|Year : 2019 | Volume
| Issue : 2 | Page : 122-127
Clinico-radiological outcomes of single level TLIF using local morselized impacted bone graft vs cage with local bone graft
Sandeep Gokhale, Aditya Anand Dahapute, Sandeep Sonone, Saurabh Muni, Sai Gautham, Shubhanshu Bhaladhare
Department of Orthopaedics, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||23-Jul-2019|
Dr. Aditya Anand Dahapute
Department of Orthopaedics, Seth G.S. Medical College and KEM Hospital, Ortho Office, 6th Floor, New Building, Mumbai - 400 012, Maharashtra
Source of Support: None, Conflict of Interest: None
Aim: To study the fusion rate and clinical outcome of transforaminal lumbar interbody fusion (TLIF) with cage and TLIF with local morselized graft. Design: Retrospective. Materials and Methods: We retrospectively studied thirty patients who received the TLIF with local morselized impacted bone grafts without a cage (Group 1), thirty patients who received TLIF with local bone graft combined with one titanium cage with 4° lordosis (Group 2) with an average follow-up of 15 months. Patients were clinically evaluated at regular intervals along with radiographs. Computed tomography (CT) scans were also performed at 6 months and 1 year after surgery. Functional outcome was assessed using the Modified Oswestry Score (MOS) and Visual Analog Score (VAS) for back pain preoperatively, immediate postoperatively, and at 3 months, 6 months, and 1 year. Statistical Analysis Used:P < 0.05 was taken as the level of significance. SPSS software version 17 was used for analysis. Results: The VAS scores in group 2 (TLIF with cage group) at preoperatively, 3 months, 6 months, and at the end of 1 year improved significantly from 8.47, 3.53, 2.27, and 1.60, respectively; in TLIF without cage group (Group 1), it improved from 8.73, 4.00, 2.53, and 1.47, respectively. The MOS improved from 75.87 preoperatively in the TLIF with cage group (Group 2) to 34.53 at the end of 1 year. In the TLIF without cage group (Group 1), it improved from the preoperative P value of 75.47 to 35.30. Fusion was present in all the cases radiologically. Brantigan criteria were used to assess fusion on CT scan. The mean lordotic angle in the cage group decreased from 17.3° immediately after surgery to 16.5° at 1 year. The mean change was 0.80° in Group 1 (no cage), and the mean lordotic angle decreased from 16.5° immediately after surgery to 14.4° in group 2 (with cage) at 1 year. Conclusion: If we compare clinical and radiological results between the local bone graft with a cage and the morselized impacted bone graft groups, for one-level TLIF, the difference is not significant.
Keywords: Cage, interbody fusion, local morselized impacted bone graft, transforaminal lumbar interbody fusion
|How to cite this article:|
Gokhale S, Dahapute AA, Sonone S, Muni S, Gautham S, Bhaladhare S. Clinico-radiological outcomes of single level TLIF using local morselized impacted bone graft vs cage with local bone graft. Indian Spine J 2019;2:122-7
|How to cite this URL:|
Gokhale S, Dahapute AA, Sonone S, Muni S, Gautham S, Bhaladhare S. Clinico-radiological outcomes of single level TLIF using local morselized impacted bone graft vs cage with local bone graft. Indian Spine J [serial online] 2019 [cited 2019 Oct 22];2:122-7. Available from: http://www.isjonline.com/text.asp?2019/2/2/122/263278
| Introduction|| |
Transforaminal lumbar interbody fusion is one of the surgical options for degenerative lumbar spine instability, recurrent disc herniation, and spondylolisthesis. Transforaminal lumbar interbody fusion (TLIF) provides immediate anterior-column support, offers a large surface area for osseous fusion, and places the interbody graft under a compressive load enhancing the fusion and maintaining disc height.
In performing TLIF usually autologous iliac crest bone graft is used to obtain the required amount of bone for fusion. Recently, some graft substitutes or autograft expanders such as allografts, ceramics, demineralized bone matrix, and recombinant human bone morphogenetic proteins 2 and 7 have been advocated.
