Vertebral column

Endoscope-assisted sp.inal decompression surgery for lumbar spinal stenosis

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Abstract

OBJECT

The authors undertook this study to document the clinical outcomes of microendoscopic laminotomy, a minimally invasive decompressive surgical technique using spinal endoscopy for lumbar decompression, in patients with lumbar spinal stenosis (LSS).

METHODS

A total of 366 patients were enrolled in the study and underwent microendoscopic laminotomy between 2007 and 2010. Indications for surgery were single- or double-level LSS, persistent neurological symptoms, and failure of conservative treatment. Microendoscopy provided wide visualization through oblique lenses and allowed bilateral decompression via a unilateral approach, through partial resection of the base of the spinous process, thereby preserving the supraspinous and interspinous ligaments and contralateral musculature. Clinical symptoms and signs of low-back pain were evaluated prior to and following surgical intervention by applying the Japanese Orthopaedic Association (JOA) scoring system, Roland-Morris Disability Questionnaire (RMDQ), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and 36-Item Short Form Health Survey (SF-36). These items were evaluated preoperatively and 2 years postoperatively.

RESULTS

Effective circumferential decompression was achieved in all patients. The 2-year follow-up evaluation was completed for 310 patients (148 men and 162 women; mean age 68.7 years). The average recovery rate based on the JOA score was 61.3%. The overall results were excellent in 34.9% of the patients, good in 34.9%, fair in 21.7%, and poor in 8.5%. The mean RMDQ score significantly improved from 11.3 to 4.8 (p < 0.001). In all categories of both JOABPEQ and SF-36, scores at 2 years’ follow-up were significantly higher than those obtained before surgery (p < 0.001). Twelve surgery-related complications were identified: dural tear (6 cases [1.9%]), wrong-level operation (1 [0.3%]), transient neuralgia (4 [1.3%]), and infection (1 [0.3%]). All patients recovered, and there were no serious postoperative complications.

CONCLUSIONS

Microendoscopic laminotomy is a safe and very effective minimally invasive surgical technique for the treatment of degenerative LSS.

Source: JNS.

A novel device to simplify intraoperative radiographic visualization of the cervical spine by producing transient caudal shoulder displacement

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Abstract

OBJECT

Intraoperative radiographic localization within the cervical spine can be a challenge because of the anatomical relation of the musculoskeletal structures of the pectoral girdle. On standard cross-table lateral radiographs, these structures can produce shadowing that obscure the anatomical features of the cervical vertebrae, particularly at the caudal levels. Surgical guidelines recommend accurate intraoperative localization as a means to reduce wrong-level spine surgery, and unobstructed visualization is needed for fluoroscopy-guided placement of spinal instrumentation. In this article, the authors describe and evaluate a novel device designed to provide transient intraoperative caudal displacement of the shoulders to improve and simplify radiographic visualization of the cervical spine.

METHODS

A 2-center prospective study was conducted to evaluate the device. The study included a total of 80 patients undergoing cervical spine surgery. The device was evaluated in a cohort of 50 patients undergoing elective single-level anterior discectomy and fusion and also in a second cohort of 30 patients at an independent institution. The patients in this second cohort were undergoing a variety of cervical spine procedures for multiple indications and were included in the study to allow the authors to assess the effectiveness of the device in a general neurosurgical practice. After the patients were anesthetized and positioned, consecutive standard cross-table lateral radiographs or intraoperative fluoroscopic were obtained before and after use of the device. The images were compared in order to determine the difference in lowest vertebral level visible.

RESULTS

There was an average difference in cervical spine visualization of +2.8 ± 0.9 vertebral levels in the first cohort, while in the second the improvement was +1.2 ± 0.7 levels (p < 0.0001 between cohorts, unpaired t-test). There was one complication, a minor shoulder abrasion, which required no specific management.

CONCLUSIONS

This device is safe and effective for increasing the radiographic visualization of the cervical spine for intraoperative localization.

Source: JNS.

The effect of screw head design on rod derotation in the correction of thoracolumbar spinal deformity.

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Abstract

OBJECT

The use of fixed-axis pedicle screws for correction of thoracolumbar deformity in adult surgery is demanding because of the challenge of assembling the bent rod to the screw in order to achieve curve correction. Polyaxial screw designs, providing increased degrees of freedom at the screw-rod interface, were reported to be insufficient in achieving correction of thoracic deformity in the axial plane. Using a multisegment bovine calf spine model, this study investigated the ability of a new uniplanar screw design to achieve derotation correction of the vertebrae and maintain a degree of correction comparable to that of fixed-axis and polyaxial screw designs.

METHODS

Eighteen calf thoracolumbar spine segments from T-6 to L-1 (n = 6 per screw design) underwent bilateral facetectomies at the T9–11 levels and were instrumented bilaterally with pedicle screws and rods. To assess the efficacy of each screw design in imparting rotational correction, each instrumented level was tested under applied torsional moments designed to simulate the motion applied during derotation surgery. Once rotation was achieved, the whole spine was tested to assess the overall stiffness of the construct.

RESULTS

The fixed-axis construct showed increased efficacy in imparting rotation compared with the uniplanar (115% increase, p > 0.05) and polyaxial (210% increase, p < 0.05) constructs. Uniplanar screws showed a 21% increase in torsional stiffness compared with the polyaxial screws, but this difference was not statistically significant.

CONCLUSIONS

The design of screw heads plays a significant role in affecting the rotation of the vertebrae during the derotation procedure. Uniplanar screws may have the advantage of maintaining construct stiffness after derotation.

Source: http://thejns.org

Once-Yearly Zoledronic Acid for Men with Osteoporosis.

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This drug lowered the incidence of radiographic, but not clinical, vertebral fractures.

In a 2007 study, once-yearly infusions of the bisphosphonate drug zoledronic acid (Reclast, Aclasta) lowered the incidence of fractures in postmenopausal women (JW Gen Med May 2 2007). Now, in another industry-sponsored randomized trial, 1199 men (age range, 50–85) at high risk for fractures received zoledronic acid (5-mg dose, given intravenously at baseline and at 12 months) or placebo. The study was open to men with osteoporosis defined by bone-density testing and to men with osteopenia plus one to three mild-to-moderate vertebral fractures identified by lateral spine radiographs.

At 2 years, the proportion of men with new radiographic vertebral fractures was significantly lower in the zoledronic acid group than in the placebo group (1.6% vs. 4.9%). A small difference in incidence of symptomatic vertebral or nonvertebral fractures (1.0% vs. 1.8%) did not reach significance. About 20% to 25% of zoledronic acid recipients developed fever, myalgia, or arthralgia (compared with about 5%–10% of placebo recipients), but the duration of these adverse effects was not reported. No cases of jaw osteonecrosis or atypical femoral fractures were noted, but myocardial infarction occurred in nine zoledronic acid recipients and in two placebo recipients (P=0.03).

Comment: A once-yearly infusion of zoledronic acid significantly lowered the incidence of radiographic vertebral fractures, but not clinical fractures, in this 2-year study in men. Infusions of this drug are known to cause transient flu-like symptoms; however, the small excess of myocardial infarctions was unexpected and is of some concern. In the trial in women that was cited above, zoledronic acid recipients experienced a higher incidence of serious atrial fibrillation (but not myocardial infarctions).

Source: Journal Watch General Medicine