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Local environment surrounding Zr atoms in the thin films of nanocrystalline zirconia (ZrO2) has been investigated by using the extended x-ray absorption fine structure (EXAFS) technique. These films prepared by the ion beam assisted deposition exhibit long-range structural order of cubic phase and high hardness at room temperature without chemical stabilizers. The local structure around Zr probed by EXAFS indicates a cubic Zr sublattice with O atoms located on the nearest tetragonal sites with respect to the Zr central atoms, as well as highly disordered locations. Similar Zr local structure was also found in a ZrO2 nanocrystal sample prepared by a sol-gel method. Variations in local structures due to thermal annealing were observed and analyzed. Most importantly, our x-ray results provide direct experimental evidence for the existence of oxygen vacancies arising from local disorder and distortion of the oxygen sublattice in nanocrystalline ZrO2. These oxygen vacancies are regarded as the essential stabilizing factor for the nanostructurally stabilized cubic zirconia. [ABSTRACT FROM AUTHOR]

Background: Polyethylene wear debris, and the resulting inflammatory response leading to osteolysis and loosening, is the primary mode of failure limiting the longevity of total hip replacements. Alternative bearing surfaces, including ceramic-on-polyethylene, have been investigated in an effort to decrease the amount of polyethylene wear debris. The purpose of this study was to evaluate the seventeen to twenty-one-year results of the use of ceramic-on-polyethylene total hip prostheses.Methods: Sixty-four total hip prostheses were implanted with cement, by one surgeon, in fifty-six patients from 1978 to 1981. The average age at the index arthroplasty was sixty-nine years (range, fifty-one to eighty-four years). The components consisted of a cemented Charnley-Müller stem with a 32-mm modular alumina femoral head and a cemented all-polyethylene acetabular component. All patients who retained the index prosthesis were assessed clinically with use of Harris hip scores and were evaluated radiographically at the time of the latest follow-up.Results: At the time of this latest follow-up, of the original sixty-four implants, eighteen (28%) were still in place and five (8%) had been revised. The remaining forty-one implants were in patients who had died and were functioning well until the patient's death. No patient was lost to follow-up. Of the eighteen hips with an intact prosthesis in the surviving patients, seven had an excellent clinical result; nine, a good result; and two, a fair result. One asymptomatic hip had definite radiographic evidence of femoral loosening. No hip had definite signs of acetabular loosening or evidence of osteolysis. Survivorship analysis revealed that the probability of survival of the prostheses without revision was 95% at five years, 95% at ten years, 89% at fifteen years, and 79% at twenty years. The mean linear and volumetric polyethylene wear rates were 0.034 mm/yr and 28 mm(3)/yr, respectively. There were no fractures of the ceramic heads.Conclusions: Outstanding long-term clinical and radiographic results were attained despite the use of what are now considered substandard techniques (an inferior stem design, a 32-mm head, and first-generation cementing techniques). The wear rates in this study are lower than previously reported metal-on-polyethylene wear rates and are consistent with the lowest reported in vivo ceramic-on-polyethylene wear rates. These findings support the consideration of ceramic-on-polyethylene bearing surfaces in total hip arthroplasty. [ABSTRACT FROM AUTHOR]

