Morphologic discrimination among healthy subjects and patients with progressive and nonprogressive adolescent idiopathic scoliosis

Skill level and the free moment during a pistol aiming task

The present study investigated the transversal rotation of body and its relation to the horizontal movement for expert shooters and novices in a pistol aiming task. Participants stood on a force plate with an air pistol and aimed it to the centre of a target, positioned 1.4 m above the floor and 10 m away from the force plate, for 30 s as accurately as possible. The results revealed that the novice group showed greater transversal body variability represented by the free moment (FM) than the expert group. Correlation analysis showed that there is tight coupling between the FM and centre of pressure both in the anterior-posterior and medio-lateral directions for the expert group while only strong coupling of that in the anterior-posterior direction for the novice group. The findings suggest that FM is a critical factor to accurately aim the pistol on the target and there is a different postural strategy, in terms of the body motion in the transversal and horizontal space, as a function of skill level to realise success in the pistol aiming task.

Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST): Development and Validation of a Prognostic Model in Untreated Adolescent Idiopathic Scoliosis Using the Simplified Skeletal Maturity System

STUDY DESIGN

Prognostic study and validation using prospective clinical trial data.

OBJECTIVE

To derive and validate a model predicting curve progression to ≥45° before skeletal maturity in untreated patients with adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Studies have linked the natural history of AIS with characteristics such as sex, skeletal maturity, curve magnitude, and pattern. The Simplified Skeletal Maturity Scoring System may be of particular prognostic utility for the study of curve progression. The reliability of the system has been addressed; however, its value as a prognostic marker for the outcomes of AIS has not. The BrAIST trial followed a sample of untreated AIS patients from enrollment to skeletal maturity, providing a rare source of prospective data for prognostic modeling.

METHODS

The development sample included 115 untreated BrAIST participants. Logistic regression was used to predict curve progression to ≥45° (or surgery) before skeletal maturity. Predictors included the Cobb angle, age, sex, curve type, triradiate cartilage, and skeletal maturity stage (SMS). Internal and external validity was evaluated using jackknifed samples of the BrAIST data set and an independent cohort (n = 152). Indices of discrimination and calibration were estimated. A risk classification was created and the accuracy evaluated via the positive (PPV) and negative predictive values (NPV).

RESULTS

The final model included the SMS, Cobb angle, and curve type. The model demonstrated strong discrimination (c-statistics 0.89-0.91) and calibration in all data sets. The classification system resulted in PPVs of 0.71-0.72 and NPVs of 0.85-0.93.

CONCLUSIONS

This study provides the first rigorously validated model predicting a short-term outcome of untreated AIS. The resultant estimates can serve two important functions: 1) setting benchmarks for comparative effectiveness studies and 2) most importantly, providing clinicians and families with individual risk estimates to guide treatment decisions.

LEVEL OF EVIDENCE

Level 1, prognostic.

Body composition in males with adolescent idiopathic scoliosis: a case-control study with dual-energy X-ray absorptiometry

Background

In contrast to the well-characterized body growth and development of females with adolescent idiopathic scoliosis (AIS), the pubertal growth pattern of male patients has not been well-documented. Recently, significantly lower body weight (BW) and body mass index (BMI) were reported in males with AIS, and were thought to be related to curve progression. A case–control study was carried out to characterize the body composition and bone status of males with AIS, with the aim of gaining a better understanding of lower BW among these patients.

Methods

Forty-seven males with AIS and forty age- and gender-matched healthy controls were recruited. Standing height (SH) and BW were measured. The SH of the males who had AIS was corrected using Bjure’s equation, and then the BMI was calculated. Body composition, including subcranial fat mass (FM), lean mass (LM), and bone mineral content (BMC), and bone mineral density (BMD) were analyzed using dual-energy X-ray absorptiometry. The LM index (LMi) and the FM index (FMi) were calculated by dividing the FM and LM by the square of the SH. Logistic regression analysis was employed for comparison between AIS and controls.

