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PubMed2002

Alumina-alumina artificial hip joints. Part II: characterisation of the wear debris from in vitro hip joint simulations.

Until recently it was not possible to reproduce clinically relevant wear rates and wear patterns in in vitro hip joint simulators for alumina ceramic-on-ceramic hip prostheses. The introduction of microseparation of the prosthesis components into in vitro wear simulations produced clinically relevant wear rates and wear patterns for the first time. The aim of this study was to characterise the wear particles generated from standard simulator testing and microseparation simulator testing of hot isostatically pressed (HIPed) and non-HIPed alumina ceramic-on-ceramic hip prostheses, and compare these particles to those generated in vivo. Standard simulation conditions produced wear rates of approximately 0.1 mm3 per million cycles for both material types. No change in surface roughness was detected and very few wear features were observed. In contrast, when microseparation was introduced into the wear simulation, wear rates of between 1.24 (HIPed) and 1.74 mm3 per million cycles (non-HIPed) were produced. Surface roughness increased and a wear stripe often observed clinically on retrieved femoral heads was also reproduced. Under standard simulation conditions only nanometre-sized wear particles (2-27.5 nm) were observed by TEM, and it was thought likely that these particles resulted from relief polishing of the alumina ceramic. However, when microseparation of the prosthesis components was introduced into the simulation, a bi-modal distribution of particle sizes was observed. The nanometre-sized particles produced by relief polishing were present (1-35nm). however, larger micrometre-sized particles were also observed by both transmission electron microscopy (TEM) (0.021 microm) and scanning electron microscopy (SEM) (0.05-->10 microm). These larger particles were thought to originate from the wear stripe and were produced by trans-granular fracture of the alumina ceramic. In Part I of this study, alumina ceramic wear particles were isolated from the periprosthetic tissues from around Mittelmeier ceramic-on-ceramic hip prostheses. Characterisation of the particles by TEM and SEM revealed a bi-modal size distribution. SEM analysis revealed particles in the 0.05-3.2 microm size range. and TEM revealed particles in the 5-90 nm size range, indicating that microseparation of the prosthesis components may be a common event in vivo. This study (Part II) has revealed that the introduction of microseparation of the prosthesis components during the swing phase of the wear simulation reproduced clinically relevant wear rates, wear patterns and wear particles in in vitro hip joint simulators.

Aluminum Oxide↗
PubMed2005

Study of hip joint dislocation after total hip arthroplasty.

The present study was undertaken to identify the factors responsible for hip joint dislocation after total hip arthroplasty, laying emphasis on analysis of the background variables of the patients. Of the 317 hips included in the study, ten (3.2%) dislocated. Only the anteversion angle of the cup differed significantly between the dislocation group and the dislocation-free group. The safe zone of the anteversion angle seems to be between 20 and 30 degrees. but it is also essential to set the antetorsion angle of the stem to match the shape of individual bones to create a more stable hip joint. This safe zone may be expanded by the additive effect of antetorsion angle of the stem.

Adult↗
PubMed2003

Articulated distraction of the hip joint in the treatment of benign aggressive tumors located around the hip joint.

INTRODUCTION: The proximal femur and acetabulum are frequent sites for benign active and aggressive lesions. The risk of pathologic fracture is great when a bone-destroying pathology involves an anatomic location such as the hip joint that undergoes profound mechanical loading. If the destruction involves a large area around the joint, secure fixation cannot be achieved with internal fixation implants. The study investigates use of articulated hip distraction to protect reconstructions performed for the treatment of benign active or aggressive tumors presenting with pathologic fracture. PATIENTS AND METHODS: Five patients with a pathologic fracture of the proximal, intracapsular femur or the acetabulum were operated on at the authors' institution between 1997 and 1999. Following histopathologic approval of a benign tumor, all lesions were curetted, chemocauterized, and grafted and osteosynthesis was performed. The reconstruction was protected with an articulated hip distraction external fixator. All patients were mobilized in the immediate postoperative period. RESULTS: The patients were kept in external fixators for an average of 19.8 weeks (range: 16-24). The fixator was removed when bony consolidation was observed in anteroposterior and lateral x-rays of the lesion. The patients were followed for an average of 47 months (range: 38-56) after frame removal. None of the lesions recurred. At the last follow-up examination, all patients displayed an excellent function according to the Musculoskeletal Tumor Society Rating Scale. CONCLUSION: According to the authors' knowledge, this investigation is the first in the literature describing the use of articulated joint distraction in the treatment of benign active and aggressive lesions around the hip joint. The procedure adopts principles of joint distraction into bone tumor surgery.

