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

Effectiveness of therapeutic methods for Legg-Calvé-Perthes disease according to staging, limits of conservative treatment: a systematic review with meta-analysis

Legg-Calvé-Perthes disease (LCPD) is known as a self-limiting pediatric orthopedic pathology that affects the hip due to ischemia with consequent aseptic avascular necrosis of the femoral head. This is a systematic literature review carried out in the databases indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) in accordance with the precepts established by the PRISMA methodology (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The aim was to compare the effectiveness of treatment for Legg-Calvé-Perthes disease in relation to its staging: the limits of conservative treatment. Conservative treatment was used in four studies, and most patients under the age of 6.5 had Stulberg I and II results. Older patients, between eight and ten years old, had a relatively better classification when they underwent surgical treatment. In this context, the data collected did not show significant variations; however, it was possible to observe that conservative treatment was more effective in this population, while surgical treatment is better recommended at older ages.

Predictors of Persistent Limp Following Proximal Femoral Varus Osteotomy for Perthes Disease

INTRODUCTION

One of the most popular containment procedures for Legg-Calvé-Perthes disease (LCPD) is proximal femur varus osteotomy (PFO). While generally successful in achieving containment, PFO can cause limb length discrepancy, abductor weakness, and (of most concern for families) a persistent limp. While many studies have focused on radiographic outcomes following containment surgery, none have analyzed predictors of this persistent limp. The aim of this study was to determine clinical, radiographic, and surgical risk factors for persistent limp 2 years after PFO in children with LCPD.

METHODS

A retrospective review of a prospectively collected multicenter database was conducted for patients aged 6 to 11 years at disease onset with unilateral early-stage LCPD (Waldenström I) who underwent PFO. Limp status (no, mild, and severe), age, BMI, and pain scores were obtained at initial presentation, 3-month, and 2-year postoperative visits. Preoperative and follow-up radiographs were used to measure traditional morphologic hip metrics including acetabular index (AI), lateral center-edge angle (LCEA), and femoral neck-shaft angle (NSA). Univariate analysis as well as multivariate logistic regression models were used to analyze factors associated with mild and severe limp at the 2-year visit.

RESULTS

A total of 95 patients met the inclusion criteria, and of these 50 patients underwent concomitant greater trochanter apophysiodesis (GTA) at the time of PFO. At the 2-year visit, there were 38 patients (40%) with a mild or severe limp. Multivariate logistic regression revealed no significant radiographic factors associated with a persistent limp. However, lower 2-year BMI and undergoing GTA were associated with decreased rates of persistent limp regardless of age ( P <0.05). When stratifying by age of disease onset, apophysiodesis appeared to be protective against any severity of limp in patients aged 6 to 8 years old ( P = 0.03), but not in patients 8 years or older ( P = 0.49).

CONCLUSIONS

Persistent limp following PFO is a frustrating problem that was seen in 40% of patients at 2 years. However, lower follow-up BMI and performing a greater trochanter apophysiodesis, particularly in patients younger than 8 years of age, correlated with a lower risk of postoperative limp.

Demographics and risk for containment surgery in patients with unilateral Legg-Calvé-Perthes disease: a national population-based cohort study of 309 patients from the Swedish Pediatric Orthopedic Quality Register

BACKGROUND AND PURPOSE

It is controversial as to which patients affected by Legg-Calvé-Perthes disease (LCPD) benefit from containment surgery. This population-based study based on data from a national quality registry aims to assess the incidence of LCPD and to explore which factors affect the decision for surgical intervention.

METHODS

This observational study involved 309 patients with unilateral LCPD reported between 2015 and 2023 to the Swedish Pediatric Orthopedic Quality Register (SPOQ). Descriptive statistics and logistic regression models were used for analysis.

RESULTS

In 2019, the assessed incidence of LCPD in the Swedish population of 2-12-year-olds was 4.2 per 105. 238 (77%) were boys with a mean age of 6 years. At diagnosis, 55 (30%) were overweight or obese, rising to 17 patients (39%) and 16 patients (40%) at 2-year follow-up for surgically and non-surgically treated groups, respectively. At diagnosis, affected hips had reduced abduction compared with healthy hips, and their abduction remained restricted at the 2-year follow-up. Surgically treated patients had inferior abduction compared with non-surgically treated ones at diagnosis. The adjusted risk for containment surgery increased with age and in the presence of a positive Trendelenburg sign but decreased with greater hip abduction.

CONCLUSION

We found a lower national yearly incidence (4.2 per 105) than previously reported in Swedish studies. A higher proportion of overweight or obese patients compared with the general Swedish population of 4-9-year-olds was identified. Increasing age, positive Trendelenburg sign, and limited hip abduction at diagnosis correlated with increased surgical intervention likelihood.

Fully automatic system to detect and segment the proximal femur in pelvic radiographic images for Legg-Calvé-Perthes disease

This study aimed to develop a method using computer vision techniques to accurately detect and delineate the proximal femur in radiographs of Legg-Calvé-Perthes disease (LCPD) patients. Currently, evaluating femoral head deformity, a crucial predictor of LCPD outcomes, relies on unreliable categorical and qualitative classifications. To address this limitation, we employed the pretrained object detection model YOLOv5 to detect the proximal femur on over 2000 radiographs, including images of shoulders and chests, to enhance robustness and generalizability. Subsequently, we utilized the U-Net convolutional neural network architecture for image segmentation of the proximal femur in more than 800 manually annotated images of stage IV LCPD. The results demonstrate outstanding performance, with the object detection model achieving high accuracy (mean average precision of 0.99) and the segmentation model attaining an accuracy score of 91%, dice coefficient of 0.75, and binary IoU score of 0.85 on the held-out test set. The proposed fully automatic proximal femur detection and segmentation system offers a promising approach to accurately detect and delineate the proximal femoral bone contour in radiographic images, which is essential for further image analysis in LCPD patients. Clinical significance: This study highlights the potential of computer vision techniques for enhancing the reliability of Legg-Calvé-Perthes disease staging and outcome prediction.

Epidemiology, natural evolution, pathogenesis, clinical spectrum, and management of Legg-Calvé-Perthes

Background

Legg-Calvé-Perthes disease is a self-limiting disorder that develops in children following interruption of the blood supply to the capital femoral epiphysis. This review outlines the current knowledge on the epidemiology, natural evolution, clinical spectrum, and management of the disease.

Methods

The literature pertaining to these aspects of the disease were studied and summarized in this review.

