What Is the Cost of a "Cast Holiday" in Treating Children With Early Onset Scoliosis (EOS) With Elongation Derotation Flexion (EDF, "Mehta") Casting?

INTRODUCTION: Serial casting of children with early onset scoliosis (EOS) is an established treatment option. A break from cast treatment often called a "cast holiday," (CH) is often allowed by some centers, particularly over the summer months. The impact of CHs on treatment duration or outcome has not been examined. METHODS: Institution review board approved retrospective review of children treated for EOS with elongation derotation flexion ("Mehta") casting at a children's hospital between 2001 and 2016 with a minimum of 2 years' follow-up. A CH was defined as a minimum of 4 weeks out of the cast, braced, or unbraced.The analysis was performed to determine the impact of a CH within the first 18 months of treatment. Separate analyses were performed for the entire cohort of children castedduring the study period, and then separately looking at idiopathic EOS in isolation. The impact of a CH was assessed in terms of the likelihood of achieving scoliosis <15 degrees at the final follow-up ("success"). Odds ratios were used to assess group differences between "success" ratios, and Student t tests assessed group differences for parametric data. RESULTS: Ninety children met inclusion and exclusion criteria, 31 of whom took a CH during the first 18 months of treatment (34%). This included 59 patients with idiopathic EOS (66%), 18 with syndromic EOS, 5 congenital, and 1 neuromuscular. There were no statistically significant differences between CH and no CH groups.Forty-four percent of the no CH group achieved scoliosis <15 degrees at final follow-up, as opposed to 13% of the CH group, an odds ratio of 5.3 for success without a CH. When limited to children with idiopathic EOS, 56% achieved success in the no CH, versus only 22% in the group that took a CH, an odds ratio of 4.4 for success with no CH. CONCLUSION: This study demonstrates that children treated for EOS with serial casting who take a CH within the first 18 months of treatment are less likely to achieve scoliosis <15 degrees than those who persist with treatment. LEVEL OF EVIDENCE: Level III.

Prevalence of Hip Dysplasia and Associated Conditions in Children Treated for Idiopathic Early-onset Scoliosis-Don't Just Look at the Spine.

BACKGROUND: Hip dysplasia, congenital muscular torticollis, plagiocephaly, and metatarsus adductus are known to be associated. The etiology of infantile idiopathic scoliosis and its association with the aforementioned conditions is unknown. This study reviews a series of infantile scoliosis patients to address this gap. METHODS: The medical records of all patients treated with casting for early-onset scoliosis (EOS) from 2001 to 2016 were retrospectively reviewed. Inclusion criteria were a diagnosis of idiopathic EOS and age below 4 years at the time of the first cast. Demographic information, comorbid conditions, and radiographic measurements including Cobb angle and acetabular index (AI) were collected. The first acceptable anteroposterior pelvis radiograph for each patient was measured. An AI≥30 degrees was defined as hip dysplasia. A measurement between 25 and 30 degrees was defined as a "hip at risk." RESULTS: Between 2001 and 2016, 142 patients were treated with casting. Eighty-one patients met the inclusion criteria. The mean age at the first cast was 19.3 (±7.5) months and the mean Cobb angle was 53.6 (±18.8) degrees. There was no significant correlation between Cobb angle and AI. Nine patients met radiographic criteria for hip dysplasia (11.1%), only 4 of whom had been previously diagnosed. Thirty-six patients (44.4%) met the criteria of having at least 1 hip "at risk" of hip dysplasia. Ten patients (12.3%) had been diagnosed with torticollis and 13 patients (16.0%) with plagiocephaly. Three patients (3.7%) had been diagnosed with metatarsus adductus or clubfoot. In total, 30.9% of patients (25/81) had at least one of the above comorbid conditions. CONCLUSIONS: In a large group of children treated for idiopathic EOS, we found a high prevalence of commonly associated conditions-hip dysplasia, torticollis, plagiocephaly, metatarsus adductus, and clubfoot. In 6.2% of our sample, a diagnosis of hip dysplasia was not made in a timely manner despite routine radiographic spine follow-up. With increasing subspecialization within pediatric orthopaedics, surgeons need to maintain vigilance in assessing the entire child. LEVEL OF EVIDENCE: Level IV.

Minimum 5-Year Follow-up of Mehta Casting to Treat Idiopathic Early-Onset Scoliosis.

