Measurement error in assessment of vertebral rotation using the Perdriolle torsionmeter.

The Perdriolle torsionmeter assesses vertebral rotation on a spinal radiograph. It is frequently used to measure improvement in spinal derotation following Cotrel-Dubousset instrumentation for scoliosis. In this study, intraobserver and interobserver measurement error was examined during use of the torsionmeter. Intraobserver error was as follows: 53% of the measurements were accurate to within 5 degrees, and 21% erred greater than 10 degrees. Error from the actual value averaged 6 degrees. Interobserver error was as follows: Among six observers, only one third of the radiographs had measurements within 5 degrees of each other. Another one third erred by more than 10 degrees. Because of this significant intraobserver and interobserver error, precise measurements of rotation using the torsionmeter cannot be expected. Efforts to quantify spinal derotation with the torsionmeter after Cotrel-Dubousset instrumentation may not be valid.     

Measurement of vertebral rotation: Perdriolle versus Raimondi

Summary The measurement of vertebral rotation according to Perdriolle is widely used in the French-speaking and Anglo-American countries. Even in this measurement technique there may be a relatively high estimation error because of the not very accurate grading in steps of 5°. The measurement according to Raimondi seems to be easier to use and is more accurate, with 2° steps. The purpose of our study was to determine the technical error of both measuring methods. The apex vertebra of 40 curves on 20 anteroposterior (AP) radiographs were measured by using the Perdriolle torsion meter and the Regolo Raimondi. Interrater and intrarater reliability were computed. The thoracic Cobb angle was 43°, the lumbar Cobb angle 36°. The average rotation according to Perdriolle was 19.1° thoracic (SD 11.14), 12.7° lumbar (11.21). Measurement of vertebral rotation according to Raimondi showed an average rotation of 20.25° in the thoracic region (11.40) and 13.4° lumbar (10.92). The intrarater reliability was r=0.991 (Perdriolle) and r=0.997 (Raimondi). The average intrarater error was 1.025° in the Perdriolle measurement and 0.4° in the Raimondi measurement. Interrater error was on average 3.112° for the Perdriolle measurement and 3.630° for the Raimondi measurement. This shows that both methods are useful tools for the follow-up of vertebral rotation as projected on standard X-rays for the experienced clinicial. The Raimondi ruler is easier to use and is slightly more reliable.     

Segmental vertebral rotation in early scoliosis

Summary In order to investigate the development of the vertebral axial rotation in patients with early scoliosis, the vertebral rotation angle (VRA) was quantified on the basis of 132 anteroposterior radiographs obtained from patients with diagnosed or suspected scoliosis. The rotation was measured in the apical vertebra and in the two suprajacent and two subjacent vertebrae. The radiographic material was divided into a control reference group and three scoliotic groups with varying Cobb angle from 4° up to 30°. In the reference group a slight vertebral rotation was significantly more often seen to the right. In the scoliotic groups, the rotation was most pronounced in the apical segments. The mean VRA toward the convex side was significantly increased in the vertebrae just suprajacent to the apex in curves with a Cobb angle of 8°–15° and in the cranial four vetebrae in curves with a Cobb angle of 16°–30°. Atypical vertebral rotation to the opposite side of the major curve was observed in 12.8% of the cases. There was a significant positive correlation between the VRA and the Cobb angle. These results show that a slight VRA to the right is a common feature in the normal spine, and that the VRA increases with progressive lateral deviation of the spine. It is concluded that the coronal plane deformity in early idiopathic scoliosis is accompanied and probably coupled to vertebral rotation in the horizontal plane.     

Interobserver and intraobserver reliability of the measurement of shoulder internal rotation by vertebral level

Internal rotation is commonly measured as the vertebral level reached by the fully extended thumb. The purpose of this study was to evaluate interobserver and intraobserver reliability with the use of this method. Three male subjects were used for internal rotation measurement. Eleven orthopaedic surgeons and 2 physical therapists served as examiners. Each subject had a radiographic marker placed at a random vertebral level, and the subject's extended thumb was placed at this marker. All examiners then independently measured internal rotation based on vertebral level. To assess intraobserver reliability, this process was repeated twice. After all measurements were completed, an anterior-posterior radiograph of each subject was obtained to define the vertebral level of the marker. This process was repeated 2 additional times with the marker and subject's thumb positioned at different levels than in the previous examination. Intraclass correlation coefficients were calculated to determine reliability. Results demonstrated poor interobserver reliability and reasonable intraobserver reliability. The mean clinical measurement deviated from the mean actual measurement by 1 vertebral level. Despite being the standard method in which shoulder internal rotation is measured, measurement of internal rotation by vertebral level is not readily reproducible between observers.     