Background: While autologous blood is commonly predonated to provide replacement of blood lost in orthopaedic procedures, few studies of patients managed with total joint replacement have addressed the problem of which patients are likely to benefit from an autologous blood-donation program.Methods: A retrospective analysis of 489 consecutive patients who had had a total joint arthroplasty was performed to identify the risk factors for allogenic transfusion and to further define the indications for preoperative autologous blood donation. The operations included 247 total knee replacements (157 unilateral primary, thirty-two revision, and twenty-nine one-stage bilateral primary procedures) and 271 total hip replacements (163 primary and 108 revision procedures). Fifty-four percent (264) of the 489 patients donated a total of 527 units of blood (average, 2.0 units per patient) preoperatively.Results: One hundred and ninety-one patients (39 percent) required a transfusion of autologous blood or allogenic blood, or both. One hundred and thirty-one patients (27 percent) received autologous blood, and eighty-two patients (17 percent) received a transfusion of allogenic blood; twenty-two patients (4 percent) received both autologous and allogenic blood. Neither form of transfusion caused serious complications. Fifty-six percent (295) of the 527 units of autologous blood were discarded. Autologous donation significantly decreased the requirements for allogenic transfusion (relative risk, 0.1; p<0.0001). It also caused the level of hemoglobin to decrease an average of 12.2 grams per liter from the time before donation to the time before the operation (p<0.0001). Factors that increased the risk for allogenic transfusion were a revision knee or hip procedure or a one-stage bilateral primary knee replacement (relative risk, 5.7; p<0.0001), an initial hemoglobin level of less than 130 grams per liter (relative risk, 5.6; p<0.0001), and an age of sixty-five years or older (relative risk, 2.8; p = 0.02). None of the sixty-seven patients who had a primary knee or hip arthroplasty and an initial hemoglobin level of 150 grams per liter or more required an allogenic transfusion. In addition, none of the sixty-three patients who had a primary arthroplasty, an initial hemoglobin level of between 130 and less than 150 grams per liter, and an age of less than sixty-five years required an allogenic transfusion. Eighty-three percent (115) of the 138 autologous units donated by the seventy patients in these two groups were discarded. These wasted units accounted for 39 percent of the 295 discarded units for the entire study sample.Conclusions: The efficiency of collection of autologous blood can be improved by identifying patients who have a very low risk of transfusion according to the type of arthroplasty, the initial level of hemoglobin, and age. Patients who have an initial hemoglobin level of at least 150 grams per liter or an initial hemoglobin level of between 130 and 150 grams per liter and an age of less than sixty-five years have a minimal risk of needing a transfusion during or after a primary total joint replacement. These patients should be apprised of their low risk so that they can make an informed decision regarding preoperative autologous donation. [ABSTRACT FROM AUTHOR]

A titanium Greenfield filter did not open following placement in the infrarenal inferior vena cava (IVC). Abdominal radiograph and cavogram showed no definite reason for filter malfunction. Intravascular ultrasound (IVUS) demonstrated the unopened filter in the IVC with thrombus binding the legs. The thrombus was disrupted with a catheter, and the filter completely expanded with a balloon. IVUS documented full-filter opening in addition to residual thrombus in the filter following manipulation. [ABSTRACT FROM AUTHOR]

Hematological deficiencies increase with aging leading to anemias, reduced hematopoietic stress responses and myelodysplasias. This study tested the hypothesis that side population hematopoietic stem cells (SP-HSC) would decrease with aging, correlating with IGF-1 and IL-6 levels and increases in bone marrow fat. Marrow was obtained from the femoral head and trochanteric region of the femur at surgery for total hip replacement (N=100). Whole trabecular marrow samples were ground in a sterile mortar and pestle and cellularity and fat content determined. Marrow and blood mononuclear cells were stained with Hoechst dye and the SP-HSC profiles acquired. Marrow stromal cells (MSC) were enumerated flow cytometrically employing the Stro-1 antibody, and clonally in the colony forming unit fibroblast (CFU-F) assay. Plasma levels of IGF-1 (ng/ml) and IL-6 (pg/ml) were measured by ELISA. SP-HSC in blood and bone marrow decreased with age but the quality of the surviving stem cells increased. MSC decreased non-significantly. IGF-1 levels (mean=30.7, SEM=2) decreased and IL-6 levels (mean=4.4, SEM=1) increased with age as did marrow fat (mean=1.2mmfat/g, SEM=0.04). There were no significant correlations between cytokine levels or fat and SP-HSC numbers. Stem cells appear to be progressively lost with aging and only the highest quality stem cells survive., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Experimental models were created in rat fibula to represent impaired bone healing so that biological deficiencies that cause bone repair to fail or to be delayed may be investigated. These models consist of a 4-mm-long segmental defect, created in rat fibula by osteotomy, and fitted with a 7-mm-long tubular specimen of demineralized bone matrix (DBM) over the cut ends of the fibula. The experiments in this study involved various modifications of the DBM scaffold designed to reduce its osteoinductive activity: steam sterilization (sDBM), ethylene oxide sterilization (eoDBM), trypsin digestion (tDBM), and guanidine hydrochloride extraction (gDBM). Bone healing was evaluated by bending rigidity of the fibula and mineral content of the repair site at 7 weeks post-surgery. The sDBM scaffolds resorbed completely by 7 weeks and hence this model was a nonhealing negative control. Rigidities in the unmodified DBM and tDBM groups were comparable, whereas in the gDBM and eoDBM groups it was significantly reduced. Histologically, in the 4-mm defects repaired with unmodified DBM, direct and endochondral bone formation in the scaffold and the defect resulted in a neocortex consisting of woven and lamellar bone uniting the broken bone by 7 weeks post-surgery. We conclude that the eoDBM and gDBM groups represent failure or delay of the bone repair process when compared with the unmodified DBM group in which the process is analogous to normal bone healing.

