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Orthopaedic Surgery Spine
Pedicle Lesional Screws and Calcium Phosphate Cement in
Acute Thoracolumbar Burst Fractures
a report by
H Vouaillat, J Tonetti, A Bodin, A Eid, C Vasile and P Merloz
Orthopaedic and Trauma Department, Michallon University Hospital
In the last few decades, a reduction procedure has been used to preserve At admission, the angulation of vertebral kyphosis (VK) was 18° (range:
as much lumbar mobility as possible after compression-type 7–30; SD 5). Angulation was measured on the lateral view between the
thoracolumbar fractures.
1,2
Four pedicle screws – two above and two lower plateau and the projection of the upper plateau of the broken
below the crushed vertebra – provide support for the damaged vertebral vertebra, and regional angulation was measured between the upper
body.
3
Forces from the adjacent vertebrae are transferred to the plateau of the vertebra above and the lower plateau of the vertebra
remaining intact ligaments by traction: the ventral longitudinal ligament, below the broken vertebra. Corrected regional angulation (CRA) was
the annulus attachment at the rim of the vertebral plateau and the dorsal obtained by subtracting the normal lordotic angulation of the area from
longitudinal ligament pull the peripheral bony fragments up and down, the regional angulation.
8
The mean CRA was 11° (range: 3–24; SD 2).
performing ligamentotaxis.
4
After the reduction procedure, the height,
width and anteroposterior (AP) length of the vertebral body are restored The compression sustained by the vertebral body was also analysed. The
in the radiological AP and lateral views. The screw-rod connection – height of the crushed body was compared with that of the adjacent
which nowadays is very powerful – maintains the reduction, and laminar levels. Vertebral body compression was calculated using anterior height
hooks can be added at the ends to reinforce the placement of the device (AH), medial height (MH) and posterior height (PH) at the broken vertebra
and avoid screw pull-out. However, systematic post-operative computed (0), at the vertebra above (1) and at the vertebra below (2) (see Figure
tomography (CT) scans often reveal whether there is a lack of reduction 1A). The percentage of anterior vertebral body compression (AC) was
of the central plateau, which remains in the spongeous bone, or, when obtained using the following formula:
plateau reduction is achieved, an empty space underneath the plateau
after impaction of the spongeous bone. This space may be responsible for AC = 1 – A0 ÷ [(A1 + A2]) ÷ 2]
secondary loss of reduction in kyphosis. Daniaux proposed filling that
space using bone grafts.
5
Recently, the authors used calcium phosphate Percentages of medial vertebral body compression (MC) and posterior
cement in an attempt to achieve this goal in kyphoplasty procedures.
6
vertebral body compression (PC) were calculated using the same formula.
To complement the ligamentotaxis performed by the reduction device, we Patients underwent surgery using the posterior approach. Buttresses
proposed first to relieve the impaction of the central plateau by were placed at the anterosuperior iliac spine and sternum to keep the
performing intracorporeal procedures to push up the central plateau, spine in lumbar lordosis and the stomach free from compression.
followed by the insertion of lesional screws into the pedicles of the broken Fourteen laminectomies were performed on fractures with narrowing of
vertebra. Before implantation of the lesional screws, the space underneath the vertebral canal. Large pedicle screws were inserted in the adjacent
the plateau is filled with calcium phosphate cement. The pedicle lesional vertebrae (5.5–6.5mm monoaxial Legacy™ screws, Medtronic Inc.,
screws are secured by the crystallisation of the cement, precluding the Memphis, TN, US). Customised forceps were securely attached to the
need for laminar hooks. The aim of this article is to report the clinical and screws and applied force to the vertebrae above and below the broken
radiological results of this technique from a short pilot study. vertebra to perform ligamentotaxis. The pedicles of the broken vertebra
were then prepared and curettes were inserted obliquely and convergent
Materials and Methods to the vertebral body. A lever-like manoeuvre was then used to push the
The authors operated on 40 patients at Michallon University Hospital central plateau up. Once reduction of the central plateau was achieved,
between July 2003 and November 2006. Thirteen of the patients were a space was created in the spongeous bone. Approximately 3–6ml of
female and 27 were male. The mean age was 37 years (range: 19–70; calcium phosphate radio-opaque cement (Calcibon™, BIOMET, Valence,
standard deviation (SD) 13). Each patient had presented with the destruction France) was injected into this space at a low pressure through a flexed,
of a single vertebral body (see Figure 1). The distribution of fracture types large, short canula using a 60ml syringe. All intracorporeal procedures
according to the Magerl et al. classification system was: six A2 fractures; 29 and injection steps were performed under lateral view fluoroscopic
A3 fractures;
7
and five B1 fractures, which we included in the study because control (see Figure 2). In case of leakage into the medullar canal, the
the injuries incorporated a compression of the vertebral body. A surgeon was prepared to perform a laminectomy. Finally, lesional screws
pre-operative CT scan was performed for each patient to provide a full were implanted into the pedicles of the broken vertebra. A lordotically
description of the fracture and to rule out any type C or type A1 fractures. shaped 5.5mm bar was placed on each side and used to tighten the
Fractures occurred at T12 (five cases), L1 (25 cases), L2 (seven cases) or L3 screw heads in order to fix the reduction before the cement crystallised.
(three cases). No medullar or radicular damage was encountered in patients The patient was authorised to walk the day after surgery, and a seated
with Frankel E-type fractures. Twenty of the fractures were caused by sport- position was permitted on the third post-operative day. No brace or
related accidents. Serious associated injuries were present in nine cases. corset was required.
80 © TOUCH BRIEFINGS 2007
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