Standing Anteroposterior Radiographs Research Articles

New evaluation indices for rotational knee angles in standing anteroposterior knee radiographs.

Identifying the time course of rotational knee alignment is crucial for elucidating the etiology in knee osteoarthritis. The aim of this study was to propose new rotational indices for calculating the change in relative rotational angles between the femur and tibia in standing anteroposterior (AP) radiographs. Forty healthy elderly volunteers (20 women and 20 men; mean age, 70 ± 6 years) were assessed. The evaluation parameters were as follows: (1) femoral rotational index: the distance between the sphere center of the medial posterior femoral condyle and the lateral edge of the patella, and (2) tibial rotational index: the distance between the medial eminence of the tibia and the lateral edge of the fibula head. The indices were standardized by the diameter of the sphere of the medial posterior femoral condyle. This study (1) identified the relationship between changes in rotational indices and the simulated rotational knee angles in the standing position, (2) proposed a regression equation for the change in relative rotational angles between the femur and tibia in standing AP radiographs, and (3) verified the accuracy of the regression equation. The rotational indices increased in direct proportion to simulated rotational knee angles (femoral index: r > 0.9,p <0.0001; tibial index: r >0.9, p <0.0001). Based on the results, the regression equation with the accuracy of 0.45 ± 0.26° was determined. The proposed regression equations can potentially predict the change in relative rotational angles between the femur and tibia in a pair of standing AP radiographs taken at different dates in longitudinal studies.

Effect of pelvic tilt and rotation on cup orientation in standing anteroposterior radiographs.

Individual pelvic tilt and rotation have wide variability that can affect the measurement of cup orientation in anteroposterior (AP) radiographs. The purpose of this study was to analyse the effect of pelvic tilt and rotation on radiographic measurements of cup orientation. A total of 53 patients (63 hips) were included in this study. The patients underwent a computed tomography study with standing AP pelvis radiographs taken both preoperatively and approximately 3 months postoperatively. We used 2-dimensional/3-dimensional matching to measure the pelvic tilt and rotation, and the non-standardised and standardised cup orientation. There was no difference in the pelvic tilt and rotation between the preoperative and postoperative radiographs. The distribution of the differences between the non-standardised and standardised cup anteversion exhibited a change within 5° in only 34/63 (54%) hips. The pelvic tilt correlated with the difference between the non-standardised and standardised cup anteversion, but the pelvic rotation did not. When all 63 hips were separated into the right and left sides, the pelvic rotation inversely correlated with the pelvic tilt-adjusted difference between the non-standardised and standardised cup anteversion of the right side but directly correlated with that of the left side. The current study demonstrated that the measurement of cup anteversion in standing AP radiographs is significantly affected by both the pelvic tilt and pelvic rotation. An improved understanding of the pelvic orientation may eventually allow for desired cup positioning on a patient-specific basis to potentially reduce complications associated with the malposition of the cup.

Does Tibial Slope Affect Perception of Coronal Alignment on a Standing Anteroposterior Radiograph?

BackgroundA standing anteroposterior (AP) radiograph is commonly used to evaluate coronal alignment following total knee arthroplasty (TKA). The impact of coronal alignment on TKA outcomes is controversial, perhaps due to variability in imaging and/or measurement technique. We sought to quantify the effect of image rotation and tibial slope on coronal alignment. MethodsUsing a standard extramedullary tibial alignment guide, 3 cadaver legs were cut to accept a tibial tray at 0°, 3°, and 7° of slope. A computed tomography scan of the entire tibia was obtained for each specimen to confirm neutral coronal alignment. Images were then obtained at progressive 10° intervals of internal and external rotation up to 40° maximum in each direction. Images were then randomized and 5 blinded TKA surgeons were asked to determine coronal alignment. Continuous data values were transformed to categorical data (neutral [0], valgus [L], and varus [R]). ResultsEach 10° interval of external rotation of a 7° sloped tibial cut (or relative internal rotation of a tibial component viewed in the AP plane) resulted in perception of an additional 0.75° of varus. ConclusionThe slope of the proximal tibia bone cut should be taken into account when measuring coronal alignment on a standing AP radiograph.

