Infected total knee arthroplasties

Thirty infected total knee arthroplasties were investigated in 29 patients over an average interval of 42 months. Eleven infections began in the immediate perioperative period. Six developed from postoperative wound-healing problems. The remainder were late infections. Staphylococcus was found in 16 infections, gram-negative agents in five, mixed organisms in five, and other gram-positives in four. Sixteen knees were arthrodesed, six knees were treated by retention of the components, and two above-knee amputations and one resection arthroplasty were performed. Five patients had two-stage revisions to new components. Evidence of persistent infection was present in three arthrodeses, two retained arthroplasties, and one knee that was revised. Perioperative infections were associated with staphylococcal organisms and responded less favorably to conservative treatment. The failure of primary wound healing demands immediate measures to obtain skin coverage. Retention of the arthroplasty components is possible only in selected patients.     

Cemented total knee arthroplasties

INTRODUCTION: The aseptic loosening of cemented total knee arthroplasties is still an unsolved problem. In this regard, the hydrolysis resistance in the metal-to-bone cement interface is of major importance. MATERIAL AND METHODS: Cemented pre-treated tibia components coated by means of a silica/silane interlayer system of the model "Columbus PS" were dynamically loaded with the help of a knee-simulator similar to DIN ISO 14243. After loading, the components were microscopically analysed concerning debonding in the metal-to-bone cement interface as well as with regard to cement mantle defects. These data were matched with uncoated "Columbus PS" components. Unloaded coated and uncoated tibia components acted as a control. RESULTS: In comparison with uncoated tibia components, the pre-treated and coated ones yielded a highly significant reduction of cement defects (p < 0.01) as well as a significant reduction of debonding in the metal-to-bone cement interface (p < 0.05). CONCLUSION: By means of the silica/silane interlayer system for cemented tibia components, a hydrolytic debonding in the metal-to-bone cement interface with subsequent mechanical loosening and consecutive early cement mantle failure can be significantly reduced. This could lead to an increased long-term stability of the metal-to-bone cement compound with decreased aseptic loosening in clinical use.     

Management of infected total knee arthroplasty

A retrospective study of the Mayo Clinic experience with the management of 61 infected total knee arthroplasties treated between 1970 and 1980 revealed rheumatoid arthritis as an underlying diagnosis in 47%. Previous operations had been performed in 58%. Arthrodesis was the most frequently utilized salvage technique and was successful in 83%. Reimplantation of a new prosthesis was successful in 63%. Debridement alone was successful in six knees when performed early for acute infections.     

Revision of infected knee arthroplasties in Denmark

Background and purpose — The surgical treatment of periprosthetic knee infection is generally either a partial revision procedure (open debridement and exchange of the tibial insert) or a 2-stage exchange arthroplasty procedure. We describe the failure rates of these procedures on a nationwide basis.

Patients and methods — 105 partial revisions (100 patients) and 215 potential 2-stage revision procedures (205 patients) performed due to infection from July 1, 2011 to June 30, 2013 were identified from the Danish Knee Arthroplasty Register (DKR). Failure was defined as surgically related death ≤ 90 days postoperatively, re-revision due to infection, or not reaching the second stage for a planned 2-stage procedure within a median follow-up period of 3.2 (2.2–4.2) years.

Results — The failure rate of the partial revisions was 43%. 71 of the partial revisions (67%) were revisions of a primary prosthesis with a re-revision rate due to infection of 34%, as compared to 55% in revisions of a revision prosthesis (p = 0.05). The failure rate of the 2-stage revisions was 30%. Median time interval between stages was 84 (9–597) days. 117 (54%) of the 2-stage revisions were revisions of a primary prosthesis with a re-revision rate due to infection of 21%, as compared to 29% in revisions of a previously revised prosthesis (p = 0.1). Overall postoperative mortality was 0.6% in high-volume centers (> 30 procedures within 2 years) as opposed to 7% in the remaining centers (p = 0.003).

Interpretation — The failure rates of 43% after the partial revision procedures and 30% after the 2-stage revisions in combination with the higher mortality outside high-volume centers call for centralization and reconsideration of surgical strategies.     

The use of an articulating spacer in the management of infected total knee arthroplasties

Eleven infected total knee arthroplasties underwent revision using an articulating spacer comprising a total condylar component and meniscal polyethylene insert cemented in place using antibiotic-loaded cement. Only 1 case required subsequent rerevision for infection, 2 were revised for pain, 6 remain in situ, and 2 patients have died with their spacers in situ. Average Knee Society clinical rating for the spacers left implanted is 167 at an average of 65 months. This articulating spacer appears not to require mandatory second-stage surgery, although should this prove necessary, then it is relatively straightforward to perform.     

