Inter-observer reliability of radiographic classifications and measurements in the assessment of Perthes' disease

The Ambiguity of Names and Landmarks in Radiographs of the Pediatric Pelvis: Variations and a Historical Perspective

For over a century, the plain radiograph has been used to measure and predict the development of pediatric hip conditions. Classic measurements, such as the acetabular index, the center-edge angle, and the migration percentage, have stood the test of time and remain the default tools for any pediatric orthopaedic surgeons. However, in contemporary research, the terminology regarding these measurements has become markedly inconsistent. A substantial number of synonyms, acronyms, and similar, but not identical, terms are used to label measurements. This is perhaps unsurprising, considering decades of use and numerous suggested modifications. The results of treatment cannot be reliably compared if the measured parameters are not identical, and scientific analysis of disease requires consistent terminology. In this review, we aim both to provide historical definitions and identification of radiographic landmarks commonly used in three parameters of interest on pediatric AP radiographs and to examine the variability of landmarks and definitions in contemporary research.

An AI based classifier model for lateral pillar classification of Legg-Calve-Perthes

We intended to compare the doctors with a convolutional neural network (CNN) that we had trained using our own unique method for the Lateral Pillar Classification (LPC) of Legg-Calve-Perthes Disease (LCPD). Thousands of training data sets are frequently required for artificial intelligence (AI) applications in medicine. Since we did not have enough real patient radiographs to train a CNN, we devised a novel method to obtain them. We trained the CNN model with the data we created by modifying the normal hip radiographs. No real patient radiographs were ever used during the training phase. We tested the CNN model on 81 hips with LCPD. Firstly, we detected the interobserver reliability of the whole system and then the reliability of CNN alone. Second, the consensus list was used to compare the results of 11 doctors and the CNN model. Percentage agreement and interobserver analysis revealed that CNN had good reliability (ICC = 0.868). CNN has achieved a 76.54% classification performance and outperformed 9 out of 11 doctors. The CNN, which we trained with the aforementioned method, can now provide better results than doctors. In the future, as training data evolves and improves, we anticipate that AI will perform significantly better than physicians.

Validation of the height-width measurement in Perthes disease among interpreters of different experience levels

The epiphyseal height and metaphyseal width ratio estimated lateral pillar involvement with limited generalizability among various interpreters. The aim of the study was to evaluate the reliability and the validity of height-width ratio measurement in Perthes disease among interpreters of different experience levels. A cross-sectional study was conducted between 2019 and 2020. We included four groups of interpreters: orthopaedic residents, orthopaedic fellows, radiology residents and radiology fellows who were unaware of radiographic study materials. Each interpreter blindedly evaluated Perthes hip radiographs twice at 1-month intervals using the height-width ratio method. Patients' and interpreters' characteristics, height-width ratio and height-width ratio converted to lateral pillar classification (A, B and C) were collected. Intra- and interobserver reliability validated with the paediatric orthopaedist were estimated. Twenty-four interpreters assessed 18 Perthes radiographs. Intraobserver level of agreement (95% confidence interval) for height-width ratio was 0.022 (-0.017 to 0.062), -0.027 (-0.074 to 0.019), -0.010 (-0.095 to 0.074) and 0.019 (-0.109 to 0.146); and interobserver reliability compared with the paediatric orthopaedist was -0.007 (-0.091 to 0.077), 0.003 (-0.056 to 0.061), -0.021 (-0.077 to 0.035) and -0.002 (-0.090 to 0.086) for orthopaedic residents and fellows, radiology residents and fellows, respectively. Kappa statistics of height-width ratio converting to lateral pillar classification indicated intraobserver agreement of orthopaedic residents and fellows, radiology residents and fellows was 0.83, 0.75, 0.54 and 0.91; and interobserver agreement compared with the paediatric orthopaedist was 0.92, 0.83, 0.42 and 0.83, orderly. Height-width ratio and lateral pillar estimation by orthopaedic and radiology trainees have moderate to excellent reliability. Level of evidence: Level II - diagnostic study.

Stability in Pelvic Triple Osteotomies in Children Using Resorbable PLGA Screws for Fixation

BACKGROUND

The triple pelvic osteotomy (TPO) is a major redirectional osteotomy used to improve the acetabular coverage of the femoral head in selected pediatric patients with hip disorders. Traditionally the iliac osteotomy is stabilized by metal screws that require a second surgery for removal. Despite favorable results for both adults and children in related pelvic osteotomies, resorbable implants have not previously been used for TPOs.This study aims to suggest a novel modified TPO surgical method in children using resorbable poly lactic-co-glycolic acid (PLGA) screws for fixation and to radiographically evaluate the postoperative stability achieved by these implants in a case series.

METHODS

All patients (n=11) with dysplasia of the hip (2), Perthe disease (5), or Down syndrome (4), who underwent primary TPO surgery during 2013 to 2019, using resorbable PLGA screws for fixation were included. The stability of the osteotomy was evaluated in the postoperative radiograph series using the acetabular index, migration percentage, Sharp's angle and the center-edge angle. The osteotomy angle was introduced as a parameter to confirm the postoperative integrity of the achieved correction. All cases were evaluated until radiographic healing of the iliac osteotomy. Hospital notes were analyzed for complications or local reactions in relation to the implants.

RESULTS

In all studied hips, the overall achieved correction was well maintained. The mean (SD) correction achieved, from the preoperative images to the last measurable postoperative image, was a 16.7 degrees decrease for Sharp angle, a 20.9 degrees decrease in acetabular index and a 24.7 degrees increase for the center-edge angle, respectively. There were no complications related to the bioabsorption of the implants.

CONCLUSION

The present findings suggest that the modified TPO method, using resorbable PLGA screws, provides sufficient stability and appears to be a promising alternative to traditional TPO. Avoiding implant removal is a major benefit in a pediatric population. Resorbable screws enable the surgeon to place implants with more degrees of freedom since later implant removal is not a limiting factor.

LEVEL OF EVIDENCE

Level IV-case series.

REPRODUCIBILITY OF MODIFIED WALDENSTRÖM CLASSIFICATION IN PERTHES DISEASE

Objective:

The purpose of our study is to evaluate intraobserver and interobserver reliability of modified Waldenström classification system for Legg-Calvé-Perthes disease and assess the influence of the professional’s area of expertise in the assessment.

Methods:

Twelve evaluators assessed 40 pairs of pelvic radiographs of patients with Legg-Calvé-Perthes disease. After two weeks, a new evaluation was performed by the same evaluators. Kappa and Kendall’s W indexes were used to evaluate both intraobserver and interobserver reliability and determine the influence of the evaluators’ experience and area of expertise.

Results:

The average intraobserver kappa value was 0.394, with a reasonable agreement level. The interobserver Kappa value was 0.243 in the first evaluation (95% CI, 0.227-0.259 and p < 0.0001) and 0.245 in the second evaluation (95% CI, 0.229-0.260 and p < 0.0001). The Kendall’s W values obtained for pediatric orthopedists, radiologists and resident physicians were 0.686, 0.630 and 0.529 (p < 0.0001), respectively. Conclusion: The modified Waldenström classification presented both moderate and reasonable levels of intraobserver agreement, and reasonable level of interobserver agreement. The evaluators’ degree of experience and area of expertise influenced the concordance level found. Level of Evidence II, Diagnostic Studies - Investigating a Diagnostic Test.

Reproducibility of Radiographic Measurements Made in the Active Stages of Legg-Calvé-Perthes Disease: Evaluation of a Prognostic Indicator and an Interim Outcome Measure

BACKGROUND

Deformity index (DI) and extrusion index (EI) are 2 radiographic methods currently used to quantify femoral head deformity in the active stages of Legg-Calvé-Perthes disease. This study aimed to quantify the interobserver reproducibility of the 2 methods using a large, international group of pediatric orthopaedic surgeons with diverse clinical experience.

METHODS

Radiographs of patients (age 6 to 11 y at time of diagnosis) prospectively enrolled in an international multicenter-cohort study, were measured by members of our study group. For each radiograph, the raters independently assessed EI (n=33 cases) and DI (n=32 cases), along with the rater's subjective assessment of the extent of hip deformity (ie, none, mild, moderate, or severe). Reliability analysis was conducted using intraclass correlation coefficient (ICC) and κ techniques.