Results

Epidemiological studies suggest that environmental factors contribute to the causation of the disease. Incidence rates monitored over time indicate that the incidence of Legg-Calvé-Perthes disease is declining. The natural evolution followed on sequential plain radiographs enables division of the disease into Stages Ia, Ib, IIa, IIb, IIIa, IIIb, and IV. Reversible deformation of the capital occurs in Stages Ia-IIa simply on standing while irreversible deformation may occur in Stages IIb and IIIa. Treatment of Legg-Calvé-Perthes disease in Stages Ia-IIa aims to prevent the femoral head from getting deformed by containment and avoidance of weight-bearing. In Stages IIb and IIIa, treatment aims to remedy the effects of early irreversible deformation of the femoral head. In Stage IIIb and IV, treatment is directed to correcting the altered shape of the femoral head. The impression that these treatment methods are helpful is based on poor quality evidence.

Conclusion

There is an urgent need to undertake Level I studies to establish the efficacy of currently treatment.

Level of evidence

level V.

Prognostic value of bone resorption pattern in the anterior portion of the femoral head in Legg-Calvé-Perthes disease

Purpose

To examine whether differences in bone resorption patterns in the anterior portion of the femoral head correlate with the prognosis of Legg-Calvé-Perthes disease.

Methods

Seventy-eight patients with unilateral Legg-Calvé-Perthes disease, who were diagnosed after 6.0 years of age, underwent the Salter innominate osteotomy from 1987 to 2013, and were followed up to skeletal maturity. The anterior bone resorption pattern of the femoral head was evaluated from a frog-leg lateral hip radiograph made in the middle of the fragmentation period, and classified into two types, an epiphysis-preserved type (P) and a physis-disrupted type (D). The correlation between the type of bone resorption and the Stulberg outcome was analyzed.

Results

The Stulberg outcomes were grade I for 9 patients, grade II for 31, grade III for 35, and grade IV for 3, with a mean follow-up period of 8.3 ± 2.7 years. Fifty-one patients demonstrated the type P hips and 27 did the type D hip. In a subset analysis of patients with the modified lateral pillar group-B hips in the younger group (6.0-8.9 years of age at diagnosis), the percentages of the favorable and unfavorable outcomes significantly differed between the two types (p = 0.013). Anteroposterior enlargement of the affected femoral head was significantly greater in the type D hips than the type P hips (p = 0.014).

Conclusion

Unfavorable hip morphology at skeletal maturity can be predicted in patients with the lateral pillar group-B hips by focusing on bone resorption patterns of the anterior portion of the femoral head.

Level of evidence

Level III, prognostic study.

Does Prolonged Weight Relief Increase the Chances of a Favourable Outcome After Containment for Perthes Disease?

We have been treating children with Legg-Calvé-Perthes disease (LCPD) with a femoral varus osteotomy (PFVO) and weight relief till the disease evolves to the latter part of the stage of reconstitution (Stage IIIb). This entails weight relief for 18 to 24 months. We undertook this case-control study to test if a shorter period of weight relief would compromise the chance of retaining the spherical shape of the femoral head when the disease healed. Forty-one children diagnosed in the early stages of LCPD (Stages Ia, Ib, and IIa), were treated by PFVO and non-weight-bearing for a period of 6 months following surgery (6m group). Eighty-two children with LCPD matched for age, sex, and stage at surgery, who resumed weight-bearing only once they reached Stage IIIb, served as the control group (3b group). Both groups were followed up till the disease healed. The sphericity deviation score was calculated, and the height and width of the epiphysis were measured on the first radiograph designated as Stage IV. The median sphericity deviation score value at healing was 3 in the 3b group and 11 in the 6m group (P<0.001). The frequency of spherical heads was 76% in the 3b group and 49% in the 6m group (P<0.003). The Odds Ratio of the disease healing with an aspherical head in 6-month group was 3.05 (CI: 1.28 to 7.22) compared with the 3b group. The percentage increase in width of the femoral epiphysis at healing was greater in the 6 group (111.5±8.5% vs. 106.5±7.2%; P<0.001). The study confirms that containment by PFVO performed early in the course of LCPD combined with weight relief till the disease has evolved to Stage IIIb is likely to result in spherical hips in 75% of children. Reducing the period of weight relief to 6 months may yield significantly poorer results with only 49% spherical femoral heads.

Modified Clavien-Dindo-Sink system is reliable for classifying complications following surgical treatment of early-onset scoliosis

PURPOSE

Appropriately measuring and classifying surgical complications is a critical component of research in vulnerable populations, including children with early-onset scoliosis (EOS). The purpose of this study was to assess the inter- and intra-rater reliability of a modified Clavien-Dindo-Sink system (CDS) classification system for EOS patients among a group of pediatric spinal deformity surgeons.

METHODS

Thirty case scenarios were developed and presented to experienced surgeons in an international spine study group. For each case, surgeons were asked to select a level of severity based on the modified CDS system to assess inter-rater reliability. The survey was administered on two occasions to allow for assessment of intra-rater reliability. Weighted Kappa values were calculated, with 0.61 to 0.80 considered substantial agreement and 0.81 to 1.00 considered nearly perfect agreement.

RESULTS

11/12 (91.7%) surgeons completed the first-round survey and 8/12 (66.7%) completed the second. Inter-observer weighted kappa values for the first and second survey were 0.75 [95% CI 0.56-0.94], indicating substantial agreement, and 0.84 [95% CI 0.70-0.98], indicating nearly perfect agreement, respectively. Intra-observer reliability was 0.86 (range 0.74-0.95) between the first and second surveys, indicating nearly perfect agreement .

CONCLUSION

The modified CDS classification system demonstrated substantial to nearly perfect agreement between and within observers for the evaluation of complications following the surgical treatment of EOS patients. Adoption of this reliable classification system as a standard for reporting complications in EOS patients can be a valuable tool for future research endeavors, as we seek to ultimately improve surgical practices and patient outcomes.

LEVEL OF EVIDENCE

Level V.

RADIOGRAPHIC STUDY OF THE MEDIAL JOINT SPACE OF THE HIP IN LEGG-CALVÉ-PERTHES DISEASE

Objective

To evaluate medial joint space in affected and normal contralateral hips in patients with Legg-Calvé-Perthes disease (LCPD).

