Evaluation of bone ingrowth in proximally and extensively porous-coated anatomic medullary locking prostheses retrieved at autopsy.

Three proximally (40 per cent) and five extensively (80 per cent) porous-coated anatomic medullary locking femoral components were retrieved from seven cadavera at autopsy. Each component (with the surrounding, intact femur), was sectioned transversely at one-centimeter intervals. Backscattered scanning electron microscopy was used to evaluate circumferentially the interface between the bone and the porous surface of each section. Bone ingrowth was considered to be present within a field when bone was in contact with the outermost layer of the sintered beads, it was detected within the porous space, and it had penetrated the porous space to a depth of at least one bead diameter. All eight components had some bone growth into the porous space. A mean of 35 per cent of the surface of the implants had bone ingrowth. In the areas where bone was present, 67 per cent of the available porous space on the extensively coated stems and 74 per cent on the proximally coated stems contained bone. With both types of implants, the greatest amount of compact bone ingrowth was found at the level where the porous coating ended. Transverse sections obtained at this level frequently demonstrated that bone ingrowth had occurred circumferentially and that the ingrowth was continuous with and an integral part of the femoral cortex. These direct connections to the cortex could be predicted from the appearance of the radiographs. In the most proximal transverse sections of both types of implants, bone was most frequently connected to the medial side and corners of the implant.(ABSTRACT TRUNCATED AT 250 WORDS)

Cortical bone density of the proximal femur following cementless total hip arthroplasty.

A quantitative analysis of cortical bone remodeling was performed using calibrated videodensitometry. Six femoral specimens were obtained at autopsy from 3 patients treated with unilateral porous coated femoral components in situ > 6 years. Transverse thick sections of the remodeled and normal femora were obtained. Slab radiographs of the sections were analyzed using computer assisted videodensitometry. Detailed density plots of each section were constructed and the average density in defined quadrants was recorded. The density plots were also used to measure the cortical bone area present on each section. Two cases showed a gradient of resorptive remodeling change with the greatest density loss noted medially at the proximal levels (33% and 36%). The 3rd case had porotic cortical bone in the normal femur and demonstrated a different remodeling pattern, with the greatest average resorptive change (57%) measured in the midstem region. Changes in cortical area were variable: 1 showed cortical thickening in the midstem region; another had decreased cortical area in the entire region adjacent to the porous coating; and the 3rd had decreased cortical area proximally, with minimal changes noted in the distal levels. The volumetric densities measured by videodensitometry were compared with area densities measured with dual energy xray absorptiometry. There was a strong linear correlation between the 2 methods (r2 = 0.80).

Porous-coated total hip replacement.

Fifteen years of clinical experience with porous-coated prostheses demonstrated the durability of this type of fixation. This experience was documented by clinical follow-up study of the 393 cases treated by the senior author before 1985. Only six of these femoral components have been revised: three for loosening, two for stem breakage, and one for infection. Thus, the revision rate for the porous-coated stems was 1.5%. Porous-coated acetabular components were used in 227 of the arthroplasties. Five of these porous-coated cups have been revised: four for malposition leading to dislocation and one for late loosening secondary to osteolysis. Thus, the revision rate for these porous-coated acetabular components was 2.2%. Twenty bipolar and 146 cemented acetabular components were used in the remaining 166 cases treated before 1985. Eleven (7.5%) of the cemented acetabular components were revised. Revisions of the porous-coated components were rare in the first ten postoperative years. The clinical data were supplemented with analysis of postmortem specimens from 15 patients. Mechanical testing of the femoral specimens showed the relative micromotion at the porous surface to be exceptionally small (less than 40 microns). Seven of these postmortem retrievals involved cases with unilateral arthroplasties. In these cases, the contralateral normal femur also was removed, and a prosthesis identical to that in the in vivo implanted side was inserted to simulate the immediate postoperative condition. Dual-energy X-ray absorptiometry (DEXA) of the seven paired femora demonstrated that bone remodeling can be expected to produce a 5%-52% loss of periprosthetic bone mineral content, with the greatest loss occurring in the more osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Roentgenographic densitometry of bone adjacent to a femoral prosthesis.

A digital imaging method was developed to quantitate the stress-related changes in roentgenographic bone density after total hip arthroplasty. A technique termed "histogram-directed equalization" was used to compensate for differences in postimaging data caused by the effects of variable quality obtained from ten patients. Quantitative change due to variation in delivered energy was decreased by 7% for roentgenograms obtained with a 2 kVp variation and 31% for roentgenograms obtained with a 4 kVp variation. The method allowed the authors to accurately describe the changes observed on annual postoperative roentgenograms obtained over the past decade. The utility of the method was demonstrated in 15 of the senior author's long-term cases treated with fully porous-coated implants. These cases were divided into two groups based on the diameter of the prosthetic stem implanted in each case. Five patients were grouped with small-diameter stems and ten with large-diameter stems. Both groups showed substantial decrease in roentgenographic bone density (from 11% to 28%) in the medial and lateral proximal regions. The large-diameter group had an overall larger decrease in roentgenographic bone density at two and five years. Roentgenographic bone remodeling changes were most pronounced in the first two years. Changes between two and five years progressed at a slower rate. The results also confirmed the predicted effect of stem diameter on bone remodeling patterns.