BACKGROUND: With the exception of Mehta's 2005 report on her experience treating early-onset scoliosis with serial casting, all subsequent studies have had limited follow-up. This current study sought to assess the results of serial casting at a minimum 5-year follow-up and to identify the predictors of the sustained resolution of scoliosis. METHODS: This study is a retrospective review of children treated for idiopathic early-onset scoliosis with serial casting at a children's hospital between 2001 and 2013 with a minimum 5-year follow-up. A Cobb angle of ≤15° and a decrease in the Cobb angle of >20° at the most recent follow-up were separately assessed. The differences between groups based on these criteria were tested with Student t tests with alpha = 0.05. RESULTS: Fifty-four children were treated during the study period; of these, 38 had at least 5 years of follow-up and comprised the study sample. The mean follow-up (and standard deviation) was 8 ± 2 years (range, 5 to 13 years). The mean patient age at the time of the first cast was 24 ± 15.1 months (range, 9 to 63 months), with a mean Cobb angle of 56.2° ± 20.1° (range, 22° to 109°). Forty-nine percent of children had scoliosis of ≤15° at the time of the most recent follow-up, and 73% of children were improved by at least 20°. Children with ≤15° scoliosis, compared with children with >15° scoliosis, had significantly lower initial Cobb angle (48.2° compared with 63.7°; p = 0.016), supine traction Cobb angle (22.5° compared with 33.2°; p = 0.048), first-in-cast Cobb angle (24.1° compared with 37.6°; p = 0.01), and first-in-cast rib-vertebral angle difference (12.8° compared with 26.2°; p < 0.01). Age at the time of the first cast, initial rib-vertebral angle difference, flexibility, and body mass index were not significantly different (p > 0.05) between the groups. Three children who initially achieved scoliosis of ≤15° after casting substantially relapsed. CONCLUSIONS: At a minimum follow-up of 5 years, the initial Cobb angle, first-cast Cobb angle, rib-vertebral angle difference, and traction Cobb angle were all predictive of sustained scoliosis of ≤15°. However, with continued growth, relapse of scoliosis was seen in 3 patients. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Optimization of Casting in Early-onset Scoliosis.

BACKGROUND: Early-onset scoliosis is a spine deformity that presents before the age of 3 years. When compared with age-matched controls, children with the condition are known to be at risk for significant morbidity and mortality. Although many works support the use of casting for this condition, the key technical factors to optimize the outcomes of casting are not clear. This work was designed to evaluate the role of frequency of radiographic imaging and over the shoulder straps in the outcomes of casting. METHODS: Two surgeons at 2 centers followed nearly identical protocols for applying casts for early-onset scoliosis. At center A, the surgeon hoped to improve outcomes by obtaining radiographs after each cast and by reinforcing the cast with shoulder straps. At center B, the surgeon did not use shoulder straps and limited radiographs to once every 6 months. Children were included if they were 3 years or below of age and had a curve of ≥50 degrees at the time of the first cast and had a minimum of 3 years of follow-up. Center was used as a variable in a multivariable regression that also included: age at first cast, initial curve magnitude, and presence of a syrinx or genetic syndrome with the outcome of curve resolution. RESULTS: There were 40 children at center A, 9 of whom experienced resolution of their scoliosis. There were 36 children at center B, and 11 demonstrated scoliosis resolution. At center A, 2 of 10 children with a syrinx or genetic syndrome demonstrated curve resolution while 7 of 30 without these comorbidities did. At center B 3 of 10 children with a syrinx or genetic syndrome had curve resolution while 8 of 26 children without these comorbidities did. CONCLUSIONS: The children in group A demonstrated results very similar to the children of group B. Thus, the extra burden of shoulder straps and frequent radiographs are unnecessary. LEVEL OF EVIDENCE: Level III.

Initial Cast Correction as a Predictor of Treatment Outcome Success for Infantile Idiopathic Scoliosis.