Methods

To compare joint space, femoral head extrusion (FHE), medial space coefficient (MSC) of the hip, and femoral head width (FHW) in affected and normal hips, using 127 radiographs of patients with unilateral LCPD and considering age groups under and over six years old as well as their disease stage.

Results

No statistically significant differences were observed regarding MSC between normal and affected hips regardless of disease staging. However, medial joint distance was significantly greater in affected hips than in normal hips. In the necrosis and fragmentation phase, distance from medial space in affected hips was significantly greater than in contralateral normal hips. Comparing only affected hips, MSC and FHW showed statistically significant differences and the group > 6 yo presented higher values. Among normal hips, the group < 6 yo presented a statistically significant difference considering the MSC and FHW.

Conclusions

No statistically significant difference was found between the medial joint space of affected and normal hips, except for early stages of the disease (necrosis and fragmentation). The isolated use of radiographic study is insufficient in LCPD and the lack of complementation with other exams, such as magnetic resonance, can delay diagnosis of and onset of treatment for the disease. Level of Evidence III, Study of Non Consecutive Patients; without Consistently Applied Reference "Gold" Standard.

Surgical hip dislocation with relative femoral neck lengthening and retinacular soft-tissue flap for sequela of Legg–Calve–Perthes disease

Objective

Correction of post-LCP (Legg–Calve–Perthes) morphology using surgical hip dislocation with retinacular flap and relative femoral neck lengthening for impingent correction reduces the risk of early arthritis and improves the survival of the native hip joint.

Indications

Typical post-LCP deformity with external and internal hip impingement due to aspherical enlarged femoral head and shortened femoral neck with high riding trochanter major without advanced osteoarthritis (Tönnis classification ≤ 1) in the younger patient (age < 50 years).

Contraindications

Advanced global osteoarthritis (Tönnis classification ≥ 2).

Surgical technique

By performing surgical hip dislocation, full access to the hip joint is gained which allows intra-articular corrections like cartilage and labral repair. Relative femoral neck lengthening involves osteotomy and distalization of the greater trochanter with reduction of the base of the femoral neck, while maintaining vascular perfusion of the femoral head by creation of a retinacular soft-tissue flap.

Postoperative management

Immediate postoperative mobilization on a passive motion device to prevent capsular adhesions. Patients mobilized with partial weight bearing of 15 kg with the use of crutches for at least 8 weeks.

Results

In all, 81 hips with symptomatic deformity of the femoral head after healed LCP disease were treated with surgical hip dislocation and offset correction between 1997 and 2020. The mean age at operation was 23 years; mean follow-up was 9 years; 11 hips were converted to total hip arthroplasty and 1 patient died 1 year after the operation. The other 67 hips showed no or minor progression of arthrosis. Complications were 2 subluxations due to instability and 1 pseudarthrosis of the lesser trochanter; no hip developed avascular necrosis.

The "Discoid Epiphysis"-An Uncommon Presentation of Legg-Calvé-Perthes Disease

BACKGROUND

Among a cohort of 402 children with Legg-Calvé-Perthes disease (LCPD), 32 children presented with sclerosis and severe collapse of the entire femoral epiphysis that closely resembled a discus.This study was undertaken to identify the characteristics of children with this form of a "discoid epiphysis," compare them with typical LCPD and ascertain the radiologic outcome of their hips when the disease healed.

METHODS

Sequential radiographs of the children were studied to monitor disease evolution. Femoral epiphyseal extrusion was measured on the initial anteroposterior radiograph. Thirty-one of the 32 children were treated with a proximal femoral varus osteotomy and weight-bearing was deferred till the disease reached stage IIIb. The pattern of fragmentation of the epiphysis was noted and the Sphericity Deviation Score (SDS) was computed once the disease healed.

RESULTS

The mean age of children with a discoid epiphysis was 6.81±1.57 years at onset of symptoms while that of children with the typical presentation was 7.54±1.64 years (P<0.017). Perfusion magnetic resonance imaging scans of three children with a discoid epiphysis done in stage Ib of the disease showed that over 95% of the epiphysis was avascular. Femoral head extrusion was frequently present on the initial radiographs (mean Reimer's migration index 27.08±8.7; range: 6.4 to 42.55).In operated children with a discoid epiphysis, the disease evolved typically with fragmentation of the epiphysis followed by reconstitution. The height of the epiphysis was never restored; when the disease healed the mean epiphyseal height was 51.31±10.44% of the normal contralateral epiphysis as compared with 82.46±11.24% in children with typical LCPD (P<0.001).The SDS at healing of operated children with a discoid epiphysis was 14.95±10.86 while the SDS for operated children without a discoid epiphysis was 9.77±11.7 (P<0.019). However, the SDS of children with typical onset LCPD who had Catterall IV involvement and Herring C collapse was 15.25±15.19 (P=0.49 NS).

CONCLUSION

The outcome of treatment of children with a discoid epiphysis is comparable to that of children with typical onset LCPD with Catterall IV (whole-head involvement) and Herring C collapse of the lateral pillar. About a third of these children who undergo early surgical containment may have spherical heads when the disease heals.

Bypass of Epiphyseal Fragmentation Following Early Salter Innominate Osteotomy and Its Clinical Relevance in Legg-Calvé-Perthes Disease

BACKGROUND

It has been demonstrated that early femoral varus osteotomy (FVO) produces a greater probability of skipping or interruption of epiphyseal fragmentation, thereby shortening the length of fragmentation stage for hips in the active stage of Legg-Calvé-Perthes disease. This "bypassing phenomenon" is thought to effect less disease severity or outcome, whereas it remains to be elucidated whether this phenomenon is specific to early FVO. We sought to investigate the presence and characteristics of the "bypassing phenomenon" following pelvic osteotomy performed in the avascular necrosis or early fragmentation stage as well as its correlation with disease severity and radiographic outcomes.

METHODS

A retrospective review of data was conducted for 79 patients with unilateral Legg-Calvé-Perthes disease who had been diagnosed from 1987 to 2015, undergone the Salter innominate osteotomy (SIO) during the stage of avascular necrosis or in the early part of the fragmentation stage between 6.0 and 12.0 years of age, and followed up until skeletal maturity. Epiphyseal fragmentation was classified into 4 patterns according to a previous study. We compared lateral pillar groups and Stulberg grades between patients with and without bypass of the fragmentation stage.

