Barton L. Sachs

Complications associated with the technique of pedicle screw fixation. A selected survey of ABS members.

A limited survey analysis of 617 surgical cases in which pedicle screw implants were used was undertaken to ascertain the incidence and variety of associated complications. The different implant systems used included variable spinal plating (n = 249), Edwards (n = 143), and AO fixateur interne (n = 101). The most common intraoperative problem was unrecognized screw misplacement (5.2%). Fracturing of the pedicle during screw insertion and iatrogenic cerebrospinal fluid leak occurred in 4.2% of cases. The postoperative deep infection rate was 4.2%. Transient neuropraxia occurred in 2.4% of cases, and permanent nerve root injury occurred in 2.3% of cases. Previously unreported injury to nerve roots occurred late in the postoperative course in three cases. Screw breakage occurred in 2.9% of cases. All other complications had an incidence of less than 2%. The authors conclude that pedicle screw placement may be associated with significant intraoperative and postoperative complications. This information is of value to surgeons using pedicle implant systems as well as to their patients. Repeat surgery is associated with greater numbers of complications.

Results of the prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential fusion for the treatment of 1-level degenerative disc disease.

Study Design. A prospective, randomized, multicenter, Food and Drug Administration-regulated Investigational Device Exemption clinical trial. Objective. To evaluate the safety and effectiveness of the ProDisc®-L (Synthes Spine, West Chester, PA) lumbar total disc replacement compared to circumferential spinal fusion for the treatment of discogenic pain at 1 vertebral level between L3 and S1. Summary of Background Data. As part of the Investigational Device Exemption clinical trial, favorable single center results of lumbar total disc replacement with the ProDisc®-L have been reported previously. Methods. Two hundred eighty-six (286) patients were treated on protocol. Patients were evaluated before and after surgery, at 6 weeks, 3, 6, 12, 18, and 24 months. Evaluation at each visit included patient self-assessments, physical and neurologic examinations, and radiographic evaluation. Results. Safety of ProDisc®-L implantation was demonstrated with 0% major complications. At 24 months, 91.8% of investigational and 84.5% of control patients reported improvement in the Oswestry Low Back Pain Disability Questionnaire (Oswestry Disability Index [ODI]) from preoperative levels, and 77.2% of investigational and 64.8% of control patients met the ≥15% Oswestry Disability Index improvement criteria. Overall neurologic success in the investigational group was superior to the control group (91.2% investigational and 81.4% control; P = 0.0341). At 6 weeks and 3 months follow-up time points, the ProDisc®-L patients recorded SF-36 Health Survey scores significantly higher than the control group (P = 0.018, P = 0.0036, respectively). The visual analog scale pain assessment showed statistically significant improvement from preoperative levels regardless of treatment (P < 0.0001). Visual analog scale patient satisfaction at 24 months showed a statistically significant difference favoring investigational patients over the control group (P = 0.015). Radiographic range of motion was maintained within a normal functional range in 93.7% of investigational patients and averaged 7.7°. Conclusions. ProDisc®-L has been found to be safe and efficacious. In properly chosen patients, ProDisc®-L has been shown to be superior to circumferential fusion by multiple clinical criteria.

Dallas discogram description. A new classification of CT/discography in low-back disorders.

A new classification method for CT/discography was developed. The Dallas discogram description (DDD) related five separate categories of information. Degeneration and annular disruption were regarded as separate phenomena. Additionally, provoked pain response, contrast volume, and miscellaneous information were recorded. Discogram findings of 59 patients with low-back and/or leg pain were graded according to the new method and compared with standard methods using routine anteroposterior and lateral discographic images. Findings from routine discogra-phy and CT/discography were graded and correlated with myelographic and plain computerized axial tomography (CAT) scans. This study demonstrated that the contrast-enhanced axial view provided by CT/discography served as a useful projection for demonstrating disc pathology. CT/discography analyzed according to DDD offered a more sensitive discriminator of disc degeneration from annular disruption (disc protrusion/leaking). This evaluation can be recommended as the procedure of choice when revision of spine surgery is considered or when there is an equivocal or negative correlation between clinical information and myelography or CAT scan.