Iliac crest bone harvest is associated with complications ranging from 1% to 39%, which include hematoma, infection, prolonged chronic pain, and sensory deficit.,, Synthetic materials are popular for an infinite supply, easily being sterilized and stored, and have a decreased risk of disease transmission. However, these gains must be weighed against the significantly increased cost of synthetics and poor osteoinduction.
The bone grafts used for interbody fusion should have osteogenic capacity and good mechanical strength. Autologous iliac grafts have good osteogenic capacity, but they are associated with complications such as donor-site pain, more blood loss, and increased chances of infection. Allogeneic bone graft is another alternative, but it carries a risk of infection.
In this study, we performed unilateral TLIFs using a single titanium cage in one group (Group 2) and morselized impacted local bone graft in another group (Group 1). Each cage was filled with a local morselized bone graft that was obtained during posterior decompression from lamina and spinous process. We retrospectively analyzed the clinical and radiographic outcomes of this technique.
| Materials and Methods|| |
We retrospectively studied sixty patients treated with TLIF between July 2014 and July 2016 at an average follow-up of 15 months. Patients with Grade 1 and 2 degenerative spondylolisthesis and lumbar spinal stenosis associated with low back pain and leg pain at L4–L5 or L5–S1 were included in this study. The symptomatic indications included disabling back pain that resulted in lifestyle alterations and failure of nonoperative treatment for more than 6 months. Patients with high-grade spondylolisthesis, infection, severe osteoporosis, previous spinal fusion operations, and fusion at more than one level were excluded from the study. While 31 patients received the TLIF with local morselized impacted bone grafts without a cage (Group 1), 33 patients received TLIF with local bony graft combined with one titanium cage (Group 2), However, one patient from Group 1 and three patients from Group 2 were lost to follow-up.
Written consent was obtained from the patients for participating in the study. The research was approved by the ethical committee.
Patients were placed prone, and the posterior elements of the spine were exposed through a standard midline incision.
A subperiosteal dissection of the paraspinal muscles was performed. Pedicular screws were inserted under fluoroscopy. Laminectomy with or without facetectomy was performed. Unilateral facetectomy was performed in order to expose the intervertebral foramen. The exiting nerve root was identified just inferior to the upper pedicle and was protected throughout the procedure. The disc space was entered through a unilateral transforaminal approach, and a thorough discectomy was performed with curette to remove the cartilage. Disc space was distracted during disc space preparation. Bone graft obtained from lamina, spinous process, and facets was morselized and used as graft.
For patients in Group 1 (no cage), local morselized bone graft was punched in and packed. This continued impaction of the bone graft led to closer contact between the bone and bone graft bed and provided sufficient biomechanical strength.
Those in Group 2 received titanium cage. The cage was also filled with local bone graft. A disc spanner was used to measure the intervertebral height and thus determine appropriate cage size. The anterior portion of the disc space was then packed with autograft obtained from the laminectomy, and then the cage was placed into the middle third of the disc. Once the cage was inserted, the distraction was released. Compression was applied to the pedicular screws along the rods; this served to restore lumbar lordosis. The transverse processes were decorticated, and bone grafting was done for posterolateral fusion. The wound was irrigated and closed in a standard fashion. Patients were clinically evaluated at regular intervals along with radiographs.
All patients were mobilized about 1 week postoperatively with lumbosacral brace. Anteroposterior and lateral images were performed pre- and post-operatively, and computed tomography (CT) scans were also performed at 6 months and 1 year after surgery.
Functional outcome was assessed using the Modified Oswestry Score (MOS) and Visual Analog Score (VAS) score for back pain regularly on follow-up and preoperatively.
The lateral plain radiographs taken preoperatively, immediately postoperatively, and at the last follow-up were compared for the radiological assessment. Although the radiopaque titanium cage made it difficult to assess whether bony union was achieved, the local morselized bone graft impacted anterior to the cage allowed for directly evaluating the bony union. In other words, we carefully looked for bone bridging and radiolucency around the cage and the metal screws and any evidence of instability on the flexion-extension lateral radiographs for assessing the bony fusion. Fusion was assessed on both CT scan and X-ray.
Brantigan criteria [Table 1] were used for assessment of fusion on CT scan.