RESULTS

The mean age at surgery and follow-up period was 8.1 and 7.9 years, respectively. Sixty hips were in the Waldenström stage I and 19 hips in stage IIa at the surgery. In hips receiving SIO during stage I, the mean duration of the fragmentation stage was 276 days. The fragmentation pattern was typical for 40 hips, abortive for 17 hips, and atypical with horizontal fissure for 3 hips. Patients whose fragmentation was aborted experienced significantly less severe lateral pillar involvement and more favorable Stulberg outcomes at skeletal maturity.

CONCLUSIONS

Incomplete bypass of epiphyseal fragmentation was observed in 28% of patients following early SIO performed in the avascular necrosis stage. In contrast to FVO, no patient bypassed fragmentation completely. Patients with incomplete bypass had a significantly higher proportion of less severe hips and a significantly greater probability of being associated with favorable radiographic outcomes compared with those without bypass.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

The British Orthopaedic Surgery Surveillance study: Perthes' disease: the epidemiology and two-year outcomes from a prospective cohort in Great Britain

Aims

The aim of this study was to evaluate the epidemiology and treatment of Perthes’ disease of the hip.

Methods

This was an anonymized comprehensive cohort study of Perthes’ disease, with a nested consented cohort. A total of 143 of 144 hospitals treating children’s hip disease in the UK participated over an 18-month period. Cases were cross-checked using a secondary independent reporting network of trainee surgeons to minimize those missing. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants.

Results

Overall, 371 children (396 hips) were newly affected by Perthes’ disease arising from 63 hospitals, with a median of two patients (interquartile range 1.0 to 5.5) per hospital. The annual incidence was 2.48 patients (95% confidence interval (CI) 2.20 to 2.76) per 100,000 zero- to 14-year-olds. Of these, 117 hips (36.4%) were treated surgically. There was considerable variation in the treatment strategy, and an optimized decision tree identified joint stiffness and age above eight years as the key determinants for containment surgery. A total of 348 hips (88.5%) had outcomes to two years, of which 227 were in the late reossification stage for which a hip shape outcome (Stulberg grade) was assigned. The independent predictors of a poorer radiological outcome were female sex (odds ratio (OR) 2.27 (95% CI 1.19 to 4.35)), age above six years (OR 2.62 (95% CI (1.30 to 5.28)), and over 50% radiological collapse at inclusion (OR 2.19 (95% CI 0.99 to 4.83)). Surgery had no effect on radiological outcomes (OR 1.03 (95% CI 0.55 to 1.96)). PROMs indicated the marked effect of the disease on the child, which persisted at two years.

Conclusion

Despite the frequency of containment surgery, we found no evidence of improved outcomes. There appears to be a sufficient case volume and community equipoise among surgeons to embark on a randomized clinical trial to definitively investigate the effectiveness of containment surgery.

Cite this article: Bone Joint J 2022;104-B(4):510–518.

The Role of the Artery of Ligamentum Teres in Revascularization in Legg-Calve-Perthes Disease

INTRODUCTION

A recent cadaveric study supported that most immature hips are supplied by the artery of ligamentum teres and suggested this medial vascular source may influence the pattern of revascularization in Legg-Calve-Perthes disease (LCPD). The purposes of this study were to characterize the perfusion pattern of the capital femoral epiphysis and determine the role of the artery of ligamentum teres in early revascularization of LCPD.

METHODS

Retrospective review of perfusion magnetic resonance imaging (pMRI) from 64 hips in early stage LCPD (Waldenström stage I to IIa) was performed. Two independent graders categorized perfusion pattern based on the presence of perfusion medially (from artery of ligamentum teres) and/or laterally (from the medial femoral circumflex artery) on coronal and sagittal MRI series: type 1-lateral perfusion only, type 2-separate medial and lateral perfusion, or type 3-coalescent medial and lateral perfusion. Lateral pillar classification was obtained for hips that reached mid-fragmentation.

RESULTS

We identified 64 patients (75% male) with mean age at diagnosis of 8.5±2.1 years. 36% (23/64) hips underwent pMRI during stage I and 64% (41/64) during stage IIa. pMRI revealed separate and distinct medial and lateral sources of perfusion (type 2) in 50% (32/64) hips. In stage I, the distribution of type 1/2/3 hips was found to be 26%/52%/22%. However, in stage IIa there was a nonsignificant trend toward greater coalescence of the medial and lateral perfusion with a distribution of type 1/2/3 of 7%/49%/44% (P=0.07). There was a nonsignificant trend toward weak negative linear correlation between lower initial perfusion grade and worsened lateral pillar classification at mid-fragmentation (r=-0.25, P=0.05).

CONCLUSION

The presence of separate and distinct areas of perfusion of medial and lateral capital femoral epiphysis provides further evidence of the role of the ligamentum teres vessels in revascularization during the early stages of LCPD. The changes in perfusion pattern with disease progression likely reflect that medial femoral circumflex artery and ligamentum teres vessel revascularization occur separately, but ultimately coalesce posteriorly over time.

LEVEL OF EVIDENCE

Level II-prognostic study.

Legg-Calvé-Perthes disease overview

Background

Legg–Calvé–Perthes Disease (LCPD) is a necrosis of the femoral head which affects the range of motion of the hips. Its incidence is variable, ranging from 0.4/100,000 to 29.0/ 100,000 children. Although LCPD was first described in the beginning of the past century, limited is known about its etiology. Our objective is to describe the main areas of interest in Legg–Calve–Perthes disease.

Methods

A review of the literature regarding LCPD etiology was performed, considering the following inclusion criteria: Studies reporting clinical or preclinical results. The research group carried out a filtered search on the PubMed and Science Direct databases. To maximize the suitability of the search results, we combined the terms ‘‘Perthes disease” OR “LCPD” OR “children avascular femoral head necrosis” with “diagnostic” OR “treatment” OR “etiology” as either key words or MeSH terms.

Results

In this article been described some areas of interest in LCPD, we include topics such as: history, incidence, pathogenesis, diagnosis, treatment and possible etiology, since LCPD has an unknown etiology.

Conclusions

This review suggests that LCPD has a multifactorial etiology where environmental, metabolic and genetic agents could be involved.

Radiologic Outcomes of Bilateral and Unilateral Perthes Disease: A Comparative Cohort Study

INTRODUCTION

This study was undertaken to compare the radiologic outcomes of bilateral and unilateral Perthes disease and also to evaluate the outcome of synchronous and metachronous bilateral Perthes disease.

