Peter Wahl

Diagnosis of periprosthetic joint infection

Liaison: Benjamin Zmistowski BS Leaders: Craig Della Valle MD (US), Thomas W Bauer MD (US), Konstantinos N. Malizos MD, PhD (International) Delegates: Abbas Alavi MD, Hani Bedair MD, Robert E Booth MD, Peter Choong MD, Carl Deirmengian MD, Garth D Ehrlich PhD, Anil Gambir MD, Ronald Huang MD, Yair Kissin MD, Hideo Kobayashi MD, Naomi Kobayashi MD, Veit Krenn MD, Drago Lorenzo MD, SB Marston MD, Geert Meermans MD, Javier Perez MD, JJ Ploegmakers MD, Aaron Rosenberg MD, C Simpfendorfer MD, Peter Thomas MD, Stephan Tohtz MD, Jorge A Villafuerte MD, Peter Wahl MD, Frank-Christiaan Wagenaar MD, Eivind Witzo MD

Acute isolated injury of the posterior cruciate ligament treated by a dynamic anterior drawer brace: A PRELIMINARY REPORT

We investigated the role of a functional brace worn for four months in the treatment of patients with an acute isolated tear of the posterior cruciate ligament to determine whether reduction of the posterior tibial translation during the healing period would give an improved final position of the tibia. The initial and follow-up stability was tested by Rolimeter arthrometry and radiography. The clinical outcome was evaluated using the Lysholm score, the Tegner score and the International Knee Documentation Committee scoring system at follow-up at one and two years. In all, 21 patients were studied, 21 of whom had completed one-year and 17 a two-year follow-up. The initial mean posterior sag (Rolimeter measurement) of 7.1 mm (5 to 10) was significantly reduced after 12 months to a mean of 2.3 mm (0 to 6, p < 0.001) and to a mean of 3.2 mm (2 to 7, p = 0.001) after 24 months. Radiological measurement gave similar results. The mean pre-injury Lysholm score was normal at 98 (95 to 100). At follow-up, a slight decrease in the mean values was observed to 94.0 (79 to 100, p = 0.001) at one year and 94.0 (88 to 100, p = 0.027, at two years). We concluded that the posterior cruciate ligament has an intrinsic healing capacity and, if the posteriorly translated tibia is reduced to a physiological position, it can heal with less attentuation. The applied treatment produces a good to excellent functional result.

Association Between Mechanical Axis of the Leg and Osteochondritis Dissecans of the Knee Radiographic Study on 103 Knees

Background: The cause of osteochondritis dissecans (OCD) is unknown, but mechanical factors seem to play a role. Purpose: To identify a relationship between localization of OCD and mechanical axis of the leg. Study Design: Case series; Level of evidence, 4. Methods: Using bilateral full-leg standing radiographs, we analyzed the position of the mechanical axis of the leg in a group of 93 adolescent and adult patients (103 knees) with OCD of the medial or lateral femoral condyle. Results: The location of OCD and the position of the mechanical axis in the same knee compartment was significantly correlated for both knees with medial (P < .001) as well as lateral (P < .012) compartment OCD. In the medial OCD group, the mean mechanical axis was located in the medial knee compartment (28% medial ± 2.8%; range, 100% medial to 14% lateral) with a statistically insignificant medial shift with respect to the unaffected side. In lateral OCD, the mean mechanical axis was located laterally (13% lateral ± 3.9%; range, 13% medial to 60% lateral) with a significant shift from the medial into the lateral knee compartment when comparing unaffected with affected knees. No significant difference was observed between adolescents with open growth plates compared with adults with closed growth plates (P > .05). Conclusion: We found an association between medial condyle OCD and varus axis and between lateral condyle OCD and valgus axis. This evokes higher loading of the affected than of the unaffected knee compartment, and therefore, axial alignment may be a cofactor in OCD of the femoral condyles.

Avoiding intraoperative complications in open-wedge high tibial valgus osteotomy: technical advancement

Open-wedge high tibial osteotomy for varus osteoarthritis of the knee is a successful treatment option, but is associated with potential intraoperative complications, jeopardizing outcome. We describe four technical hints avoiding complications as tibia plateau fracture, lateral hinge dislocation, over- and undercorrection, and unwanted increase of the posterior tibial slope and axial malrotation. The technique, which is primarily based on placing five Kirschner-wires (one for the osteotomy direction, two for the external fixator, and two for rotational and slope control) is simple, reproducible, inexpensive, and readily available.

