Lag screws in vertebral-pincer-fractures

M. Auerswald, P. Messer, K. Sellenschloh, M.M. Morlock, J. Wahlefeld, D. Rundt, M. Faschingbauer, G. Huber


Vertebral pincer-fractures are rare injuries and still there is no consensus concerning their stability. According to Magerl et al.1 they are to be treated conservatively. However, due to a high nonunion rate they are frequently stabilized. In previous therapeutical concepts vertebral-pincer-fractures were treated either by indirect stabilization or resection2

Although the lag-screw principle is established in fractures of the skeleton, it has in spite of its low invasiveness no significance in spinal surgery so far. 

The aim of this study is to evaluate the lag screw principle in vertebral fractures biomechanically and to verify segment stiffness similar to nonfractured  specimen.

18 human spines are analysed. Each of the bisegmental human specimens are tested using a follower-load3, in extension/flexion, torsion and lateral bending. 

In comparison to the native specimen, it is expected that the non-stabilized specimen exhibit increasing values for extending movement, while the stabilized specimen, after osteosynthesis, show decreasing values. 

Till now lag screws are not used in spinal traumatology as reconstructive treatment, but it seems possible to get bony healing by using it in sufficiently big vertebral fragments. All material can be removed after radiological guaranteed healing. Possibly, the treatment can be the first reconstructive procedure in the treatment of vertebral pincer fractures. 


  1. Magerl, F., Aebi, M., Gertzbein, S. D., Harms, J. & Nazarian, S. A comprehensive classification of thoracic and lumbar injuries. Eur. Spine J. 3, 184–201 (1994).
  2. Ladurner, A., Forster, T. & Külling, F. A. Wirbelkörperfrakturen im Rahmen eines generalisierten epileptischen Anfalls. Unfallchirurg 118, 1067–1069 (2015).
  3. Patwardhan, A. G., Havey, R. M., Meade, K. P., Lee, B. & Dunlap, B. A follower load increases the load-carrying capacity of the lumbar spine in compression. Spine (Phila. Pa. 1976). 24, 1003–9 (1999).