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Study Design: A retrospective multicenter study., Objective: To evaluate the effect of repeated surgical lengthenings and time on spinal growth and Cobb angle in children with early onset scoliosis and dual growing rods., Summary of Background Data: Previous studies have established the effectiveness of dual growing rods for controlling spinal deformity and promoting spinal "growth." Although anecdotal experience suggests that the effectiveness of repeated lengthenings decreases over time, this has not been previously studied., Methods: Medical records from five different centers were reviewed to identify children treated with dual growing rods for early onset scoliosis who had a minimum of 2-year follow-up and at least three lengthening procedures. Initial radiographs, postimplantation radiographs, and radiographs from before and after each lengthening were measured for T1-S1 distance and Cobb angle. Linear regression and analysis of variance were used for statistical analysis., Results: Thirty-eight patients from five centers met the inclusion criteria. The average age of our patients was 5.7 years (range 1.7-8.9 years); mean follow-up was 3.3 years (range 2-7 years). The average interval between lengthenings was 6.8 months. Cobb angle decreased from a mean value of 74° preoperatively to 36° after the primary implantation and did not change significantly with repeated lengthenings (P = 0.96). After initial implantation, the average annual T1-S1 gain was 1.76 ± 0.71 cm/year. The T1-S1 gain after a given lengthening, however, decreased significantly with repeated lengthenings (P = 0.007). When the effect of time was considered, there was also a significant decrease in T1-S1 gain over time (P = 0.014)., Conclusion: There seems to be a "law of diminishing returns" with repeated lengthenings of dual growing rods. Repeated lengthenings still result in a net T1-S1 increase; however, this gain tends to decrease with each subsequent lengthening and over time. This phenomenon may be due to autofusion of the spine from prolonged immobilization by a rigid device.

Study Design: A new rod-plate anterior implant was designed to provide plate fixation at the cephalad and caudal-end segments of a 5-level anterior spine construct. Biomechanical testing was performed on calf spines instrumented with 5-segment anterior scoliosis constructs. OBJECTIVES.: To analyze the initial and post-fatigue biomechanical performance of the new implant, and compare it to an anterior dual-rod construct and a single-rod construct with interbody cages., Summary of Background Data: Using single-rod anterior instrumentation for thoracolumbar and lumbar scoliosis, an unacceptable incidence of loss of correction, segmental kyphosis, and pseudarthrosis has been reported. Inadequate construct stiffness due to early postoperative bone-screw interface failure, especially at cephalad and caudal-end vertebrae, has been implicated as the cause of these complications., Methods: Thirty calf spines were instrumented over 5 segments with: (1) single-rod augmented with rod-plate implants, (2) dual-rod construct, and (3) single-rod with titanium mesh cages. Stiffness in flexion-extension and lateral bending modes was determined initially and post-cyclical loading by measuring segmental range of motion (ROM). Post-fatigue screw pullout tests were also performed., Results: In lateral bending, the caudal-end segmental ROM for rod-plate construct was 54% less than single-rod with cages construct (P < 0.05), with no difference between rod-plate and dual-rod constructs. In flexion-extension, the rod-plate construct showed 45% to 91% (initial test) and 84% to 90% (post-fatigue) less ROM than the single-rod with cages construct (P < 0.001). Again, there was no difference between rod-plate and dual-rod constructs at the cephalad and caudal-end segments. Post-fatigue screw pullout strengths of the rod-plate construct were significantly greater than those of the dual-rod and single-rod with cages constructs (P < 0.05)., Conclusions: The rod-plate construct was significantly stiffer and provided greater stability of bone-screw interface than the single-rod with cages construct. It achieved similar stiffness and improved bone-screw interface stability compared to dual-rod construct.

