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Biomedical subjects

W H Harris

Publications and source records attributed to W H Harris.

At least 91 records · Page 5Linked to original sources
PubMed1996

Correlation of measured range of hip motion following total hip arthroplasty and responses to a questionnaire.

Twenty-eight patients (with 30 primary and 8 revision total hip arthroplasties) completed a standardized questionnaire containing the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and Harris hip score questions prior to an office visit a minimum of 1 year after surgery. The range of hip motion measured by an orthopaedic surgeon was compared with the responses to questions on stiffness and function as well as with global scores in the WOMAC osteoarthritis index. Patient responses to the questions asking if they could cut their toenails on the operated side and the Harris hip score question asking if they could put on socks and tie a shoe correlated significantly with postoperative hip motion (P < .005). The WOMAC global pain and stiffness scores did not correlate with range of motion. The WOMAC physical function score correlated significantly only with hip flexion (P < .05). Of the WOMAC physical function questions, difficulty bending to pick an object off the floor (P < .05) and getting on and off the toilet (P < .05) correlated with the sum of the range of motion in all planes and weighted Harris hip score range of motion calculation. These data suggest that the points allocated in the Harris hip score for range of motion can be estimated reasonably accurately from questionnaire or phone response to a series of questions on a standardized questionnaire. The question on ability to cut toenails or the Harris hip score question regarding ability to put on socks and tie a shoe correlated with the most individual planes of motion, but several WOMAC physical function questions also correlated with total and weighted range of motion calculations.

Activities of Daily Living↗
PubMed1996

Monitoring the integrity of the cement-metal interface of total joint components in vitro using acoustic emission and ultrasound.

Debonding of the cement-metal interface of cemented femoral components of total hip arthroplasty has been shown from clinical and autopsy material to be a common occurrence. Experimentally, debonding has been shown to increase markedly the strains in the adjacent cement mantle. Studies of autopsy-retrieved specimens demonstrate that debonding of the cement-metal interface is a key initiating event in loosening of cemented femoral components of total hip arthroplasty. However, both the radiographic and autopsy evidence of cement-metal interfacial debonding exist after the fact, that is, after debonding has occurred. The lack of prospective data showing that debonding does indeed occur under physiologic loading and occurs prior to other forms of failure of fixation leaves uncertain the issue of debonding and its role in initiating loosening of cemented femoral components. Knowing when, where, and to what extent the cement-metal interface debonds is critical information in understanding the process of loosening of cemented femoral components. Such information would contribute to improving the durability of stems and improving cementing techniques. In this study, the two nondestructive techniques of acoustic emission and ultrasonic evaluation of the cement-metal interface of cemented femoral stems of total hip arthroplasty were combined to investigate when, where, and to what extent cement-metal debonding occurred in vitro in simulated femurs loaded physiologically in fatigue in simulated single-leg stance. Debonding of the cement-metal interface of a cemented femoral component in this model was both an initiating event and a major mechanism of compromise of the cement-metal interface. Additional acoustic emission signals arose from cracks that developed in the cement.

Acoustics↗
PubMed1996

Differences in stiffness of the interface between a cementless porous implant and cancellous bone in vivo in dogs due to varying amounts of implant motion.

To determine the mechanical properties of the interface between the tissue ingrowth into porous coatings and the implant, porous-coated cylindrical implants were inserted into the distal femur in 20 mature dogs and oscillated in vivo 8 hours per day for 6 weeks at fixed amounts of micromotion (0, 20, 40 and 150 microns). Applied torques and resulting displacements were recorded. The torsional resistance per unit angular displacement (TR/AD), reflecting the stiffness of the bone-porous coating interface, was 0.88 +/- 0.25 N-M/deg immediately after implantation in the 20-micron displacement group. It increased with time after surgery, reaching a maximum of 1.25 +/- 0.60 N-M/deg at 6 weeks. The TR/AD was lower initially (0.77 +/- 0.43 N-M/deg) in the 40-micron group and gradually decreased with time after surgery, reaching a maximum of 0.54 +/- 0.13 N-M/deg at 6 weeks. The TR/AD was even lower (0.24 +/- 0.10 N-M/deg) in the 150-micron group initially and remained the same (0.16 +/- 0.09 N-M/deg) with time after surgery. Histologic evaluation showed bone ingrowth in continuity with the surrounding bone in the 20-micron group consistent with the high stiffness values at sacrifice. In contrast, a mixture of fibrocallus and bone were found at the bone-porous coating interface in the 40-micron group, consistent with the intermediate stiffness values. In contrast, despite the fact that bone was found in the depth of the porous coating in the dogs in the 150-micron group, the low stiffness values were a reflection of fibrous tissue formation at the interface in that group, because of the large motion disrupting bony ingrowth at the bone-porous coating interface. By monitoring the torsional resistance per unit of angular displacement dynamically in vivo, it was possible to evaluate the mechanical properties of the bone-porous coating interface as tissue ingrowth proceeded. Twenty microns of oscillating displacement was compatible with stable bone ingrowth with high interface stiffness, whereas 40 and 150 microns of motion was not.

