Predicting the need for collateral ligament repair in transolecranon fractures of the elbow: a traffic light model.

BACKGROUND: Biomechanical studies have shown translation of the proximal radius relative to the capitellum in the sagittal plane can predict integrity of the collateral ligaments in a transolecranon fracture model; no studies have examined this in clinical practice.

METHODS & MATERIALS: Nineteen consecutive transolecranon fracture dislocations were retrospectively reviewed. Data collection included: patient demographics, fracture classifications, surgical management and failure with instability. Distance between the center of the radial head and the center of the capitellum was measured on initial radiographs by two independent raters on three separate occasions. Statistical analysis was used to compare the median displacement between patients who required collateral ligament repair for stability and those who did not.

RESULTS: Sixteen cases with a mean age of 57 years (32-85) were analyzed with an inter-rater Pearson coefficient of 0.89 for displacement measurement. Median displacement where collateral ligament repair was needed and performed was 17.13mm (IQR=10.43-23.88) compared with 4.63mm (IQR=2.68-6.58) where collateral ligament repair was not performed and not required; p=0.002. In 4 cases, ligament repair was not performed initially but deemed necessary based on clinical outcome, postoperative and intra-operative images. Of these, the median displacement was 15.59mm (IQR=10.09-21.20) and 2 of these required revision fixation.

DISCUSSION: Where displacement on initial radiographs exceeded 10mm, LUCL repair was required in all cases (red group). If less than 5mm, ligament repair was not required in any case (green group). Between 5-10mm, following fracture fixation, the elbow must be screened carefully to assess for any instability and a low threshold set for LUCL repair to prevent posterolateral rotatory instability (amber group). Using these findings, we propose a traffic light model to predict the need for collateral ligament repair in transolecranon fractures and dislocation.