Study Design: Movement analysis of spinal motion., Objective: To compare spinal motion among females with normal spines, those with idiopathic scoliosis who had not had spinal fusion, and those who had undergone fusion for idiopathic scoliosis., Summary of Background Data: Previous reports have documented loss of spinal motion following fusion for idiopathic scoliosis in adolescents and adults. To our knowledge, comparison to control groups both with and without scoliosis that have not had spinal fusions has not been performed to date., Methods: A total of 91 females between the ages of 15 and 28 years underwent computerized movement analysis. There were 34 fused patients, 32 unfused patients, and 25 healthy controls. The fused patients were divided into 3 groups: (1) 21 patients who had thoracic fusions that extended distally to T11, T12, or L1; (2) 6 patients with thoracic fusions ending at L2; and (3) 7 patients with thoracolumbar or lumbar fusions extending to L3 or L4. Marker triads were placed at C7-T1, T12-L1, and on the pelvis. Forward bend, extension, and left and right lateral bend were measured and divided into thoracic and lumbar motion., Results: There was no difference in any motion between the control and unfused groups. There was overall 25% less total spinal motion in the surgical groups compared to the unfused group. Patients who had thoracic fusions had diminished thoracic motion, especially lateral bending, whereas those who had lumbar fusions had the least lumbar motion, particularly on forward bend and lateral bend maneuvers. There was no compensatory hypermobility of the unfused segments in the surgical group., Conclusions: Diminished spinal motion can be measured in patients who have had spinal fusions. Although stiffness in the operated curves should be expected, compensatory hypermobility in the unfused segments does not occur, resulting in a net loss of flexibility compared to controls.

Study Design: Retrospective review case series., Objective: To evaluate the incidence, patterns, and treatment of scoliosis in a Down syndrome population., Summary of Background Data: Despite a preponderance of literature concerning cervical abnormalities in Down syndrome, there is little information concerning scoliosis in this patient group. We examined the 50-year history of treating scoliosis at our institution in patients with Down syndrome., Methods: Following institutional review board approval, chart review identified patients with Down syndrome with scoliosis. We performed a radiographic review of curve pattern, and determined results of brace and operative treatment., Results: A total of 379 patients were identified as having Down syndrome. There were 33 patients diagnosed with scoliosis, for an incidence of 8.7%. Mean follow-up was 4.15 years (range 0-12). The double major curve predominated with 18 (55%). Of 33 patients, 16 (49.5%) had previously undergone thoracotomy for congenital heart defects. There were 8 (24%) patients who were braced for an average of 26.5 months (range 12-63), with an average progression in brace of 10 degrees (range 0 degrees-44 degrees), 3 of whom went on to spinal fusion. There were 7 (21.2%) patients who underwent spinal fusion, including 6 posterior spinal fusions and 1 anterior spinal fusion. Four patients had complications, including 3 pseudarthroses, 4 implant failures, 3 superior junctional kyphosis, and 1 infection, for a 57% complication rate., Conclusions: Scoliosis developed in 8.7% of patients with Down syndrome. There was a high rate of cardiac surgery within this population. Bracing was ineffective for the majority of the patients treated. Although surgery has a high rate of complications, there was only one patient who underwent reoperation.

Study Design: Retrospective clinical and radiographic review., Objective: To assess the need for anterior apical release and fusion before posterior threaded rod compression instrumentation and closing-wedge lamina resection for the treatment of adolescent hyperkyphosis., Summary of Background Data: Traditional treatment of adolescent hyperkyphosis has included a preliminary anterior release and fusion of apical disc segments to achieve and maintain better correction., Methods: A total of 27 patients undergoing correction of adolescent hyperkyphosis with posterior threaded rod Texas Scottish Rite Hospital instrumentation was reviewed. Of the 27 patients, 19 had strict Sorensen criteria for Scheuermann kyphosis. There were 20 patients (group 1) who underwent posterior surgery only, while 7 (group 2) underwent same day preliminary open or endoscopic anterior release and fusion of 5-7 apical segments. A closing-wedge laminar resection was used to facilitate shortening of the posterior column. All but 2 patients were braced for up to 3 months after surgery. Preoperative, immediate postoperative, and final follow-up radiographs at 24-56 months postoperatively were analyzed for the amount and loss of correction of measured kyphosis, T2-T12 kyphosis, T10-L2 kyphosis, T12-S1 lordosis, C7 plumbline sagittal balance, and correction of Voutsinas index., Results: There was no difference in the amount of correction achieved at final follow-up between the 2 groups (group 1 = 53%, group 2 = 46%, P = 0.47). There was also no difference (P = 0.84) in the amount of correction immediately after surgery compared to final follow-up. No patient lost more than 8 degrees correction after surgery. One asymptomatic rod fracture occurred, with no loss of correction, implying no pseudarthroses. Similarly, there were no differences in any of the other sagittal plane measurements between the 2 groups, except for Voutsinas index (VI) in which group 1 patients had better normalization (VI = 0.11) compared to group 2 (VI = 0.15, P =0.05)., Conclusions: Traditional anterior/posterior fusion technique provides no additional improvement in radiographic outcome compared to posterior-only surgery for adolescent hyperkyphosis. Preliminary anterior release and fusion is no longer performed when correcting this deformity with a posterior column shortening procedure and threaded rod compression instrumentation.

