Josep Riba

Usefulness of histological analysis for predicting the presence of microorganisms at the time of reimplantation after hip resection arthroplasty for the treatment of infection.

BACKGROUND Appropriate interpretation of a frozen section has a relatively high specificity and sensitivity for the diagnosis of infection when septic loosening of a prosthesis is suspected. However, its usefulness for predicting the presence of microorganisms at the time of reimplantation after hip resection arthroplasty for the treatment of infection is not well defined. The aim of the present study was to evaluate the usefulness of histological analysis in this situation. METHODS From January 2002 to February 2006, a total of twenty-one patients underwent reimplantation after hip resection arthroplasty for the treatment of infection. Histological studies and cultures of specimens of periprosthetic tissue that had been obtained at the time of reimplantation were retrospectively reviewed. The results of culture were considered positive when the same microorganism was isolated in at least two samples. Two histological criteria were used to diagnose infection: (1) Criterion A (the Feldman criterion), defined as the presence of at least five neutrophils per high-power field (x400) in at least five separate microscopic fields and (2) Criterion B (the Athanasou criterion), defined as the presence of at least one neutrophil per high-power field (x400), on average, after examination of ten microscopic fields. The sensitivity, specificity, positive predictive value, and negative predictive value of each of these criteria were calculated with use of microbiological results as the gold standard for defining infection. RESULTS Seven of the twenty-one patients had a positive result on culture, and the most common microorganism was coagulase-negative staphylococcus. The sensitivity, specificity, positive predictive value, and negative predictive value of frozen-section analysis were 28.5%, 100%, 100%, and 73.6%, respectively, according to the Feldman criterion and 71.4%, 64.2%, 50%, and 81.8%, respectively, according to the Athanasou criterion. The numbers of lymphocytes and plasma cells did not help in the diagnosis of infection. Fibrosis was more common in patients without an infection. CONCLUSIONS The probability of infection is high when at least five neutrophils per high-power field are found in the periprosthetic tissue, but it is not possible to rule out infection when the number of neutrophils is less than five. LEVEL OF EVIDENCE Diagnostic Level I.

Timing of Antibiotic Prophylaxis for Primary Total Knee Arthroplasty Performed during Ischemia

BACKGROUND There is no clinical trial analyzing the best moment to infuse an antibiotic during knee arthroplasty performed during ischemia. We designed a single-center, randomized, double-blind, placebo-controlled trial to evaluate whether antibiotic therapy should be administered before tourniquet inflation or just before tourniquet deflation. MATERIAL AND METHODS Patients who underwent a primary knee arthroplasty were randomized to receive (1) 1.5 g of cefuroxime 10-30 min before inflation of the tourniquet and placebo 10 min before release of the tourniquet (standard arm) or (2) placebo 10-30 min before inflation of the tourniquet and 1.5 g of cefuroxime 10 min before release of the tourniquet (experimental arm). In both arms, a postoperative dose of 1.5 g of cefuroxime was given 6 h after the surgical procedure. The main variables associated with the rate of deep-tissue infection after 3 and 12 months of follow-up were gathered. Continuous variables were compared using Students t test, and categorical variables were compared using the chi(2) test or Fishers exact test. RESULTS From September 2004 through December 2005, a total of 908 patients were randomized, 442 and 466 of whom were allocated to the standard and experimental arms, respectively. There were no differences between treatment arms in terms of age, sex, comorbidity, American Society of Anaesthesiologists score, duration of surgery, need of blood transfusion, or fourth-day hematocrit. The rates of deep-tissue infection among the standard and experimental groups were 3.4% and 1.9%, respectively, at 3 months of follow-up (P = .21) and 3.6% and 2.6%, respectively, at 12 months of follow-up (P = .44). CONCLUSION The administration of prophylactic antibiotics just before tourniquet release was not inferior to standard antibiotic prophylaxis.

Pathological fractures in patients who have amyloidosis associated with dialysis. A report of five cases.

