In current TLIF practice, the choice of the cage size is empirical and primarily depends on the case volume and experience of the surgeon. We used a self-made modified distractor handle in TLIF procedure with the goal of standardizing the intervertebral space tension and determining the proper cage size.
Lumbar interbody fusion (LIF) is the gold standard treatment modality for lumbar degenerative disease (LDD) [
Transforaminal LIF (TLIF), an alternative technique to ALIF and PLIF, was first reported by Blume [
TLIF is subject to some technical limitations. The entire removal of facet joints may cause recurrent low back pain and spinal deformity. Implantation of two cages is normally required to restore segmental alignment and achieve reliable fusion, although the use of a single cage has been reported [
In our spinal surgery unit, we have been replacing the conventional T-handle and spreader curette with a modified, scaled (0–6 N) distractor handle, with the goal of standardizing the intervertebral space tension and determining the proper cage size. The objective of this retrospective study was to examine the clinical and radiological results of TLIF performed with this modified distractor handle for the treatment of LDD in a midterm follow-up study.
The study protocol was approved by the Institutional Review Board at Zhongshan Hospital, Fudan University, Shanghai, China. This retrospective study included 45 patients (30 men; 15 women mean age, 53 years; range, 40–73 years) with radiographically documented LDD who were consecutively hospitalized and scheduled for elective unilateral, instrumented TLIF with the modified distractor handle (Figures
Conventional T-handle (a) and the modified, scaled distractor handle (b) used for the selection of cage size with a tension scale of 0–6 N from right to left, 1 N per scale (c).
Routine perioperative medical evaluation was performed in accordance with the patient’s physical status, which was classified by the system of the American Society of Anesthesiologists. In no patient was TLIF contraindicated by any medical or surgical condition. LDD and concomitant lumbar conditions were confirmed by anteroposterior and lateral (flexion and extension) lumbar spine radiography, computed tomography (CT), and magnetic resonance imaging. Complicating lumbar conditions were identified in all patients, which included the following: concomitant spinal stenosis with lumbar instability in 25 patients, involving a single segment (
Unilateral instrumented TLIF was performed
A preliminary study was done to measure the intervertebral space distraction tension in this study. Briefly, following endplate dissection the intervertebral space was distracted using the T-handle and an appropriate-sized cage was placed. Then the self-made modified, scaled (0–6 N) distractor handle was used to measure the intervertebral space tension, 1 N per scale. The distraction tension turned out to be 2–4 N (median, 3 N) in the great majority of patients. In subsequent experiment, the self-made modified distractor handle was used to measure the IVDSH for the selection of proper cage size, with the distractor handle tension maintained at 2 to 4 N (median, 3 N), as determined by the preliminary results (Figures
The self-made modified distractor handle was used to measure the intervertebral space height (a). The handle was spanned clockwise to increase the distraction tension, and cage size was determined with the distractor handle maintained at 2–4 N (b).
An appropriately sized polyether ether ketone (PEEK) cage (Stryker Corporation, Kalamazoo, MI) filled with excised local bones was inserted into the disc space to ensure a solid interbody fusion. Intraoperative lateral lumbar fluoroscopy was performed to confirm the cage position. The interbody graft was posteriorly compressed, and the pedicle screws were tightened unilaterally to restore lordosis. A drainage tube was placed prior to incision closure and removed at 24 to 48 hours after the operation. Patients were instructed to wear orthoses and start off-bed activities at 3 days after TLIF. Routine bed lumbodorsal muscle exercises were recommended.
Patients were followed up at outpatient clinics at 3, 6, 12, and 24 months after TLIF. Clinical outcomes were assessed in a self-reported manner with the Oswestry disability index (ODI) [
Bony fusion was defined as the presence of bone trabeculae across the interfaces between the cage and the endplates without any lucencies and the formation of a bony union between the superior and inferior endplates on the lateral plain radiographs [
All data were processed with the SPSS software package, version 19.0 (SPSS Inc., Chicago, IL). Data are reported as the mean ± standard deviation (SD) for ODI, VAS, and IVDSH results. Differences in the ODI, VAS, and IVDSH results between the baseline and follow-up times were compared by one-sample repeated-measures Student’s
The clinical results are shown in Table
Demographic and clinical data of LDD patients (
Age, year, mean (range) | 53 (40–73) |
Sex, M/F | 30/15 |
Concomitant lumbar conditions, |
|
Spinal stenosis with instability | 25 (55.6) |
Involving single segment | 19 (42.2) |
Involving two segments | 6 (13.3) |
Single-segment spondylolisthesis | 20 (44.4) |
Grade 1 | 11 (24.4) |
Grade 2 | 9 (20.10) |
Fused levels, |
|
L3-L4 | 7 (15.6) |
L4-L5 | 23 (51.1) |
L5–S1 | 25 (55.6) |
Operative time, min, mean (range) | 92.3 ± 34.5 (80–145) |
Volume of intraoperative bleeding, min, mean (range) | 120.4 ± 40.4 (95–160) |
Time length of postoperative hospitalization, |
7.3 (5–12) |
Duration of follow-up period, mo, mean (range) | 17.6 (12–24) |
LDD: lumbar degenerative disease; TLIF: transforaminal lumbar interbody fusion.
