Jean-Pierre Courpied

A comparison of patient-specific and conventional instrumentation for total knee arthroplasty

In this study we randomised 140 patients who were due to undergo primary total knee arthroplasty (TKA) to have the procedure performed using either patient-specific cutting guides (PSCG) or conventional instrumentation (CI). The primary outcome measure was the mechanical axis, as measured at three months on a standing long-leg radiograph by the hip-knee-ankle (HKA) angle. This was undertaken by an independent observer who was blinded to the instrumentation. Secondary outcome measures were component positioning, operating time, Knee Society and Oxford knee scores, blood loss and length of hospital stay. A total of 126 patients (67 in the CI group and 59 in the PSCG group) had complete clinical and radiological data. There were 88 females and 52 males with a mean age of 69.3 years (47 to 84) and a mean BMI of 28.6 kg/m(2) (20.2 to 40.8). The mean HKA angle was 178.9° (172.5 to 183.4) in the CI group and 178.2° (172.4 to 183.4) in the PSCG group (p = 0.34). Outliers were identified in 22 of 67 knees (32.8%) in the CI group and 19 of 59 knees (32.2%) in the PSCG group (p = 0.99). There was no significant difference in the clinical results (p = 0.95 and 0.59, respectively). Operating time, blood loss and length of hospital stay were not significantly reduced (p = 0.09, 0.58 and 0.50, respectively) when using PSCG. The use of PSCG in primary TKA did not reduce the proportion of outliers as measured by post-operative coronal alignment.

Total joint replacement and blood loss: what is the best equation?

With the population aging, total joint replacements which are an effective method to restore patient’s mobility are an increasing necessity. However, such operations are known to entail serious blood loss, which may have dramatic consequences in patients with chronic diseases or when the prosthesis is revised, a situation where the blood loss is even higher. Therefore, formulas to better estimate the blood loss are available. These formulas may also be used for clinical studies to compare blood loss between different joint replacement techniques. The aim of this review is to provide a clear understanding of the formulas and to help physicians to further improve their blood loss estimation. Moreover, surgeons will then be able to choose the most accurate and user-friendly formula for more comparable data between clinical studies.

Specific Distribution within the Enterobacter cloacae Complex of Strains Isolated from Infected Orthopedic Implants

ABSTRACT Bacteria belonging to the Enterobacter genus are frequently isolated from clinical samples but are unusual causative agents of orthopedic implant infections. Twelve genetic clusters (clusters I to XII) and one sequence crowd (sequence crowd xiii) can be distinguished within the Enterobacter cloacae nomenspecies on the basis of hsp60 sequence analysis, and until now, none of these clusters could be specifically associated with a disease. In order to investigate if specific genetic clusters would be involved in infections of orthopedic material, two series of bacterial clinical isolates identified as E. cloacae by routine phenotypic identification methods were collected either from infected orthopedic implants (n = 21) or from randomly selected samples of diverse anatomical origins (control; n = 52). Analysis of the hsp60 gene showed that genetic clusters III, VI, and VIII were the most frequent genetic clusters detected in the control group, whereas cluster III was poorly represented among the orthopedic implant isolates (P = 0.006). On the other hand, E. hormaechei (clusters VI and VIII), but not cluster III, is predominantly associated with infections of orthopedic implants and, more specifically, with infected material in the hip (P = 0.019). These results support the hypothesis that, among the isolates within the E. cloacae complex, E. hormaechei and hsp60 gene sequencing-based cluster III are involved in pathogenesis in different ways and highlight the need for more accurate routine Enterobacter identification methods.

