William A. Jiranek

Production of cytokines around loosened cemented acetabular components. Analysis with immunohistochemical techniques and in situ hybridization.

The chronic inflammatory response to wear particles from orthopaedic joint implants is believed to cause osteolysis and to contribute to prosthetic loosening. Previous in vitro experiments have demonstrated that particulate debris from joint implants causes cells in culture to release products that have been implicated in this pathological bone resorption. The purpose of the current study was to investigate the in vivo features of this complex process in patients who had had a total hip replacement. Membraneous tissue was obtained from the cement-bone interface of ten polyethylene acetabular components that had been revised for aseptic loosening in ten patients. The immunoperoxidase technique, which involves the use of specific antibodies for each cell type, showed that macrophages were the predominant cellular constituents but also that fibroblasts, many of which were not identified on plain histological study, were present and were actively producing collagen. T lymphocytes were present variably, but they generally composed less than 10 percent of the cells. Particulate debris (polyethylene, methylmethacrylate, and metal) was present in all membrane specimens but was intracellular only in macrophages and multinucleated giant cells. 35S-labeled nucleic-acid probes, complementary to human interleukin-1-beta and to platelet-derived growth-factor-2 messenger RNA (mRNA), were hybridized with serial tissue sections. Hybridization demonstrated interleukin-1-beta mRNA predominantly in macrophages, and not in fibroblasts or in T lymphocytes to any major extent. In contrast, immunolocalization demonstrated interleukin-1-beta protein on both macrophages and fibroblasts, suggesting that macrophages release interleukin-1-beta, which then binds to both fibroblasts and macrophages. Platelet-derived growth-factor transcripts were found in both macrophages and fibroblasts.

Antibiotic-Loaded Bone Cement for Infection Prophylaxis in Total Joint Replacement

Use of antibiotic-loaded bone cement for prophylaxis against infection is not indicated for patients not at high risk for infection who are undergoing routine primary or revision joint replacement with cement. The mechanical and elution properties of commercially available premixed antibiotic-loaded bone-cement products are superior to those of hand-mixed preparations. Use of commercially available antibiotic-loaded bone-cement products has been cleared by the United States Food and Drug Administration only for use in the second stage of a two-stage total joint revision following removal of the original prosthesis and elimination of active periprosthetic infection. Use of antibiotic-loaded bone cement for prophylaxis against infection in the second stage of a two-stage total joint revision involves low doses of antibiotics. Active infection cannot be treated with commercially available antibiotic-loaded bone cement as such treatment requires higher doses of antibiotics.

Orthopaedic surgeon workforce and volume assessment for total hip and knee replacement in the United States: Preparing for an epidemic

The demand for health-care services in general, and musculoskeletal care in particular, is expected to increase substantially in the United States because of the growth of the population, aging of the population, public expectations, economic growth, investment in health-care interventions, and improved diagnosis and treatment. The impact of an aging population is demonstrated by the fact that, in 2000, the eleven most costly medical conditions in the United States were far more prevalent among the elderly, and the population of elderly Americans is increasing. It is not clear that the future supply of physicians will be sufficient to meet the increasing demand for health care. The supply of American physicians is limited by the aging and retirement of current physicians, medical school graduation class size of allopathic medical doctors and osteopathic physicians, and United States immigration policies, which limit the number of physicians entering the country. Furthermore, among active physicians, the “effective physician supply” is limited by gender and generational differences, lifestyle choices, changing practice patterns, and variability in physician productivity. At current physician production levels, the ratio of physicians to population will peak between 2015 and 20201. Between 2000 and 2020, the demand for orthopaedic services in this country will increase by 23% while the supply of orthopaedic surgeons will increase by only 2% during the same interval2. During the next few decades, the demand for total joint arthroplasties in the United States may not be met because of an inadequate supply of total joint arthroplasty surgeons. This hypothesis or concern is based on data and trends associated with the prevalence of total joint arthroplasty, projected volumes of total joint arthroplasty, workforce trends in total joint arthroplasty, and reimbursement for total joint arthroplasty. The purposes of this paper are to evaluate the validity of this …

