To evaluate the technical feasibility and assess the clinical outcomes of tubular decompression (TD) in cases of multilevel lumbar canal stenosis operated through a single incision. TD has established itself in the surgical management of single level lumbar stenosis. Literature on performance of TD for multilevel stenosis through a single incision are non-existent.
All patients undergoing TD for multilevel lumbar stenosis through a single incision from January 2007 to January 2018 were included. Patient demographics, operative and peri-operative details were documented. Patient based clinical outcomes, namely Visual Analogue Scale (VAS) scale for back and leg pain and Oswestry Disability Index (ODI) were assessed.
Favorable tube trajectory and adequate decompression could be achieved through a single incision to decompress multiple levels. The VAS improved from mean 3±1.5 (2–5) to 2±0.8 (1–4) and 7±1.4 (4–9) to 2±1 (1–5) for back and leg pain respectively; while the ODI improved from a mean 44.6±8.6 (32–68) to 20.2±5.3 (16–42) at 3 months post-op and was maintained at 1±0.8 (1–4), 1.6±0.67 (1–3) and 19±2.9 (16–26) respectively at 2 years follow-up.
TD for multilevel stenosis done through a single incision is a feasible option with good to excellent results.
Lumbar canal stenosis (LCS) is one of the most common degenerative spinal disorders affecting the elderly with an incidence of 1.7%–8% [
After approval of the institutional review board of Bombay Hospital and Medical Research Centre (approval no. BHIRB7989), a retrospective analysis of prospectively collected data of patients undergoing TD for neurogenic claudication from January 2007 to January 2018 was performed. 502 patients with neurogenic claudication operated using tubular retractors by a single surgeon were identified. The inclusion criteria for the surgery was disabling pain due to neurogenic claudication unresponsive to a conservative line of treatment and who had an adequate clinico-radiological correlation with two-three level spinal stenosis on the MRI.
The patient was positioned on a radiolucent operating table on two well-padded horizontal bolsters and a silicone face support under general anaesthesia. The midline was marked with manual palpation of the spinous processes, in reference to which a para-median vertical line was drawn at a distance of 0.8–1 cm from the midline. An antero-posterior (AP) c-arm image to mark the midline may be necessary in extremely obese patients in whom the spinous processes were not palpable. A 20G spinal needle was then inserted through the para-median line such that the needle trajectory bisects the disc space of the involved level under c-arm control. The same spinal needle can be re-oriented in the trajectory/ies of the adjacent levels to verify the feasibility of decompression of those levels. This manoeuvre gives a sense of confidence to the operating surgeon about the feasibility of performing decompression of the adjacent levels through the same port. Once the spinal needle was docked on the inferior part of the superior lamina of the level to be decompressed first, the needle track was infiltrated with local anaesthetic (15 mL of normal saline and 5 mL 0.5% Bupivacaine) to provide pre-emptive analgesia. A vertical skin incision of 20 mm length centring over the entry point of the needle was scored along the paramedian line. The dissection was then carried deeper and the lumbar fascia incised. Tubular dilators (METRx System, Medtronic SofamorDanek, Memphis, TN) were inserted in the increasing order of diameters to dilate the muscular opening and a 18 mm diameter tube of appropriate length was docked over the inferior part of the superior lamina. C-arm was then used to verify the correct placement of the tube (
The authors timed the length of operation in minutes, from skin incision till the application of surgical dressing and calculated the blood loss in millilitres. The hospital stay was counted in days. All the patients completed a pre-operative Visual Analogue Scale (VAS) scale and ODI (Oswestry Disability Index) questionnaire and at post-operative day 1, 3 months, 6 months and 24 months and latest follow-up.
Statistical analysis was performed using SPSS (version 23, IBM Inc.). The Univariate analysis included tabulating frequencies for ordinal and categorical variables and calculating the standard deviation, ranges and means for the continuous variables. The ODI and VAS scores between pre-operative and post-operative day 1, 3 months, 6 months, 24 months and the latest follow-up were compared. Statistical significance was set at p<0.05 at 95% confidence interval.