A randomised controlled trial comparing highly cross-linked and contemporary annealed polyethylene after a minimal eight-year follow-up in total hip arthroplasty using cemented acetabular components

Most published randomised controlled trials which compare the rates of wear of conventional and cross-linked (XL) polyethylene (PE) in total hip arthroplasty (THA) have described their use with a cementless acetabular component. We conducted a prospective randomised study to assess the rates of penetration of two distinct types of PE in otherwise identical cemented all-PE acetabular components. A total of 100 consecutive patients for THA were randomised to receive an acetabular component which had been either highly XL then remelted or moderately XL then annealed. After a minimum of eight years follow-up, 38 hips in the XL group and 30 hips in the annealed group had complete data (mean follow-up of 9.1 years (7.6 to 10.7) and 8.7 years (7.2 to 10.2), respectively). In the XL group, the steady state rate of penetration from one year onwards was -0.0002 mm/year (sd 0.108): in the annealed group it was 0.1382 mm/year (sd 0.129) (Mann-Whitney U test, p < 0.001). No complication specific to either material was recorded. These results show that the yearly linear rate of femoral head penetration can be significantly reduced by using a highly XLPE cemented acetabular component.

Proposition d'un protocole de suivi des infections avérées de site opératoire en chirurgie orthopédique et traumatologique

Resume Le but de cette etude a ete de decrire une methode de recensement des infections nosocomiales de site operatoire (ISO) et rapporter les resultats observes dans un service de chirurgie orthopedique et traumatologie. Le recensement de ces infections repose sur le signalement par un praticien du service de bacteriologie de tous prelevements de site operatoire ayant une culture positive. Un college de 4 medecins specialistes decide du caractere infectant du germe et de l’origine nosocomiale de l’infection. Un dossier informatique est alors cree pour chaque patient ayant une infection de site operatoire regroupant des donnees cliniques, biologiques et microbiologiques. Le fichier informatique permet alors un suivi prospectif et une analyse des cas ainsi repertories. Entre 2000 et 2002, 9397 interventions ont ete realisees et nous avons releve 86 infections de site operatoire considerees comme nosocomiales. Les patients avaient un âge moyen de 58 ans, un index de masse corporelle moyen a 25,7 et 72 % avaient un score ASA superieur ou egal a II. L’infection concernait une arthroplastie dans 23 cas, un acte de traumatologie dans 21 cas, le traitement d’une tumeur dans 24 cas. Elle a ete diagnostiquee dans les 30 jours suivant l’intervention dans 75 % des cas, et apres la sortie de l’hopital dans 65,4 % des cas. Les infections monomicrobiennes etaient les plus frequentes (n = 59) et un staphylococcus aureus a ete isole dans 80,23 % des infections. Mais en chirurgie tumorale, les infections plurimicrobiennes etaient statistiquement plus frequentes associant des staphylocoques a coagulase negatif et des bacilles Gram negatif. Nous deplorons 6 deces directement imputables a une infection de site operatoire.PURPOSE OF THE STUDY A program for the prevention of nosocomial infections, including operative site infections (OSI) is a legal obligation in France. According to the CDC, in orthopedic surgery, nosocomial infection is defined as any infection occurring within 30 days of operation, or within one year in the event of material implantation. No surveillance system has been validated and the rate of OSI is unknown in orthopedic surgery. We report the number of OSI observed during a three year period in our unit and describe the characteristic features. MATERIAL AND METHODS Data were collected from the bacteriology reports on operative site samples with a positive culture. A group of specialists determined the infective nature of the germ and the nosocomial nature of the OSI. Clinical and bacteriological data were noted on a standard datasheet used for prospective follow-up of the number of cases and data processing. During a three-year period (2000, 2001, 2002), among 9397 orthopedic and traumatology operations performed, 86 OSI were identified. Mean patient age was 58 years and mean body mass index was 25.7. The ASA score was >or=II for 72% of patients. RESULTS The OSI involved an arthroplasty in 23 cases, a traumatology procedure in 21, and tumor treatment in 24. The diagnosis was established within 30 days of operation for 75% and after discharge from hospital in 65.4%. Single-germ infections predominated (n=59). Staphylococcus aureus was isolated in 80.23% of infections. For tumor surgery, the statistically more frequent multiple-germ infections associated coagulase negative Staphylococcus and Gram-negative bacilli. There were six OSI-related deaths. DISCUSSION Two criticisms can be formulated concerning our surveillance system. First, infections with no identified germ could be missed. The frequency of such infections has been estimated at 2.8 to 19% by different authors. Although patients are automatically recalled for consultation, we were unable to determine the number of patients lost to follow-up at one year. It was thus not possible to determine a precise rate of OSI. Data in the literature have not demonstrated any system providing an exhaustive surveillance, particularly because of the long postoperative period after material implantation. Excepting tumor surgery, Staphylococcus aureus infections predominated. Factors of risk of OSI include the patients general status, particularly for arthroplasty. We had a mortality rate of 7% for our OSI, corroborating earlier studies and illustrating the severity of such infections. CONCLUSION Surveillance of OSI in orthopedic surgery requires the development of a system responding to the problem of a long observation period. It would be important to know the precise number of OSI and their characteristic features in order to develop comparison tools.