Reported pain during lumbar discography as a function of anular ruptures and disc degeneration : a re-analysis of 833 discograms

Study Design This re-analysis was based on 833 computed tomography/discograms collected from 306 candidates for back surgery. Objectives The goal was to test the hypothesis that outer anular ruptures are the main determinant of the pain of discography. Summary of Background Data Previous analyses indicated univeriate associations of pain with disc degeneration and anular ruptures. Methods If present, pain was classified as “exact”, “similar”, or “dissimilar” reporduction of the previously experienced pain. For each disc, ruptures and degeneration were separately evaluated by a four-point scale. Multiple logistic regression with random effects was used in the analysis. Results Outer anular ruptures were the only predictor of the responses “similar” and “exact”. General disc degeneration was the only predictor of the response “dissimilar”. There was no effect modification due to gender, age, and spinal level. Conclusions During discography, the outer anulus appears to be the origin of pain reproduction.

Lumbar spine arthroplasty: early results using the ProDisc II: a prospective randomized trial of arthroplasty versus fusion.

This study represents the first 39 patients with at least 6-month follow-up enrolled in a prospective randomized Food and Drug Administration study evaluating the safety and efficacy of the ProDisc II versus the control, a 360° lumbar spinal fusion. Data were collected preoperatively and at 6 weeks, 3 months, and 6 months postoperatively. Visual Analog Scale (VAS), Oswestry Low Back Pain Disability Questionnaire (ODQ), and patient satisfaction rates were evaluated at these intervals, as well as range of motion, return to work, and recreational and ambulatory status. There were 28 ProDisc patients and 11 who underwent fusion. Six patients had two-level surgery. Estimated blood loss (ProDisc = 69 mL versus fusion = 175 mL) and operative time (ProDisc = 75 minutes versus fusion = 219 minutes) were significantly different (P < 0.01). Hospital stays were shorter (ProDisc = 2.1 days versus fusion = 3.5 days [P < 0.01]) for ProDisc patients. There was a significantly greater reduction in the ODQ scores at 3 months in the ProDisc group compared with the fusion group (P < 0.05). No difference was noted in VAS. A trend was identified at 6 months in patient satisfaction rates favoring ProDisc versus fusion (P = 0.08), and motion was significantly improved in ProDisc patients compared with the fusion group (P = 0.02). Ambulatory status as well as recreational activity improved faster in the ProDisc group. The data suggest that total disc arthroplasty may be an attractive option as opposed to lumbar fusion for the surgical treatment of disabling mechanical low back pain secondary to lumbar disc disease.

The relationship of pain provocation to lumbar disc deterioration as seen by CT/discography

The CT/discographic findings from 225 discs in 91 low-back pain patients were compared to the pain provocation during the injection of contrast into the disc. The radio-graphic appearance of disc deterioration demonstrating disc degeneration and annular disruption of each disc was classified separately using a fourpoint scale: normal, slight, moderate, or severe. Pain reaction to the discogram at each level was recorded as follows: no pain, dissimilar pain, similar pain, or exact reproduction of the patients clinical pain. This more precise analysis demonstrated a significant relationship between pain and deterioration of discs. The CT/discogram presents an axial view of the disc that allows a subgrouping of disc deterioration that can discriminate between peripheral deterioration (degeneration) and internal deterioration (disruption). The disruption supposedly occurs earlier and is more likely to be the source of exact pain reproduction.

In vitro simulation : Early results of stereotaxy for pedicle screw placement

Study Design. Frameless stereotaxy with doppler ultrasound and three dimensional computer model registration is assessed in vitro for pedicle screw placement. Objective. To identify feasibility of pedicle screw navigation and placement using this technology. Summary of Background Data. Inaccurate pedicle screw placement can lead to neurovascular injury or suboptimal fixation. Present techniques in pedicle screw placement involve only confirmation of hole orientation. Method. Forty‐four pedicle screws were placed in lumbosacral models and cadaver specimens. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning. Results. All screws were intrapedicular. Accuracy of anterior cortical fixation was 1.5 mm, with a range of 2.5 mm. Conclusion. In vitro frameless stereotaxy is accurate for pedicle screw placement. This technology adds a component of navigation to pedicle screw placement.

