The "slide technique": an improvement on the "funnel technique" for safe pedicle screw placement in the thoracic spine.

STUDY DESIGN: Technical note. OBJECTIVES: To report and describe a new free-hand technique for pedicle screw placement in the thoracic spine especially in severe deformities. Because of distortion of anatomic landmarks scoliosis, this free-hand placement technique based on pedicle access through the decancelled transverse process is a safe procedure. METHODS: Transverse process is widely exposed and its posterior cortex is decorticated. The cancellous bone content of the transverse process is completely removed using a small curette. Bone wax is applied to avoid local bleeding and then the decancelled transverse process is inspected. The entry of the pedicle is then easily identified by the presence of remaining cancellous bone. A pedicular probe is then inserted and gently advanced. During pedicle probe insertion, the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle act as a "slide" to permit safe insertion of the instrument. RESULTS: In our experience, no patient required additional procedures for screw revision, and no neurologic deficit occurred stemming from malpositioning of pedicle screws. The key point of the "slide technique" is to use the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle as a "slide" to permit correct probe positioning during pedicle probe insertion. CONCLUSIONS: This technique is very close to the "funnel technique". The "funnel" and then the "slide" technique are mostly useful in complex spinal deformities as in neuromuscular patients. The "slide technique" is a safe, effective and cost-effective technique for pedicle screw placement in the thoracic spine especially in severe deformities. LEVEL OF EVIDENCE: IV.

"Bone-οn-Bone" surgical reconstruction of moderate severity, flexible single curve adolescent idiopathic scoliosis: continuing improvements of the technique and results in three scoliosis centers after almost twenty years of use.

The "bone-on-bone" reconstruction for adolescent idiopathic scoliosis is reviewed in this article. Extensive use over the past 18 years has identified it's functional benefits outstanding clinical results, and very limited complications. This is an extensive update of it's application, since it's introduction, 18 years ago.

Repetitive vs. single transcranial electrical stimulation for intraoperative monitoring of motor conduction in spine surgery.

We studied the effectiveness of single and repetitive transcranial electrical stimulation to activate motor tracts under partial neuromuscular blockade and total intravenous anesthesia. During spinal surgery, in 10 patients, the latency and amplitude of the evoked abductor pollicis brevis muscle response after cortical stimulation was calculated and compared. The number of responses evoked by the double (pair) pulse stimulation was significantly higher (p = 0.0191) than single pulse stimulation. Repetitive stimulation caused more responses than single (p = 0.0001) or double stimulation (p = 0.0253). An increase of interstimulus interval from 1-3 msec did not significantly increase the motor response with the double pulse or repetitive stimulations. Varying the number of electrical pulses per train stimulation from 3-9 did not significantly change latency (P > 0.05) or amplitude (P > 0.05) of the motor response. The findings suggest that use of repetitive stimulation of the motor cortex is an effective method to activate motor pathway during spinal surgery.

Short segment bone-on-bone instrumentation for adolescent idiopathic scoliosis: a mean follow-up of six years.

STUDY DESIGN: Prospective case series. OBJECTIVE: To evaluate the clinical and radiologic outcomes of short segment anterior scoliosis surgery with bone-on-bone apposition using a dual screw, dual rod system. SUMMARY OF BACKGROUND DATA: Posterior segmental fixation for correction of AIS involves instrumentation of all the vertebrae included in the major curve. Our short segment anterior technique produces similar results by fusion of fewer levels. METHODS: Forty-five patients operated between 1996 and 2004. Twenty-eight thoracic (Lenke 1) and 17 thoracolumbar (Lenke 5). The mean age was 19 years, 87% were females, and the mean follow-up was 72 months (range 28-121 months). We operated on curves less than 85° with "total discectomy," bone-on-bone apposition, and dual-screw, dual-rod fixation. RESULTS: A mean of five vertebrae (four discs) were instrumented, with a mean operative time of 360 minutes, blood loss of 877 mL and a hospital stay of 9.1 day. Lenke 1. The main preop thoracic curve was 52.5°, final postop curve 27.9°, by fusing five vertebrae, four discs. A spontaneous improvement of 47.5% of the lumbar compensatory curve was seen. The lower tilt angle corrected from 20.9° to 11°. Lenke 5. The preoperative thoracolumbar major curve corrected from 50.5° to 18.3° (final) with fusion of four vertebrae, three discs. A spontaneous improvement of 37.4% occurred in the thoracic compensatory curve. The preop tilt angle improved from 27.7° to 8.3°.The sagittal and coronal balance was restored in all the patients. There were no neurologic, vascular, pulmonary, or implant-related complications. Union occurred within 3 months. All the patients returned to an unrestricted lifestyle within 4 months. CONCLUSION: We report good results after surgical correction using our short segment bone-on-bone technique. Improvements were noted and maintained, over a 6-year period.

L5 vertebrectomy for the surgical treatment of spondyloptosis: thirty cases in 25 years.