The current success in treatment of surgical site infections may be jeopardized by the continued emergence of antibiotic resistance in bacteria common to these infections. The effectiveness of vancomycin against methicillin-resistant staphylococci may decrease as more cases of VISA emerge. No currently available antimicrobial is consistently effective against certain strains of VRE and the potential emergence of VRSA. Orthopaedic surgeons soon may be in the undesirable position of having to eradicate organisms resistant to all available antibiotics. Several new antibiotics show promising activity and may be useful against these multidrug-resistant bacteria. However, as the history of bacterial resistance has taught us, it likely only will be a matter of time until these organisms adapt mechanisms of resistance to these new drugs. The key then lies, as it always has, in preventive measures. Surgeons, and all physicians, must adhere to the precautionary guidelines recently set forth by the CDC and HICPAC. Chief among these guidelines is the elimination of inappropriate antibiotic usage, especially inappropriate vancomycin use.

Successful treatment of an infected total joint arthroplasty can be achieved in approximately 90% of cases. This outcome may be jeopardized by the emergence of antibiotic resistance in bacteria common to these infections. Staphylococci are the most frequently isolated bacteria in total joint infections, and the prevalence of antibiotic resistance in these organisms among all nosocomial and community-acquired infections has been increasing. As many as 46.7% of Staphylococcus aureus strains and 85.7% of coagulase-negative staphylococci strains are methicillin-resistant. Enterococci also are commonly isolated from infected total joint arthroplasties. The prevalence of vancomycin-resistant enterococci among all enterococci strains is estimated at 23%. As the prevalence of these resistant bacteria continues to increase among all infections, it is anticipated that they will be encountered more regularly in total joint infections. Knowledge of the mechanisms of resistance of these bacteria and currently available and newly developed antimicrobials is key to preventing the expansion of antimicrobial resistance and ensuring the future successful treatment of total joint infections.

Surgical techniques continue to be refined to improve the results of primary cemented total hip arthroplasty. Although there has been much research in the areas of cementation and implant design, little work has specifically addressed how bone preparation can be optimized on the femoral side. On the basis of available scientific data, it appears that the broach-only system has several potential advantages over the traditional ream-and-broach technique. Broaching is usually faster, leaves behind more bone stock, and may improve both microinterlock and macrointerlock. Additionally, the excess bone resulting from broaching without reaming does not seem to compromise fixation at the bone-cement interface. Such differences may become even more important as the indications for cemented hip arthroplasty broaden to include increasingly younger and more active patients, because revision in these individuals is likely. In most cases, reaming is probably counterproductive, although it may be advantageous when used to open the femoral canal, to prevent varus stem orientation, and to manage sclerosis or deformity of bone due to a preexisting hip disorder or the presence of internal fixation devices. Regardless of which method is chosen, good bone surface cleansing and cement penetration remain paramount. More studies comparing reamed and nonreamed preparation are necessary to resolve this controversial issue definitively.

