Xavier Gallart

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.

Neutrophils in frozen section and type of microorganism isolated at the time of resection arthroplasty for the treatment of infection

IntroductionThe histology of periprosthetic tissue is a gold standard for the diagnosis of periprosthetic joint infection. However, the specificity and sensitivity of histology has never been 100%. In the present study we hypothesized that the type of microorganism could be related to the effectiveness of histology in the detection of infection.Material and methodsFrozen sections and cultures from periprosthetic tissue of 38 revision arthroplasties taken at the time of resection arthroplasty for the treatment of infection were retrospectively reviewed. Frozen sections were evaluated following Feldman’s criteria. A culture was considered positive when the same microorganism was isolated in at least two samples or when pus was present around the prosthesis. The literature providing information on histology and microbiology of arthroplasty-associated infection was reviewed.ResultsCoagulase-negative staphylococcus (CNS) was the etiology in 13 cases, Gram-negative bacilli in 8, Staphylococcus aureus in 7, Candida sp in 2, Peptococcus sp in 2, Enterococcussp in 1 and S. pneumoniae in 1. No microorganism was isolated in four cases. Almost all the frozen sections in the 38 cases were positive except in 2 of the 13 that were caused by CNS (15.3%). The articles reviewed supported our findings.ConclusionFrozen section is a useful test to intraoperatively confirm an infection when preoperative septic loosening is suspected. However, histology has false-negative results when the infection is due to low-virulence microorganisms.

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.

Tratamiento de la infección aguda de la artroplastia total o parcial de cadera con desbridamiento y régimen antibiótico oral

Fundamento y objetivo: El antibiotico o la asociacion de antibioticos y la duracion optima del tratamiento de la infeccion aguda de una protesis de cadera (IAPC) no estan bien definidos. Pacientes y metodo: Se estudio a 32 pacientes con IAPC diagnosticada en los dos meses siguientes a la intervencion. En todos los casos se realizo desbridamiento quirurgico, se tomaron muestras para cultivo y se inicio tratamiento antibiotico ajustado a los resultados del antibiograma. Se efectuaron controles ambulatorios al menos hasta 18 meses despues de finalizado el tratamiento. Resultados: La infeccion fue de etiologia estafilococica en 16 casos, estreptococica en dos, enterococica en 6 y por un bacilo gramnegativo (BGN) en 6. En dos pacientes no se identifico el microorganismo causal. Los pacientes con infeccion por cocos grampositivos (no enterococos) recibieron tratamiento durante una media de 2,7 meses con una combinacion de antibioticos que incluia rifampicina. La evolucion fue favorable en el 100% de los casos evaluables, tras un seguimiento medio de 20,7 meses. Los pacientes con infeccion por enterococo fueron tratados con un glucopeptido o un betalactamico durante una media de 2,6 meses y todos evolucionaron desfavorablemente. De las 6 infecciones causadas por BGN, dos fueron evaluables y evolucionaron de forma favorable. Conclusiones: La IAPC producida por Staphylococcus sp. o Streptococcus sp. puede tratarse con gran probabilidad de exito con desbridamiento quirurgico y una pauta de tratamiento antibiotico que contenga rifampicina durante un periodo no superior a tres meses. Es necesario analizar la eficacia de nuevos antibioticos o combinaciones de antibioticos en caso de infeccion enterococica.

Utilidad de la adición de antibiótico al cemento en el recambio en 1 tiempo en la infección crónica de una prótesis total de cadera

BACKGROUNDS AND OBJECTIVE: Direct exchange using antibiotic-impregnated cement is a treatment option for hip prosthesis infection (HPI). Nevertheless, a local antibiotic use is not always possible. We present our experience with direct exchange with and without antibiotic-impregnated cement. PATIENTS AND METHOD: Fourteen patients with a HPI were treated with direct exchange. The femoral component was cemented with an antibiotic in 7 cases and in 7 it was not cemented. The patients received antibiotic prophylaxis and antibiotic treatment for a mean of 3 months. Clinical evolution of the infection was prospectively assessed. RESULTS: There were no differences with regard to the clinical and microbiologic characteristics between both groups. In the last control (minimum 2 years) all the patients were cured. CONCLUSIONS: Our results suggest that direct exchange without local antibiotic is an option in HPI. Further studies are needed to evaluate the usefulness of antibiotic loaded cement.

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.

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.

Luxación recidivante de prótesis total de cadera

Mas del 50% de los casos de caderas inestables se pueden resolver mediante la reduccion cerrada de la luxacion. Un intento sistematico para entender la causa de la inestabilidad, normalmente suele conducir a un tratamiento eficaz del problema cuando hace falta cirugia. Los componentes constrenidos o de retencion han mejorado las posibilidades de resolver los problemas dificiles de inestabilidad, pero los efectos negativos potenciales de estos componentes deben tenerse tambien en cuenta. Los implantes tripolares, cuyos resultados clinicos en la literatura son muy alentadores, ocupan un lugar de eleccion en el arsenal terapeutico de la inestabilidad protetica.

Dislocation of Preformed Antibiotic-Loaded Cement Spacers (Spacer-G): Etiological Factors and Clinical Prognosis

This study assesses the factors associated with the dislocation of the Spacer-G and its clinical prognosis. Seventy-four spacers were reviewed. Acetabular bone defects, proximal femoral cementation of the spacer and its relationship to the size of the head spacer were not associated with dislocation. The only variable that it was possible to associate with dislocation was when the previous stem, prior to the spacer placement, was a cemented stem. In patients who experienced a dislocation, infection was not cured during the interim period more frequently than patients who had not experienced a dislocation (P = 0.001) and the final clinical hip evaluation was also worse (P < 0.001). The study concludes that the surgeon should assess different surgical aspects in order to avoid mechanical complications such as dislocation and its consequences.