Results

The AIS patients had comparable age and Tanner staging for pubic hair as the controls. After adjustment for age, the AIS patients showed comparable SH but significantly lower BW and BMI than that of the controls. The LM, LMi, BMC and BMD were also significantly lower in the AIS patients than in the controls. However, the difference in BMC between two groups was not significant by adjusting for age, FM and LM.

Conclusion

The male AIS patients showed abnormal body composition, presenting as significantly lower LM than the controls. The lower BMC observed in the patients might due to the abnormal body composition.

Obesity negatively affects spinal surgery in idiopathic scoliosis

BACKGROUND

Are obese patients with idiopathic scoliosis undergoing spinal surgery at higher risk for perioperative complications? This is not clearly understood. One previous study showed a greater preoperative thoracic kyphosis but no increase in perioperative complications.

QUESTIONS/PURPOSES

We asked whether obese adolescents with idiopathic scoliosis have more perioperative complications and decreased curve correction.

METHODS

We retrospectively reviewed 478 patients with idiopathic scoliosis operated on from 1998 to 2010. There were 236 (187 females, 49 males) with a mean age of 14 years (range, 11-22 years) who met the inclusion criteria. Demographic data, radiographic measurements, perioperative data, and major and minor complications were recorded. The BMI percentile (BMI%) defined two patient groups: healthy weight (BMI%<85) (n=181) and obese (BMI%≥85) (n=55). The preoperative curves were similar in the two groups. Minimum followup was 2 years (mean, 6 years; range, 2-14 years).

RESULTS

Postoperatively, the mean major curve was smaller for healthy-weight patients (20°; range, 8°-36°) than for obese patients (23.2°; range, 12°-56°), as was the mean kyphosis (31.1° [range, 10°-56°]) versus 36° [range, 15°-33°], respectively). The postoperative lordosis was similar in both groups. Increased BMI% correlated with increased operative time, intraoperative blood loss, amount of intraoperative crystalloids, and difficulty with administration of spinal anesthesia.

CONCLUSIONS

Obese patients are at higher risk for perioperative complications when undergoing spinal deformity surgery. Counseling should be done with the patient and family and weight loss recommended before surgery.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Instructions for Authors for a complete description of levels of evidence.

Anthropometry and body composition profile of girls with nonsurgically treated adolescent idiopathic scoliosis

STUDY DESIGN

Cross-sectional study with level III of evidence.

OBJECTIVE

To describe different anthropometric and body composition parameters of adolescent girls with adolescent idiopathic scoliosis (AIS), comparing them with the standards of a healthy age-matched population.

SUMMARY OF BACKGROUND DATA

Body growth and development of adolescent girls with AIS seems to differ from the healthy subjects, especially at perpubertal stages. Young scoliotic adults have been found to be taller, lighter, and thinner than age-matched healthy population. Body composition profile taken from measurements of skin-fold thickness, bony diameters at different levels, and arm and legs perimeters has not been previously reported in AIS patients.

METHODS

A nonconsecutive series of 52 AIS girls (mean age: 13.9 years) with an average scoliotic curve of 27° Cobb (range: 20-58) underwent an anthropometric study. None of the AIS girls had been treated previously with spinal surgery. The control group consisted of 92 girls without spine deformity, matched in age (mean: 13.8 years). Weight, height, and skin-fold thickness in millimeters at six levels were measured. Body mass index (BMI), Ponderal index, percentage of body fat, percentage of muscular tissue, fat mass, lean body mass, muscular weight, bony weight, and residual weight were calculated using standard rules to estimate body composition. The somatotype components (endomorphy, mesomorphy, and ectomorphy) were calculated according to the Carter equations. RESULTS.: Compared with the control population, scoliotic girls had a significantly lower mean weight (51.4 ± 10.2 kg vs. 54.7 ± 8.1 kg; P < 0,05), a lower BMI (20.1 ± 3.4 vs. 21.4 ± 2.4; P < 0.001), and a higher Ponderal index (43.2 ± 2.4 vs. 42.2 ± 1.6; P < 0.01). Girls with AIS showed a progressive decrease of the BMI as the age increased. The percentage of body fat was also lower in scoliotic girls, without significant statistical differences (14.1 ± 3.8 vs. 15 ± 3.6). Out of the 52 AIS girls, 11 (21.2%) showed a BMI below 17.5, which has been considered the limit for anorexia. In the control group, only 3 of 92 girls (3.3%) had BMI below that level. The somatotype differed also between scoliotics and controls: higher in the ectomorphic component (3.29 ± 1.68 vs. 2.40 ± 1.11; P < 0.001), and lower in the mesomorphic component (2.86 ± 0.82 vs. 3.70 ± 1.11; P < 0.01) in AIS patients.

