Anterior lumbar interbody fusion with stand-alone interbody cage in treatment of lumbar intervertebral foraminal stenosis : comparative study of two different types of cages

Abstract

Objective: This retrospective study was performed to evaluate the clinical and radiological results of anterior lumbar interbody fusion (ALIF) using two different stand-alone cages in the treatment of lumbar intervertebral foraminal stenosis (IFS).

Methods: A total of 28 patients who underwent ALIF at L5-S1 using stand-alone cage were studied [Stabilis(R) (Stryker, Kalamazoo, MI, USA); 13, SynFix-LR(R) (Synthes Bettlach, Switzerland); 15]. Mean follow-up period was 27.3 +/- 4.9 months. Visual analogue pain scale (VAS) and Oswestry disability index (ODI) were assessed. Radiologically, the change of disc height, intervertebral foraminal (IVF) height and width at the operated segment were measured, and fusion status was defined.

Results: Final mean VAS (back and leg) and ODI scores were significantly decreased from preoperative values (5.6 +/- 2.3 --> 2.3 +/- 2.2, 6.3 +/- 3.2 --> 1.6 +/- 1.6, and 53.7 +/- 18.6 --> 28.3 +/- 13.1, respectively), which were not different between the two devices groups. In Stabilis(R) group, postoperative immediately increased disc and IVF heights (10.09 +/- 4.15 mm --> 14.99 +/- 1.73 mm, 13.00 +/- 2.44 mm --> 16.28 +/- 2.23 mm, respectively) were gradually decreased, and finally returned to preoperative value (11.29 +/- 1.67 mm, 13.59 +/- 2.01 mm, respectively). In SynFix-LR(R) group, immediately increased disc and IVF heights (9.60 +/- 2.82 mm --> 15.61 +/- 0.62 mm, 14.01 +/- 2.53 mm --> 21.27 +/- 1.93 mm, respectively) were maintained until the last follow up (13.72 +/- 1.21 mm, 17.87 +/- 2.02 mm, respectively). The changes of IVF width of each group was minimal pre- and postoperatively. Solid arthrodesis was observed in 11 patients in Stabilis group (11/13, 84.6%) and 13 in SynFix-LR(R) group (13/15, 86.7%).

Conclusion: ALIF using stand-alone cage could assure good clinical results in the treatment of symptomatic lumbar IFS in the mid-term follow up. A degree of subsidence at the operated segment was different depending on the device type, which was higher in Stabilis(R) group.

Keywords: Anterior approach; Lumbar foraminal stenosis; Lumbar interbody fusion; Stand-alone cage.

Fig. 1

Stabilis® (Stryker, Kalamazoo, MI, USA). It is a titanium implant, which is made of an anatomically friendly frame with a bone graft delivery unit.

Fig. 2

SynFix-LR® (Synthes Bettlach, Switzerland). It is consisted with two distinct parts; Polyetheretherketone frame and titanium anterior plate. Diverging locking screws penetrate the vertebral body close to the anterior rim offering stability.

Fig. 3

Measurement of radiological parameters at the operated segement. Disc height is defined as an average value of A (anterior disc height) and B (posterior disc height), C : intervertebral foraminal height, D : intervertebral foraminal width.

Fig. 4

Bar graphs showing the clinical results according to the type of prosthesis.

Fig. 5

Line graphs showing the change of radiological parameters of the segment during follow up. DH : disc height, FH : intervertebral foraminal height, FW : intervertebral foraminal width, ST : Stabilis® group, SY : SynFix-LR® group.