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.

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.

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).

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.

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.

Isolation and quantitation of debris particles around failed silicone orthopedic implants.

Silicone elastomer implants have a relatively low rate of complications, but inflammatory reactions to debris have been reported. To characterize the size and number of debris particles, we isolated and quantified the debris particles present in the periarticular tissues of 10 patients with failed silicone wrist, elbow, or finger implants. Five rheumatoid synovia without implants were used for negative controls. The number of particles ranged from 0.99 to 24.8 x 10(9) per gram (dry weight) of tissue, and nearly all particles were silicone, as determined by x-ray spectroscopy. The implantation duration ranged from 3.2 to 10.6 years, and for the five wrist implants, the number of particles correlated with duration in vivo. The particles were small (mode particle diameter was 0.59 +/- 0.057 micron). These results suggest that billions of particles, most of which are smaller than 1 micron, are present adjacent to failed silicone implants, and may be associated with inflammation and bone resorption.

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.

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.

Management of infected knee and hip prostheses.

The number of total hip and knee replacements that are performed is growing, resulting in an increased number of procedures undertaken to remove replacements that become infected. The treatment of infected replacements is expensive, creating a strong incentive to avoid infection. Preventive measures such as preoperative intravenous antibiotics and double-latex gloves are useful in this respect. When infection occurs in a knee or hip replacement, various procedures are used. Antibiotic suppression is used when the patient is a poor risk for surgery. Debridement of the knee and administration of intravenous antibiotics is appropriate when infection is diagnosed within 2 weeks of onset. Resection arthroplasty is reserved for large knee implants, such as hinges, in patients with limited functional capacity. Arthrodesis of the knee is undertaken in the young patient with single-joint disease, when two-stage reimplantation fails, or when there are multiple problems such as skin loss, massive bone loss, and virulent organisms. When infection cannot be controlled by any other means, amputation is indicated. For infected hip replacements, debridement of the hip with retention of the prosthesis is often successful. Two-stage reimplantation for the treatment of infected total hip prostheses is more successful than one-stage reimplantation. Arthrodesis of the hip after removal of an infected total hip prosthesis can leave the leg 2 to 3 inches short. The diagnosis and treatment of infected knee and hip replacements is reviewed in detail below.

Management of infected knee and hip prostheses.

Infection following total hip or total knee arthroplasty can be devastating. It can result in instability of the hip or knee, diminished function, amputation, or death. Fulminant infection is unusual. Chronic low-grade infection is more commonly seen clinically. Differentiation of pain in a total hip or total knee replacement from loosening or infection may be difficult. Aspiration of the hip or knee for three aerobic and anaerobic cultures and sensitivities is the most reliable method of diagnosing infection. In the hip joint, aspiration should be performed under radiographic control. Treatment of the infected total hip or total knee by antibiotics alone is ineffective. Debridement of the hip or knee joint with retention of the prosthesis and intravenous antibiotics is successful in 18% to 40% of cases. Resection arthroplasty of the hip or knee usually results in eradication of the infection but leaves a painful, unstable, and shortened extremity and diminished ability to ambulate. Arthrodesis of the knee usually clears the infection but imposes the disability of a stiff knee. Two-stage reimplantation of the hip or knee is the most successful means of treating the infected total hip or knee replacement. In the knee, the success rate with two-stage reimplantation is 80% to 97%. In the hip joint, the success rate of two-stage reimplantation is 83% to 87%. Recently, debridement of the hip or knee with retention of the prosthesis and the local installation of antibiotics for a prolonged period has been used in cases of acute infection of less than 3 months' duration without evidence of implant loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

A cost-benefit analysis for materials management information systems.

The cost-benefit analysis provided the system planners with valuable information that served many purposes. It answered the following questions: Why was the CCF undertaking this project? What were the alternatives? How much was it going to cost? And what was the expected outcome? The process of developing cost-benefit the document kept the project team focused. It also motivated them to involve additional individuals from materials management and accounts payable in its development. A byproduct of this involvement was buy-in and commitment to the project by everyone in these areas. Consequently, the project became a team effort championed by many and not just one. We were also able to introduce two new information system processes: 1) a management review process with goals and anticipated results, and 2) a quality assurance process that ensured the CCF had a better product in the end. The cost-benefit analysis provided a planning tool that assisted in successful implementation of an integrated materials management information system.

Long-term follow-up of the Conaxial (Beck-Steffee) total ankle arthroplasty.

Between 1975 and 1977, 30 patients with traumatic arthritis or rheumatoid arthritis underwent 36 Conaxial (Beck-Steffee) ankle replacements (DePuy, Warsaw, IN). Thirty-two were primary replacements and four were revisions of previous ankle arthroplasties. Twelve patients had traumatic osteoarthritis and 18 patients had rheumatoid arthritis. The average age at operation of patients with rheumatoid arthritis was 61 years (range 28-67 years) and with osteoarthritis was 52.9 years (range 32-72 years). The average follow-up was 10.8 years, with a range of 10 to 13 years. Early postoperative complications included wound dehiscence in 39% of patients (14 patients), deep wound infection in 6%, fractures of the medial or lateral malleolus in 22%, and painful talofibular impingement in 14%. At 2-year follow-up, 27% of the ankle replacements were loose. Sixty percent were loose at 5 years and 90% were loose at the 10-year follow-up. Ten patients had implant removal and attempted fusion. Six, or 60%, fused in an average of 5 months. Of those patients who achieved ankle fusion, four had internal fixation and iliac crest autografting, one had a Charnley compression apparatus with allograft bone, and one had internal fixation with allograft bone. The constrained Conaxial ankle replacement should no longer be implanted because of a 90% loosening rate at 10 years and an overall complication rate of 60%.

