How Does Cage Lordosis Influence Postoperative Segmental Lordosis in Lumbar Interbody Fusion.

BACKGROUND: Consideration of sagittal alignment is an integral part of spinal fusion surgery correlating with superior outcomes. Segmental lordosis is an important contributor to sagittal alignment. This study assessed surgical factors influencing segmental lordosis in a 360° fusion model, including cage dimensions, anterior longitudinal ligament resection, facetectomy, and posterior compression. METHODS: Six L3-4 synthetic spinal motion segments were used in a repeated measures design. Each sample was sequentially instrumented with lateral cages of increasing height and angle. Lordosis was assessed from lateral radiographs of intact and each instrumented condition. The effect of anterior longitudinal ligament resection, posterior compression with pedicle screws, and bilateral facetectomy was additionally examined. RESULTS: A linear relationship between segmental lordosis and cage height was found. This effect was greater with the anterior longitudinal ligament divided. In cages of the same anterior height, increased intrinsic cage lordosis did not result in increased segmental lordosis; cages with no intrinsic lordosis resulted in the highest segmental lordosis. In examining this finding, it was shown that posterior cage height had a larger influence on segmental lordosis. Posterior compression with pedicle screws and bilateral facetectomy increased the segmental lordosis by a further 3.4° and 2.6°, respectively. CONCLUSIONS: Cage height was a key factor, with posterior compression further increasing lordosis. The finding that 0° cages results in the most segmental lordosis was an unexpected finding and highlights the importance of appropriate sizing on resulting lordosis. These findings are relevant to cage selection but require further study prior to applying to clinical practice and may influence future cage design.

Chiari malformation, cervical disc prolapse and syringomyelia--always think twice.

We present the case of a 36-year-old man with neck pain and parasthesia of both upper limbs. Magnetic resonance imaging demonstrated a cervical disc protrusion with spinal cord compression, a Chiari I malformation and cervical syringomyelia. On clinical grounds it was suspected that the cervical stenosis was the symptomatic pathology and an anterior cervical decompression was performed, followed by arthroplasty. Post-operative imaging demonstrated adequate canal decompression, preserved cervical mobility and near-complete resolution of the syrinx. Syringomyelia has a multitude of causes and synchronous pathology can occur. Cervical spondylosis is infrequently associated with syringomyelia. Chiari I malformations are increasingly incidentally detected and asymptomatic. This first report of arthroplasty for cervical spondylosis associated with syringomyelia adds to the growing body of experience with this new technology.

The Morel-Lavallée lesion in thoracolumbar spine trauma-two index cases.

The Morel-Lavallée lesion (MLL) is a closed degloving injury caused by traumatic separation of the subcutaneous tissue from the underlying fascia, without a break in the overlying skin. We present two cases that demonstrate a previously unrecognised association of the MLL with thoracolumbar spine fractures. The lesion is frequently missed, or its significance is overlooked, on initial evaluation. Awareness of this injury should allow tailored strategies to decrease the high risk of wound complications.

Operative steps in management of benign nerve sheath tumors.

Benign peripheral nerve sheath tumors include the neurofibroma, schwannoma, and their plexiform variants. Operative management begins with an assessment of the relative risks associated with surgery compared with observation. The risks of observation include the risk of malignancy, the progression of symptoms, risk of delayed surgery, and ongoing patient suffering. The risks of surgery include anesthetic problems, wound complications, and neurological injury. New neurological deficits have been reported to occur in approximately 10 to 15% of surgically treated cases. In general, surgery is recommended for symptomatic or progressive lesions. Although the surgical approach will vary depending on the location, type, and extent of tumor, adherence to certain principles will facilitate success. Adequate visualization and successful removal will be achieved with detailed anatomical knowledge, an adequate extensile exposure to visualize the proximal and distal tumor extent, circumferential dissection of the tumor, microsurgical dissection under appropriate magnification, and meticulous hemostasis throughout the procedure.

Interspinous process spacers versus traditional decompression for lumbar spinal stenosis: systematic review and meta-analysis.

BACKGROUND: Interspinous spacers are used in selected patients for the treatment of lumbar spinal stenosis. The uses of interspinous devices are still debated, with reports of significantly higher reoperation rates and unfavourable cost-effectiveness compared to traditional decompression techniques. METHODS: Six electronic databases were searched from their date of inception to December 2015. Relevant studies were identified using specific eligibility criteria and data was extracted and analyzed based on predefined primary and secondary endpoints. RESULTS: Eleven comparative studies were obtained for qualitative and quantitative assessment, data extraction and analysis. There was no significant difference in VAS back pain, leg pain or ODI scores for standalone interspinous process device (IPD) vs. bony decompression. However, standalone IPD was associated with lower surgical complications (4% vs. 8.7%, P=0.03) but higher long-term reoperation rates (23.7% vs. 8.5%, P<0.00001). IPD as an adjunct to decompression had comparable patient-reported scores, complications and reoperation rates to decompression alone. CONCLUSIONS: Current evidence indicates no superiority for mid- to long-term patient-reported outcomes for IPD compared with traditional bony decompression, with lesser surgical complications but at the risk of significantly higher reoperation rates and costs.

Biomechanical evaluation of a biomimetic spinal construct.

BACKGROUND: Laboratory spinal biomechanical tests using human cadaveric or animal spines have limitations in terms of disease transmission, high sample variability, decay and fatigue during extended testing protocols. Therefore, a synthetic biomimetic spine model may be an acceptable substitute. The goal of current study is to evaluate the properties of a synthetic biomimetic spine model; also to assess the mechanical performance of lateral plating following lateral interbody fusion. METHODS: Three L3/4 synthetic spinal motion segments were examined using a validated pure moment testing system. Moments (±7.5 Nm) were applied in flexion-extension (FE), lateral bending (LB) and axial rotation (AR) at 1Hz for total 10000 cycles in MTS Bionix. An additional test was performed 12 hours after 10000 cycles. A ±10 Nm cycle was also performed to allow provide comparison to the literature. For implantation evaluation, each model was tested in the 4 following conditions: 1) intact, 2) lateral cage alone, 3) lateral cage and plate 4) anterior cage and plate. Results were analysed using ANOVA with post-hoc Tukey's HSD test. RESULTS: Range of motion (ROM) exhibited logarithmic growth with cycle number (increases of 16%, 37.5% and 24.3% in AR, FE and LB respectively). No signification difference (p > 0.1) was detected between 4 cycles, 10000 cycles and 12 hour rest stages. All measured parameters were comparable to that of reported cadaveric values. The ROM for a lateral cage and plate construct was not significantly different to the anterior lumbar interbody construct for FE (p = 1.00), LB (p = 0.995) and AR (p = 0.837). CONCLUSIONS: Based on anatomical and biomechanical similarities, the synthetic spine tested here provides a reasonable model to represent the human lumbar spine. Repeated testing did not dramatically alter biomechanics which may allow non-destructive testing between many different procedures and devices without the worry of carry over effects. Small intra-specimen variability and lack of biohazard makes this an attractive alternative for in vitro spine biomechanical testing. It also proved an acceptable surrogate for biomechanical testing, confirming that a lateral lumbar interbody cage and plate construct reduces ROM to a similar degree as anterior lumbar interbody cage and plate constructs.