RESULTS

The ICC for EI on the affected side was 0.68 (95% confidence interval: 0.57-0.79). The calculated DI ICC was 0.53 (95% confidence interval: 0.41-0.68). Subjectively, an average of 68±3.5% of surgeons agreed on the subjective description of each patient's femoral head deformity.

CONCLUSIONS

EI is measured with a reasonably high rate of correlation among surgeons from disparate backgrounds. Agreement is lower among the same group of surgeons when the more complex DI is used. DI is most useful when utilized by a small number of experienced observers in a research setting, whereas EI may have better clinical applicability.

LEVEL OF EVIDENCE

Level III-reliability study.

Legg-Calvé-Perthes' disease. Congruent aspherity caused by physeal injury

INTRODUCTION

Perthes disease often produces a congruent nonspherical coxa. The most widely accepted cause is initial bone collapse, but some authors refer to physeal injury as the cause of this deformity. We analyze this elliptical process in cases of congruent nonspherical Perthes.

METHODS

Retrospective case-control study of 49 unilateral class III-IV Perthes cases that were not operated on. Results were compared with 49 healthy contralateral hips. The following radiological variables were determined both in AP and lateral projection, and at 4 points in time of the disease: ovalization index (OI), arthrotrochanteric distance, intraphysial angle, physeal narrowing, presence of double epiphyseal reosification nucleus, physeal length and Reimers index.

RESULTS

The initial OI was 1.7 in the early reosification phase and final OI was 2.07 at physeal closure. The OI in the control cases was invariably 1.4. There was a direct relation between a high index and the initial appearance of a double epiphyseal ossification nucleus, asymmetric physeal effacement and the increase of the intraphyseal angle in both radiographic projections.

CONCLUSIONS

The elliptical process of the femoral head occurs progressively throughout the disease and not only during bone collapse. It starts in the reosification phase and ends when growth stops. The initial risk signs found were the appearance of the double nucleus of reosification, the progressive angulation of the physis and the progressive increase in the rate of ovalization.

Reliability of the modified lateral pillar classification for Legg Calvé Perthes disease performed by a large group of international paediatric orthopaedic surgeons

PURPOSE

The modified lateral pillar classification (mLPC) is used for prognostication in the fragmentation stage of Legg Calvé Perthes disease. Previous reliability assessments of mLPC range from fair to good agreement when evaluated by a small number of observers with pre-selected radiographs. The purpose of this study was to determine the inter-observer and intra-observer reliability of mLPC performed by a group of international paediatric orthopaedic surgeons. Surgeons self-selected the radiograph for mLPC assessment, as would be done clinically.

METHODS

In total, 40 Perthes cases with serial radiographs were selected. For each case, 26 surgeons independently selected a radiograph and assigned mLPC and 21 raters re-evaluated the same 40 cases to establish intra-observer reliability. Rater performance was determined through surgeon consensus using the mode mLPC as 'gold standard'. Inter-observer and intra-observer reliability data were analysed using weighted kappa statistics.

RESULTS

The weighted kappa for inter-observer correlation for mLPC was 0.64 (95% confidence interval: 0.55 to 0.74) and was 0.82 (range: 0.35 to 0.99) for intra-observer correlation. Individual surgeon's overall performance varied from 48% to 88% agreement. Surgeon mLPC performance was not influenced by years of experience (p = 0.51). Radiograph selection did not influence gold standard assignment of mLPC. There was greater agreement on cases of mild B hips and severe C hips.

CONCLUSIONS

mLPC has low good inter-observer agreement when performed by a large number of surgeons with varied experience. Surgeons frequently chose different radiographs, with no impact on mLPC agreement. Further refinement is needed to help differentiate hips on the border of group B and C.

LEVEL OF EVIDENCE

III.

Intra- and inter-observer reliability of Laredo classification system in Legg-Calvé-Perthes Disease

The purpose of the current study was to investigate intra- and inter-observer reliability of arthrographic Laredo classification system in Perthes disease. Forty-seven patients were included in this cross-sectional descriptive study. Patients' age, gender, physical findings and hip arthrographs were collected from hospital medical records. Two different sets of power point slides were prepared in which the order of cases was randomized and blinded. Observers were divided into three groups according to their surgical experience (9 residents, 10 seniors, 10 pediatric orthopedists), and they assessed two times 1 month's intervals. Statistical analysis was performed by using the SPSS v21. Inter- and intra-observer reliabilities were calculated using intra-class correlation coefficient, weighted kappa and percentage agreement. Percentage agreement of Laredo classification was about 50% for all groups (residents, seniors and pediatric orthopedists); intra-observer reliabilities were excellent, excellent and fair, respectively. Inter-observer reliability of Laredo classification for each set was found to be excellent for all groups. Length of experience did not correlated significantly with the level of intra-observer agreement. As a conclusion, our results showed that Laredo's arthrographic classification system's intra-observer reliability is at least at a fair level and inter-observer reliability is at an excellent level. We believe that this classification system is valuable for an orthopedic surgeon who deals with the treatment of Perthes disease.

Proximal Femoral Growth Modification: Effect of Screw, Plate, and Drill on Asymmetric Growth of the Hip

BACKGROUND

Guided growth has long been used in the lower extremities but has not been applied to varus or valgus deformity in the hip, as may occur in children with cerebral palsy or developmental dysplasia of the hip. The purpose of this study was to determine if screw, plate, or drilling techniques decreased the femoral neck-shaft angle (NSA) and articular trochanteric disease (ATD), as well as describe growth plate structural changes with each method.

METHODS

Twelve 8-week-old lambs underwent proximal femoral hemiepiphysiodesis (IACUC approved) using either a screw (n=4), plate (n=4), or drilling procedure (n=4). Postoperative time was 6 months. Radiographs taken after limb harvest were used to measure NSA and ATD. Differences between treated and control sides were determined by 1-tailed paired t tests and Bonferroni (α=0.05/3). Histology was obtained for 1 limb pair per group. Proximal femurs were cut in midcoronal plane and the longitudinal growth plates were examined for structural changes.

RESULTS

The mean NSA measured 7 degrees less than controls in this model using the screw technique, and this difference was statistically significant. Differences between the control and the treated groups did not reach statistical significance for either the plate or the drill group. Differences in ATD were not statistically significant, although there was a trend for larger ATD measurements using the screw technique. Histologically, physeal changes were observed on the operative sides in screw and plate specimens, but not drill specimens, compared with contralateral sham control. The screw specimen exhibited the most severe changes, with growth plate closure over half the section. The plate specimen showed focal loss of the physis across the section, but with no evidence of closure.

CONCLUSIONS

This study builds on previous work that indicates screw hemiepiphysiodesis can effectively alter the shape of the proximal femur, and result in a lower neck-shaft ankle (or lesser valgus). This study suggests that implantation of a screw is likely to be more effective than a plate or drilling procedure in decreasing the NSA in skeletally immature hips.

CLINICAL SIGNIFICANCE

If further preclinical, and later clinical, studies demonstrate reproducible efficacy, guided growth of the proximal femur may eventually become a viable option for treatment or prevention of hip deformity in select patients.

Radiographic classifications in Perthes disease

Background and purpose - Different radiographic classifications have been proposed for prediction of outcome in Perthes disease. We assessed whether the modified lateral pillar classification would provide more reliable interobserver agreement and prognostic value compared with the original lateral pillar classification and the Catterall classification. Patients and methods - 42 patients (38 boys) with Perthes disease were included in the interobserver study. Their mean age at diagnosis was 6.5 (3-11) years. 5 observers classified the radiographs in 2 separate sessions according to the Catterall classification, the original and the modified lateral pillar classifications. Interobserver agreement was analysed using weighted kappa statistics. We assessed the associations between the classifications and femoral head sphericity at 5-year follow-up in 37 non-operatively treated patients in a crosstable analysis (Gamma statistics for ordinal variables, γ). Results - The original lateral pillar and Catterall classifications showed moderate interobserver agreement (kappa 0.49 and 0.43, respectively) while the modified lateral pillar classification had fair agreement (kappa 0.40). The original lateral pillar classification was strongly associated with the 5-year radiographic outcome, with a mean γ correlation coefficient of 0.75 (95% CI: 0.61-0.95) among the 5 observers. The modified lateral pillar and Catterall classifications showed moderate associations (mean γ correlation coefficient 0.55 [95% CI: 0.38-0.66] and 0.64 [95% CI: 0.57-0.72], respectively). Interpretation - The Catterall classification and the original lateral pillar classification had sufficient interobserver agreement and association to late radiographic outcome to be suitable for clinical use. Adding the borderline B/C group did not increase the interobserver agreement or prognostic value of the original lateral pillar classification.