Postoperative recovery was uneventful for all patients. No patient complained of any postoperative neurological impairment. No delayed bleeding or surgical site infection was observed postoperatively. Wound drainage tubes were removed, and patients started off-bed activities while wearing orthoses as scheduled. The mean time of postoperative hospitalization was 7.3 days (5–12 days). The mean follow-up duration was 17.6 months (range, 12–24 months). No patient was lost to follow-up.
All patients completed the self-reported questionnaires as instructed. The ODI score decreased from
Improvements in ODI (a) and low back pain VAS (b) at 6 and 12 months after TLIF as compared to the baseline (Pre-TLIF). ODI, Oswestry disability index; VAS, visual analog scale.
No fixation device failure, cage migration, or endplate collapse was observed on the follow-up radiographs. The mean IVDSH increased from
Lateral radiographs of the lumbar spine in a 55-year-old male with degenerative spondylolisthesis. (a) Intervertebral space at the L4-L5 level was narrowed, as shown on preoperative radiography. (b) The intervertebral space was restored after TLIF.
Improvements in IVDSH at 3 days, and at 6 and 12 months after TLIF as compared to the baseline (IVDSH, intervertebral disc space height).
Follow-up three-dimensional CT scan revealing bony fusion at 12 months after TLIF. (a) Anteroposterior view; (b) lateral view; (c) coronal view; (d) lateral view with three-dimensional holographic reconstruction.
Currently, TLIF is well accepted as a treatment modality for various spinal disorders, including disc degenerative disease, spondylolisthesis [
No consensus has been reached regarding the measurement of IVDSH for determining cage size. The IVDSH is usually estimated based on the average of the anterior and posterior IVDSHs, or of the superior- and inferior-segment IVDSHs, from the preoperative lateral lumbar radiographs. In conventional TLIF, a nonscaled T-handle is used to twist the disc spanner for measuring the IVDSH. The determination of the intervertebral space tension depends on the experience of the surgeon. Therefore, the choice of cage size is more empirical than standardized, particularly for inexperienced spinal surgeons. In contrast, the use of the modified distractor handle can maintain a reasonable intervertebral space stress and preserve the bony endplate, thereby minimizing endplate bleeding and the risk of interbody subsidence. Our patients lost a mean blood volume of only 120 mL intraoperatively, substantially less than the ~300 mL of blood reported in previous studies [
Titanium cages have a much higher elasticity modulus than the vertebral body. Use of an oversized cage will increase the intervertebral stress and cause cage subsidence into the endplate, especially in osteoporotic patients [
Cage migration is the primary safety concern in TLIF, due to the serious neurological consequences if the cage protrudes posteriorly into the spinal canal [
This study has some limitations. First, as a retrospective, single-treatment-arm study, no comparative data were present, although we did compare our postoperative results with the baseline data and against findings in the literature. Second, this was a nonblinded study; therefore, the findings are subject to the investigator’s bias. However, the clinical results were assessed in a patient self-reported manner, and the radiological results were evaluated by an independent spinal surgeon who was not involved in the study. Finally, a midterm follow-up period was used, which is possibly not sufficiently long to evaluate the surgical results for such a chronic condition as LDD. A long-term clinicoradiological follow-up study is ongoing at our institute.
In conclusion, the use of a distractor handle in TLIF can decrease blood loss and operative time while showing favorable clinical improvements. The major benefit of this modification lies in the standardized and unified selection of cage size in TLIF. The proper choice of cage size using the modified distractor handle resulted in a zero rate of cage subsidence or migration and successful bony fusion in the midterm. This technique may be an effective and safe adjuvant method to TLIF for the treatment of LDD. Prospective, controlled, comparative studies are needed to evaluate the effectiveness and safety of TLIF using the modified distractor handle.
A. Rewuti and Z. Chen contributed equally to this work and all authors from the same department.
The authors declare that they have no financial and personal relationships with other people or organizations that can inappropriately influence their work; there is no professional or other personal interest of any nature or kind in any product, service, and/or company that could be construed as influencing the position presented in, or the review of, the paper entitled.