Of the 502 patients of lumbar canal stenosis operated for TD, 68 (13.54%) satisfied the inclusion criteria. Five patients were lost to follow-up and study was completed on 63 patients. All the patients agreed to take part in the study and to fill in the patient-based clinical outcome questionnaires. The mean duration of follow-up was 30.4 months (6–40 months). The mean age was 63.4 years (50–88) with a standard deviation of 18.6 years. There were 37 males (59%) and 26 females (41%). The mean BMI of the patients was 28 kg/m2 (23.6–38.4 kg/m2) (
The VAS improved from mean 3 (2–5) to 2 (1–4) and 7 (4–9) to 2 (1–5) for back and leg pain, respectively; while the ODI improved from a mean 44.6 (32–68) to 20.2 (16–42). The improvement on modified VAS and ODI was statistically significant (p<0.05) when a comparison was made between pre-op scores and most recent follow-up score (
Two (3.17%) patients had dural tear with CSF leaks. Both the cases were diagnosed intra-operatively and the muscle and fascial layers as well as the skin were closed in a water-tight fashion. The mobilization protocol was similar to others without dural tears. One patient (1.6%) had persistent S1 dermatomal leg pain (index L3-4, L4-5 and L5-S1 decompression). He demonstrated radiographic evidence of persistent lateral recess stenosis at L5-S1 level and was re-operated with a tubular approach successfully. None of patients had any evidence of surgical site infections, medical complications or death.
Multilevel lumbar canal stenosis is not an uncommon situation. Conventional laminectomy necessitates a longer incision, a deeper dissection leaving behind a large dead-space, scarring of the paraspinal muscles and the possibility of spinal instability [
Obesity plays a significant factor in these cases. Obese patients benefit the most from this single-incision-multi-level minimal access decompression. On one hand obese patients tend to have problems like difficult exposure, retraction of tissues, increased dead-space leading to hematoma formation, need for a drain, infection, poor healing etc. in reference to conventional laminectomy. These issues can lead to significant morbidity and poor recovery. On the other hand, this technique of single-incision-multi-level minimal access decompression appears tailor-made for obese patients. The authors realised that tubular retractors are held better by the tamponade effect of surrounding soft-tissues in obese patients, compared to thin patients. Again, the need for the use of longer tubes (60 mm/70 mm) in obese patients (increased distance between entry point on the skin surface and the docking point over the lamina) that act as lever in achieving the desired tube trajectory (
All five three-level stenosis cases (L3-L4, L4-L5, L5-S1) operated in the study were obese (BMI>32) and their vertebral column was deep. All of these cases had a thick back. Hence, we coined the term “Posterior Obesity” in these cases with thick para-spinal musculature and subcutaneous fat.
The limitations to the study are the retrospective nature of the study and absence of a comparative matched cohort operated through multiple incisions or conventional laminectomy which could have increased the strength of the study.
The outcomes support the feasibility of performing TD through a single incision in cases of multilevel lumbar canal stenosis. This is probably the first paper in literature elaborating on the technical aspects and clinical results of performing a two-level or three-level TD through a single incision. Posterior obesity marked by increased distance between the skin surface and the lamina as shown in this study helps in getting a precise tube trajectory for multi-level decompression through the same skin incision.
No potential conflict of interest relevant to this article.
A 59-year-old male (case 12) with L4-5 stenosis and L5-S1 lateral recess stenosis as seen in the sagittal (A) and axial (B) MRI images. The fluoroscopy images demonstrate docking of the tubes at L4-L5 (C) and L5-S1 (D) levels through a single incision.
Representative figure showing over the top decompression.