Biomechanical considerations in slipped capital femoral epiphysis and insights into prophylactic fixation

PURPOSE

Slipped capital femoral epiphysis (SCFE) is a deformity of the proximal femur secondary to widened and unstable physis. In stabilising the slip, gold standard treatments stop growth and involve premature physeal closure, which prevents the remodelling of the acquired deformity and creates a leg length discrepancy that may be significant in younger patients.

METHODS

We measured the impact of placing threaded screws across the proximal femoral physis by measuring the centre-trochanteric distance (CTD) and articulo-trochanteric distance (ATD) in participants with or without prophylactic fixation. We then compared the mechanical performance of static (stainless and titanium cannulated Synthes screws) and potentially growing implants (Synthes SCFE screw and Pega Medical Free Gliding screw) in a validated synthetic bone model.

RESULTS

In the review of 30 non-fixed and 60 fixated hips over a mean follow-up of 1.9 years, we have noted a significant difference in pre/post CTD and ATD, as well as the change in CTD and ATD over time. In the biomechanical study, the newer implants allowing growth (Synthes SCFE screw and Pega Medical Free Gliding screw) were both shown to be at least non-inferior.

CONCLUSIONS

The primary deformity of a SCFE in itself alters hip mechanics. Also, as confirmed in this study, there is a secondary deformity that is created by static fixation and relative trochanteric overgrowth. To help remodel mild deformities and prevent secondary trochanteric overgrowth, growing implants seem to be non-inferior to the more standard means of fixation in static testing.

Protocol for a randomised control trial of bisphosphonate (zoledronic acid) treatment in childhood femoral head avascular necrosis due to Perthes disease

INTRODUCTION

Perthes disease (PD) is an idiopathic disorder presenting with avascular necrosis to the femoral head, which frequently results in flattening. Long-term function is directly related to the subsequent femoral head sphericity. Current treatment includes mechanical modalities and surgical procedures, which are therapeutic but are not uniformly able to prevent collapse. The use of the nitrogen-containing bisphosphonate zoledronic acid (ZA) to inhibit osteoclastic bone resorption is aimed at preserving femoral head strength, reducing collapse and thus maintaining shape. The proposed multicentre, prospective, randomised controlled trial intends to evaluate the efficacy of ZA treatment in PD.

METHODS AND ANALYSIS

An open-label randomised control trial recruiting 100 children (50 each treatment arm) 5 to 16 years old with unilateral PD. Subjects are randomly assigned to either (a) ZA and standard care or (b) Standard care. The primary outcome measure is deformity index (DI), a radiographic parameter of femoral head roundness assessed at 24 months, following 12 months of ZA treatment (3-monthly doses of ZA 0.025 mg/kg at baseline, 3, 6, 9 and 12 months) plus 12 months observation (group A) or 24 months of observation (group B). Secondary outcome measures are femoral head subluxation, Faces Pain scale, Harris hip score and quality of life. Assessments are made at baseline, 3 monthly during the first year of follow-up and then 6 monthly, until the 24th month.

ETHICS AND DISSEMINATION

The study commenced following the written approval from the Human Research Ethics Committee. Safety considerations regarding the effects of ZA are monitored which include the subject's symptomatology, mineral status, bone mass and turnover activity, and metaphyseal modelling. Data handling plan requires that all documents, clinical information, biological samples and investigation results will be held in strict confidence by study investigators to preserve its safety and confidentiality.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials ACTRN12610000407099, pre-results.

Periacetabular osteotomy: validation of intraoperative fluoroscopic monitoring of acetabular orientation

During periacetabular osteotomy (PAO) the acetabulum is reorientated and the correction monitored by one or more anteroposterior pelvic radiographs. Obtaining these images is time consuming and requires additional technical and personal resources. Such disadvantages could be overcome with the use of fluoroscopy. However, information obtained from fluoroscopy should have the same quality when compared to standard pelvic radiography. Our purpose was to define a suitable fluoroscopy setup and compare the information obtained from the fluoroscopic images to that obtained from a traditional anteroposterior pelvic radiograph. In a consecutive series of 22 patients the acetabular fragment was monitored by a defined intraoperative fluoroscopy setup in addition to a pelvic radiograph. The images were analyzed in random order utilizing common parameters to judge the quality of acetabular orientation. Agreement between the two images was assessed using kappa statistics and compared to the intra-observer reliability obtained from an independent experienced hip surgeon reading the same set of pelvic radiographs on two occasions. In 5 patients the radiation exposure during both fluoroscopy and standard AP pelvic radiography was measured and compared. Agreement of angular measurements of acetabular coverage and version as well as qualitative parameters of acetabular orientation and position between fluoroscopy and pelvic radiographs was at least equal to the intra-observer agreement of an independent experienced hip surgeon reviewing the pelvic radiographs alone. Significantly less radiation exposure was recorded with the use of fluoroscopy when compared to traditional pelvic radiography. We conclude that the use of intraoperative pelvic radiographs during PAO procedures can be replaced by fluoroscopy without quality impairment.

Development of gait performance and dynamic hip and knee joint loading after containment improving surgery in patients with Legg-Calvé-Perthes disease

Current surgery outcome evaluations in patients with Legg-Calvé-Perthes disease (LCPD) are usually based on static radiological changes. The aim of the present study was to assess the development of characteristic gait parameters and passive hip range of motion (ROM) measurements during the postoperative period up to healed stage of the femoral head represented by Stulberg classification. Twelve children (10 male, 2 female) with unilateral diagnosis of LCPD and 19 healthy control subjects at the same age participated in this prospective longitudinal study. Instrumented gait analysis was performed preoperatively, 13.4 (±1.7), and 28.0 (±4.4) months postoperatively. At final follow-up, the mean leg length of the involved side was reduced by 1.10 (±0.53)cm compared to the non-involved side. In addition, a significant reduction in maximum knee flexion (-26%, p=0.037) and knee flexion/extension ROM (-26%, p=0.017) in stance was still present in the patient group compared to controls indicating a "stiff knee gait pattern". In contrast, the sagittal plane hip parameters, the ipsilateral trunk lean toward the involved stance limb, and the knee and hip joint loading during gait normalized during the postoperative period. The results of the present study should motivate further exploration if patients with LCPD stiffen their knees to compensate for leg length discrepancy. Besides the standard radiological evaluation of the surgery outcome, instrumented gait analysis is a valuable method of recording functional deficits and early recognition of the need for physiotherapeutic treatment or insole supply in patients with LCPD.

Activity Level and Severity of Dysplasia Predict Age at Bernese Periacetabular Osteotomy for Symptomatic Hip Dysplasia

BACKGROUND

The age when patients present for treatment of symptomatic developmental dysplasia of the hip with periacetabular osteotomy (PAO) varies widely. Modifiable factors influencing age at surgery include preexisting activity level and body mass index (BMI). The severity of the hip dysplasia has also been implicated as a factor influencing the age at arthritis onset. The purpose of this study was to determine whether activity level, BMI, and severity of dysplasia are independent predictors of age of presentation for PAO.

METHODS

A retrospective, institutional review board-approved review of prospectively collected data from a multicenter study group identified 708 PAOs performed for developmental dysplasia of the hip. Demographic factors that were considered in the analysis included age at surgery, BMI, history of hip disorder or treatment, and duration of symptoms. The severity of the developmental dysplasia of the hip was assessed by radiographic measurement of the lateral and anterior center-edge angles and acetabular inclination. Activity level was assessed with the University of California, Los Angeles (UCLA) activity score. Spearman correlations and t tests were used for univariable analysis. Multivariable regression analysis using generalized estimating equations was applied to determine independent predictors of age at PAO.

RESULTS

Univariable analysis indicated that age at presentation for treatment of PAO correlated with the lateral and anterior center-edge angles (p < 0.001), UCLA score (p < 0.001), and BMI (p = 0.04). Since the lateral and anterior center-edge angles were similarly correlated (Spearman rho = 0.61, p < 0.001), the lateral center-edge angle alone was used to classify the severity of the developmental dysplasia of the hip. Multivariable linear regression confirmed that a high UCLA score and severe hip dysplasia were independent predictors of age at PAO (p < 0.001).

