Transpedicular fixation with Zielke instrumentation in the treatment of thoracolumbar and lumbar injuries

STUDY DESIGN: Sixty-five patients who underwent transpedicular fixation for thoracolumbar and lumbar injuries were studied for type of injury, the severity of paralysis, the degree of postoperative correction, and instrumentation failures. OBJECTIVES: To evaluate the surgical approaches and the selection of instrumentation to determine indications for using the transpedicular fixation procedure. SUMMARY OF BACKGROUND DATA: Various transpedicular fixation devices have been used for different type of injuries, and satisfactory postoperative results were not obtained in some studies. METHODS: Forty patients had burst fractures, 19 had fracture dislocations, and six had chance-type fractures. An anterior decompression procedure was used for most cases of burst fracture and some cases of fracture dislocation where anterior compression factors were present. The Zielke or modified Zielke system was used as an internal fixator for posterior segmental fixation. RESULTS: No patient had neurologic deterioration after surgery. Twenty of 28 patients with incomplete lesions improved postoperatively according to Frankel grades. The instrumentation failed in only one patient, in whom a nonunion developed. CONCLUSION: With transpedicular fixation, it is possible to provide solid internal fixation that is circumscribed to the injured vertebral segments. The elasticity of the Zielke rod makes it an excellent transpedicular fixation device because it is easily attached and reduction is easily performed. Anterior decompression with fusion needs to be used with transpedicular fixation in the treatment of injuries (especially burst fractures).     

High resting energy expenditure in normal-weight bulimics and its normalization with control of eating behaviour

Combined anterior and posterior fusion with posterior instrumentation may be indicated in the treatment of select cases of L5-S1 spondylolisthesis. The instrumentation, however, is expensive and usually bulky, occasionally requiring removal. In an effort to avoid these problems, an L5-S1 paralaminar screw technique was developed for posterior stabilization after an L5-S1 anterior interbody fusion. The technique involves the placement of cortical screws from the base of the articular process of S1 to the pedicle of L5. This study evaluates the anatomic applications and clinical results of this technique. The relationship between the screw and L5 nerve root was examined using five cadaveric specimens with olisthesis of 0, 25, 50, and 75%. This work demonstrates that the screws can only be inserted safely if an L5-S1 olisthesis of at least 25% is present. If < 25%, the screws will either impinge on or directly injure the L5 nerve root. In the clinical study, the outcomes of 20 patients who had an isthmic spondylolisthesis of 25-81% and were treated with partial reduction, L5-S1 anterior interbody fusion, and L5-S1 posterior paralaminar screw fixation were reviewed. Nineteen patients had adequate posterior stabilization to completely heal an L5-S1 anterior interbody fusion without loss of the correction. In one patient, a pseudarthrosis occurred secondary to poor surgical technique of both anterior and posterior fusions. This patient required an additional L4-S1 posterior fusion 9 months later and had a good clinical outcome. No other complications due to screw placement occurred. We conclude that this procedure can be used safely and reliably for the posterior stabilization of L5-S1 after stable anterior L5-S1 interbody fusion in residual slips of at least 25%. Prerequisites are proper patient compliance and low weight. Compared with other posterior instrumentation systems, this screw fixation is inexpensive and does not require implant removal. The disadvantages of the method are the degree of difficulty of the procedure and the limited clinical application to cases of L5-S1 spondylolisthesis with corrected residual slips of 25 to 50-60%. The procedure is technically demanding and should be limited to those surgeons who are comfortable with the method.     

