IntroductionIn combined posterior–anterior stabilization of thoracolumbar burst fractures, the expandable vertebral body replacement device (VBRD) is typically placed bisegmentally for anterior column reconstruction (ACR). The aim of this study, however, was to assess feasibility, outcome and potential pitfalls of monosegmental ACR using a VBRD. In addition, clinical and radiological outcome of monosegmental ACR was related to that of bisegmental ACR using the same thoracoscopic technique.MethodsThirty-seven consecutive neurologically intact patients with burst fractures of the thoracolumbar junction (T11–L2) treated by combined posterior–anterior stabilization were included. Monosegmental ACR was performed in 18 and bisegmental ACR in 19 patients. Fracture type and extent of vertebral body comminution were determined on preoperative CT scans. Monosegmental and bisegmental kyphosis angles were analyzed preoperatively, postoperatively and at final radiological follow-up. Clinical outcome was assessed after a minimum of 2 years (74 ± 45 months; range 24–154; follow-up rate 89.2%) using VAS Spine Score, RMDQ, ODI and WHOQOL-BREF.ResultsMonosegmental ACR resulted in a mean monosegmental and bisegmental surgical correction of − 15.6 ± 7.7° and − 14.7 ± 8.1°, respectively. Postoperative monosegmental and bisegmental loss of correction averaged 2.7 ± 2.7° and 5.2 ± 3.7°, respectively. Two surgical pitfalls of monosegmental ACR were identified: VBRD positioning (1) onto the weak cancellous bone (too far cranially to the inferior endplate of the fractured vertebra) and (2) onto a significantly compromised inferior endplate with at least two (even subtle) fracture lines. Ignoring these pitfalls resulted in VBRD subsidence in five cases. When relating the clinical and radiological outcome of monosegmental ACR to that of bisegmental ACR, no significant differences were found, except for frequency of VBRD subsidence (5 vs. 0, P = 0.02) and bisegmental loss of correction (5.2 ± 3.7° vs. 2.6 ± 2.5°, P = 0.022). After exclusion of cases with VBRD subsidence, the latter did not reach significance anymore (4.9 ± 4.0° vs. 2.6 ± 2.5°, P = 0.084).ConclusionsThis study indicates that monosegmental ACR using a VBRD is feasible in thoracolumbar burst fractures if the inferior endplate is intact (incomplete burst fractures) or features only a single simple split fracture line (burst-split fractures). If the two identified pitfalls are avoided, monosegmental ACR may be a viable alternative to bisegmental ACR in selected thoracolumbar burst fractures to spare a motion segment and to reduce the distance for bony fusion.

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Introduction: Internal fixation for undisplaced scaphoid fractures is becoming increasingly popular, especially in a young and active population. Although in a clinical setting it can be difficult, central placement is important for successful percutaneous screw fixation. It decreases time to fracture union and is biomechanically stronger. In this study we investigated the different possibilities to obtain a more central screw placement through a volar approach. Methods: We performed measurements on 20 CT scans of unfractured scaphoids. In the first part of the study, a central virtual guidewire was drawn in the sagittal and coronal plane in ten scaphoids to delineate the optimal placement of a screw for scaphoid fixation. The same procedure was repeated with the wrist in extension and ulnar deviation to look for dynamic variations. Secondly, in ten scaphoids a comparison was made between the central virtual guidewire, one that represents a transtrapezial approach and one for a standard volar approach. Results: The central virtual guidewire always transected the trapezium with either a neutral position of the wrist or extension and ulnar deviation. The average clearances in the frontal plane were 2.347 and 2.416 mm (P ¼ 0.7216), in the sagittal plane 4.697 and 4.029 mm (Po0.0001), respectively. Comparing a centrally placed guidewire to the transtrapezial approach, no statistical difference could be found. The transtrapezial approach was statistically better (Po0.001) for central screw placement than the standard volar approach in the distal and midwaist plane. Discussion: The ideal position for a screw in scaphoid fixation is centrally. This CT study shows that central placement of a screw in the scaphoid, using a volar approach, can be done by placing the guidewire through the trapezium. Alternatively, part of the trapezium needs to be resected or the scaphotrapezial joint needs to be opened and manipulated to allow exact central placement in the scaphoid.

that lateral trauma can give dislocation because fracture of the metacarpal bone is impossible and the axial trauma of the thumb could destroy the osteointegration of the cup. This prosthesis seems a good possibility for treating the painful osteoarthritis of CMC joint of the thumb.Ligamentous capsulodesis or bone-ligament-bone grafts are established methods to reconstruct the scapholunate interosseous ligament in chronic scapholunate dissociation. The purpose of our anatomical study was to create a new bone-ligament-bone-graft, which can be used as an anatomical replacement for the scapholunate interosseous ligament.The plantar aponeurosis of the metatarso-phalangealjoint of the second to fifth toe as well as of the proximalinterphalangeal joint of the second to fourth toe were examined. The length as well as the thickness of the ligamentous structures of the joints of 20 human cadaveric specimens (40 feet) were measured. The length -the most important category -of the metatarsophalangeal-joints proved to be significantly larger than the original SL-ligament in all cases. In contrast, the SLligament showed a similar length compared to the plantar aponeurosis of the proximal-interphalangealjoint of the forth and third toe. The average length of the plantar aponeurosis (D4) was 0.62 cm (range 0.4-0.8 cm), the average length of D3 0.63 cm (range 0.4-0.8 cm). The average thickness of the plantar aponeurosis of the proximal-interphalangeal-joint D3 and D4 was 0.7 mm (range 0.3-1.4 mm). The width of the plantar aponeurosis of the PIP-joint was 0.82 cm (range 0.70-0.93 cm) on average at D3 and 0.78 cm (range 0.60-1.00 cm) at D4. A small wedge-shaped piece of bone attaching the ligament proximal and distal could be separated using a bone saw. Finally, a boneligament-bone-graft of the aponeurosis of the metatarso-phalangeal-joint as a SL-ligament substitute was designed and could be transplanted in cadaveric hands. The new bone-ligament-bone graft is located between the scaphoid and lunate like the original SL-ligament. Additional biomechanical studies investigating the strength of the newly designed graft have to be done in the near future.