Rami Madanat

Risk factors for deep surgical site infection following operative treatment of ankle fractures.

BACKGROUND Surgical site infection is one of the most common complications following ankle fracture surgery. These infections are associated with substantial morbidity and lead to increased resource utilization. Identification of risk factors is crucial for developing strategies to prevent these complications. METHODS We performed an age and sex-matched case-control study to identify patient and surgery-related risk factors for deep surgical site infection following operative ankle fracture treatment. We identified 1923 ankle fracture operations performed in 1915 patients from 2006 through 2009. A total of 131 patients with deep infection were identified and compared with an equal number of uninfected control patients. Risk factors for infection were determined with use of conditional logistic regression analysis. RESULTS The incidence of deep infection was 6.8%. Univariate analysis showed diabetes (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.0, 4.9), alcohol abuse (OR = 3.8, 95% CI = 1.6, 9.4), fracture-dislocation (OR = 2.0, 95% CI = 1.2, 3.5), and soft-tissue injury (a Tscherne grade of ≥1) (OR = 2.6, 95% CI = 1.3, 5.3) to be significant patient-related risk factors for infection. Surgery-related risk factors were suboptimal timing of prophylactic antibiotics (OR = 1.9, 95% CI = 1.0, 3.4), difficulties encountered during surgery, (OR = 2.1, 95% CI = 1.1, 4.0), wound complications (OR = 4.8, 95% CI = 1.6, 14.0), and fracture malreduction (OR = 3.4, 95% CI = 1.3, 9.2). Independent risk factors for infection identified by multivariable analyses were tobacco use (OR = 3.7, 95% CI = 1.6, 8.5) and a duration of surgery of more than ninety minutes (OR = 2.5, 95% CI = 1.1, 5.7). Cast application in the operating room was independently associated with a decreased infection rate (OR = 0.4, 95% CI = 0.2, 0.8). CONCLUSIONS We identified several modifiable risk factors for deep surgical site infection following operative treatment of ankle fractures.

Predictors of poor outcomes following deep infection after internal fixation of ankle fractures.

The development of deep infection following operative treatment of ankle fractures can have catastrophic consequences. The aim of this study was to identify factors predisposing to treatment failure of an infected ankle fracture. Out of 1923 consecutive ankle fracture operations we identified 97 patients with deep infection necessitating at least one surgical debridement. The outcome measure was a clinical failure or success of the treatment. Various parameters considered to predict clinical outcome were evaluated. Treatment failure occurred in 27% of patients with deep infection necessitating surgical debridement. The mean age of these patients was 54 years and the mean follow-up time was 22 months. The variables that were independently associated with an increased risk of treatment failure included smoking, postoperative malreduction, hardware removal from an ununited fracture and the need for two or more additional debridements. Other significant risk factors included diabetes, alcohol abuse, high-energy injury, Danis-Weber type C fracture, multibacterial infection and ununited fracture at debridement. Our study showed that smoking, postoperative malreduction and hardware removal prior to fracture union were the most important factors predisposing to a permanent complication following an ankle fracture infection. We recommend that hardware be removed only after fracture union has been confirmed.

Factors predicting the development of early osteoarthritis following lateral tibial plateau fractures: mid-term clinical and radiographic outcomes of 73 operatively treated patients.

Background and Aims: The indications for operative treatment of lateral tibial plateau fractures are still controversial. The objective of this study was to determine whether residual articular surface depression and valgus malalignment of plated lateral tibial plateau fractures at medium-term follow-up affect the clinical and radiographic outcomes. Material and Methods: A chart review of patients with operatively treated (AO type B3.1) tibial plateau fractures that were admitted to our level I trauma center between 2002 and 2008 was performed. Out of 123 patients, 73 were available to participate in a clinical and radiographic follow-up examination. The mean follow-up time was 54 months. Patients were clinically assessed and completed the Lysholm knee score and Western Ontario and McMaster Universities Osteoarthritis Index. Maximal articular surface depression, radiological mechanical axis, and degree of posttraumatic osteoarthritis were evaluated from standing radiographs. Results: Patients with valgus malalignment of 5° or greater at follow-up developed more advanced osteoarthritis (Kellgren–Lawrence grade 3–4) than patients with a normal mechanical axis (p = 0.006). Similarly, patients with articular depression greater than 2 mm at follow-up also developed more advanced osteoarthritis compared to patients with a depression of 2 mm or less (p = 0.001). The degree of valgus malalignment or articular depression had no effect on the Western Ontario and McMaster Universities Osteoarthritis Index or Lysholm scores. Conclusions: The postoperative articular congruity and normal mechanical axis of the lower leg after plate fixation in lateral tibial plateau fractures seem to have a role in prevention of posttraumatic osteoarthritis but does not appear to predict clinical outcome at medium-term follow-up. The role of initial dislocation and associated cartilage damage in the development of osteoarthritis following these fractures is still unknown.

