Hip implant infection. Treatment with resection arthroplasty and late total hip arthroplasty.

In 131 patients with an infected hip implant, treatment was surgical excision of the implant (resection arthroplasty) and delayed reconstruction with a total hip arthroplasty. Most of the patients had low-grade infections: only 5 percent had a temperature of 37.8 degrees C or higher and only 20 percent had wound drainage. Hip pain was the primary symptom of a deep infection in 90 percent. Staphylococci were the most frequently isolated causal organisms, recovered from deep tissue specimens in 84 patients. The hip was reconstructed six days to 32 years (mode, 429 days) after resection arthroplasty. At follow-up two to nine years after reconstruction, 88 percent of the 131 patients were free of infection. Recurrent sepsis was more common (p less than 0.05) in patients with incomplete acrylic cement removal or patients in whom reconstruction was performed less than 429 days after resection arthroplasty. Risk of recurrent sepsis was increased when gram-negative bacilli in pure or mixed cultures were found, but the difference was not statistically significant.

Sequential technetium-99m HMDP-gallium-67 citrate imaging for the evaluation of infection in the painful prosthesis.

In order to evaluate the clinical utility of sequential technetium-99m HMDP-gallium-67 scanning in patients with painful orthopedic prosthesis, a retrospective review was made of 154 sequential scans performed in 130 patients. Criteria for a positive study included spatially incongruent gallium-technetium uptake or gallium uptake that was congruent but more intense than technetium. Images were interpreted as negative if gallium was congruent and less intense than technetium. Sixty-six patients underwent surgery (31 infected, 35 aseptic), and 64 were evaluated clinically (3 infected, 61 aseptic). The combined results of the surgical and nonsurgical patients yielded a sensitivity of 66%, a specificity of 81%, and an accuracy of 77%. In this series, the technetium-gallium scan combination has proven to be helpful but more recent techniques such as indium-111-labeled leukocytes may prove to be superior to sequential technetium-gallium imaging.

The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants.

UNLABELLED: The purpose of this study was to evaluate the feasibility of using 18F-FDG and PET for the detection of infection associated with lower limb arthroplasty. METHODS: Seventy-four prostheses in 62 patients in whom infection was suspected after artificial hip or knee placement were studied with this technique. Images were obtained 60 min after an intravenous injection of FDG. The images were interpreted as positive for infection if tracer uptake was increased at the bone-prosthesis interface. A final diagnosis was made by surgical exploration or clinical follow-up for 1 y. PET results were compared with the follow-up outcome in all patients. RESULTS: The sensitivity, specificity, and accuracy of PET for detecting infection associated with knee prostheses were 90.9%, 72.0%, and 77.8%, respectively. The sensitivity, specificity, and accuracy of PET for detecting infection associated with hip prostheses were 90%, 89.3%, and 89.5%, respectively. Overall, the sensitivity was 90.5% and the specificity was 81.1% for detection of lower limb infections. CONCLUSION: FDG PET is a useful imaging modality for detecting infections associated with lower limb arthroplasty and is more accurate for detecting infections associated with hip prostheses than for detecting infections associated with knee prostheses.

Intrasynovial injection of steroids uses and abuses.

Intra-articular injection of steroids is a valuable method of treatment, but selection of the appropriate clinical setting is required to obtain maximal benefits and to minimize the complications. All intra-articular injections must be performed under strict aseptic technique. The rheumatoid patient with one or two joints that resist systemic therapy and the patient with an occasional osteoarthritic joint with an acute inflammation are amenable to this treatment. The patient who has acute attacks of tendinitis, pseudogout, or bursitis will obtain significant benefits. Selected patients with traumatic and acute gouty arthritis also may benefit. Repetitive injections appear to be contra-indicated as they may create an environment conducive to joint destruction.

Total joint arthroplasty. Biologic causes of failure.

Hypersensitivity reactions and deep sepsis are the primary forms of biologic failure of total joint arthroplasty. Hypersensitivity reactions appear to be related to metal debris associated with metal articulating with metal arthroplasties. Although the incidence of deep sepsis following total joint arthroplasty is lower than initially feared, it remains a serious problem for both the patient and the surgeon. Fixation of prosthetic devices with methyl methacrylate appears safe. However, improved methods of fixation which are more compatible with osseous tissue are currently under study. The advantages of porous materials and the results of laboratory studies are reviewed.

Total joint arthroplasty. The knee.

Total knee replacement has become an established form of treatment for gonarthrosis and usually results in excellent relief of pain and approximately 90 degrees of joint motion with satisfactory joint stability. The anatomic stability that cannot be restored at surgery must be provided for by additional prosthetic stability. Fixation of prosthetic devices, particularly in the tibia, is marginal and results in an increased incidence of loosening when the quality of bone is weak, as in osteoporosis, or when shear stress is increased because of malalignment or prosthetic constraint. Resurfacing techniques provide the greatest options if surgical revision is necessary. Surgical goals should be realistically assessed so as to maintain the best potential for future treatment options.

