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Biomedical subjects

H E Rubash

Publications and source records attributed to H E Rubash.

At least 37 records · Page 2Linked to original sources
PubMed1998

Nitric oxide release by macrophages in response to particulate wear debris.

At the interface between a prosthetic implant and bone, macrophage interaction with particulate wear debris is a key event in the initiation of localized bone resorption, leading to aseptic loosening of the prostheses. Numerous investigators have reported that macrophages release a variety of cytokines and mediators including tumor necrosis factor, interleukin-1, prostaglandin E2, and interleukin-6 when they are stimulated with particulate wear debris. In this study, we have demonstrated that macrophages stimulated with particulate debris are also capable of releasing in copious amounts a key inflammatory chemical, nitric oxide. This release of nitric oxide was dependent upon the period of culture and the type and dosage of the challenging particles. Titanium-alloy particles were the most stimulatory, followed by commercially pure titanium and polymethyl-methacrylate. While the role of nitric oxide in osteolysis is not clearly understood, the literature suggests that it may be a key mediator in inhibiting DNA synthesis, in cell proliferation, and in stimulating PGE2 release. This finding enhances our understanding of the sequence of events occurring at the bone-implant interface during wear debris-mediated osteolysis, and exposes potential avenues to interrupt this sequence.

Animals↗
PubMed1998

Early inpatient rehabilitation after elective hip and knee arthroplasty.

CONTEXT: Inpatient rehabilitation after elective hip and knee arthroplasty is often necessary for patients who cannot function at home soon after surgery, but how soon after surgery inpatient rehabilitation can be initiated has not been studied. OBJECTIVE: To test the hypothesis that high-risk patients undergoing elective hip and knee arthroplasty would incur less total cost and experience more rapid functional improvement if inpatient rehabilitation began on postoperative day 3 rather than day 7, without adverse consequences to the patients. DESIGN: Randomized controlled trial conducted from 1994 to 1996. SETTING: Tertiary care center. PARTICIPANTS: A total of 86 patients undergoing elective hip or knee arthroplasty and who met the following criteria for being high risk: 70 years of age or older and living alone, 70 years of age or older with 2 or more comorbid conditions, or any age with 3 or more comorbid conditions. Of the 86 patients, 71 completed the study. INTERVENTIONS: Random assignment to begin inpatient rehabilitation on postoperative day 3 vs postoperative day 7. MAIN OUTCOME MEASURES: Total length of stay and cost from orthopedic and rehabilitation hospital admissions, functional performance in hospitals using a subset of the functional independence measure, and 4-month follow-up assessment using the RAND 36-item health survey I and the functional status index. RESULTS: Patients who completed the study and began inpatient rehabilitation on postoperative day 3 exhibited shorter mean (+/-SD) total length of stay (11.7+/-2.3 days vs 14.5+/-1.9, P<.001), lower mean (+/-SD) total cost ($25891+/-$3648 vs $27762+/-$3626, P<.03), more rapid attainment of short-term functional milestones between days 6 and 10 (36.2+/-14.4 m ambulated vs 21.4+/-13.3 m, P<.001; 4.8+/-0.8 mean transfer functional independence measure score vs 4.3+/-0.7, P<.01), and equivalent functional outcome at 4-month follow-up. CONCLUSION: These data showed that high-risk individuals were able to tolerate early intensive rehabilitation, and this intervention yielded faster attainment of short-term functional milestones in fewer days using less total cost.

Aged↗
PubMed1998

Pathogenesis of bone loss after total hip arthroplasty.

Bone loss with or without evidence of aseptic loosening is a long term complication after total hip arthroplasty (THA). It occurs with all materials and in all prosthetic systems in use or that have been used to date. Bone loss after THA can be a serious problem in revision surgery because bone deficiencies may limit reconstructive options, increase the difficulty of surgery, and necessitate autogenous or allogenic bone grafting. There are three factors adversely affecting maintenance of bone mass after THA: (1) bone loss secondary to particulate debris; (2) adaptive bone remodeling and stress shielding secondary to size, material properties, and surface characteristics of contemporary prostheses; and (3) bone loss as a consequence of natural aging. This chapter reviews the mechanisms of the primary causes of bone loss after THA.

Aging↗
PubMed1998

Failure of total hip arthroplasty with a precoated prosthesis. 4- to 11-year results.