Reliability of motion measurements after total disc replacement: the spike and the fin method

As motion preservation is one of the main postulated advantages after total disc replacement (TDR) of the lumbar spine, the quantification of the mobility after TDR seems of special clinical interest. Yet, the best method to assess range of motion (ROM) after TDR remains unclear. The aim of the study was the calculation of 95%-confidence intervals (95%-C.I.) for the measurement error accompanying: (1) different methods (2) different observers and (3) different levels of training for radiographic motion analysis after TDR. In 12 patients the level L4–L5 and in another 12 patients level L5–S1 were measured with the Cobb and the superimposition method on flexion–extension X-rays after monosegmental TDR. Both methods were adopted as the landmarks used the spikes of the prosthesis instead the endplates (spike method) and the fin of the prosthesis instead the whole vertebral body (fin method). Measurements were performed by two experienced (O-I and O-III) and one inexperienced observer (O-II). The adopted spike and fin method showed a better reliability compared to the reported results of the original Cobb and superimposition method. The method used was not clinically relevant for the intraobserver reliability in the experienced observer (95%-C.I.: ±2.0° for the fin and ±2.1 for the spike method) and for the interobserver reliability for two experienced observers (95%-C.I.: –2.8°/+2.8° for the fin and –2.9°/+3.1° for the spike method). The intraobserver reliability for the inexperienced observer was inferior for both methods compared to the experienced observer but no clinically relevant differences could be observed in interobserver reliability measures. The spike and fin method are reliable methods for study protocols dealing with angular motion after TDR as clinically valid conclusions can be drawn with an accuracy of about ±2° for the same observer and with an accuracy of about ±3° for a different observer.     

Combined anterior and posterior instrumentation in severe and rigid idiopathic scoliosis

A prospective clinical and radiographic evaluation of 33 consecutive patients with severe and rigid idiopathic scoliosis (average Cobb angle 93°, flexibility on bending films 23%) were treated with combined anterior and posterior instrumentation with a minimum follow-up of 2 years. All patients underwent anterior release and VDS-Zielke Instrumentation of the primary curve. In highly rigid scoliosis, this was preceded by a posterior release. Finally, posterior correction and fusion with a multiple hook and pedicle screw construct was performed. Thirty patients were operated in one stage, three patients in two stages. Preoperative curves ranged from 80 to 122° Cobb angle. Frontal plane correction of the primary curve averaged 67% with an average loss of correction of 2°. The apical vertebral rotation of the primary curve was corrected by 49%. In all but three patients, sagittal alignment was restored. There were no neurological complications, deep wound infections or pseudarthrosis. Combined anterior and posterior instrumentation is safe and enables an effective three-dimensional curve correction in severe and rigid idiopathic scoliosis.     

Vertebral rotation and thoracic torsion in adolescent idiopathic scoliosis: what is the best radiographic correlate?

