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Biomedical subjects

P M Rozing

Publications and source records attributed to P M Rozing.

At least 19 recordsLinked to original sources
PubMed1996

Influence of glenohumeral prosthesis geometry and placement on shoulder muscle forces.

The authors studied the influence of a changed geometry of the glenohumeral joint on the function of the muscles with the use of a shoulder prosthesis with an anatomic design. The changed geometry is characterized by 4 parameters: orientation of the glenoid, radius of the humeral head, position of the glenohumeral joint's geometric center in relation to the scapula, and position of the glenohumeral joint's geometric center in relation to the humeral shaft. The effect of changes in these 4 parameters was investigated with an inverse dynamic 3-dimensional musculoskeletal model of the shoulder. This was done at 60 degrees and 90 degrees of abduction and flexion. Gravity was the only external force on the arm. The magnitudes of the introduced changes are assumed to be a realistic representation of a changed geometry due to the implantation of a prosthesis. In most situations, the effect of a change in the 4 parameters on the exerted muscle force was small compared with the maximum force of a muscle. However, in relation to the initial reference force in a muscle, changes with an average of 50% occurred. Changes in the geometric center's position relative to the humerus are especially important, because they are closely related to the retroversion angle and can cause changes in force of up to 300%.

Biomechanical Phenomena↗
PubMed1996

Assessment of shoulder function in rheumatoid arthritis.

OBJECTIVE: (1) To develop a simple outcome measure of shoulder function in rheumatoid arthritis (RA), the Shoulder Function Assessment (SFA) Scale; (2) to compare the properties of this scale with those of 2 existing measures of shoulder function, the Constant Scale and the Hospital for Special Surgery (HSS) Scale. METHODS: Fifty consecutive patients with RA participated in an inpatient multidisciplinary treatment program. The SFA Scale was constructed by selecting items considered simple to assess and relevant to shoulder function by a team consisting of a rheumatologist, an orthopedic surgeon, a physical therapist, and an occupational therapist. To examine the intra and interobserver reliability in 25 patients the SFA Scale, the Constant, and the HSS Scale were assessed twice by examiner CHME, in the other 25 patients once by examiner CHME, and once by examiner EMV. The validity of all 3 scales was determined by calculating the correlation with (1) the observed shoulder function, (2) the patient's opinion of shoulder function, and (3) shoulder joint deformity. A receiver operating characteristic curve was constructed to determine the accuracy of all scales to discriminate between differences in the shoulder function of the "best" and "worst" shoulder as reported by the patient. RESULTS: The validity and the reliability of the SFA Scale were equivalent to or better than the validity and reliability of the Constant and the HSS scale. The discriminative ability of the SFA Scale was superior to both other scales. CONCLUSION: The SFA Scale is a reliable, valid, and accurate measure of shoulder function in patients with RA that can be completed within 3 minutes.

Adult↗
PubMed1995

The intramedullary hydraulic pressure tolerance of the human femur.

A new range of clinically used, biodegradable, bone-bonding copolymers has hydrogel properties. With intramedullary press fit, these polymers generate considerable pressure through swelling caused by water absorption. In total hip arthroplasty, high intramedullary pressures can be attained by insertion of the prosthesis into femora by using methylmethacrylate cement and a cement plug. Because the effects of such intramedullary pressures are not fully known, 10-cm-long segments of the proximal diaphysis of fresh femoral bones from 22 human cadavers were tested for their intramedullary pressure resistance. The intramedullary pressure resistance, calculated burst forces, and stress on the bone were correlated to age, gender, bone mineral content per unit length, and bone mineral density. In most bone segments, a burst fracture occurred just opposite the linea aspera. The hydraulic bursting pressures ranged from 2.3 to 13.4 MPa (age adjusted gender effect [male-female], 2.2 MPa [p = 0.05]). The forces at fracture were calculated to be between 265 and 1361 N (regression coefficient: 247/unit bone mineral content per unit length). The tangential stress appeared to be between 7.54 and 27.54 MPa (regression coefficient: 11.6/unit bone mineral density; bone mineral density adjusted gender difference [male-female], 4.5 MPa [p < 0.05]). Biochemical examination of the bones did not show any abnormalities. The results of this study show that the human femora can resist mechanically an intramedullary pressure of at least 2 MPa. From a mechanical point of view, intramedullary pressures generated by swelling polymers should remain below 2 MPa for safe use.