Reliability of a New Method for Evaluating Femoral Stem Positioning After Total Hip Arthroplasty Based on Stereoradiographic 3D Reconstruction

The goal of this study was to validate a new method for determining femoral stem positioning based on 3D models derived from the EOS biplanar system. Independents observers measured stem anteversion and femoral offset using CT scan and EOS system of 28 femoral stems implanted in composite femurs. In parallel, the same parameters were measured on biplanar lower limb radiographs acquired from 30 patients who had undergone total hip arthroplasty. CT scanner and biplanar X-ray measurements on composite femurs were highly correlated: 0.94 for femoral offset (P < 0.01), 0.98 for stem anteversion (P < 0.01). The inter and intra-observer reproducibility when measuring composite bones was excellent with both imaging modalities as when measuring femoral stem positioning in patients with the biplanar X-ray system.

Étude électromyographique des réflexes d’étirement intervenant au niveau de l’articulation coxo-fémorale normale et prothétique

PURPOSE OF THE STUDY: Several studies have been devoted to the effect of proprioception on joint function. Modifications in feedback control from the cord have been observed in unstable joints due to capsule and ligament laxity. A few studies have examined the effect of knee and hip arthroplasty on proprioception, but none have established whether stretch reflexes affect function of a prosthetic joint. The purpose of the present study was to demonstrate the electromyographic characteristics of stretch reflexes of the normal hip joint and to compare them with those observed in the prosthetic hip. MATERIAL AND METHODS: Two groups of patients were studied. The first included eleven subjects free of neurological disorders whose studied limb was healthy. The second group included ten subjects with a total hip prosthesis who had undergone extensive capsulectomy during the arthroplasty. Voluntary muscle contraction was noted in each subject. In addition, electromyographic recordings were made to note response of the ipsilateral and contralateral quadriceps crural and tensor of the fascia lata during changes in joint position. Recordings were made with the subject in the supine position, the limb suspended, hip flexed at 45 degrees and knee extended. Three series of ten recordings were made in random order to measure the latency of muscle response to free fall of the limb, accelerated fall of the relaxed limb, and accelerated fall associated with calibrated contraction of the quadriceps. Mean latency of muscle response was calculated for each trial. RESULTS: In the conditions of this study, there was no statistically significant difference (p = 0.05) in the reflex time course between natural and prosthetic hips. DISCUSSION: Changes due to joint replacement and capsulectomy do not appear to affect the stretch reflexes of the hip joint.

Ninety-Day Morbidity in Patients Undergoing Primary TKA With Discontinuation of Warfarin and Bridging With LMWH

We asked whether patients under long-term warfarin and managed with current guidelines regarding bridging therapy have a higher complications rate within ninety days following total knee arthroplasty. We retrospectively identified 38 patients under long-term warfarin. They were match-paired with 76 control patients. Our results showed a significant increased rate of complications (42.1% vs. 6.9%, P < 0.001) and re-operation (21.1% vs. 5.2%, P < 0.001) in the warfarin group. The difference was related to the number of hematomas requiring surgical evacuation. The warfarin group had a significantly higher rate of blood loss, blood transfusion, and length of hospital stay. Our data suggest that current guidelines for preoperative warfarin management are associated with a high rate of bleeding complications and reoperations following TKA.