Bone repair models in animals may be considered relevant to human fracture healing to the extent that the sequence of events in the repair process in the model reflect the human fracture healing sequence. In the present study, the relevance of a recently developed segmental defect model in rat fibula to human fracture healing was investigated by evaluating temporal progression of rigidity of the fibula, mineral content of the repair site, and histological changes. In this model, a surgically created 2-mm-long defect was grafted with a 5-mm-long tubular specimen of demineralized bone matrix (DBM) by inserting it over the cut ends of the fibula. The temporal increase in rigidity of the healing fibula demonstrated a pattern similar to biomechanical healing curves measured in human fracture healing. This pattern was characterized by a short phase of rapidly rising rigidity during weeks 4-7 after surgery, associated with a sharp increase in the mineral content of the repair tissue. This was preceded by a phase of nearly zero rigidity and followed by a phase of slow rate of increase approaching a plateau. Histologically, chondroblastic and osteoblastic blastema originating from extraskeletal and subperiosteal (near fibula-graft junction) regions, infiltrated the DBM graft during the first 2 weeks. The DBM graft assumed the role of a "bridging callus." By weeks 6-8, most of the DBM was converted to new woven and trabecular bone with maximal osteoblastic activity and minimal endochondral ossification. Medullary callus formation started with direct new bone formation adjacent to the cortical and endosteal surfaces in the defect and undifferentiated cells in the center of the defect at 3 weeks. The usual bone repair process in rodents was altered by the presence of the DBM graft to recapitulate the sequential stages of human fracture healing, including the formation of a medullary callus, union with woven and lamellar bone, and recreation of the medullary canal.

The last decade has seen the crossover of basic molecular research techniques toward clinical application. The use of molecular diagnostics originally was driven by the desire to identify unculturable or fastidious pathogens. Success in this setting has led to new applications aimed at identifying organisms involved in musculoskeletal infection. Recently, polymerase chain reaction techniques have been investigated as to their efficacy in diagnosing septic arthritis and periprosthetic infection. This paper will offer an introduction to molecular diagnostics, a brief review of several techniques, and update their status in the diagnosis of musculoskeletal infection.

Seventy-four total hip arthroplasties in sixty-six patients were performed, between 1983 and 1986, with use of a Tri-Lock femoral component inserted without cement. This tapered cobalt-chromium component has a fixed head and a circumferential proximal porous coating. Follow-up was conducted with use of a questionnaire, physical examination, and radiographic analysis. At the time of the latest follow-up, fifteen patients (eighteen hips) had died, three patients (four hips) had been lost to follow-up, and one patient (one hip) had refused to participate in the follow-up study; however, the status of fifteen hips at the time of death could be verified. Thus, clinical follow-up data were available for sixty-six of the original seventy-four hips. The average age at the time of the operation was sixty-two years (range, seventeen to eighty-four years), and the average interval between the operation and the latest follow-up evaluation was 10.0 years (range, 8.3 to 11.6 years). The Harris hip score was determined for forty-three hips (forty-one patients) in which the prosthesis was in situ at the time of the latest follow-up. The score was good for thirteen hips and excellent for twenty-eight, so the rate of clinical success was 95 per cent. Two patients had a fair result. One of them had persistent pain and the other had limited motion, but neither had radiographic evidence of loosening of the femoral or acetabular component. All forty-one patients were satisfied with the result. The probability (with standard error) of survival of the femoral component at ten years, with revision as the end point, was 0.95 +/- 0.03. The rate of revision of the femoral component because of aseptic loosening was one (2 per cent) of sixty-six. The overall rate of aseptic loosening of the femoral component in the hips that were followed radiographically was two (4 per cent) of forty-seven. Only one (2 per cent) of the forty-seven acetabular cups had evidence of aseptic loosening. There was no radiographic evidence of distal osteolysis around the prostheses that were well fixed. Proximal osteolysis was present in five (11 per cent) of forty-seven hips, but none of the lesions compromised the stability of the prosthesis or the bone and there were no associated fractures. At an average of ten years postoperatively, the Tri-Lock femoral component functioned well overall and patient satisfaction was high.

