Isolated Partial Intra-Articular Volar Ulnar Fractures of the Distal Radius: The Tetrahedron Variant

Purpose The aim of this study was to assess the treatment and complications of a distinct type of partial intra-articular distal radius fracture. Methods Seven patients treated by the senior author between 2008 and 2013 for a partial intra-articular distal radius fracture with isolated involvement of the volar lunate facet were included. All fragments had the distinctive shape of a triangular-base pyramid (tetrahedron) extending from the metaphysis distally. All fractures were preoperatively assessed with computed tomography (CT) scans. Patients underwent surgical treatment using a standard flexor carpi radialis approach (2 patients) or a volar ulnar approach (5 patients) and were followed postoperatively for a minimum of 12 months. Results Patient age ranged from 33 to 66 years. On average, fragments measured 34 ± 6 mm in length (range, 27–43 mm) and were 48% as wide as the distal radius (range, 40% to 56%) and 58% as deep as the anterior-posterior dimension of the lesser sigmoid notch (range, 33% to 83%). Loss of reduction requiring revision surgery occurred at 4 weeks in 1 patient who underwent internal fixation through the flexor carpi radialis approach. The remaining cases healed uneventfully. At the final follow-up, all, except the patient requiring revision surgery, had a painless wrist. Average total wrist motion measured 87% of the opposite side. Radiographic healing with anatomic wrist alignment was observed in all except the patient requiring revision. This patient had persistent joint subluxation. The remaining patients all achieved good or excellent functional outcomes. Conclusions Isolated tetrahedron volar lunate facet fractures of the distal radius are rare. In our experience, the use of a volar ulnar approach leads to satisfactory fixation and outcomes, yielding excellent radiographic and clinical outcomes. Type of study/level of evidence Therapeutic V.