Biomedical subjects

J M Martell

Publications and source records attributed to J M Martell.

10 recordsLinked to original sources

PubMed2006

Cementless acetabular reconstruction and structural bone-grafting in dysplastic hips.

BACKGROUND: Studies of acetabular reconstruction with use of cement and bulk bone graft have demonstrated increasing rates of cup failure in patients with dysplastic hips seven years after total hip arthroplasty. Comparable data on the long-term results of bulk bone-grafting done in conjunction with cementless implants are limited. The aim of this study was to review the clinical and radiographic results of autologous bulk bone-grafting in conjunction with a cementless cup. METHODS: From 1987 to 1992, forty-seven patients (forty women and seven men, with an average age of 50.4 years) who had developmental dysplasia of the hip underwent fifty-six total hip arthroplasties and received a structural graft in combination with a cementless Harris-Galante type-I cup. All patients were followed prospectively. In fifty-five hips, implant migration was measured with single-image radiographic analysis. RESULTS: After an average duration (and standard deviation) of 10.2 +/- 2.9 years, three patients (four hips) had died. In the surviving patients, four implants had been revised and two had radiographic evidence of loosening. With use of revision and loosening as end points, the eleven-year survival rates were 91.6% and 88.9%, respectively. Of the fifty implants that had no loosening, fourteen had measurable cup migration, thirty-five had no migration, and one implant could not be measured. All migrations but one were progressive. With loosening used as the end point, the survival rate at eleven years was 100% for the implants with no migration; however, the survival rate for the cups that had migrated was 69.3% (p = 0.0012). CONCLUSIONS: The eleven-year survival rate for the spherical press-fit cups in combination with bulk bone-grafting is satisfactory, given the complexity of these reconstructions. However, the difference between the survival of the implants that had migrated and those that had not was significant. We expect that the thirteen implants with progressive acetabular migration at the time of the latest follow-up are at risk for loosening, which will increase the revision rate for this series in the coming years.

Acetabulum↗

PubMed2005

In vivo comparative wear study of traditional and highly cross-linked polyethylene in total hip arthroplasty.

In this study, we compare the in vivo wear performance of electron beam-irradiated, postirradiation-melted, highly cross-linked polyethylene (HXLPE) and traditional UHMWPE via the Martell method. Seventy hips with HXLPE performed at the Massachusetts General Hospital had 138 radiograph pairs for wear analysis and a 31.2-month average follow-up (range, 24-44 months). An age-matched, sex-matched, and body mass index-matched subgroup of 111 hips with 214 acceptable radiograph pairs and a 4-year follow-up from our previously published study on traditional polyethylene performed at Rush-Presbyterian-St. Luke's Medical Center served as a control group. Martell wear analysis was performed for each group. Overall and steady-state wear rates were compared via a specialized t test. The steady-state wear in the HXLPE arm was observed after 2.0 years, was 0.007 mm/y, and was significantly less than the steady-state wear in the traditional arm (0.174 mm/y) (P = .003). Highly cross-linked polyethylene penetration rate was not affected by sex, age, activity, or body mass index by Mann-Whitney analysis.

Arthroplasty, Replacement, Hip↗

PubMed2000

Normalized BMD as a predictor of bone strength.

RATIONALE AND OBJECTIVES: In the noninvasive evaluation of bone quality, bone mineral density (BMD) has been shown to be the single most important predictor of bone strength and osteoporosis-related fracture. Among the methods of measuring BMD, dual x-ray absorptiometry (DXA) has widespread acceptance due to its low radiation, low cost, and high precision. However, DXA measures area BMD instead of true volumetric density; thus, a larger bone will tend to have a high BMD than will a smaller bone. Therefore, the comparison of BMDs of bones of different sizes can be misleading. In this study, the authors tried to compensate for the size effect by normalizing the area BMD with bone size as measured from a standard pelvic radiograph. MATERIALS AND METHODS: The overall method for calculation of normalized BMD included conventional area-based BMD from DXA and the extraction of geometric measures from pelvic radiographs. The database for analysis included 34 femoral neck specimens. Regression analysis was performed between the normalized volumetric BMD, measured from femoral neck region, and the mechanical properties obtained from trabecular bone cubes machined from the same region. RESULTS: After normalization of the area BMD, the coefficient of determination increased from 0.30 to 0.43 for the Young modulus and from 0.27 to 0.37 for bone compressive strength. CONCLUSION: A noninvasive method of normalizing BMD can improve the prediction of bone mechanical properties and has potential in monitoring changes in growing skeletons and in the clinical evaluation of bone quality.