In order to evaluate the efficacy of preoperative physical therapy for patients undergoing elective primary total knee arthroplasty, 10 patients completed 6 weeks of physical therapy before surgery (PT group). Ten patients served as controls (C group). Subjects were tested at baseline (PT only), before surgery, 6 weeks after surgery, and 3 months after surgery using the Hospital for Special Surgery knee rating scale, range of motion, thigh circumference, walking speed, Cybex II isokinetic knee flexion, and extension testing, and computed tomography scanning for cross-sectional muscle area. Hospital stay and need for physical therapy after inpatient rehabilitation were also compared. Physical therapy produced modest gains in isokinetic flexion strength in these severely arthritic knees but no difference in extension strength. The decrease in isokinetic strength after surgery was not affected by preoperative physical therapy. Muscle area did not decrease significantly for the PT group, but it did decrease for the C group after surgery. While postoperative strength differences could not be demonstrated, preoperative physical therapy preserved thigh muscle area after surgery. The clinical significance of this finding is uncertain. Consequently, this study failed to support the routine use of preoperative physical therapy in knee replacement surgery.

We retrospectively studied the results of arthrodesis of the knee with a modular titanium intramedullary nail that couples at the knee. The study group consisted of thirteen patients who had a malignant tumor around the knee, five who had failure of a total knee arthroplasty, and three who had a locally destructive benign tumor about the knee. All of the patients were followed for a minimum of two years. Through a single incision at the knee, one nail was inserted retrograde into the femur and the other, antegrade into the tibia; the two nails were joined at the level of the knee by a conical couple and were secured with locking screws. The diameters of the nails were different, to accommodate the dissimilar sizes of the tibial and femoral intramedullary canals. A solid osseous fusion was achieved in nineteen (90 per cent) of the twenty-one patients (sixteen who had had resection of a tumor and three who had had a failed arthroplasty), at an average of 8.4 months (range, three to nineteen months) after the operation. One patient had a delayed union, but fusion was achieved after additional bone-grafting. Of the sixteen patients who were available for clinical and radiographic evaluation at the time of the study, fifteen were satisfied with the over-all outcome and thirteen had either less pain or the same amount of pain as they had had preoperatively. There were no mechanical failures of the implant and no recurrences of tumor. Complications occurred in eight (38 per cent) of the twenty-one patients: three patients had a stress fracture, three had a peroneal nerve palsy (one of which was transient), one had a superficial wound infection, and one had reflex sympathetic dystrophy.

The efficacy of demineralized bone matrix (DBM) used alone and with bone marrow as a graft material in the treatment of osseous defects was evaluated in 48 patients. Of these 48 patients, 39 were available to follow up and review. Follow up averaged 19 months for all patients. In the entire series, 30 of 39 patients demonstrated osseous union for a 77% success rate. Patients with fracture nonunion represented the most recalcitrant group clinically, with union achieved in only 61% of these cases. Overall, the 39 patients grafted with DBM demonstrated healing that was comparable to results achieved with standard iliac crest bone graft. The results indicate the DBM and marrow composite grafting is a suitable alternative to autologous iliac crest bone graft for use in certain clinical situations, such as bone defects in children, comminuted fractures with associated bone loss, nonunited fractures, or to augment an intended arthrodesis site.