A series of early femoral component failures prompted a detailed retrospective clinical and radiographic review of 176 hybrid cemented total hip arthroplasties using a polymethyl-methacrylate coated femoral prosthesis. All surgeries were performed using third generation cement techniques. Average length of followup was 6.3 years (range, 3-12 years). Twenty-one patients died, and one underwent revision surgery because of sepsis. Of the remaining 154 total hip arthroplasties, 23 (15%) of the femoral components failed (21 revised, two definitely loose). The average time to revision was 3.9 years. None of the acetabular components failed. Comparison between the failure and nonfailure groups revealed that poor cement mantles (Grades C or D) with distal cement mantle deficiencies were statistically significant predictors of femoral failure. The most common mechanism of failure was progressive, circumferential cement-bone interface osteolysis with relative preservation of the cement-metal interface. Debonding of the cement column from the prosthesis was a late finding and occurred in only 45% of failed cases. Incorporating the techniques of centralization and centrifugation significantly improved clinical results. Strengthening of the cement-prosthesis interface may magnify the deleterious effects of a poor cement mantle and predisposes the cement-bone interface to failure.

Aged↗
PubMed1998

Malrotation causing patellofemoral complications after total knee arthroplasty.

Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements without patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and tibial components. The group with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of combined internal rotation (1 degree-4 degrees) correlated with lateral tracking and patellar tilting. Moderate combined internal rotation (3 degrees-8 degrees) correlated with patellar subluxation. Large amounts of combined internal rotational (7 degrees-17 degrees) correlated with early patellar dislocation or late patellar prosthesis failure. The control group was in combined external rotation (10 degrees-0 degree). The direct correlation of combined (femoral and tibial) internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axial alignment. The epicondylar axis and tibial tubercle are reproducible landmarks which are visible on computed tomography scans and can be used intraoperatively. Using this computed tomography study can determine wether rotational malalignment is present and thus, whether revision of one or both components may be indicated.

Arthroplasty, Replacement, Knee↗
PubMed1998

Prospectus. Future trends in transfusion.

There are several emerging trends in perioperative transfusion that are promising in terms of clinical practice. These include modifications in transfusion practice, changes in blood bank procedures and philosophy, the use of autologous transfusion methods, and the development of new artificial blood substitutes. Refinement of current techniques will continue, and will be driven by several factors. The most significant recent changes in surgical practice relating to blood transfusion include a decreased reliance on the use of arbitrary transfusion triggers, and the increased use of various forms of autologous transfusion. Other clinical changes have been less obvious, such as changes in blood bank management practice. Similar factors drive the development of blood conservation strategies and artificial blood substitutes or O2 carriers. Both will play a role in reducing perioperative blood loss. The most likely scenarios involve use of blood substitutes in conjunction with various methods of blood conservation. Recent advances in blood banking have made the donor blood supply safer than ever before. Progress in the clinical setting and in the laboratory have widened the possibilities for treatment of perioperative blood loss, with attention to minimizing risk and cost, and maintaining safety for the patient.

Blood Banking↗
PubMed1997

Large amounts of polyethylene debris in the interface tissue surrounding bipolar endoprostheses. Comparison to total hip prostheses.

A histologic and biochemical comparison of interface membranes around femoral components of bipolar endoprostheses (n = 17) and total hip prostheses (n = 17) inserted without cement was conducted. The patients' profiles were similar in both groups with respect to age, sex, primary diagnosis, weight, and the interval between primary and revision arthroplasty. Macroscopically, marked circumferential abrasion of the polyethylene insert in the retrieved bipolar cups was noted. Histologic analysis revealed significantly larger amounts of polyethylene debris in the bipolar group. The membranes from the bipolar group also produced significantly greater amounts of prostaglandin E2 (P < .05). The inflammatory membranes associated with large amounts of polyethylene debris may have contributed to aseptic loosening and osteolysis in patients with a bipolar hip prosthesis.

Collagenases↗
PubMed1997

Effect of a centralizing device on cement mantle deficiencies and initial prosthetic alignment in total hip arthroplasty.

Sixty consecutive patients undergoing a primary hybrid total hip arthroplasty were randomized to receive a femoral component either with or without a distal centralizing device. The group with a centralizer had significantly fewer patients with cement mantle deficiencies (excessively thin areas of cement) than the group without a centralizer (P < .001). Furthermore, the centralizer group was, on average, in a neutral alignment, whereas the group without a centralizer was in a varus alignment (P < .001). It was concluded that the distal centralizing device significantly decreases the incidence of cement mantle deficiences and reproducibly aids in achieving a more neutral prosthetic alignment.

Bone Cements↗
PubMed1997

Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement.