Prevalence of Total Hip and Knee Replacement in the United States

BACKGROUND Descriptive epidemiology of total joint replacement procedures is limited to annual procedure volumes (incidence). The prevalence of the growing number of individuals living with a total hip or total knee replacement is currently unknown. Our objective was to estimate the prevalence of total hip and total knee replacement in the United States. METHODS Prevalence was estimated using the counting method by combining historical incidence data from the National Hospital Discharge Survey and the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases from 1969 to 2010 with general population census and mortality counts. We accounted for relative differences in mortality rates between those who have had total hip or knee replacement and the general population. RESULTS The 2010 prevalence of total hip and total knee replacement in the total U.S. population was 0.83% and 1.52%, respectively. Prevalence was higher among women than among men and increased with age, reaching 5.26% for total hip replacement and 10.38% for total knee replacement at eighty years. These estimates corresponded to 2.5 million individuals (1.4 million women and 1.1 million men) with total hip replacement and 4.7 million individuals (3.0 million women and 1.7 million men) with total knee replacement in 2010. Secular trends indicated a substantial rise in prevalence over time and a shift to younger ages. CONCLUSIONS Around 7 million Americans are living with a hip or knee replacement, and consequently, in most cases, are mobile, despite advanced arthritis. These numbers underscore the substantial public health impact of total hip and knee arthroplasties.

Yearly Incidence of Unicompartmental Knee Arthroplasty in the United States

Our purpose was to estimate the incidence of unicompartmental knee arthroplasty in the United States. Three major implant manufacturers provided data over an 8-year period from 1998 to 2005. In addition, a database from 44 hospitals was used to derive national estimates for implants manufactured by all other companies. The incidence of unicompartmental knee arthroplasty ranged from 6570 implants in 1998 to 44990 in 2005. Unicompartmental knee arthroplasty increased at an average rate of 32.5% during the study period compared with a 9.4% average increase in rate of total knee arthroplasty over the same period. Although unicompartmental arthroplasty is growing at triple the rate of total knee arthroplasty in the United States, the data suggest that unicompartmental implants currently account for less than 8% of all knee arthroplasty procedures.

Long-term results after Russe bone-grafting: the effect of malunion of the scaphoid.

Twenty-five patients had Russe anterior corticocancellous bone-grafting between 1973 and 1984 for twenty-six symptomatic established non-unions of the scaphoid. The mean duration of follow-up was eleven years (range, seven to eighteen years). Twenty-one (81 per cent) of the twenty-six scaphoid bones united. We developed two rating scales to evaluate the results of the operation. One scale, based on objective findings, included the radiographic appearance of the wrist, the range of motion, and strength; the other scale, based on subjective findings, comprised function, pain, perception of a decrease in performance because of limitation of motion or strength, and satisfaction. These scales were used to compare the objective and subjective results in patients who had a malunion of the scaphoid in which the lateral intrascaphoid angle was more than 45 degrees convex dorsally between the proximal and distal poles (a so-called flexion or humpback deformity, which results in extension of the proximal fragment of the scaphoid at the radiocarpal joint) with the results in patients who had no such deformity. The lateral intrascaphoid angle was more than 45 degrees in thirteen (50 per cent) of the twenty-six wrists. Although the difference in the objective results between the wrists that had a malunion and those that did not have a malunion was highly significant (p = 0.001), there was no significant difference in the subjective results between the two groups, including satisfaction of the patient (p = 0.39). Twenty-three patients (92 per cent) returned to full-time employment and twenty-two (88 per cent), to sports activities. Twenty-three patients (92 per cent) reported that they had pronounced relief of pain and that the procedure had improved their quality of life. The presence of this deformity of the scaphoid after bone-grafting for a symptomatic non-union was not predictive of a poor long-term subjective outcome.

Macrophage activation results in bone resorption.

Monocytes or macrophages from important accessory cells in the regulation of bone metabolism and destruction. Cells of the mononuclear phagocyte lineage form the precursor cells of the osteoclasts. Soluble products produced by activated macrophages regulate progenitor cell proliferation, recruitment, differentiation, and activity of osteoblasts and osteoclasts. After osteoclasts are removed from the resorption site, macrophages process bone surfaces and create a cement line before osteoblasts enter to form new bone. Although osteolysis associated with normal bone remodeling is seen as an osteoclast driven process, it may be that in chronic inflammation macrophage activation and vascular derangements lead to low pH, local bone demineralization (acid attack), and H+ mediated stimulation of the primary afferent nociceptive nerve fibers (bone pain). Osteoclasts are not able to attach to demineralized bone or to osteoid surfaces. However, if macrophages degrade the demineralized organic bone matrix, chemotactic factors and attachment sites for osteoclasts are produced. In such a scenario, the osteoclast-osteoblast mediated activation, resorption, and formation cycle would be secondarily activated. Such events may play a role in the most common orthopaedic problem related to macrophage activation, aseptic loosening of orthopaedic joint implants, which is secondary to a chronic foreign body reaction and to micromovement.

