Role of moss miami pedicle screw system in unstable spinal injuries

ABSTRACT

To find out the role of instrumentation with MOSS Miami [by DePuy, Johnson and Johnson] implants to treat patients with unstable thoraco-lumbar spinal fractures and dislocations in terms of stability achieved and improvement in neurological status. Quasi-experimental study. This study was conducted in orthopaedic department of Combined Military Hospital Rawalpindi from Oct 2001 to Oct 2004. 80 patients with unstable spinal injuries were operated during above time period. 48 patients underwent posterior transpedicular MOSS Miami instrumentation of thoraco-lumbar spine. Instability was defined according to White and Panjabi's criteria. Neurological deficit was defined according to American Spinal Injuries Association [ASIA] Impairment Scale [AIS]. Those with complete injury were placed in group I [29 cases] and rest were assigned group II [19 cases]. All cases were treated by open reduction and short segment internal fixation using MOSS Miami pedicle screw system. Patients were followed up 2 weeks, 6 weeks, 3 months, 6 months and yearly after operation. Patients were observed for correction of deformity, spinal fusion, improvement in neurological status, loss of reduction over time, back pain and rehabilitation. All data was put in a dedicated MS Access Data Base and analysed using SPSS. It was observed that those with complete neurological deficit only 5 cases improved out of 29 cases and the mean AIS improvement was 0.39 / case. Out of those with partial neurological deficit, all cases showed improvement. There was no deterioration in neurological status. Mean AIS improvement was 1.4 / case. Solid spinal union was observed in 45 cases out of 48 cases at the end of 3 months. 03 cases had implant related complications. The vertebral deformity was completely restored in 32 cases and incompletely in 16 cases. Loss of reduction was 2.5 [degree sign] on average. MOSS Miami pedicle screw system is safe and effective for posterior short segment fixation of unstable thoraco-lumbar fractures