RSA Applications in Monitoring of Fracture Healing in Clinical Trials

Radiostereometric analysis (RSA) was originally developed as a method for performing highly accurate three-dimensional measurements in vivo over time from sequential radiographs. Since its introduction over twenty years ago, the RSA method has proven itself as a powerful tool with numerous orthopaedic applications. RSA has been used extensively in studies of prosthetic fixation and has been shown to be the method of choice for these studies. RSA has, however, also been successfully applied to a limited number of studies examining fracture healing, namely in fractures of the radius, ankle, tibial plateau, trochanter and femoral neck, as well as studies of bone healing following spinal fusion and tibial osteotomies. RSA follow-up of a fracture will provide definitive demonstration of the exact time of union, i.e. the achievement of fracture stability. This information can be invaluable in randomized clinical trials of fracture treatment. Phantom model studies have proven useful for effective preoperative planning and interpretation of RSA results. The RSA method is a highly accurate, precise and safe objective method for studying fracture healing in clinical trials. The RSA method may serve as a scientific tool to accurately evaluate the significance of supporting novel biomaterials for the early stability and the rate of healing in fractures.

Dislocation of hip hemiarthroplasty following posterolateral surgical approach: a nested case–control study

PurposeHip hemiarthroplasty dislocation is a serious complication in treatment of displaced intracapsular hip fractures. We investigated factors associated with an increased risk of dislocation after cemented hip hemiarthroplasty following the posterolateral approach.MethodsBetween January 2002 and December 2008, 602 hip fractures were treated with cemented unipolar hip hemiarthroplasty. A registry-based analysis was carried out to determine the total number of hemiarthroplasty dislocations in these patients. A control group of 96 patients without dislocation was randomly selected. Logistic regression analysis was performed to evaluate clinical and operative factors associated with dislocation.ResultsThirty-four patients (5.6%) experienced at least one dislocation. Most were the result of a fall and occurred within two months after surgery. There was a trend for increased dislocation in patients who had been operated on more than 48 hours after admission and in patients who had a longer operative time. Smaller centre-edge angle and hip offset were observed in patients with dislocation. Recurrent dislocation was a significant problem, as 18 patients (62%) experienced multiple dislocations.ConclusionsThe risk of hemiarthroplasty dislocation following the posterolateral surgical approach may be reduced by prompt surgical treatment and fall prevention in the early postoperative period. Patients with smaller acetabular coverage seem more predisposed to dislocation after the posterolateral approach and may be more suitable for other surgical approaches.

Radio-opaque bioactive glass markers for radiostereometric analysis

The objective of the study was to test the hypothesis that resorbable radio-opaque bioactive glass markers can be used in radiostereometric analysis (RSA). Cones made from (1) bioactive glass 1-06 with 2.5 wt.% BaSO(4), (2) glass 1-06 with 10 wt.% BaSO(4), (3) glass 1-06 without any additives and (4) nearly inert glass were created. The in vitro surface reactivity, as a surrogate of bioactivity, was analyzed using a simulated body fluid (SBF) immersion test. The in vivo performance was evaluated in the rat femur using biomechanical testing as well as histological and microcomputed tomography analysis of marker incorporation into bone. A phantom model RSA study using a porcine radius with a soft tissue envelope was carried out to determine the accuracy and precision of spherical markers for the measurement of fracture micromotion. SBF immersion studies and bone implantation studies showed that the addition of BaSO(4) slightly reduced surface reactivity in vitro and the bone-bonding properties of the bioactive glass in vivo. In the simulated RSA study with the selected resorbable marker composition (bioactive glass with 10 wt.% BaSO(4)), the accuracy of translation and rotation measurements in the longitudinal axis was +/-51 microm and +/-0.87 degrees , respectively. The precision of translation and rotation measurements in the longitudinal axis were 9 microm and 0.18 degrees , respectively. Bioactive glass markers with BaSO(4) additive appear to have adequate bone-bonding properties for marker stability and sufficient radio-opacity for RSA, but further preclinical comparison studies with tantalum markers are necessary.

