Comparative study between transpedicular screws fixation with and without interbody fusion using cages in lumbar spondylolisthesis

INTRODUCTION

Spondylolisthesis describes the anterior or posterior displacement of a vertebra or the vertebral column in relation to the vertebrae below and has been recognized as a disorder characterized by a visible lumbosacral deformity, slipped vertebrae and fractures or other deformities of the pars interarticularis since 1782. The incidence of spondylolisthesis in the general adult population is 4–8%, varying depending on the race, age and sex of the population sample. ¹

The most widely recognized classification system subdivides spondylolisthesis into isthmic, degenerative dysplastic, traumatic and pathologic type in addition to the postsurgical type.²

Most cases with spondylolisthesis are asymptomatic. Although the various types of spondylolisthesis differ as regard to cause, age, sex and pathology, several clinical presentations are common to all types including back pain, radicular pain, neuroclaudication pain, deformity kyphosis or scoliosis and gait disturbance).³

Degree of slip “meyerding grading system”.Theantero-posterior diameter of the superior surface of the vertebra divided into quarters:

Grade I: Less than 25% slip, Grade II: From 25-50% slip, Grade III: From 50-75% slip, Grade IV: More than 75% slip ⁴.

Standing lateral radiographs are the preferred method of evaluating slippage. Lateral X-rays of the spine help to establish the diagnosis and degree of spondylolisthesis. Dynamic radiographs, such as the hyperextension and flexion views, may detect occult mobility, Recently, MRI is also helpful in defining the causes of radiculopathy⁵.

Many cases of isthmic spondylolisthesis can be managed conservatively. Surgery is indicated in resistant cases, operative intervention for spondylolisthesis employs variable combinations of neural decompression, fusion and internal fixation⁶.

The goals of surgery are relief of pain, improvement or resolution of neurologic deficit and improvement in the quality of life. Decisions about surgery are usually based not only on the nature of the localized pathology and associated symptoms and disability, but also on other factors such as the patient’s occupation, athletic or recreational activity, and socio-economic situation⁷.

The aim of this study is to evaluate clinical and radiological outcome in cases of 1st and 2nd grade of degenerative lumbar spondylolisthesis treated with transpedicular fixation with or without interbody fusion by lumbar cage.

PATIENTS AND METHODS

Prospective and retrospective study will be carried on 40 patients presented with 1st and 2nd grade degenerative spondylolisthesis.

The inclusion criteria were: 1) patients with 1st and 2nd grade degenerative lumbar spondylolisthesis; 2) Patients who will agree to join the study according to the ethical considerations and consent will be taken from them.

However, exclusion criteria were: 1) Patients with other types of lumbar spondylolisthesis; 2) Patients with other grades of lumbar degenerative spondylolisthesis (3rd and 4th grades); 3) patients with other spine pathology (lumbar fracture, disc prolapse); 4) patients respond to conservative treatment

Preoperatively, the work of assessment included history taking, neurological examination and calculation of Oswestry Disability Index (ODI) and Visual Analogue Score (VAS) for pain assessment. In addition, imaging studies included MRI, computed tomography (CT) and dynamic plain X-ray.

The surgical treatment was carried out under general anesthesia with preoperative antibiotic prophylaxis in a prone position on spinal frame, with the abdomen free and the spine flexed to open the inter-laminar spaces. The surgical technique continues as described by Alexander, 1995.⁸

The operative data included the affected site, the intraoperative blood loss, and mode of fixation used. Postoperatively, there was assessment of pain and neurological disability if present. In addition, any intraoperative or post-operative complications were documented.

In this study we followed patients immediate postoperative and at 3th and 12th month postoperative where we evaluated them by clinical and radiological means.

Ethical considerations:

Lumber laminectomy and disc removal with lumbar pedicle screw fixation with or without inter body fusion consent includes discussing the operative procedure with the patient with its intended benefits of pain relief and possible improving function and symptoms of walk.

Discussing neurological deterioration, complications such as (Dural tear, infection, hematoma, nerve root injury).

The patient confidentiality and his/her right for withdrawal at any time was assured. The study protocol was approved by the local institutional review board (IRP) of Al-Azhar Faculty of Medicine.

Statistical analysis:

Statistical analysis were peformed using Stata/IC version 16.1 for Windows (StataCrop, LLC, College Station, TX, USA). Descriptive statistics for quantitative data were expressed in tables as the mean ± SD, while qualitativedata were expressed as number and percentage. We checked the normality of continuous data using Shapiro Walk test. We used paired Student's t-test to compare VAS for back pain, VAS for radical pain before and after operation. Unpaired Student's t-test was used to compare surgical outcomes between both groups. Chi square test was used to examine the differences between categorical variables. P-value was considered significant if < 0.05.

Results

The present trial included 40 subjects with various degrees of Spondylolysthesis; They were divided into 2 main groups: group A : TPF (Transpedicular fixation) and group B: TPIF (Transpedicular with interbody fusion).

The mean age of group A was 57.85± 5.49 years ranging between 46 and 60 years. However, the mean age of group B was 56.55 ± 6.63 years, ranging from 44 to 67 years.

Out of 20 patients in group A, 14 (70 %) patients were females, and the others were males. While in group B there were 13 (65 %) females, and the others were males.

Only one patient in our study had two levels of spondylolisthesis in group A. while all patients in group B had only one level of listhesis.

 In group A only two patients had Grade II listhesis, and the others had Grade I listhesis. While in group B only one patient has Grade II listhesis and other patients had Grade I listhesis.

In group A the mean preoperative back pain visual analogue score (VAS) was 7.25. The same as in group B. The mean preoperative leg (VAS) of the studied patients in group A was 5.2. While patients in group B had mean score 4.75. the mean preoperative ODI of the studied patients in group A was 72.4 while in group B it was 78.7 .In addition, there was significant decrease in VAS and ODI at 3 months postoperatively (table2 ).

 In group A, estimated blood loss was 567.5 cm3 which is lower than that in group B 800 cm3.In the group A, there was only one patent (5%) had a dural tear, on the other hand the group B had five complications (20%): three dural tears, one (5%) root injury and one deep wound infection.

As regard the postoperative fusion rate, in group A 14 (70%) out of total 20 patient achieved grade II, however the remaining six patients (30%) achieved grade III and no patients achieved grade I. On the other hand, nine patients (45%) in group B achieved grade I, 11 patients (55%) achieved grade III.

Case presentation:

Figures 1 and 2 represented pre- and post-operative images for a 48 year old female patient with history of slowly progressive back pain and bilateral claudication pain with failure of conservative measures more than 6 months. Pre-operative x-rays and MRI were done showing L4-L5 Spondylolysthesis.

Patient underwent L4-5 fixation with pedicle screws with interbody fusion by PLIF cage.

The patient improved clinically as determined by ODI and VAS for back and leg pain. Post-operative x-rays of lumber spine was done showing rods and screws and cage in the proper site with no post-operative instability

Table 1: Demographic and Clinical Characteristics of Patients. TPF, trans pedicular fixation; TPIF, transpedicular with interbody fusion; VAS, visual analogue scale; ODI, Oswestry Disability Index. Data expressed as mean ± SD, frequency (percentage). *P value was considered significant if < 0.05

Table 2: Comparison of surgical outcomes between TPF and TPIF. TPF, trans pedicular fixation; TPIF, transpedicular with interbody fusion; VAS, visual analogue scale; ODI, Oswestry Disability Index; BP, back pain; RP, radical pain. Data expressed as mean ± SD, frequency (percentage). *P value was considered significant if < 0.05.