Aged↗
PubMed1993

A histological and histomorphometrical investigation of fluorapatite, magnesiumwhitlockite, and hydroxylapatite plasma-sprayed coatings in goats.

Plasma-sprayed ceramic coatings of fluorapatite (FA), magnesiumwhitlockite (MW), and hydroxylapatite (HA), and noncoated Ti-6Al-4V alloy (Ti) implants were evaluated histologically and histomorphometrically in a goat animal study. Cylindrical Ti-6Al-4V plugs were plasma-spray-coated with FA, MW, and HA. Noncoated, grit-blasted Ti plugs served as controls. The plugs were implanted into the right femur and left humerus of 20 adult goats. The results were evaluated using descriptive histology and histomorphometry. The histomorphometry consisted of measurements of bone apposition and coating thickness. The results demonstrated that FA showed a high amount of bone apposition without signs of degradation or dissolution. MW showed considerable reduction in thickness and at 12 weeks an adverse tissue reaction. However, at 25 weeks the amount of bone apposition was significantly increased compared with the 12-week implants. HA revealed considerable and progressive reduction in thickness and at 25 weeks a lower amount of bone apposition than FA and MW. At 12 weeks the Ti implants did reveal bone apposition, although frequently localized fibrous tissue was visible. At 25 weeks the Ti implants did not differ in bone apposition from the HA implants. Further studies are necessary on the effect of degradation or dissolution of HA on the compatibility with bone.

Alloys↗
PubMed1993

Hydroxylapatite/poly(L-lactide) composites: an animal study on push-out strengths and interface histology.

In the development of new materials for resorbable systems for bone fixation and replacement, composites of hydroxylapatite and poly (L-lactide) (HA/PLLA) were tested. In a transcortical implantation model in goats the interactions at the bone-implant interface were studied with post-operative intervals up to 1 year. Push-out testing of the implants indicated that PLLA reinforced with 50 wt% hydroxylapatite or PLLA plasma-sprayed with a hydroxylapatite coating of 50 microns thickness increases interfacial shear strength at 3 months of implantation when compared to unfilled poly(L-lactide) (P < .01). Scanning electron microscopy showed that the failure mode was predominantly at the coating-implant interface. Implantation periods longer than 3 months did not result in a significant increase in push-out strength because of the resorbing PLLA matrix. In support of the above findings there was histological evidence, on a light microscopical level, of increased bone contact at the interface for the composites, HA incorporated in or coated on PLLA, compared to unfilled poly(L-lactide).

Animals↗
PubMed1993

In vitro study on the integrity of a hydroxylapatite coating when challenged with staphylococci.

An in vitro study was performed to evaluate the effect of Staphylococcus aureus and Staphylococcus epidermidis on the integrity of a hydroxylapatite coating. The coating plasma-sprayed on poly(L-lactide), showed dissolution during a 24 h incubation period. This was indicated by an increase in pH and calcium release in the buffer solution. After 4 h of incubation, calcium levels decreased due to the precipitation of calcium phosphate complexes on the coating. The bacteria digested or dissolved the coating, creating irregularly shaped holes. Although the integrity of the hydroxylapatite coating was focally damaged within 2-4 h of incubation with staphylococci, the extent of the damage was only marginal. Due to the formation of a layer of CaP precipitates though, bacteria could not be counted accurately after 4-8 h of incubation. This model could reveal part of the failure mechanism of infected hydroxylapatite coated implants.

Calcium↗
PubMed1993

The topographical anatomy of the brachial plexus.

The anatomy of the shoulder region is discussed focusing on the course of the brachial plexus. Magnetic resonance imaging enables one to visualize the topographical anatomy of this area.

Brachial Plexus↗
PubMed1993

Tissue response to the failed Gerard double-cup. Histologic analysis of 40 uncemented hip arthroplasties.

Femoral head remnants, joint capsules and acetabular membranes were retrieved at revision of 40 failed uncemented, Gerard double-cup hip arthroplasties. All femoral heads were covered with a fibrous membrane containing polyethylene and metal particles, macrophages, and giant cells. The same histopathologic features were found in the joint capsules and acetabular membranes. There was a relationship between the amount of polyethylene particles in the fibrous membrane of the femoral head and the presence of osteonecrosis. Resorption of necrotic bone contributed to failure of the arthroplasty, aided by granulomatous reactions to the wear particles that appeared to induce osteolysis. The overall findings indicate that the severity of the foreign body reaction in periprosthetic tissues is related to the amount of wear particles. Future designs of resurfacing hip arthroplasties should be focused on wear-resistant material combinations.