Animals↗
PubMed1996

Can the western Ontario and McMaster Universities (WOMAC) osteoarthritis index be used to evaluate different hip joints in the same patient?

The Western Ontario and McMaster Universities (WOMAC) osteoarthritis index was originally designed for disease-specific evaluation of patients with lower extremity osteoarthritis (1988), but has not been validated for evaluation of more than one joint at the same time in the same patient. Thirty-three patients with bilateral total hip arthroplasties answered a questionnaire containing both the WOMAC osteoarthritis index and the Harris hip score (HHS) (1969), a joint-specific health status measure that was designed to include evaluation of bilateral hip arthroplasty. Differences in scores between hips were highly correlated for HSS and WOMAC total score (P = .0001), HHS pain and WOMAC pain subscores (P = .0001), and HHS function and WOMAC physical function subscores (P = .0001). WOMAC stiffness and HHS range of motion were not significantly correlated (P = .1308). In 23 patients (70%), both scores graded the hips with the same comparative outcome. When comparative outcomes were different, the average difference was less than 3 points (of 100 possible points). These results demonstrate that patients with bilateral hip arthroplasty can apply the WOMAC osteoarthritis index questions to individual hips at the same time as effectively as the joint-specific HHS questions.

Health Status Indicators↗
PubMed1996

Loci of movement of selected points on the femoral head during normal gait. Three-dimensional computer simulation.

Wear of ultrahigh-molecular-weight polyethylene and the subsequent lytic response to the particulate wear debris are the dominant problems in total joint arthroplasty surgery. Wear testing apparatus can play a vital role in the in vitro evaluation of the many factors involved in wear, such as head size, surface roughness, materials for the head, and new materials for the socket. Wear of ultrahigh-molecular-weight polyethylene may be influenced by the wear path. For the related polymer, high-density polyethylene, the wear path is critical to wear magnitude. What is the actual path taken by a single point (or by multiple representative points) on the femoral head of a total hip arthroplasty as it passes through the gait cycle? The goal of this computer simulation study was to trace the paths of specific points on the femoral head as they moved against the polyethylene cup during a single cycle of normal gait to illustrate the motions occurring at the intraarticular surface of the hip joint. This study also yielded unusual data on the "distance traversed" by these points during a single gait cycle. It was found that there was not one path, but rather there were many, and the paths varied widely in both shape and length depending on the location on the femoral head. Moreover, the differences in excursion and direction at different sites during the loaded phase were great. In addition, distances traveled by different points on the femoral head of any given size varied by a factor greater than 2. Most of the points traced quasielliptical paths. This automatically means that the paths of neighboring points cross each other, creating multidirectional shear forces on the acetabular cup surface which may be important in the localization and extent of wear. The plots of traces of the points derived from this study can serve as benchmarks for the ability of hip simulators to reproduce the actual distances and paths of travel of individual points on the femoral head.

Computer Simulation↗
PubMed1996

Immunohistochemical determination of oestrogen receptor: comparison of different methods of assessment of staining and correlation with clinical outcome of breast cancer patients.

Immunohistochemical staining for oestrogen receptor (ER) has been carried out using antibody ER ID5 on 170 women who received first-line tamoxifen treatment for evaluable metastatic breast cancer. ER status had been determined some years previously, using a ligand-binding cytosol assay. The adequacy of the tissue used for the cytosol assay was always checked by histology on an adjacent block and was deemed to be typical of the tumour overall as was the block used for immunohistochemistry. Six different methods were used to assess the degree of staining and comparisons were made to determine which method gave the most clinically relevant results. Clinical outcome was assessed both in terms of duration of response to tamoxifen determined by log-rank analysis and type of response using the chi-squared test. The ER immunohistochemical assay gave superior results compared with the cytosol assay, with all of the subjective methods of assessment of staining giving statistically significant correlations with clinical outcome. The additional contribution of progesterone receptor (PR) staining with antibody NCL PGR was also studied.

Adult↗
PubMed1996

Revision total hip arthroplasty with use of so-called second-generation cementing techniques for aseptic loosening of the femoral component. A fifteen-year-average follow-up study.