Grade 4 and 5 was considered as fusion. Nonunion was defined as disruption of the trabecular continuity, the appearance of instability on the flexion-extension radiographs, and ≥1 mm radiolucency around the screws and cage. Instability was considered present when ≥3° of posterior angular formation was observed on the lateral radiographs and ≥2 mm of displacement of the vertebral body and cage movement occurred. Fusion was considered to be obtained when bony trabecular continuity and bone bridging from the graft to the adjacent vertebral bodies was present in the intervertebral space during the follow-up examinations, no instability on the flexion-extension radiographs, and no radiolucency around the cage and screws were observed. Delayed union was diagnosed when all of the definitions of solid union were met despite the disruption of the trabecular continuity and evidence of nonunion were not observable.
Lordotic angle was also measured for the instrumented vertebral level both immediate postoperatively and at last follow-up.
We could not perform CT scan of four patients, but all of them had fusion evident on X-ray at 12 months. There was no instability on flexion-extension X-rays. Hence, decision was made to include these cases in our study.
| Results|| |
The clinical outcomes were as follows:
[Table 2] shows demographic distribution in each of the study groups. The VAS scores in the TLIF with cage group (Group 2) at preoperative, 3 months, and 6 months and at the end of 1 year improved significantly from 8.47, 3.53, 2.27, and 1.60, respectively. In the TLIF without cage group (Group 1), it improved from 8.73, 4.00, 2.53, and 1.47 at preoperative, 3 months, 6 months, and at the end of 1 year, respectively [Table 3] and [Figure 1].
The MOS improved from 75.87 preoperatively in the TLIF with cage group (Group 2) to 34.53 at the end of 1 year. In the TLIF without cage group (Group 1), it improved from the preoperative value of 75.47 to 35.30 [Table 4] and [Figure 2].
The radiological outcomes were as follows: in the TLIF with cage group (Group 2), there were twenty cases of union and ten cases of delayed union at the end of 6 months. Union was seen in all the thirty cases at follow-up of 1 year.
In the TLIF without cage group (Group 1), there were 16 cases of solid union and 14 cases of delayed union at the end of 6 months, and complete union was seen in all the thirty patients at follow-up of 1 year [Table 5] and [Figure 3] and [Figure 4].
|Figure 3: (a) Preoperative X-ray of degenerative spine. (b) Postoperative X-ray showing L4–L5 transforaminal lumbar interbody fusion done with cage. (c) Postoperative computed tomography scan showing interbody fusion|
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|Figure 4: (a) Preoperative X-ray of degenerative spine with L5–S1 instability. (b) Postoperative X-ray showing L5–S1 transforaminal lumbar interbody fusion done with local bone graft. (c) Postoperative computed tomography scan showing interbody fusion at 1 year|
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The P value of radiological results (fusion) in both the groups at the end of 1 year were >0.05 (P = 1), showing similar results in them.
The mean lordotic angle in the cage group (Group 2) decreased from 17.3° immediately after surgery to 16.5° at long-term follow-up examination. The mean change was 0.80°. In Group 1 (no cage), the mean lordotic angle decreased from 16.5° immediately after surgery to 14.4° at long-term follow-up. The mean change in this group was 2.1°. The difference in mean change in lordotic angle for each group was not statistically significant (P = 0.415).
There were no cases of nonunion.
The mean duration of surgery was 221.5 min (range 140–320 min) for single-level fusion in Group 1 (no cage) and 210.1 min in Group 2 (with cage) (range 151–310 min).
The mean hospitalization period was 14.5 days (range, 7–28 days).
Qualitative data such as sex and union were represented in the form of frequency and percentage. Association between qualitative variables was assessed by Chi-square test. Quantitative data such as age and VAS score were represented using mean ± standard deviation. Age comparison between the two groups was done using unpaired t-test, while VAS and MOS were compared using Mann–Whitney test. P < 0.05 was taken as statistical level of significance. SPSS software version 17 (UNICOM Systems, Inc., Mission Hills, California) was used for most of the analyses, and Microsoft Excel 2010 was used for graphical representation.
| Discussion|| |
Interbody fusion is one of the most common types of vertebral body fusions, and it is the most sound biomechanical technique. Inventions of many cages were prompted due to the popularity of interbody fusion., In posterolateral fusion, there is a risk of muscular fibrosis caused by the extensive release of muscles adjacent to the transverse process and increased blood loss and postoperative wound infection due to increased operative time. On the other hand, interbody fusion was advantageous for increasing the fusion rate with no need for extensive muscle release around the transverse process, graft was under compression force, and there was high rate of fusion.,, 360° fusion has a lesser rate of pseudoarthrosis.