Biocompatible Materials↗
PubMed1993

Frejka pillow and Becker device for congenital dislocation of the hip. Prospective 6-year study of 104 late-diagnosed cases.

During the period 1974-1986, 107 consecutive 1-9 month-old children with late-diagnosed congenital dislocation of the hip (CDH) were treated with a Frejka pillow primarily, followed by a Becker device. Treatment was initially successful in 96 cases with 2 not reduced, 4 failed stabilization, 4 persisting dysplasia, and 1 avascular necrosis. No correlation was found between age at the time of diagnosis or the severity of the dislocation and the duration or the result of treatment. In those initially successful, 14 percent had slight dysplasia 6 months later. The last follow-up, at the mean age of 7 years, excluding the 11 children needing supplementary treatment, showed that 84 percent had normal hips on radiography, based on measurements of the acetabular angles and the center-edge angles. The clinical findings were normal.

Female↗
PubMed1993

The uncemented Gerard bipolar double-cup arthroplasty of the hip. A five- to 11-year follow-up study.

Between 1978 and 1984, 183 hips in 154 patients with the uncemented Gerard double-cup arthroplasty were resurfaced. The clinical and radiographic results of the 106 original arthroplasties were reviewed after a median follow-up period of 98 months. Although many of these patients had clinically improved immediately, the Harris Hip score decreased significantly in most hips in subsequent years. No correlation was found between the clinical score and radiographic complications. Major revision surgery with removal of the double cup was performed in 54 of 183 patients, making the cumulative success rate after 132 months only 48%. Survival was significantly greater in patients younger than 50 years of age and in patients with a low body weight (Quetelet index less than 25). This high failure rate eliminates the Gerard double-cup arthroplasty, except possibly for the patient with a destructive inflammatory arthropathy for whom there are no other surgical alternatives.

Adult↗
PubMed1992

[Good 10-year results following cemented total knee arthroplasty].

The results of primary total knee arthroplasty in patients with a follow-up of 4-10 years are presented. The study population consisted of osteoarthritis as well as rheumatoid arthritis patients. Both groups were analyzed separately for postoperative pain reduction at rest and during activity, as well as for improvement of some daily activities (walking distance, stair climbing). Pain reduction at rest and during activity was maintained during the follow-up period of 4-10 years. The walking distance and the ability to climb stairs improved during the first few postoperative years, but declined in the later postoperative years. Survival curve analysis of the total knee arthroplasty showed good results for osteoarthritis as well as rheumatoid arthritis (estimated probability of survival of the prosthesis at 10 years' follow-up was 94%).

Aged↗
PubMed1992

A finite element analysis of the push-out test: influence of test conditions.

The commonly used method for quantitative evaluation of the strength of a bone-implant interface is the push-out test. In order to give an impulse to standardization and to gain more insight in the biomechanics of the push-out test, a finite element analysis of this test was performed. This study focused on the influence of test conditions on the push-out results. The influence of the following four parameters on the interface stress distribution was tested: (a) clearance of the hole in the support jig, (b) Young's modulus of the implant; (c) cortical thickness; and (d) implant diameter. The distance between the implant and the support jig turned out to be very critical for the occurrence of peak stresses in the interface. Variations of the Young's modulus of the implants resulted in a wide range of interface shear stresses. Variation of the cortical thickness showed a reciprocal relationship between cortical thickness and interface shear stress. However, the interface stress distribution remained uniform under the specific test circumstances. These findings also hold for variations in implant diameter. The present investigation shows that the clearance of the hole in the support jig, and the Young's modulus of the implant are parameters which most strongly influence the interface stress distribution. The clearance of the hole in the support jig is the most critical parameter, but also the parameter that can be controlled most easily. Lack of standardization with regard to these parameters can lead to uninterpretable test results. It is recommended that the clearance of the hole in the support jig is at least 0.7 mm and that push-out results are only compared with each other when materials with similar Young's modulus are concerned.

Animals↗
PubMed1992

A surgical approach in total shoulder arthroplasty.