Between May 1990 and December 1992, the quadriceps snip was used to assist in the surgical exposure of the knee in 16 patients (4 women and 12 men) who underwent knee surgery at the average age of 65 years (range, 50-73 years). The original diagnoses included osteoarthritis (12 patients), traumatic arthritis (2 patients), rheumatoid arthritis (1 patient), and psoriatic arthritis (1 patient). The surgical exposure was done in the treatment of aseptic loosening of a total knee prosthesis in 8 patients, septic loosening in 2 patients, and primary knee arthroplasty in 6 patients with fibrous ankylosis. Using the Hospital for Special Surgery Scoring System, the authors rated the knees of 10 patients as excellent and those of 6 patients as good at postoperative evaluation. The range of motion was improved in all knees by an average of 30 degrees. Cybex testing revealed significant weakness of the knee in extension when compared with the contralateral normal side at test speeds of 60 degrees and 180 degrees per second but no difference compared with the opposite knee that had been replaced. In the authors' experience, the surgical technique of a quadriceps snip has been safe and simple, has not required special equipment, and postoperatively the patient's physical therapy has not had to be altered. Clinically, the quadriceps strength was very good, although weaker than that of a contralateral normal leg when measured by Cybex testing.

Acetabular fractures are not uncommon injuries of the pelvis. They are most frequently associated with high energy trauma such as that seen in a motor vehicle accident. Management of patients with acetabular fractures includes careful attention to ATLS (advanced Trauma Life Support) protocols and delayed operative treatment of the acetabular fractures. Diagnostic evaluation with plain radiography and CT is used to plan the treatment approach. Treatment includes not only the recognition of the fracture but avoidance of early and late complications. Emergent treatment includes closed reduction of associated hip dislocations followed by skeletal traction. Delayed reconstruction at four days after the injury decreases intraoperative blood loss by allowing retroperitoneal hemorrhage to subside. Final outcome after acetabular trauma depends not only on the reconstruction of the fracture, but the avoidance of complications. Acetabular fractures are becoming an increasingly common orthopedic injury. Fractures of the acetabulum (or hip socket) are most commonly seen after motor vehicle accidents. Young patients (18 to 30 years old) are typically affected. A frequent mechanism of injury is a direct blow to the anterior aspect of the knee with the hip flexed such as a dashboard injury in an automobile accident. Other mechanisms of injury include direct blows to the lateral aspect of the hip as in a fall from a height or a side impact automobile collision.

Patients with chronic renal failure who underwent total hip arthroplasty were retrospectively evaluated. Thirty hips in patients with renal transplants and 16 hips in patients on chronic renal dialysis were reviewed. The average follow-up period was 54 months. The renal transplant patients exhibited generally satisfactory results. Their postoperative course was comparable to that of patients with avascular necrosis undergoing hip reconstruction without underlying renal disease. However, patients undergoing hip arthroplasty while on chronic renal dialysis had poor results (81%), including a deep infection rate of 19%. It was concluded that total hip arthroplasty be reserved for patients who are expecting a renal transplant or preferably those who have already received a successful transplant.

Fat embolization syndrome is a well-known complication associated with total hip arthroplasty. It is believed to be caused by high intramedullary pressures that occur during cement pressurization and femoral stem placement. Fat embolization syndrome has also been reported with intramedullary reaming and placement of an intramedullary alignment guide during total knee arthroplasty. To our knowledge, there have not been previous reports of fatal fat emboli as a result of uncemented hip arthroplasty. The purpose of this case report is to describe a fatality due to fat embolization following a noncemented bipolar arthroplasty.

To determine the diagnosis of patients with infection after total hip replacement may be very difficult, and successful reimplantation is even more challenging. Surgical debridement, removal of all foreign material, and the prosthesis followed by antibiotic therapy are essential for successful eradication of the infection. Reimplantation of the hip allows for functional recovery of the patient. The optimal time for reimplantation of the prosthesis and the role of antibiotic impregnated cement is less clear. A review of the literature strongly favors a two-stage reimplantation with local antibiotic delivery with successful results of approximately 93%.