STUDY DESIGN: Retrospective review. OBJECTIVES: To review the long-term results, complications, and predictability of outcomes of the L5 vertebrectomy and reduction of L4 onto S1 for the surgical treatment of fixed spondyloptosis. SUMMARY OF BACKGROUND DATA: Before the development of the procedure, surgical instrumentation with Harrington rods and posterolateral fusion, or fusion in situ with cast immobilization, with or without a period of bedrest, in the cast, were the alternatives for patients who elected operative treatment. METHODS: Charts, operative notes, hospital and office records, preoperative and postoperative radiographic studies, and clinical photographs were reviewed for the 30 patients who had had the L5 vertebrectomy, over the past 25 years. The average follow-up of the patients was 15 years. The follow-up was performed by the treating physician/surgeon. RESULTS: The clinical results of the first 16 patients were independently reviewed by a surgeon who was not involved in the patients treatment, at all. His independent review indicated that the patients were functioning well. All of them would recommend the surgery to other patients who needed it. None of them was taking narcotic medication on a regular basis. The follow-up of the additional 14 patients operated since that review was performed by the author. The results of the patients operated since 1994 was the same as the group operated before 1994, except there have been 2 patients who had to have surgical revision and reinstrumentation for screw fracture, although neither lost reduction, as a consequence of their nonunion and screw fracture. Both healed their reconstruction, following removal and replacement of the fractured pedicle screws and grafting of the nonunion. None of the patients has required any treatment at all (surgical or nonsurgical) for "junctional problems" with follow-up, now, on the earliest patients, up to 25 years. Improvement in the "spinal performance" of the patients, in particular the resolution of the "crouch gait," which many of them showed before surgery, is particularly gratifying to them, since, for that group, the improvement in gait efficiency is particularly dramatic. CONCLUSIONS: Extensive review of all the complications in the series is accomplished in the manuscript. While 23 of the patients have had some temporary clinical deficit in the L5 root for from 6 weeks to 3 years following their reconstruction, all but 2 have recovered fully, and only 2 of the patients wear ankle foot orthoses (AFO) on a regular basis. No patient has had any problem with bowel or bladder or sexual neurologic deficit, but 1 patient does have retrograde ejaculation.

Abnormal spinal anatomy in 27 cases of surgically corrected spondyloptosis: proximal sacral endplate damage as a possible cause of spondyloptosis.

STUDY DESIGN: Retrospective review. OBJECTIVES: To review the findings in the cases of spondyloptosis we have treated and to postulate on the possible cause of spondyloptosis. SUMMARY OF BACKGROUND DATA: Spondyloptosis (Grade V spondylolisthesis) is rare, even though spondylolisthesis is a relatively common condition. While it is known that progression to spondyloptosis occurs in patients with developmental spondylolisthesis in their childhood and/or adolescent years, the precise factors leading to progression are not known. METHODS: Between 1979 and 2002, 27 patients with spondyloptosis were treated surgically with L5 resection and reduction of L4 onto S1. During the treatment process, detailed observations of the surgical findings were made through clinical and radiologic means. Six anatomic parameters (pars interarticularis defects, spina bifida of the L5 or sacral segments, dysplasia of the L5-S1 facet joints, L5-S1 disc degeneration, trapezoidal shape of L5, and rounding of the proximal end of the sacrum) were specifically studied. RESULTS: Pars interarticularis defects were present in 24 patients (88.9%), facet dysplasia in 16 patients (59.2%), spina bifida in 24 patients (88.9%), disc degeneration in 25 (92.6%), trapezoidal L5 in 20 patients (74.1%), and rounding of the proximal end of S1 in all 27 patients (100%). CONCLUSIONS: Rounding of the proximal sacral endplate was the only constant abnormal anatomic feature in the patients. Damage to the proximal sacrum and sacral growth plate during late childhood and early adolescence, similar to the epiphyseal injury that produces Blount's disease, and slipped capital femoral epiphysis seem to be key factors permitting the progression of developmental spondylolisthesis to spondyloptosis.

The accuracy of pedicle screw placement in the thoracic spine using the "Funnel Technique": part 1. A cadaveric study.

A cadaveric study using the "funnel technique" to probe thoracic pedicles was conducted. The results (location, level, and perforation rate) of three spine surgeons of varying experience were compared. The objectives were to evaluate the reliability and accuracy of the funnel technique for the placement of thoracic pedicle screws and to describe the technique. Nine fresh cadavers (216 thoracic pedicles) were used for pedicle screw placement using the funnel technique. The study was conducted by three spine surgeons with a significantly different level of experience in thoracic pedicle screw placement (72 thoracic pedicles each). Critical and noncritical perforations were recorded. The perforation rate was 6% (13 of 216 pedicles). Of this, only 0.4% (1 of 216) was a critical perforation (a contact with T8 nerve root). The junior spine surgeon who had no previous experience with thoracic pedicle screw placement had a 12.5% (9 of 72) perforation rate, the surgeon very familiar with the technique had a 5.5% (4 of 72) perforation rate, and the senior author who originated this technique had a 1.4% (1 of 70) perforation rate. All perforations made by the junior spine surgeon occurred in his first 24 pedicles; none occurred in his last 48 pedicles. The reliability of the funnel technique in placement of thoracic pedicle screws was proven in our cadaveric study. It provided even an entry-level surgeon with a safe way to identify and place thoracic pedicle screws. The funnel technique is a simple, safe, and cost-effective alternative to any other currently recommended techniques for pedicle screw placement.