Disc deterioration in low-back syndromes: a prospective, multi-center CT/discography study

Disc deterioration and pain provocation in different low-back pain syndromes was studied using computed tomography (CT) discography. Data were prospectively collected for 300 patients (816 discs). Patients were classified by their pre-discography diagnosis of disc herniation (DH), degenerated disc (DD), lumbar syndrome (LS), lumbar radicular syndrome (LRS), or other. The CT/discograms were classified by discographic pain response, the amount of degeneration and annular disruption. Eighty-two percent of DH patients, 80% of DD, 56% of LS, and 59% of LRS patients had both positive discographic pain provocation and moderate or severe disc deterioation. The study indicates that intradiscal pathology plays a major role in nonspecific low-back pain syndromes.

Anterolateral dynamized instrumentation and fusion for unstable thoracolumbar and lumbar burst fractures.

Study Design. A retrospective chart review of 36 patients treated with dynamized anterolateral instrumentation and fusion after decompression for thoracolumbar and lumbar burst fractures is presented. Objectives. To evaluate a device that allows continual bone graft vertebral endplate compression and determine its potential for healing in patients with thoracolumbar and lumbar burst fractures. Summary of Background Data. Anterior spinal surgery has led to implant adaptations. Such implants have undergone an evolution in hopes of improving the rate of healing and avoiding neurovascular catastrophes. Methods. Thirty‐six patients underwent anterior decompression dynamized instrumentation and fusion for thoracolumbar and lumbar burst fractures. This involved a dual‐rod, quadrilateral, cross‐linked frame that allows for continual compression but deters rotation and shear stresses. Results. All patients healed solidly without instrumentation failure. An average recovery of 1.3 Frankel grades was recorded. Subsidence of bone graft vertebral endplate was less than in those placed in a trough. Conclusions. Dynamized load‐sharing anterolateral Cotrel‐Dubousset instrumentation led to solid bone graft healing without implant failure by allowing continual compression while deterring shear and rotational stresses.

Recombinant activated factor VII in spinal surgery: a multicenter, randomized, double-blind, placebo-controlled, dose-escalation trial.

Study Design. Randomized, placebo-controlled, double-blind, multicenter, Phase IIa study. Objective. To assess the safety and efficacy of recombinant-activated Factor VII (rFVIIa) in major spinal surgery. Summary of Background. Spinal fusion surgery can cause substantial blood loss and blood product transfusions. Recombinant FVIIa is approved for treatment of bleeding in patients with coagulation abnormalities and has been shown to reduce blood loss and transfusion requirements in surgery in patients with no underlying coagulopathy. Methods. Forty-nine patients undergoing fusion of 3 or more vertebral segments were randomized and treated on losing 10% of their estimated blood volume (with total expected surgical blood loss ≥ 20%) and received 3 doses (2-hour intervals) of placebo (n = 13) or 30, 60, or 120 &mgr;g/kg rFVIIa (n = 12 per group). The primary endpoint was safety. A priori-defined efficacy endpoints included blood loss and transfusion requirements between placebo and each rFVIIa dose group, adjusted for surgery duration, number of segments fused, and estimated blood volume. Results. Serious adverse events did not occur at any greater frequency in any of the treatment groups. One patient (3 × 30 &mgr;g/kg rFVIIa) with advanced cerebrovascular disease (undiagnosed, trial exclusion criterion) died 6 days after surgery due to an ischemic stroke. Mean blood loss was as follows: 2270 mL for placebo; 1909, 1262, and 1868 mL for 3 × 30, 3 × 60, and 3 × 120 &mgr;g/kg rFVIIa, respectively (differences not statistically significant). Mean adjusted surgical blood loss was as follows: 2536 mL for placebo; 1120, 400, and 823 mL for 3 × 30, 3 × 60, and 3 × 120 &mgr;g/kg rFVIIa, respectively (P ≤ 0.001). Mean surgical transfusion volume was reduced by 27% to 50% with rFVIIa treatment (not significant). The mean adjusted surgical transfusion volume was reduced by 81% to 95% with rFVIIa treatment (P ≤ 0.002). Conclusion. No safety concerns were indicated for the use of rFVIIa in patients at all doses tested; rFVIIa reduced adjusted blood loss and adjusted transfusions during spinal surgery.