Phenotypic and genotypic characterisation of Staphylococcus aureus causing musculoskeletal infections.

One of the most common pathogens causing musculoskeletal infections remains Staphylococcus aureus. The aim of this multicentre study was to perform a phenotypic and genotypic characterisation of clinical S. aureus isolates recovered from musculoskeletal infections and to investigate differences between isolates cultured from Orthopaedic Implant Related Infections (OIRI) and those from Non-Implant Related Infections (NIRI). OIRI were further differentiated in two groups: Fracture Fixation-Device Infections (FFI) and Prosthetic Joint Infections (PJI). Three-hundred and five S. aureus strains were collected from 4 different Swiss and 2 French hospitals (FFI, n=112; PJI, n=105; NIRI, n=88). NIRI cases were composed of 27 Osteomyelitis (OM), 23 Diabetic Foot Infections (DFI), 27 Soft Tissue Infections (STI) and 11 postoperative Spinal Infections (SI). All isolates were tested for their ability to form biofilm, to produce staphyloxanthin and their haemolytic activity. They were typed by agr (accessory gene regulator) group, spa type and screened by PCR for the presence of genes of the most relevant virulence factors such as MSCRAMMs, Panton Valentine Leukotoxin (PVL), enterotoxins, exotoxins and toxic shock syndrome toxin. Overall, methicillin susceptible S. aureus (MSSA) was more prevalent than methicillin resistant S. aureus (MRSA) in this collection. The OIRI group trended towards a higher incidence of MRSA, gentamicin resistance and haemolysis activity than the NIRI group. Within the OIRI group, PJI isolates were more frequently strong biofilm formers than isolates from the FFI group. A statistically significant difference was observed between OIRI and NIRI isolates for the sdrE gene, the cna gene, the clfA gene and the bbp gene. Certain spa types (t230 and t041) with a specific genetic virulence pattern were only found in isolates cultured from OIRI. In conclusion, our study highlights significant trends regarding the virulence requirements displayed by S. aureus isolates associated with implant related infections in comparison to non-implant related infections. However, future studies including whole genome sequencing will be required to further examine genomic differences among the different infection cases.

Optimal Culture Incubation Time in Orthopedic Device-Associated Infections: a Retrospective Analysis of Prolonged 14-Day Incubation

ABSTRACT Accurate diagnosis of orthopedic device-associated infections can be challenging. Culture of tissue biopsy specimens is often considered the gold standard; however, there is currently no consensus on the ideal incubation time for specimens. The aim of our study was to assess the yield of a 14-day incubation protocol for tissue biopsy specimens from revision surgery (joint replacements and internal fixation devices) in a general orthopedic and trauma surgery setting. Medical records were reviewed retrospectively in order to identify cases of infection according to predefined diagnostic criteria. From August 2009 to March 2012, 499 tissue biopsy specimens were sampled from 117 cases. In 70 cases (59.8%), at least one sample showed microbiological growth. Among them, 58 cases (82.9%) were considered infections and 12 cases (17.1%) were classified as contaminations. The median time to positivity in the cases of infection was 1 day (range, 1 to 10 days), compared to 6 days (range, 1 to 11 days) in the cases of contamination (P < 0.001). Fifty-six (96.6%) of the infection cases were diagnosed within 7 days of incubation. In conclusion, the results of our study show that the incubation of tissue biopsy specimens beyond 7 days is not productive in a general orthopedic and trauma surgery setting. Prolonged 14-day incubation might be of interest in particular situations, however, in which the prevalence of slow-growing microorganisms and anaerobes is higher.

Systemic exposure to tobramycin after local antibiotic treatment with calcium sulphate as carrier material

IntroductionOsteoset® T is a calcium sulphate void filler containing 4% tobramycin sulphate, used to treat bone and soft tissue infections. Despite systemic exposure to the antibiotic, there are no pharmacokinetic studies in humans published so far. Based on the observations made in our patients, a model predicting tobramycin serum levels and evaluating their toxicity potential is presented.MethodsFollowing implantation of Osteoset® T, tobramycin serum concentrations were monitored systematically. A pharmacokinetic analysis was performed using a non-linear mixed effects model based on a one compartment model with first-degree absorption.ResultsData from 12 patients treated between October 2006 and March 2008 were analysed. Concentration profiles were consistent with the first-order slow release and single-compartment kinetics, whilst showing important variability. Predicted tobramycin serum concentrations depended clearly on both implanted drug amount and renal function.Discussion and conclusionDespite the popularity of aminoglycosides for local antibiotic therapy, pharmacokinetic data for this indication are scarce, and not available for calcium sulphate as carrier material. Systemic exposure to tobramycin after implantation of Osteoset® T appears reassuring regarding toxicity potential, except in case of markedly impaired renal function. We recommend in adapting the dosage to the estimated creatinine clearance rather than solely to the patient’s weight.

