Lunate Fragment Research Articles

873 The Keystone Challenge- Volar Displaced Intra-Articular Distal Radius Fractures with Lunate Fossa Fragment

Abstract Aim Volar displaced fractures of the distal radius are unstable and warrant operative management. A subset of patients with volar displaced fractures also has a separate lunate fossa fragment, a specific injury with greater instability that may precipitate carpal subluxation. We aim to review our long-term experience in the management of this complex injury, exploring surgical technique which may improve treatment. Method We retrospectively reviewed all volar displaced distal radius fixations between 2015 and 2020. Inclusion criteria: any displaced intra-articular volar distal radius fracture with lunate fragment involvement undergoing volar fixation and over 16 years of age. Exclusion criteria: shaft fractures, extra-articular fractures, open fractures, fractures fixed using k-wires or external fixation, revision surgery and patients without follow-up. We adapted our surgical approach in order to address this more complex fracture pattern, and all operations were performed by specialist hand surgeons. Results 468 distal radius fractures were assessed, of which 29 (6%) cases included a lunate fossa fragment. 20 (69%) of patients were female, mean age was 59 years (SD 12.4). Mean length of stay was 5 hours and mean operative time was 96 mins (range 79-95). No patients had carpal subluxation, fracture fixation failure or return to theatre for any reason. Conclusions From our experience as a specialist orthopaedic institution, we recommend the extended FCR approach and intra-focal exposure to manage this complex injury. In particular, the lunate fossa fragment is the keystone which requires dedicated reduction prior to tackling the remaining fracture configuration.

Comparison of the Orientation Angles of Volar Locking Plate Distal Ulnar Locking Screw for Distal Radius Fractures

This study aimed to measure the angles between the screw and plate in 16 commercially available volar locking plates (VLPs) to determine the fixable intra-articular fragment size. Ulnar orientation angles (axial plane) and elevation angles (sagittal plane) between the distal ulnar screw and plate were measured for 14 fixed-angle VLPs and 2 variable-angle VLPs. Each VLP was simulated by 2 surgeons to sit distally and ulnarly in 10 normal distal radius models. The distance between the screw and distal/ulnar end of the distal radius on both the volar and dorsal sides, designated as the longitudinal/lateral distance, was measured to identify the fixable size of the 2 intra-articular fragments: volar lunate fragment and dorsoulnar fragment. Relationships between the ulnar orientation angle and dorsal-side lateral length as well as the elevation angle and dorsal-side longitudinal distance were analyzed. The ulnar orientation and elevation angles ranged from 6.5° to 16.9° and-5.8° to 34.3°, respectively, for fixed-angle VLPs and-12.5° to 32.2° and 3.1° to 42.1°, respectively, for variable-angle VLPs. The minimal longitudinal distances on the volar side with the fixed- and variable-angle VLPs were 4.3-10.9 mm and 5.8-5.9 mm, respectively. On the dorsal side, the lateral distance negatively correlated with the ulnar orientation angle (R=-0.74), and the longitudinal distance negatively correlated with the elevation angle (R=-0.89). The Depuy Synthes variable-angle VLP provides an advantage for fixating small intra-articular fragments. For fixed-angle VLPs, the Mizuho VLP provides an advantage for fixating small volar lunate fragments. A narrow dorsoulnar fragment can be fixated using a plate with a large ulnar orientation angle, such as the Zimmer Biomet or Mizuho VLP. The ability of each individual commercially available plate to capture specific intra-articular fragments should be known.

Lunate Fragments in Unstable Scaphoid Nonunion Wrists: Affect or Effect?

Lunate Fragments in Unstable Scaphoid Nonunion Wrists: Affect or Effect?

Melone's Concept Revisited: 3D Quantification of Fragment Displacement.