In TLIF, iliac crest is considered as an ideal source of graft. An iliac crest bone graft facilitates rapid bone union, but increases the risk of donor-site pain, infection, excessive blood loss, pelvic fracture, an additional skin incision, and lengthy operative time. In contrast, a local bone graft consisting of the lamina as well as articular and spinous processes obtained from decompression can shorten the operative time and reduce blood loss. Various studies had reported that local bone chips obtained from decompression can be used as bone grafts which demonstrate comparable fusion rates with the iliac crest., Therefore, local bone has already become a frequently used bone graft substitute instead of iliac crest.
However, a local bone graft has its own disadvantages due to its poor bone quality, as compared with the iliac crest bone graft and hence poor bony fusion. Furthermore, it does not provide mechanical support if not impacted. Studies have reported greater improvement and better maintenance of disc space, vertebral height, and the absence of collapse with the cage compared to the no cage group. Abdul reported that the increment in disc height and VAS score was significantly better in the cage group compared to the bone graft group. In this study, only local bone graft was used, which is less rigid and leads to collapse, pain, and disability. However, the morselized bone graft utilized in the present study is different from the local bone graft reported by Abdul. In our study, continued impaction resulted in close contact between bone and bone graft bed, which gave sufficient biomechanical strength.,
In a similar study by Lv et al., the authors concluded that there were no significant differences in clinical and radiological results between the local bone graft with a cage and the morselized impacted bone graft groups, for one-level TLIF. In this study, the mean disc height-to-vertebral body ratio was restored and preserved in the morselized impacted bone graft group, which was not significantly different from the cage group.
In our study, transplanting a bony graft anterior to the cage could enlarge the intervertebral contact surface; the graft anterior to the cage was an indicator of bony union in spite of the radiopacity of the titanium cages.
As an interbody fusion device, the cage is often used for interbody fusion in order to restore the disc height in cases with collapsed degenerated discs as well as to provide immediate anterior load-sharing support with good bony union rate. However, there exist disadvantages of cages such as it decreases the surface area for bony union, which causes low union rate; retropulsion and migration; and collapsed end plates.
In a study by Hu et al., the authors reported that lumbar lordosis and mean disc height-to-vertebral body ratio can be restored and preserved after surgery using local bone graft without a cage in patients who undergo posterior lumbar interbody fusion (PLIF). In a study by the same authors, it was shown that the mean disc height-to-vertebral body ratio was restored and preserved in both of the groups (with cage (Group 2) and without cage (Group 1)). In our study, lordosis angle immediately after study and after 1 year of follow-up was not statistically different in both the groups.
Cost of cage also increases the cost of surgery. Morselized impacted bone graft can supply sufficient biomechanical strength. In our study, we used morselized bony graft, which was impacted and thus increased its biomechanical strength. The morselized impacted bone grafts also enlarged the bone contact area.
Patil et al. showed that good fusion rate can be obtained using corticocancellous laminectomy bone chips alone in patients with single-level instrumented PLIF. Miura et al. found that the fusion rate was 72.4% after 6 months and 100% after 12 months when patients underwent PLIF with only local bone. Hashimoto et al. reported a fusion rate of 100% at 2 years after PLIF with local bone mixed with apatite–wollastonite glass ceramics grafted in a single intervertebral space.
In our study, although the results obtained in both the groups were comparable, we believe that local morselized bone graft without a cage should be preferred over a cage because it will reduce the cost by using local bone graft without a cage, and titanium cage is a foreign material to the human body, so there is still a potential risk of foreign body reaction and infection.
| Conclusion|| |
If we compare clinical and radiological results between the local bone graft with a cage and the morselized impacted bony graft groups for one-level TLIF, the difference is not significant. However, using only morselized impacted local bone graft will not only decrease the cost of surgery, but also decrease the complications of cage. Hence, morselized impacted local bone graft is a good option for single-level TLIF.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]