METHODS

Of 353 children with Perthes disease followed up from presentation to healing during the last 10 years, 37 had bilateral involvement (11 synchronous and 26 metachronous onset). The radiologic outcomes of each hip of children with bilateral disease were compared with outcomes of 148 children with unilateral disease who were matched for age, sex, and treatment. Children with unilateral or bilateral diseases were treated with a proximal femoral varus derotation osteotomy if they fulfilled the criteria for surgery. The primary outcome measure was the shape of the femoral head at healing assessed by the Sphericity Deviation Score (SDS).

RESULTS

The children with bilateral disease were younger than those with unilateral disease (6.2 vs. 7.03 y; P<0.001), and they had a longer duration of the disease. All other characteristics of bilateral and unilateral cases were similar. The SDS values of unilateral and bilateral disease were comparable, as were the SDS of synchronous and metachronous bilateral disease. The effect of early surgery on the evolution of the disease in bilateral cases was similar to that reported in unilateral disease. The age of onset of the disease alone influenced the SDS in bilateral cases.

CONCLUSION

The age at onset of the bilateral disease is lower, the duration of the disease longer than that of unilateral disease, but the disease outcome is similar.

The Natural History of Non-operatively Managed Legg-Calvé-Perthes' Disease

BACKGROUND

The purpose of this study was to examine the evolution of Legg-Calvé-Perthes' disease (LCPD) among children from British Columbia (BC), Canada who were treated non-operatively and to compare the results to a previously conducted study in India.

METHODS

This was a retrospective review of patients treated non-operatively for LCPD in BC between 1990 and 2006 compared with a cohort from India. Demographic and treatment information were collected from medical records. Radiographs were assigned modified Waldenstrom, Catterall, Salter-Thompson and Herring classifications and intra- and interobserver reliability were assessed. We evaluated epiphyseal extrusion (EE) and metaphyseal width (MW), and assessed radiographs using the Mose and modified Stulberg classifications.

RESULTS

102 hips (90 patients) had radiographs available for evaluation. 95% of the BC cohort presented as Waldenstrom stages I and II, whereas, 90% of the Indian cohort presented as IIIa. Final EE was similar for both groups (BC 26.8%, India 27.3%) and final MW was 119% in both groups. Modified Waldenstrom and Herring classifications had substantial intra- and interobserver reliability, while Salter-Thompson and Catterall classifications had moderate agreement at best. Most hips were Catterall IV (80%) and Herring C (89%) for the BC cohort compared to only 44% and 43% of Indian hips, respectively. Most hips were irregular according to the Mose classification (BC 43%, India 52%) and aspherical according to the Stulberg classification (BC 78%).

CONCLUSIONS

We found similar radiographic progression and final radiographic appearances of LCPD in India and BC though differences in the distribution of the classification systems warrant further study.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-021-00543-x.

Asymmetrically increased femoral version with high prevalence of moderate and severe femoral anteversion in unilateral Legg-Calvé-Perthes disease

PURPOSE

To determine and stratify femoral version in Legg-Calvé-Perthes disease (LCPD), and to compare the femoral version between the LCPD hip and the contralateral unaffected hip.

METHODS

We performed a retrospective review of 45 patients with unilateral LCPD who had available CT scan through the hips and knees between January 2000 and June 2017. There were 34 (76%) male cases with a mean age of 14 years (sd 4.69). Two independent readers measured femoral version on the affected and the unaffected contralateral femur. Femoral version was classified as follows: severely decreased version (< 10°); moderately decreased (10° to 14°); normal femoral version range (15° to 20°); moderately increased (21° to 25°); and severely increased version (> 25°).

RESULTS

LCPD hips had predominantly increased femoral version (38% severely increased anteversion, 24% moderately increased anteversion), while 51% of the contralateral unaffected hips had normal femoral version (p < 0.001). LCPD hips had higher mean femoral version than the contralateral, unaffected side (mean difference = 13o; 95% confidence iterval 10o to 16o; p < 0.001). As the version of the affected hip increased, so did the discrepancy between sides. No effect of sex on the LCPD femoral version was detected (p = 0.34).

CONCLUSION

This study included a selected group of patients with unilateral LCPD and available CT scans obtained for surgical planning. The femoral version was asymmetric, with a high proportion of excessive anteversion observed at later stages of disease in the affected hips. Future studies will be necessary to determine the pathogenesis of increased femoral version associated with LCPD.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Ellipsoidal process of the femoral head in Legg-Calvé-Perthes disease. Part I

Legg-Calvé-Perthes disease (LCPD) often produces a residual deformity, typically consistent with coxa magna, coxa plana, and ellipsoidal shape. Depending on the degree of asphericity and flatness, this morphology was classified by Stulberg in stages III and IV. Thus far, few studies have investigated physeal injury as an etiological cause or evaluated its progressive profile throughout Waldenström's reossification stage and the remodelling stage. In this study, we analysed the ellipsoidal process of the femoral head. This was a retrospective control case study involving 83 unoperated hips with LCPD and Stulberg stages III and IV outcome. The data were compared with those obtained for 49 healthy contralateral hips (control). The Ellipsoidal Index, the presence of a double epiphyseal reossification nucleus, physeal narrowing, intraphyseal angle, epiphyseal height, diameter of the head, and Reimer's Index were determined. Measurements were performed at four-time points: the year the reossification stage was initiated, the final growth stage, and two equally spaced time points in between. The Ellipsoidal Index gradually increased throughout the course of the disease from 1.6 in the initial reossification stage to 2.0 at the end of growth. In the control cases, this value was consistently 1.4. More ellipsoidal deformity was observed in Stulberg stage IV versus Stulberg stage III patients (P < 0.05). Moreover, there was a direct link between a high Ellipsoidal Index and the appearance of a double reossification nucleus, a physeal narrowing in the area underlying the anterosuperior nucleus, intraphyseal angle. Reimer's Index showed a gradual extrusion from baseline to the end of growth (26.1 versus 31.8, respectively; P < 0.05). The ellipsoidal process of the femoral head occurs gradually throughout the reossification and remodelling stages. This was linked to the appearance of a double epiphyseal nucleus, gradual extrusion, an angulated physis appearance, an asymmetrical narrowing of the physis and a high Ellipsoidal Index, which may be indicative of poor prognosis. Levels of Evidence for Primary Research Question: Level III, case-control study.

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.

Identifying the Potential Differentially Expressed miRNAs and mRNAs in Osteonecrosis of the Femoral Head Based on Integrated Analysis

Purpose

Osteonecrosis of the femoral head is a common disease of the hip that leads to severe pain or joint disability. We aimed to identify potential differentially expressed miRNAs and mRNAs in osteonecrosis of the femoral head.