CONCLUSION

The differences in some anthropometric parameters (weight, IMC, IP) and in the somatotype suggest that the idiopathic scoliosis not only disturbs normal spine growth but also seems to have implications on the whole corporal development. Whether these changes could be related to abnormal spinal growth or subsequent to nutritional changes in AIS still remains uncertain. Presumably, some endocrine factors affecting body composition and growth might be involved in the etiology of idiopathic scoliosis.

Adolescent idiopathic scoliosis in athletes: is there a connection?

The potential relationship between adolescent idiopathic scoliosis (AIS) and sports is rather vague. Sports have often been considered to be a causative factor of, or a treatment option for the former, particularly among adolescent athletes who are engaged in certain athletic activities. The highly repetitive nature of sports, amenorrhea, exercise-related exerted stress on the immature spine of professional adolescent athletes, and the joint laxity that may coexist during adolescence, have also been associated with an increased incidence of AIS. The purpose of this article is to discuss the potential connection between sports and AIS by reviewing the existing literature.

Aetiology of idiopathic scoliosis: current concepts

The aetiology of the three-dimensional spinal deformity of idiopathic scoliosis (IS) is unknown. Progressive adolescent idiopathic scoliosis (AIS) that mainly affects girls is generally attributed to relative anterior spinal overgrowth from a mechanical mechanism (torsion) during the adolescent growth spurt. Established biological risk factors to AIS are growth velocity and potential residual spinal growth assessed by maturity indicators. Spine slenderness and ectomorphy in girls are thought to be risk factors for AIS. Claimed biomechanical susceptibilities are (1) a fixed lordotic area and hypokyphosis and (2) concave periapical rib overgrowth. MRI has revealed neuroanatomical abnormalities in approximately 20% of younger children with IS. A neuromuscular cause for AIS is probable but not established. Possible susceptibilities to AIS in tissues relate to muscles, ligaments, discs, skeletal proportions and asymmetries, the latter also affecting soft tissues (e.g. dermatoglyphics). AIS is generally considered to be multi-factorial in origin. The many anomalies detected, particularly left-right asymmetries, have led to spatiotemporal aetiologic concepts involving chronomics and the genome altered by nurture without the necessity for a disease process. Genetic susceptibilities defined in twins are being evaluated in family studies; polymorphisms in the oestrogen receptor gene are associated with curve severity. A neurodevelopmental concept is outlined for the aetiology of progressive AIS. This concept involves lipid peroxidation and, if substantiated, has initial therapeutic potential by dietary anti-oxidants. Growth saltations have not been evaluated in IS.