Calcaneus gait is a known complication of surgical treatment of clubfoot, and is characterized by weak triceps surae strength combined with limited ankle plantarflexion at terminal stance, preventing adequate power generation. We evaluated the results of attempted reconstruction of this functional disturbance in 13 symptomatic patients (17 feet) using kinematic and kinetic analysis at a minimum of 1 year postoperatively. Three types of procedures were performed: group 1 (n=7) received calcaneal osteotomy alone; group 2 (n=6) received calcaneal osteotomy or hindfoot fusion combined with tendon transfers to the heel; and group 3 (n=4) received tendon transfers only. Kinematic results showed that none of the procedures was effective in increasing plantarflexion at toe-off. Kinetic analysis showed that plantarflexion power of group 1 and 2 feet actually worsened following surgery, while in group 3 there was mild improvement. Patients in group 3 were 5 years younger on average than those in groups 1 and 2, suggesting that if any objective benefit from surgery is to be gained, reconstruction should be performed prior to age 6 years. We conclude that calcaneus gait as a complication of clubfoot surgery is far better avoided than salvaged by attempted reconstruction, which in this series was ineffective.

Study Design: A retrospective multicenter study was conducted to investigate patients with a major thoracolumbar/lumbar adolescent idiopathic scoliosis and an associated minor thoracic curve treated with an anterior instrumentation and fusion of the lower curve., Objective: To establish criteria for determining when such curves can be successfully treated by an anterior only procedure of the lower curve with acceptable spinal balance and residual thoracic curve., Summary of Background Data: Anterior spinal instrumentation techniques have been proved effective for the management of isolated thoracolumbar/lumbar scoliosis with small compensatory thoracic curves. The success of a selective anterior fusion when the associated thoracic curve had some structural changes in a small preliminary study was variable and was the stimulus for this study., Methods: A multicenter study involved 49 adolescent patients with a major thoracolumbar/lumbar curve in which the associated minor thoracic curve measured between 30 degrees and 55 degrees. In all the patients, the apical vertebra of the lower curve lay outside the midsacral line, and the thoracic apical vertebra fell outside a line dropped from the center of C7. Multiple radiographic parameters were evaluated. The Risser sign, height, weight, onset of menses, and closure of the triradiate cartilages were studied to access the patients' maturity. All the patients were observed at least 2 years. Patients were considered to have a satisfactory result if the thoracic curve at the final follow-up assessment measured 40 degrees or less, if balance and sagittal alignment were reasonable, and if additional procedures were not required., Results: At final follow-up assessment, two groups emerged. Group 1 (n = 43) had satisfactory results. The preoperative thoracic curve in this group averaged 40 degrees and 26 degrees after surgery. The lumbar curve averaged 56 degrees before surgery and 22 degrees after surgery. Group 2 (n = 6) had unsatisfactory results. The average thoracic curve was 49 degrees before surgery 54 degrees after surgery, whereas the lumbar curve averaged 59 degrees before surgery and 27 degrees after surgery. Three of these patients underwent posterior thoracic instrumentation and fusion., Conclusions: Statistical analysis showed that a successful surgical outcome was dependent on both the structural changes in the thoracic curve and the patient's maturity. The thoracolumbar/lumbar-thoracic (TL/L:T) Cobb ratio in combination with the degree of the thoracic curve on lateral bending was the best predictor among the structural indexes. Of 44 patients with a TL/L:T Cobb ratio of 1.25 or greater and/or a thoracic curve, which bent out to 20 degrees or less, 42 had a satisfactory result. The best predictor among the maturity indexes was closure of the triradiate cartilages. Of 43 patients in whom the triradiate cartilages were closed, 42 had satisfactory results. When this data is combined, the outcome for the thoracic curve can be reasonably predicted.