The long deltopectoral approach promoted by Neer is the standard for performing a total shoulder arthroplasty. However, this exposure is inadequate for preparation and bone grafting of the glenoid cavity or repairing an associated large rotator cuff tear. In the anatomy laboratory we looked for an alternative approach to the glenohumeral joint which would accommodate these difficulties. Afterwards we used this approach in 7 of 13 patients in whom a Biomet Bio-modular shoulder arthroplasty was planned. The study is prospective with a 1-year follow-up of 12 cases.

Aged↗
PubMed1992

Diffusion of cloxacillin into synovial tissue.

After a 30 min i.v. infusion of 1 g cloxacillin, the concentrations of this antibiotic were measured in plasma and synovial tissue samples from 11 patients undergoing total hip replacement. Assuming passive distribution between plasma and tissue the rate constants of distribution were estimated. The mean half-life of distribution was 22 min. The concentration of free drug in synovial tissue was estimated to be 77% of the total tissue concentration. The maximum tissue drug concentration after an i.v. bolus dose is predicted to occur at about 37 min.

Aged↗
PubMed1992

Survivorship analysis in total condylar knee arthroplasty. A statistical review.

Survivorship analysis, which is often encountered in the medical literature, is used to calculate the probability of a certain event, such as failure of a prosthesis, as a function of the time elapsed since an operation. Possible pitfalls in the use of this method are related to the size of the population of patients and the definition of how the outcome is measured. We studied the outcomes of 204 total knee arthroplasties in 165 patients, using six different end-points, in order to illustrate these problems. Survivorship estimates that are cited without confidence intervals have little clinical value.

Adult↗
PubMed1991

A mechanical investigation of fluorapatite, magnesiumwhitlockite, and hydroxylapatite plasma-sprayed coatings in goats.

Ceramic coatings of fluorapatite (FA), magnesiumwhitlockite (MW), and hydroxylapatite (HA), and noncoated Ti-6Al-4V alloy (Ti) implants were evaluated before and after implantation in an animal study. Cylindrical plugs were coated by plasma-spraying with FA, MW, and HA. X-ray-diffraction patterns showed for FA and HA a crystalline and for MW an amorphous-crystalline coating structure. The plugs were implanted into the right femora and left humeri of 16 adult goats. Follow-up periods were 12 and 25 weeks. The in vivo results were evaluated using push-out tests and scanning electron microscopy. There were significant differences in push-out strengths between femur and humerus. The FA and HA implants showed significantly higher push-out strengths than the MW and Ti alloy implants, especially for the 12 week follow-up period. Furthermore, at 12 weeks, MW showed significantly lower push-out strengths than Ti alloy. SEM-investigation of the interfaces revealed that FA did not degrade while both MW and HA showed extensive degradation at 12 and 25 weeks. In addition, the interface after push-out testing showed for the MW, HA, and Ti alloy implants to be fractured at the implant-tissue interface and for the FA to be fractured at the coating-titanium interface.

Animals↗
PubMed1991

Uncemented bipolar double-cup arthroplasty of the hip in inflammatory arthropathy.

From 1979 to 1986, 42 uncemented surface arthroplasties were performed in 27 patients with an inflammatory arthropathy of the hip: median age at operation 40 years (range 19-65 ys), median follow-up period 73 months (range 36-120 mo). After 36 months, in 26 of 42 hips, the mean Harris Hip Score was excellent or good (mean 89, range 80-100). In 14 cases, the mean score was fair (76, range 70-79). Overall, those hips with the longest followup period (60-120 m) gradually improved over the years. No correlation was found between the clinical score and radiologic complications such as varus tilting of the femoral component, acetabular protrusion of the cup, or heterotopic ossification. Conversion to a conventional total hip arthroplasty was required in four patients. One patient required a total hip arthroplasty 86 months after the initial operation because of a femoral neck fracture. In two other patients, revision was performed after 60 and 32 months respectively because of a preexistent osteonecrosis and a severe foreign body response to polyethylene debris. Both patients had a varus tilting of the femoral component. In the fourth patient, in whom revision surgery was necessary 28 months after surface replacement there was no explanation for the varus shift of the femoral component. Regarding those problems that can appear after conventional total hip replacement in inflammatory arthropathy, we conclude that the uncemented surface replacement of the hip can be a reasonable alternative.

Adult↗