BACKGROUND: As a result of the increased appreciation of the three-dimensional nature of scoliosis and modern spinal instrumentation's improved corrective capabilities, there has been renewed interest in the correction and measurement of vertebral rotation. Computed tomography (CT), the gold standard for accuracy, is limited in its clinical utility owing to cost, radiation exposure, and the effects of postural changes on scoliosis curves and vertebral rotation. Consequently, the Perdriolle and Nash-Moe techniques remain the standard measurements for providing a reasonable estimate of pre- and postoperative vertebral rotation because of their simplicity. However, these techniques have considerable interobserver variability, and pedicle screw instrumentation obscures the landmarks necessary for utilizing these techniques for postoperative vertebral rotation assessment. The purpose of the present study was to assess the utility of alternate radiographic measures to assess vertebral rotation and thoracic torsion when compared with conventional measures on pre- and postoperative radiographs and CT evaluation. METHODS: We reviewed the preoperative, immediate postoperative, and final follow-up radiographs, as well as the pre- and postoperative CT scans, of 19 patients (average age 15 years, 6 months) with Lenke 1 curves (average 55 degrees , range 47-66 degrees ), all treated with anterior spinal fusion. Coronal and sagittal Cobb angles as well as vertebral rotation (Perdriolle and Nash-Moe) at the superior uninstrumented, superior instrumented, apical, inferior instrumented, and inferior uninstrumented vertebrae were measured on all films, and vertebral rotation was assessed on the CT scans by a previously described method. Additionally, several measures of thoracic torsion (as a proxy for vertebral rotation and overall deformity improvement) were assessed. These included the rib-vertebral angle difference (RVAD), apical rib hump prominence (RH), apical vertebral body-rib ratio (AVB-R), and apical rib spread difference (ARSD). RESULTS: The postoperative main thoracic curve averaged 26 degrees (range 16-39 degrees , 52% correction) and 29 degrees (range 22-40 degrees , 47% correction) at final follow-up. For apical derotation, the postoperative CT improved from -11.5 degrees to -6.6 degrees and correlated significantly with the Cobb main thoracic curves (42% correction, r = 0.48, P = 0.003). There was weakly positive, but statistically significant, correlation between the pre- and postoperative CT scans and the corresponding Perdriolle and Nash-Moe measures of segmental rotation (r = 0.32-0.40, all P < 0.0001). The RVAD demonstrated poor correlation with the main thoracic curve values and correction, Perdriolle rotation and correction, and CT rotation and correction (r = -0.22-0.37, all P > 0.20). The apical RH demonstrated good correlation with the main thoracic curve (r = 0.65, P < 0.0001), apical Perdriolle rotation (r = 0.57, P < 0.0001), and CT apical rotation (r = 0.53, P = 0.002). We also found moderate correlation between the AVB-R and the main thoracic Cobb, apical Perdriolle, and CT (r = 0.57, 0.59, and 0.49, respectively; all P < 0.005). Similar relationships were found with the ARSD (r = 0.51, 0.47, and 0.43, respectively; all P < 0.02). CONCLUSIONS: The RH, AVB-R, and the ARSD-measures of thoracic torsion-demonstrated moderate to good overall correlation with the main thoracic curve Cobb angles, apical Perdriolle rotation, and apical CT rotation. These should be useful as clinical measures for assessing three-dimensional deformity correction on plane radiographs, especially for the intraoperative evaluation of vertebral derotation and thoracic symmetry restoration.     

Accuracy and applicability of measurement of the scoliotic angle at the frontal plane by Cobb's method,by Ferguson's method and by a new method

Summary A new method for the measurement of scoliotic curves in antero-posterior (AP) radiographs is presented, in which the centre of the surface image of the vertebral bodies of the apical and two end vertebrae of the curvature are defined on the basis of geometric principles. Measurements using the Cobb, the Ferguson, and the new method were performed on ten AP radiographs from each of three groups of young patients with right convex thoracic idiopathic scoliosis with Cobb angles of between 7 and 15°, 16 and 45° and 46 and 80°, respectively. Measurements using the Cobb method yielded significantly higher values than measurements using either the Ferguson method or the new method. In curves with Cobb angles of between 7 and 15°, the values using Ferguson's method were significantly lower than those using the new method; the difference increased significantly in curves with a Cobb angle of 16° or more. The level of significance of the intra- and interobserver differences between the new, the Cobb and the Ferguson methods was significantly higher in curves with a Cobb angle of 16° or more. It is argued that measures of the scoliotic angle obtained by the new method are of greater clinical relevance than those obtained by the two other methods. Unlike the Cobb method, the new method takes into consideration the translation of the apical vertebra in relation to the end vertebrae and not only the tilt of the end vertebrae of the curve. As compared to the Ferguson method, the new method is based on standardised geometric principles, and is not influenced by changes in the shape of the vertebral body. Moreover, the repeatability of the new method is greater than that of both the Cobb method and the Ferguson method. Therefore, it is believed that the new method provides a more accurate measure of the scoliotic curve than do the two other methods, and it is to be preferred over the other two methods in longitudinal evaluation of the development of the curve.     

