Introduction

We report a single-centre, prospective, randomised study for pedicle screw insertion, by using a Computer Assisted Surgery (CAS) technique with three dimension (3D) intra-operative images intensifier versus conventional surgical procedure.

In recent years internal fixation of the spine by using posterior approach with minimally invasive and percutaneous technique were increasingly used in trauma. The percutaneous surgery lose information and navigation is supposed to provide better data because the lost information is found again. We hypothesise that a percutaneous minimal invasive dorsal procedure by using 3D intra-operative imaging for vertebral fractures allows short operating times with correct screw positioning and does not increase radiation exposure.

59 patients were included in this prospective, monocentric and randomised study. 29 patients (108 implants) were operated on by using conventional surgical procedure (CP) and 30 patients (72 implants) were operated on by using a 3D fluoroscopy-based navigation system (3D fluo). In the two groups, a percutaneous approach was performed for transpedicular vertebroplasty or percutaneous pedicle screws insertion. In the two groups surgery was done from T4 level to L5 levels. Patients (54 years old on average) suffered trauma fractures, fragility fractures or degenerative instabilities. Evaluation of screw placement was done by using post-operative CT with two independent radiologists that used Youkilis criteria. Operative and radiation running time were also evaluated.

With percutaneous surgery, the 3D fluo technique was less accurate with 13.88% of misplaced pedicle screws (10/72) compared with 11.11% (12/108) observed with CP. The radiation running time for each vertebra level (two screws) reached on average 0.56 mSv with 3D fluo group compared to 1.57 mSv with the CP group. The time required for instrumentation (one vertebra, two screws) with 3D fluo was 19.75 minutes compared with CP group 9.19 minutes. The results were statistically significant in terms of radiation dose and operative running time (p < 0.05), but not in terms of accuracy (p= 0.24).

With percutaneous procedures, 3D fluoroscopy-based navigation (3D fluo) system has no superiority in terms of operative running time and to a lesser degree in terms of accuracy, as compared to 2D conventional procedure (CP), but the benefit in terms of radiation dose is important. Other advantages of the 3D fluo system are twofold: up-to-date image data of patient anatomy and immediate availability to assess the anatomical position of the implanted screws.

Purpose of the study: Defective reduction and secondary displacement after osteosynthesis of distal radius fractures can compromise wrist function. Volar locking plates enable solid fixation which remains stable over time but section of the pronator quadrates necessary for the anterior approach raises the risks of destabilising the distal radioulnar joint and loss of pronation force. Our study was designed to evaluate recovery of grip, pronation and supination force after volar locking plate fixation.

Material and methods: This was a prospective study of 29 fractures of the distal radius with dorsal displacement fixed with a volar locking plate in 28 patients (17 men, 11 women, mean age 48.75 years) from January 2007 to May 2008. The quality of the pronator quadrates suture was assessed at the end of the operation. The assessment included the classical parameters of wrist movement, the Herzberg and Dumontier score, radial slope and ulnar variance on the ap and lateral views of the wrist, and recovery of grip, pronation and supination force compared with the opposite side using an ambulatory device.

Results: The pronator quadratus suture was considered solid in eight cases, precarious in seven. Complete suture was not possible in 14 cases. At mean follow-up of 10 months, patients had on average recovered 77% of the grip force, 74% of the pronation force, and 76% of supination force, compared with the opposite side. Complications included one defective reduction, one secondary displacement (by defective plate position), two dystrophy syndromes, and four posttrauma carpal tunnel syndromes.

Discussion: The literature shows that volar plate fixation enables recovery of 74% to 84% of grip force. Few studies have examined the recovery of pronosupination and none have described results after osteosynthesis for fracture. Our study did not find that section of the pronator quadrates, a muscle difficult to suture, had a deleterious effect.

Conclusion: Osteosynthesis using a volar locking plate for distal fractures of the radius remains a controversial issue. Study of recovery of the grip, pronation and supination force did not reveal any prejudice attributable to this technique.