Methods

The data of miRNA and mRNA were firstly downloaded from the database. Secondly, the regulatory network of miRNAs-mRNAs was constructed, followed by function annotation of mRNAs. Thirdly, an in vitro experiment was applied to validate the expression of miRNAs and targeted mRNAs. Finally, GSE123568 dataset was used for electronic validation and diagnostic analysis of targeted mRNAs.

Results

Several regulatory interaction pairs between miRNA and mRNAs were identified, such as hsa-miR-378c-WNT3A/DACT1/CSF1, hsa-let-7a-5p-RCAN2/IL9R, hsa-miR-28-5p-RELA, hsa-miR-3200-5p-RELN, and hsa-miR-532-5p-CLDN18/CLDN10. Interestingly, CLDN10, CLDN18, CSF1, DACT1, IL9R, RCAN2, RELN, and WNT3A had the diagnostic value for osteonecrosis of the femoral head. Wnt signaling pathway (involved WNT3A), chemokine signaling pathway (involved RELA), focal adhesion and ECM-receptor interaction (involved RELN), cell adhesion molecules (CAMs) (involved CLDN18 and CLDN10), cytokine-cytokine receptor interaction, and hematopoietic cell lineage (involved CSF1 and IL9R) were identified.

Conclusion

The identified differentially expressed miRNAs and mRNAs may be involved in the pathology of osteonecrosis of the femoral head.

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.

Dynamic deformation of the femoral head occurs on weightbearing in Legg-Calves-Perthes disease: a translational pilot study

Aims

Though the pathogenesis of Legg-Calve-Perthes disease (LCPD) is unknown, repetitive microtrauma resulting in deformity has been postulated. The purpose of this study is to trial a novel upright MRI scanner, to determine whether any deformation occurs in femoral heads affected by LCPD with weightbearing.

Methods

Children affected by LCPD were recruited for analysis. Children received both standing weightbearing and supine scans in the MROpen upright MRI scanner, for coronal T1 GFE sequences, both hips in field of view. Parameters of femoral head height, width, and lateral extrusion of affected and unaffected hips were assessed by two independent raters, repeated at a one month interval. Inter- and intraclass correlation coefficients were determined. Standing and supine measurements were compared for each femoral head.

Results

Following rigorous protocol development in healthy age-matched volunteers, successful scanning was performed in 11 LCPD-affected hips in nine children, with seven unaffected hips therefore available for comparison. Five hips were in early stage (1 and 2) and six were in late stage (3 and 4). The mean age was 5.3 years. All hips in early-stage LCPD demonstrated dynamic deformity on weightbearing. Femoral head height decreased (mean 1.2 mm, 12.4% decrease), width increased (mean 2.5 mm, 7.2% increase), and lateral extrusion increased (median 2.5 mm, 23% increase) on standing weightbearing MRI compared to supine scans. Negligible deformation was observed in contra-lateral unaffected hips, with less deformation observed in late-stage hips. Inter- and intraclass reliability for all measured parameters was good to excellent.

Conclusion

This pilot study has described an effective novel research investigation for children with LCPD. Femoral heads in early-stage LCPD demonstrated dynamic deformity on weightbearing not previously seen, while unaffected hips did not. Expansion of this protocol will allow further translational study into the effects of loading hips with LCPD.

Cite this article: Bone Joint Open 2020;1-7:364–369.

Range of abduction in patients with Legg-Calvé-Perthes disease - a nationwide register-based cohort study

BACKGROUND

Range of abduction often decreases during Legg-Calvé-Perthes Disease (LCPD) disease. However, a good range of abduction is required during the course of LCPD, especially when containment surgery should be performed. This study aimed to investigate how many patients registered in the Swedish Pediatric Orthopedic Quality register (SPOQ) with LCPD had reduced range of abduction at diagnosis in relation to sex or age at diagnosis or severity of disease (lateral pillar class at the time at diagnosis), if physiotherapy (PT) was prescribed and has a beneficial impact in maintaining (or increasing) abduction and if the range of abduction at diagnosis before fragmentation stage is predictive for the lateral pillar classification at fragmentation stage.

METHODS

The national Swedish Pediatric Orthopedic Quality Register (SPOQ), established in 2015, is used to identify patients with LCPD. The patients are registered at three time points: at diagnosis, at potential surgery and 2 years after diagnosis. Range of abduction and information on PT are required to register at all registration sessions. One hundred ninety-nine hips from 192 children were registered in the SPOQ.

RESULTS

Of all hips, the mean range of abduction at diagnosis was 39 degrees (range 0 to 90). One hundred twenty-six patients (63%) either received instructions for PT or were referred to a physiotherapist; two patients were treated additionally with an abduction brace. There was a trend that patients who received PT, compared to patients without PT, either maintained or increased their range of abduction at the 2-year follow-up. Older age at diagnosis correlated with decreased range of abduction at the 2-year follow-up (Estimate [Est]: - 3.1, 95% confidence interval [CI]: - 4.4 to - 1.7). The degree of abduction at diagnosis before fragmentation stage correlated with the lateral pillar group at the fragmentation stage (Est: -5.3, 95% CI: - 10.0 to - 1.1).

CONCLUSION

In all, 63% of the children with LCPD in SPOQ received either written instructions or were referred to PT or both. PT seems to have a favorable impact for maintaining the range of abduction in children with LCPD. Children with a lower range of abduction at diagnosis (before the fragmentation stage) developed a higher degree of lateral pillar involvement as measured by the lateral pillar classification.

Validation of Pediatric Self-Report Patient-Reported Outcomes Measurement Information System (PROMIS) Measures in Different Stages of Legg-Calvé-Perthes Disease

OBJECTIVES

Patient-reported outcomes (PRO) assessing health-related quality of life (HRQoL) are important outcome measures, especially in Legg-Calvé-Perthes disease (LCPD) where symptoms (pain and limping), activity restrictions, and treatments vary depending on the stage of the disease. The purpose of this study was to investigate the validity of the Patient-reported Outcomes Measurement Information System (PROMIS) for measuring HRQoL of patients with LCPD in various stages of the disease.

METHODS

This is a multicenter validity study. Patients with LCPD between 4 and 18 years old were included and classified into modified Waldenström stages of disease: Early (1 or 2A), Late (2B or 3), or Healed (4). Seven PROMIS domains were collected, including Pain Interference, Fatigue, Mobility, Depression, Anger, Anxiety, and Peer Relationships. Convergent, discriminant, and known group validity was determined.