Free moment contribution to quiet standing in able-bodied and scoliotic girls

Adolescent idiopathic scoliosis girls are known to display standing imbalance. In addition to a motor deficit problem, the axial torsion of the spine and trunk torsion could reflect an imbalance around the vertical axis. Unlike the excursion of the center of pressure (COP), the forces and moments were rarely addressed to characterize the quiet standing balance. Nonetheless, one dynamical parameter, called free moment (T(V)), representing the vertical torque on the feet can reflect the oscillation around the vertical axis associated to the standing imbalance. The objectives of this study were to test if the free moment variability can be utilized to characterize standing balance in a group of able-bodied and non-treated scoliotic girls and to determine if it was associated with that of the COP among each group of subjects tested. Forty-six adolescent girls with half of them presenting an adolescent idiopathic scoliosis were tested during quiet standing balance. Standing balance was assessed with the subjects standing upright and bare feet on a force plate. RMS and range of COP excursions and free moment were calculated. The scoliotic group displayed higher variability in COP excursion by about 24% than the able-bodied girls. Similarly, the T(V) RMS (P = 0.00136) and range (P = 0.00197) were statistically higher by about 42% in the scoliotic group. The variability of T(V) was associated with that of the COP in both groups. In the medio-lateral direction, the significant correlations between the RMS and range of the free moment and those of the COP were about 0.7 for the able-bodied group and 0.5 for the medio-lateral COP range for the scoliotic group girls. Along the antero-posterior axis, the only statistically significant correlations were observed for the scoliotic group. The free moment variability about the COP measured during quiet standing can be suggestive of an asymmetry control of the trunk around the vertical axis during standing balance. Its variability was more pronounced in scoliotic girls and was associated with the antero-posterior COP variability reflecting both biomechanical and motor control deficits. Free moment calculation could be a supplement insight into the standing balance of scoliotic subjects.

Effect of Body Morphology on Standing Balance in Adolescent Idiopathic Scoliosis

OBJECTIVES

The objective of this study was to determine the effect of body somatotype on standing balance in girls with adolescent idiopathic scoliosis (AIS) who are under observation but not wearing a body brace.

DESIGN

In all, 74 girls participated in this study to form the able-bodied (n = 36) and the AIS (n = 38) groups, having an average age of 13 yrs. Quiet standing balance was tested using a force platform. Afterward, subjects in each group were divided according to their dominant body somatotype, namely endomorphs (fatness), mesomorphs (muscular), or endomorphic ectomorphs (lean).

RESULTS

The center of pressure measured in the anteroposterior position was closer to the heels for the AIS ectomorphic group by approximately 14 mm (P = 0.00497). Only the AIS mesomorphic group displayed a statistically significant 12-mm shift to the right in their center of pressure (P = 0.01211) compared with the able-bodied girls of the same morphotype. In the endomorphic group, the sway area was statistically higher for the scoliotic subjects (P = 0.00839). The distances traveled by the AIS subjects were all statistically longer for all three body morphologic somatotypes.

CONCLUSION

Different postural responses seem to be dependent on body somatotypes. The endomorphic AIS girls had a larger sway area than their able-bodied counterparts while maintaining a similar center of pressure position. The AIS ectomorphic girls had a tendency to lean further back than a comparable able-bodied group. This could be emphasizing a hypokyphotic trunk attitude and increasing the risk of spinal deformity progression. The AIS mesomorphic subjects characterized by a large muscular and bony structure had a tendency to position their center of mass more to their right, indicating less postural adaptability and a stiffer trunk.

Functional classification of patients with idiopathic scoliosis assessed by the Quantec system: a discriminant functional analysis to determine patient curve magnitude

STUDY DESIGN

A stepwise discriminant analysis was used to define a spinal deformity score based on three-dimensional measurements by the Quantec spinal image system (raster stereophotograph).

OBJECTIVE

To provide functional classification of spinal deformity in patients with mild idiopathic scoliosis without using radiographs.

SUMMARY OF BACKGROUND DATA

Most studies classify the degree of spinal deformity in terms of coronal plane radiograph without analyzing transverse rotation. To the authors' knowledge, no studies investigating classification of spinal deformity in idiopathic scoliosis using Quantec system measurements have been documented.

METHODS

In this study, 129 patients with a single curve and 119 patients with a double curve were divided into three groups according to Cobb angle: Group 1 (less than 10 degrees ), Group 2 (10-20 degrees ), and Group 3 (greater than 20 degrees ).

RESULTS

The patients were assigned to the group with the highest scores after application of a stepwise discriminant analysis. The accuracy of the classification system by functional scores for the patients with a single curve was 85% for Group 1, 63.5% for Group 2, and 71.7% for Group 3. The accuracy of classification by functional scores for the patients with a double curve was 87.1% for Group 2 and 76.1% for Group 3.

CONCLUSION

The back surface image study is a method for providing a quantitative assessment of mild spinal deformity, allowing evaluation of patients by integrated three-dimensional parameters with no reference to radiographs.