Instrumented ligamentotaxis and stabilization of compression and burst fractures of dorsolumbar and mid-lumbar spines

Abstract

Background: Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique employing the long straight rod or curved short rod without derotation to reduce fracture are practised together with short segment posterolateral fusion (PLF). Effects of the early postoperative mobilization without posterolateral fusion on reduction maintenance and fracture consolidation were not evaluated so far. The present prospective study is designed to assess the effectiveness of i) reduction and restoration of sagittal alignment, ii) no posterolateral fusion on the reduced, fractured vertebral body and injured disc, iii) fracture consolidation and iv) the fate of the unfused cephalad and caudal injured motion segments of the fractured vertebra.

Materials and methods: The study includes 15 Denis burst and two Denis type D compression fractures between T(12) and L(3). The lordotic distraction technique was used for ligamentotaxis utilizing the contoured short rods and pedicle screw fixator. Three vertebrae including the fractured one were fixed. The patients after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in vertebral body height, sagittal curve, reduction of retropulsion, improvement in neural deficit. The unfused motion segments, residual postoperative pain and bone and metal failure were also evaluated.

Results: The preoperative and postreduction percentile vertebral heights at, zero (immediate postoperative), at three, six and 12 months followup were 62.4, 94.8, 94.6, 94.5 and 94.5%, respectively. The percentages of the intracanal fragment retropulsion at preoperative, and postoperative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively. The preoperative and postreduction percentile loss of the canal dimension and at zero, three, six and 12 months were 52.1, 45.0, 44.0, 41.0 and 29% respectively suggesting that the under-reduced fragment was being resorbed gradually by a remodeling process. The mean initial kyphosis of 33° became mean 2° immediately after reduction and mean 3° at the final followup. The fractured vertebral bodies consolidated in an average period of ten weeks (range 8-14 weeks). The restored disc heights were relatively well maintained throughout the observation period. All paraparetic patients recovered neurologically. There were no postoperative complications.

Conclusion: Instrument-aided ligamentotaxis for compression and burst fractures utilizing the short contoured rod derotation technique and the instrumented stabilization of the fractured spine are found to be effective procedures which contribute to the fractured vertebral body consolidation without recollapse and maintain the motion segment function.

Keywords: Burst fracture; compression fracture; dorsolumbar and lumbar; fracture; short segment fixation; spine.

Figure 1

A technique of instrumented reduction of compression and burst fractures: Short vertebral fixation construct is used: three vertebral body fixations: one cephalad vertebra (ICV) + fractured vertebra (FV) + one caudate vertebra (ICV) construct. Arrows indicate the direction of distraction and the motion segment in which distraction force is applied. Posterior instrumentation with contoured rods, which provide consistent anatomic and lordotic distraction loads across the longitudinal axis and disc space, should best correct the vertebral height and intracanal fragment, while straight rods only provide axial distraction load. The uppermost column illustrates the lordotic distraction technique for compression fracture utilizing the contoured rods. This technique provides consistent anatomic and lordotic distraction loads across the longitudinal axis and uninjured ligament around the disc space should best correct the retropulsed vertebral height and intracanal fragment. Lower three columns illustrate the three reduction steps for instrumented ligamentotaxic reduction of superior (Denis type B) or inferior half body (Denis type C) burst fractures. The lowest column (Denis type burst A) illustrates the four steps of the reduction procedure, utilizing both upper and lower annular ligaments of the fractured vertebra

Figure 2.1

L₁ burst fracture with retropulsed fragment: (aA) Preoperative plain roentgenograms show collapsed shattered upper 1/2 of L₁ body with a retropulsed bony fragment and widened pedicle distance. (bB) Immediate postop roentgenograms show restored L₁ vertebral height and sagittal alignment. (cC) 14 months followup shows fracture consolidated and restored basis height

Figure 2.2

L₁ burst fracture with retropulsed fragment: (aA) Preoperative CT shows vertically collapsed upper 1/2 of L₁ body with a retropulsed fragment and (bB) well-reduced fracture is seen in postop CT. (cC) Fracture consolidated on 13 months followup

Figure 3.1

AP & Lateral x-ray showing L₃ burst fracture: Preoperative (A) and postoperative at 0 (B), 12 months (C), 13 months after implant removal (D)

Figure 3.2

L₃ burst fracture: Pre- (A) and postoperative (ten days, (B) eight (C) and 12 months (D)); serial CTs show the well-reduced fracture which has been well maintained until the last followup

Figure 3.3

L₃ burst fracture: MRI taken at postoperative 13 months, demonstrates the nondegenerated L_3-4 disc with pseudo-Schmorl's node in the upper end-plate of L₄

Figure 4

Line diagramme shows relationship of size of retropulsed fragment and/or other fracture fragments in front of the retropulsed fragment