BACKGROUND: Cast treatment for infantile idiopathic scoliosis patients ultimately corrects deformity in varying amounts. As the reasons for these differential outcomes are not fully elucidated, the aim of this study was to identify clinical and radiographic variables correlated with better cast correction. METHODS: Patients in the Children's Spine Study Group and Growing Spine Study Group registries who underwent cast treatment for idiopathic scoliosis between 2005 and 2013 with 1-year minimum follow-up were included. Data including major curve and rib-vertebra angle difference before cast, initial in-cast application, after cast treatment, and at most recent follow-up were collected. Univariable and multivariable regression analyses were used to identify factors associated with lower major curves at most recent follow-up. RESULTS: A total of 68 patients were identified and followed for a mean of 2.5 (range, 1.1 to 5.4) years after cast treatment. Cast treatment lasted an average of 16.7 months, with a median of 6 cast applications (range, 2 to 19). Twenty-five subjects (37%) had a most recent major curve <15 degrees (success), whereas 43 had a curve that was >15 degrees (unresolved). Multivariable linear regression determined that younger age (P=0.02), smaller precast major curve (P<0.001), and greater percent major curve correction in initial cast (P=0.006) were associated with smaller major curve at most recent follow-up. Multivariable logistic regression determined that success patients were younger than unresolved patients (average age, 1.4 vs. 2.1 y; P=0.003), and had smaller in-cast major curves after initial cast application (average, 18 vs. 27 degrees; P=0.002). CONCLUSIONS: Infantile idiopathic scoliosis patients casted at an earlier age, with smaller major curves, and greater percent major curve correction in initial cast have the best prognosis. Patients' percent major curve correction, which may represent curve flexibility and/or cast quality, is a predictor of treatment success when age and precast major curve are also taken into account. LEVEL OF EVIDENCE: Level III-retrospective study.

Spontaneous Fatal Intraoperative Rupture of Great Vessel During Growing Rod Lengthening: Do Children With Ehlers-Danlos Syndrome Require the Availability of Vascular Expertise? A Case Report and Review of the Literature.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is a family of inherited connective tissue diseases. Kyphoscoliotic EDS (kEDS) is associated with severe and early spinal deformity. Very little has been reported regarding the orthopaedic surgical care of kEDS likely due to its rare incidence. A more common subtype is the vascular-type EDS (vEDS, previously labeled type IV), which is associated with reports of vascular complications in the literature. METHODS: The case report of a single, fatal complication of spontaneous rupture of the superior vena cava, after extubation, subsequent to revision minimal growing rod lengthening in a child with kEDS. We additionally review prior reported cases of kEDS for pediatric spine surgery and the sentinel event of spontaneous vascular rupture in all EDS patients. RESULTS: The anterior thoracoabdominal approach in children with kEDS has been associated with severe intravascular complications, with no deaths reported to date. Posterior spinal procedures were associated with frequent overall complications, but no events of perioperative or spontaneous vascular injury were identified before our case.Reports of spontaneous vessel rupture (n=39) appear more frequently in vEDS, but have been documented in patients with EDS type I (classic EDS or cEDS) and kEDS disease. The 30-day mortality in these patients was 59%. The majority of the deaths occurred on the day of the vascular event. Surviving patients overwhelmingly received intraoperative consultation and treatment from either general or vascular surgeons at their respective institutions for assistance. CONCLUSIONS: Providers should consider their proximity to available emergent consultation before operating on patients with EDS of any subtype. LEVEL OF EVIDENCE: Level V-expert opinion.

Utilization and efficacy of computational gait analysis for hamstring lengthening surgery.

A retrospective analysis of computational gait studies performed in a single lab over a 12 year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 Subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome.

Kinematics and kinetics of normal and planovalgus feet during walking.

Planovalgus deformity is prevalent in cerebral palsy patients, but very few studies have quantitatively reported differences between planovalgus and normal foot function. Intersegmental foot kinetics have not been reported in this population. In this study, a three segment (hindfoot, forefoot, hallux) kinematic and kinetic model was applied to typically developing (n=10 subjects, 20 feet) and planovalgus (n=10 subjects, 18 feet) pediatric subjects by two clinicians for each subject. Intra-clinician and inter-clinician repeatability of kinematic variables have been previously reported. Variability of kinetic outcomes (joint moments and power) is reported and found to be equally repeatable in typically developing and planovalgus groups. Kinematic differences in the planovalgus foot including excessive ankle eversion (valgus) and plantarflexion, reduced ankle flexion range of motion, and increased midfoot joint dorsiflexion and pronation reflected the reported pathology. Contrary to clinical expectations no significant difference was observed in midfoot flexion or ankle eversion ranges of motion. Kinetic differences in planovalgus feet compared to typically developing feet included reduced ankle plantarflexion moment, ankle power and midfoot joint power.

A multi-segment foot model based on anatomically registered technical coordinate systems: method repeatability and sensitivity in pediatric planovalgus feet.