Association between Sacral Slanting and Adjacent Structures in Patients with Adolescent Idiopathic Scoliosis.

BackgroundSacral slanting is a frequent unique phenomenon in patients with adolescent idiopathic scoliosis (AIS) and may be important for selecting the distal fusion level. However, the reason of the phenomenon remains unknown. The purpose of this study was to determine the association between sacral slanting and adjacent structures in patients with AIS.MethodsA total of 303 AIS patients who underwent both whole spine standing anteroposterior (AP) and whole leg standing AP radiography were included. The degree of sacral slanting, pelvic obliquity, lumbar curve angles (L1-L4), and L4 tilt were assessed on whole spine standing AP radiographs. Whole leg standing AP radiographs were used to assess the degree of leg length discrepancy (LLD). Demographic data and radiological parameters were analyzed descriptively. Pearson correlation analysis and partial correlation analysis of the parameters were performed. A p-value of less than 0.05 was considered statistically significant.ResultsThe proportion of patients with ≥ 5° of sacral slanting among those with < 3° of pelvic obliquity was 8.9% (27/303). Thirty-two patients (10.6%, 32/303) showed more than 10 mm of LLD. Sacral slanting was positively correlated with pelvic obliquity and lumbar curve (r = 0.445 and r = 0.325, respectively). Pelvic obliquity was also correlated with LLD and L4 tilt (r = 0.123 and r = 0.311, respectively). However, partial correlation analysis showed that LLD was not directly correlated with sacral slanting (r = −0.034). ConclusionsSacral slanting can be thought to be a compensatory mechanism for large lumbar curves, which is accompanied by pelvic obliquity. In contrast, a congenitally slanted upper sacrum may contribute to scoliosis in some cases. LLD was not directly correlated with sacral slanting.

Lowest instrumented vertebra selection in Lenke 3C and 6C scoliosis: what if we choose lumbar apical vertebra as distal fusion end?

The aim of this study was to investigate whether or not post-op curve behaviour differs due to different choices of lowest instrumented vertebra (LIV) with reference to lumbar apical vertebra (LAV) in Lenke 3C and 6C scoliosis. We reviewed all the AIS cases surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 3C or 6C scoliosis who were treated with posterior pedicle screw-only constructs; (2) 2-year radiographic follow-up. All the included patients were categorized into three groups based on the relative position of LIV and LAV: Group A-the LIV was above the LAV; Group B-the LIV was at the LAV; Group C-the LIV was below the LAV. All the radiographic parameters were then compared among the groups. All image data were available in our picture archiving and communication systems. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four times (pre-op, post-op, 3-month and 2-year). In each standing AP radiograph, centre sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, followed by measuring T1-CSVL, LIV-CSVL, (LIV+1)-CSVL, LAV-CSVL and thoracic AV-CSVL distance. In addition, the Cobb angles of major thoracic and lumbar curves were measured at the four times and the correction rates were then calculated. Of the 278 patients reviewed, 40 met the inclusion criteria; 11 of these were included in Group A (LIV above LAV), another 11 in Group B (LIV at LAV) and the remaining 18 in Group C (LIV below LAV). At 2-year follow-up, the lumbar vertebrae such as LIV, LIV+1 and LAV were all more deviated than before surgery in Group A (LIV above LAV), whereas in Group B and C (LIV at and below LAV) they were all less deviated than before surgery. No significant differences were found in thoracic or lumbar correction rate, global coronal balance and incidence rate of trunk shift among the three groups. In conclusion, in Lenke 3C and 6C scoliosis, post-op lumbar curve behaviour differs due to different choices of LIV with reference to LAV, that is, the deviation of lumbar curve improves when the LIV is either at or below the LAV but deteriorates when the LIV is above the LAV. Although the greatest correction occurs when the LIV is below the LAV, choosing LAV as LIV can still be the optimal option in certain cases, since it can yield similar correction while preserving more lumbar mobility and growth potential.