CONCLUSIONS

A high activity level and severe dysplasia lead to the development of symptoms and presentation for PAO at significantly younger ages. The combination of these two factors has an even greater effect on decreasing the age at presentation for hip-preserving surgery. An increased BMI was not independently associated with a younger age at surgery. Modifying activity level may be beneficial in terms of delaying the onset of symptoms from developmental dysplasia of the hip.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The outcome and prognostic factors in children with bilateral Perthes' disease: a prospective study of 40 children with follow-up over five years

AIMS

The aims of this study were to describe the course of non-operatively managed, bilateral Perthes' disease, and to determine specific prognostic factors for the radiographic and clinical outcome.

PATIENTS AND METHODS

We identified 40 children with a mean age of 5.9 years (1.8 to 13.5), who were managed non-operatively for bilateral Perthes' disease from our prospective, multicentre study of this condition, which included all children in Norway who were diagnosed with Perthes' disease in the five-year period between 1996 and 2000. All children were followed up for five years. The hips were classified according to the Catterall classification. A modified three-group Stulberg classification was used as an outcome measure, with a spherical femoral head being defined as a good outcome, an oval head as fair, and a flat femoral head as a poor outcome.

RESULTS

Concurrent, simultaneous bilateral Perthes' disease was seen in 23 children and 17 had the sequential onset of bilateral disease. The mean delay in onset for the second hip in the latter group was 1.9 years (0.3 to 5.5). The five-year radiographic outcome was good in 30 (39%), fair in 25 (33%) and poor in 21 (28%) of the hips. The strongest predictors of poor outcome were > 50% necrosis of the femoral head, with odds ratio (OR) 19.6, and age at diagnosis > 6 years (OR 3.3). Other risk factors for poor outcome were the timing of the onset of disease, where children with the sequential onset of bilateral disease had a higher risk than those with the concurrent onset of bilateral disease (p = 0.021, chi-squared test). Following a diagnosis of Perthes' disease in one hip, there was a 5% chance of developing it in the contralateral hip.

CONCLUSION

These results imply that we need to distinguish between children with concurrent onset and those with sequential onset of bilateral Perthes' disease, as the outcomes may be different. This has not been previously described. Children with concurrent onset of bilateral disease had a similar outcome to our previous series of those with unilateral disease, whereas children with sequential onset of bilateral disease had a worse prognosis. The increased risk of developing Perthes' disease in the contralateral hip in those with unilateral disease is important information for the child and parents.

Assessment of lateral subluxation in Legg-Calvé-Perthes disease: a time-sequential study of magnetic resonance imaging and plain radiography

Lateral subluxation of the femoral head is one of the poor prognostic factors of Legg-Calvé-Perthes disease. The aim of this study was to investigate the cause of lateral subluxation of the femoral head on the basis of the changes over time on MRI. Twenty-four patients with unilateral Legg-Calvé-Perthes disease were analyzed retrospectively. Lateral subluxation was measured as the tear drop distance on radiographs. We focused on joint fluid, medial articular cartilage thickening, and abnormal lesion on MRI. Lateral subluxation continued significantly in patients with poor results. Among the MRI findings, the presence of an abnormal lesion was associated significantly with the continuous lateral subluxation.

High reliability in digital planning of medial opening wedge high tibial osteotomy, using Miniaci's method

PURPOSE

Pre-operative planning is essential in high tibial osteotomy (HTO). Miniaci's method employs Mikulicz's weight-bearing line and is advantageous because the point of mechanical loading is related to the known degenerative condition of the knee. Miniaci's geometrical method has been modified for an opening wedge and described for use with a digital picture archiving and communications system viewer. Reliability for this method was hypothesised to be equivalent to published reliability for landmark-based commercial software and independent of observer experience.

METHODS

Twenty-four patients awaiting HTO had standardised long-leg radiographs. Mikulicz's weight-bearing line was projected through the lateral compartment of the knee at Fujisawa's point. The correction angle was generated at the hinge point subtending the current and proposed ankle centres. The opening wedge was plotted to measure an opening distance. Observations were recorded twice by three observers. Agreement was reported as intraclass correlation coefficients with 95 % confidence intervals.

RESULTS

Intra-rater agreement was excellent for the correction angle (0.965-0.985) and opening distance (0.928-0.980). If no set hinge point was used, then the inter-rater reliability was 0.986 for the correction angle and 0.984 for the opening distance. There was no discernible pattern demonstrating improved reliability from the experienced observer.

CONCLUSIONS

Reliability is comparable to commercially based landmark software and independent of observer experience. This makes such geometrical pre-operative planning accessible to surgeons who perform HTO with insufficient frequency to justify the investment in commercial software.

LEVEL OF EVIDENCE

Diagnostic study, Level II.

Interobserver and intraobserver reliability of the modified Waldenström classification system for staging of Legg-Calvé-Perthes disease

BACKGROUND

The absence of a reliable classification system for Legg-Calvé-Perthes disease has contributed to difficulty in establishing consistent management strategies and in interpreting outcome studies. The purpose of this study was to assess interobserver and intraobserver reliability of the modified Waldenström classification system among a large and diverse group of pediatric orthopaedic surgeons.

METHODS

Twenty surgeons independently completed the first two rounds of staging: two assessments of forty deidentified radiographs of patients with Legg-Calvé-Perthes disease in various stages. Ten of the twenty surgeons completed another two rounds of staging after the addition of a second pair of radiographs in sequence. Kappa values were calculated within and between each of the rounds.

RESULTS

Interobserver kappa values for the classification for surveys 1, 2, 3, and 4 were 0.81, 0.82, 0.76, and 0.80, respectively (with 0.61 to 0.80 considered substantial agreement and 0.81 to 1.0, nearly perfect agreement). Intraobserver agreement for the classification was an average of 0.88 (range, 0.77 to 0.96) between surveys 1 and 2 and an average of 0.87 (range, 0.81 to 0.94) between surveys 3 and 4.

CONCLUSIONS

The modified Waldenström classification system for staging of Legg-Calvé-Perthes disease demonstrated substantial to almost perfect agreement between and within observers across multiple rounds of study. In doing so, the results of this study provide a foundation for future validation studies, in which the classification stage will be associated with clinical outcomes.

The acetabulum in Perthes' disease: inter-observer agreement and reliability of radiographic measurements

BACKGROUND AND PURPOSE

Perthes' disease leads to radiographic changes in both the femoral head and the acetabulum. We investigated the inter-observer agreement and reliability of 4 radiographic measurements assessing the acetabular changes.

PATIENTS AND METHODS

We included 123 children with unilateral involvement, femoral head necrosis of more than 50%, and age at diagnosis of 6 years or older. Radiographs were taken at onset, and 1 year and 5 years after diagnosis. Sharp's angle, acetabular depth-width ratio (ADR), lateral acetabular inclination (LAI), and acetabular retroversion (ischial spine sign, ISS) were measured by 3 observers. Before measuring, 2 of the observers had a consensus meeting.

RESULTS

We found good agreement and moderate to excellent reliability for Sharp's angle for all observers (intra-class correlation coefficient (ICC) > 0.80 with consensus, ICC = 0.46-0.57 without consensus). There was good agreement and substantial reliability for ADR between the observers who had had a consensus meeting (ICC = 0.62-0.89). Low levels of agreement and poor reliability were found for observers who had not had a consensus meeting. LAI showed fair agreement throughout the course of the disease (kappa = 0.28-0.52). The agreement between observations for ISS ranged from fair to good (kappa = 0.20-0.76).

INTERPRETATION

Sharp's angle showed the highest reliability and agreement throughout the course of the disease. ADR was only reliable and showed good agreement between the observers when landmarks were clarified before measuring the radiographs. Thus, we recommend both parameters in clinical practice, provided a consensus is established for ADR. The observations for LAI had only fair agreement and ISS showed inconclusive agreement in our study. Thus, LAI and ISS can hardly be recommended in clinical practice.

An assessment of intra- and interobserver agreement of reporting orthopaedic findings on presale radiographs of Thoroughbred yearlings

REASONS FOR PERFORMING STUDY

Radiography is commonly used in clinical practice but agreement of reporting of radiographically detected orthopaedic findings in horses has rarely been studied.

OBJECTIVES

To assess agreement within and between observers for reporting of orthopaedic findings on presale radiographs of Thoroughbred yearlings.

STUDY DESIGN

Retrospective analysis of archived radiographs.