Study Design: A retrospective radiographic study was conducted to analyze 50 consecutive adolescents with thoracolumbar-lumbar scoliosis treated with single solid-rod anterior instrumentation and either rib strut or morsellized interbody bone grafting technique., Objectives: To evaluate the effect of grafting technique on the maintenance of coronal and sagittal plane correction and alignment and the incidence of pseudarthrosis., Summary of Background Data: Loss of scoliosis correction and progressive kyphosis in the instrumented segment associated with radiographic pseudarthrosis have historically been disadvantages of the anterior technique used to correct thoracolumbar-lumbar scoliosis., Methods: All the patients underwent anterior discectomy, spinal fusion, and correction with Texas Scottish Rite Hospital instrumentation, with rib strut grafts used in 18 patients to "prop open" disc spaces below L1 and simple morsellized bone graft used in 32 patients. Most of the patients were instrumented from T11-L3 or T10-L2. Maintenance of coronal and sagittal plane correction and alignment was determined from the preoperative, immediate postoperative, and final follow-up radiographs., Results: Scoliosis correction was 72% immediately after surgery, but with an average 6 degrees loss of correction, it was 61% at follow-up evaluation. Final correction of apical vertebral translation was 69%, and trunk shift was 86%. Ten patients lost more than 10 degrees of scoliosis correction. In the sagittal plane, the instrumented segment was corrected initially from a mean of 3 degrees kyphosis to -1 degrees lordosis, but then had settled to 7 degrees kyphosis at follow-up evaluation. Progressive kyphosis exceeding 10 degrees in the instrumented segment was found in 19 patients. The technique of grafting had no effect on the maintenance of correction or sagittal alignment. Rib strut grafting did demonstrate a decreased incidence of pseudarthrosis, as compared with morsellized grafting (P = 0.029). Not unexpectedly, patients with pseudarthrosis had an increased incidence of correction loss, progressive kyphosis in the instrumented segment, instrumentation failure, and revision surgery, which was required in three cases., Conclusions: Although the rib strut grafting technique improves the pseudarthrosis rate, as compared with morsellized graft, it did not affect the maintenance of correction or sagittal alignment. Adjunctive measures to provide truly structural interbody support (fusion cages, allograft rings, two-rod construct) appear to be required to address the shortcomings of anterior single-rod instrumentation.

A retrospective review was performed of 192 newborn hips in 112 patients referred for hip evaluation. The average age at presentation was 12.7 days, with average radiographic follow-up of 15.9 months. Inclusion criteria for our study were a normal physical examination of the hip without evidence of instability and an ultrasound examination that was considered abnormal. Pavlik harness treatment was chosen at the discretion of the treating physician. At final follow-up, dysplasia was defined as greater than two standard deviations above the mean acetabular index (AI) for age. Group I consisted of 43 hips that had Pavlik treatment, and group II consisted of 149 hips that did not receive treatment. There was no difference in these two groups with respect to risk factors for dysplasia or the initial abnormalities seen on ultrasound evaluation, although patients in group I had less coverage of the femoral head during stress maneuvers. No hip in group I and two (1.3%) hips in group II were considered dysplastic (AI > 2 SD) at final radiographic follow-up (p > 0.10). There was no correlation between the severity of the ultrasound abnormality at birth and the subsequent presence of dysplasia (p > 0.10). The two hips considered dysplastic on radiograph were not being actively treated. When the hip examination of a newborn hip younger than 1 month is normal, a screening ultrasound does not appear to predict accurately subsequent hip dysplasia. In this specific setting, an initial screening ultrasound may be too sensitive and does not appear warranted.

