Session III Tibia

Friday, September 27, 1996 Session III, 4:52 p.m.

*Tibial Plafond Fractures: Does Articular Reduction and/or Injury Pattern Predict Outcome?

J.L. Marsh, MD, J.V. Nepola, MD, T. Williams, MD, T. DeCoster, MD, S. Hurwitz, MD, D. Dirschell, MD

University of Iowa Hospitals and Clinics, Iowa City, IA, University of New Mexico Medical Center, Charlottesville, VA, University of North Carolina

Purpose: To determine, independently from the severity of the injury, how well the reduction of the articular surface predicts the development of radiographic arthrosis or patient outcome.

Introduction: Although articular reduction is frequently cited as the critical factor in preventing arthrosis, there is little clinical data supporting this assertion. Separating the effect of the severity of the initial injury from the effect of reduction is difficult. There is no data on the relative influence of these two factors on radiographic or clinical outcome for fractures of the tibial plafond. We have used a largely percutaneous technique which has led to a spectrum of qualities of reduction which could provide data to support or refute the importance of accurate anatomic reduction.

Methods: Due to limitations of standard classification systems with regards to interobserver reliability, a rank order method was used to stratify the severity of injury and quality of reduction. From 53 patients treated with a uniform technique of cross ankle external fixation with limited approaches for reduction of the articular surface, a subset of 25 patients with minimum two year follow-up was chosen. Cases were selected to represent a spectrum of injury severity as well as for completeness of preoperative radiographs and post-operative follow-up. Twenty-five cases were felt to be the maximum number that could be accurately ranked. Using standard three view ankle radiographs three orthopaedic traumatologists ranked [least (1) to most (25) severe] the injury in two categories; 1) articular comminution and 2) other factors felt to determine outcome. Immediate post-operative X-rays and the first films obtained with the fixator removed were employed to rank the reduction [best (1) to worst (25)] in two categories; 1) smoothness of the articular surface and 2) overall accuracy of reduction. Arthrosis was determined using three view nonweightbearing radiographs of the ankle taken at a minimum of two years after the injury. Normal x -rays, free of arthrosis were given 10 points; points were subtracted as follows: Small osteophytes -1, large osteophyte -2, joint space loss <1 mm -2, 1-2 mm -4, > 2 mm -6, cysts -1, sclerosis -1. A 100 point ankle score (modified AOFAS) was derived from a questionnaire administered to patients without prompting from the investigators.

Results: The development of arthrosis had a strong correlation to the combined effect of injury and reduction (P<.0005), but the correlation of ankle score to injury and reduction combined did not reach statistical significance (P<.11). Arthrosis and ankle score showed moderate correlation with each other (correlation coefficient of 0.64). Taken individually both injury and reduction correlated well with arthrosis (correlation coefficients 0.66 to 0.76), but not well with ankle score (correlation coefficients 0.23 and 0.45 respectively). In an univariate multiple regression model including both injury and reduction factors, the smoothness of the articular surface after reduction had the strongest influence on development of arthrosis (P<0.04).

Discussion: The dogma that restoration of articular congruity is necessary to prevent arthrosis is simplistic and does not account for all the factors that portend a satisfactory outcome for a severe articular fracture. The severity of the initial injury has an effect on the development of arthrosis. Surgeons should be aware of the factors under their control that are most likely to predict patient outcome in these severe fractures. These results should be interpreted with the knowledge that all fractures in this series had some reduction and none were left to heal in their injury position.