Symposium on arthritis in older persons. Section II. Drugs and intrasynovial steroid therapy. Intrasynovial steroid therapy: uses and abuses. (Summary of presentation).

The indications and contraindications for use of intrasynovial steroid therapy are discussed. When properly used, the intrasynovial injection of steroids is a valuable method of treatment.

Symposium on arthritis in older persons. Section IV. Surgery and rehabilitation. Total joint replacement: lower extremities (Summary of presentation).

In experience with total joint replacement in the lower extremity, to date, total hip arthroplasty has been the most successful. Total arthroplasty operations as applied to the knee and ankle are giving promising results. These methods offer new avenues for relief of pain and deformity and stabilization of arthritic joints in the lower extremity.

Microbiologic environment of the conventional operating room.

Areas of potential contamination of the surgical wound in the conventional operating rooms include the back table, the unsterile suction receptacle, and the lack of a positive pressure relationship between the operating room and adjacent areas. Use of an impermeable hood with a large mask diminished contamination of the instrument table and the the wound from fallout of bacteria from the surgical team. The level of airborne bacterial comtamination in the operating room can be reduced by limiting the traffic and controlling the activity and the number of operating room personnel. Higher rates of postoperatively wound sepsis were noted in older operating rooms, particularly with difficult procedures and those performed later in the day. Conventional operating rooms should be categorized by the level of room air exchange per hour and the level of airborne bacterial contamination.

Infections of hip prostheses and artificial joints.

Infections following total joint arthroplasty have been dramatically lowered with the administration of prophylactic antibiotics. Anecdotal experience as well as prospective data suggests that ultra-clean operating rooms can further reduce the incidence of postoperative wound sepsis following total joint arthroplasty. Once a deep infection complicates a total joint arthroplasty, resection arthroplasty will usually be necessary. Staphylococci are the most common causal organisms. Four weeks of specific, parenteral therapy should be administered at the time of the resection arthroplasty. Reconstruction with another total joint can be performed in a "one-staged" or a delayed fashion. The decision as to which procedure should be performed is made based on the degree of virulence of the infection (microbiology) and the anatomic location. Successful reconstruction can be achieved in 95 per cent of carefully selected patients.

Reduction of deep sepsis after total hip arthroplasty.

The role of the operating room environment in the development of deep sepsis after total hip arthroplasty was studied at four centers. The incidence of deep sepsis after 5,865 total hip arthroplasties performed in the four centers varied from 0.5% to 2.3%. Procedures performed in a conventional operating room were associated with the highest incidence of deep sepsis (1.3%). The use of a vertical, unidrectional airflow system with a helmet aspirator suite was associated with the lowest incidence of deep sepsis (0.6%). Although patients with previous hip surgery had an increased incidence of deep sepsis regardless of the operating room environment, those procedures performed in a vertical, unidrectional facility had a lower incidence of deep sepsis. Newer techniques designed for the reduction of airborne contamination of the operative wound seem to reduce the incidence of deep-wound sepsis after total hip arthroplasty, especially in patients with previous hip surgery.

Bypassing femoral cortical defects with cemented intramedullary stems.

The objective of this investigation was to examine the effect of cemented intramedullary stem bypass on bone torsional property in the presence of femoral cortical defect. We intended to test two hypotheses; first, intramedullary fixation without bypass will accentuate the stress concentration effect and second, there will be an optimal length of stem bypass beyond the defect. Cemented intramedullary stems were used to bypass 50% diaphyseal diameter unicortical defects in paired, fresh-frozen canine femora. One member of each pair served as an unaltered control and all specimens were tested to failure in torsion. Both single-tailed paired t-test and analysis of variance were used for data analysis. Bones subjected to the cortical defect and no bypass were substantially weakened, exhibiting only 44 +/- 8% of control side maximum torque (p less than 0.001). Positioning of the intramedullary stem with its tip at the center of the defect provided a small degree of strength improvement, achieving 60 +/- 7% of control side maximum torque. One and two diaphyseal diameter bypass, however, significantly (p less than 0.01) improved bone torsional strength, resulting in 80 +/- 6% and 84 +/- 13% of control side maximum torque, respectively. Three diameter bypass achieved only 68 +/- 8% of control side maximum torque. This significant (p less than 0.05) decline in strength when compared to two diameter bypass appears to indicate that the length of stem bypass beyond the cortical defect does have an optimum, probably due to the geometric characteristics of the canine femora.

Dynamic radioisotope bone imaging as a noninvasive indicator of canine tibial blood flow.

