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Biomedical subjects

B N Stulberg

Publications and source records attributed to B N Stulberg.

At least 19 recordsLinked to original sources
PubMed1999

Multidirectional deformation in fully congruent acetabular components.

Most clinical studies have used femoral head migration as an index of acetabular wear, but a previous study showed multiple wear vectors in 30% of retrieved acetabular components with noncongruent liners. The origin of multiple wear vectors is unclear, and it has been suggested that polyethylene creep in a noncongruent shell might influence deformation on the articular surface. We used shadowgraph and volumetric methods to evaluate the extent and direction of surface deformation of 37 retrieved polyethylene liners that were fully congruent to a single design of metal backing. The results show that multiple deformation vectors are relatively common in retrieved acetabular cups (27% in this study) and are independent of congruency between liner and metal backing, rim impingement, and backside creep. Polyethylene liners with multiple wear vectors were significantly thinner than those of cups with a single vector. The origin of multiple vectors is still unclear, but clinical and laboratory studies measuring linear wear alone without recognizing multiple vectors underestimate total in vivo volumetric wear.

Acetabulum↗
PubMed1999

Relationship between wear debris particles and polyethylene surface damage in primary total knee arthroplasty.

To study relationships between design and wear, particles were isolated from tissues around 75 failed primary total knee prostheses, and particle size and concentration were compared with the extent and distribution of wear on superior and inferior polyethylene surfaces of the corresponding implants. Twenty-four heat-pressed, posterior cruciate ligament (PCL)-retaining (group I: PCA knee), 19 non-heat-pressed, PCL-retaining with relatively flat surfaces (group II: AMK, Kinematic, Microloc, Ortholoc), 14 non-heat-pressed, PCL-retaining with relatively congruent surfaces (group III: Townley Arizona), and 18 PCL-resected implants (group IV: Insall-Burstein, Total Condylar) were evaluated. Groups III and IV had fewer particles, smaller particles, and less surface damage than groups I and II. Implants with third-body wear had relatively small debris particles; those with thinner polyethylene had more severe surface delamination and more wear between liner and metal base. Groups I and II had more rotationally asymmetric wear patterns than groups III and IV. The size and concentration of debris particles might reflect, in part, different dominant wear mechanisms among implants of different designs.

Adult↗
PubMed1998

Results of 2-stage reimplantation for infected total knee arthroplasty.

Optimum treatment of the infected total knee arthroplasty has not been clearly established. To clarify the efficacy of two-stage reimplantation, experience with 66 infected total knee arthroplasties in 64 patients who had been treated with 2-stage reimplantation total knee arthroplasty between September 1980 and October 1993 was reviewed. Of these, 55 knees in 54 patients were available for follow-up examinations at an average of 61.9 months (range, 28-146 months). The initial diagnoses were rheumatoid arthritis (14 knees) and osteoarthritis (41 knees). Reimplantation was successful in 80.0% of knees with low-virulence organisms (coagulase-negative Staphylococcus, Streptococcus), 71.4% with polymicrobial organisms, and 66.7% with high-virulence organisms (methicillin-resistant Staphylococcus aureus). Reimplantation was successful in 82% of patients with osteoarthritis and in 54% of patients with rheumatoid arthritis (P = .024). The success rate was 92% if infection occurred after primary arthroplasty but only 41% if after multiple previous knee operations (arthroscopy, osteotomy, or revision total knee arthroplasty) (P < .001).

Adult↗
PubMed1997

Effect of femoral head diameter on tissue concentration of wear debris.

Although several studies have reported the physical properties of debris particles in tissues adjacent to failed total joint implants, few have correlated the results of particle analysis with other clinical and implant variables believed to influence implant wear. We retrospectively analyzed 41 fibrous membranes (from 35 patients) adjacent to failed acetabular cups from a single manufacturer and studied the relationship between three different femoral head sizes (26, 28, and 32 mm) and the characteristics of wear debris in the adjacent tissues. All total hip prostheses consisted of modular cobalt-chromium alloy femoral heads articulating with titanium-alloy-backed ultrahigh molecular weight polyethylene (UHMWPE) acetabular components from a single manufacturer. Large femoral head diameter (32 mm) was found to correlate significantly with large particle size (diameter and surface area, p < 0.05), high tissue concentration of particles (particle volume/gram of tissue, p < 0.01), and high rate of particle production (particles volume/month, p < 0.05). The results of these quantitative assays support the findings of radiographically based clinical studies that show higher volumetric wear associated with 32 mm femoral head components.