Dynamic magnetic resonance imaging: reliability of anatomical landmarks and reference lines used to assess pelvic organ prolapse

The aim of this study was to determine the intra- and interobserver reliability of dynamic magnetic resonance (MR) staging in pelvic organ prolapse patients. In 30 patients with pelvic organ prolapse, dynamic MR images were assessed independently by two observers. Various anatomical landmarks to asses pelvic organ prolapse were used in relation to the pubococcygeal line, H-line, and mid-pubic line. Clinical measurement points were assessed in relation to the mid-pubic line. The intraclass correlation coefficients (ICC) were calculated to describe the intra- and interobserver reliability. Overall, the intra- and interobserver reliability of MR imaging measurements was excellent to good. The pubococcygeal line showed superior reliability (ICC range 0.70–0.99). The reliability of clinical measurement points, however, were only moderate (ICC range 0.20–0.96). The intra- and interobserver reliability of quantitative prolapse staging on dynamic MR imaging were good to excellent. The pubococcygeal line appears the most reliable to use.     

Correction of flexible thoracic scoliosis below 65 degrees—A radiological comparison of anterior versus posterior segmental instrumentation applied to similar curves

Direct comparison of the correction of scoliosis achieved by different surgical methods is usually limited by the heterogeneity of the patients analyzed (their age, curve pattern, curve magnitude, etc.). The hypothesis is that an analysis of comparable scoliotic curves treated by different implant systems could detect subtle differences in outcome. The objective of this study was therefore: (1) to measure the 3D radiological parameters of scoliotic deformity and to quantify their postoperative changes, and (2) to compare the radiographic results achieved with one anterior and one posterior instrumentation methods applied to similar curves but representing different mechanisms of correction. Material and methods: The clinical notes and radiographs of 46 patients operated on for adolescent idiopathic scoliosis were reviewed. The inclusion criteria consisted of: a single thoracic curve, right convex, a frontal Cobb angle minimum of 45° and a maximum of 65°, flexibility on a lateral bending test of more than 30%, and a Risser test value of between 1 and 4. The operative procedures were: Cotrel-Dubousset instrumentation (CDI) for 25 patients (the CD group) and correction by anterior instrumentation (Pouliquen plate) for 21 patients (the ANT group). Preoperative and postoperative long cassette standing antero-posterior and lateral radiographs were examined. The frontal and sagittal thoracic Cobb angle, apical vertebra transposition (AVT), apical vertebra rotation (AVR), lowest instrumented vertebra (LIV) tilt, C7 vertebra shift and rib cage shift (RCS) were all compared. A computed reconstruction was produced with Rachis-91 software. Vertebral axial rotation angle was evaluated throughout the spine. Results: Postoperative assessment revealed a mean correction of the frontal Cobb angle of 37.0° for the CD group and 41.0° for the ANT group. The AVT operative correction was 45.8 and 42.7 mm, respectively, and AVR correction was 1.8 and 12.6°, respectively. The postoperative change of the sagittal Th4–Th12 Cobb angle was not significant for any method but it was significant (P=0.05) for the CD group if the curves were divided preoperatively into hypokyphotic and normokyphotic subgroups and then analyzed separately. Computed assessment demonstrated a correction of segmental axial rotation of more than 50% in the main thoracic curve in the ANT group, significantly more than that in the CD group (P<0.001). Conclusions: Anterior instrumentation provided better correction of the vertebral axial rotation and of the rib hump. CD instrumentation was more powerful in translation and more specifically addressed the sagittal plane: the postoperative thoracic kyphosis angle increased in the hypokyphotic curves and slightly decreased in the normokyphotic curves.     

Interobserver reliability of the Mallet score

The interobserver reliability of the Mallet score for active shoulder function was assessed by three experienced observers in a group of 30 children with an obstetric brachial plexus lesion (mean age 7.1 years, range 4.5-10 years). Interobserver reliability, measured using weighted kappa, was good. Kappa varied between 0.37 and 0.84 and differed between the different aspects of the Mallet score and different pairs of observers. In decreasing order, mean weighted kappa was 0.75 for abduction, 0.73 for hand to neck, 0.67 for hand to spine, 0.6 for external rotation and 0.53 for hand to mouth.     