Vancomycin displays time‐dependent eradication of mature Staphylococcus aureus biofilms

This study was carried out to determine the time and concentration profile required to achieve vancomycin‐mediated eradication of Staphylococcus aureus biofilm. This information is critical for the identification of performance targets for local antibiotic delivery vehicles that target biofilm infections. S. aureus UAMS‐1 biofilms were grown for 7 days on titanium–aluminium–niobium discs in Mueller Hinton broth. After 7 days, the discs were then incubated in Mueller Hinton broth containing vancomycin at concentrations of 100, 200, 500, 1,000, and 2,000 mg/L. Biofilm eradication was assessed under both static and shaking conditions. Samples were retrieved at regular intervals for up to 28 days for quantification of residual biofilm. One additional disc was processed per time point for scanning electron microscopy. Progressive and significant reduction of viable bacteria was observed over time at all concentrations compared to unexposed controls. After 28 days under static conditions, the S. aureus biofilm was completely eradicated at 200 mg/L vancomycin and higher concentrations, but not at 100 mg/L. In contrast, bacterial biofilm could not be eradicated under shaking conditions at any concentration.

Repositioning and stabilization of the radial styloid process in comminuted fractures of the distal radius using a single approach: the radio-volar double plating technique

BackgroundA possible difficulty in intra-articular fracture of the distal radius is the displacement tendency of the radial styloid process due to the tension of the brachioradialis tendon.MethodsTen patients treated within one year for complex distal radius fractures by double-plating technique with a radial buttress plate and volar locking plate, through a single volar approach, were followed prospectively during 24 months. Outcome measures included radiographic follow-up, range of motion, grip strength and score follow-up (VAS, Gartland-Werley score and patient-rated wrist evaluation).ResultsTen patients with intraarticular distal radius fractures with dislocation of the radial styloid process were treated with this technique. This resulted after 24 months in good clinical outcome (mean visual analog scale 0.9; almost symmetric range of motion; mean Gartland-Werley score 2 ± 3; mean patient-rated wrist evaluation 3.2 ± 2.4). Radiologic evaluation according to the Dresdner Score revealed anatomic reduction without secondary dislocation during the follow-up and uneventful consolidation.ConclusionsThe described technique strongly facilitates anatomic reduction and stable fixation of intra-articular distal radius fractures with dislocation of the radial styloid process and leads to satisfactory clinical and radiographic outcome.

Treatment of Discogenic Low Back Pain by Total Disc Arthroplasty using the Prodisc Prosthesis: Analysis of a Prospective Cohort Study with Five- Year Clinical Follow-Up

Few studies are available for the long-term outcome of disc arthroplasty using the Prodisc prostheses. We evaluated if total disc arthroplasty using the Prodisc prosthesis could be a reliable treatment for disabling low-back pain, and if long lasting improvement in quality-of-life could be achieved. We hypothesized that analysis of a prospective cohort study with a mean 5-year follow-up, clinical control, done by rheumatologists not involved in treatment would provide data that was not influenced by surgeon bias. Thirty-nine patients undergoing disc replacement between May 2002 and July 2004 were the study population. Fifty-two levels from L2 to S1, of which 28 were single-level, 9 were double-level and two were three levels, were treated. Independent clinical evaluation by uninvolved rheumatologists was done preoperatively at 1, 2 and 5 years after surgery. The Visual Analogue Score (VAS) for leg and lumbar pain intensity, Oswestry Low Back Pain Disability Index (ODI), Short Form-36 (SF-36), patient satisfaction, and the return to work rate were assessed. Analysis revealed a significant amelioration of the VAS for back and leg pain, as well as for the ODI and the SF-36. Since this is a motion preservation device study it is important to include range of motion ROM analysis at the follow-up times. These data suggest that total disc arthroplasty using the prodisc prosthesis is a good treatment option for disabling discogenic low back pain. The improvement achieved after 1 year could be conserved at 2- and 5-year follow