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At least 1,027 records · Page 57Linked to original sources
PubMed2005

Detection of the center of the hip joint in computer-assisted surgery: an evaluation study of the Surgetics algorithm.

OBJECTIVE: The aim of this paper is to assess the accuracy of an algorithm implemented by PRAXIM in the SURGETICS navigation station for detection of the hip center. This study will assess the robustness and accuracy of the algorithm in various clinical situations such as those involving non-sphericity of the femoral head, motion of the pelvis during hip center detection, and restricted range of motion. MATERIALS AND METHODS: The localization of the hip center, based on kinematics, relies on the recording of n successive positions of the femoral rigid body in the localizer reference system during a passive circumduction motion of the hip joint. Therefore, the shape of the clouds of points acquired may vary from one acquisition to the next. To allow a comprehensive study of the consequences of these variations for hip center detection, we developed a simulator to generate numerous clouds of points. Results given subsequently for each test are the values of the difference between the femoral mechanical axis computed with C(c), the computed hip center, and the same axis computed with C(o), the reference hip center. RESULTS: Test 1: Sensitivity to noise. The errors ranged from 3.33 E - 12 (SD 3.29E - 12) for a noise of 0 mm to 8.18E - 1 (SD - 7.05E - 1) for a noise of 15 mm. Test 2: Sensitivity to the shape of the acquisition motion. All trajectories gave an error < 1 degrees . Test 3: Sensitivity to restricted range of motion. No value > 1 degrees was found during this test. Test 4: Sensitivity to the distance between two points of the cloud. No value > 0.5 degrees was found during this test. Test 5: Sensitivity to the number of points included in the cloud. No value > 1 degrees was found during this test. CONCLUSIONS: The Surgetics algorithm is robust to noise, can compensate for pelvic motion, and can be used even in the case of restricted range of motion.

Algorithms↗
PubMed2000

The influence of the acetabular labrum on hip joint cartilage consolidation: a poroelastic finite element model.

The goal of this study was to investigate the influence of the acetabular labrum on the consolidation, and hence the solid matrix strains and stresses, of the cartilage layers of the hip joint. A plane-strain finite element model was developed, which represented a coronal slice through the acetabular and femoral cartilage layers and the acetabular labrum. Elements with poroelastic properties were used to account for the biphasic solid/fluid nature of the cartilage and labrum. The response of the joint over an extended period of loading (10,000s) was examined to simulate the nominal compressive load that the joint is subjected to throughout the day. The model demonstrated that the labrum adds an important resistance in the flow path of the fluid being expressed from the cartilage layers of the joint. Cartilage layer consolidation was up to 40% quicker in the absence of the labrum. Following removal of the labrum from the model, the solid-on-solid contact stresses between the femoral and acetabular cartilage layers were greatly increased (up to 92% higher), which would increase the friction between the joint surfaces. In the absence of the labrum, the centre of contact shifted towards the acetabular rim. Subsurface strains and stresses were much higher without the labrum, which could contribute to fatigue damage of the cartilage layers. Finally, the labrum provided some structural resistance to lateral motion of the femoral head within the acetabulum, enhancing joint stability and preserving joint congruity.

Acetabulum↗
PubMed1989

Hip joint mobility and spinal angles in standing and in different sitting postures.

The spinal angles of 25 female subjects were measured in standing and in four different sitting postures with various trunk-thigh angles. Additionally, measurements of hip and lumbar mobility were made in an attempt to relate mobility to spinal curvature in the different sitting postures. Lumbar curvature was observed to decrease as the trunk-thigh angle decreased across the different sitting postures, and reduction in curvature was associated with hip mobility. An exploratory analysis of interrelationships among hip mobility, spinal mobility, and spinal curvature was also carried out. A significant correlation between lumbar and thoracic angular deviations in standing and hip flexion/extension range was obtained. The findings are discussed with reference to theories of sitting posture and the influence of hip joint mobility on postural adaptations to furniture. Further investigations, including studies of male subjects, are indicated.

Adult↗
PubMed2002

The role of MRI in the evaluation of hip joint disease in clinical subtypes of juvenile idiopathic arthritis.

