Does a Patient’s Self-Reported Ability to Weightbear Immediately after Injury Predict Stability for Ankle Fractures

Category: Trauma Introduction/Purpose: Determining the stability of ankle fractures, particularly for apparent isolated Weber B fibula fractures, can be difficult. While the ultimate goal remains achieving an anatomic mortise, different techniques to predict ankle stability such as stress and weightbearing radiographs have been utilized with variable results. History of injury and the ability to walk after sustaining ankle trauma may be predictive of stability. Therefore, this study seeks to determine whether a patient’s ability to fully weight bear immediately after injury is an effective indicator for ankle stability following ankle fracture. Methods: A prospective review was conducted of patients sustaining isolated, unilateral ankle fractures presenting to two level I trauma centers. Aside from demographic data and fracture characteristics, a patient’s ability or inability to fully weightbear immediately after injury was elicited by interview at their initial assessment. This information was correlated with their ankle radiographs, which were deemed stable or unstable fractures based on commonly used indices to assess ankle stability. Results: 102 consecutive patients sustaining ankle fractures were included. Mean age was 45. When analyzing the entire cohort, patients who were able to ambulate immediately after injury were 10 times more likely to have a stable ankle fracture than those who could not bear weight (odds ratio (OR) 9.9 (P < 0.001). The positive predictive value (PPV) for being able to fully weightbear as it relates to a stable ankle fracture was 77%. Additionally, inability to weightbear was 89% specific for an unstable fracture. When separately analyzing patients with apparent isolated fibula fractures (n=56), the PPV was 75%, specificity was 83%, while the OR was 5.8 (p=0.003) for those who could fully bear weight having a stable ankle fracture. Conclusion: This study demonstrates that patient’s self-reported ability to fully weightbear immediately after injury is a specific and convenient prognostic indicator for ankle stability across a range of ankle fracture subtypes. Future studies can analyze whether initial weightbearing accurately predicts ultimate management and good outcome

Consideration of Medial Anatomical Structures at Risk when Placing Quadricortical Syndesmotic Fixation

Category: Trauma Introduction/Purpose: Surgical fixation of ankle fractures with syndesmotic instability using quadricortical fixation through the fibula and tibia is commonly performed to maintain mortise congruency. Quadricortical fixation can be achieved by screws or suture buttons however both involve unprotected drilling and placement of hardware through the medial distal tibia which places anatomic structures at iatrogenic risk. These structures may include the anterior tibialis tendon, the saphenous neurovascular bundle (SNVB) and posteriorly, the posterior tibialis tendon (PTT). This study aims to radiographically map the anatomic course of these structures at risk on a lateral radiograph as would be used intraoperatively during syndesmotic fixation. Methods: Eighteen fresh-frozen cadaveric feet were dissected with preservation of all soft tissue and neurovascular structures over the medial distal tibia. While preserving fascial and tendinous sheath attachments, the SNVB and the PTT were identified and marked with metal wiring. Standardized and calibrated lateral radiographs were obtained to determine the anatomic course of these structures. Lateral radiographs of the distal tibia and fibula were analyzed by a grid system comprised of 1 cm row-increments moving cranially from the ankle joint up to 5 cm and by 3 evenly distributed parallel columnar zones from anterior to posterior (see Figure). The anterior boundary of the columnar zone was placed at the anterior tibial shaft and the posterior boundary was placed at the posterior malleolus of the tibia. The position of respective metal wires placed within the SNVB and the anterior portion of the PTT were charted according to this grid system and results compiled. Results: The SNVB was located in zone 1 or 2 (or anterior to zone 1) in 97.3% of specimens (107/110). The SNVB traversed from proximal-posterior to distal-anterior. For the 16 specimens that crossed a columnar zone, the most common crossover was from zone 2 to zone 1 at 3-4 cm above the ankle joint which occurred in 43.8% (7 of 16) specimens. The PPT was found in zone 3 in all specimens (n=18) with only one specimen demonstrating crossover of a columnar zone into zone 2 at its most distal extent (0-1 cm). The PTT was noted to pass behind (radiographically overlap) with the tibia in 83.3% (15 of 18) of specimens between 1 and 3 cm above the ankle joint. Conclusion: Inappropriate placement of quadricortical syndesmotic fixation may place structures on the medial ankle at risk given blind drilling and hardware placement. The SNVB is at considerable risk along the anterior course of the distal tibial while the PTT is only at risk in zone 3 at the distal extent of the tibia when a true lateral radiograph is obtained. This grid system allows a simple intra-operative check to guide safer placement of quadricortical syndesmotic fixation

High Variability of Observed Weight Bearing During Standing Foot and Ankle Radiographs

Category: Basic Sciences/Biologics, Trauma Introduction/Purpose: Weight bearing radiographs are a critical component of evaluating foot and ankle pathology. An underlying assumption is that patients are placing 50% of their body weight on the affected foot during image acquisition. The accuracy of weight bearing during radiographs is unknown and, presumably, variable, which may result in uncertain ability of the resultant radiographs to accurately portray the pathology of interest. Methods: 50 subjects were tested. The percent body weight through the foot of interest was measured at the moment of radiographic image acquisition. The subject was then instructed to “bear ½ body weight” prior to the next radiograph. The percent body weight was calculated and compared to ideal 50% weight bearing. Results: The mean percent body weight in trial 1 and 2 was 45.7% ± 3.2% (p=0.012 compared to 50% mark) and 49.2% ± 2.4%, respectively (p=0.428 compared to 50%). The mean absolute difference in percent weight bearing compared to 50% in trials 1 and 2 was 9.3% ± 2.25% and 5.75% ± 1.8%, respectively (p=0.005). For trial 1, 18/50 subjects were within the “ideal” (45-55%) range for weight bearing compared to 32/50 on trial 2 (p=0.005). In trial 1 24/50 subjects had “appropriate” (>45%) weight bearing compared to 39/50 on trial 2 (p=0.002). Conclusion: There is substantial variability in the weight applied during radiograph acquisition. This study raises significant questions about assumptions we, as orthopaedic surgeons, have made regarding weight bearing radiographs, their reliability and how we should proceed when evaluating them

Overtightening of the Syndesmosis Revisited and the Effect of Syndesmotic Malreduction on Ankle Dorsiflexion

Category: Ankle, Trauma Introduction/Purpose: Ankle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws. The purposes of the current investigation are: To assess the effect of syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of ankle dorsiflexion. To assess the effect of anterior & posterior syndesmotic malreduction after syndesmotic screw fixation on ankle dorsiflexion. Methods: Fifteen cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro- sensor system after application of a consistent load in the intact state, after compression fixation with a syndesmotic screw and after anterior & posterior malreduction of the syndesmosis. Results: Following screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7±0.87% (mean ± standard error) of baseline ankle ROM. Anterior and posterior displacement of the syndesmosis resulted in dorsiflexion ROM that was 99.1±1.75% and 98.6±1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value =0.88). Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value= 0.99). Conclusion: Maximal dorsiflexion of the ankle is not required prior to syndesmotic fixation. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation has no effect on ankle dorsiflexion thus poor patient outcomes after syndesmotic malreduction does not appear to be the result of loss of dorsiflexion due to mechanical block