Reinfusion of whole blood after revision surgery for infected total hip and knee arthroplasties

Because of its proven effectiveness in reducing the need for banked blood transfusions following total joint arthroplasty, the indications for postoperative blood retrieval were expanded to include seven cases of infected total knee or hip arthroplasties where a one-stage exchange procedure was performed. Each joint had been aspirated after surgery and had positive cultures but no gross pus at the time of revision surgery. Each of the operations included debridement with reimplantation of a cementless prosthesis under cover of intravenous antibiotics for 48 hours followed by oral treatment until discharge. Antibiotic-soaked morselized bone graft was used in all patients to restore deficient nonstructural bone. Wound drainage blood was retrieved and reinfused during the first 8 hours after surgery, averaging 958 cc. Banked blood usage averaged 2.4 U (88% homologous) with an average blood loss of 1,974 cc. One patient experienced shaking chills during a second reinfusion of 600 cc of blood without stoppage of the transfusion. Wound hematoma occurred in one patient but did not require surgical evacuation. No patient developed evidence of septicemia.     

Infection prevention in total knee and total hip arthroplasties

Infection after primary joint arthroplasty is responsible for severe morbidity to the patients and staggering costs to society. Understanding the patient population undergoing these procedures and the use of appropriate prophylactic regiments and precautions in the perioperative and postoperative periods is crucial for the ultimate success of the procedures. In this article, we review the current related literature and our techniques for reducing the likelihood of infection after total knee and total hip arthroplasties.     

Surgical waste audit of 5 total knee arthroplasties

Background

Operating rooms (ORs) are estimated to generate up to one-third of hospital waste. At the London Health Sciences Centre, prosthetics and implants represent 17% of the institution’s ecological footprint. To investigate waste production associated with total knee arthroplasties (TKAs), we performed a surgical waste audit to gauge the environmental impact of this procedure and generate strategies to improve waste management.

Methods

We conducted a waste audit of 5 primary TKAs performed by a single surgeon in February 2010. Waste was categorized into 6 streams: regular solid waste, recyclable plastics, biohazard waste, laundered linens, sharps and blue sterile wrap. Volume and weight of each stream was quantified. We used Canadian Joint Replacement Registry data (2008–2009) to estimate annual weight and volume totals of waste from all TKAs performed in Canada.

Results

The average surgical waste (excluding laundered linens) per TKA was 13.3 kg, of which 8.6 kg (64.5%) was normal solid waste, 2.5 kg (19.2%) was biohazard waste, 1.6 kg (12.1%) was blue sterile wrap, 0.3 kg (2.2%) was recyclables and 0.3 kg (2.2%) was sharps. Plastic wrappers, disposable surgical linens and personal protective equipment contributed considerably to total waste. We estimated that landfill waste from all 47 429 TKAs performed in Canada in 2008–2009 was 407 889 kg by weight and 15 272 m³ by volume.

Conclusion

Total knee arthroplasties produce substantial amounts of surgical waste. Environmentally friendly surgical products and waste management strategies may allow ORs to reduce the negative impacts of waste production without compromising patient care.

Level of evidence

Level IV, case series.     

Outcome of total knee arthroplasties after renal transplantation

The fate of total knee arthroplasty in renal graft recipients is unknown. We retrospectively reviewed the outcome of 16 total knee arthroplasties (TKAs) performed after renal transplantation in 12 renal graft recipients from February 1997 to December 2003. The patients (mean age 63) were submitted to a clinical evaluation using the Knee Society Score (KSS) and a radiological evaluation using the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation. The follow-up period averaged 65 (range 25–107) months. No knee had to be revised and one patient died during the follow-up period. The mean knee score was 97.1 (range 93–100) and the mean function score was 87.7 (range 60–100). The alignments of the prosthetic components were correct for all but one patient who, however, kept a good knee score (95). No case of aseptic loosening or osteolysis was detected at last X-rays examination. We conclude that TKA is a safe and symptomatically effective treatment of knee osteonecrosis or severe osteoarthritis in renal graft recipients and should thus be proposed in this population when symptomatology becomes significant. Long-term follow-up studies are necessary to confirm this initial report.     

Infection prevention in total knee and total hip arthroplasties.

Infection after primary joint arthroplasty is responsible for severe morbidity to the patients and staggering costs to society. Understanding the patient population undergoing these procedures and the use of appropriate prophylactic regiments and precautions in the perioperative and postoperative periods is crucial for the ultimate success of the procedures. In this article, we review the current related literature and our techniques for reducing the likelihood of infection after total knee and total hip arthroplasties.     

Periprosthetic fractures in patients with total knee arthroplasties

Ten patients with total knee arthroplasties sustained periprosthetic fractures. Nine of these were supracondylar fractures, and one occurred in the middle one-third of the tibia. These patients were treated with conservative methods in two cases and internal fixation with plate and screws in three cases. The remaining five patients were treated with intramedullary fixation using a specially designed revision prosthesis with long intramedullary stems. The best results wer achieved through the revision arthroplasty, based on walking ability, range of motion, and early rehabilitation.     