Acetabulum↗
PubMed1975

[Biomechanics of the hip joint. I. A new model for the calculation of the forces in the hip joint].

After a short review of the theory of the forces acting in the human hip joint we develope a new model for the calculation of the forces R acting on the head of the supporting femur, of their direction phi and of the maximal pressure of the femoral head. The new concept is the determination of a fixed point A, the attachement of the resultant muscle force M at the pelvis, and the insertion T of this muscle force at the trochanter. After determination of this points in a single standard radiography of the pelvis and hips, the model calculate the resultant force R at the hip joint. The pressure in the articulation is calculated also by the same proceeding. The influence of the choice of the point A is discussed.

Biomechanical Phenomena↗
PubMed1996

Aspiration of the hip joint before revision total hip arthroplasty. Clinical and laboratory factors influencing attainment of a positive culture.

The value of routine aspiration of the hip joint before revision of a hip arthroplasty remains controversial. We reviewed the results of such aspirations in an attempt to determine clinical or laboratory factors that could help the surgeon to identify hips that are infected and that should be aspirated preoperatively. One hundred and fifty consecutive revision total hip arthroplasties were performed by one of us. Preoperative aspiration was not performed or data were excluded for eight hips; no fluid was obtained from one of these hips (0.7 percent of the 150). Of the remaining 142 hips, 128 had preoperative aspiration once and fourteen, twice. Twenty-one (15 percent) of the 142 hips were infected, as demonstrated by the intraoperative culture. The intraoperative culture for two of these hips, however, was considered to be false-positive. The initial aspiration was considered to be positive only if an organism grew on the solid medium or if grossly purulent fluid was obtained. The initial aspiration was positive for nineteen hips; on culture of specimens from one hip, Bacteroides thetaiotaomicron grew in the liquid medium only; and purulent fluid was obtained from one hip but no organisms grew on culture. Fourteen aspirations were repeated for various reasons, most commonly to confirm the presence of an unusual organism. The repeat aspiration did not change the diagnosis for these hips. When the two hips with a false-positive intraoperative culture were excluded, preoperative aspiration had a sensitivity of 92 percent, a specificity of 97 percent, and an accuracy of 96 percent. Seventeen of the nineteen truly infected hips were associated with an abnormally elevated erythrocyte-sedimentation rate (mean, 80.8 millimeters per hour). However, fifty-eight (50 percent) of the 116 hips that were not infected, and for which the results were available, also had an abnormally elevated erythrocyte-sedimentation rate (mean, 32.0 millimeters per hour). This difference was significant (p = 0.001, Fischer exact test). The peripheral leukocyte count was not helpful in predicting infection. Hips in which the implants had been in situ for more than five years were less likely to be infected (p = 0.008, Fisher exact test) than those in which the implants had been in situ for five years or less. None of the infected hips in which the implants had been in situ for more than five years were associated with a normal erythrocyte-sedimentation rate. In this study, preoperative aspiration of the hip joint had an excellent sensitivity and specificity with regard to the prediction of infection, On the basis of our findings, we now favor a selective approach to aspiration, as determined by the erythrocyte sedimentation rate and the amount of time that the implant has been in situ.

Adult↗
PubMed2004

[Imaging methods of examining the hip joint].

The hip joint is a synovial joint of the appendicular skeleton which constituents of articular cartilage, subchondral bone plate, articular capsule synovial membrane which produces synovial fluid. Ankylosing spondylitis is chronic inflammatory disorder of unknown cause that affects the axial and appendicular skeleton. Alterations occur in synovial and cartilaginous joints and sites of tendon and ligament attachment to bone.

Hip Joint↗
PubMed1990

[Clinical and radiologic status of the hip joint in adolescents and children with late detection of anomalies of the hip joint].

The study analyzed 35 questionnaires (70 hips) with an overdue discovered anomaly of the hip joint. 32 cases (91.5%) were girls, 3 cases (8.5%) boys, while the relation of girls to boys was 10.6:1. The average age at the moment of discovery of the defect was 3.9 months and in the period of control 12-13 years. All the questionnaires were conservatively treated but it was not observed that the method of treatment had any influence on the final result. According to analysis of clinical and radiological parameters the authors accepted the thought that these hips should be followed up until the end of their growth, and when an indication for operative treatment has been set it should take care about the development of the acetabulum as well as the shape of the proximal edge of the femur and the orientation of the ilium bone.

Adolescent↗
PubMed1993

The value of aspiration of the hip joint before revision total hip arthroplasty.