Capitellocondylar total elbow replacement. A long-term follow-up study.

Fifty-one capitellocondylar elbow replacements were inserted in forty-one patients between 1976 and 1986. Thirty-nine patients had rheumatoid arthritis and two had traumatic osteoarthrosis. The average age of the patients at the time of the operation was fifty-six years (range, twenty-one to seventy-seven years). Thirty-one patients who had thirty-nine retained elbow prostheses had an average length of follow-up of 6.5 years (range, two to thirteen years). Flexion improved an average of 20 degrees; extension, 4 degrees; pronation, 22 degrees; and supination, 36 degrees. Relief of pain was complete in 85 per cent of the thirty-nine elbows, and in 15 per cent there was only mild pain. Noteworthy postoperative complications in the original fifty-one elbows included infection in four elbows (8 per cent), dislocation in three (6 per cent), and ulnar neuropathy in sixteen (31 per cent). Three elbows were revised: one for a humeral fracture, one for recurrent dislocation, and one for aseptic loosening. Aseptic loosening was evident on radiographs of two elbows; one patient was completely asymptomatic, and one had mild pain with deformity. The Souter zonal radiographic assessment system for identification of radiolucencies at the bone-cement interface was utilized; there was no significant difference in radiolucencies between ulnar components backed with metal and those that were not backed with metal. Kaplan-Meier cumulative survivorship analysis demonstrated that a functional prosthesis was retained in 88 per cent of the elbows at 1.4 years postoperatively and in 83 per cent at 5.5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

The incorporation of tibial allografts in total knee arthroplasty.

Twelve knees in ten patients had revision total knee replacement with insertion of an allograft for a large tibial defect. The knees were retrospectively evaluated at an average of thirty-two months (range, twenty-five to fifty-one months) by clinical examination, radiography, planar bone scintigraphy, and single-photon-emission computed tomography. The average age of the patients was sixty-two years (range, fifty-four to seventy-nine years). A constrained total-condylar prosthesis was used for all revisions. A contained tibial defect was present in five knees, and seven knees had an uncontained defect that was treated with a massive composite structural allograft, five of which were secured with internal fixation. The knee scores improved from an average of 51 points before operation to an average of 87 points post-operatively. Seven knees had a score of 85 points or more and were considered to have an excellent clinical result. Two knees had a good result, with scores of 77 and 72 points. One knee had another revision because of painful non-union of a medial structural graft, and the result in that knee was considered a failure. The average range of motion improved from 84 degrees to 105 degrees. There were no deep infections, and no graft showed evidence of fracture or collapse. Radiographs demonstrated complete incorporation of the graft in eleven of the twelve knees at an average of twenty-three months after operation. Single-photon-emission computed-tomography scans showed uniform activity in the area of the graft in four of the five knees that were studied.

Intramedullary fixation for arthrodesis of the knee after infected total knee arthroplasty.

Knee arthrodesis with curved intramedullary rods was performed in 12 patients after infected total knee arthroplasty. The underlying pathologic condition was osteoarthritis in nine patients and rheumatoid arthritis in three patients. Nine patients with a postoperative follow-up time of greater than two years (average, 34 months; median, 29 months; longest, 55 months) were evaluated for functional results. Six patients obtained a satisfactory knee fusion in an average of 6.6 months (range, three to 11 months; median, five months). Those patients without massive bone loss preoperatively attained a fusion rate of 66.6%. Two thirds of the patients with massive bone loss attained fusion. Indications for surgery in addition to infection included massive bone loss, mixed infection with multiple organisms, infrapatellar tendon rupture, ligamentous instability, and severe valgus deformity with tibial fracture nonunion. Failure occurred in three cases. One was associated with rod breakage; another was due to massive bone resorption; and the third was in a diabetic female with infrapatellar tendon rupture. All patients with successful arthrodesis reported an absence of pain and the ability to ambulate with, at most, a walker. The use of curved intramedullary rods is a convenient technique for obtaining successful arthrodesis after infected total knee arthroplasty.

Two-stage reimplantation in infected total knee arthroplasty.

Twenty-one infected total knee arthroplasties (TKA) in 21 patients were treated from September 1980 through October 1987. Of these, 15 were followed for more than one year. Treatment of these patients consisted of thorough debridement of all infected tissue and components; a cement spacer was used in ten patients. The cement was impregnated with antibiotics. This procedure was followed for an average of 4.2 weeks with intravenous antibiotics and TKA utilizing antibiotic-impregnated cement. Five patients had rheumatoid arthritis and ten had osteoarthritis. The organisms included Staphylococcus coagulase negative (seven patients), Streptococcus group B (two patients), Streptococcus bovis (one patient), Enterococcus (one patient), Staphylococcus coagulase positive and Bacillus circulans (one patient), Staphylococcus coagulase negative and Enterococcus (one patient), Staphylococcus coagulase negative and Pseudomonas aeuriginosa (one patient), and Clostridium perfringens (one patient). Of the 15 patients, 12 appeared to be free of infection, two were obvious failures and required knee fusion, and one was suspected of having continued infection at five years and was treated elsewhere. Eleven patients with revision TKA were available for follow-up examinations at an average of 2.9 years (range, one to six years). One patient died five years after reimplantation but had been functioning well. One patient functioning at three years postreimplantation did not return for a later follow-up examination. The average knee score (modification of the Hospital for Special Surgery Knee Score) was 75.5 points (range, 48-94); average flexion was 81 degrees (range, 52 degrees-120 degrees), and average extension was +6 degrees (range, 0 degrees-30 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)