The incidence and etiology of back pain during orthotic management of idiopathic scoliosis was determined for 303 patients treated from 1980 through 1990 for a minimum of 1 year. All patients denied back pain before orthotic prescription. Thirty-four (11%) patients reported back pain after institution of brace treatment. A family history of scoliosis (p = 0.014) and vigorous sports activities (p < 0.001) were correlated with pain. Seventeen of 34 patients with pain showed >10 degrees of curve progression during bracing, whereas 67 of 269 patients without pain progressed (p = 0.002). Four patients with pain and 11 without were eventually found to have an underlying pathology (spondylolysis/listhesis). No other underlying pathologies were found. Night pain or a left thoracic curve pattern were not correlated with a serious underlying etiology. Back pain occurring after institution of brace treatment for idiopathic scoliosis is often associated with curve progression and is poorly correlated with a serious underlying pathology.

Twelve patients with healed congenital pseudarthrosis of the tibia underwent gait analysis and muscle strength testing to determine the functional result of treatment. Six children younger than 4 years of age presented with pseudarthroses (early onset), and six children first fractured at older than 4 years of age (delayed onset). Four children with amputations as final treatment for congenital pseudarthrosis were studied for comparison. The early-onset group had undergone an average of 4.2 surgeries and all required transankle fixation. The delayed-onset group had undergone an average of 1.5 surgeries, with one child requiring fixation across the ankle. Lack of ankle push-off and foot drop occurred in the early-onset group. Terminal stance phase ankle power generation was greatly diminished in the early-onset group. Total mechanical work performed by the affected limb, when compared to the uninvolved contralateral limb, was symmetric in delayed-onset patients and reduced by 68% in early-onset patients and by 85% in amputees. Gastrocsoleus strength was reduced by 40%. Gait and muscle strength of patients with "healed" congenital pseudarthrosis of the tibia are markedly disturbed. Early onset of disease, early surgery, and transankle fixation lead to an inefficient gait comparable to that of amputees.

In situ lumbosacral arthrodesis in the treatment of adolescent spondylolisthesis was evaluated in 39 patients. The clinical outcome an average of 4.7 years later was considered excellent or good in 82% of the cases based on their pain and gait. The quality of the fusion mass correlated with outcome. Those patients with the most severe kyphosis (slip angle) had the greatest chance of a poor result. Four patients required reoperation for pseudarthrosis or symptomatic compression of the cauda equina. Three of these were successfully treated with repeat arthrodesis or decompression with sacroplasty or both.

Twenty-three children who had unilateral surgery for idiopathic clubfeet underwent gait analysis and isokinetic muscle-strength testing at an average of 10 years after surgical release. Ankle sagittal-plane kinematics were disturbed in 20 clubfeet. Fifteen children had an internal foot-progression angle. Genu valgum and knee hyperextension were common. Plantarflexion power was decreased by 23% on the side of surgery (p = 0.00005). Quadriceps weakness (defined as a decrease in strength >10% of the nonoperated-on limb's strength) was seen in nine of 22 operated-on limbs and hamstring weakness in eight of 22. Gastrocsoleus weakness exceeded 10% in 16 of 21 clubfeet. Average weakness of the gastrocsoleus was 27% (p < 0.05). Ten-year analysis of children treated with clubfoot releases revealed disturbances in ankle motion and strength. Loss of plantarflexion power and gastrocsoleus strength can be predicted by Achilles tendon lengthening. Knee kinematic abnormalities and weakness also were seen. These abnormalities produce functional difficulties in gait and may lead to degenerative changes later.