Adult↗
PubMed1997

Prevention of deep-vein thrombosis after total hip arthroplasty. Comparison of warfarin and dalteparin.

The effectiveness and safety of warfarin were compared with those of a low-molecular-weight heparin (dalteparin) for the prevention of deep-vein thrombosis after total hip arthroplasty in a prospective, randomized, multi-institutional trial. Patients who were older than eighteen years of age and were scheduled to have an elective primary or revision total hip arthroplasty were eligible; 580 patients were randomized, 550 had the operation and received prophylaxis, and 382 had evaluable venograms. Prophylaxis was provided either with warfarin beginning the night before the operation or with dalteparin beginning two hours before the operation and was continued until venography was performed. Bleeding was assessed on the basis of intraoperative blood loss, transfusion requirements, a decrease in hematocrit, and clinically identified bleeding complications. The prevalence of deep-vein thrombosis was found to be significantly lower in the patients who had received dalteparin than in those who had received warfarin (twenty-eight [15 per cent] of 192 patients compared with forty-nine [26 per cent] of 190 patients; p = 0.006). Deep-vein thrombosis occurred in the calf veins of twenty-one patients (11 per cent) who had received dalteparin and of forty-three patients (23 per cent) who had received warfarin; this difference was significant (p = 0.003). Proximal deep-vein thrombosis occurred in ten patients (5 per cent) who had received dalteparin and in sixteen patients (8 per cent) who had received warfarin; however, with the numbers available, no significant difference could be detected (p = 0.185). We also could not detect a significant difference with regard to the intraoperative and postoperative blood loss, the decrease in hematocrit, and the prevalence of major bleeding complications between the two groups; however, the patients who had received dalteparin had a significantly higher prevalence of bleeding complications involving the operative site (p = 0.03), and a significantly greater percentage required postoperative transfusions (p = 0.001). We concluded that preoperative prophylaxis with dalteparin is significantly more effective than that with warfarin in preventing deep-vein thrombosis after total hip arthroplasty. The greater effectiveness of dalteparin must be considered, however, in light of an increased need for postoperative transfusions and an increase in the prevalence of wound-related bleeding complications.

Anticoagulants↗
PubMed1997

Uncemented total hip arthroplasty in osteonecrosis: a 2- to 10-year evaluation.

All patients undergoing uncemented total hip arthroplasty for end stage hip disease related to osteonecrosis of the femoral head were assessed prospectively between November 1983 and October 1992. The results of clinical evaluation using the Harris Hip score and radiographic assessment of fixation were analyzed to identify features of success or failure that may be unique to this population. Four different stem types and 4 different acetabular components were used. Sixty-four patients had 98 hips implanted during the time of the study. The 42 male and 22 female patients averaged 41 years of age (range, 21-69 years). Average followup was 87.3 months (7.3 years; range, 31-134 months). The cause of osteonecrosis was corticosteroids (42 hips), alcohol (27 hips), trauma (5 hips), and other (24 hips). Three patients (5 hips) have died and 4 patients (6 hips) are lost to followup. At last followup 65 of 87 hips (75%) remained radiographically stable and clinically functional, 18 of 87 (21%) have been revised, and 4 were failing (osteolysis). Of the 22 hips with revision or impending failure, 4 were for technical reasons on the femoral side and 18 were for acetabular wear. Patient factors such as weight or underlying disease state did not seem to influence the ability to achieve stable fixation or contribute to accelerated failure. Failures related primarily to problems of first generation devices including accelerated wear of acetabular components, technical issues of femoral component placement (undersizing of components or femoral fracture), and the use of noncircumferentially coated femoral components. Age may be a factor in early failure. This 10-year experience with total hip arthroplasty for the patient with end stage hip disease due to osteonecrosis suggests that uncemented total hip arthroplasty can be applied predictably to this younger, potentially more active patient population.