Adding posterior lumbar interbody fusion to pedicle screw fixation and posterolateral fusion after decompression in spondylolytic spondylolisthesis

STUDY DESIGN: This is a retrospective study analyzing 76 patients treated by decompression, pedicle screw instrumentation, and fusion for spondylolytic spondyiolisthesis with symptomatic spinal stenosis. OBJECTIVES: To verify the advantages of adding posterior lumbar interbody fusion to the usual posterolateral fusion with pedicle screw instrumentation. SUMMARY OF BACKGROUND DATA: Stabilization after decompression of spondylolytic spondylolisthesis is difficult because of a lack of fusional bone bases, gap between the transverse process bases, and incompetent anterior disc support. Posterior lumbar interbody fusion offers anterior support, reduction, and a broad fusion base. METHODS: Forty patients were treated with posterolateral fusion, and 36 were treated with additional posterior lumbar interbody fusion. They were compared for union, reduction of the deformity, and clinical results. RESULTS: The patients were followed up for more than 2 years. Nonunion was observed in three patients who underwent posterolateral fusion (7.5%), and no cases of nonunion was found in patients who underwent posterior lumbar interbody fusion. Reduction of slippage was 28.3% in those who underwent posterolateral fusion and 41.6% in those who had posterior lumbar interbody fusion (P = 0.05). In the posterolateral fusion group, eight patients (20%) had recurrence of deformity, with loss of reduction more than 50%. Hardware failures occurred in two patients who had posterolateral fusion. There was no major neurologic complications in both groups. Both groups had satisfactory results in more than 90% of patients, with marked improvement of claudication. However, subjective improvement of back pain by Kirkaldy-Willis criteria revealed differences in the excellent results. An excellent result was reported by 45% in the posterolateral fusion group and by 75% in posterior lumbar interbody fusion group. CONCLUSIONS: The addition of posterior lumbar interbody fusion to posterolateral fusion after a complete decompression and pedicle screw fixation is a recommended procedure for the treatment of spondylolytic spondylolishesis with spinal stenosis.     

New anterior instrumentation for the management of thoracolumbar and lumbar scoliosis. Application of the Kaneda two-rod system

STUDY DESIGN: The Kaneda multisegmental instrumentation is a new anterior two-rod system for the correction of thoracolumbar and lumbar spine deformities. This system consists of a vertebral plate and two vertebral screws for individual vertebral bodies and two semirigid rods to interconnect the vertebral screws. Clinical results of 25 thoracolumbar and lumbar scoliosis patients treated with this new instrumentation were analyzed. OBJECTIVES: To evaluate the efficacy of the new anterior instrumentation in correction and stabilization of thoracolumbar and lumbar scoliosis. SUMMARY OF BACKGROUND DATA: Since Dwyer first introduced the concept of anterior spinal instrumentation and fusion for scoliosis, anterior surgery has gradually gained acceptance. In 1976, a useful modification for the anterior spinal instrumentation, which reportedly provided means of lordosation and vertebral body derotation, was described. However, some authors reported a high tendency of the implant breakage, loss of correction, progression of the kyphosis, and pseudoarthrosis as the major complications. To overcome the disadvantages of Zielke instrumentation, the authors have developed a new anterior spinal instrumentation (two-rod system) for the management of thoracolumbar and lumbar scoliosis. METHODS: Anterior correction and fusion using Kaneda multisegmental instrumentation was performed in 25 patients with thoracolumbar or lumbar scoliosis. The average follow-up period was 3 years, 1 month (range, 2 years to 4 years, 7 months). There were 20 patients with idiopathic scoliosis (13 adolescents and seven adults) and five patients with other types of scoliosis, including congenital and other etiologies. All patients had correction of scoliosis by fusion within the major curve, and for 16 of the 25 patients, the most distal end vertebra was not included in the fusion (short fusion). Radiographic evaluations were performed to analyze frontal and sagittal alignments of the spine. RESULTS: The average correction rate of scoliosis was 83%. Over the instrumented levels, the correction rate was 90%. Preoperative kyphosis of the instrumented levels of 7 degrees was corrected to 9 degrees of lordosis. Sagittal lordosis of the lumbosacral area beneath the fused segments averaged 51 degrees before surgery and was reduced to 34 degrees after surgery. The trunk shift was improved from 25 mm before surgery to 4 mm at final follow-up evaluation. The average improvement in the lower end vertebra tilt-angle was 97% in those patients whose lower end vertebra was included in the fusion and 83% in patients whose lower end vertebra was not included in the fusion. Apical vertebral rotation showed an average correction rate of 86%. At final follow-up evaluation, all patients demonstrated solid fusion without implant-related complications. There was 1.5 degrees of frontal plane and 1.5 degrees of sagittal plane correction loss within the instrumented area at final follow-up evaluation. CONCLUSIONS: New anterior two-rod system showed excellent correction of the frontal curvature and sagittal alignment with extremely high correction capability of rotational deformities. Furthermore, correction of thoracolumbar kyphosis to physiologic lordosis was achieved. This system provides flexibility of the implant for smooth application to the deformed spine and overall rigidity to correct the deformity and maintain the fixation without a significant loss of correction or implant failure compared with conventional one-rod instrumentation systems in anterior scoliosis correction.     