We reviewed the results in a consecutive series of forty-three unselected hips (forty-one patients) after revision of the femoral component, because of aseptic loosening, with use of so-called second-generation cementing techniques. This series was previously reported on after average follow-up intervals of six and 11.7 years; we now report the results after an average duration of follow-up of 15.1 years (range, 14.2 to 17.5 years). None of the eight patients (eight hips) who had died before this review had had a reoperation. Over the course of the study period, repeat revision was done after four (11 per cent) of the thirty-six index procedures that were the first femoral revision and after three of the seven that were a second or third revision. Of the thirty-five hips in the thirty-three surviving patients, seven (20 per cent) had a repeat revision of the femoral component because of aseptic loosening. The average age at the time of the index revision for this group of patients was fifty-one years. This young age has been associated with distinctly poorer results after revision. In two additional hips (two patients), there was radiographic evidence of loosening of the femoral component. Therefore, the rate of loosening of the femoral component was 26 per cent (nine of thirty-five hips) at an average of 15.1 years. These results support the concept that so-called second-generation cementing techniques have decreased the prevalence of aseptic loosening after femoral revision, compared with the shorter-term results that have been reported after revision with use of so-called first-generation cementing techniques.

Adult↗
PubMed1996

Revision of the femoral component of a total hip arthroplasty with the calcar-replacement femoral component. Results after a mean of 10.8 years postoperatively.

Patients who have major loss of bone in the region of the medial aspect of the femoral neck, shortening of the limb, or a high center of the hip joint constitute a special challenge for surgeons performing revision total hip replacements. The use of a so-called calcar-replacement femoral component is one approach to these problems. Of forty-eight hips (forty-four patients) that had been treated consecutively with a total revision arthroplasty with insertion of a calcar-replacement femoral component with cement, thirty-eight hips (thirty-five patients) were followed for a mean of 10.8 years (range, 5.8 to 16.6 years). Ten of the forty-eight hips did not qualify for this study, including nine hips in eight patients who had died before the minimum five-year duration of follow-up and one hip in a patient who had refused follow-up. Of the thirty-eight hips that were followed, seven (18 per cent) had had a repeat revision because of aseptic loosening of the femoral component, one (3 per cent) had been revised again because of lysis around a well fixed femoral component, and an additional four (11 per cent) had a component that was loose according to radiographic criteria. Thus, twenty-six (68 per cent) of the thirty-eight index femoral components were rigidly fixed according to radiographic criteria, and thirty (79 per cent) were still in place. The clinical results were very good for the thirty hips that had not been revised. The mean Harris hip-rating for these patients increased from 50 points preoperatively to 84 points at the most recent follow-up evaluation.

Adult↗
PubMed1996

The Otto Aufranc Award. Skeletal response to well fixed femoral components inserted with and without cement.

Previous studies evaluating femoral remodeling after total hip arthroplasty have used clinical radiographs and dual energy xray absorptiometry. Limitation of these techniques make it impossible to quantify the magnitude of bone loss in terms of cortical thinning and cortical bone area and bone mineral density changes. Femoral cortical bone remodeling after cemented and cementless replacement was quantified and possible determinants of bone remodeling in terms of clinical and radiographic variables were evaluated. Forty-eight anatomic specimen femora from 24 patients with unilateral cemented and cementless hip replacements were analyzed. Cortical thickness, cortical bone area, and bone mineral density was assessed in 4 quadrants at 5 discrete levels. The maximum cortical bone loss by level was at the middle section for the cemented femurs and at the midproximal and middle sections for the cementless femurs. However, if one examines individual quadrants, the proximal medial cortex still represents the specific region of maximal bone loss for both types of implant fixation. The posterior cortex had substantially more bone loss, even in the diaphyseal levels, than had been previously appreciated. A strong correlation was noted between the bone mineral density of the control femur and the percentage decrease of bone mineral density in the remodeled femur. Based on this data, it seems that the less dense the bone is before hip replacement surgery, the greater the extent of bone loss after total hip arthroplasty regardless of the fixation type.

Adult↗
PubMed1996

Hybrid total hip replacement: rationale and intermediate clinical results.

The decade of the 1980s was considered by many hip surgeons to be the decade of cement versus cementless. An alternate approach was introduced in which the acetabular component used was cementless and the femoral component was fixed with cement. This has been called the hybrid total hip replacement. The rationale for this approach is presented and intermediate term results (average, 6.6-year followup) showed that among 65 consecutive standard hybrid total hip replacements in patients who had an average age of 61 years (range, 23-83 years) at the time of surgery, no femoral component was revised for aseptic loosening and no acetabular component was revised for aseptic loosening. Of the 130 components, 3 were removed in 2 patients. One patient had both components removed because of recurrent dislocation and 1 patient had the acetabular component revised because of failure of fixation of the polyethylene liner. The clinical results of this approach were excellent in the intermediate term and may have promise for the long term.