Quantification of implant micromotion, strain shielding, and bone resorption with porous-coated anatomic medullary locking femoral prostheses.

Fourteen femora containing porous-coated anatomic medullary locking (AML) femoral prostheses were retrieved from 12 patients at autopsy. Clinical roentgenograms in 13 femora showed bone remodeling changes, indicating that the implants were fixed by osseointegration. Under simulated physiologic loading, micromotion between the implant and the bone was measured using electrical displacement transducers connected to the implant and to the adjacent cortex. The micromotion between the implants at the areas of porous coating and the adjacent cortex in the one case of failed bone ingrowth measured 150 microns. Maximum relative motion between the cortex and the implant in the areas of porous coating for the 13 cases showing signs of bone ingrowth was 40 microns, and this was completely elastic relative displacement. With all implants, the micromotion between the cortex and the stem was always greatest over the uncoated portion of the stem. Four of the implants were proximally porous coated. With these, the micromotion was greater over the uncoated areas than with more extensively coated stems and was always greatest at the uncoated tip of the prosthesis. The amount of micromotion was directly related to the extent of porous coating on the implant. Maximum tip motion for the proximally coated implants was 210 micra, whereas for the fully porous-coated implants, it was 40 microns. In nine of the autopsies, the contralateral normal femur was obtained in addition to the femur containing the AML (the in vivo remodeled femur). These were used for comparative studies of strain shielding and femoral remodeling. Cortical strains were measured in the in vivo remodeled femora and were compared with measurements made in the contralateral normal femora before and following implantation of a stem identical to that present on the clinically treated side. The data showed major strain reductions in all the postmortem implanted normal femora. Comparison of the strain data from the postmortem implanted normal femora with those from the in vivo remodeled femora clearly indicated that extensive bone remodeling did not result in restoration of cortical strain levels anywhere near normal. Strain shielding continued to exist in all of the remodeled specimens, even up to 7.5 years after surgery. This strain shielding was associated with bone remodeling changes that resulted in regional reductions in bone mineral content that ranged from 7% to 78%. These observations are unique, important, and valuable in defining the in vivo function and clinical behavior of this type of porous-coated femoral component.

A quantitative evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty.

Dual-energy x-ray absorptiometry analysis was used to determine the periprosthetic bone-mineral content of ten femora that had been obtained at the autopsies of five elderly patients who had had an AML (anatomic medullary locking) prosthesis in situ for seventeen to eighty-four months. Clinical radiographs showed resorptive remodeling changes characteristic of femora containing this implant. Before the absorptiometry was performed, an identical prosthesis had been inserted into the contralateral, normal femur of each cadaver. The mean difference in the periprosthetic bone-mineral content between the remodeled femora and the femora in which the prosthesis had been implanted post mortem ranged from 7 to 52 per cent, with the bone-mineral content always less in the remodeled femora. The greatest mean decrease in bone-mineral content (45 per cent) occurred adjacent to the proximal one-third of the remodeled femora. The percentage decrease in periprosthetic bone-mineral content in the remodeled femora had an inverse linear relationship with the corresponding bone-mineral content of the contralateral control femora. Preoperative analysis of bone density may therefore be useful for prediction of the extent of resorptive bone-remodeling after total hip replacement.

The effects of comprehensive inpatient alcoholism treatment on measures of loss and grief.

Current research has identified a grief reaction in alcoholics undergoing inpatient treatment. The addition of a loss/grief experience to an existing comprehensive treatment regimen is examined to determine its ability to enhance loss/grief awareness in an experimental group of patients. Loss identification and grief awareness measures for this group are compared with like measures for a group undergoing the regular treatment program. No significant difference between the groups is reported. It is proposed that existing models of comprehensive treatment increase loss awareness and initiate a grieving process without the addition of a specialized treatment component dealing with loss and grief.

Hopelessness in the alcoholic patient.

The inability of the alcoholic to establish a meaningful posture towards the future has been articulated in terms of hopelessness. This study examines the effects of inpatient treatment on measures of hopelessness and implies that the decrease in hopelessness reported results from the restoration of a meaningful present during the course of treatment.

Loss identification in the treatment of alcoholism.

A variety of losses are clinically associated with the disease alcoholism. This article classifies the losses identified by an alcoholic population undergoing treatment and examines the effect of treatment on the process of loss identification. The enhanced loss awareness reported at the conclusion of treatment suggests the presence of a grieving process which can be distinguished from the depressive states commonly associated with alcoholism.