Background: The extensor carpi ulnaris (ECU) tendon has a distinct subsheath at the distal ulna. Symptomatic tears of this subsheath and subluxation of the ECU tendon often require reconstruction. We sought to determine the anatomical constraints of the ECU subsheath. Methods: The ECU subsheath was exposed on 12 fresh-frozen upper extremities. The tip of the ulnar styloid, the distal ulnar joint surface, and the proximal extent of the distal radio-ulnar joint were identified and dimensions measured. Subluxation of the tendon was then assessed with and without an intact subsheath in 9 specimens. The travel of the tendon was measured in pronation through supination and flexion before and after sectioning of the subsheath. Results: The ECU subsheath is 8.9 mm (standard deviation [SD] = 0.8 mm) wide proximally and 9.0 mm (SD = 1.2 mm) distally. The distal ulnar insertion is 0.5 mm (SD = 0.8 mm) proximal to the tip of the styloid, and stretches 10.2 mm (SD = 2.7 mm) proximally. From maximum pronation to maximum supination and flexion, the ECU tendon traveled 3.32 mm (SD = 4.24) medially when the subsheath was intact and 5.42 mm (SD = 5.0 mm) after sectioning. The maximum depth of the ulnar groove was 2.5 mm (1.59-3.56 mm). There was no significant association between changes in ECU subluxation and the depth of the ECU groove (Spearman’s rho = 0.25). Conclusion: The ECU subsheath is roughly 1 cm square stretching proximally from the ulnar styloid. ECU groove depth is not a significant independent predictor of tendon subluxation.
It is challenging to restore the clinically acceptable alignment of the distal radius after an acute on chronic fracture or after a secondary fracture occurring after malunion of a primary distal radius fracture. In cases of insignificant primary deformity, restoration to the primary deformity may suffice to obtain a successful clinical result. A borderline acceptable primary radial deformity can be unacceptable after the second injury, resulting in functional disability. If surgery is indicated, the surgeon must contend with both primary and secondary deformities to restore proper distal radius anatomy. We present our technique to correct both primary and secondary distal radius deformities through the new or secondary fracture plane.
AIM: Assess the scientific value and validity of the Fernandez classification to treat and study distal radius fractures. METHODS: A review article evaluated current and past literature to determine the interobserver reliability of the Fernandez classification and its application in distal radius fractures. A literature review was performed using search engines including Pubmed. RESULTS: The literature demonstrated kappa scores of initial distal radius fracture evaluation 0.39 and for a second look 3 months later to be 0.15. Intra-class correlations were 0.4 and 0.12 respectively demonstrating poor intra and interobserver reliability. Additionally, CT scans utilized after initial assessment via radiographs did not improve identification. CONCLUSION: This classification has only moderate reliability that was not improved by the addition of CT scans. When this classification was specifically tested in the clinical setting, it showed no reliability when predicting associated soft tissue or structure injury. The Fernandez classification system intention was to provide a treatment algorithm, it does not serve much use outside of its historical context in the understanding of distal radius fractures.
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