Endoscopic surgery on the thoracolumbar junction of the spine

It is a measurement of Cobb’s angles between adolescent (AIS) and juvenile (JIS) idiopathic scoliosis who had stable curves (variation <5 degrees) in more than three visits. Main objective of this paper is to measure inter- and intra-observer reliability of measurements between AIS and JIS who had stable curves in regular follow-up. Twenty-nine JIS and 44 AIS patients who had stable curves without bracing were identified using PACS system. Two observers independently measured Cobb’s angle twice on first, during follow-up and final radiogram using computer-based digital radiogram. Both observers were given pre-decided level of upper and lower end plates. Inter- and intra-observer reliability of the measurement was calculated using Pearson correlation-coefficient test between JIS and AIS group. There was no significant difference in Cobb’s angle in all measurements by both observers either in JIS (p = 0.756, range 0.706–0.815; ANOVA) or AIS (p = 0.871, range 0.795–0.929; ANOVA) group which suggested that there is no significant difference in Cobb’s angle in repeated measurements. Intra-observer reliability for JIS (r = 0.600, range 0.521–0.751; Pearson test) was less than AIS (r = 0.969, range 0.943–0.984; Pearson test); and similarly, inter-observer reliability for JIS (r = 0.547, Pearson test) was also less than AIS (r = 0.961, Pearson test) which indicates that Cobb’s angle measurement is less reliable in patients who have juvenile idiopathic scoliosis. Using the identical condition for measurements in both the groups, we could find only one reason for less reliability in JIS group and that is poor demarcation of the vertebral end-plates in this group. This poor inter- and intra-observer reliability in JIS due to ill-defined endplates can be reduced by measuring all previous curves along with latest curves at the same time during the follow-up of patients with JIS to decide about the progression of curves and treatment options.     

MRI evaluation of rotational alignment and synovitis in patients with pain after total knee replacement

Component malalignment can be associated with pain following total knee replacement (TKR). Using MRI, we reviewed 50 patients with painful TKRs and compared them with a group of 16 asymptomatic controls to determine the feasibility of using MRI in evaluating the rotational alignment of the components. Using the additional soft-tissue detail provided by this modality, we also evaluated the extent of synovitis within these two groups. Angular measurements were based on the femoral transepicondylar axis and tibial tubercle. Between two observers, there was very high interobserver agreement in the measurements of all values. Patients with painful TKRs demonstrated statistically significant relative internal rotation of the femoral component (p = 0.030). There was relative internal rotation of the tibial to femoral component and combined excessive internal rotation of the components in symptomatic knees, although these results were significant only with one of the observers (p = 0.031). There was a statistically significant association between the presence and severity of synovitis and painful TKR (p < 0.001). MRI is an effective modality in evaluating component rotational alignment.     

Vertebral centroid measurement of lumbar lordosis compared with the Cobb technique.

STUDY DESIGN: An observational study in which vertebral centroid measurement of lumbar lordosis, developed in this study, was used to examine lumbar curvature. The intra- and interobserver reliability of the vertebral centroid measurement of lumbar lordosis and the Cobb technique were compared. OBJECTIVES: To evaluate the reliability of a new method of measuring lumbar lordosis and to examine the changes in the lordotic curve from 0 degree to 90 degrees flexion of the trunk. SUMMARY OF BACKGROUND DATA: Several different methods are used to measure lumbar lordosis. The Cobb technique, based on measurement of vertebral endplates, is the method most frequently adopted for clinical diagnosis. However, because of the variations in the vertebral endplate architecture, the vertebral surface angle is difficult to identify. This reduces the reliability of the Cobb technique. METHODS: Lateral radiographs of 16 study participants were taken from the upright position to a trunk flexion of 90 degrees in 30 degrees increments. The lumbar lordotic curve was measured by three observers individually using two applications of the traditional Cobb technique and the vertebral centroid measurement of lumbar lordosis. RESULTS: Correlation coefficients of lumbar lordosis between the two methods ranged from 0.589 to 0.772 with participants standing upright (all P < 0.05). Interobserver reliability coefficients were 0.903 for vertebral centroid measurement of lumbar lordosis, 0.826 for Cobb (L1-L5), and 0.784 for Cobb (L1-S1), although the three measurements all revealed an excellent intraobserver reproducibility (r greater than 0.9). The vertebral centroid measurement of lumbar lordosis showed the smallest mean absolute differences between any two observers' measurements (< 1.7 degrees). CONCLUSIONS: The findings from this study indicate that the vertebral centroid measurement of lumbar lordosis is more reliable than the Cobb method for assessing lumbar lordosis. The vertebral centroid measurement of lumbar lordosis also can be used to evaluate the actual lumbar curvature in outline at various angles of trunk flexion.     