Study Design: Three segment (L3-L5) pedicle screw constructs were implanted in caprine spines, and the resulting ankylosis evaluated mechanically and compared 12 weeks after surgery., Objectives: To determine if a construct of maximal stiffness could impair the biologic process of spinal arthrodesis by "stress-shielding.", Summary of Background Data: Fusion mass stiffness is believed to be enhanced by increasing construct stiffness, although previous studies have used semirigid, nonconstrained constructs, which lose stiffness through cyclical loading. Device-related osteoporosis, reported to occur with stiff, constrained implants, may be more related to the presence of fusion induced by the implants rather than the implants themselves., Methods: In 15 goats, L3-L5 segments were instrumented with pedicle screws, and four different diameters of rods (3.2 cm, 4.8 cm, 6.4 mm, and no rods) were implanted as longitudinal connections to vary the stiffness of the constructs. After 12 weeks, animals were killed and the segments were tested to determine their stiffness., Results: In lateral bending, spines "fused" with rods (any size) were significantly stiffer (P = 0.03) than nonrodded spines. There was a trend toward stiffer segments with larger rods (4.8 cm or 6.4 mm) compared with 3.2 mm or no rods. There was a highly significant (P < 0.0001) increase in stiffness of all operated (rodded or nonrodded) segments compared with unoperated controls., Conclusions: The enhancement of segmental stiffness by stiffer constructs was confirmed, suggesting a beneficial effect on spinal arthrodesis by increasing stiffness. Stress shielding could not be shown.

The outcomes of 47 patients, ranging in age from 7 months to 15 years, 8 months (average, 4 years, 8 months) with presumed pyogenic infectious spondylitis (so-called discitis) were evaluated retrospectively with regard to duration and recurrence of symptoms, and the need for readmission, retreatment, or surgical intervention. Among nonimmobilized patients, 18% (four of 22) receiving intravenous antibiotics, 50% (five of 10) receiving oral antibiotics, and 67% (four of six) receiving no antibiotics (analgesics and bed rest only) had either prolonged or recurrent symptoms or both. Among patients treated with spinal immobilization, one of five receiving concomitant intravenous antibiotics and two of two receiving no antibiotics had a recurrence of symptoms following discontinuation of immobilization. Two patients required surgical drainage of paraspinal abscesses (one cervical and one lumbar). These findings support the contention that so-called discitis is simply pyogenic infectious spondylitis in children and suggest that specific treatment with intravenous antibiotics is more likely to lead to rapid relief of symptoms and signs without recurrence.

The bony pathoanatomy of clubfoot has been assessed by a three dimensional reconstruction of transverse CT images obtained from 27 feet in children aged 3-10 years. Principal axes of the bones were determined to quantitate interosseous deformity, while visual inspection of the reconstructed images demonstrated intraosseous deformity. "Medial spin" and midfoot adduction were analyzed on the AP view of the foot ("top" view), while hindfoot pronosupination was analyzed on the AP view of the ankle (posterior view). This technique allows visualization of deformities which normally cannot be analyzed on plain radiographs, and also shows that a variety of interosseous relationships make up the clinical entity known as clubfoot. Abnormal talar pronation ("intorsion") was an unexpected finding of this three dimensional analysis.

In a series of 43 patients diagnosed with congenital anterolateral bowing of the tibia or congenital pseudarthrosis of the tibia treated between 1980 and 1992, the deformities corrected themselves spontaneously in five patients who had no other congenital abnormalities or evidence of neurofibromatosis. At an average follow-up of 58 months (average age at follow-up 80 months), the only residual deformity seen was a limb-length discrepancy in patients with unilateral involvement. In patients with subperiosteal callus formation on the posteromedial concavity of this deformity and an uninvolved fibula, no treatment appears necessary, as this deformity will spontaneously resolve.

The first 14 consecutive patients with idiopathic lumbar scoliosis treated by anterior Texas Scottish Rite Hospital (TSRH) instrumentation are reported. Frontal curve correction averaged 76%, with a 5 degrees (9%) loss of correction in the follow-up period, which averaged 17.6 months (range, 12-29). Spinal balance was improved an average of 1.8 cm toward the center sacral line, and apical vertebral rotation was corrected an average of 49%. Instrumentational kyphosis was minimal, with total L1-S1 lordosis decreasing an average of 1 degree, and no measured compensatory hyperlordosis caudal to the instrumented segment. One hundred percent of disc spaces were radiographically fused by 8 months. There were no neurologic, septic, or implant complications. The contoured solid rod used in this construct provides the same frontal and rotatory correction as previous systems, and minimizes instrumentational kyphosis. Fusion occurs rapidly and reliably because of the stiffness of the construct, which also may eliminate the need for postoperative immobilization.