The role of aspiration of the hip joint before revision of a total hip arthroplasty remains controversial. To address this issue, we reviewed the results of 270 consecutive hips in which aspiration had been attempted before revision procedures that were performed between 1980 and 1988. All hips had intraoperative findings and clinical follow-up of at least two years to confirm the presence or absence of infection. Only six (2 per cent) of the 270 hips were determined to be infected. Aspiration had been attempted in all six hips, but fluid could be obtained from only four. All six hips also had clinical or radiographic signs, or both, of infection, including increasing pain within three years after the arthroplasty (four hips), inability of the patient to attain pain-free status after the original procedure (four hips), radiographic findings compatible with infection (six hips), and a positive finding on culture of a specimen obtained from a previous aspiration (two hips). Because of these factors, aspiration was attempted a second time in four of the six hips and a third time in three of the four. The four hips from which fluid could be obtained had a total of ten successful aspirations; the cultures of specimens obtained from six of these procedures were positive and those from four were negative. The appearance of the capsular tissue at the time of the operation suggested infection in five of the six infected hips. Histological sections were positive for inflammation in all six: there was acute inflammation only in one, chronic inflammation only in two, and acute and chronic inflammation in three. No organisms were seen on gram stains of specimens from any of the six infected hips. Of the 254 hips that did not have an infection and had been aspirated successfully, thirty-two (13 per cent) had a false-positive result on culture of a specimen of the aspiration fluid. Only two (6 per cent) of the thirty-four hips that had a positive result on culture of fluid from the initial aspiration had a true-positive result. No hip had a true-positive result on culture of fluid that had been aspirated preoperatively without also having clinical and radiographic evidence of infection. On the basis of these findings, we recommend that aspiration be performed in selected patients rather than routinely. It also should be performed only if a detailed clinical history suggests infection or if radiographs demonstrate focal lysis, aggressive non-focal lysis, or periostitis.

Aged↗
PubMed1999

A multi-station hip joint simulator study of the performance of 22 mm diameter zirconia-ultra-high molecular weight polyethylene total replacement hip joints.

The commissioning of a new form of 10-station hip joint simulator is described and the results of a study of the performance of zirconia-ultra-high molecular weight polyethylene (UHMWPE) total replacement hip joints in the familiar Charnley head size of 7/8 inch (22.225 mm) diameter are presented. The head size is referred to as 22 mm for brevity and consistency throughout the paper. The simulator provided very consistent and repeatable results and the new machine, together with the methods of investigation adopted, offer an excellent facility for the further evaluation of existing and new prostheses. The findings are compared with the outcome of previous laboratory simulator and clinical studies of ceramic-polyethylene implants of similar diameter. It was found that a relatively rapid penetration of the head into the cup was followed by a very low, steady, long-term penetration rate after about two million loading cycles. The mean long-term volumetric penetration rate was 6.28 mm3/10(6) loading cycles. When the linear penetration rates were assessed by direct measurement on a coordinate measuring machine, or deduced from the tunnelling expression, the resulting values were very similar and small at 0.019 and 0.016 mm/10(6) loading cycles respectively. It is generally assumed that one million loading cycles is equivalent to about one year of service in the body and if this equivalence is accepted, these penetration rates compare very favourably with a clinical evaluation of alumina heads of the same diameter, which yielded a mean long-term penetration rate of 0.022 mm/year.

Aluminum Oxide↗
PubMed1982

Amyloid deposits in human hip joints. A macroscopic, light and polarization microscopic and electron microscopic study of congophilic substance with green dichroism in hip joints.

The occurrence of amyloid in capsular tissue and cartilage from human hip joints were studied by the macroscopic iodine/sulphuric acid test, by light and polarization microscopy, and finally by electron microscopy. It is concluded that the congophilic substance with green dichroism, which in an earlier light and polarization microscopic study was found in a large percentage of hip joints of elderly persons, is amyloid.

Aged↗
PubMed1994

Resultant hip joint force after total hip replacement.

Bending moments acting on the LIMA-LTO femoral stem were calculated using a 3D mathematical model of the hip in the one-legged stance based on muscle anatomical data. The effects of 1 cm medialization and lateralization of the hip joint rotation centre (RC) on the bending moments were determined for different body weights. It was found that the bending moments and hence the stem loosening incidence are higher in lateralization compared to medialization of the RC. In order to diminish the bending moments, body weight should be reduced.

Biomechanical Phenomena↗
PubMed1993

Friction and lubrication in cushion form bearings for artificial hip joints.