We are reporting the cases of five patients in whom a pathological fracture of the femoral neck developed secondary to massive deposition of amyloid while they were receiving maintenance hemodialysis. The immunohistochemical studies demonstrated the presence of beta-2-microglobulin as the major constituent protein of the amyloid deposits.

Low sensitivity of histology to predict the presence of microorganisms in suspected aseptic loosening of a joint prosthesis.

Intraoperative histology has a high specificity and sensitivity when a septic prosthesis loosening is suspected. However, its usefulness to predict the presence of microorganisms when aseptic loosening is suspected is not well defined. Intraoperative histology and cultures from periprosthetic tissue of 61 revision arthroplasties performed owing to suspected aseptic loosening were retrospectively reviewed. Frozen sections were evaluated following Mirras criteria (adapted by Feldman). Culture was considered positive when the same microorganism was isolated in at least two samples. The cultures were positive in 12 cases and coagulase-negative staphylococci were the most common microorganisms (11 cases). In six out of 12 cases (50%), the histology revealed more than five polymorphonuclear leukocytes per high-power field. The sensitivity, specificity, positive and negative predictive value of histology to detect the presence of microorganisms was 50, 81, 40 and 86%, respectively. In conclusion, intraoperative histology using Mirras criteria had a low sensitivity to predict the presence of microorganisms in samples from suspected aseptic prosthetic loosening.

Interface membrane is the best sample for histological study to diagnose prosthetic joint infection

The objective of our study was to study which is the most accurate specimen for histological diagnosis of prosthetic joint infections (pseudocapsule or interface membrane). This is a prospective study including hip revision arthroplasties performed from January 2007 to June 2009. Specimens from pseudocapsule and from interface membrane were obtained from each patient. The histology was considered positive for infection when ≥5 neutrophils per high-power field ( × 40) were found. Definitive diagnosis of infection was considered when ≥2 cultures were positive for the same microorganism. According to the definition of infection, patients were classified in two groups: (A) patients with aseptic loosening in whom cultures obtained during surgery were negative and (B) patients with prosthetic joint infection. A total of 69 revisions were included in the study; 57 were classified in group A and 12 in group B. In group B, the percentage of positive interface membrane histology was significantly higher than the percentage of positive pseudocapsule histology (83 vs 42%, P=0.04, Fishers exact test). The results suggest that periprosthetic interface membrane is the best specimen for the histological diagnosis of prosthetic joint infection.

Total hip arthroplasty in hemodialysis and renal transplant patients

Osteoarticular complications are common in patients with chronic renal failure and they often require implantation of a hip arthroplasty (total or partial) due to osteoarthritis, femoral neck fracture or ischemic necrosis of multifactor aetiology. Between 1992 and 2005 we operated on eighteen patients (23 hips) with chronic renal failure who were receiving renal replacement therapy (ten haemodialysis and eight renal transplants), and in each case either a total or partial hip arthroplasty was implanted. This group comprised nine women and nine men, with a mean age of 56 years (range: 30-83). Five cases were bilateral. The clinical diagnoses were necrosis (fourteen cases), femoral neck fracture (five cases) and osteoarthritis (three cases). The main early complications were haemorrhage in seventeen cases (74%) and infection in six cases (33%) (two urinary infections and four of the surgical wound). The late complications involved eight cases (35%) of prosthetic loosening (five aseptic and three septic). The surgery-related mortality rate was 17% (three cases). Prosthetic hip surgery in patients receiving renal replacement therapy is associated with high morbidity and mortality, thus highlighting the importance of careful patient selection.

Alignment guided by computer navigation of the femoral component in hip resurfacing

Surgical navigation systems are offered to provide more precise implantation of the femoral component in hip resurfacing (HR), allowing to reduce the risk of malpositioning and of femoral neck fracture and notching. We conducted a retrospective analysis of 30 HR divided into two cohorts and compared the results of a nonnavigated group (15 hips) with those of a navigated group (15 hips). The BrainLAB Computer Navigation System was used in all cases. No notching occurred in either group. The femoral component did not show better positioning in the navigated group, but more outlier cases were observed in the nonnavigated group (7, versus 3 in the navigated group). Although there are no long-term studies showing that surgical navigation increases the survival of HR, the avoidance of outlier values justifies its use, especially during the surgical learning curve, which is a difficult and lengthy one.