From January 1982 to December 1987, 114 hips of 80 patients underwent pinning for treatment of slipped capital femoral epiphysis (SCFE). Three groups were differentiated based on the number of pins used. The average length of follow-up was 2 years 5 months. The mean time to physeal closure was 5.43 months in the single pin group, 5.54 months in the two pin group, and 6.44 months in the three or more pin group. These differences were not statistically significant. There was a statistically significant decrease in the rate of pin-related complications and reoperations in the single pin group as compared with the two pin and multiple pin groups. We conclude that central single pin fixation for treatment of SCFE dependably results in physeal closure while minimizing pin-related complications.

The relationship between initial spinal construct stiffness and the stiffness of the resulting fusion mass was studied by performing standardized 10-segment posterior spinal fusions in goats. Animals were divided into 5 groups based on type of spinal construct, using rods of different diameters (3.2 mm, 4.8 mm, 6.4 mm) with or without rigid crosslinking to produce constructs of different stiffnesses. Stiffness data on 28 animals were obtained by removing the spines en bloc, at 6 or 12 weeks postoperatively, and performing load-deformation testing in axial and torsional loading to determine the stiffness of the fusion masses (rods removed). The initial construct stiffnesses were also compared by ex vivo testing on spine specimens to correlate initial construct stiffness with eventual fusion mass stiffness. In axial testing, results showed stiffer fusion masses from larger diameter rod constructs compared with smaller rod constructs. This was similar to results of control testing on spine specimens ex vivo. Rigid crosslinking did not produce stiffer fusions in axial testing, due to a technical limitation of the button-wire implants used to segmentally fix the rods at each vertebra. In torsional testing, stiffer fusion masses resulted from using larger rods, and rigid Crosslinking also produced the stiffest fusion masses, which was consistent with ex vivo testing. In general, larger diameter (stiffer) rods produced stiffer fusion masses, and no evidence of stress shielding was found.

The three-dimensional relationship between acetabulum and femoral head, known as coverage, was evaluated radiographically using a modified inlet view of the pelvis. The relationship of the anterior edge, the center of the femoral head, and the posterior edge of the acetabulum is a straight line (180 degrees) in normal coverage but less in dysplastic hips. This radiographic method provides anatomical information concerning anterior and posterior coverage. Evaluation of 26 hips delineated problems, including possible danger of anterolateral rotation of the acetabulum in the face of posterior deficiency and inadequacy of posterior coverage after Chiari osteotomy.

Nineteen patients with spinal discontinuity syndromes resulting in paralytic spinal deformity were treated with orthoses to postpone spinal stabilization to allow for vertebral growth. All patients had some degree of sensory deficit under the orthosis. The average period of orthotic treatment for all patients was 54 months (range, 22 to 98). The initial upright curve measurement prior to treatment averaged 43 degrees, the best correction obtained during treatment averaged 26 degrees, and all curves averaged 39 degrees when the brace was discontinued or at most recent follow-up. Although pressure sores occurred, no orthosis was abandoned due to a decubitus problem. Eight patients were successfully braced until maturity, at which time they underwent one stage spinal fusion. Five immature patients are still under active orthotic treatment. Poor compliance with brace wear was documented in the cases in which unacceptable progression occurred, requiring spinal fusion prior to maturity. Successful, technically simpler, one stage stabilization procedures were made possible by the successful long-term control of these difficult spinal deformities afforded by orthotic treatment.

Six patients with upper cervical spine ossicles and Down syndrome from a study population of 184 are described. The average age was 20.6 years at the time of diagnosis. Three of the patients were involved in tumbling. Radiographic anatomy of the ossicles and the dens, as well as serial radiographs in three of the six patients, suggest that this represents an avulsion of the upper end of the dens rather than an occipital vertebrae, ossiculum terminale, or os odontoideum, as previously described. The authors advocate restriction of high-risk activities for all patients with Down syndrome.