Several multisegment foot models have been proposed and some have been used to study foot pathologies. These models have been tested and validated on typically developed populations; however application of such models to feet with significant deformities presents an additional set of challenges. For the first time, in this study, a multisegment foot model is tested for repeatability in a population of children with symptomatic abnormal feet. The results from this population are compared to the same metrics collected from an age matched (8-14 years) typically developing population. The modified Shriners Hospitals for Children, Greenville (mSHCG) foot model was applied to ten typically developing children and eleven children with planovalgus feet by two clinicians. Five subjects in each group were retested by both clinicians after 4-6 weeks. Both intra-clinician and inter-clinician repeatability were evaluated using static and dynamic measures. A plaster mold method was used to quantify variability arising from marker placement error. Dynamic variability was measured by examining trial differences from the same subjects when multiple clinicians carried out the data collection multiple times. For hindfoot and forefoot angles, static and dynamic variability in both groups was found to be less than 4° and 6° respectively. The mSHCG model strategy of minimal reliance on anatomical markers for dynamic measures and inherent flexibility enabled by separate anatomical and technical coordinate systems resulted in a model equally repeatable in typically developing and planovalgus populations.

Lower extremity strength and hopping and jumping ground reaction forces in children with neurofibromatosis type 1.

The purpose of this study was to (1) extend the research findings of decreased muscular force production in grip strength to the lower extremity strength of children with NF1 and (2) to determine if there was a relationship between isometric strength and functional activities in children with NF1. Force production was assessed using a hand held dynamometer (HHD) and a functional task (hopping and jumping) on a force plate. Data from twenty-six children with NF1 were compared to data from 48 typically developing children of similar sex, weight and height. Children with NF1 demonstrated statistically significant lower force production with HHD (p<0.01) during hip extension, but similar force production for knee extension and ankle plantar flexion compared to the control group. A relationship existed between the ground reaction forces at take-off from both hopping and jumping and the force generated from knee extensor strength in the NF1 group. The addition of a functional task to hand held dynamometry is useful for determining a relationship between common clinical measures and functional activities.

Functional decline in children undergoing selective dorsal rhizotomy after age 10.

AIM: To compare function and gait in a group of children older than most children who received selective dorsal rhizotomy (SDR) with age- and function-matched peers who received either orthopedic surgery or no surgical intervention. METHOD: A retrospective study examined ambulatory children with diplegic cerebral palsy, aged between 10 years and 20 years and categorized in Gross Motor Function Classification System (GMFCS) levels I or II. Three groups were considered: (1) children who had selective dorsal rhizotomy (n=8; two females, six males; mean age 15y 4mo at SDR, 16y 8mo at follow-up); (2) children who had orthopedic surgery (n=9; three females, six males; mean age 14y 6mo at SDR, 15y 1mo at follow-up), and (3) children who had no surgical intervention (n=9; two females, seven males; mean age 15y 6mo at follow-up). Longitudinal measures of gait analysis (velocity, gait deviation index, and gait variable scores) and gross motor function (GMFCS level, Gross Motor Function Measure scores, and centiles) were examined. RESULTS: No significant differences were found between changes in gait comparing rhizotomy with orthopedic surgery; however, the group who received orthopedic surgery demonstrated improved gait compared with the group without surgical intervention. Longitudinal comparisons of gross motor function demonstrated a decrease in the group who received SDR. Between-group analysis of outcomes also demonstrated worse outcomes of the SDR group compared with the orthopedic surgery group and with the no surgical intervention group. INTERPRETATION: Rhizotomy in older children was associated with functional declines compared with similar children who had no surgery and with those who underwent orthopedic surgery. This suggests that age greater than 10 years might be a contraindication for SDR if the goal is to improve motor skills.

Pediatric 25-hydroxyvitamin D concentrations in neurofibromatosis type 1.