Adult↗
PubMed1996

Comparison and quantitation of wear debris of failed total hip and total knee arthroplasty.

To compare the physical properties of debris particles associated with failed total hip and total knee arthroplasty, we applied a recently developed assay to electronically characterize the size, number, and composition of debris particles isolated from tissues adjacent to failed implants. We identified 21 samples (from 20 patients) of hip synovia and 35 samples (from 32 patients) of knee tissues that had been obtained at the time of revision arthroplasty. There were 12 females and 9 males in the hip group, and 16 females and 19 males in the knee group. Primary arthroplasty was performed for osteoarthritis (OA, 15 cases) or rheumatoid arthritis (RA, 6 cases) in the hip, and for OA (23) or RA (12) in the knee. Patients ranged in age from 23 to 85 (mean 59 years) for total hip, and from 27 to 84 (mean 61 years) for total knee arthroplasty. Implantation duration was from 5 to 123 months (mean 37.8) for total hip, and from 11 to 123 months (mean 63.1) for total knee arthroplasty. All of the implants were composed of cobalt-chromium alloy articulating with ultrahigh-molecular-weight polyethylene. The number of particles smaller than 10 microns ranged from 1.04 x 10(8)/g to 1.91 x 10(10)/g in the hip, and from 6.69 x 10(8)/g to 2.13 x 10(10)/g in the knee. Energy-dispersive X-ray spectroscopy and polarized light analysis showed both polyethylene and metal particles in most cases. The mean diameter of particles smaller than 10 microns was 0.72 +/- 0.2 microns in the hip, and 0.74 +/- 0.1 microns in the knee. Evaluation of particles larger than 10 microns showed a larger range of particle size in knee tissues (maximum 6.1 mm, mean 283 microns), than in the hip tissues (maximum 826 microns, mean 81 microns) (p < 0.001). Very small particles are common in both groups, but it appears that a larger range of particle sizes is present adjacent to failed knee than to failed hip prostheses. The higher frequency of large particles in failed knee prostheses probably reflects the perceived higher rate of delamination and fragmentation of tibial and patellar compared to that of acetabular polyethylene.

Adult↗
PubMed1996

Characterization of debris adjacent to failed knee implants of 3 different designs.

Wear debris particles have been associated with bone resorption and loosening of total joint implants. To characterize the wear particles around failed knee prostheses, tissues adjacent to 47 implants of 3 different designs were evaluated: 29 were posterior cruciate ligament retention type (Group I), 12 were posterior cruciate ligament sacrificing or substituting (Total Condylar, Insall-Burstein), (Group II), and 6 were mobile bearing (posterior cruciate ligament retaining LCS), (Group III). Wear particles were isolated and evaluated using electronic particle quantitation and scanning electron microscopy. The corresponding implants were also evaluated, and the surface damage quantified. The number of particles smaller than 10 microm ranged from 8.9 to 45.8 x 10(9) per gram of tissue (dry weight). Particle number directly correlated with duration of implantation. Group I implants had larger particles, and showed greater surface damage than the other 2 designs. Polyethylene surface damage significantly correlated with particle size more than 10 microm in length. Particle number showed a significant inverse correlation with the thickness of the polyethylene. These results support previous mechanical and retrieval studies suggesting that increased wear may be associated with thinner polyethylene, and there are differing degrees and patterns of wear based on implant design.

Adult↗
PubMed1996

The porous-coated anatomic total hip prosthesis: failure of the metal-backed acetabular component.

One hundred and ninety-nine total hip arthroplasties were performed, between 1983 and 1987, in 173 patients by three surgeons using the initial design of the porous-coated anatomic prosthesis. The acetabular component was a preassembled, metal-backed polyethylene device, with beads sintered to the metal backing to allow bone ingrowth and two pegs for initial fixation. Twenty-three acetabular components (12 percent) failed because of either migration or severe osteolysis. The radiographic appearance of osteolysis was positively associated with the duration that the implant had been in situ (p < 0.001). The prevalence of osteolysis was also significantly greater in acetabular components with an outer diameter of fifty-five millimeters or less (a polyethylene thickness of 8.5 millimeters or less) (p = 0.03). Thirteen hips were revised at a mean of 69.5 months (range, thirty-three to ninety-one months) after the index operation. Examination of the retrieved acetabular components revealed extensive polyethylene damage on the articular and back surfaces of the liners. Cracks in the polyethylene rim of the liner and deformation of the anti-rotation notch in the polyethylene rim were common findings. The density of the polyethylene was greater than expected, and more particles than anticipated had not fused with the surrounding polyethylene. The results of this study suggest that factors related to both the design and the material contributed to the failure of these porous-coated anatomic acetabular components.

