Insertional Torque in Cervical Vertebrae Lateral Mass Screw Fixation: Magerl Technique Versus Roy-Camille Technique.
METHODS
This is a prospective multicenter comparison study.


OBJECTIVE
To measure the insertional torque (IT) for cervical vertebra lateral mass screw (LMS) fixation using the Magerl and Roy-Camille methods, at the discretion of the surgeon.


BACKGROUND
Current fixation methods for patients with preoperative cervical spine instability use LMSs; however, few studies have closely examined intraoperative IT. Patients' bone quality was not measured.


METHODS
A total of 637 posterior cervical multiaxial screws were inserted for LMS (C3-C6) (Magerl technique, 423; Roy-Camille technique, 214) in 107 cases. Patients' mean age was 66 years. Patients treated with the Magerl method were divided into 2 groups, with the men in the MM group and the women in the MF group. Similarly, patients treated with the Roy-Camille method were divided into 2 groups, with the men in the RM group and the women in the RF group. The contralateral cortex was penetrated, and the IT at cerclage was measured at the last time.


RESULTS
IT of the lateral mass screw was 53.8±22.4, 45.4±21, 45.5±16.9, and 34±16.4 cN.m in the MM group (258), MF group (165), RM group (163), and RF group (51), respectively. The MM group had a significantly higher IT than the other 3 groups, and the RM group had a significantly higher IT than the RF group. When the correlation between screw length and IT was evaluated, IT was significantly (P<0.05) higher with a longer screw by the Magerl method.


CONCLUSIONS
The IT was higher with the Magerl method with a longer screw. Screw length and IT were not correlated with the Roy-Camille method; furthermore, the Roy-Camille method went through bilateral cortical bone perpendicularly, so that IT was determined by the fixation power in the cortical part of the bone, which was not thought to be affected by screw length.


METHODS
Level III.
*Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo †Department of Orthopaedics, Institute of Health Biosciences, University of Tokushima, Tokushima ‡Department of Orthopaedic Surgery, Takamatsu Red Cross Hospital, Kagawa §Department of Orthopaedic Surgery, Tokushima Municipal Hospital, Tokushima, Japan.
Akira
A
Shinohara
Koichi
K
Sairyo
Takuya
T
Mishiro
Takashi
T
Chikawa
Shigeru
S
Soshi
D000368:Aged; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods*; D019415:Torque