The relative values of dynamic and static bone imaging with hydroxymethylenediphosphonate technetium 99m (99mTc HDP) as an indicator of bone blood flow was investigated in the tibia of mature dogs. The dynamic bone scan consisted of 60 1-s images formed after the intravenous injection of 99mTc HDP, and the static bone scan was a 45-min uptake image. Blood flow to the tibia was determined by using radioactively labeled microspheres. Studies were carried out in control dogs, in dogs in which blood flow was increased in one leg with ATP, and in dogs in which blood flow was decreased in one leg with norepinephrine. A significant (p less than 0.001) linear relationship between the dynamic scan values and bone blood flow was found at a wide range of blood flow rates. When blood flow increased by more than 50%, the effects of "diffusion limitation" were seen in the static scans: increase in tracer uptake was disproportionately small for a significant increase in blood flow. There is no method currently available for estimating bone blood flow by a noninvasive technique. The method described here may be useful for providing a semiquantitative measure of bone blood flow. This improved versatility of bone imaging may have a role in the management of osteomyelitis or complicated fractures, or in assessing the viability of vascularized bone grafts.

Experimental acute hematogenous osteomyelitis in mice. I. Histopathological and immunological findings.

This study investigated immunological responses to Staphylococcus aureus bone infection. Because considerable immunological information is available on the mouse, a murine model of acute hematogenous osteomyelitis was established. Osteomyelitis was created in the proximal tibia of C3H/HeJ mice by a tibial epiphyseal fracture followed by intravenous bacterial inoculation with Staphylococcus aureus (strain LS-1). Swelling and warmth of the limb was found, and following limb exposure, abscess formation was evident in the proximal tibia. Histological examination revealed distortion primarily at the hypertrophic zone of the physis and polymorphonuclear leukocyte infiltration throughout the damaged area of the proximal tibia. Local infection was demonstrated at the fracture site, evidenced by the recovery of Staphylococcus aureus following microbiological analysis of tissue specimens. Polymerase chain reaction was utilized to detect 16S ribosomal prokaryotic nucleic acid to demonstrate that the diagnosis of osteomyelitis could be established in the absence of conventional microbiological techniques. The infected mice had an increase of circulating large leukocytes (granulocytes) and an elevation of total serum immunoglobulin. Flow cytometry revealed significant increases in splenic B lymphocytes and in lymph-node CD4+ T lymphocytes. These results indicate that an experimental model of acute hematogenous osteomyelitis that closely resembles the pathology of the disease in humans may be consistently induced in mice. Furthermore, marked immunological changes may be observed in response to the Staphylococcus aureus bone infection.

Experimental acute hematogenous osteomyelitis in mice. II. Influence of Staphylococcus aureus infection on T-cell immunity.

A murine model of acute hematogenous osteomyelitis was used to study the immune response following Staphylococcus aureus infection and to examine the hypothesis that the bacteria may modify T-cell responses due to the production of bacterial enterotoxins with mitogenic or superantigenic activity. Lymph-node T cell-receptor expression was assessed with use of flow cytometry and reverse transcription-polymerase chain reaction techniques, and increased apoptosis (programmed cell death) in T-cell subsets was monitored. The expression and levels of circulating cytokines and T-cell cytokines within tissues surrounding the damaged area of the proximal tibia were also investigated. Analysis of T-cell receptors in experimental osteomyelitis revealed two distinct patterns of T-cell evolution during the disease. Certain T-cell subsets (Vbeta2, Vbeta3, Vbeta9, and Vbeta10) were activated and expanded during the first 24 hours after infection; they reached maximum levels 6 days after infection, followed by a return to pre-infection levels. In contrast, other T-cell subsets (Vbeta11, Vbeta12, Vbeta13, Vbeta14, and Vbeta16) contracted during the first 24 hours after infection, followed by expansion to a maximum level 9 days after infection. Activation and proliferation of T-cell subsets (notably Vbeta14 T cells) was followed by apoptosis, suggesting that staphylococcal bone infection caused superantigenic-like effects on the mouse immune system. Analysis of cytokine responses in local tissue revealed that the T-cell cytokines interleukin-2 and interferon-gamma showed a late and relatively short activation pattern compared with the inflammatory cytokines interleukin-1, interleukin-6, and tumor necrosis factor-alpha. The results suggest that Staphylococcus aureus bone infection may undermine the antibacterial immune response through downregulation of T-cell immunity and immune-cytokine production, which could increase the severity of the systemic infection and local osseous destruction that occur with acute hematogenous osteomyelitis.

Experimental osteomyelitis: description of a canine model and the role of depot administration of antibiotics in the prevention and treatment of sepsis.