Acetabulum↗
PubMed1996

Characterization and comparison of wear debris from failed total hip implants of different types.

Particles of wear debris have been associated with loosening of implants and with osteolysis, but few studies have examined the relationship between characteristics of the implant and clinical variables and the concentration of particles isolated from periarticular tissues. We isolated and quantified particles of wear debris from orthopaedic implants in 123 tissue samples that had been obtained adjacent to a failed total hip prosthesis from eighty-eight patients. The concentration of these particles in the tissue and the size of the particles were then analyzed in relation to patient and implant-related variables. The number of particles ranged from 8.5 x 10(2) to 5.7 x 10(11) per gram of tissue (dry weight). More particles were found adjacent to failed titanium-alloy stems that had a cobalt-chromium-alloy modular head and failed titanium-alloy-backed cups than were found adjacent to all-cobalt-chromium-alloy prostheses. In addition, fewer particles were found adjacent to implants with a twenty-eight-millimeter femoral head than were found adjacent to implants with other femoral head sizes. Univariate analysis also showed correlations between a high concentration of particles and fixation without cement, an implant that had been in situ for a long duration, a young patient age, and an initial clinical diagnosis of avascular necrosis. Biopsy specimens from the proximal femoral membranes had higher concentrations than those from the joint capsules or the acetabular membranes. Although only five specimens were obtained directly from osteolytic lesions, the concentration of particles in those specimens was higher than that in biopsy specimens from other sites. Although many univariate correlations were identified, stepwise correlation regression analysis showed that the composition of the implant and the size of the modular femoral head were most strongly related to the concentration of debris in tissue.

Adult↗
PubMed1995

Computed tomography analysis of proximal tibial coverage.

Researchers of this study used computed tomographic studies of the proximal tibia for patients undergoing total knee arthroplasty to determine basic morphologic data of size, shape, and area of varying levels from the articular surface. Five off-the-shelf tibial component shapes (4 symmetric, 1 asymmetric) were templated to determine the fit of the components at the various resection levels. Seventy-two knees were assessed at 2-mm, 68 at 5-mm, 40 at 8-mm, and 17 at 11-mm resection levels. Significant differences in fit and percentage of total area of coverage were identified. Fit was significantly better for asymmetric as compared with the symmetric components (p = 0.001) at all levels of resection. Fit was significantly worse for each component as the resection depth increased. This information can serve as a bridge to clinical and laboratory data in identifying the importance of tibial component fit to the overall performance of a total knee arthroplasty design.

Female↗
PubMed1994

The use of muscle flaps for salvage of failed total knee arthroplasty.

Deep infections occur in 1-5% of all patients undergoing total knee arthroplasty, and may result in failure of the prosthesis and subsequent arthrodesis. Two-stage reimplantation is often successful, but depends upon the presence of good soft tissue coverage. We have treated 9 patients in whom chronic infection developed which required removal of the prosthesis, debridement, and implantation of antibiotic impregnated spacers for control. These patients all had poor quality soft tissue cover precluding prosthesis reimplantation. The use of muscle flaps resulted in 7 of the 9 patients having successful reimplantation of a prosthesis and remaining free of infection in a follow-up ranging from 1-5 years.

Adult↗
PubMed1993

Uncemented acetabular components. Histologic analysis of retrieved hydroxyapatite-coated and porous implants.