1997 Volvo Award winner in clinical studies. Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation

STUDY DESIGN: This prospective study analyzed the influence of transpedicular instrumented on the operative treatment of patients with degenerative spondylolisthesis and spinal stenosis. OBJECTIVES: To determine whether the addition of transpedicular instrumented improves the clinical outcome and fusion rate of patients undergoing posterolateral fusion after decompression for spinal stenosis with concomitant degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Decompression is often necessary in the treatment of symptomatic patients who have degenerative spondylolisthesis and spinal stenosis. Results of recent studies demonstrated that outcomes are significantly improved if posterolateral arthrodesis is performed at the listhesed level. A meta-analysis of the literature concluded that adjunctive spinal instrumentation for this procedure can enhance the fusion rate, although the effect on clinical outcome remains uncertain. METHODS: Seventy-six patients who had symptomatic spinal stenosis associated with degenerative lumbar spondylolisthesis were prospectively studied. All patients underwent posterior decompression with concomitant posterolateral intertransverse process arthrodesis. The patients were randomized to a segmental transpedicular instrumented or noninstrumented group. RESULTS: Sixty-seven patients were available for a 2-year follow-up. Clinical outcome was excellent or good in 76% of the patients in whom instrumentation was placed and in 85% of those in whom no instrumentation was placed (P = 0.45). Successful arthrodesis occurred in 82% of the instrumented cases versus 45% of the noninstrumented cases (P = 0.0015). Overall, successful fusion did not influence patient outcome (P = 0.435). CONCLUSIONS: In patients undergoing single-level posterolateral fusion for degenerative spondylolisthesis with spinal stenosis, the use of pedicle screws may lead to a higher fusion rate, but clinical outcome shows no improvement in pain in the back and lower limbs.     

Evidence for eosinophil activation in bronchiectasis unrelated to cystic fibrosis and bronchopulmonary aspergillosis: discrepancy between blood eosinophil counts and serum eosinophil cationic protein levels

The purpose of this prospective study was to evaluate the effect of prophylactic antibiotic treatment on postoperative antibiotic spinal wound infection after spinal surgery with instrumentation. Subjects consisted of 110 successive patients that underwent instrumented fusion with Cotrel-Dubousset (CD) or Miami Moss instrumentation. In 56 cases, the indication for surgery was painful spondylolisthesis. The remaining 54 patients were treated for idiopathic scoliosis. In total, 172 spinal procedures were performed and included in the study. Preoperative infection prophylaxis consisting of 2 g cefamandole was administered to all patients. Patients received three doses of 2 g/day cefamandole after surgery for 3 days. Follow-up ranged from 1 to 4 years. The study revealed an early infection in one (0.6%) of the 172 procedures in a patient with spondylolisthesis. A late infection occurred in one (0.6%) patient with the diagnosis of idiopathic scoliosis. In both cases, cultures were positive for Staphylococcus aureus.     