Thirty-five patients who had had a primary total hip replacement with a porous-coated acetabular component inserted without cement had a revision procedure to treat pelvic osteolysis. The mean age at the time of the revision operation was forty-nine years (range, twenty-nine to eighty-five years). Forty-six distinct pelvic osteolytic lesions were noted radiographically around the thirty-five cups. These lesions ranged in size from 0.5 by 0.5 centimeter to 6.3 by 2.7 centimeters (mean, 2.6 by 1.7 centimeters). Fourteen of the thirty-five patients had no or only slight occasional pain at the time of diagnosis of the pelvic osteolysis, fifteen patients had pain attributed to a loose femoral component, one had pain related to a spontaneous fracture of the greater trochanter, and one had pain related to recurrent subluxation. The remaining four patients had pain in the groin despite radiographically stable implants. All of the metal-backed porous-coated acetabular components were stable according to the preoperative radiographs, and the stability was confirmed at the time of the revision. The metal shell was left in place and the acetabular liner was exchanged in all thirty-five patients. The osteolytic lesions were debrided, and thirty-four of the forty-six lesions were filled with allograft bone chips. The patients were evaluated a minimum of two years (range, two to five years; mean, 3.3 years) after the revision operation, and all thirty-five sockets were found to be radiographically stable. The bone grafts appeared to have consolidated, and none of the osteolytic defects had progressed. One-third of the lesions were no longer visible on radiographs, regardless of whether or not they had been filled with bone graft. The remaining lesions had decreased in size. It appears that, in the short-term, exchange of the liner and debridement of the granuloma, with or without use of allograft bone chips in the osteolytic defect, is a reasonable alternative to revision of the socket provided that the metal shell is solidly fixed at the time of the revision operation. If the metal shell has been markedly damaged by the femoral head, the locking mechanism for the polyethylene liner is not intact, or a satisfactory replacement liner is not available, then revision of the porous-coated acetabular component is indicated. These results must be considered preliminary. Since osteolysis may take several years to redevelop after a revision, additional follow-up is required.

Acetabulum↗
PubMed1997

Identification of inducible nitric oxide synthase in human macrophages surrounding loosened hip prostheses.

Exposure of rodent macrophages to certain cytokines and endotoxin results in the synthesis of inducible nitric oxide synthase (iNOS or NOS-II) leading to the production of large amounts of nitric oxide (NO). Cultures of human macrophages, in contrast, do not produce iNOS after cytokine stimulation, and their ability to act as a physiological source of NO remains questionable. Here we have used immunohistochemistry and in situ hybridization to demonstrate the presence of iNOS within human macrophages present in the interfacial membrane and pseudocapsule that surround failed prosthetic hip joints. Synovial tissue recovered from normal human joints did not express iNOS. Many of the iNOS-positive macrophages within the interfacial membrane had phagocytosed large amounts of polyethylene wear debris, suggesting a role for phagocytic stimuli in inducing iNOS in human macrophages. These findings additionally support a role for NO in modulating the localized bone resorption that accompanies the aseptic loosening of prosthetic joints.

Aged↗
PubMed1997

The John Charnley Award. Inhibition of wear debris mediated osteolysis in a canine total hip arthroplasty model.

In this study the efficacy of an oral bisphosphonate therapy to inhibit wear debris mediated bone resorption was evaluated in a canine total hip replacement model. Adult canines were randomized to three groups (n = 8 each) with a right uncemented total hip replacement performed on each animal. Group I (control) received no particulate debris. In Groups II and III, a mixture of 1 x 10(9) particles were introduced into the proximal femoral gap intraoperatively. The particle mixture consisted of fabricated ultra high molecular weight polyethylene (mean 2.3 microns, 90% by number), titanium alloy (mean 3.1 microns, 5%), and cobalt chrome alloy (mean 0.8 micron, 5%). Group III canines additionally received oral drug therapy (5 mg once a day, alendronate sodium) which was begun on postoperative Day 7 and continued until the time of sacrifice. Postoperatively, all animals were allowed 24 weeks of full ambulation before euthanasia. Radiographs obtained preoperatively, postoperatively, and at time of sacrifice were evaluated for periprosthetic osteolysis. Interfacial tissues were examined histologically and placed in organ culture and the supernatants were assayed for prostaglandin E2 and interleukin-1. One animal receiving debris (Group II) suffered a periprosthetic fracture and was sacrificed from the study. Radiographically, one of eight Group I (control) and six of seven canines from Group II (debris) had periprosthetic radiolucencies with endosteal scalloping develop. In contrast, only one of eight animals from Group III (debris + alendronate) had periprosthetic radiolucencies develop. Whereas tissues from control animals were mostly fibrous and acellular, tissues from both experimental groups had significant macrophage infiltration. Levels of prostaglandin E2 and interleukin-1 were elevated significantly in periprosthetic tissues from both experimental groups compared with controls. Continuous administration of alendronate effectively inhibited bone lysis for the 24-week duration of the study. This is consistent with the literature indicating that alendronate is incorporated in the mineralizing matrix making it refractory to osteoclastic resorption. This report has significant clinical implications for controlling the most common cause of implant failure.

Alendronate↗
PubMed1997

Free vascularized fibula grafting for the treatment of osteonecrosis of the femoral head.