Evaluation of deformities and pulmonary function in adolescent idiopathic right thoracic scoliosis

Summary Seventy patients with adolescent idiopathic right thoracic scoliosis had full assessment of their pulmonary function using a computerised pulmonary function system. Their mean age at evaluation was 13.8 years. The following measurements were obtained from anteroposterior and lateral standing and antero-posterior supine bending radiographs: lateral curvature, vertebral rotation, kyphosis, maximum sterno-vertebral distance and apical rib-vertebral angles. Using the above measurements, the flexibility of curve, vertebral rotation and rib-vertebral angle asymmetry were calculated. Patients were classified into three groups on the basis of their predicted vital capacity, to determine whether radiological features of deformity can help identify patients with compromised pulmonary function. The mean Cobb angle and vertebral rotation for the 70 patients were 50° (range 35–100°) and 22° (range 1–44°) respectively. The mean flexibility of curve and vertebral rotation were 52% and 49% respectively. Mean thoracic kyphosis was 25%, ranging from -7 to 55%. Of the patients with Cobb angle less than 90%, 71% had vital capacity less than 80% of predicted values, and of these, 18% had marked compromise of vital capacity (less than 60% of predicted values). Mean values of Cobb angle, vertebral rotational flexibility, kyphosis, rib-vertebral angle asymmetry (in standing as well as supine bending radiographs) differed significantly between patients with more than 80% of predicted vital capacity and those with 60% or less of predicted values. Radiological features indicative of better pulmonary function were: rotational flexibility exceeding 55%, rib-vertebral angle asymmetry (standing) less than 25% and kyphosis greater than 15%. Two deformity parameters—that give a better prediction of pulmonary function than the widely used Cobb angle, vertebral rotational flexibility and rib-vertebral angle asymmetry—were identified in this study.     

Assessment of relative rotational alignment in total knee arthroplasty: usefulness of the modified Eckhoff method

In 1995, Eckhoff and colleagues demonstrated a new method for assessing relative rotational alignment of the femoral and tibial components in total knee arthroplasty (TKA). We studied the usefulness of a modified Eckhoff method. Five knee prostheses (Natural Knee, Deltafit, and three different sizes of Press-Fit Condylar) were used in an in-vitro study. A series of lateral radiographs were taken with the femoral component rotated in 1° increments from 15° internal rotation to 15° external rotation. The rotation of the implant was calculated based on the geometric relationship of pegs that were present symmetrically on the medial and lateral sides of the femoral components in all prostheses. In a study of the clinical applications, two independent observers measured the relative rotation of 18 knees in 16 patients after TKA, using this method. In the in-vitro study, the measurement error of rotation averaged 0.27°, and the maximum error was 0.96°. Clinically, the mean difference between the measurements of the two observers in each knee was 0.64°; there was a high correlation between the values measured by the two observers (r = 0.89; P < 0.0001). This is a useful method for determining the relative rotation in TKA accurately and reproducibly. Received for publication on June 30, 1999; accepted on Aug. 24, 1999     

Intraobserver reproducibility and interobserver reliability of cervical spine measurements

Lateral flexion-extension radiographs of 72 patients with Down syndrome were used to assess the interobserver reliability and intraobserver reproducibility of the atlanto-dens interval, Wiesel-Rothman measurement, occiput atlas angle, and Power's ratio in flexion and extension. The radiographs were reviewed by three blinded observers on three different occasions with at least a 1-month interval between assessments. The intraclass correlation coefficient was used to measure the reproducibility of the measurements from a given observer and the reliability between different observers. With the exception of observer one, the atlanto-dens interval had a statistically significant intraobserver agreement compared with any of the other measurements (p < 0.05). The atlanto-dens interval and the Wiesel-Rothman measurements tended to have better correlation between observers, although there was only fair agreement. The agreement, however, was statistically significant (p < 0.05) compared with Power's ratio. The degree of intraobserver reproducibility and interobserver reliability may make it difficult to base treatment protocols on these measurements.     