Single-level posterolateral arthrodesis, with or without posterior decompression, for the treatment of isthmic spondylolisthesis in adults. A prospective, randomized study

Forty-two neurologically intact adults in whom non-operative treatment of grade-I or grade-II isthmic spondylolisthesis of the most caudad lumbar segment had failed were entered into a prospective study of the results of operative treatment. Twenty patients who smoked were managed with a posterolateral arthrodesis with instrumentation (transpedicular fixation), and twenty-two patients who did not smoke were managed with a posterolateral arthrodesis without instrumentation. Of the patients who were managed with instrumentation, eight were randomized to treatment with a decompressive laminectomy and twelve, to treatment without it; in the group that was managed without instrumentation, the distribution was ten and twelve patients, respectively. The patients were followed clinically for a mean of 4.5 years (range, 3.5 to six years). Of the eighteen patients who had been managed with decompression, four had a pseudarthrosis and six had an unsatisfactory result compared with none and one of the twenty-four who had been managed without decompression (p = 0.02 and p = 0.01, respectively). In the group of twenty patients (smokers) who had been managed with instrumentation, none of the twelve managed without decompression had a pseudarthrosis compared with one of the eight managed with decompression (p = 0.2). In the group of twenty-two patients (non-smokers) who had been managed without instrumentation, none of the twelve managed without decompression had a pseudarthrosis compared with three of the ten managed with decompression (p = 0.04). In the group managed with instrumentation, two of the eight who had had decompression had an unsatisfactory result compared with none of the twelve who had not had decompression. In the group managed without instrumentation, four of the ten who had had decompression had an unsatisfactory result compared with one of the twelve who had not had decompression. The addition of decompression to arthrodesis, performed with or without instrumentation, for the treatment of low-grade isthmic spondylolisthesis in patients who do not have a serious neurological deficit does not appear to improve the result and may significantly increase the rates of pseudarthrosis and unsatisfactory results.     

Repair of defects in spondylolysis by segmental pedicular screw hook fixation. A preliminary report

STUDY DESIGN: Clinical testing of segmental pedicular screw hook fixation repairing defects in lumbar spondylolysis. OBJECTIVES: The authors tested segmental pedicular screw hook fixation using ISOLA implants (AcroMed Corp., Cleveland, OH) to maintain direct repair of the defect in pars interarticularis while fusion occurs. The device should not break while fusion takes place with out a postoperative body cast. SUMMARY OF BACKGROUND DATA: Previous techniques of direct repair of defects in lumbar spondylolysis have not been successful universally, and wire breakage has occurred despite the use of a postoperative body cast. METHODS: This technique stabilizes bone grafted to the detect by a pedicular screw, a hook, and a rod used in combination. Six patients with lumbar spondylolysis were treated by means of this technique. RESULTS: Postoperatively, all patients with low back pain or radicular pain experienced significant relief. Radiographs, including lateral flexion-extension radiographs and tomograms, showed five patients to have a bilateral union and one a unilateral union, and none of the instrumentation failed. CONCLUSION: This technique is considered useful for direct repair of the defects found in lumbar spondylolysis.     

Anterior vertebral body screw pullout testing. A comparison of Zeilke, Kaneda, Universal Spine System, and Universal Spine System with pullout-resistant nut