82 Efficacité de la rh-BMP-7/matrice collagène (OP-1) dans la consolidation des pseudarthroses post-fracturaires

Introduction ce travail a pour objectif d’evaluer l’efficacite clinique et radiographique de la rh-BMP-7 avec une matrice collagene (OP-1, Osigraft) sur la consolidation d’une pseudarthrose post-fracturaire d’un os long. Nous souhaitons egalement evaluer le delai moyen de consolidation d’une pseudarthrose traitee par OP-1. Materiel cette etude retrospective a analyse les donnees cliniques et radiographiques pre et postoperatoires de tous les patients pris en charge dans le service pour une pseudarthrose sur fracture d’un os long entre 2001 et 2005. La serie comportait 6 pseudarthroses de jambe, une pseudarthrose de l’humerus et une pseudarthrose du femur repartis chez 4 femmes et 4 hommes. La moyenne d’âge des patients etait de 65 ans. Methode L’analyse clinique des resultats a compare les manifestations cliniques preoperatoires et au dernier recul. Les radiographies pre et postoperatoires ainsi qu’au dernier recul ont ete analysees. La consolidation osseuse etait consideree comme acquise en cas de continuite osseuse radiographique bicorticale sur deux incidences differentes (face et profil) associee a une indolence complete a l’appui. Les delais diagnostic, de prise en charge et de consolidation ont ete analyses. Le traitement de la pseudarthrose a toujours associe le traitement chirurgical habituel de la pseudarthrose (alesage, decortication-greffe, alignement et osteosynthese selon le site considere) a l’application locale d’une dose de rh-BMP-7/matrice collagene (OP-1, Osigraft). Resultats le recul radio-clinique moyen de cette serie etait de 24 mois avec un recul minimum pour chaque patient de 18 mois. La consolidation radiologique du site de pseudarthrose a ete obtenue pour tous les patients. L’indolence a l’appui a ete obtenue pour tous les patients. Le nombre moyen d’interventions avant l’application de l’OP-1 etait de 1,5. Apres cure chirurgicale de la pseudarthrose avec adjonction d’OP-1 toutes les pseudarthroses ont consolidees. Le delai moyen de consolidation apres adjonction d’OP-1 a ete de 7 mois. Nous n’avons pas constate d’ossifications ectopiques ou hypertrophiques autour du site d’application de l’OP-1. Conclusion Le traitement chirurgical habituel de la pseudarthrose d’un os long associe a l’application de rh-BMP-7/matrice collagene (OP-1) sur le site de la pseudarthrose a permit d’obtenir la consolidation en 7 mois chez tous les patients inclus dans cette serie.

Acetabular reinforcement rings associated with allograft for severe acetabular defects

Acetabular revisions with severe bone defects can be challenging procedures. Several grading systems have been set into place to help the surgeon adequately gauge the degree of bone loss within the acetabulum. Internationally innovative research in orthopedics and bio-engineering has helped with progression of successful techniques and rings to re-establish the normal anatomy of the hip. The purpose of this review is to evaluate the outcomes of the different acetabular reinforcement rings in the setting of severe acetabular defects. A successive report of relevant data from the literature of multiple techniques will be provided. The procedures include the cup-cage, the Müller ring, the Ganz Ring, the Kerboull acetabular reinforcement device (KARD), the graft augmentation prosthesis (GAP) ring, and the Burch-Schneider ring. The main focus of this overview is rings only; other devices such as trabecular augments, custom-made cages, or oblong cups are not discussed. Furthermore, a special emphasis on the surgical technique of the KARD is also given. Procedures using these rings are usually associated with bone grafts either bulk or morselized. When considering the available data on these various rings used for reconstruction of the severely damaged acetabulum, the cup-cage, the KARD, and the Burch-Schneider ring appear to be reliable options for more successful long-term outcomes.