GOTHENBURG, Sweden — Japanese researchers found
bilateral pedicle screw fixation lead to greater reductions
in back pain, lower extremity pain and numbness in patients with degenerative
spondylolisthesis than treatment with unilateral screws.
Yasuchika Aoki, MD, and colleagues concluded from their
prospective, randomized controlled study that
unilateral pedicle screw fixation procedures were to
bilateral pedicle screw fixation for degenerative spondylolisthesis treated via
transforaminal lumbar interbody fusion (TLIF).
“TLIF with unilateral pedicle screws is less
invasive and cost effective to perform, Aoki of Toho University Sakura Medical
Center in Sakura, Japan, and Chiba Rosai Hospital in Chiba, Japan, said during
his presentation at the International Society for the Study of the Lumbar Spine
Annual Meeting 2011. “However, it resulted in less improvement of patient
He told Orthopedics Today, “The
unilateral fixation shows a lower fusion rate (87.5%) than the bilateral
fixation (95.7%), with no significant difference.”
Level 1 study
Aoki and his colleagues sought to determine whether
unilateral fixation was as effective as bilateral fixation for the treatment of
adult degenerative spondylolisthesis. They randomized 50 patients to undergo
one-level TLIF using either unilateral or bilateral pedicle screw fixation and
followed them for 2 years. Surgeons placed a single unilateral screw in the
unilateral cases. In the bilateral cases, Aoki said, surgeons used pedicle
screws on the bilateral side and implanted two interbody fusion cages.
These 2-year postoperative AP radiographs show a
patient’s one-level transforaminal lumbar interbody fusion (TLIF) done
with unilateral pedicle screw fixation.
Images: Aoki K
bony fusion 2 years postoperatively occurred in this single-level TLIF case
with unilateral pedicle screw fixation as depicted in a reconstructed CT
He and his team obtained more than 2-years follow-up for
94% of the cohort — 47 patients — with evaluation parameters
consisting of the 10-point visual analog scale (VAS) for back and lower
extremity pain, and lower extremity numbness and improvement in back disability
based on the lumbar Japanese Orthopaedic Association Back Pain Evaluation
Questionnaire (JOABPEQ) results.
Patient demographics were similar at the outset of the
Surgical time, clinical outcomes
Discussing the findings, Aoki said, “Our results
showed that mean surgical time was significantly shorter and blood loss was
significantly lower in the unilateral group, suggesting that unilateral pedicle
screw fixation is less invasive. Overall, subjective surgical outcomes showed
no significant differences between the two groups.”
During the discussion period, Aoki noted some bilateral
cases in the series took as much as 60 minutes longer to complete than the
unilateral cases, but eventually the difference in surgical time between the
two types of procedures was reduced to 30 minutes or 40 minutes.
Patients in both groups attained the same level of
walking ability postoperatively based on the JOABPEQ results, he said.
“At the final follow-up, VAS scores were
significantly lower for the bilateral group” than the unilateral group,
Aoki noted one limitation of the study is the number of
interbody fusion cages used, which may have influenced the clinical outcomes
and could have affected postoperative spinal stability.
“TLIF is generally recommended, but we just have to
pay attention. We may choose to unilaterally fuse patients, but we would like
to recommend [avoiding] using single pedicle screws and to be aware of the
limitations of unilateral pedicle screw fixation,” he said. – by
Susan M. Rapp
- Aoki Y, Yamagata M, Ikeda Y, et al. A prospective randomized
controlled study comparing unilateral and bilateral pedicle screw fixation in
transforaminal lumbar interbody fusions for degenerative spondylolisthesis.
Paper #P58. Presented at the International Society for the Study of the Lumbar
Spine Annual Meeting 2011. June 14-18. Gothenburg, Sweden.
- Yasuchika Aoki, MD, can be reached in the Department of Orthopaedic
Surgery, Toho University, Sakura Medical Center, 564-1 Shimoshizu, Sakura-city,
Chiba, 285-8741, Japan; email: email@example.com.
- Disclosure: Aoki has no relevant financial disclosures.
The strength of this study is that it was a prospective
randomized control trial. There was no information on the average age in the
two groups, no male to female ratio, and the degree of slip. Presumably these
were similar in the two groups. The data showed bilateral pedicle screw
fixation resulted in more improvement of back pain, lower extremity pain and
lower extremity numbness. However, there was no mention of the bony union rate
in the two groups. Presence or absence of union may be a cause for the
difference in back pain relief, and possibly relief of lower extremity
symptoms. Results of a longer follow-up period would be very useful.
John C.Y. Leong, FRCS, MCAS
Professor, Department of Orthopaedics & Traumatology, The University of
President, The Open University of Hong Kong
Orthopaedics Today Europe Editorial Board
Disclosure: Leong has no relevant financial disclosures.