Inserting pedicle screws in lumbar spondylolisthesis - The easy bone conserving way

Abstract

Background: Pedicle screw fixation in high grade lumbar listhetic vertebral body has been nightmare for Orthopaedic and spine surgeons. This is because of abnormally positioned listhetic pedicles and non-visualization of pedicle in conventional image intensifier (C-Arm). This results into increased surgical time, more blood loss, radiation exposure and more chances of infection. To overcome this problem, we have devised a new Technique of putting of pedicle screw fixation in listhetic vertebrae.

Methods: Total 20 patients of average age of 42 (25-56) were included during 2010 to 2015. Listhesis was classified according to etiology, Meyerding grading and DeWald modification of Newman criteria used for assessment of severity for spondylolisthesis on standing X-ray lumbosacral spine. Patients satisfying following criteria were considered for surgery. Age more than 20 years, with single involvement of either L4-5/L5-S1, high grade spondylolisthesis (≥ 50% Meyerding grade), unresolving radiculopathy, cauda equina syndrome or pain with and without instability not relieved by 6 months of conservative treatment. According to Meyerding radiographic grading system,10 patients were of type II and 8 of type III and 2 of type IV. Treatment given was pedicle screw fixation, reduction of listhesis vertebra and spinal fusion with our technique. PLT was done in 10 cases and transforaminal lumbar interbody fusion (TLIF) in the other 10 cases.

Results: Mean follow up duration was 2 years (range 1.3-3.3 year). The average preoperative LBP VAS of low back pain were 6.7 and average LP VAS for leg pain 5.7. Postoperatively at final follow up there was reduction of LBP VAS to 2.2 and LP VAS to 0.5. There was rapid reduction in their LBP VAS in first two visits at 4 weeks and in LP VAS in first three visits at 8 weeks. The pain-free walking distance improved significantly. The average pre-operative ODI score was 51.4, improved to 18.6 postoperatively. There was no difference in above scores between PLT and TLIF.

Conclusion: Our surgical technique used for high grade spondylolisthesis is safe, cost-effective, bone-preserving, reliable, and reproducible for high grade Lumber spondylolisthesis.

Keywords: Insertion technique; Pedicle screw; Spondylolisthesis.

Fig. 1

(a) Anterior–posterior view and lateral view of grade IV, L5-S1 anterolisthesis, (b) C-arm image showing radiolucent starter inserted at base of pedicle in lateral view which is progressively angled in direction/axis of pedicle, (d) per-operative image shows manual insertion of probe on both sides of pedicle, (e) probe is angled in the line of pedicle in lateral view, (c, f) C-arm angled cephalad to make it collinear to the radiolucent probe for taking a true anterior–posterior view showing pedicle outline.

Fig. 2

(a) Hammering of radiolucent starter in the direction of pedicle in lateral view. (b) Pedicle probe inserted in the pedicle seen on angled AP view. (b) Arrows pointing towards the pedicle sound centred in pedicle in anterior–posterior view. (c) Pedicle sound centred in pedicle in anterior–posterior view. Anterior–posterior view of lumbosacral spine-post pedicle screw insertion highlighting the efficacy of our angled AP view, (d) shows standard AP view with non-visualisation of pedicle. (e and f) Progressively angled AP view show clear demarcation of pedicle outline with screw in situ.

Fig. 3

(a and b) Anterior–posterior and lateral view of grade III L5-S1 isthmic spondylolisthesis pre-operatively. (c and d) Anterior–posterior view and lateral view of anterolisthesis showing almost full correction of the slip post-operatively. Sacral screws were inserted by two described techniques one in divergent and the other convergent manner. (a) Anterior–posterior X-ray view and flexion–extension lateral view showing increase slip in a case of grade II degenerative listhesis, (b) sagittal MRI section of spondolisthesis, (c) axial section MRI of degenerative L4 L5 spondylolisthesis, (d) anterior–posterior and lateral view of degenerative spondolisthesis post operatively.

Fig. 4

(a) Preoperative X-ray of grade IV isthmic spondylolisthesis – 80% (b and c) postoperative X-ray showing reduction to grade II – 25%.

Fig. 5

(a) Post-operative CT scan sagittal formulation and axial section of above grade IV isthmic spondylolisthesis. Sagittal CT sections show reduction of anterolisthesis to Meyerding grade II and neural formina free from any impingement; axial CT sections shows no pedicle breach and spinal canal free from any impingement. (b) CT section shows slip angle 7.2°; CT section shows slip reduced to Meyerding grade I, measurement of slip angle, sacral inclination 35.9°, pelvic incidence 61°, sacral slope, 41°, pelvic tilt 20° (1 year post op).

Fig. 6

(a and b) Anterior–posterior and lateral view of anterolisthesis post-operatively after 18 months showing PLT graft (autologous and artificial) compared to preoperative X-ray films. (c–f) Line diagram of our technique in clockwise direction-localise pedicle axis on lateral view with a starter – tilt the C-arm cephalad in line with the for a true angled AP view of pedicle – insert screws.

Fig. 7

TLIF series (a) L 5–S1 listhesis Grade II. (b) L4–L5 listhesis.

Fig. 8

TLIF series (a) degenerative listhesis grade II preoperative MRI. (b) Flexion–extension view show listhesis increasing to high grade II with measurements of pelvic incidence, sacral slope and pelvic tilt preoperatively. (c) Postop X-ray with 2level fixation and TLIF.