Sixty-five patients (88 hips) who received free vascularized fibula grafting for treatment of osteonecrosis of the femoral head at the University of Pittsburgh Medical Center, were followed for at least 3 years (average followup, 5.5 years; range, 3-7 years). There were 46 men and 19 women with an average age of 37 years (range, 20-52 years). All patients were evaluated using history, physical examination, Harris Hip Score, anteroposterior and lateral radiographs, and magnetic resonance images. The classification system of Steinberg et al (1995) was used to stage the disease. At final evaluation, 31 hips (35.2%) were rated excellent (Harris Hip Score > 90 points, minimal or no pain), 30 hips (34.1%) were rated good (Harris Hip Score 80-89 points, slight pain), seven hips (8%) were rated fair (Harris Hip Score 70-79, slight or moderate pain), and 20 hips (22.7%) were rated poor (Harris Hip Score < 70, pain). Twenty hips in 17 patients required total hip arthroplasty. In the remaining hips, the disease apparently arrested and the contour of the femoral head was preserved. Kaplan-Meier survivorship analyses showed that the probability of conversion to total hip arthroplasty within an average of 5.5 years after free vascularized fibula grafting was 28% for Stage II hips and 38% for Stages III and IV hips. The hip survival rate for subgroups at 5.5 years was 100% for Stages IC and IIA, 94% for Stage IIB, 50% for Stage IIC, 80% for Stage IIIB, 58% for Stage IIIC, 72% for Stage IVA, and 58% for Stage IVB. Free vascularized fibula grafting is a reliable operation and can preserve hip function and diminish pain successfully.

Adult↗
PubMed1996

Technique for generating submicrometer ultra high molecular weight polyethylene particles.

Ultra high molecular weight polyethylene wear debris is believed to have a major role in aseptic loosening of prosthetic joints. In order to study the cellular and host response to this and other such particulate debris, a source of fine ultra high molecular weight polyethylene debris is needed. We have described a technique to fracture the GUR 4150 primary ultra high molecular weight polyethylene grain, which reproducibly generated particles less than 1 micron in size. Furthermore, the particle morphology was similar to that of ultra high molecular weight polyethylene particles generated in vivo and retrieved from interfacial tissues. The fabricated polyethylene particles ranged from 0.1 to 33 microns in diameter, with a mean of 2.3 +/- 0.2 micron. Sixty percent of the particles were smaller than 1 micron and 90% were smaller than 7 microns. Using filtration and sedimentation, it is possible to acquire finer particle fractions. These particles are currently being used for biological response studies.

Microscopy, Electron, Scanning↗
PubMed1996

Effect of superior and superolateral relocations of the hip center on hip joint forces. An experimental and analytical analysis.

With the extensive use of uncemented acetabular components in total hip arthroplasty, relocation of the hip center has become increasingly necessary to avoid bulk grafts and to promote contact between the porous prosthetic surface and bone. Compared with the anatomic hip center, superolateral relocation theoretically results in higher hip joint forces and has been shown in cemented acetabular components to result in an increased clinical failure rate. This study experimentally and analytically compared the hip joint forces in normal, superior, and superolateral hip center locations during both single-leg stance and stairclimbing, performing this comparison over a wide range of hip joint applied flexion moments. An advanced loading fixture was designed to allow any applied moment to be set independently of femoral position, incorporating all three major muscle groups active in stairclimbing position: extensors, abductors, and adductors. For all positions and moments tested, it was found that superolateral relocation caused significant increases in the total hip joint force, but did not affect the nonsagittal force component. Also, superior-only hip center relocation did not significantly affect the total joint force magnitudes or directions. The force increase on hip center lateralization can be attributed to a corresponding increase in the adduction moment. Results from the static analytical model developed supported these findings. The results of this study suggest that superolateral hip center relocation should be avoided and that superior-only relocation may be mechanically acceptable within the confines of the osseous anatomy of the acetabulum.

Biomechanical Phenomena↗
PubMed1996

Revision total hip arthroplasty with a retroperitoneal approach to the iliac vessels.

Although vascular complications during revision total hip arthroplasty are rare, the results can be devastating. Reports in the literature describe staged operations, with the first procedure being abdominal to remove cement and/or the acetabular component followed by a second joint reconstruction procedure. A protocol was developed that combines a retroperitoneal approach with revision total hip arthroplasty in one operative procedure in patients at risk for vascular injury. The patient first undergoes a retroperitoneal incision and the iliac artery and vein are dissected free of surrounding tissue. A silicone loop is placed around the iliac artery and vein and brought out through the wound. The wound is temporarily closed using staples. Revision total hip arthroplasty then proceeds in the usual fashion. If hemorrhage is encountered, bleeding can be rapidly controlled by tensioning the abdominal vessel loops and opening the incision for exposure to the vessels. No complications have been encountered in 23 patients when using this approach.

Aged↗