METHODS

Four veterinary radiology specialists each twice examined 167 sets of radiographs for orthopaedic findings in the fore feet, fore and hind fetlocks, carpi, tarsi and stifles. There were 27 findings analysed for agreement. Kappa statistic (κ), percentage of positive agreement (Ppos) and percentage of negative agreement are reported.

RESULTS

An excellent percentage of negative agreement was observed for all findings, with the exception of regular vascular channels of the proximal sesamoid bones. Ppos and κ results were variable. The presence of extra carpal bones, osseous cyst-like lesions of the ulnar carpal bone, sagittal ridge defects of the third metacarpus, fracture of the fore and hind proximal sesamoid bones, regular vascular channels in the hind proximal sesamoids, osteochondrosis lesions of the distal intermediate ridge and/or medial malleoli of the tibia, and osseous cyst-like lesions in the medial femoral condyle was consistently observed with an intra- and interagreement κ≥0.5 and Ppos≥50%. Lucency within the proximal sesamoids consistently had an observed intra- and interagreement κ<0.4 and Ppos<40%.

CONCLUSIONS

Observation of orthopaedic findings on yearling repository radiographs showed generally excellent agreement on the absence of findings, but variable agreement on the presence of findings. Agreement was good for larger and easy to categorise radiographic findings. More accurate definitions and training need to be developed to improve agreement within and between observers for orthopaedic findings with poor or fair to good agreement.

Intra- and interdisciplinary agreement in the rating of acromioclavicular joint dislocations

BACKGROUND

Acromioclavicular (AC) joint dislocation is a common injury observed and treated by physicians from several disciplines; proper classification and communication of the diagnosis between physicians is essential to manage injuries properly. This study assessed inter- and intradepartmental agreement in the rating of AC joint dislocations and compared departments of orthopedic surgery, musculoskeletal (MSK) radiology, and emergency medicine (EM).

METHODS

Fifty radiographs indicating a random distribution of AC dislocations (Rockwood types I, II, III, and V) were sent to 25 resident, fellow, and attending physicians; the study group consisted of orthopedic surgeons (n = 9), MSK radiologists (n = 7), and EM physicians (n = 9). Dislocations were rated by physicians using the Rockwood classification (excluding type IV) and rating agreement was derived using the multirater κ statistic.

RESULTS

Moderate rating agreement was found among orthopedic surgeons (κ = 0.5147), which was higher than among radiologists (κ = 0.3628) or EM physicians (κ = 0.1894). Interdisciplinary rating agreement was highest between orthopedic surgeons and MSK radiologists and lowest between MSK radiologists and EM physicians. Attending orthopedic surgeons showed the highest rating agreement (κ = 0.5167) compared with attending MSK radiologists (κ = 0.3585) and attending EM physicians (κ = 0.2612). In-training orthopedic surgeons had higher rating agreement (κ = 0.4918) than in-training MSK radiologists (κ = 0.4218) and in-training EM physicians (κ = 0.1410).

DISCUSSION

Orthopedic surgeons exhibited the highest intradepartmental rating agreement in assessing AC joint injuries, but interdepartmental rating agreement was low. It is unclear if low interdepartmental rating agreement reflects classification or training weaknesses; recognition of these differences may help develop a more standardized education for physicians to improve the management of AC joint injuries.

CONCLUSIONS

Interdisciplinary rating agreement of AC joint injuries is low. Further study may help improve education and communication about AC joint injuries among physicians.

Reliability and stability of three common classifications for Legg-Calvé-Perthes disease

BACKGROUND

To predict the course of Legg-Calvé-Perthes disease (LCPD) and select between treatment options in the early stages, it is critical to have a reliable predictive classification.

QUESTIONS/PURPOSES

We examined the reliability and stability of three common classification systems for LCPD.

METHODS

We identified 69 patients with LCPD, who had hip radiographs taken more than twice after the initial presentation with at least a 3-month interval. The Herring lateral pillar, Catterall, and Salter-Thompson classifications were evaluated in terms of reliability and stability. The inter- and intrarater reliability of the classification systems was determined by three orthopaedic surgeons using intraclass correlation coefficients (ICCs). To evaluate the stability of the classification systems, the percentage agreement and ICCs among the initial rating, rating when entering fragmentation, and final rating were used.

RESULTS

The interrater reliability was highest in Herring lateral pillar classification (ICC, 0.885) followed by the Catterall and Salter-Thompson classifications (ICC, 0.802 and 0.702, respectively). The percentage agreement and ICC between the initial and final rating were, respectively, 55% and 0.491 for the Herring classification and 48% and 0.378 for the Catterall classification.

CONCLUSIONS

Our data show the highest reliability of the classification of Herring et al. However, more than 40% of the hip radiographs at the initial presentation, and in particular, most of Herring Group A patients, were upgraded. Therefore, for patients older than 8 years old and graded as Herring Group A initially, surgeons should keep the possibility of surgical treatment in mind.

Classification of distal radius fractures in children: good inter- and intraobserver reliability, which improves with clinical experience

Background

We wanted to test the reliability of a commonly used classification of distal radius fractures in children.

Methods

105 consecutive fractures of the distal radius in children were rated on two occasions three months apart by 3 groups of doctors; 4 junior registrars, 4 senior registrars and 4 orthopedic consultants. The fractures were classified as buckle, greenstick, complete or physeal. Kappa statistics were used to analyze inter- and intraobserver reliability.

Results

The kappa value for interobserver agreement at the first reading was 0.59 for the junior registrars, 0.63 for the senior registrars and 0.66 for the consultants. The mean kappa value for intraobserver reliability was 0.79 for the senior registrars, 0.74 for the consultants and 0.66 for the junior registrars.

Conclusions

We conclude that the classification tested in this study is reliable and reproducible when applied by raters experienced in fracture management. The reliability varies according to the experience of the raters. Experienced raters can verify the classification, and avoid unnecessary follow-up appointments.

Comparison between conservative and surgical treatment in Perthes disease

INTRODUCTION

The purpose of this study was to compare the results of conservative and surgical treatment in a homogeneous group constituted by patients between 6 and 8 years of age at onset of the Perthes disease with Herring B involvement.

METHODS

Twenty-seven hips of 25 patients were evaluated radiologically and clinically. Patients were divided into two groups in terms of treatment type. In group I [16 hips of 14 patients], hips were treated conservatively using Thomas splints. The mean follow-up period was 21.5 (10-25) years. In group II [11 patients], hips were treated surgically using femoral osteotomy. The mean follow-up period was 14.3 (8-20) years.

RESULTS

There was no statistically significant difference between the groups in terms of Stulberg classification, but surgically treated patients had more varus angle, more shortening, and more trochanteric overgrowth compared with the braced group.

CONCLUSION

Non-surgical treatment with a brace is a reliable alternative to surgical treatment in Perthes disease between 6 and 8 years of age at onset with Herring B involvement. However, we could not know whether the good results were influenced by the brace or stemmed from having good prognosis of these patients.

Residual hip dysplasia as a risk factor for osteoarthritis in 45 years follow-up of late-detected hip dislocation

PURPOSE

The aim of the study was to assess the role of residual hip dysplasia as a risk factor for osteoarthritis (OA) in developmental dysplasia of the hip (DDH).

METHODS

Fifty-one patients (60 hips) with late-detected DDH were studied. Reduction had been performed at a mean age of 19 months (range 4-65 months). On radiographs at age 8-10 years, at skeletal maturity, and at long-term follow-up, femoral head coverage was assessed using the migration percentage (MP) and centre-edge (CE) angle. OA was diagnosed if the minimum joint space width of the upper part of the joint was <2.0 mm.

RESULTS

The mean age at the last follow-up was 45 years (range 43-49 years) in patients who had not undergone total hip replacement (THR). Ten patients had developed OA and eight of them had undergone THR at a mean age of 40 years (range 32-47 years). There was a clear association between OA and residual hip dysplasia. At the last follow-up, 37 hips had normal CE angles (20° or higher) and OA had developed in only two of them (5%; 95% confidence interval [CI] 1-18%). Hip dysplasia without subluxation (CE angle 10-19°) was seen in 18 hips, of which 14 hips had good outcome and four had OA (22%; 95% CI 6-48%). Subluxation occurred in five hips, of which one had a good long-term outcome and four had OA (80%; 95% CI 28-99%). In patients without late reconstructive surgery, MP increased from the age of 10 years to skeletal maturity; thereafter, no significant change occurred. The CE angle did not change significantly between the age of 10 years and the last follow-up.