Extensive fusion for Lenke 3C and 6C scoliosis: a two year radiographic follow-up

To investigate the correction effectiveness, incidence rate of distal adding on, and post-operative spinal balance in Lenke 3C and 6C AIS treated with extensive fusion using posterior pedicle screw-only constructs. We reviewed all AIS cases surgically treated in our institution between 2002 and 2008. The inclusion criteria were as follows: (1) Lenke 3C or 6C scoliosis patients who were treated with extensive fusion using posterior pedicle screw-only constructs; (2) minimum two year radiographic follow-up; (3) the lowest instrumented vertebra (LIV) ended at L2, L3 or L4 level. All image data were available in our picture archiving and communication systems (PACSs) , and all radiographic measurements were performed. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four different time points (pre-op, post-op, three months, and two years). In each standing AP radiograph, CSVL (center sacral vertical line, the vertical line bisecting the proximal sacrum) was first drawn, followed by measurement of the translation (deviation from the CSVL) of some key vertebrae, such as the lowest instrumented vertebra (LIV), LIV + 1 (the first vertebra below LIV), lumbar apical vertebra, thoracic apical vertebra and T1, enabling depiction of how translation of different parts of the spine changes over time. Additionally, the Cobb angles of major thoracic and lumbar curves were measured at the different time points and the correction rate was calculated. Of the 278 patients reviewed, 25 met the inclusion criteria. Immediately after surgery, satisfactory corrections were achieved from the perspective of not only Cobb angle but also vertebral translation. And the corrections were well retained in the following two years. The incidence rate of distal adding-on was low in this group of patients. In the course of two years following surgery, only six patients had an increase of greater than 5 mm in LIV + 1 translation, and among which only two patients had greater than 10 mm. Regarding global balance, overall, it neither improved nor deteriorated after extensive fusion. Furthermore, trunk shift was found in only three patients at two year follow-up. In Lenke 3C and 6C scoliosis, extensive fusion can produce satisfactory corrections from the perspectives of both Cobb angle and vertebral translation and rarely causes significant distal adding-on, global imbalance or trunk shift.

Development of a Clinical Prediction Rule for Diagnosing Hip Osteoarthritis in Individuals With Unilateral Hip Pain

Prospective cohort/predictive validity study. To determine the diagnostic accuracy of common clinical examination items and to construct a preliminary clinical prediction rule for diagnosing hip osteoarthritis (OA) in individuals with unilateral hip pain. The current gold standard for the diagnosis of hip OA is a standing anteroposterior (AP) radiograph of the pelvis. Other than for Altman's criteria, little research has been done to determine the accuracy of clinical examination findings for diagnosing hip OA. Seventy-two subjects completed the study. Each subject received a standardized history, physical examination, and standing AP radiograph of the pelvis. Subjects with a Kellgren and Lawrence score of 2 or higher based on the radiographs were considered to have definitive hip OA. Likelihood ratios (LRs) were computed to determine which clinical examination findings were most diagnostic of hip OA. Potential predictor variables were entered into a logistic regression model to determine the most accurate set of clinical examination items for diagnosing hip OA. Twenty-one (29%) of the 72 subjects had radiographic evidence of hip OA. A clinical prediction rule consisting of 5 examination variables was identified. If at least 4 of 5 variables were present, the positive LR was equal to 24.3 (95% confidence interval: 4.4-142.1), increasing the probability of hip OA to 91%. The preliminary clinical prediction rule provides the ability to a priori identify patients with hip pain who are likely to have hip OA. A validation study should be done before the rule can be implemented in routine clinical practice.