Plate Osteosynthesis for Severe Olecranon Fractures

Purpose. To review outcomes of 10 patients who underwent plate osteosynthesis for severe olecranon fractures. Methods. Records of 7 men and 3 women aged 33 to 73 years who underwent plate osteosynthesis for severe olecranon fractures were reviewed. All had some degree of soft-tissue injury; 6 presented with associated fractures. Seven patients were treated with a limited contact dynamic compression plate, and the remaining 3 received a locking compression plate. Patients were followed up for fracture healing, range of motion, nerve damage, heterotopic ossification, infection, hardware complaints, and the need of a secondary surgical procedure. The Mayo Elbow Performance Score (MEPS) was determined at the final follow-up. The patient-answered questionnaire (PAQ) portion of the Liverpool Elbow Score (LES) was evaluated 2 to 37 months later by telephone. Results. All patients had bone union. None had nerve damage or heterotopic ossification. Patients 4, 6, and 8 with type-IIIB fractures developed deep infections and severe soft-tissue swelling; all had been treated with the limited contact dynamic compression plate. Four patients underwent plate removal owing to hardware complaints. One patient underwent a secondary procedure to restore complete range of elbow motion. The mean MEPS score was 84 (range, 35–100); 5 patients attained excellent scores, one good, 2 satisfactory, and 2 unsatisfactory. The mean PAQ portion of the LES score was 31 (range, 23–36). Conclusion. Plate osteosynthesis achieves satisfactory results for severe olecranon fractures. The deep infection rate is higher in patients with severe soft-tissue injury.

Assessment of Patients with a DePuy ASR Metal-on-Metal Hip Replacement: Results of Applying the Guidelines of the Spanish Society of Hip Surgery in a Tertiary Referral Hospital.

The prognosis associated with the DePuy ASR hip cup is poor and varies according to the series. This implant was withdrawn from use in 2010 and all patients needed to be assessed. We present the results of the assessment of our patients treated with this device, according to the Spanish Society of Hip Surgery (SECCA) algorithm published in 2011. This retrospective study evaluates 83 consecutive ASR cups, followed up at a mean of 2.9 years. Serum levels of chromium and cobalt, as well as the acetabular abduction angle, were determined in order to assess their possible correlation with failure, defined as the need for revision surgery. The mean Harris Hip Score was 83.2 (range 42–97). Eight arthroplasties (13.3%) required revision due to persistent pain and/or elevated serum levels of chromium/cobalt. All the cups had a correct abduction angle, and there was no correlation between elevated serum levels of metal ions and implant failure. Since two previous ASR implants were exchanged previously to the recall, the revision rate for ASR cups in our centre is 18.2% at 2.9 years.

Field trapping of the flathead oak borer Coroebus undatus (Coleoptera: Buprestidae) with different traps and volatile lures

The flathead oak borer Coroebus undatus F. (Coleoptera: Buprestidae) is one of the primary pests of cork oak Quercus suber L. in the Mediterranean region causing great economic losses to the cork industry. Very little is known about its biology and behavior and, so far, no control measures have been established. We present the results of a pilot study aimed to develop an efficient trapping method for monitoring this harmful pest. In a 3‐year field study, purple‐colored prism traps baited with a mixture of green leaf volatiles (GLVs) from the host have been shown the most effective combination to catch C. undatus adults (solely females) compared to other trap and lure types tested. Wavelength and reflectance measurements revealed that purple traps exhibit reflectance peak values similar to those found in the abdominal and elytral cuticle of both sexes, suggesting the involvement of visual cues for mate location in this species. The data presented are the first to demonstrate captures of adults of the genus Coroebus by an attractant‐based trapping method.