Possible complications of anterior perforation of the vertebral body using cervical pedicle screws.

No previous studies have analyzed the possible complications of anterior perforation of the cervical vertebral body with pedicle screws. The objective of this study was to identify the possible implications of an anterior vertebral body perforation. Ten consecutive Euro-American cadavers (C2-C7) were used. The male-to-female ratio was 3:7. The average specimen age was 79.6 years (range: 65-97 years), and average height was 159 cm (range: 155-175 cm). Axial computed tomography scans through the isthmus of pedicles were taken. Five millimeter and 10 mm margins anterior to the vertebral bodies were defined. Within 5 mm anterior to the anterior cortex of the vertebral body, we found mostly muscles (at C2: m. longus colli and pharyngeal constrictors; at C3 and C4: m. scalenus medius, longus colli, pharyngopalatinus and pharyngeal constrictors; at C5 and C6: m. longus colli and longus capitis; and at C7: m. longus colli), except at C3, C4, and C7, where the pharynx and esophagus were within the margin. Between 6 and 10 mm, we found mostly hollow organs (at C2: pharynx and small veins; at C3 and C4: the same muscles as within the 5 mm margin, with addition of the pharynx and some small veins; at C5 and C6: pharynx, pharyngeal constrictors and the thyroid cartilage; and at C7: the esophagus). Except C2, there is no safe zone anterior to the cervical vertebral bodies in the cervical spine, which would allow bicortical purchase of pedicle screws without being close to important surrounding structures.

Thoracic pedicle screw instrumentation using the "Funnel Technique": part 2. Clinical experience.

This study is a retrospective review of the clinical results of patients treated with thoracic pedicle screws using the "funnel technique." The objective is to report the clinical results of patients treated with thoracic pedicle screws using the funnel technique for screw placement. A total of 115 patients treated with the use of at least one thoracic pedicle screw were retrospectively identified. All patients were treated at a single medical center, under the senior author's supervision. Twenty-five different residents were responsible for placing 50-60% of these screws, and five different fellows and the senior author placed the remainder. The accuracy of screw placement and the complications related to the use of thoracic pedicle screws were analyzed by assessing intraoperative and postoperative charts and radiographs. There were 115 patients (age range 9-82 years) with the average follow-up period of 17 months. The total number of screws used was 348; the screw diameter ranged from 4.0 to 7.75 mm. There were no vascular or pulmonary complications. There was no iatrogenic neurologic injury, except for one patient who developed a transient anterior thigh numbness from intraoperative positioning. In fracture patients, 35% (10 of 28) had documented neurologic improvement postoperatively. There were no obviously misplaced pedicle screws on detailed review of intraoperative and postoperative radiographs. No screws had to be electively removed for complications related to misplacement. There were four broken screws, one broken rod, two loose screws, and three connector disengagements. Two patients had deep infections and four patients had pseudarthrosis requiring additional surgery. The clinical results proved that thoracic pedicle screws can be safely placed with the funnel technique.

Short segment bone-on-bone instrumentation for single curve idiopathic scoliosis.

STUDY DESIGN: Retrospective case series review. OBJECTIVES: To evaluate the outcomes of a new short segment anterior scoliosis technique with complete removal of the discs, bone-on-bone apposition of the vertebral bodies, and dual rod instrumentation. To evaluate a new preop planning technique for scoliosis instrumentation. SUMMARY OF BACKGROUND DATA: Scoliosis surgery traditionally was performed via a posterior approach, but anterior scoliosis instrumentation has proven to be superior regarding the amount of curve correction and the number of segments saved from instrumentation. METHODS: Thirty-one patients with single curve idiopathic scoliosis less than 75 degrees were operated using the bone-on-bone surgical technique with dual rod instrumentation (Kaneda Anterior Scoliosis System, Depuy AcroMed, Raynham, MA from 1996 until 2001). Average follow-up was 40 months (range 15-77 months). RESULTS: Surgical correction of the major curve averaged 73.9% over the instrumented levels and 51.4% over the entire curve. The average number of discs fused was 4.6 for thoracic curves and 3.3 for thoracolumbar and lumbar curves. There were no implant-related complications or nonunions. The compensatory curves spontaneously improved by an average of 38.6%. Uneventful healing of all fusions occurred-most within 8 to 12 weeks. One compensatory thoracic curve progressed and posterior instrumentation was done 28 months after correction of the major thoracolumbar curve. CONCLUSIONS: Surgical correction was achieved in over half the levels that would have been operated by standard posterior segmental fixation. Bony healing due to the bone-on-bone apposition was achieved uneventfully after apical correction of the spinal curvature in all patients. Use of dual rod instrumentation (Kaneda Anterior Scoliosis System) is fundamental in maintaining the correction of the curvature achieved in the operating room. The preoperative planning technique worked well.