Absorptiometry, Photon↗

PubMed2000

The effect of joint loading on acetabular wear measurement in total hip arthroplasty.

All radiographic calculations of acetabular wear assume concentric reduction of the prosthetic articulation. To date, no studies have shown that the femoral head is fully reduced on standard radiographs, and we have seen cases on early postoperative radiographs in which this assumption is not met. Using our computerized radiographic technique, 78 paired anteroposterior pelvic radiographs in 46 patients at a mean of 14 months after surgery (range, 1-92 months) were evaluated with and without joint loading. Displacement with loading was analyzed against time since surgery, a surrogate for acetabular wear. Regression analysis found a statistically significant increase in femoral head displacement after loading with longer duration of follow-up, but the rate of this increase was small (0.027 mm/y). This difference affects calculated wear values by <15%. We conclude that in a low-wear cohort, joint loading does not affect radiographic calculations of acetabular polyethylene wear in a clinically important way.

Acetabulum↗

PubMed2000

Computerized analysis of radiographic bone patterns: effect of imaging conditions on performance.

We are developing computerized methods for characterizing the bone texture pattern from digitized skeletal radiographs. For this method to be useful clinically, it must be able to distinguish between weak and strong bone under the range of exposure conditions potentially encountered in the clinical setting. In this study, we examined the effect of exposure conditions on Fourier-based texture features. Thirty-four femoral specimens from total hip arthroplasties were radiographed multiple times under different exposure conditions. The specimens underwent mechanical strength testing from which load to failure values were obtained. The performance of the texture features were investigated in the task of distinguishing between strong and weak bone as characterized by the load to failure values. The texture features showed no dependence upon focal spot size of the x-ray tube or magnification. The texture features did show a dependence with relative exposure, peak kilovoltage, and amount of scattering material.

Biophysical Phenomena↗

PubMed1999

Characterization of bone quality using computer-extracted radiographic features.

Both bone mineral density (BMD) and trabecular structure are important determinates of bone mechanical properties. However, neither BMD or trabecular structural features can completely explain the variations in bone mechanical properties. In this study, we combine BMD and bone structural features to characterize bone mechanical behavior. Radiographs were obtained from 34 femoral neck specimens excised during total hip arthroplasties. Each neck radiograph was digitized and a region of interest (ROI) was selected from the medial side of the femoral neck. Textural features, the global Minkoswski dimension and trabecular orientation, were extracted from each ROI image using Minkowski dimension analysis. The BMD of each specimen was measured using dual-energy x-ray absorptiometry (DXA) and subsequently normalized by bone size as measured from a standard pelvis radiograph. Mechanical testing was performed on the trabecular bone cubes machined from each femoral neck to yield bone mechanical properties. Multiple regression was performed to select the best features to predict bone mechanical properties. The results suggest that, using multiple predictors including normalized BMD structural features, and patient age, the coefficients of determination (R2) improved over the use of BMD alone. For bone strength, the R2 was improved from 0.24 using conventional BMD to 0.48 using a four-predictor model. Similar results were obtained in the prediction of Young's modulus, i.e., the R2 was improved from 0.25 to 0.55 in going from the model using conventional BMD to a four-predictor model. This study demonstrates the contributions of normalized BMD, structural features, and age to bone mechanical properties, and suggests a potential method for the noninvasive evaluation of bone mechanical properties.

Absorptiometry, Photon↗

PubMed1999

Computerized radiographic texture measures for characterizing bone strength: a simulated clinical setup using femoral neck specimens.

We are investigating computerized methods to ultimately characterize bone trabecular pattern from clinical skeletal radiographs. In this paper, we present a "phantom" for potential use in the development and evaluation of computerized methods for characterizing radiographic trabecular patterns and ultimately bone strength. Femoral neck specimens were excised during total hip arthroplasties from subjects exhibiting a range of diseases. To mimic the femoral neck in vivo, a "simulated clinical" setup was implemented in which specimens were exposed under conditions that yielded radiographs similar in appearance to standard pelvis radiographs. Fourier-based and fractal-based texture measures were used in the computer analysis; including RMS variation, first moment of the power spectrum, angular-dependent forms of these measures, and fractal dimension. The texture measures obtained from the "simulated clinical" specimen films correlated modestly with those from direct exposure "verification" films of the specimens (r= 0.59-0.69; p<0.0001). From our study, we conclude that the femoral neck specimen "phantoms" may be useful in the development and evaluation of computerized methods for analyzing bone trabecular patterns from skeletal radiographs. The use of a phantom that simulates the clinical radiographic examination allows for repeat exposures without the concern of excessive radiation exposure to a patient.