STUDY DESIGN: A biomechanical study of pullout of anteriorly implanted screws in cadaveric vertebral bodies. OBJECTIVES: To investigate and compare the pullout strength of the Zielke, Kaneda, Universal Spine System (USS) pedicle screw, and USS pedicle screw with a new pullout-resistant nut. SUMMARY OF BACKGROUND DATA: A common problem with anterior purchase regardless of the implant system is screw pullout at the proximal and distal ends of multilevel constructs. There is limited information on a solution to this problem. METHODS: The L1 to L4 vertebral bodies from four cadavers had one each of Zielke and Kaneda pedicle screws (Acromed Corp., Cleveland, OH), USS pedicle screw (Synthes Spine, Paoli, PA), and USS pedicle screw with pullout-resistant nut implanted transversely across the center of the vertebral body with bicortical purchase in a similar fashion as would be used clinically. The screws were extracted using a servohydraulic material testing system. The maximum axial forces were recorded. RESULTS: The Zielke and Kaneda screws had no significant difference in mean pullout strength (P = 0.542). The USS screw alone was less strong (P = 0.009). The USS screw and pullout-resistant nut increased the pullout strength by twofold (P = 0.00006). In the screw pullout tests, the mode of failure was at the screw thread's interface. The USS screw and pullout-resistant nut failed by imploding the body around the nut. With the USS screw and pullout-resistant nut, the pullout strength was determined by the compressive strength of the bone. CONCLUSIONS: The addition of a pullout-resistant nut to an anterior vertebral body screw improves the pullout strength by twofold and changes the mode of failure to rely ultimately on the inherent vertebral body strength rather than the screw's characteristics. The addition of a pullout-resistant nut may be applicable to multilevel implant constructs to prevent screw pullout at the top and bottom.     

Spinal instrumentation with a low complication rate

BACKGROUND: Spinal instrumentation has become an increasing part of the armamentarium of neurosurgery and neurosurgical training. For noncontroversial indications for spine fusion the arthrodesis rate seems to be better. For both noncontroversial and controversial indications, the reported complication rate with spinal instrumentation tends to be greater than that with noninstrumented spine surgeries. These reported complications include a 2-3% neurologic injury rate, 3-45% reoperation rate for implant failure, and inflection rates of 5-10%. Therefore, we report on 299 cases that have undergone spinal instrumentation placed exclusively by neurosurgeons with a very low complication rate. METHODS: Two hundred ninety-nine consecutive spinal instrumentation cases performed exclusively by neurosurgeons at Indiana University Medical Center were analyzed for complications related to spinal instrumentation. The spinal instrumentation placed consisted of 195 anterior cervical locking plates, 22 cases of posterior cervical instrumentation, 9 cases of combined anterior locking plates with posterior cervical instrumentation, 14 anterior thoracolumbar plates, 51 posterior thoraco-lumbar instrumentation cases, and 8 combined anterior/posterior thoracolumbar instrumentation cases. RESULTS: The mean follow-up is 40 months (6-95). There was one perioperative death unrelated to the spinal instrumentation. There were no neurologic injuries and there has been no hardware infection to date. There were two dural tears, three superficial wound infections, and three minor wound breakdowns successfully treated. Hardware complications included three cervical plate/screw extrusions reoperated, one cervical plate fracture reoperated, one posterior cervical screw backout not reoperated, one case of broken pedicle screw not reoperated, one vertebral body failure not reoperated, and one posterior rod case reoperated for excessive rod length and protrusion. The overall complication rate attributable to placement of spinal instrumentation was 10/299 (3%) with a reoperation rate of 2%. The arthrodesis rate was 298/299 (99%). CONCLUSION: The complication rate for using spinal instrumentation can be less than previously reported. Lessons learned and discussed should reduce the rate even more. Spinal instrumentation is a safe and useful adjunct to fusion in treating degenerative, traumatic, infectious, and neoplastic diseases of the spine.     

Spinal deformity in myelodysplasia. Correction with posterior pedicle screw instrumentation