The purpose of this study was to evaluate the role of MRI in the assessment of hip joint involvement in clinical subtypes of juvenile idiopathic arthritis (JIA). 28 patients (mean age 12.5 years) with JIA (oligoarthritis 8, polyarthritis 13, systemic arthritis 7) were examined with T(2) weighted turbo spin echo and T(1) weighted spin echo (plain and contrast enhanced) sequences. The severity of joint involvement was evaluated using an MR grading score: grade 1=no contrast enhancement; grade 2=focal synovial contrast enhancement; grade 3=diffuse synovial contrast enhancement; grade 4=grade 3+diffuse synovial thickening; grade 5=grade 4+villonodular synovial thickening; and grade 6=grade 5+cartilage and subchondral bone erosions. MRI was abnormal in 57.1% of cases (25% of oligoarthritis, 53.8% of polyarthritis and 100% of systemic arthritis). Clinical examination was positive in 32.1% of cases and was associated with higher MR grades (mean 4.6, SD 1.34) compared with a negative clinical examination, which was associated with lower MR grades (mean 1.78, SD 1.13) (p<0.001). Patients with active disease (mean grade 3.9, SD 2) had higher MR grades than those with inactive disease (mean grade 2.1, SD 1.4) (p<0.01). The MR grades were different in the three clinical subtypes: oligoarticular (mean 1.5, SD 1.06); polyarticular (mean 2.38, SD 1.55); and systemic (mean 4.85, SD 1.21) (F:12.3, p<0.001), with a significant difference between systemic arthritis and oligoarthritis, and between systemic arthritis and polyarthritis (p<0.001). MRI of the hip might be considered for inclusion in the study protocol of patients with JIA since it reveals joint involvement at early stages and provides a detailed evaluation of the extent of joint disease.

Adolescent↗
PubMed1983

Screening of children with congenital dislocation of the hip joint on the maternity wards in Sweden.

In Sweden screening for congenital dislocation of the hip joint (CDH) on the maternity wards was commenced in the 1950s. Of the estimated number of cases with CDH approximately 50% are diagnosed on the maternity wards and 80% during the first 6 months of life. Of the children "missed" at the primary screening on the maternity wards a substantial number have been premature babies treated at the intensive care unit postpartum. X-ray examination at the age of 1.5-3 months has been a helpful tool to reveal failure of early abduction treatment, which has been difficult to detect by clinical examination. Children with neonatal hip instability and a family history of CDH seem to represent a subgroup with an increased risk of failure of primary treatment and may need prolonged abduction treatment. The von Rosen splint has proved to be a reliable brace if used properly. If abduction treatment is commenced already during the first few days of life the risk for avascular necrosis is very low--1%.

Braces↗
PubMed1988

An evaluation of retrieved UHMWPE hip joint cups.

In this study it is demonstrated that the combined chemical and mechanical influences of the implant situation cause property changes of ultra-high-molecular-weight polyethylene (UHMWPE) hip joint cups. Nearly 250 loosened hip cups, retrieved 3 weeks to 14 years after implantation, were investigated. The clinical long-term behavior of various shaped polyethylene hip sockets are statistically analyzed. The main damage features were defined and described. Density measurements show a density increase with implantation time and a dependence of these changes from implant position and loading conditions. The rate of extractable constituents also increases with course of time. An increased in vivo conditioned oxidation of the UHMWPE can be demonstrated by infrared (IR) spectrometry. The density increase can be explained by post-crystallization, which is the result of oxidative chain scission. This leads to a reduction of the average molecular weight of the PE and to an increased extractability of constituents. Since these changes have been recognized as the reasons for aging and failing of UHMWPE, the methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods. Characteristic damage features of hip cups allow direct relationships with construction characteristics and their improvement.

Hip Prosthesis↗
PubMed1990

Giant synovial cyst of the hip joint presenting with femoral vein compression.

A patient is presented with signs mimicking deep venous thrombosis of the leg, which proved to be compression of the femoral vein, without thrombosis, caused by a large cyst from the adjacent hip joint. Clinical presentation, diagnostic imaging procedures and therapy are presented with a review of the literature.

Aged↗
PubMedDate not supplied

The effect of triple pelvic osteotomy on the articular contact area of the hip joint in dysplastic dogs: an in vitro experimental study.