A 75-year-old morbidly lady (case 27) with L3-L4, L4-L5 and L5-S1 stenosis: AP and lateral X-rays (A), MRI sagittal films (B), MRI axial films (C). Fluoroscopic sequential docking of the tube at all three levels (D) and post-operative scar measuring 18 mm (E). Patient lying comfortably in the bed on the evening of the surgery (F).
A 68-year-old male (case 41) - preoperative MRI sagittal and axial (A, C) and lateral radiograph showing tube trajectories (B). 6 months post-operative axial MRI and CT scan (D, E) showing adequate decompression. Post-operative single surgical scar (F).
Tube trajectory possible through the same skin incision (distance of skin from the ideal docking point - X is a hypothetical distance).
Ease of achieving an ideal tube trajectory if the distance between the skin and ideal docking point is increased to 2X.
Relative difficulty in achieving desired tube trajectory if distance of the skin to the ideal docking point is reduced to 0.75X.
Demographics and peri-operative parameters
Tubular decompression (TD) | |
---|---|
Demographics | |
Total number of cases | 63 |
Mean age (in years) | 63±10.3 (50–88) |
Sex (M/F) | 37 (59%)/26 (41%) |
BMI (kg/m2) | 28±3.9 (23.6–38.4) |
LCS levels | |
L2-L3 and L3-L4 | 4 (6.34%) |
L3-L4 and L4-L5 | 20 (31.7%) |
L4-L5 and L5-S1 | 31 (49.20%) |
L2-L3, L3-L4 and L4-L5 | 3 (4.76%) |
L3-L4, L4-L5 and L5-S1 | 5 (7.93%) |
Peri-operative parameters | |
Mean hospital stay (d) | |
Two-level | 2.5±0.6 (2–3) |
Three-level | 2.75±0.5 (2–3) |
Mean operating time (min) | |
Two-level | 123.5±15.6 (110–178) |
Three-level | 128±16.2 (112–148) |
Mean blood loss (mL) | |
Two-level | 106±18 (80–142) |
Three-level | 128±22 (108–156) |
Mean follow-up (mo) | 30.6 |
Pre-operative (Pre-op) and post-operative (Po) VAS and ODI parameters for two-level and three-level TD (significance set at p<0.05)
Patient outcome parameters | Levels | Pre-op | Po day 1 | Po 3 months | Po 6 months | Po 24 months |
---|---|---|---|---|---|---|
VAS (back) | Two-level | 2.9±1.5 (2–5) | 2.1±1 (1–4) (p<0.05) | 1.7±0.7 (1–4) (p<0.05) | 1.95±0.7 (1–3) (p<0.05) | 1.0±0.8 (1–4) (p<0.05) |
Three-level | 3.25±1.2 (2–6) | 2.5±1.3 (1–4) (p<0.05) | 2.5±1 (1–3) (p<0.05) | 2.5±1 (1–3) (p<0.05) | 2.2±1 (1–3) (p<0.05) | |
VAS (leg) | Two-level | 6.8±1.3 (4–9) | 2.2±1 (1–5) (p<0.05) | 1.9±0.8 (1–3) (p<0.05) | 1.85±0.8 (1–4) (p<0.05) | 1.6±0.67 (1–3) (p<0.05) |
Three-level | 7.5±1.7 (5–9) | 2±1.1 (1–3) (p<0.05) | 2±1.4 (1–4) (p<0.05) | 2.25±1 (1–3) (p<0.05) | 2±1 (1–3) (p<0.05) | |
ODI | Two-level | 44.8±9.42 (32–68) (p<0.05) | 20.4±5.86 (16–42) (p<0.05) | 18.5±2.6 (16–22) (p<0.05) | 18.6±1.95 (16–22) (p<0.05) | 19±2.93 (16–26) (p<0.05) |
Three-level | 43±3.4 (38–46) | 19±1.1 (18–20) (p<0.05) | 19±2.2 (16–22) (p<0.05) | 19±2 (18–22) (p<0.05) | 18.5±1.9 (16–20) (p<0.05) |