Early failure caused by wear of the polyethylene bearing surface of a metal-backed tibial platform or a metal-backed patellar component in a total knee prosthesis has been a recognized complication; patients with these problems initially have pain and instability. A patient who had a cystic mass in the distal thigh was evaluated, and osteolysis of the distal femur was detected. Polyethylene debris and reactive synovium were confirmed surgically and histologically, indicating a cause-effect relationship of polyethylene wear debris and failure of the total knee arthroplasty. Regular and long-term patient follow-up evaluation after total joint arthroplasty is essential for the detection of early evidence of occult polyethylene wear.

The purpose of this study was to examine the mating surfaces of femoral heads and stems for evidence of corrosion, and to evaluate the quality of the taper lock of modular hip prostheses. Forty-eight implants with three different designs were evaluated. Group I (26 implants) had a cobalt alloy head and cobalt alloy stem. Group II (ten implants) had a cobalt alloy head and a titanium stem. Group III (12 implants) had a cobalt alloy head with a titanium stem that was coupled in the factory via a shrink fit. The implants were examined under light microscopy and scanning electron microscopy. In cases where the femoral head was still assembled to the stem, pull-off testing was performed using an MTS machine. The average failure load for the pull-off tests for each group of prostheses was as follows: Group I (nine implants) 3,003 N +/- 623 N; Group II (six implants) 4453 N +/- 570 N; and Group III (12 implants) 6859 N +/- 3525 N. The Group III implants required a significantly greater pull-off force than those in Group I (p = 0.002). There was no evidence of corrosion in Group I. In Group II, crevice corrosion was noted in one taper interface and there was fretting in two other tapers. No corrosion was noted in Group III. Improving the tolerances of the mating surfaces may be a key factor in preventing corrosion. This would not only increase the forces that are necessary to debond the matting surfaces, but also decrease corrosion by reducing micromotion and fluid at the taper interface.

Total joint replacement has become one of the more common orthopaedic operations, with approximately 240,000 major joint arthroplasties performed annually in the United States, a large percentage of these being of the hip. The vast majority of hip replacements are for the diagnosis of degenerative arthritis and are performed in patients greater than 60 years of age. Less commonly the procedure is performed for other diagnoses (eg, developmental disorders of the hip, inflammatory arthritis, and post-traumatic arthritis) and in younger patients. Each of these diagnoses are associated with unique characteristics posing an array of technical challenges for the surgeon. The purpose of this manuscript is to highlight the more common of these processes with emphasis on the technical difficulties encountered when reconstructing these hips.

Between 1983 and 1986, 40 hip arthroplasties in 40 patients with documented deep infection were reimplanted using Palacos Gentamicin at The Hospital for Special Surgery. Palacos Gentamicin was added to the standard protocol, which included removal of the prosthesis, cement, if present, and a thorough debridement of infected and necrotic tissue, six weeks of intravenous antibiotics with a postpeak serum bactericidal titer of at least 1:8 against the infecting bacteria, followed by reimplantation of the hip. Sixteen of the patients also had the placement of gentamicin-impregnated beads at the time of prosthetic removal. All patients had a deep periprosthetic infection, 13 with Staphylococcus epidermidis, seven Staphylococcus aureus, four Streptococcus, three Enterococcus, three with gram-positive bacteria, four Escherichia coli, two Proteus, one Pseudomonas, and three anaerobic organisms. At an average follow-up period of five years (range, two to ten), two of the 40 hips (5%) developed recurrent infection. These cases recurred at one month in a patient immunocompromised by end-stage systemic lupus erythematosus (S. epidermidis) and at five months in a patient with severe titanium metallosis (S. aureus). No recurrence was noted in eight cases with gram-negative organisms or in three cases of mixed infections. No infection recurred after five months in the remaining patients before their death or last follow-up examination. Of the remaining 38 hips, 16 died of causes unrelated to the hip, leaving 21 with an average follow-up period of 7.5 years. Clinical results in these patients were 14 excellent, five good, two fair, and no poor results.(ABSTRACT TRUNCATED AT 250 WORDS)