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Acute Shortening Versus Bridging Plate for Highly Comminuted Olecranon Fractures

The American Journal of Orthopedics. 2017 September;46(5):E330-E335
October 27, 2017 | The American Journal of Orthopedics
Meir Marmor, MD ; Keiko Amano, MD ; Akira Yamamoto, MD ; David Friedberg, MD ; Erik McDonald, BS ; Eric Meinberg, MD
Author and Disclosure Information

Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. 

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.

Each specimen was positioned with the arm draped in the lateral decubitus position, as in typical olecranon fracture surgery. A standard posterior approach to the olecranon was made with a midline posterior longitudinal skin incision. Subcutaneous flaps were developed, and the subcutaneous border of the proximal olecranon was exposed, preserving the medial and lateral collateral ligaments as well as the extensor mechanism. Baseline maximum flexion and extension of the elbow as well as olecranon length were measured with fluoroscopy (BV Pulsera, Philips) and ImageJ software (National Institutes of Health). 

To ensure reproducible anatomical reduction during plating, a 3.5-mm 4-hole nonlocking periarticular anatomically contoured plate (Zimmer Biomet) was applied posteriorly to the intact olecranon through a longitudinal slit in the distal triceps tendon. The plate was predrilled to house 4 nonlocking screws, 2 proximal and 2 distal.

Fracture Generation and Testing of Fixation Constructs

Figure 1.
Comminuted olecranon fractures were simulated by resecting a portion of the bone using an oscillating saw with a blade 2 mm thick. Resections were made perpendicular to the dorsal apex of the sigmoid notch under fluoroscopy guidance and were performed off the proximal and distal fragments interchangeably. At each resection, the specimen was repaired with the predrilled 3.5-mm BP and later with an AS construct (Figures 1A, 1B). For AS, the proximal fragment was advanced to the distal fragment and secured with a 3.5-mm screw, with the near cortex overdrilled to create a lagging effect. The resected surfaces of the olecranon were beveled without changing intra-articular length, and the proximal fragment was positioned to create a congruous surface for articulation with the trochlea. Both fixation methods, BP and AS, were used for each specimen at each resection. Serial resections were continued until the proximal fragment was too small for adequate fixation with 2 screws.
Figure 2.
After each fixation, radiographs were taken for measurement of maximum flexion and extension and amount of olecranon removed (Figures 2A, 2B). Gross stability to valgus and varus stress was examined under fluoroscopy after fixation, as it would be performed during surgery using manual valgus and varus load in full extension, 30° of flexion, and full extension in both supination and pronation. Any ulnohumeral joint line opening relative to baseline was considered a sign of instability.24
Figure 3.
On each radiograph, a marker was used to account for magnification artifacts. ROM was measured using the angle subtended by the longitudinal axis of the humeral shaft referenced by the anterior border of the humerus, and the longitudinal axis of the ulnar shaft referenced by the dorsal border of the ulna. The simulated fracture gap was measured at the articular surface. The articular surface length, measured before the resections, was used to calculate the percentage of the resected olecranon at each serial resection (Figure 3).

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