STUDY DESIGN: A retrospective review of transpedicular instrumentation used in a series of 24 patients with myelodysplastic spinal deformities and deficient posterior elements. OBJECTIVE: To describe the usefulness and efficacy of these instruments in the treatment of complicated myelodysplastic spinal deformity. METHODS: The mean preoperative scoliosis was 75.7 degrees (range, 39-130 degrees) in the 22 patients with scoliotic deformities; 4 patients with thoracic hyperkyphoses averaged 70.5 degrees (range, 46-90 degrees) and 10 patients with lumbar kyphoses averaged 80.5 degrees (range, 42-120 degrees). The instrumentation extended to the sacrum in 4 patients and the pelvis in 9; 10 patients also underwent anterior release and fusion and 7 underwent concomitant spinal cord detethering. At an average follow-up of 4.0 years (2.0-7.7 years; one patient died at 8 months), all patients have fused (with the exception of two lumbosacral pseudarthroses). RESULTS: At last follow-up, deformity measured 32.1 degrees scoliosis (range, 6-85 degrees), 30.8 degrees thoracic kyphosis (range, 24-35 degrees), and 0.0 degree lumbar kyphosis (range, 35 degrees kyphosis to 29 degrees lordosis). Three patients lost some neurologic function after surgery; two recovered within 6 months and one has incomplete recovery. No ambulatory patient lost the ability to walk. Five patients required additional surgical procedures; in three cases, there was instrumentation breakage associated with pseudarthrosis or unfused spinal segments. CONCLUSIONS: Pedicle screw instrumentation is uniquely suited to the deficient myelodysplastic spine. Compared with historical control subjects, these devices have proven capable of significant correction of both scoliotic and kyphotic deformities. This instrumentation appears particularly useful in preserving lumbar lordosis in all patients and may preserve more lumbar motion in ambulatory myelodysplasia patients.     

Pedicle screw placement using image guided techniques

Clinical evaluation of a computer assisted spine surgical system is presented. Eighty pedicle screws were inserted using computer assisted technology in thoracic and lumbar vertebrae for treatment of different types of disorders including fractures, spondylolisthesis, and scoliosis. Fifty-two patients with severe fractures, spondylolisthesis, or pseudoarthrosis of T10 to L5 were treated using a computer assisted technique on 1/2 the patients and performing the screw insertion manually for the other 1/2. At the same time, 28 pedicle screws were inserted in T12 to L4 vertebrae for scoliosis with the help of the computer assisted technique. Surgery was followed in all cases (66 vertebrae; 132 pedicle screws) by postoperative radiographs and computed tomographic examination, on which measurements of screw position relative to pedicle position could be done. For fractures, spondylolisthesis, or pseudarthrosis, comparison between the two groups showed that four screws in 52 (8%) vertebrae had incorrect placement with computer assisted technique whereas 22 screws in 52 (42%) vertebrae had incorrect placement with manual insertion. In patients with scoliosis, four screws in 28 (14%) vertebrae had incorrect placement. In all of the patients (132 pedicle screws) there were no neurologic complications. These results show that a computer assisted technique is much more accurate and safe than manual insertion.     

A survey on drug abuse in young males in Longchuan County, Yunnan Province

Complications occur frequently after surgical treatment of scoliosis. In order to prevent from them effectively, 101 cases with failure and postoperative complications were analysed. They included rod fracture in 22 cases (15 Harrington rods, 4 Zielke rods, and 3 Luque rods); recurrence of curve severity in 12 cases; broken or loossened luque wires in 15 cases; loss of thoracic kyphosis (flat back) in 6 cases; progressive kyphosis with or without paraplegia following incorrect posterior decompression in 5 cases; and increased unbalance of shoulders after instrumentation in 2 cases due to neglect of the tilting of the first thoracic vertebra. Infection occurred in 8 cases (incision infection 7 cases; deep wound infection in 1 case); and pneumothorax in 1 cases. They were induced by biomechanical factors in 23 cases (22.77%), incorrect selections of indications in 29 cases (28.71%), oprational mistakes in 37 cases (36.63%), internal fixation factors in 15 cases (14.85%). The authors hold that there are quite a lot of factors leading to occurrence of complications and the effective way for prevention from them is to understand the factors and main technical points related to internal fixation.     