UNLABELLED: Osteomyelitis of the proximal portion of the tibia was consistently produced in the dog by the instillation of a suspension of Staphylococcus aureus about an intramedullary foreign body consisting of acrylic bone cement. The clinical, histological, and roentgenographic manifestations of the infectious process were consistent with those of subacute osteomyelitis, such as may be encountered in infections following total joint arthroplasty. The osteomyelitic process persisted in six of the seven tibiae even after removal of the acrylic bone cement. Using this model, gentamicin-impregnated acrylic bone cement (Palacos) prevented the development of osteomyelitis in nine of ten tibiae that were concomitantly exposed to Staphylococcus aureus in concentrations ranging from 1 x 10(3) to 1 x 10(9) organisms. However, Palacos in bulk form was ineffective in the treatment of three of five tibiae in which osteomyelitis caused by Staphylococcus aureus was already established. CLINICAL RELEVANCE: A variety of new antimicrobial agents has been introduced, but evaluation of the value of these agents in infections of the musculoskeletal system has relied almost exclusively on clinical trials. Preclinical trials in an animal model could permit earlier detection of promising agents and proper dosage schedules. Newer surgical procedures utilized in the treatment of osteomyelitis, such as local muscle flaps and free vascularized flaps, could also be evaluated to determine how they influence the local blood supply and microbial persistence. In addition, the animal model might aid in the evaluation of newer and non-invasive diagnostic scanning techniques used in the study of infection.

Total hip arthroplasty in the ankylosed hip. A ten-year follow-up.

Eighty total hip arthroplasties in seventy-four patients who had had either a spontaneous or a surgical ankylosis (arthrodesis) of the hip were evaluated at nine to fifteen years (average, 10.4 years) after the total hip replacement. There was only one failure in the twenty hips of the fifteen patients who had had a spontaneous ankylosis. In contrast, twenty (33 per cent) of the sixty hips of the sixty patients who had had a surgical ankylosis had complications that were associated with the arthroplasty. Of these twenty hips, mechanical loosening developed in eleven; infection, in eight; and recurring dislocation, in one. Failure of the total hip arthroplasty was more common (p less than 0.05) in the patients who had had a previous surgical attempt at arthrodesis and in the patients who were fifty years old or less at the time of the arthroplasty. The risk of failure was not related to the length of time that the hip had been ankylosed.

Hinged total knee arthroplasty.

Analysis of an on-going prospective study of seventy-seven hinged total knee arthroplasties in sixty-seven patients revealed that most patients had improvement in function, although major complications occurred in eighteen knees (23.4 per cent. These complications included sepsis, loosening, patellar tendon rupture, peroneal palsy, and patellar subluxation. Eight of nine knees with deep sepsis required removal of the prosthesis, and three of sixteen knees with patellar pain required realignment of the quadriceps. When prosthetic failure occurred, salvage of a functional extremity was difficult. Hinged total arthroplasty is not without its problems, and a cautious approach to its use is indicated. Whenever possible, a moderately constrained replacement arthroplasty should be considered.

Multiple revisions for failed total hip arthroplasty not associated with infection.

Forty-five patients (forty-five hips) underwent repeat revisions of a total hip arthroplasty that had failed but was not associated with infection; seven of these patients had a third revision. The mean length of follow-up was approximately three years, and no patients were lost to follow-up. Twenty-eight of the forty-five patients had no or slight pain after the second revision, and thirty reported that their condition was improved. After the third revision, six patients had no or only slight pain, and five said that their condition was improved. On final roentgenographic examination, there was probable loosening (migration or subsidence of a component, lucency at the prosthesis-cement interface, fracture of the cement, or complete radiolucency at the bone-cement, or complete radiolucency at the bone-cement interface of more than one millimeter in at least one zone) of eight of the acetabular components and thirteen of the femoral components after the second revision and three acetabular components and one femoral component after the third. There was symptomatic loosening (moderate or severe pain and probable roentgenographic loosening) in six patients after the second revision and one after the third. Significant postoperative complications were noted in nineteen of the forty-five patients, and treatment was considered to be a failure in eleven hips after the second revision and in two after the third.

A histological study of acute hematogenous osteomyelitis following physeal injuries in rabbits.

In young rabbits, the effects of an intravenous injection of Staphylococcus aureus alone, and in combination with a traumatic injury of the proximal tibial physis, were studied by light and electron microscopy. Metaphyseal osteomyelitis and radiographic changes were seen within forty-eight hours after the injury in all rabbits that had a growth-plate disruption and bacteremia. An intravenous injection of bacteria alone produced no morphological or microbiological evidence of infection. In the absence of trauma, normal tibiae were sterile after forty-eight hours. Foreign-body particles have been shown to accumulate in the fine vessels that are adjacent to the growth plate, but we found no similar deposition of bacteria or evidence of phagocytic removal in this area. Phagocytosis of bacteria by neutrophils did not appear to be impaired in the distal third of the metaphysis, but a delayed inflammatory response that allowed proliferation of bacteria and destruction of tissue was observed in the proximal two-thirds of the metaphysis after trauma.