A COMPARISON OF THE MIDVASTUS AND PARAMEDIAN APPROACHES FOR TOTAL KNEE ARTHROPLASTY

This prospective, double-blinded evaluation of 24 osteoarthritic patients undergoing bilateral total knee replacement compared the midvastus and standard parapatellar approaches. The midvastus approach was found to offer an early advantage in terms of less pain and earlier return to function. There were no significant complications associated with the midvastus approach. This approach should be a part of the knee surgeons armamentarium.

Etiology of osteolysis around porous-coated cementless total hip arthroplasties.

The prosthetic components and tissues retrieved from 12 hips with osteolysis in association with well-fixed cementless porous-coated total hip prostheses (5 Porous Coated Anatomic, 6 Harris-Galante Porous, and 1 Omniflex) were examined using a variety specific techniques including electron microscopy, standard histology, immunohistochemistry, and particle identification. The patients were young and active. Extensive osteolysis developed in all 12 femurs and 3 acetabula between 36 and 84 months after arthroplasty (mean, 63 months). AH of the polyethylene liners were noted to be worn substantially (mean volumetric wear, 1140 ± 810 mm3). The wear was unrelated to the head diameter in this small number of cases. In all 12 cases, the articulating surfaces were wear polished and contained numerous fine multidirectional scratches, suggesting 3-body abrasive wear mechanisms in addition to adhesive wear liberating very small (micron to submicron) wear particles. In 4 cases, surface delamination and flaking of polyethylene were also found, suggesting fatigue wear liberating larger wear particles. Nine of 10 cobalt alloy heads showed numerous fine scratches with sharp edges presumably from 3-body abrasive wear. Corrosion and fretting at the femoral head-neck junction in 5 cases, burnishing of the femoral stem against bone in 4 cases, and metal staining of tissues opposite the porous coatings in 7 cases provided evidence for the liberation of fine metal particles from outside the articulation. Histologic and immunohistochemical studies of tissue in the regions of osteolysis in all cases showed numerous focal aggregates of KP1 antibody positive activated macrophages containing large amounts of submicron intracellular particles of polyethylene (presumably related to the 3-body abrasive wear polishing) and giant cells within a fibrous stroma. In 5 cases, some of the macrophages also contained submicron metal particles but smaller in numbers. T lymphocytes, plasma cells, and mast cells that might indicate hypersensitivity were found in 4 of the 12 cases (33%), and none of the cases had B lymphocytes. These data suggest that abrasive wear at the articulation leads to the liberation of abundant fine particulate wear debris of polyethylene into the tissues around cementless prostheses. Small amounts of particulate metal debris are also liberated from

Osteolysis around uncemented acetabular components of cobalt-chrome surface replacement hip arthroplasty

Ten cases of major osteolysis were identified in patients with hemispherical cobalt chrome acetabular components of cementless resurfacing total hip prostheses at follow-up examinations ranging from two to five years. All components were porous coated with cobalt chrome spheres and were stabilized initially with screws. Five patients were women and five were men, with ages ranging from 20 to 59 years. The radiolucent cystic lesions with peripheral rims of reactive bone formation appeared one to five years after the operation. They measured from 1.5 to 6 cm in the largest diameter and were most often found adjacent to the screws used to secure the acetabular components to the skeleton. On the radiographs, none of the components appeared to be loose. Three patients had revision surgery. In two of the three cases, the implants were found to be firmly fixed. There was no clinical or bacteriologic evidence of infection. The polyethylene articulating surface showed signs of wear in all three cases and in one of the three it dislocated from the metal shell. Granulation tissue was found in the regions of osteolysis, and the diseased tissue contained numerous macrophages and giant cells. Lymphocytes and plasma cells were rare. Numerous small particles of phagocytosed polyethylene and metal in the cells were noted in two cases, whereas only polyethylene was found in the third.(ABSTRACT TRUNCATED AT 250 WORDS)