Adherence of hip and knee arthroplasty studies to RSA standardization guidelines: A systematic review

Background and purpose — Guidelines for standardization of radiostereometry (RSA) of implants were published in 2005 to facilitate comparison of outcomes between various research groups. In this systematic review, we determined how well studies have adhered to these guidelines. Methods — We carried out a literature search to identify all articles published between January 2000 and December 2011 that used RSA in the evaluation of hip or knee prosthesis migration. 2 investigators independently evaluated each of the studies for adherence to the 13 individual guideline items. Since some of the 13 points included more than 1 criterion, studies were assessed on whether each point was fully met, partially met, or not met. Results — 153 studies that met our inclusion criteria were identified. 61 of these were published before the guidelines were introduced (2000–2005) and 92 after the guidelines were introduced (2006–2011). The methodological quality of RSA studies clearly improved from 2000 to 2011. None of the studies fully met all 13 guidelines. Nearly half (43) of the studies published after the guidelines demonstrated a high methodological quality and adhered at least partially to 10 of the 13 guidelines, whereas less than one-fifth (11) of the studies published before the guidelines had the same methodological quality. Commonly unaddressed guideline items were related to imaging methodology, determination of precision from double examinations, and also mean error of rigid-body fitting and condition number cutoff levels. Interpretation — The guidelines have improved methodological reporting in RSA studies, but adherence to these guidelines is still relatively low. There is a need to update and clarify the guidelines for clinical hip and knee arthroplasty RSA studies.

Radiostereometric analysis in measurements of migration and inducible micromotion in intra-articular distal radius fractures treated with a volar plate.

Objectives: This study examined the use of radiostereometric analysis (RSA) in the assessment of fixation stability and healing characteristics in intra-articular fractures of the distal radius treated with a volar locking plate. Design: Prospective cohort study. Setting: University hospital. Patients: Fifteen patients between 39 and 67 years of age with OTA type C distal radius fractures. Intervention: All fractures were treated with a locked volar plate, and tantalum markers were inserted into fracture fragments. RSA was performed at 2, 6, 12, 18, and 52 weeks postoperatively. RSA measurements were also performed using maximal voluntary grip to create inducible micromotion at the fracture site at 6, 12, 18, and 52 weeks. Main Outcome Measurements: Interfragmentary migration and inducible micromotion in terms of translation and rotation in 3 orthogonal axes were determined. The total translation and rotation were also calculated. Results: Precision of measurements along individual axes was between 0.08 and 0.17 mm and 0.70–0.94 degrees for migration and between 0.04 and 0.07 mm and 0.29 and 0.86 degrees for inducible micromotion. Fractures underwent significant translational and rotational migration (P = 0.004 for both) during the first 2 weeks after surgery. This permanent migration was not detectable on conventional radiographs. Inducible fracture micromotion, measured during maximal grip, was detectable up to 18 weeks, even after achievement of radiographic union. Conclusions: RSA seems to have the potential to be a unique tool in redefining the biologic progress of fracture union. In plated fractures of the distal radius, the method is technically challenging due to difficulties in achieving a good scatter and visibility of tantalum RSA markers. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

S-27 Radiostereometric Analysis Detects Interfragmentary Micromotion in Healed Intra-Articular Fractures of the Distal Radius Treated with a Volar Locking Plate

A large number of different volar plate designs have emerged into the market without evidence-based data on their relative efficacy in the stabilization of unstable fractures of the distal end of the radius. One of the obstacles is the lack of suitable methods for quantitative assessment of fracture union. The aim of this study was to perform a critical evaluation of radiostereometric analysis (RSA) in the measurement of three-dimensional interfragmentary micromotion in patients with intra-articular fractures of the distal radius treated with a volar locking plate. Fifteen consecutive adult patients with AO type-C fractures of the distal end of the radius were recruited into the study. All fractures were treated with one type of volar fixed-angle plate. During operative treatment, tantalum RSA markers were inserted into proximal and distal fracture fragments of the radius. Assessment of the treatment outcome included functional tests, Patient-Rated Wrist Evaluation questionnaire (PRWE), conventional radiography and static RSA imaging performed at two, six, twelve, eighteen, and fifty-two weeks postoperatively. In order to study inducible interfragmentary micromotion, dynamic RSA imaging was performed during maximal voluntary grip at the follow-up visits starting at six weeks. Interfragmentary migration and inducible micromotion were measured for three axes of translation and rotation, and the total translation and rotation were calculated. The precision of measurements along individual axes was between 0.08–0.17mm and 0.70–0.94° for migration and between 0.04– 0.07mm and 0.29–0.86° for inducible micromotion. The fractures underwent significant translational and rotational migration (p =0.004 for both) during the first two weeks after surgery, but not thereafter. Maximal grip caused significant translational and rotational interfragmentary micromotion (p < 0.03 for both). Inducible micromotion was detectable up to eighteen weeks even after achievement of radiographic union. Application of RSA in the measurement of fracture fragment migration and inducible interfragmentary micromotion is feasible but technically demanding. RSA may be a unique tool for randomized clinical trials in defining the progress of fracture union.