The Reliability and Accuracy of the Medial Malleolar Fracture Classification Based on 3D CT Reconstruction

Objective

There is a new medial malleolar fracture classification based on 3D CT reconstruction. However, there is no study assessing the reliability and accuracy of the new classification system and comparison between the new and the classic classification. This study aimed to compare the reliability and accuracy of the medial malleolar fracture classification based on 3D CT reconstruction and the Herscovici classification system.

Methods

We retrospectively analyzed the consecutive ankle fractures in our hospital from January 2013 to September 2020. Five inexperienced and five experienced orthopedic surgeons were included as observers to assess 68 cases with medial malleolar fractures. Ten evaluators classified the cases according to the two classification systems. The reference results of each case were made by the consensus of three senior trauma surgeons. The interobserver reliability, intraobserver reliability, and accuracy were evaluated at an interval of 6 weeks using Fleiss's kappa (κ) statistics.

Results

We found substantial interobserver and intraobserver reliability and 81.4% accuracy for the new classification, which was statistically superior to the Herscovici classification (P < 0.05). The reliability and accuracy of both classifications were similar in inexperienced and experienced groups, except for type III in the new classification. The interobserver reliability of type II was the best (P < 0.05), and the intraobserver reliability of IVc ranked the worst (P < 0.05) in the new classification.

Conclusion

The reliability and accuracy of the new classification are superior to the Herscovici classification. Clinical experiences will not affect the assessment of both classification systems in most instances.     

Primary thoracoplasty and pedicle screw instrumentation in thoracic idiopathic scoliosis

Thoracoplasty in combination with spine fusion is an established method to address the rib cage deformity in idiopathic scoliosis. Most reports about thoracoplasty and scoliosis correction focused on Harrington or CD instrumentation. We report a retrospective analysis of 21 consecutive patients, who were treated with pedicle screw instrumentation for idiopathic thoracic scoliosis and concomitant thoracoplasty. Minimal follow up was 24 (24–75) months. Indication for thoracoplasty was clinical rib prominence of more than 15°. In average there was a 44% correction of clinical rib hump, from 18 (15–25°) to 10° (0–18°) (p<0.0001) and a 40% correction of radiological rib hump, from 15 (5–20°) to 9°(2–15°) (p<0.0001). The preoperative pulmonary function, accessed by forced vital capacity (FVC) and one-second forced expiratory volume (FEV1), remained unchanged at the last follow up. The distal end of fusion was the end vertebra of the curve in 83.3% and the end vertebra plus one in 16.7% of the patients. There was a 68% correction of instrumented primary thoracic curves, from 60 (45–85°) to 19°(5–36°) (p<0.0001), and a 45% correction of non-instrumented secondary lumbar curves, from 40 (28–60°) to 22°(8–38°) (p<0.0001). Apical vertebral rotation (AVR) of the thoracic curves improved 54%, from 24 (10–35°) to 11° (5–20°) (p<0.0001). The tilt of lowest instrumented vertebra (LIV) improved 68%, from 28 (20–42°) to 9°(3–20°) (p<0.0001). There was no significant change in sagittal profile of the spine. Analysis with SRS-24 questionnaire showed that the majority of the patients were very satisfied with the outcome. A matched control group (n=21) operated by the same surgeon with the same operation technique but without concomitant thoracoplasty was chosen for comparison. The scoliosis correction in the two groups was comparable. The patients without thoracoplasty had 37% spontaneous improvement of the clinical rib hump.     

Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages

Summary Three-dimensional (3-D) reconstructions of the spine are being used with increasing frequency to describe scoliotic deformities, but the reproducibility of most of these techniques and the implication for the reliability of measurements made on the reconstructions has not been reported. How reliable are these reconstructions, and can a clinician interpret with confidence the results of studies based on such mathematical models? A reproducibility study of various computerised measurements obtained from 3-D reconstructions of the spine and rib cage for five subjects with adolescent idiopathic scoliosis was done to evaluate the errors associated with repeated measurements and compare them with inter-and intraobserver errors reported for similar commonly used clinical measurements. The mean variation for the Cobb angle differed according to the plane of computation from 0.6° in the frontal plane to 6.7° in the sagittal plane; vertebral axial rotation varied from 2.3° to 5.9° according to the vertebral level, and rib hump measurements displayed an average variation of 1.4°. All these variations are below or within the error levels reported for equivalent 2-D measurements used by clinicians, which suggests that this 3-D model of idiopathic scoliosis may be used with confidence for clinical evaluations.