OBJECTIVE: Low 25-hydroxyvitamin D (25OHD) concentrations have been associated with tumors and osteopenia or fractures in adults with neurofibromatosis type 1 (NF1). We report 25OHD concentrations in 109 children with NF1 and 218 controls matched for age, sex, geographic location, and time of year. METHODS: Children with NF1 were recruited (n=109; 2-17 years), and clinical data and dual-energy X-ray absorptiometry measurements were obtained. 25OHD concentrations were measured in subjects and controls. RESULTS: More NF1 individuals (50%) were in the 25OHD insufficient or deficient range (<30 ng/mL) (1 ng/mL = 2.496 nmol/L) compared to controls (36%) (p = 0.0129). 25OHD concentrations were higher in individuals with neurofibromas after controlling for age (p = 0.0393), and were negatively associated with whole-body subtotal bone mineral density (BMD) z-scores (p = 0.0385). CONCLUSIONS: More children with NF1 had 25OHD concentrations <30 ng/mL, potentially because of increased pigmentation and/or decreased sunlight exposure. In contrast to adults, decreased 25OHD concentrations were not associated with neurofibromas, and there was no positive association between 25OHD and BMD.

Motor proficiency in children with neurofibromatosis type 1.

PURPOSE: Neurofibromatosis type 1 (NF1) is a genetic disorder with associated musculoskeletal abnormalities, tumors, and developmental delays. The purpose of this study was to investigate and characterize the motor proficiency of children with NF1. METHODS: Children with NF1 were assessed using the Bruininks-Oseretsky Test (BOT 2) instrument. The NF1 group scores were compared with age and sex-matched test norms. RESULTS: Twenty-six children participated in the study. The NF1 group had statistically significant lower scores (P < .05) for the total motor composite (Z = -1.62) and 7 of the 8 subtests. Nineteen percent (n = 5) scored in the average category, 54% (n = 14) scored in the below-average category, and 27% (n = 7) scored in the well-below-average category. CONCLUSIONS: Children with NF1 have significantly lower motor proficiency than the BOT 2 normative scores. The results indicate the BOT 2 is useful in identifying and characterizing delays in motor proficiency for children with NF1.

Orthopaedic manifestations of Navajo familial neurogenic arthropathy.

BACKGROUND: Navajo Familial Neurogenic Arthropathy is a disease identified in Navajo children, primarily residing in Arizona, New Mexico, and Utah. To date, there are no reports in the orthopaedic literature regarding this disorder, particularly the clinical manifestations and treatment considerations. METHODS: We carried out a retrospective chart and radiographic review of 2 patients with Navajo familial neurogenic arthropathy. We present these 2 patients as representative of the orthopaedic manifestations of Navajo familial neurogenic arthropathy. RESULTS: Both patients have significant axial and appendicular bone abnormalities, Charcot-type arthopathy, heat intolerance and also anhidrosis. They have normal intelligence. Both patients underwent surgical interventions, with recurrent deformity and infection being the most common complications. CONCLUSIONS: Navajo familial neurogenic arthropathy is a rare clinical entity, seen most commonly in the southwestern regions of the United States. Patients are found to have a myriad of orthopaedic abnormalities, and surgical intervention, while sometimes indicated, can be fraught with complications. LEVEL OF EVIDENCE: Level IV, case series.

Analysis of radiographic characteristics of anterolateral bowing of the leg before fracture in neurofibromatosis type 1.

BACKGROUND: Anterolateral leg bowing is associated with neurofibromatosis type 1 (NF1) frequently leading to fracture and nonunion of the tibia. The objective of the study was to characterize the radiographic findings of tibial dysplasia in NF1. METHODS: This study is a retrospective review of radiographs of tibial dysplasia obtained within 52 years, between 1950 and 2002, from the Shriners Hospitals for Children, Salt Lake City, and of peripheral quantitative computed tomographic images of 3 individuals with anterolateral bowing of the leg without fracture compared with age- and sex-matched controls. RESULTS: Individuals with NF1 with bowing of the leg have the appearance of thicker cortices with medullary narrowing on plain film radiographs. The peripheral quantitative computed tomographic images of individuals with NF1 with anterolateral bowing show an unusual configuration of the tibia. CONCLUSIONS: Anterolateral bowing of the leg in NF1 is associated with the appearance of thicker cortices with medullary narrowing rather than thinning of the long bone cortex on plain film radiographs as currently used as a qualifier in the sixth diagnostic criterion for the clinical diagnosis of NF1. Individuals with NF1 who have anterolateral bowing of the leg have differences in tibial geometry compared with age- and sex-matched controls. CLINICAL RELEVANCE: The characterization of the radiographic findings of long bone bowing in NF1 helps clarify the NF1 clinical diagnostic criteria.

Evidence of increased bone resorption in neurofibromatosis type 1 using urinary pyridinium crosslink analysis.

