Aims We aimed to evaluate the temperature around the nerve root during drilling of the lamina and to determine whether irrigation during drilling can reduce the chance of nerve root injury.
Materials and Methods Lumbar nerve roots were exposed to frictional heat by high-speed drilling of the lamina in a live rabbit model, with saline (room temperature (RT) or chilled saline) or without saline (control) irrigation. We measured temperatures surrounding the nerve root and made histological evaluations.
Results In the control group, the mean temperature around the nerve root was 52.0°C (38.0°C to 75.5°C) after 60 seconds of drilling, and nerve root injuries were found in one out of 13 (7.7%) immediately, three out of 14 (21.4%) at three days, and 11 out of 25 (44.0%) at seven days post-operatively. While the RT group showed a significantly lower temperature around the nerve root compared with the control group (mean 46.5°C; 34.5°C to 66.9°C, p < 0.001), RT saline failed to significantly reduce the incidence of nerve root injury (ten out of 26; 38.5%; odds ratio (OR) 0.96; 95% confidence interval (CI) 0.516 to 1.785; p = 0.563). However, chilled saline irrigation resulted in a significantly lower temperature than the control group (mean 39.0°C; 35.3°C to 52.3°C; p < 0.001) and a lower rate of nerve root injury (two out of 21; 9.5%, OR 0.13; 95% CI 0.02 to 0.703, p = 0.010).
Conclusion Frictional heat caused by a high-speed drill can cause histological nerve root injury. Chilled saline irrigation had a more prominent effect than RT in reducing the incidence of the thermal injury during extended drilling.
Cite this article: Bone Joint J 2017;99-B:554–60.
K. Tamai: Conception and design, Drafting the manuscript, Data acquisition, Analysis and interpretation of data.
A. Suzuki: Conception and design, Technical support, Critical revision of abstract.
S. Takahashi: Statistical analysis.
J. Akhgar: Data acquisition, Analysis and interpretation of data.
M. S. Rahmani: Data acquisition, Analysis and interpretation of data.
K. Hayashi: Data acquisition.
S. Ohyama: Data acquisition.
H. Nakamura: Critical revision of abstract, Supervision.
We thank the staff of the Central Laboratory of Morphology of Osaka City University for their excellent technical support.
This work was supported by Japan Orthopaedics and Traumatology Research Foundation Grant Number 334.
The author or one or more of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article.
This article was primary edited by G. Scott.
- Received August 22, 2016.
- Accepted December 14, 2016.
- ©2017 The British Editorial Society of Bone & Joint Surgery