Economics of one-stage versus two-stage bilateral total knee arthroplasties

Patients requiring bilateral total knee arthroplasties may have both joints replaced simultaneously during one hospitalization (one-stage) or during two separate hospitalizations (two-stage). The goals of the current study were to retrospectively analyze discharge patterns for 91 patients who had one-stage bilateral total knee arthroplasties and 32 patients who had two-stage surgeries, and to quantify their in-hospital costs and their costs if the patients were discharged from the hospital to an inpatient unit. Patients having one-stage and two-stage surgery were similar in age, gender, severity of illness (as measured by the American Society of Anesthesiologists Physical Status score), principal diagnosis, and ethnicity. Using a microcosting approach, the authors found that the average in-hospital costs for one-stage total knee arthroplasty (27,468 US dollars) were significantly lower (by 24%) than for two-stage total knee arthroplasty. However, 38% of patients who had the one-stage bilateral total knee arthroplasties were admitted to an acute rehabilitation unit, which had a mean cost of 6469 US dollars and length of stay of 9 days. In contrast, none of the patients who had the two-stage procedure required acute rehabilitation. Patients who had the two-stage procedure were discharged directly home (or with home health services) 42% of the time, versus 21% for patients who had the one-stage procedure. Patients from both groups were discharged to a skilled nursing facility approximately (1/2) of the time, accruing similar costs. Economic analyses of the one-stage procedure need to consider that these patients will require increased use of acute inpatient rehabilitation after hospital discharge.     

Comparison of fixed-bearing and mobile-bearing total knee arthroplasties.

The purpose of the current study was to directly compare the results of fixed-bearing and mobile-bearing total knee arthroplasties in the same patient who had bilateral simultaneous total knee replacements. A fixed-bearing total knee prosthesis (AMK) was implanted in one knee and a mobile-bearing total knee prosthesis (LCS) was implanted in the other knee in 116 patients. The average age of the patients was 65 years (range, 33-70 years). The average followup was 7.4 years (range, 6-8 years). Clinical and radiographic followup was done using Knee Society and Hospital for Special Surgery knee rating systems at 6 weeks, 3 months, 6 months, 1 year after surgery, and yearly thereafter. Total knee score, pain score, mean functional score, and range of motion were comparable in both groups. Two knee replacements (2%) in one patient with AMK prostheses were revised because of complete wear of tibial bearing polyethylene. One knee replacement (1%) in one patient with an LCS prosthesis was revised because of dislocation of the medial tibial bearing polyethylene and one knee replacement (1%) in one patient with an LCS prosthesis was revised because of complete wear of the medial tibial bearing polyethylene. No knee had aseptic loosening or osteolysis in either group. After a minimum followup of 6 years, the results of fixed- and mobile-bearing total knee prostheses in the current series are favorable. However, there is no evidence to prove the superiority of the mobile-bearing total knee design.     

Supracondylar nailing of periprosthetic fractures above total knee arthroplasties

Supracondylar nailing was performed in 10 patients who sustained periprosthetic fractures above total knee arthroplasties. The fractures occurred in women with an average age of 67.4 years (range, 42–92 years). All fractures healed in a satisfactory alignment in an average duration of 13.2 weeks (range, 12–18 weeks). None of the fractures needed bone grafting. There were no cases of wound infections, nonunion or delayed union. All patients achieved satisfactory range of movement of the knee joint and preoperative functional status. Main complications included loosening of a distal screw in one patient and fracture above the short nail following a second injury in another patient. Use of a longer nail where possible and a condylar bolt for distal locking can easily avoid these complications. We conclude that supracondylar nailing, despite some limitations, is a satisfactory method of treatment for a majority of displaced periprosthetic fractures above well-fixed total knee arthroplasties.     

Radionuclide imaging of asymptomatic versus symptomatic total knee arthroplasties

Ninety-eight total knee prostheses were evaluated by roentgenograms and bone scans. Fifty-three were asymptomatic, and 45 were symptomatic. Thirteen prostheses required revision surgery. At a mean of 54 months, asymptomatic knee replacements generally showed only mild uptake in one or more zones. Only one knee had uptake equal to surrounding bone. However, symptomatic knee replacements showed significantly greater uptake in the patella, femur, and medial and lateral tibial plateau regions (Mann-Whitney two-sample rank test). Bone scans in the symptomatic group were obtained at a mean of 44 months. Excluding those patients who had revision surgery, the differences remained significant. Furthermore, symptomatic knee replacements with normal roentgenograms also had significantly greater uptake. Radiolucent lines were noted in 30% of asymptomatic patients, whereas 29% of symptomatic knees had radiolucencies. Radiolucencies were not generally associated with significantly greater uptake. Lateral release had no effect on the patellar score.     

The value of indium 111 leukocyte scanning in the evaluation of painful or infected total knee arthroplasties

Evaluation of painful total knee arthroplasties (TKAs) for infection can be difficult. Indium 111 (111In) leukocyte bone scanning provides a minimally invasive technique for evaluation of possible infection. Thirty-eight patients with a painful TKA who had surgical exploration after 111In leukocyte scanning were reviewed. The scan had an accuracy of 84%, a sensitivity of 83%, and a specificity of 85%. The 111In leukocyte scans must be interpreted in conjunction with the clinical evaluation of the patient because they are less accurate for study of TKAs than of total hip arthroplasties.