Fixed lumbar apical vertebral rotation predicts spinal decompensation in lenke type 3c adolescent idiopathic scoliosis after selective posterior thoracic correction and fusion

Retrospective radiographic review of surgically treated double major curves (Lenke type 3C) in adolescent idiopathic scoliosis. To evaluate the role of selective posterior thoracic correction and fusion in double major curves with third generation instrumentation and to identify preoperative radiographic parameters that predict postoperative coronal spinal decompensation. Traditionally the surgical treatment of double major curves consists of fusion of both the thoracic and the lumbar curve. Few attempt to perform selective thoracic fusion in this curve pattern because of the potential to create spinal imbalance. Thirty-six patients with Lenke type 3C curves underwent a selective posterior thoracic correction and fusion with either Cotrel-Dubousset instrumentation or the Universal Spine System. Radiographs were evaluated to assess coronal and sagittal balance, curve flexibility, and curve correction at a minimum follow up of 2 years. Postoperative coronal spinal decompensation was investigated with respect to preoperative radiographic parameters on standing anteroposterior (AP), standing lateral radiographs, thoracic and lumbar supine side-bending radiographs. Coronal spinal decompensation was defined as plumbline deviation of C7 of more than 2 cm with respect to the centre sacral vertical line (CSVL) within 2 years of surgery. Twenty-six patients (72%) showed satisfactory frontal plane alignment patients (28%) showed coronal spinal decompensation. Significant group differences, however, were identified for lumbar apical vertebral rotation, measured according to Perdriolle (La scoliose. Son êtude tridimensionnelle. Maloine, Paris, pp 179, 1979) (A 16 degrees , B 22 degrees , P = 0.02), percentage correction (derotation) of lumbar apical vertebrae in lumbar supine side-bending films in comparison to standing AP radiographs (A 49%, B 27%, P = 0.002) and thoracic curve flexibility (A 43%, B 25%, P = 0.03). High correlation was noted between postoperative decompensation and derotation of lumbar apical vertebrae in pre-operative lumbar supine side-bending films with a critical value of 40% (Pearson correlation coefficient; P = 0.62, P < 0.001). Ten of 36 patients (28%) with Lenke type 3C adolescent idiopathic scoliosis showed coronal spinal decompensation of more than 2 cm after selective posterior thoracic correction and fusion. Lumbar apical vertebral derotation of less than 40% provided the radiographic prediction of postoperative coronal spinal imbalance. We advise close scrutiny of the transverse plane in the lumbar supine bending film when planning surgical strategy.

The accuracy of the Palpation Meter (PALM) for measuring pelvic crest height difference and leg length discrepancy.

Test-retest reliability and validity. To determine the validity and reliability of the Palpation Meter (PALM). Leg length discrepancy (LLD) has been associated with a variety of musculoskeletal disorders. Therefore, the clinical measurement of LLD has become a routine and important part of the physical examination. The PALM is an instrument that was recently developed to indirectly measure LLD, but little is known about its measurement properties. Fifteen healthy and 15 symptomatic subjects with suspected LLD participated in this study. Measurements of pelvic crest height difference (PD) were obtained by 2 examiners using the PALM. A standing antero-posterior (AP) radiograph of each subject's pelvis was taken, and PD and LLD (femoral head height difference) were determined from the radiograph for comparison with the PALM values. Intraclass correlation coefficients (ICCs) were calculated to determine the validity and reliability estimates of the PALM. For all subjects, the validity estimates (ICC2,3) of the PALM for PD were excellent (0.90 for rater 1 and 0.92 for rater 2) when compared with the standing AP radiograph of the pelvis. The PALM was less accurate (ICC2,3 of 0.76 and 0.78 for rater 1 and 2, respectively) as an indirect estimate of LLD. Intrarater reliability for each rater was excellent (ICC3,3 = 0.97 and 0.98) and interrater reliability was very good (ICC2,3 = 0.88). The PALM is a reliable and valid instrument for measuring PD. Clinicians should consider this convenient, cost-effective clinical tool as an alternative to radiographic measurement of pelvic crest height difference.