Coexistence of enkephalin- and tyrosine hydroxylase-like immunoreactivities in nerve fibers of the temporomandibular joint capsule of the guinea pig

This case report describes the intraoperative improvement of somatosensory evoked potentials (SEPs) during the removal of a broached pedicle screw that had been placed in an unmonitored procedure 1 month earlier. Postoperatively, there was improved neurologic function and reversal of the neurologic deficit that had been caused by the first procedure. To our knowledge, this is the first report of a correlation of intraoperative SEP improvement with improved postoperative neurologic function after neurologic deficit because of nerve irritation or compression from a pedicle screw. Nerve damage occurs in about 15% of patients who undergo instrumentation after lumbar fusion. The potential utility of neurophysiologic methods during initial screw placement is suggested and supported, as proper use of such intraoperative tools may have prevented the need for the second procedure.     

Possibilities of ambulation in children with myelodysplasia]

This article reviews four reports that have addressed the efficacy of spinal instrumentation to enhance spinal fusion in patients with degenerative spondylolisthesis. These papers serve to highlight some of the common problems with interpreting and applying the clinical findings of such studies: small, nonuniform patient selection; variable instrumentation techniques; relatively brief follow-up periods (usually less than 5 years); lack of a uniform scale for clinical assessment of patients; and lack of consensus on the definition and clinical documentation of motion segment instability.     

Review of 87 cases of scoliosis surgically treated

BACKGROUND: The authors compared the results and complications in surgical treatment of idiopathic scoliosis with Harrington's rod instrumentation with subtrasversal wires in dorsal treat. METHODS: A research on 87 cases operated on for idiopathic scoliosis from 1987 to 1995 is carried out. The 87 cases include 65 females and 25 males, 16 years old in average (range, 11 to 30). The curvature in Cobb's degrees and rotation of vertebrae with Raimondi's method on radiographs take just before, 15 days later and an year later on operation was measured. The patients have been divided into two groups: the first of 77 patients operated with Harrington's rod instrumentation; the second of 10 patients operated with Harrington's rod instrumentation and subtrasversal wires. RESULTS: In a general analysis without taking in to consideration the type and the seriousness of curvature it was obtained a better correction and derotation of vertebrae in patients of second group. The same group with wires had obtained a better correction and derotation of vertebrae in dorsal scoliosis from 40 degrees to 60 degrees and in the double scoliosis, while the first group obtained better results in dorsal scoliosis from 60 degrees to 80 degrees and in derotation of vertebrae on dorsal treat of double scoliosis. One case of pseudarthrosis in every group was observed. Any neurological complication were observed. CONCLUSIONS: The conclusions is drawn that the application of subtrasversal wire improves the Harrington's technique for the correction and derotation of dorsal and double scoliosis without neurological complications sometimes present with subliminar wires.     

Plasticity and stem cells in the vertebrate nervous system

One hundred and seventy-two children with cerebral palsy were operated on for neuromuscular scoliosis by spinal fusion with unit rod instrumentation between January 1988 and June 1996. There were 15 (8.7%) postoperative wound infections (seven deep, eight superficial) in 15 patients (five males, 10 females) who had a mean age of 13.9 years. The mean follow-up after diagnosis of infection was 3.3 years (range, 1-7.2). Twelve of the 15 infected cases, including all seven deep infections, occurred in the distal portion of the incision. In 14 patients, the wound infections were diagnosed within the first 2 months of the original spinal fusion. All the superficial wound infections were treated successfully by local wound care and intravenous antibiotics. The removal of hardware was necessary in the one late deep wound infection that occurred 2 years after the spinal fusion. The remaining six deep infections were treated by irrigation and debridement with the wound left open, allowing it to heal by secondary intention. One patient's wound was closed over suction-irrigation drains; however, due to a recurrent abscess, the wound was reopened and allowed to granulate. All the wound infections occurred in severely neurologically involved spastic quadriplegics who were nonambulatory and severely mentally retarded and had seizure disorders.     