Two hip joint prostheses were designed and constructed to be elastohydrodynamically equivalent producing approximately equal initial contact areas and theoretical film thicknesses. One was made from conventional UHMWPE (ultra-high molecular weight polyethylene) and the other was a cushion component which had a low modulus layer introduced into the joint space. Friction measurements were carried out on a pendulum simulator apparatus and the two joints were compared. In addition the experimental results were compared with theoretical values of friction predicted from elastohydrodynamic lubrication theory. Values for the friction factor at peak load and peak velocity in the cushion cup (0.003-0.009) were much lower than in the UHMWPE cup (0.017-0.042). The low friction values in the cushion cup are consistent with fluid film lubrication in the contact with the thin lubricating film being preserved by microelastohydrodynamic action.

Friction↗
PubMed2004

The relationship of hip joint space to self reported hip pain. A survey of 4.151 subjects of the Copenhagen City Heart Study: the Osteoarthritis Substudy.

OBJECTIVES: (1) To evaluate the effect of pelvic orientation on measurements of hip joint space widths (JSW) in cadaver pelvic radiographs, thereby validating the pelvic radiographs of the Copenhagen City Heart Study: The Osteoarthritis Substudy (CCHS III) cohort of 4.152 subjects, and (2) to investigate the relationship between minimal JSW and self reported hip pain of the cohort. METHODS: (1) Cadaver pelves and proximal femora of one male and one female donor were mounted in holding devices permitting independent rotation (total arc of 42 degrees), and inclination/reclination (total arc of 24 degrees). At each 3 degrees increment an anteroposterior radiograph was recorded. Measurements of JSW were performed. (2) Self reported recurrent pain in or around the hip joint during 12 months prior to baseline examinations, and minimum JSW in pelvic radiographs of the cohort were registered. Relationships between minimum JSW and self reported pain were investigated. RESULTS: (1) Measurements of hip JSW in cadaver radiographs were not influenced significantly by rotation. Measurements of JSW were inconclusively influenced by varying inclination/reclination. (2) Minimum JSW< or =2.0 mm was significantly associated to self reported pain in or around the hip joint in both sexes. CONCLUSION: Measurements of minimum hip JSW did not seem to be significantly influenced by varying spatial orientation of the pelvis during X-ray recordings. An inclusion criteria of minimum JSW< or =2.0 mm designating definite degenerative pathology in hips will be used by the current authors in future studies.

Adult↗
PubMed1995

[The magnetic resonance tomographic optimization of hip joint cartilage visualization by the selection of a T1-volume gradient-echo sequence and the use of hip-joint traction].

PURPOSE: The purpose of this study was to examine the accuracy of MR imaging of the healthy and the arthrotically altered articular hip cartilage with in vivo and in vitro separation of femoral head cartilage and acetabular cartilage. MATERIAL AND METHODS: Images of three animal cadaver hips, 8 dissected patient femoral heads and 18 hip joints of human corpses, all either with arthrosis stage I-III or artificial cartilage defects, were compared with their corresponding anatomic sections. Additional histomorphologic examinations of the arthrotic cartilages were conducted, and MR-Imaging of 20 healthy and 21 arthrotic patient hips was performed using a specific traction method. RESULTS: Using a T1-weighted 3-dimensional gradient-echo sequence and a traction of the hip joint, it was possible due to the low-signal imaging of the joint space to separate in vivo the high-signal femoral head cartilage from the high-signal acetabular cartilage. In horizontal position of the phase-encoding parameter, minimisation of the chemical-shift artifact, mainly in the ventro-lateral areas, was accomplished. MRI measurements of the articular cartilage widths showed significant correlations (p < 0.001) with the corresponding anatomic sections. At the same time the T1 3-dimensional gradient-echo sequence of the lateral femoral head with r = 0.94 showed the lowest deviations of the measurements. It was possible with MR imaging to distinguish four cartilage qualities. CONCLUSIONS: Using these MR-examinations, an improved imaging of early stage arthrotic cartilage defects is possible, and the status of the arthrotic hip cartilage with regard to intertrochanteric osteotomy can also be assessed.

Animals↗
PubMed1989

[Radiological study of the development of the hip joint in children with congenital hip dislocation treated by the Frejka cushion].

The changes in the radiological state of the hip joints between the 2-nd and the 21-st year of age in persons treated for congenital dysplasia of the hip with dislocation have been determined on the basis of the analysis of 3.005 X-razy pictures of 4 or 6 radiological parameters of 916 hip joints in 708 children and the total point evaluation. On comparing the rate of excellent, good and poor results in individual years of life, it has been concluded that marked and quick rebuilding occurs between the 2-nd and the 7-th year of age, and on the other hand, after 10 years of age the radiological state of the hip joint stabilizes.

Adolescent↗