We applied quantitative 3D computed tomography to 50 complete articular AO type C fractures of the distal radius and tested the null hypothesis that fracture fragments can be divided according to Melone's concept (radial styloid and volar and dorsal lunate facet fragments) and that each fragment has similar (1) displacement and (2) articular surface area. Thirty-eight fractures fit the Melone distribution of fragments. Radial styloid fragments were most displaced, and volar lunate fragments were least displaced. Volar lunate fragments had the largest articular surface area. While these findings confirm Melone's concepts, the finding that volar lunate fragments are relatively large and dorsal lunate fragments relatively small suggests that alignment of the volar lunate fragment with the radial styloid may be the key element of treatment and the dorsal lunate fragment may not routinely benefit from specific reduction and fixation.

Neglected Isolated Lunate Fracture

Received: November 1, 2013 Revised: March 11, 2014 Accepted: March 24, 2014 Correspondence to: Hyun-Soo Park Department of Orthopaedic Surgery, KEPCO Medical Center, 308 Uicheon-ro, Dobong-gu, Seoul 132-703, Korea TEL: +82-2-901-3078 FAX: +82-2-900-1745 E-mail: deanzang2@hanmail.net Isolate fracture of lunate is very rare. The authors reported a neglected fracture of lunate which was founded incidentally after the dorsal wall fracture of triquetrum. Pain reduction and improvement of range of motion was achieved after excising the dorsal fragment of lunate.

Volar Plating of AO C3 Distal Radius Fractures: Biomechanical Evaluation of Locking Screw and Locking Smooth Peg Configurations

The goal of this study was to determine whether locking screws or smooth locking pegs optimize fixation of AO C3 intra-articular distal radius fractures. A secondary goal was to determine which combinations of locking screws and smooth locking pegs influence construct stability. In anatomic radius models, AO C3 intra-articular distal radius fractures were fixed using volar locking plates. For the first part, 16 specimens were randomized to receive either 2 locking screws or 2 smooth locking pegs in each of the 3 pairs of holes in the plate. For the second part, 30 specimens were randomized to receive any 4 combinations of locking screws and smooth locking pegs in each of the 3 pairs of holes. Axial loading to failure was applied. Constructs consisting of 4 smooth locking pegs within the lunate fragment were significantly weaker than constructs with 4 locking screws (means 626 N vs 981 N, respectively). Constructs with smooth locking pegs in the ulnar positions of the lunate fragment were weaker than with locking screws in these positions (means 737 N vs 977 N, respectively). Locking screws in the subchondral position of the lunate fragment were stronger than smooth locking pegs in these positions (means 1,227 N vs 934 N, respectively) and any other combination (means 1,227 N vs 942 N, respectively). Use of locking screws as opposed to smooth locking pegs for AO C3 intra-articular distal radius fractures, particularly subchondral and in the ulnar side of the lunate fragment, optimizes construct stability. This may have implications on postoperative rehabilitation protocols and may limit costs related to use of volar locking plates.

An approach to Kienböck's disease: Triscaphe arthrodesis

Sixteen patients with Kienböck's disease were treated with triscaphe arthrodesis (fusion of the scaphoid, trapezium, and trapezoid) with or without silicone rubber lunate arthroplasty. This approach removes compressive stress from the diseased lunate and treats the accompanying rotary subluxation of the scaphoid. Five patients were treated with triscaphe arthrodesis together with silicone rubber lunate arthroplasty. Three patients, who were symptomatic, after receiving silicone rubber lunate arthroplasty elsewhere, were treated with triscaphe arthrodesis. Eight patients were treated with triscaphe arthrodesis alone, without silicone rubber lunate arthroplasty. Two of these eight patients later required silicone rubber lunate arthroplasty. Radial styloidectomy and small lunate fragment excision were performed later on one patient. After an average follow-up of 20.5 months, relief of pain was satisfactory in all 16 patients. There was neither nonunion nor surgical infection. We believe that triscaphe arthrodesis with a silicone rubber lunate provides a means for load transference and heavy stress use capability of the hand. Triscaphe arthrodesis alone may suffice to bear the wrist load and can be used in an effort to preserve the diseased lunate. A silicone rubber lunate can easily be added at a later date if necessary.