We studied the applicability of Langenskiöld's classification to a predominantly nonwhite population with infantile tibia vara. Age at presentation was younger than that in previously published studies. Forty-seven tibiae averaging 6 years 7 months of follow-up had 66% good results. Poor results increased in proportion to stage at presentation. Brace treatment for early lesions was only 50% effective. Single tibial osteotomy before 4 years of age gave good results in 85% of tibiae, and multiple osteotomies gave good results between 4 and 8 years of age. One-half of tibiae treated with osteotomy developed recurrent varus. This review documents earlier stages at presentation, a more malignant course, and poorer results than Langenskiöld's series would suggest. We question the accuracy of Langenskiöld's estimate of prognosis when applied to this patient group.

We report five cases of tumors composed primarily of angiomatous and adipose tissue occurring within skeletal muscle in relatively young individuals. Pain is frequently the presenting symptom. The tumors have been described in the literature as angiolipomas, infiltrating angiolipomas, and intramuscular hemangiomas. A discussion of the use of these terms is included. It is our conclusion the term "intramuscular hemangioma" is most appropriate for these lesions.

Five different spinal implants, all using pedicle screw attachment to vertebrae, were examined in a one above/one below corpectomy model, to determine 1) the relative stiffness of each construct, 2) the stresses generated in the implant during loading, and 3) the relative fatigue susceptibility of each implant. Results indicated that the relative axial and torsional stiffnesses were similar for all the implants tested (DKS/Zielke, VSP/Steffee, AO Fixator Interne, Luque plate, AO Notched plate). Hence, each of the devices impart approximately the same stability to the spine in this highly unstable model. Stresses measured at the root of the pedicle screws were found to exceed the endurance limit of stainless steel in those systems in which the pedicle screws were attached rigidly to the plates (VSP/Steffee, AO Fixator Interne). Good agreement was found between the measured stresses and stresses derived from static calculations. Comparisons between the stresses from each implant gave a relative measure of fatigue susceptibility that was validated by in vitro cyclic testing. Implants with stresses exceeding the endurance limit failed during the cyclic test.

This study demonstrates that the broad 4.5 mm dynamic compression plate provides superior stiffness in axial and torsional loading compared to the two anterior rod constructs (Zielke-Slot and Kostuik-Harrington) and the thinner ASIF T-plate in this ex-vivo testing. The Armstrong National Research Council (NRC) plate, designed specifically for anterior spinal instrumentation, has essentially the same mechanical performance characteristics as the broad dynamic compression plate. When placed on the lateral aspect of the vertebral body, these latter two plates lie well away from the anterior vascular structures. Screws are placed slightly off set in the plate, two each in the vertebral bodies immediately above and below the fracture, the screws directed transversely across the vertebral body. The broad DCP plate is easily contoured and implanted, and will allow 1.8 mm of compression to be applied to a strut graft between vertebral bodies. Anterior surgery for the treatment of burst fractures with retropulsed bone provides a means for direct decompression of the spinal canal. With an appropriate implant, additional advantages include instrumentation over a shorter distance (one above and one below the fracture) and no need for further operative procedures to implant or remove posterior implants. Due to their superior stiffness in axial and torsional load, the broad dynamic compression plate and the Armstrong NRC plate appear to fulfill most nearly the ideal attributes of an anterior spinal implant for the treatment of burst fractures of the throacic and lumbar spine.

Three patients with birth fractures and Werdnig-Hoffmann disease are presented. Two of the three were erroneously diagnosed as having osteogenesis imperfecta. The etiology of these fractures appears to be in utero osteoporosis secondary to decreased movement, leading to pathologic fracture during birth. Immobilization led to uneventful healing in all cases; no recurrent fractures were seen.

Mechanical testing protocols and test methods used to evaluate spinal implants have varied widely. Use of different test methods would not present a problem except that multicomponent mechanical systems, such as the spine and spinal implant constructs, yield different mechanical properties when subjected to different test methods. The goal of this article is to outline considerations specific to the mechanical assessment of spinal implants. With standard test methods and treatment of results, redundancy between testing programs will be reduced and comparison of results will be facilitated.

Physeal bridge resection and osteotomy were used in the treatment of three cases of Stage VI Blount disease. At follow-up, all patients showed continued growth of the proximal tibial physis, as well as maintenance of alignment. Bridge resection with realignment osteotomy offers an attractive alternative in the treatment of skeletally immature patients with Blount disease and a medial physeal bridge.