Adult↗

PubMed1997

Determination of polyethylene wear in total hip replacements with use of digital radiographs.

UNLABELLED: We describe a computer-assisted vector wear technique for the determination of polyethylene wear on digital radiographs. Twenty-five hips that had had a total hip arthroplasty were used to evaluate the repeatability and performance of three radiographic techniques to measure wear of the acetabular polyethylene liner: the manual technique with use of calipers described by Livermore et al., the same technique with use of a digitizing tablet, and our new technique of computer-assisted vector wear analysis. We found our new technique to be at least ten times more repeatable than the technique with use of either calipers or a digitizing tablet. Fourteen of the polyethylene liners were retrieved at autopsy, and the actual measurements of wear of those liners were compared with the measurements that had been obtained with the three radiographic techniques of wear analysis. Computer-assisted vector wear analysis outperformed the manual techniques of Livermore et al. When compared with the data obtained from the specimens retrieved at autopsy, the measurement of wear determined with the computer-assisted technique differed by an average of 0.08 millimeter, whereas the measurements obtained with use of calipers and use of a digitizing tablet differed by 0.26 and 0.25 millimeter, respectively. The performance of computer-assisted vector wear analysis in the clinical setting was evaluated with use of controls with known amounts of wear. These were mounted in pelvic phantoms, and radiographs were made with use of a setup that simulated the clinical setting. Analysis of nine controls with 2.0 millimeters of wear yielded an average measurement of wear (and a standard deviation) of 1.99 +/- 0.21 millimeters. CLINICAL RELEVANCE: Computer-assisted vector wear analysis demonstrated superior repeatability and accuracy compared with current techniques of manual analysis. Improved repeatability and accuracy in the determination of polyethylene wear should facilitate the investigation of factors related to the prosthesis and to the patient that affect the rates of wear.

Acetabulum↗

PubMed1995

Total hip replacement with insertion of an acetabular component without cement and a femoral component with cement. Four to seven-year results.

One hundred and fifty-three so-called hybrid total hip replacements were performed in 142 patients from 1985 to 1987 at Rush-Presbyterian-St. Luke's Medical Center. A hemispherical porous-coated acetabular component was inserted without cement and was fixed with screws, and a femoral stem was inserted with the use of so-called third-generation cementing techniques. The average age of the patients at the time of the operation was sixty-seven years (range, thirty-nine to eighty-five years). The average preoperative Harris hip score was 46 points (range, 9 to 73 points). One hundred and eleven patients (120 hips) were available for clinical review; 100 of these patients (109 hips) had a complete set of radiographs available. The average Harris hip score was 86 points (range, 29 to 100 points) at the time of follow-up (average duration, sixty-two months; range, forty-eight to eighty-five months). There was progressive migration of one cup (1 per cent); another cup migrated one centimeter in the first two years after the operation, with no additional migration evident after that time. The remaining acetabular components were stable. Two femoral components (2 per cent) were determined to be definitely loose. The remaining femoral components were stable. This population of patients had a good result after so-called hybrid total hip replacement with insertion of a porous-coated acetabular component without cement and a femoral component with cement for the reconstruction of a painful hip.

Adult↗

PubMed1993

Primary total hip reconstruction with a titanium fiber-coated prosthesis inserted without cement.

A prospective study was done of the intermediate-term clinical and radiographic results of 121 total hip arthroplasties in which a Harris-Galante porous titanium-fiber-coated prosthesis was inserted without cement in 110 patients. The average age at the time of the operation was forty-nine years (range, twenty to seventy years). The average duration of follow-up was sixty-seven months (range, fifty-five to seventy-nine months). The average preoperative Harris hip score was 55 points, and the average postoperative score was 93 points. One acetabular component was revised due to recurrent dislocation. Eleven femoral implants were unstable, and of these, four were revised. Cortical erosion was present around the distal part of the femoral stem in nine patients (8 per cent) who had stable implants, and one of these femoral implants was revised because the erosion was extensive. Survivorship analysis at five years revealed a 97 per cent chance of survival (95 per cent confidence limit, 0.937 to 1.0) of the Harris-Galante femoral-stem implant inserted without cement.

Acetabulum↗