Longitudinal element size effect on load sharing, internal loads, and fatigue life of tri-level spinal implant constructs

The effects of implant stiffness on load sharing and stress shielding, of vertebral column load sharing on implant fatigue life, and of instrumenting two versus one level adjacent to a comminuted segment on implant internal loads were studied. Finite element models of six screw constructs with 4.76 mm rod; 6.35 mm rod, and VSP plate tri-level instrumentation of two motion segments (healthy vertebra case and comminuted) and an adjacent healthy motion segment with dimensions representative of the human lumbar spine were used. Also a simplified model was developed to predict the percent of axial load passing through the column, which is a function of ki/kv the ratio of implant axial stiffness to instrumented vertebral column axial stiffness. For constructs with dimensions typical of the human lumbar spine, 77 to 80% of the axial load was predicted to pass through one or two healthy motion segments when instrumented with either 6.35 mm rod or VSP plates, compared to 90% when instrumented with 4.76 mm rods. When instrumenting smaller motion segments (in dogs) for comparison, 60% of the axial load was predicted to pass through the column for 4.76 mm rod and 33% for 6.35 mm rod constructs due to increased implant stiffness ki as a result of decreased AP and longitudinal construct dimensions, and lower canine motion segment stiffness kv.(ABSTRACT TRUNCATED AT 250 WORDS)     

Orthofix external fixation of distal radius fractures: complications associated with screw size

We did a retrospective analysis of 28 patients who were treated with the Orthofix external fixation system for complex fractures of the distal radius to study complications associated with screw size. The 14 patients in group 1 had a 4.5/3.5-mm tapered screw placed in the metacarpal bone; the 14 patients in group 2 had a 3.5/3.3-mm tapered screw placed in the metacarpal bone. Both groups had 4.5/3.5-mm tapered screws placed in the radius. Two patients in group 1 had metacarpal pin tract infections; no patients in group 2 had a distal pin tract infection. Two patients in group 1 had a fracture of the metacarpal; only one patient in group 2 had a fracture of the metacarpal. In both groups two patients had proximal pin tract infections at the radius screw fixation site. There was no screw breakage in either group. The unique design of the tapered Orthofix screw allows it to be removed almost painlessly in the clinic. At installation in the operating room, however, the surgeon must remember not to back the threaded pin out for fine adjustment of bony penetration. Any reverse excursion of the threaded shaft will loosen the tapered screw and cause early failure of the fixation. We no longer use the 4.5/3.5-mm screw when managing wrist fractures with the Orthofix external fixation system. It is now our policy to use the 3.5/3.3-mm screw for fixation of the Orthofix external frame to both the metacarpal bone and the radius.     

Defects of pars interarticularis in athletes: a protocol for nonoperative treatment

The purpose of this study was to report the results of a specific treatment protocol for athletes with spondylolysis or spondylolisthesis of the lumbar spine. A retrospective study with recent follow-up was performed on 82 patients treated with restriction of activity, bracing, and physical therapy. All of the patients were involved in sports at first onset of symptoms. Sixty-six patients were boys and 16 were girls. Activities involving repetitive hyperextension and/or extension rotation of the lumbar spine were described as painful in 98% of the patients. Of the 62 patients with spondylolysis, 53 (85%) had an L5 defect and nine (15%) an L4 defect (90% of these 62 patients' defects were located in the most caudad mobile vertebra). Thirty-seven patients had bilateral pars defects, and 25 had unilateral defects. Eight patients had normal roentgenograms, but these eight had abnormal bone scans. Nine patients with spondylolysis underwent posterolateral fusion. Average follow-up was 4.2 years. Fifty-two (84%) had excellent results, eight had good results, and two had fair results. Twenty patients had a spondylolisthesis: 12 were grade I, six were grade II, and two were grade III. Twelve patients (60%) required surgery; 9 had excellent results, one had good results, one had a fair result, and one had a poor result. Pars defects must be suspected in the differential of low back pain in young athletes. Oblique radiographs are frequently diagnostic; however, if the history and examination are suggestive despite normal plain films, a bone scan should be obtained. Nonoperative management of pars defects is frequently successful.(ABSTRACT TRUNCATED AT 250 WORDS)