RESULTS

A total of 190 patients were included (mean age: 10.4±3.1 y). All 7 domains showed the worst scores in patients in the Early stage (known group validity). Within each domain, all domains positively correlated to each other (convergent validity). Patients who reported more anxiety, depression, and anger were associated with decreased mobility and increased fatigue and pain. Peer relationships had no to weak associations with other domains (discriminant validity).

CONCLUSIONS

PROMIS has construct validity in measuring the HRQoL of patients in different stages of LCPD, suggesting that PROMIS has potential to serve as a patient-reported outcome tool for this population.

LEVEL OF EVIDENCE

Diagnostic level III study.

Evolution of Legg-Calvé-Perthes disease following proximal femoral varus osteotomy performed in the avascular necrosis stage:a prospective study

PURPOSE

This prospective study was undertaken to describe patterns of fragmentation of the femoral epiphysis following a proximal femoral varus osteotomy (PFVO) done during stage I of LCPD and to assess the disease duration and outcome in each pattern.

METHODS

A total of 25 children treated by a PFVO in stage I of LCPD were followed until healing. The MRI Perfusion Index, radiographic changes in the femoral epiphysis, disease duration and the Sphericity Deviation Score (SDS) at healing were documented. The reproducibility of classification of the pattern of fragmentation, estimation of disease duration and SDS were assessed. The duration of the disease and SDS in the patterns of fragmentation were compared.

RESULTS

Four patterns of fragmentation were noted, namely, typical fragmentation, bypassing fragmentation, abortive fragmentation and atypical fragmentation with horizontal fissuring. The reproducibility of classifying the pattern of fragmentation was moderate (Kappa: 0.48) while the reproducibility of other continuous variables was excellent. The Perfusion Index was less than 50% in every affected hip. The duration of the disease and SDS were lowest in children in whom the stage of fragmentation was bypassed but these differences were not statistically significant.

CONCLUSION

Following a proximal femoral osteotomy during stage I of LCPD the fragmentation stage may be bypassed partially or completely and the chances of a good outcome appear to be very good if fragmentation is bypassed.

LEVEL OF EVIDENCE

Level II Prognostic Study.

Assessing the reliability of the modified Gartland classification system for extension-type supracondylar humerus fractures

PURPOSE

The Gartland extension-type supracondylar humerus (SCH) fracture is the most common paediatric elbow fracture. Treatment options range from nonoperative treatment (taping or casting) to operative treatments (closed reduction and percutaneous pinning or open reduction). Classification variability between surgeons is a potential contributing factor to existing controversy over treatment options for type II SCH fractures. This study investigated levels of agreement in extension-type SCH fracture classification using the modified Gartland classification system.

METHODS

A retrospective review was conducted on 60 patients aged between two and 12 years who had sustained an extension-type SCH fracture and received operative or nonoperative treatment at a tertiary children's hospital. Baseline radiographs were provided, and surgeons were asked to classify the fractures as type I, IIA, IIB or III according to the modified Gartland classification. Respondents were then asked to complete a second round of classifications using reshuffled radiographs. Weighted kappa values were calculated to assess interobserver and intraobserver levels of agreement.

RESULTS

In all, 21 paediatric orthopaedic surgeons responded to the survey and 15 completed a second round of ratings. Interobserver agreement for classification based on the Gartland criteria between surgeons was substantial with a kappa of 0.679 (95% confidence interval (CI) 0.501 to 0.873). Intraobserver agreement was substantial with a kappa of 0.796, (95% CI 0.628 to 0.864).

CONCLUSION

Radiographic classification of extension-type SCH fractures demonstrated substantial agreement both between and within surgeon raters. Therefore, classification variability may not be a major contributing factor to the treatment controversy for type II SCH fractures and treatment variability may be due to differences in surgeon preferences.

LEVEL OF EVIDENCE

III.

The Pathogenesis and Treatment of Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes disease is a childhood hip condition in which the blood supply to the capital femoral epiphysis is interrupted, causing osteonecrosis and chondronecrosis that lead to progressive deformity of the femoral head and secondary degenerative osteoarthritis in later life. The etiology of Legg-Calvé-Perthes disease remains unclear, with both biological and mechanical factors playing important roles in the pathogenesis of the condition. The treatment of Legg-Calvé-Perthes disease remains controversial but is dependent on several salient factors, including the age at clinical onset, the extent of epiphyseal involvement, the stage of the disease, and the degree of femoral head deformity. The literature supports operative containment treatment in the early stage of disease. Such treatment has led to improved femoral head sphericity with better patient outcomes in multicenter prospective cohort studies. The number of hips that need to be treated operatively in order to achieve a modest treatment effect remains high. Multicenter prospective cohort studies have shown that 6 to 7 patients need to be managed to create 1 spherical femoral head that would not have otherwise occurred.

Role of Advanced Imaging in the Diagnosis and Management of Active Legg-Calvé-Perthes Disease

Since the first description of Legg-Calvé-Perthes disease a century ago, the diagnosis, staging, prognosis, and treatment decisions have been based on plain radiographs. The goal of treatment is prevention of femoral head deformity, yet radiographic prognostic classifications are applied in the fragmentation stage, often after deformity occurs. These classifications are assigned too late in the progression of the disease to maximize the effects of intervention. Thus, alternative mechanisms to determine femoral head involvement earlier in the disease course are warranted. Increasingly, MRI has been used in the study of the disease. Gadolinium-enhanced and diffusion-weighted MRI has shown promising results that correlate with radiographic classifications and the early radiographic outcome. Advanced imaging has improved the assessment of hinge abduction, yet the exact definition remains controversial. The role of imaging in the management of Legg-Calvé-Perthes disease is rapidly evolving. New or refined imaging techniques may eventually allow earlier prognosis and treatment.

Diagnosing slipped capital femoral epiphysis amongst various medical specialists

PURPOSE

To evaluate sensitivity, specificity and accuracy of a radiographic slipped capital femoral epiphysis (SCFE)-diagnosis among medical specialists.

