor tendon was sutured to a drilled hole in the tibia (tendon suture group, n = 23) to investigate healing of the tendon-bone junction both radiologically and histologically. Radiological and histological findings were compared with those observed in a sham control group where the bone alone was drilled (n = 19). The biomechanical strength of the repaired junction was confirmed by pull-out testing six weeks after surgery in four rats in the tendon suture group. Callus formation was observed at the site of repair in the tendon suture group, whereas in the sham group callus formation was minimal. During the pull-out test, the repaired tendon-bone junction did not fail because the musculotendinous junction always disrupted first. In order to understand the factors that influenced callus formation at the site of repair, four further groups were evaluated. The nature of the sutured tendon itself was investigated by analysing healing of a tendon stump after necrosis had been induced with liquid nitrogen in 16 cases. A proximal suture group (n = 16) and a partial tenotomy group (n = 16) were prepared to investigate the effects of biomechanical loading on the site of repair. Finally, a group where the periosteum had been excised at the site of repair (n = 16) was examined to study the role of the periosteum. These four groups showed less callus formation radiologically and histologically than did the tendon suture group. In conclusion, the sutured tendon-bone junction healed and achieved mechanical strength at six weeks after suturing, showing good local callus formation. The viability of the tendon stump, mechanical loading and intact periosteum were all found to be important factors for better callus formation at a repaired tendon-bone junction.
Lumbar spondylolysis can heal with conservative treatment, but few attempts have been made to identify factors which may affect union of the defects in the pars. We have evaluated, retrospectively, the effects of prognostic variables on bony union of pars defects in 134 young patients less than 18 years of age with 239 defects of the pars who had been treated conservatively. All patients were evaluated by CT scans when first seen and more than six months later at follow-up. The results showed that the spinal level and the stage of the defects were the predominant factors. The site of the defects in the pars, the presence or development of spondylolisthesis, the condition of the contralateral pars, the degree of lumbar lordosis and the degree of lumbar inclination all significantly affected union.
Recent studies of the fibroblast growth factor receptor 3 (FGFR3) gene have established that achondroplasia and hypochondroplasia are allelic disorders of different mutations. To determine whether the genotype could be distinguished on the basis of the phenotype, we analysed height, arm span, and skeletal radiographs from 23 patients with achondroplasia and the G380R mutation of FGFR3 and eight with hypochondroplasia and the N540K mutation. Both conditions share the classical pathological features of micromelic short stature, reduced or unchanged interpedicular distances in the lumbar spine, disproportionately long fibulae, and squared and shortened pelvic ilia. These were significantly more severe in the G380R patients than in the N540K patients. Our findings have shown a firm statistical correlation between the genotype and the phenotype, although there were a few exceptional cases in which there was phenotypic overlap between the two conditions.
We used the Ilizarov method in seven patients with severe congenital radial club hands who had had previous wrist surgery, to correct residual shortening and bowing of the ulna together with recurrent wrist deformity. The mean age at operation was 6.5 years. The mean ulnar shortening was 5.3 cm and the mean angular deformity 42°. The mean length gained was 51% of the original ulna. The mean healing index was 46.9 days (29.8 to 64.0). The ratio of the length of the lengthened ulna to the normal side improved on average from 64% to 95%. The angular deformity was initially completely corrected in six out of seven patients. The length ratio, however, decreased to 83% at the final follow-up. In four patients, the angular deformity partially recurred. We recommend correction of congenital radial club hand by staged procedures. The first is centralisation and stabilisation of the wrist and the second lengthening of the ulna and correction of the angular deformity using the Ilizarov method.
We developed a rat model of limb lengthening to study the basic mechanism of distraction osteogenesis, using a small monolateral external fixator. In 11-week-old male rats we performed a subperiosteal osteotomy in the midshaft of the femur with distraction at 0.25 mm every 12 hours from seven days after operation. Radiological and histological examinations showed a growth zone of constant thickness in the middle of the lengthened segment, with formation of new bone at its proximal and distal ends. Osteogenic cells were arranged longitudinally along the tension vector showing the origin and the fate of individual cells in a single section. Typical endochondral bone formation was prominent in the early stage of distraction, but intramembraneous bone formation became the predominant mechanism of ossification at later stages. We also showed a third mechanism of ossification, ‘transchondroid bone formation’. Chondroid bone, a tissue intermediate between bone and cartilage, was formed directly by chondrocyte-like cells, with transition from fibrous tissue to bone occurring gradually and consecutively without capillary invasion. In situ hybridisation using digoxigenin-11-UTP-labelled complementary RNAs showed that the chondroid bone cells temporarily expressed type-II collagen mRNA. They did not show the classical morphological characteristics of chondrocytes, but were assumed to be young chondrocytes undergoing further differentiation into bone-forming cells. We found at least three different modes of ossification during bone lengthening by distraction osteogenesis. We believe that this is the first report of such a rat model, and have shown the validity of in situ hybridisation techniques for the study of the cellular and molecular mechanisms involved in distraction osteogenesis.
In an attempt to repair articular cartilage, allograft articular chondrocytes embedded in collagen gel, were transplanted into full-thickness defects in rabbit articular cartilage. Twenty-four weeks after the transplantation, the defects were filled with hyaline cartilage, specifically synthesising Type II collagen. These chondrocytes were autoradiographically proven to have originated from the transplanted grafts. Assessed histologically the success rate was about 80%, a marked improvement over the results reported in previous studies on chondrocyte transplantation without collagen gel. By contrast, the defects without chondrocyte transplantation healed with fibrocartilage. Immunological enhancement induced by transplanted allogenic chondrocytes or collagen was not significant at eight weeks after treatment, so far as shown by both direct and indirect blastformation reactions. Thus, allogenic transplantation of isolated chondrocytes embedded in collagen gel appears to be one of the most promising methods for the restoration of articular cartilage.
The histology and mechanics of leg lengthening by callus distraction were studied in 27 growing rabbits. Tibial diaphyses were subjected to subperiosteal osteotomy, held in a neutral position for 10 days and then slowly distracted at 0.25 mm/12 hours, using a dynamic external fixator. Radiographs showed that the gap became filled with callus having three distinct zones. Elongation appeared to occur in a central radiolucent zone; this was bounded by two sclerotic zones. Histologically, the radiolucent zone consisted of longitudinally arranged cartilage and fibrous tissue while the sclerotic zones were formed by fine cancellous bone. New bone occasionally contained islands of cartilage, suggesting it had been formed by endochondral ossification. After completion of distraction, the two sclerotic zones fused, shrank and were eventually absorbed, leaving tubular bone with a new cortex. When the periosteum had been removed at the operation, callus formation was markedly disturbed and there was failure of bone lengthening. Scraping of endosteum, in contrast, did not have a pronounced effect. These results suggest that the preservation of periosteum is essential if bone lengthening by callus distraction is to succeed, and that preservation of the periosteum is more important than careful corticotomy.
