Dynamization-Posterior Lumbar Interbody Fusion for Hemodialysis-Related Spondyloarthropathy: Evaluation of the Radiographic Outcomes and Reoperation Rate within 2 Years Postoperatively

Abstract

Study design: Clinical case series.

Purpose: This study aimed to report dynamization-posterior lumbar interbody fusion (PLIF), our surgical treatment for hemodialysisrelated spondyloarthropathy (HSA), and investigate patients' postoperative course within 2 years.

Overview of literature: HSA often requires lumbar fusion surgery. Conventional PLIF for HSA may cause progressive destructive changes in the vertebral endplate, leading to progressive cage subsidence, pedicle screw loosening, and pseudoarthrosis. A dynamic stabilization system might be effective in patients with a poor bone quality. Thus, we performed "dynamization-PLIF" in hemodialysis patients with destructive vertebral endplate changes.

Methods: We retrospectively examined patients with HSA who underwent dynamization-PLIF at our hospital between April 2010 and March 2018. The radiographic measurements included lumbar lordosis and local lordosis in the fused segment. The evaluation points were before surgery, immediately after surgery, 1 year after surgery, and 2 years after surgery. The preoperative and postoperative radiographic findings were compared using a paired t-test. A p-value of less than 0.05 was considered significant.

Results: We included 50 patients (28 males, 22 females). Lumbar lordosis and local lordosis were significantly improved through dynamization- PLIF (lumbar lordosis, 28.4°-35.5°; local lordosis, 2.7°-12.8°; p<0.01). The mean local lordosis was maintained throughout the postoperative course at 1- and 2-year follow-up (12.9°-12.8°, p=0.89 and 12.9°-11.8°, p=0.07, respectively). Solid fusion was achieved in 59 (89%) of 66 fused segments. Solid fusion of all fixed segments was achieved in 42 cases (84%). Within 2 years postoperatively, only six cases (12%) were reoperated (two, surgical debridement for surgical site infection; two, reoperation for pedicle screw loosening; one, laminectomy for epidural hematoma; one, additional fusion for adjacent segment disease).

Conclusions: Dynamization-PLIF showed local lordosis improvement, a high solid fusion rate, and a low reoperation rate within 2 years of follow-up.

Keywords: Destructive spondyloarthropathy; Dynamic stabilization; Dynamization; Hemodialysis; Posterior lumbar interbody fusion.

Fig. 1

(A) Postoperative radiograph of the lumbar spine after conventional posterior lumbar interbody fusion for a hemodialysis-related spondyloarthropathy patient. (B) Postoperative lateral radiograph of the lumbar spine three months after surgery. (C) Postoperative radiograph of the lumbar spine six months after surgery showing that progressive destructive changes in the vertebral endplate have led to progressive cage subsidence and pedicle screw loosening.

Fig. 2

Measurements on radiograph of lumbar lordosis and local lordosis in the fused segment.

Fig. 3

Model of the dynamization–posterior lumbar interbody fusion procedure. The implant system used was the MYKRES Spinal System (Teijin Nakashima Medical, Tokyo, Japan). The rods are placed with lateral connectors onto the pedicle screws. Although one side of the connector is fixed by a set-screw as usual, the other side is set free (arrowheads), allowing the movement of relevant vertebra. A stopper (arrows) is placed next to each free connector to block opening of the intervertebral space.

Fig. 4

Postoperative course of lumbar lordosis and local lordosis of the fused segment. Lumbar lordosis at 1- and 2-year follow-up had improved significantly compared to that immediately after surgery. Local lordosis did not change significantly. NS, not significant. ^*p<0.05. ^**p<0.01.

Fig. 5

Representative case presentation. (A) Magnetic resonance imaging showing canal stenosis at L3/4. (B) Preoperative lateral radiograph showing degenerative spondylolisthesis at L3/4. (C) Postoperative lateral radiograph showing dynamization–posterior lumbar interbody fusion at L3/4. (D) Postoperative lateral radiograph after 2 years showing bone union with maintained local lordosis. A gap appeared between the stopper and connector (arrow).

Fig. 6

The illustration of conventional posterior lumbar interbody fusion (PLIF) procedure and dynamization–PLIF procedure reproduced from [28] with permission. (A) Model of the conventional PLIF procedure. When the anterior element is shortened due to cage subsidence and pedicle screw loosening, it causes local kyphosis. (B) Model of the dynamization–PLIF procedure. As the posterior element of the subsiding vertebra is allowed to slide along the rods, sagittal alignment is preserved.