Acute Shortening Versus Bridging Plate for Highly Comminuted Olecranon Fractures
Severely comminuted olecranon fractures, for which elbow stability becomes the main goal of surgery, remain a challenge for surgeons.
We conducted a study to determine the percentage loss of articular surface at which a bridge plating (BP) construct becomes too unstable and an acute shortening (AS) construct is required. The olecranon process of 8 fresh-frozen cadaveric upper limbs was serially resected. At each resection, the simulated fracture was fixed first with BP and then with AS. Stability was tested by performing valgus and varus stress tests at various angles under fluoroscopy.
As many as 6 serial resections were made on the cadaveric models. Maximum resection was 88%. The ulnohumeral joint remained stable to valgus and varus stress at all resections for both BP and AS. The elbow joint lost a significant amount of flexion with AS above 20% resection.
The ulnohumeral joint can tolerate substantial loss of articular surface in the olecranon before becoming unstable. In this study, range of motion was preserved more with the BP construct than with the AS construct. The presented data may be considered when approaching a severely comminuted olecranon fracture in which the articular surface cannot be reconstructed.
This study had several limitations. First, its fractures were simulated by serial resection of only the middle portion of the olecranon. In reality, comminution could extend farther proximally or distally and involve the surrounding tissues, which help stabilize the elbow. However, our focus was on loss of articular surface and stability, so keeping surrounding structures intact avoided confounding factors that could contribute to stability. A second possible limitation is that the implant used here may be different from the implant used in a clinical setting. However, our focus was not on fixation quality, and stability alone should not be affected by plate type. Third, stability was measured not quantitatively but instead subjectively under manual stress and fluoroscopy. We chose this method because it mimics what happens during surgery and is the clinical standard for stability assessment.24 Fourth, soft-tissue properties of the cadaver models used in this biomechanical study may differ from soft-tissue properties in vivo. This study could not evaluate possible long-term complications, such as posttraumatic arthritis and heterotopic ossification.5,10 There are no long-term studies comparing BP and other olecranon fixation methods in terms of postoperative elbow arthritis.
Conclusion
The ulnohumeral joint can tolerate substantial articular surface loss without compromising stability. As a result, in the management of highly comminuted olecranon fractures, BP may be considered before AS is performed. Quality and amount of intact proximal bone, rather than degree of comminution, may be more important factors in deciding which fixation method to use.
This biomechanical study is the first to focus on olecranon fracture BP without complete reconstruction of the articular surface. When treating a highly comminuted olecranon fracture that has an unreconstructible articular surface, surgeons may consider BP with or without bone graft, as well as AS. Our study findings suggest that, though both constructs maintain elbow stability, BP may have the advantage of maintaining ROM too. BP can avoid effects on triceps and elbow ROM, which may be more important in younger, more active patients. Clinical correlates are needed to validate these findings, as overall outcomes may be affected by concurrent fractures and injuries to surrounding structures.