CONCLUSION

Hip dysplasia without subluxation has a relatively good long-term prognosis. Subluxation is a risk factor for osteoarthritis. Thus, children with MP above 33% and CE angle under 10° should be evaluated for reconstructive surgery in order to improve the long-term outcome.

Long-term follow-up of a patient cohort with Legg-Calvé-Perthes disease

The purpose of this study was to evaluate prognostic risk factors related to a poor radiological outcome. The study consisted of 74 patients with Legg-Calvé-Perthes disease treated using a Thomas splint. The modified Herring lateral pillar classification and the reviewed Stulberg classification system were applied. A significant correlation between the Herring group and Stulberg was found (P=0.03). There was a significant correlation between age at onset of the disease and Stulberg outcome (P=0.05). The Herring classification correlated to the Stulberg outcome. An age of 7 years or more at onset was considered as a risk factor for a poor Stulberg outcome.

Pathophysiology, classifications, and natural history of Perthes disease

Since the original reports of Legg-Calvé-Perthes disease (LCPD), much research effort has been undertaken to improve understanding of this idiopathic hip disorder. This article focuses on the current knowledge of the pathophysiology, classifications, and natural history of LCPD. Although the cause of LCPD remains largely unknown, some insight has been gained on its pathophysiology through experimental studies using animal models of ischemic necrosis. The few available clinical studies on the natural history of LCPD suggest that femoral head deformity is well tolerated in short and intermediate terms, but 50% of patients develop disabling arthritis in the sixth decade of life.

Does trochanteric transfer eliminate the Trendelenburg sign in adults?

BACKGROUND

Premature closure of the proximal femoral growth plate results in coxa brevis, which usually is associated with insufficiency of the hip abductors. Distal and lateral transfer of the greater trochanter sometimes is recommended to correct this problem. Most of what is known arises from studies of children and adolescents.

QUESTIONS/PURPOSES

We asked whether this procedure in adults with coxa brevis would eliminate hip abductor insufficiency and would improve their hip function based on the Harris hip score (HHS).

PATIENTS AND METHODS

We prospectively followed 11 patients, aged 19 to 55 years (mean, 40 years) who had distal and lateral trochanteric transfer. All patients had pain and a positive Trendelenburg test before surgery. This test was performed at the latest followup by three observers and the interobserver reliability was determined by the kappa coefficient. The HHS was obtained before surgery and at the latest followup. The minimum followup was 25 months (mean, 52 months; range, 25-77 months).

RESULTS

Insufficiency of the hip abductors was eliminated in seven (according to two observers) and eight (according to one observer) of the 11 patients after surgery; the kappa coefficient ranged from 0.79 to 1.0. The mean HHS improved from 64 points preoperatively to 76 points at the final followup. The two patients with preexisting severe osteoarthritis of the hip had the worst final scores and persisted with a positive Trendelenburg test at the final followup.

CONCLUSIONS

Distal and lateral transfer of the greater trochanter can eliminate insufficiency of the hip abductors and improve joint function in adult patients with coxa brevis and we believe should be considered for patients without severe osteoarthritis of the hip.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Imaging in Legg-Calvé-Perthes disease

Imaging in Legg-Calvé-Perthes disease should help assess the severity and the stage of the disease, detect severe forms earlier, and provide guidance to therapy. However, due to the complexity of the disease, not all examinations can be performed at the same time with the same goals. The scope of this work is to provide an overview of all imaging techniques available today, and to help understand when to use a particular examination. Advantages and limitations of plain radiographs, bone scintigraphy, magnetic resonance imaging, arthrography, computed tomography, and ultrasonography are identified.

[Legg-Calvé-Perthes disease]

BACKGROUND

Legg-Calvé-Perthes disease is characterized by avascular necrosis of the head of the femur. This article deals with the epidemiology, possible causes, treatment and prognostic factors connected with the disease.

MATERIAL AND METHOD

The article is based on a non-systematic literature search and own clinical practice, with special emphasis on a Norwegian countrywide study of children with Legg-Calvé-Perthes disease.

RESULTS

The incidence of Legg-Calvé-Perthes disease varies in different countries and regions. Those who are older than six years at the time of diagnosis and have over 50% femoral head necrosis have a worse prognosis than younger children where the necrosis is less extensive. Treatment has been discussed extensively over the past 100 years, and still varies considerably. The Norwegian countrywide investigation showed that the results in children who were over six years at the time of diagnosis and had more than 50% femoral head necrosis were significantly better after varus femoral osteotomy than after physiotherapy or orthosis. This agrees with the only other prospective study that has been published.

INTERPRETATION

Operative treatment should be considered in children who are six years old or older and have over 50% femoral head necrosis when the diagnosis Legg-Calvé-Perthes disease is made. Those who are younger than six years at the time of diagnosis or who have less than 50% femoral head necrosis should be treated symptomatically. Abduction orthosis has no place in the treatment of Legg-Calvé-Perthes disease.

How much varus is optimal with proximal femoral osteotomy to preserve the femoral head in Legg-Calvé-Perthes disease?

BACKGROUND

Although proximal femoral varus osteotomy is an established operative treatment for Legg-Calvé-Perthes disease, there is a lack of data on how much varus at the osteotomy is optimal for preserving the spherical shape of the femoral head. The purpose of this study was to determine if there is a correlation between the amount of varus used and the Stulberg radiographic outcome at maturity and to determine if the varus angulation improved over time.

METHODS

The database and the radiographs of fifty-two patients treated with proximal femoral varus osteotomy from a multicenter prospective study were analyzed. The neck-shaft angles were measured before the operation, after the operation, and at the time of final follow-up, and the amount of varus placed was correlated with the Stulberg outcome at skeletal maturity. Spearman correlations and logistic regression were used for statistical analysis.

RESULTS

All patients were six years of age or older at the time of diagnosis (mean 8.0 ± 1.4 years), and all were skeletally mature at the time of follow-up (mean age [and standard deviation] at the time of follow-up, 16.5 ± 2.0 years). The mean neck-shaft angle was 138° ± 7° preoperatively and 115° ± 11° postoperatively with a mean varus change of 23° ± 10°. No significant correlation was observed between the postoperative neck-shaft angle at maturity and the Stulberg outcome (r = -0.15, p = 0.17) and between the amount of varus placed and the Stulberg outcome (r = 0.14, p = 0.36). However, when the lateral pillar groups were analyzed separately with use of logistic regression, a significant relationship was observed for the lateral pillar group B (p = 0.025), with a higher postoperative neck-shaft angle having a greater probability of being associated with a Stulberg class-I or II outcome. At maturity, the mean neck-shaft angle had improved from 115° ± 11° following the initial surgery to 124° ± 8°. However, nineteen (37%) of the fifty-two patients showed no improvement (defined as a change of >5°) and fifteen (29%) of the fifty-two patients had an overriding greater trochanter.

CONCLUSIONS

Contrary to the conventional belief, greater varus angulation does not necessarily produce better preservation of the femoral head following proximal femoral varus osteotomy. Given the results, our recommendation is to achieve 10° to 15° of varus correction when performing proximal femoral varus osteotomy on hips that are in the early stages of Legg-Calvé-Perthes disease.

Guided growth of the proximal femur: a pilot study in the lamb model

BACKGROUND

The concept of guided growth has been used for decades in the lower extremities of children, but has not been applied to correct varus or valgus deformity in the hip, such as those that occur in children with cerebral palsy or developmental dysplasia of the hip. The purpose of this study is to determine whether guided growth techniques are effective at altering the morphology of the proximal femur in a lamb model.

METHODS

Ten, 2-month-old mixed-breed male lambs underwent hemiepiphyseal drilling and screw placement. Drilling occurred eccentrically (inferiorly) in an attempt to close only a portion of the growth plate. In 5 lambs, a sham surgery was performed in which the screw did not cross the proximal femoral physis. Growth was compared between groups and with the opposite hip in which no procedure was performed in both groups. Standardized radiographs were obtained preoperatively and monthly. A 3-dimensional computed tomography scan and standard histology were obtained postnecropsy. Version and neck shaft angle (NSA) was determined and recorded at the time of the index procedure with the aid of fluoroscopy. Radiographs were assessed by measurement of the NSA and the articular trochanteric distance (ATD). Results were compared by using the t test: paired 2 sample for means.

