Pedicle screw fixation methods for traumatic fractures of the thoracic and lumbar spine

Thoracic and lumbar spine fractures are the most common injuries of the spine. An exaggerated curvature (kyphosis) at the end of treatment may predispose to later back pain and a poor functional outcome. If the nerve root or spinal cord is damaged, partial or complete loss of sensory and motor function in the legs, and urinary and faecal incontinence may result. Treatment depends on the individual characteristics of the fracture, with options including bed rest alone, closed reduction of the fracture and functional bracing, and surgery involving open reduction and internal fixation of the fracture. Surgery frequently involves posterior pedicle screw fixation, where typically screws are placed in the 'pedicle' parts of the vertebrae (bones of the spine) adjacent to the damaged vertebrae and connected by rods to hold the bones in place and stabilise the fracture while it heals. This review examined the evidence for the different types of pedicle screw fixation and for additional support such as fusion, where bone graft (usually taken from bone near the hip region of the patient) or substitute is added to the spine. The latter aims to reduce movement of the injured segment and any associated pain.

The review authors found eight trials that included a total of 448 patients with thoracic and lumbar spine fractures. These trials were small and were at risk of bias that could have affected their findings. Five comparisons of different methods of pedicle screw fixation were tested by the included trials. For each comparison, no differences were found in function, activities of daily living, or pain in the two treatment groups. Aside from one person, who required further surgery to treat a temporary decline in neurological status, no report described any trial participant who showed a permanent decline in neurological status. Notably, two of the three trials testing fusion reported that a quarter to two thirds of participants had long-term pain at the donor site where the bone graft had been taken.

The review authors concluded that evidence is insufficient to inform on the selection of different methods of pedicle screw fixation or on the use of fusion with pedicle screw fixation.

Authors' conclusions: 

This review included only eight small trials and five different comparisons of methods of pedicle fixation in various participants while looking at a variety of outcomes at different time points. Overall, evidence is insufficient to inform the selection of different methods of pedicle screw fixation or the combined use of fusion. However, in the absence of robust evidence to support fusion, it is important to factor the risk of long-term donor site pain related to bone harvesting into the decision of whether to use this intervention. Further research involving high-quality randomised trials is needed.

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Background: 

Spine fractures are common. The treatment of traumatic fractures of the thoracic and lumbar spine remains controversial but surgery involving pedicle screw fixation has become a popular option.

Objectives: 

To assess the effects (benefits and harms) of pedicle screw fixation for traumatic fractures of the thoracic and lumbar spine.

Search strategy: 

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library, 2011 Issue 1), MEDLINE (1948 to March 2011), EMBASE (1980 to 2011 Week 11), the Chinese Biomedical Database (CBM Database) (1978 to March 2011), the WHO International Clinical Trials Registry Platform (March 2011), reference lists of articles and conference proceedings.

Selection criteria: 

Randomised controlled trials (RCTs) and quasi-randomised controlled trials comparing pedicle screw fixation and other methods of surgical treatment, or different methods of pedicle screw fixation, for treating traumatic fractures of the thoracic and lumbar spine.

Data collection and analysis: 

Three review authors independently performed study selection, risk of bias assessment and data extraction. Limited meta-analysis was performed.

Main results: 

Pedicle screw fixation versus other methods of surgery that do not involve pedicle screw fixation was not looked at in any of the identified trials. Studies that were identified investigated different methods of pedicle fixation.

Five randomised and three quasi-randomised controlled trials were included. All were at high or unclear risk of various biases, including selection, performance and detection bias. A total of 448 patients with thoracic and lumbar spine fractures were included in the review. Participants were restricted to individuals without neurological impairment in five trials. The mean ages of study populations of the eight trials ranged from 33 to 41 years, and participants had generally experienced traumatic injury. Mean follow-up for trial participants in the eight trials ranged from 28 to 72 months.

Five comparisons were tested.

Two trials compared short-segment instrumentation versus long-segment instrumentation. These studies found no significant differences between the two groups in self-reported function and quality of life at final follow-up. Aside from one participant, who sustained partial neurological deterioration that was resolved by further surgery (group not known), no neurological deterioration was noted in these trials.

One trial comparing short-segment instrumentation with transpedicular bone grafting versus short-segment fixation alone found no significant difference between the two groups related to patient-perceived function and pain at final follow-up. All participants had normal findings on neurological examination at final follow-up.

Two trials compared posterior instrumentation with fracture level screw incorporation ('including' group) versus posterior instrumentation alone ('bridging' group). Investigators reported no differences between the two groups in patient-reported function, quality of life, or pain at final follow-up. One trial confirmed that all participants had normal findings on neurological examination at final follow-up.

One trial comparing monosegmental pedicle screw instrumentation versus short-segment pedicle instrumentation found no significant differences between the two groups in Oswestry Disability Index results or in pain scores at final follow-up. No neurological deterioration was reported.

Three trials compared posterior instrumentation with fusion versus posterior instrumentation without fusion. Researchers found no differences between the two groups in function and quality of life or pain. No participants showed a decline in neurological status in any of the three trials, and no significant difference was reported between groups in the numbers whose status had improved at final follow-up. Two trials stated that patients in the fusion group frequently had donor site pain. Other reported complications included deep vein thrombosis and superficial infection.

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