Although neurofibromatosis type 1 (NF1) is a neurocutaneous disorder, skeletal abnormalities such as long-bone dysplasia, scoliosis, sphenoid wing dysplasia, and osteopenia are observed. To investigate the role of bone resorption as a mechanism for the bony abnormalities, we selected urinary pyridinium crosslinks (collagen degradation products excreted in urine) as a measure of bone resorption in NF1. Bone resorption was evaluated by quantitative assessment of the urinary excretion of pyridinium crosslinks [pyridinoline (Pyd) and deoxypyridinoline (Dpd)]. Total (free plus peptide-bound) pyridinium crosslinks from the first morning urines from 59 NF1 children (ages 5-19) were extracted and analyzed (17 children with a localized skeletal dysplasia, and 42 without). The data were compared with a healthy reference population without NF1 (n = 99). Multivariate analyses, controlling for age showed statistically significant increases for Dpd (p < 0.001) and the Dpd/Pyd ratio (p < 0.001) in NF1 individuals with and without a skeletal dysplasia. NF1 children have an increase in the urinary excretion of pyridinium crosslinks, reflecting increased bone resorption. The effects of NF1 haploinsufficiency likely contribute to abnormal bone remodeling, either directly or indirectly by aberrant Ras signaling, potentially predisposing NF1 individuals to localized skeletal defects.

Casting and traction treatment methods for scoliosis.

There is little consensus among spinal deformity surgeons as to the best way to treat infantile or early-onset scoliosis. Bracing may or may not be effective, and subcutaneous rods have a high complication rate. Current techniques of casting as championed by Min Mehta and Jean Dubousset are presented as is the use of halo-gravity traction for the more severe cases. We firmly believe that "outdated" techniques, such as casting and traction, still play an important role in the treatment of this challenging problem.

Double inactivation of NF1 in tibial pseudarthrosis.

Osseous abnormalities, including long-bone dysplasia with pseudarthrosis (PA), are associated with neurofibromatosis type 1 (NF1). Prospectively acquired tissue from the PA site of two individuals with NF1 was used for immunohistochemical characterization and genotype analysis of the NF1 locus. Typical immunohistochemical features of neurofibroma were not observed. Genotype analysis of PA tissue with use of four genetic markers (D17S1863, GXALU, IN38, and 3NF1-1) spanning the NF1 locus demonstrated loss of heterozygosity. These results are the first to document double inactivation of NF1 in PA tissue and suggest that the neurofibromin-Ras signal transduction pathway is involved in this bone dysplasia in NF1.

Superficial versus deep transfer of the posterior tibialis tendon.

Transfer of the posterior tibialis tendon to the dorsum of the foot is a commonly performed procedure in conditions that weaken ankle dorsiflexors and evertors, resulting in equinovarus foot deformities. When transferring the tendon, surgeons have the choice of routing the tendon deep to the extensor retinaculum or superficial to it. This study compares the biomechanics of these two routing methods. Seven cadaveric lower limbs were tested by applying known forces to the transferred posterior tibialis tendon. Resultant kinematics indicated that passing superficial to the retinaculum resulted in a significantly more efficient motion than transfer deep to the retinaculum.

Measurement of spinal kyphosis: implications for the management of Scheuermann's kyphosis.

STUDY DESIGN: Repeat clinical radiograph measurement of kyphosis was performed. OBJECTIVES: To evaluate precision in kyphosis measurement, the presence of intra- and interobserver error, and the effect of endplate selection and curve magnitude on error. SUMMARY OF BACKGROUND DATA: One study thus far has shown no interobserver difference in readings and an error interval of +/-11 degrees. METHODS: Four experienced examiners measured 30 radiographs of varying angles of kyphosis without preselected end vertebrae twice using the Cobb method. RESULTS: The mean intraobserver variance was 4.3 degrees (95% confidence interval, +/-9.6 degrees). One examiner had significantly better precision (P= 0.02) than the other examiners, who had no significant difference among them (P = 0.41). This examiner's mean intraobserver difference was 2.3 degrees (95% confidence limit, +/-6.2 degrees ). The 95% confidence limit for the interobserver difference was +/-8.7 degrees. The vertebral error index did not have a rank correlation with precision between readings. Magnitude of curve did not correlate with variance in measurement. CONCLUSIONS: The broad range in intra- and interobserver differences in the measurement of kyphosis should be taken into account in making management decisions or evaluating the success or failure of a treatment program. Careful technique in measurement may allow for improvement in individual precision.