RESULTS

The NSA and ATD were compared preoperatively and at a mean of 3.3 months after surgery. They were no significant differences preoperatively between the screw or sham group. Postoperatively, the NSA was 132 versus 143 (P=0.006) and the ATD -0.6 mm versus 10 mm (P=0.033) for the screw and sham hips, respectively. The sham group showed no statistical differences between the operative and nonoperative sides postoperatively, although the ATD trended toward a larger number on the "sham" side, possibly because of a growth stimulation effect.

CONCLUSIONS

Screw hemiepiphysiodesis seems to alter the growth of the proximal femur in the lamb model.

SIGNIFICANCE

Further studies are ongoing and with more research this technique could be used to correct or prevent proximal femoral deformity in the growing child.

LEVEL OF EVIDENCE

Level II.

Reliability and agreement of measures used in radiographic evaluation of the adult hip

BACKGROUND

Several mechanical derangements reportedly contribute to the development of noninflammatory arthritis of the hip. Diagnosis of these derangements involves the use of specific radiographic measures (eg, alpha angle, lateral center edge angle, cross-over sign). The reliability of some of these measures is not known, whereas others have not been confirmed.

QUESTIONS/PURPOSES

We examined the reproducibility of 20 radiographic parameters of the hip used in clinical practice.

METHODS

Twenty radiographic parameters on standardized digital AP and cross-table lateral radiographs were evaluated by two observers on two different occasions. The parameters were evaluated from the standpoint of reproducibility (reliability and agreement). The intraclass correlation coefficient (ICC), kappa coefficient, and standard error of measurement were calculated. The minimal detectable change was calculated where possible.

RESULTS

Interrater reliability ranged from 0.45 to 0.90 for ICC depending on the measure. Intrarater reliability ranged from 0.55 to 0.99. Measurements that could be measured directly (femoral head diameter) were more reliable than measurements requiring estimation on the part of the observer (Tönnis angle, neck-shaft angle). Categorical parameters had interrater and intrarater reliability kappa values greater than 0.90 for all parameters measured. Agreement between repeated measurements, as given by the minimal detectable change, showed many parameters with low absolute reliability have clinical use in the context of the large changes seen in clinical practice.

CONCLUSION

Radiographic hip measures show clinical utility when evaluated from the perspective of agreement and reliability.

CLINICAL RELEVANCE

All measures investigated show clinical utility when evaluated from the perspective of reliability and agreement.

LEVEL OF EVIDENCE

Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Intra- and interobserver reliability analysis of digital radiographic measurements for pediatric orthopedic parameters using a novel PACS integrated computer software program

BACKGROUND

The between-observer reliability of repeated anatomic assessments in pediatric orthopedics relies on the precise definition of bony landmarks for measuring angles, indexes, and lengths of joints, limbs, and spine. We have analyzed intra- and interobserver reliability with a new digital measurement system (TraumaCad Wizard™).

METHODS

Five pediatric orthopedic surgeons measured 50 digital radiographs on three separate days using the TraumaCad system. There were 10 anterior-posterior (AP) pelvic views from developmental dysplasia of the hip (DDH) patients, 10 AP pelvic views from cerebral palsy (CP) patients, 10 AP standing view of the lower limb radiographs from leg length discrepancy (LLD) patients, and 10 AP and 10 lateral spine X-rays from scoliosis patients. All standing view of the lower limb radiographs were calibrated by the software to allow for accurate length measurements, using as reference a 1-inch metal ball placed at the level of the bone. Each observer performed 540 measurements (totaling 2,700). We estimated intra- and interobserver standard deviations for measurements in all categories by specialists and nonspecialists. The intraclass correlation coefficient (ICC) summarized the overall accuracy and precision of the measurement process relative to subject variation. We examined whether the relative accuracy of a measurement is adversely affected by the number of bony landmarks required for making the measurement.

RESULTS

The overall ICC was >0.74 for 13 out of 18 measurements. Accuracy of the acetabular index for DDH was greater than for CP and relatively low for the center-edge angle in CP. Accuracy for bone length was better than for joint angulations in LLD and for the Cobb angle in AP views compared to lateral views for scoliosis. There were no clinically important biases, and most of the differences between specialists and nonspecialists were nonsignificant. The correlation between the results according to the number of bony landmarks that needed to be identified was also nonsignificant.

CONCLUSIONS

Digital measurements with the TraumaCad system are reliable in terms of intra- and interobserver variability, making it a useful method for the analysis of pathology on radiographs in pediatric orthopedics.

Triple pelvic osteotomy in the treatment of hip dysplasia

INTRODUCTION

Insufficient femoral head coverage is found in a variety of diseases, with acetabular dysplasia as the most frequent disorder and triple pelvic osteotomy as the most recently introduced surgical treatment.

OBJECTIVE

This study analyses pre- and postoperative pathoanatomic characteristics of triple in comparison to Salter and Chiari osteotomies, with a logistic regression analysis of outcome predictor and effect explanator factors in relation to the chosen type of operation.

METHODS

The study involved 136 adolescents treated with Salter and Chiari osteotomies or a triple pelvic osteotomy at the Institute of Orthopaedic Surgery "Banjica" in Belgrade. The patients were between 10-20 years old at the time of operation. We collected and analyzed data from all the patients: illness history, operative parameters, preoperative and postoperative pathoanatomic data. The data was statistically processed using the statistical software SPSS, defining standard descriptive values, and by using the appropriate tests of analytic statistics: t-test for dependent and independent variables, chi2-test, Fisher's exact test, Wilcoxon's test, parameter correlation, one-way ANOVA, multi-factorial ANOVA and logistic regression, according to the type of the analyzed data and the conditions under which the statistical methods were applied.

RESULTS

The average CE angle after triple pelvic osteotomy was 43.5 degrees, more improved than after the Salter osteotomy (33.0 degrees) and Chiari osteotomy (31.4 degrees) (F = 16.822; p < 0.01). Postoperative spherical congruence was also more frequent after the triple osteotomy than after the other two types of operations, and with a high significance. Preoperative painful discomfort was found to be a valid predictor of indications for the triple osteotomy over both Chiari and Salter osteotomies. The valid explanators of effect for the triple osteotomy are: postoperative joint congruence (compared to the Chiari osteotomy) and increase in joint coverage (compared to Salter osteotomy).

CONCLUSION

Triple pelvic osteotomy is the method of choice in the management of acetabular dysplasia and other disturbances of hip joint containment in adolescent age.

Changes in the lateral pillar classification in Perthes' disease

The purpose of this study was to examine the correlation between the changes in the lateral pillar grades and the factors influencing such changes. We reviewed 102 patients with Perthes' disease. Changes were observed in 32 (31%) hips. The percentage of the changes in each treatment group showed significant differences. Patients with extensive involvement showed significantly more changes. There was no difference in the age at the onset. We recommend that treatment methods be used that more effectively relieve the mechanical force on the capital femoral epiphysis for patients with extensive involvement regardless of the age at the onset.

Prognostic factors and outcome of treatment in Perthes' disease: a prospective study of 368 patients with five-year follow-up

This nationwide prospective study was designed to determine prognostic factors and evaluate the outcome of different treatments of Perthes' disease. A total of 28 hospitals in Norway were instructed to report all new cases of Perthes' disease over a period of five years and 425 patients were reported and followed for five years. Of these, 368 with unilateral disease were included in the present study. The hips were classified radiologically according to a modified two-group Catterall classification and the lateral pillar classification. A total of 358 patients (97%) attended the five-year follow-up, when a modified three-group Stulberg classification was used as a radiological outcome measure. For patients over six years of age at diagnosis and with more than 50% necrosis of the femoral head (152 patients), the surgeons at the different hospitals had chosen one of three methods of treatment: physiotherapy (55 patients), the Scottish Rite abduction orthosis (26), and proximal femoral varus osteotomy (71). Of these hips, 146 (96%) were available for the five-year follow-up. The strongest predictor of outcome was femoral head involvement of more or less than 50% (odds ratio (OR) = 7.76, 95% confidence interval (CI) 2.82 to 21.37), followed by age at diagnosis (OR = 0.98, 95% CI 0.92 to 0.99) and the lateral pillar classification (OR = 0.62, 95% CI 0.40 to 0.98). In children over six years at diagnosis with more than 50% of femoral head necrosis, proximal femoral varus osteotomy gave a significantly better outcome than orthosis (p = 0.001) or physiotherapy (p = 0.001). There was no significant difference between the physiotherapy and orthosis groups (p = 0.36), and we found no difference in outcome after any of the treatments in children under six years (p = 0.73). We recommend proximal femoral varus osteotomy in children aged six years and over at the time of diagnosis with hips having more than 50% femoral head necrosis. The abduction orthosis should be abandoned in Perthes' disease.