OBJECTIVE: To investigate the effect of triple pelvic osteotomy (TPO) on articular contact area and acetabular coverage of dysplastic hip joints in dogs. STUDY DESIGN: Articular contact area and femoral head coverage by the acetabulum were computed in vitro in normal and dysplastic canine hips. The effect of TPO on articular contact and coverage was then analyzed in the dysplastic hips. Sample Population-Five normal and six dysplastic canine cadaver specimens. METHODS: Contact area and coverage of loaded hips were computed using serial computed tomography scan images before and after TPO. Three angles of acetabular ventroversion (AVV) were studied (20 degrees, 30 degrees, and 40 degrees). Using a custom-designed hinge plate, angles of spontaneous hip reduction in dysplastic hips were compared with previously recorded angles of reduction determined by the Ortolani test. RESULTS: Contact area significantly increased from 0 degrees to 30 degrees of AVV, then remained virtually unchanged. Coverage significantly increased from 0 degrees to 20 degrees of AVV. Both contact and coverage of normal hips were similar, yet significantly smaller than those of dysplastic hips once reduction had occurred. The experimental angles of reduction were significantly smaller and poorly correlated with the angles of reduction determined by the Ortolani test. Although coverage continued to increase with AVV, the actual joint contact area did not significantly vary after relocation of the femoral head. CONCLUSIONS: This study suggests that increasing AVV beyond 20 degrees does not significantly improve the beneficial effects of TPO and therefore should be carefully weighed against increased risks of postoperative complications associated with large angles of AVV.

Analysis of Variance↗
PubMed1992

Polygonal triple osteotomy of the pelvis. A correction for dysplastic hip joints.

A new triple osteotomy, polygonal pelvic osteotomy (PPO), is described for use in dysplastic hips. The hip joint must be congruous with a centre-edge (CE) angle between +20 degrees and -10 degrees. Templates are used before and during operation which allow precise correction of the position of the acetabulum. The geometry of the osteotomy and a special compression plate achieve sufficient stability to permit early mobilisation. Surgery is indicated in adolescents and young adults if pain persists for at least two months. The surgical exposure, operative technique and postoperative management are presented, with the two-year results in nine cases.

Acetabulum↗
PubMed1991

[A case report of cystic adventitial degeneration communicating with the hip joint in the external iliac artery].

Cystic adventitial degeneration is an uncommon cause of arterial obstruction. Its etiology is debated. We report a case in which the left external artery was affected and the cystic mass communicated with the hip joint. The findings of this case support the embryonic theory that the articular synovium and adventitial cysts have the same mesenchymal origin.

Constriction, Pathologic↗
PubMedDate not supplied

[Homografts allogeneic of the knee and hip joints].

The technique and instruments of PAP, Krompecher and Jaros allow a precise preparation of the femoral head, acetabulum, femoral condyles and tibial plateau in the donor and recipient for the application of homograft transplants of joint articular surfaces of 5 millimetre thickness. In the present series, specimens were preserved by freezing at 30 degrees below zero to prevent immunologic reactions in the recipient. Immunogenic control tests in 12 patients have shown that freezing at 30 degrees below zero does not eliminate antigens in the transplant. In future, therefore, it is intended to transplant only cartilage with living cells in relation to the HLA system. The problem of prevention of infection has been solved by a special antibiotic preparation of the specimen. Radiographic examination 4 years after operation shows that only two of 12 patients had an unsatisfactory result. Function in these two hip joints is, however, better than before operation although the transplant has been partly resorbed. The technique of homograft transplantation of the hip and knee joints is suitable for young or middle-aged individuals in whom the only alternative would be an arthrodesis. For older persons a joint prosthesis is preferable.

Adult↗
PubMed1992

[A comparative study of the characteristics of femoral hip prosthesis heads--study and results ceramic-coated hip joint heads of titanium].

Today, only hard/soft cup and femoral head combinations are employed for hip joint prostheses. Highly polished ceramic is a material with very good tribological properties for femoral heads, being highly resistant to mechanical wear and tear, and highly resistant to chemical reactions in the biological environment. The advantage of metal heads, in contrast, undoubtedly lies in their resistance to breakage and the ease with which their geometry can be modified with respect, for example, to antirotation angle and neck length. The ideal material for femoral heads is a combination of the two materials. The new multi-layer combination of titanium-niobium oxide/nitride ceramic coating applied to a prehardened titanium head combines the positive material properties in an ideal manner. Femoral heads made of CoCrMo, oxide-hardened titanium, aluminium oxide or multilayer titanium-niobium ceramic were compared by means of friction an wear and tear tests. The TiNb-ceramic-metal heads showed similar abrasion at the surface as the ceramic heads. At the high loads of more than 400 kp, which may also be reached under physiological conditions, the specially coated titanium-ceramic heads proved to be superior in terms of resistance to fracture and tribological properties.

Biomechanical Phenomena↗