Histologic sections of five hydroxyapatite-coated acetabular components retrieved at autopsy (2 dual geometry and 3 threaded cup designs) were analyzed, and the extent and pattern of bone apposition were compared with that of an uncoated, porous (beaded) dual geometry acetabular cup that had been removed for repeated dislocations. The results show hydroxyapatite and bone apposition most prominent in areas of likely load transmission, primarily around the peripheral rim of the dual-geometry cups and at the peaks of the threads of the screw cups. Hydroxyapatite and bone may have been removed by remodeling from the grooves between the threads. Although no significant wear debris was identified, the screw holes were incompletely covered by bone. The dual-geometry designs generally showed somewhat more bone apposition than the threaded cups, but all implants demonstrated less bone than might have been predicted from radiographs.

Adult↗
PubMed1991

Preoperative nutritional status of total joint patients. Relationship to postoperative wound complications.

The records of 217 consecutive patients who underwent a primary total hip or total knee arthroplasty were reviewed for preoperative and postoperative nutritional status. Fifty-seven patients had a lymphocyte count of less than 1,500 cells/mm3, four patients had an albumin level of less than 3.5 g/dL, and two patients had both, giving a 27% incidence of indices indicative of preoperative nutritional depletion. Patients without wound complications had an average preoperative lymphocyte count of 1,995 (+/- 631), compared to 1,638 (+/- 491) for those with persistent serous drainage from their wounds, and 1,553 (+/- 419) for those patients with a major wound complication (P = .002). The average albumin levels were 4.30 (+/- 0.33), 4.22 (+/- 0.31), and 4.13 (+/- 0.54), respectively. Patients with rheumatoid arthritis were compared to those with osteoarthritis and were found to have significantly lower preoperative albumin levels. They were three times as likely to develop a major wound complication. Patients on immunosuppressive medications had significantly lower preoperative lymphocyte counts, lower albumin levels, and higher complication rates (P = .04). After operation, lymphocyte counts of all patients dropped to an average of 57% of their preoperative values, and albumin levels dropped to 72% of their preoperative values. No nutritional parameters had returned to their preoperative levels by 10 postoperative days. For all patients, a preoperative lymphocyte count of less than 1,500 cells/mm was associated with a five times greater frequency of developing a major wound complication, and an albumin level of less than 3.5 g/dL had a seven times greater frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A new model to assess tibial fixation in knee arthroplasty. I. Histologic and roentgenographic results.

A model to assess tibial fixation in knee arthroplasty is described. Eighteen mongrel dogs were implanted with a right tibial hemiarthroplasty. Implantation was of a press-fit, smooth implant (eight dogs) or a titanium alloy beaded device (ten dogs). Animals were studied at six, 12, 18, and 24 weeks. Roentgenographic and histologic analysis was performed for all implants. All animals were ambulatory. Roentgenographically, smooth implants showed progressive radiolucencies with increasing trabecular sclerosis under the implants. These changes were less prominent under the porous implants. Histologically, fibrous interfaces were identified focally under all implants but were thicker under smooth devices. Eighteen- and 24-week specimens showed substantial ingrowth into the porous pegs but minimal ingrowth into the porous plateau. Concurrent histologic and biochemical evaluation in dogs demonstrates the possible fate of implants in knee arthroplasty in human beings. As has been observed, histologic analyses suggest that clinically satisfactory results do not constitute evidence of stabilization by bone ingrowth.

Animals↗
PubMed1991

A new model to assess tibial fixation. II. Concurrent histologic and biomechanical observations.

A tibial hemiarthroplasty model was designed to allow concurrent histologic and biomechanical analysis of the tibial implant-bone interface. In this study, micromotion was visually observed at the implant-bone interface of cemented and uncemented implants. Six dogs had staged bilateral implantation. Biomechanical analysis of three- and 12-month specimens was correlated with histologic analysis of the same specimen. Load transmission involved compression of trabecular bone and fibrous tissue at the interface. Failure of the interface occurred through cyclic fatigue and microfracture of trabeculae. Micromotion was seen at all interfaces, porous or smooth, cemented or uncemented. Displacement was greatest under an eccentrically loaded plateau. Micromotion at ingrown and cemented interfaces was because of trabecular compression. Uncemented smooth devices and uncemented porous devices with fibrous fixation of the plateau appeared unstable. The cemented implants and a single uncemented implant studied at 12 months showed no interface micromovement. The absence of micromovement in the uncemented implant was associated with subsidence and with ingrowth of 30% into the porous peg and porous plateau.

Animals↗