Reliability of radiological classifications used in Legg-Calve-Perthes disease

Radiological assessment is a valuable tool in the assessment, management and prognostication of Perthes disease. Radiological assessment, however, is not an easy task and all classification systems used in Perthes disease have some degree of interrater and intrarater variabilities. In the past, there were some isolated studies to find the reliability of the classifications used in Perthes disease. In this study, we comprehensively studied three most commonly used radiological classifications (Salter-Thompson, lateral pillar and Catterall). We had 44 patients' radiographs (anteroposterior and lateral) taken in the fragmentation stage, and two experienced observers assessed and classified the radiographs on two separate occasions. In this study, we found that the average interrater reliability of the Salter-Thompson, lateral pillar and Catterall classifications was 0.163 (0.08-0.236), 0.722 (0.581-0.824) and 0.433 (0.280-0.546), respectively. The intrarater reliability was 0.313 and 0.699 for the Salter-Thompson, 0.707 and 0.658 for the lateral pillar and 0.38 and 0.577 for the Catterall classifications. Further, we tried to determine the possible reason for the low reliability associated with the Catterall classification. We think that the quantitative method of lateral pillar has better intrarater and interrater reliabilities than other classification systems, and the reliability of the Catterall classification can be significantly improved if some radiological parameters such as metaphyseal reaction and identification of the junction of involved to uninvolved region can be optimized.

Development of the hip joints in unoperated children with cerebral palsy: a radiographic study of 76 patients

BACKGROUND

The aims of the present study were to assess the development of hip dysplasia in children with bilateral spastic cerebral palsy and to evaluate the factors that influence the progression.

PATIENTS AND METHODS

76 children, 42 with spastic quadriplegia and 34 with diplegia, were included in the study. Their mean age at the first radiographic examination was 3.5 (1-11) years. The patients were followed up until operative treatment (54 subjects) or until the most recent radiograph in those who did not undergo hip surgery. The mean length of follow-up was 4.8 (1-13) years. On the initial and most recent radiographs, the migration percentage (MP) was measured, which is the percentage of the femoral head lateral to the acetabular rim.

RESULTS

The mean MP of the side with the largest displacement was 25% (-18-66) at the initial radiographic examination and 51% (9-100) at the last follow-up. The mean increase in MP was 7% (-2-33) per year. Linear multiple regression revealed that gait function and age were the most important variables that influenced the rate of MP progression. Children who could not walk had significantly greater MP progression per year (12%) than those who walked with or without support (2%). In the quadriplegics, the maximal yearly increase in MP was 13% under 5 years of age and 7% in older children. This difference was statistically significant, whereas no significant difference in relation to patient age was seen in the diplegics.

INTERPRETATION

There is a pronounced trend towards displacement of the hips in quadriplegic CP patients who are under 5 years of age and cannot walk. Because hip dislocation may lead to severe problems, close follow-up is important in finding the appropriate time for hip surgery in order to avoid progression towards dislocation. The risk of severe hip dysplasia is considerably less in spastic diplegia.

The accuracy and reliability of estimation of lateral pillar height in determining the herring grade in Legg-Calvé-Perthes disease

The amount of the preserved lateral pillar height (LPH) for assigning Herring grades is estimated during daily practice in Perthes disease. Despite this estimation, Herring classification has been reported to have a good interobserver agreement. The purpose of this study was to investigate whether the amount of preserved LPH has an effect on interobserver agreement. The results of surgeons' estimates were compared with objective measurement results. Good agreement was found among three experienced pediatric orthopaedic surgeons in 50 patients (1 vs. 2, kappa=0.527; 2 vs. 3, kappa=0.526; 1 vs. 3, kappa=0.539). Twenty of these cases had a ratio of the LPH scattered between 0.45 and 0.60 and 0.90 and 0.99 (transition between group B and C, and group A and B). When the borderline cases were evaluated separately, the interobserver reliability was poor (1 vs. 2, kappa=0.194; 2 vs. 3, kappa=0.256; 1 vs. 3, kappa=0.154), which may be explained by misperception of the preserved LPH. If the Herring classification is to be used as the prognostic indicator for deciding among the treatment alternatives, and LPH is the major determinant of the management, measurements should be used instead of estimates, especially in borderline cases.

Interobserver and intraobserver reliability in the load sharing classification of the assessment of thoracolumbar burst fractures

STUDY DESIGN

The Load Sharing Classification of spinal fractures was evaluated by 5 observers on 2 occasions.

OBJECTIVE

To evaluate the interobserver and intraobserver reliability of the Load Sharing Classification of spinal fractures in the assessment of thoracolumbar burst fractures.

SUMMARY OF BACKGROUND DATA

The Load Sharing Classification of spinal fractures provides a basis for the choice of operative approaches, but the reliability of this classification system has not been established.

METHODS

The radiographic and computed tomography scan images of 45 consecutive patients with thoracolumbar burst fractures were reviewed by 5 observers on 2 different occasions 3 months apart. Interobserver reliability was assessed by comparison of the fracture classifications determined by the 5 observers. Intraobserver reliability was evaluated by comparison of the classifications determined by each observer on the first and second sessions. Ten paired interobserver and 5 intraobserver comparisons were then analyzed with use of kappa statistics.

RESULTS

All 5 observers agreed on the final classification for 58% and 73% of the fractures on the first and second assessments, respectively. The average kappa coefficient for the 10 paired comparisons among the 5 observers was 0.79 (range 0.73-0.89) for the first assessment and 0.84 (range 0.81-0.95) for the second assessment. Interobserver agreement improved when the 3 components of the classification system were analyzed separately, reaching an almost perfect interobserver reliability with the average kappa values of 0.90 (range 0.82-0.97) for the first assessment and 0.92 (range 0.83-1) for the second assessment. The kappa values for the 5 intraobserver comparisons ranged from 0.73 to 0.87 (average 0.78), expressing at least substantial agreement; 2 observers showed almost perfect intraobserver reliability. For the 3 components of the classification system, all observers reached almost perfect intraobserver agreement with the kappa values of 0.83 to 0.97 (average, 0.89).

CONCLUSIONS

Kappa statistics showed high levels of agreement when the Load Sharing Classification was used to assess thoracolumbar burst fractures. This system can be applied with excellent reliability.

Evaluation of the subchondral fracture in predicting the extent of femoral head necrosis in Perthes disease: a prospective study of 92 patients

The aim of this study was to evaluate the subchondral fracture as a predictor for the extent of femoral head necrosis in Perthes disease. Out of 392 patients, 92 (23.5%) had a detectable subchondral fracture at the time of diagnosis. There was concordance between predicted Catterall groups on the basis of the extent of the subchondral fracture and the actual Catterall groups at the time of maximal resorption in 61% of the cases, when assessed by an experienced observer. When using the extent of the subchondral fracture to predict Salter-Thompson groups, this observer obtained 89% concordance with the actual Salter-Thompson groups at the time of maximal resorption. The inter-observer agreement between the experienced and a less experienced observer regarding the presence or absence of a subchondral fracture was moderate (weighted kappa 0.59, 87% agreement). When using the extent of the subchondral fracture as a measure of femoral head involvement (Catterall groups), the inter-observer agreement was moderate (weighted kappa 0.46). Patients with detectable subchondral fracture were significantly older (mean 6.5 years) at the time of diagnosis than those without visible fracture (mean 5.2 years). The delay in diagnosis was significantly shorter in the group with subchondral fracture (mean 3.2 months) than among patients without visible fracture (mean 4.9 months). There was no significant difference with regard to sex, pain level, pain localization, or limping gait between the two groups. We conclude that the subchondral fracture is a relatively rare early sign in Perthes disease. When present, it is a useful sign when assessed by an experienced observer as its extent was in fairly good concordance with the extent of femoral head involvement at the time of maximal resorption. Awareness of this radiographic sign will aid the orthopaedic surgeon to establish diagnosis and, to some degree, to predict prognosis early in the course of the disease.