[Minimally invasive spine arthrodesis in degenerative spinal disorders]

Transversus Abdominis Plane Block for Anterior Lumbar Interbody Fusion: a randomized controlled trial

BACKGROUND CONTEXT

ALIF (Anterior Lumbar Interbody Fusion) is a lumbar arthrodesis technique via an anterior approach that is less invasive than the posterior approaches. However, it is associated with specific pain in the abdominal wall.

PURPOSE

The objective of this study was to determine whether performing a bilateral ultrasound-guided TAP (Transversus Abdominis Plane) block allows a reduction in morphine consumption in the first 24 hours after surgery.

STUDY DESIGN

This study is a prospective single-centre, randomized, double-blind study.

PATIENT SAMPLE

Patients undergoing ALIF surgery were included and randomized into two groups. Both groups received a TAP block performed at the end of surgery with either ropivacaine or placebo.

OUTCOME MEASURES

The primary outcome measure was morphine consumption in the first 24 hours. The main secondary outcomes were immediate postoperative pain and opioid-related side effects METHODS: Intra- and postoperative anaesthesia and analgesia protocols where standardized. A bilateral ultrasound-guided TAP block was performed with 75 mg (in 15 ml) of ropivacaine per side or isotonic saline serum depending on their assignment group.

RESULTS

Forty-two patients were included in the study (21 per group). Morphine consumption at 24 hours (28 mg [18 - 35] in the ropivacaine group vs 25 mg [19 - 37] in the placebo group (p=0.503)) were not significantly different between the 2 groups.

CONCLUSION

TAP block with ropivacaine or placebo provided a similar postoperative analgesia when associated with a multimodal analgesia protocol for ALIF.

Biomechanical investigation of a minimally invasive posterior spine stabilization system in comparison to the Universal Spinal System (USS)

Background

Although minimally invasive posterior spine implant systems have been introduced, clinical studies reported on reduced quality of spinal column realignment due to correction loss. The aim of this study was to compare biomechanically two minimally invasive spine stabilization systems versus the Universal Spine Stabilization system (USS).

Methods

Three groups with 5 specimens each and 2 foam bars per specimen were instrumented with USS (Group 1) or a minimally invasive posterior spine stabilization system with either polyaxial (Group 2) or monoaxial (Group 3) screws.

Mechanical testing was performed under quasi-static ramp loading in axial compression and torsion, followed by destructive cyclic loading run under axial compression at constant amplitude and then with progressively increasing amplitude until construct failure.

Bending construct stiffness, torsional stiffness and cycles to failure were investigated.

Results

Initial bending stiffness was highest in Group 3, followed by Group 2 and Group 1, without any significant differences between the groups.

A significant increase in bending stiffness after 20’000 cycles was observed in Group 1 (p = 0.002) and Group 2 (p = 0.001), but not in Group 3, though the secondary bending stiffness showed no significant differences between the groups.

Initial and secondary torsional stiffness was highest in Group 1, followed by Group 3 and Group 2, with significant differences between all groups (p ≤ 0.047). A significant increase in initial torsional stiffness after 20’000 cycles was observed in Group 2 (p = 0.017) and 3 (p = 0.013), but not in Group 1.

The highest number of cycles to failure was detected in Group 1, followed by Group 3 and Group 2. This parameter was significantly different between Group 1 and Group 2 (p = 0.001), between Group 2 and Group 3 (p = 0.002), but not between Group 1 and Group 3.

Conclusions

These findings quantify the correction loss for minimally invasive spine implant systems and imply that unstable spine fractures might benefit from stabilization with conventional implants like the USS.

Radiological and clinical outcomes following extreme lateral interbody fusion

Object

Extreme lateral interbody fusion (ELIF) is a popular technique for anterior fixation of the thoracolumbar spine. Clinical and radiological outcome studies are required to assess safety and efficacy. The aim of this study was to describe the functional and radiological impact of ELIF in a degenerative disc disease population with a longer follow-up and to assess the durability of this procedure.

Methods

Demographic and perioperative data for all patients who had undergone ELIF for degenerative lumbar disorders between 2007 and 2011 were collected. Trauma and tumor cases were excluded. For radiological outcome, the preoperative, immediate postoperative, and latest follow-up coronal Cobb angle, lumbar sagittal lordosis, bilateral foraminal heights, and disc heights were measured. Pelvic incidence (PI) and PI–lumbar lordosis (PI-LL) mismatch were assessed in scoliotic patients. Clinical outcome was evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS), as well as the Macnab criteria.

Results

One hundred forty-five vertebral levels were surgically treated in 90 patients. Pedicle screw and rod constructs and lateral plates were used to stabilize fixation in 77% and 13% of cases, respectively. Ten percent of cases involved stand-alone cages. At an average radiological follow-up of 12.6 months, the coronal Cobb angle was 10.6° compared with 23.8° preoperatively (p < 0.0001). Lumbar sagittal lordosis increased by 5.3° postoperatively (p < 0.0001) and by 2.9° at the latest follow-up (p = 0.014). Foraminal height and disc height increased by 4 mm (p < 0.0001) and 3.3 mm (p < 0.0001), respectively, immediately after surgery and remained significantly improved at the last follow-up. Separate evaluation of scoliotic patients showed no statistically significant improvement in PI and PI-LL mismatch either immediately postoperatively or at the latest follow-up. Clinical evaluation at an average follow-up of 17.6 months revealed an improvement in the ODI and the VAS scores for back, buttock, and leg pain by 21.1% and 3.7, 3.6, and 3.7 points, respectively (p < 0.0001). According to the Macnab criteria, 84.8% of patients had an excellent, good, or fair functional outcome. New postoperative thigh numbness and weakness was detected in 4.4% and 2.2% of the patients, respectively, which resolved within the first 3 months after surgery in all but 1 case.

Conclusions

This study provides what is to the authors' knowledge the most comprehensive set of radiological and clinical outcomes of ELIF in a fairly large population at a midterm follow-up. Extreme lateral interbody fusion showed good clinical outcomes with a low complication rate. The procedure allows for at least midterm clinically effective restoration of disc and foraminal heights. Improvement in coronal deformity and a small but significant increase in sagittal lordosis were observed. Nonetheless, no significant improvement in the PI-LL mismatch was achieved in scoliotic patients.

Perioperative morbidity and complications in minimal access surgery techniques in obese patients with degenerative lumbar disease

The medical profession is increasingly confronted with the epidemic phenomenon of obesity. Its impact on spine surgery is not quite clear. Published data concerning the use of minimally invasive surgery (MIS) in the spine among obese patients is scarce. The purpose of the present retrospective study was to evaluate perioperative as well as postoperative complication rates in MIS fusion of the lumbar spine in obese, overweight and normal patients classified according to their body mass index. Lumbar MIS fusion was performed by means of TLIF procedures and/or posterolateral fusion alone. A laminotomy was performed in patients with spinal stenosis. Of 72 patients, 39 underwent additional laminotomy for spinal stenosis. No differences were registered in respect of the numbers of fused segments or cages. Any harmful event occurring peri- or postoperatively was noted and included in the statistical analysis. No infection at the site of surgery or severe wound healing disorder was encountered. We registered no difference in blood loss, drainage, or the length of the hospital stay between the three BMI groups. We also observed no difference in complication rates between the three groups. This study confirms the low soft tissue damage of minimal access surgery techniques, which is an important type of surgery in obese patients. The smaller approach helps to minimize infections and wound healing disorders. Moreover, deeper regions of wounds are clearly visualized with the aid of tubular retractors.