Understanding the Radiographic Anatomy of the Proximal Ulna and Avoiding Inadvertent Intraarticular Screw Placement.

OBJECTIVES: To map the proximal ulnar articular margins and ensure safe extraarticular placement of implants. METHODS: Ten fresh frozen adult elbow cadaver specimens were obtained. Radiopaque wire was applied to the articular margin of the articular facets and the central trochlear ridge of the proximal ulna. Fluoroscopic images were obtained demonstrating the articular facet margins. Radiographic measurements were performed and used to identify relative safe screw zones. RESULTS: All specimens demonstrated marked extension of the ulnar and radial facets dorsal to the central trochlear ridge. The dorsal extent of the ulnar facets from the central trochlear ridge averaged 9.7 mm (range, 7.9-13 mm; SD, 1.5 mm) and 6.2 mm (range, 3.4-9.4 mm; SD, 1.9 mm), respectively. The average footprint of the posterior ulnar facet occupied 44% (±4.9%) of the total ulnar height from the dorsal cortex to the trochlear ridge. CONCLUSIONS: The articular margins of the anterior and posterior facets of the proximal ulna are challenging to identify radiographically. A surgical "at-risk zone" exists within 9.7 mm from the radiographic margin of the central trochlear ridge. Implants placed within this zone have the potential to violate the articular surface.

Intramedullary Cage Fixation for Proximal Humerus Fractures Has Low Reoperation Rates at 1 Year: Results of a Multicenter Study.

OBJECTIVES: To determine reoperation rates after treatment of a proximal humerus fracture with cage fixation. DESIGN: Retrospective case series. SETTING: Eleven U.S. hospitals. PATIENTS: Fifty-two patients undergoing surgical treatment of proximal humerus fractures. INTERVENTION: Open reduction and internal fixation of a proximal humerus fracture with a proximal humerus cage. MAIN OUTCOME MEASUREMENTS: Reoperation rate at 1 year. RESULTS: At a minimum follow-up of 1 year, reoperations occurred in 4/52 patients (7.7%). Avascular necrosis (2/41) occurred in 4.9% of patients. CONCLUSION: Standard locked plating remains an imperfect solution for proximal humerus fractures. Proximal humerus cage fixation had low rates of revision surgery at 1 year. Proximal humerus cage fixation may offer reduced rates of complication and reoperation when compared with conventional locked plating for the management of proximal humerus fractures. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.