Cementation↗
PubMed1995

Comparison of diametral shrinkage of centrifuged and uncentrifuged Simplex P bone cement.

Reducing the porosity of bone cement substantially strengthens the cement in fatigue. However, concern has been raised that reducing the porosity of the cement would increase the shrinkage of the cement and thus compromise the cement-bone interface. We measured diametral shrinkage of cement mantles prepared with and without centrifugation of the cement. Four cement preparations (centrifuged and uncentrifuged mixed with monomer at either room temperature or 0 degrees C) were used to form cement mantles of four different thicknesses (2, 4, 6, and 8 mm) around a stainless steel rod. We conclude that porosity reduction dramatically increases the fatigue strength of bone cement without substantially changing the diametral dimensions of the polymerized cement when studied in the shape and volume of a cement mantle that would be used for total hip replacement.

Biocompatible Materials↗
PubMed1995

In vitro evaluation of bonding of the cement-metal interface of a total hip femoral component using ultrasound.

Debonding of the cement-metal interface of a cemented femoral component is one mechanism associated with loosening of total hip replacement. An ultrasonic pulse-echo technique was developed to determine, nondestructively, the integrity of the cement-metal interface in vitro. The characteristics of the ultrasonic reflections of bonded and debonded interfaces were obtained by using a physical model that consisted of a flat slab of cement and a flat cobalt alloy plate with known conditions of bonded and debonded interfaces. The same model was used to establish that the ultrasonic technique could distinguish between two surfaces that were in direct opposition but not bonded and those that were actually bonded. This technique then was shown to be useful in nondestructively detecting bonded and debonded cement-metal interfaces of femoral prostheses cemented into fiberglass femurs and femurs from human cadavera.

Bone Cements↗
PubMed1995

Influence of intraoperative femoral fractures and cerclage wiring on bone ingrowth into canine porous-coated femoral components.

Intraoperative femoral fractures occur more frequently with cementless than with cemented components. In this study, the influence of controlled femoral fractures fixed with cerclage wires on rotational stability and bone ingrowth into porous-coated canine femoral components was evaluated. These data were compared with results of previous studies on unrecognized femoral fractures (not stabilized) and on the intact canine femur. Micromotion analysis revealed a significant increase in rotational instability in fractures not stabilized with cerclage wires (P < .05) compared with the intact femur. Experimentally created femoral fractures had a significantly deleterious effect on bone ingrowth even after cerclage wiring. This appears to be caused by a lack of bone ingrowth deep to the fracture and an increase in femoral component micromotion. In clinical practice, femoral fractures occurring during cementless total hip arthroplasty are a serious problem, and use of a cemented prosthesis is recommended if rotational stability of the stem cannot be ensured.

Animals↗
PubMed1995

Increasing prevalence of femoral lysis in cementless total hip arthroplasty.

A follow-up study was made of 94 primary total hip arthroplasties in 86 patients with a Harris-Galante (Zimmer, Warsaw, IN) porous-coated femoral component implant to determine the change in prevalence of femoral lysis and its clinical significance. At a mean follow-up period of 53 months (range, 16-86 months), femoral lysis was present in 31% of the femurs. In the first report of this condition, the incidence was 3%. The mean patient age was 54 years (range, 30-69 years). The most common diagnosis was osteoarthritis (62 hips). Of the 29 hips with femoral lysis, 11 were graded as extensive. Of the 14 hips in which the femoral component was defined as loose, 12 had femoral osteolysis; however, the mean Harris hip score among those with lysis was not reduced in those with femoral osteolysis (88 compared with 90 the entire group). Pelvic osteolysis, in contrast, was present in only one hip, around a screw. In this series, femoral lysis was a major complication, whether the femoral component was stable or not, and the prevalence of lysis increased sharply over time.

Adult↗
PubMed1995

Effect of improved cementing techniques on the longevity of fixation in revision cemented femoral arthroplasties. Average 8.8-year follow-up period.

Forty-six revision cemented femoral arthroplasties in which second-generation cementing techniques were used have been reviewed. After an average follow-up period of 8.8 years, 91% of the femoral components remained in place and 87% remained well fixed. Only 7% were rerevised for aseptic loosening. These results demonstrate a marked improvement over those of first-generation cementing techniques.

Adolescent↗