Predrilled locking compression plate is more accurate than tension band wiring in restoring articular geometry of the ulnar greater sigmoid notch after olecranon Chevron osteotomy.

INTRODUCTION

The olecranon Chevron osteotomy (OCO) is commonly used to approach complex intra-articular fractures of the distal humerus. Predrilled tension band wiring (TBW) has historically been used to fix OCO. However, clinical outcomes are burdened by secondary loss of reduction and up to 21.3% non-union rates. The biomechanical stability of anatomic locking compression plate (LCP) was reported to be superior to TBW in olecranon fracture fixation. We hypothesised that this implant may also be superior to TBW in the anatomic reconstruction of the articular surfaces of the ulnar greater sigmoid notch after OCO by predrilling the holes of the angular stable plate with the threaded drill guide prior to osteotomy.

MATERIALS AND METHODS

Lateral standardised and calibrated radiographs of twenty synthetic ulnar bones were obtained using a custom-made holder prior to preparation by a senior orthopaedic trauma surgeon. Ten specimens were then predrilled using the threaded drill bit guide of an olecranon LCP, while the other ten samples were predrilled with two 1.6 mm Kirschner wires. A distal "V" OCO was performed using a 0.6 mm oscillating saw. After repositioning and fixation with the corresponding device, lateral radiographs were repeated. Two independent observers used the TraumaCad planning software to document the articular geometry of the ulnar greater sigmoid notch pre- and postoperatively. The diameter of the best-fitting circle (diameter), the distance between the tip of the coronoid and the olecranon processes (distance) and the maximum articular depth were measured.

RESULTS

With the TBW technique, after OCO and fixation, all three postoperative measurements were significantly (p≤0.001) different from preoperative measurements. The diameter and distance increased by a mean of 1.5±0.5 mm and 0.9±0.3 mm, respectively, while the depth decreased by a mean of 0.2±0.1 mm. In contrast, no significant differences between pre- and postoperative measurements were observed with the LCP technique (p≥0.13). Inter and intra-observer measurement reliability was strong to very strong (intraclass correlation coefficients≥0.793) for all three variables.

CONCLUSION

Our study reveals that the predrilled LCP technique is more accurate than the predrilled TBW in restoring the anatomic articular geometry of the ulnar greater sigmoid notch after OCO.