METHODS

Three paediatricians, three paediatric radiologists and three paediatric orthopaedic surgeons completed two rounds of a survey of anteroposterior and frog-leg lateral radiographs of patients with a diagnosis of SCFE (25), femoroacetabular impingement (four), Legg-Calvé-Perthes (11) or no hip pathology (ten). Intra- and interobserver agreement among specialties regarding the diagnosis of a SCFE were assessed using Cohen's kappa coefficient (κ). Diagnostic accuracy of SCFE relative to the benchmark, a combination of the radiographic diagnosis based on Klein's line, clinical symptoms and surgical treatment, was assessed computing sensitivity, specificity and accuracy.

RESULTS

Intraobserver agreement between the surveys was moderate among paediatricians (κ-range, 0.44 to 0.52), moderate to almost perfect among orthopaedic surgeons (κ-range, 0.79 to 0.88) and almost perfect among paediatric radiologists (κ-range, 0.83 to 1.00). Interobserver agreement for survey 1 and 2 was slight among paediatricians (mean κ, 0.19), substantial among orthopaedic surgeons (mean κ, 0.77) and almost perfect among paediatric radiologists (mean κ, 0.86). Sensitivity of SCFE-diagnosis was high among radiologists and orthopaedic surgeons (88% to 100% for both specialties), but lower for paediatricians (24% to 76%). Specificity was high among radiologists and orthopaedic surgeons (72% to 84%), however, variable among paediatricians (56% to 80%). Accuracy of a SCFE-diagnosis was highest in radiologists (84% to 92%), followed by orthopaedic surgeons (80% to 88%) and paediatricians (48% to 78%).

CONCLUSION

SCFE can be detected on radiographs by different medical specialties. Intra- and interobserver agreement, specificity, sensitivity and accuracy for radiographic SCFE-diagnosis amongst paediatric radiologists and orthopaedic surgeons are better than that of general paediatricians.

LEVEL OF EVIDENCE

II.

MRI appearance in the early stage of Legg-Calvé-Perthes disease to predict lateral pillar classification: A retrospective analysis of the labral horizontalization

BACKGROUND

The Herring lateral pillar classification is widely used for the classification of Legg-Calvé-Perthes disease, but is not applied at the early stage of Legg-Calvé-Perthes disease because it is typically applied at the late fragmentation stage. The purpose of this study was to investigate the correlation between the early appearance on magnetic resonance imaging of the acetabular labrum and lateral pillar involvement in Legg-Calvé-Perthes disease.

METHODS

Non-contrast magnetic resonance images of 26 hips in 25 children with early-stage Legg-Calvé-Perthes disease were retrospectively reviewed. The extent of labral horizontalization was quantitatively evaluated with a new method, the labral angle, on T2*-weighted magnetic resonance images. A small labral angle indicates strong labral horizontalization. Calculation of the teardrop distance and acetabular head index on radiographs was modified for application to magnetic resonance imaging, and the extent of cartilaginous lateral subluxation (cartilaginous tear drop distance) and cartilaginous lateral extrusion (cartilaginous acetabular head index) were evaluated. The outcome measure was the lateral pillar classification.

RESULTS

There were statistically significant correlations between the labral angle and the cartilaginous tear drop distance (p = 0.002, ɤ = -0.58) and the cartilaginous acetabular head index (p < 0.001, ɤ = 0.65) on magnetic resonance images. The labral angle was small in order of groups C, B, and A, and there were significant differences between groups A and C (p < 0.001) and B and C (p = 0.006).

CONCLUSION

Greater labral horizontalization observed on magnetic resonance imaging at the early stage of Legg-Calvé-Perthes disease correlated with strong cartilaginous lateral subluxation and extrusion, and with increased lateral pillar collapse at the maximum fragmentation stage. Our finding suggests that a quantitative evaluation of labral horizontalization using magnetic resonance imaging in the early-stage of Legg-Calvé-Perthes disease can predict the later lateral pillar classification.

eIF2α signaling regulates ischemic osteonecrosis through endoplasmic reticulum stress

Osteonecrosis of the femoral head (ONFH) primarily results from ischemia/hypoxia to the femoral head, and one of the cellular manifestations is the endoplasmic reticulum (ER) stress. To understand possible linkage of ischemic osteonecrosis to the ER stress, a surgery-induced animal model was employed and salubrinal was administered to evaluate the role of ER stress. Salubrinal is a synthetic chemical that inhibits de-phosphorylation of eIF2α, and it can suppress cell death from the ER stress at a proper dose. The results indicated that the ER stress was associated with ONFH and salubrinal significantly improved ONFH-induced symptoms such as osteonecrosis, bone loss, reduction in vessel perfusion, and excessive osteoclastogenesis in the femoral head. Salubrinal also protected osteoblast development by upregulating the levels of ATF4, ALP and RUNX2, and it stimulated angiogenesis of endothelial cells through elevating ATF4 and VEGF. Collectively, the results support the notion that the ER stress is an important pathological outcome in the surgery-induced ONFH model, and salubrinal improves ONFH symptoms by enhancing angiogenesis and bone healing via suppressing the ER stress.

Assessment of Femoral Head Revascularization in Legg-Calvé-Perthes Disease Using Serial Perfusion MRI

BACKGROUND

Legg-Calvé-Perthes disease is a juvenile form of osteonecrosis of the femoral head. The purpose of this study was to use serial perfusion magnetic resonance imaging (MRI) to determine the pattern and rate of revascularization of the femoral heads of patients with the active stage of Legg-Calvé-Perthes disease.

METHODS

We performed a prospective study of 29 patients (30 hips) with a mean age (and standard deviation) of 8.4 ± 1.9 years who were diagnosed with Waldenström Stage-1 or 2 Legg-Calvé-Perthes disease. All patients had ≥2 perfusion MRIs, and 21 patients (22 hips) had ≥3. Perfusion percentages of the femoral epiphyses were measured by 2 independent observers. Statistical analyses included calculation of the intraclass correlation coefficient, the paired t test, the Mann-Whitney U test, and the Kruskal-Wallis test.

RESULTS

Initial perfusion MRIs showed the percent perfusion in the affected femoral heads to range from 5% to 70%. The average percent perfusion (and standard deviation) was 35% ± 16% on the first MRI, which increased to 77% ± 14% on the follow-up MRI acquired at an average of 10.5 ± 2.9 months later (p < 0.01). Serial assessment showed a general pattern of revascularization starting from the periphery of the posterior, lateral, and medial aspects of the femoral epiphysis and converging toward the anterocentral region. The average rate of revascularization was 4.9% ± 2.3% per month with a wide range among the patients (0.6% to 10.4% per month).

CONCLUSIONS

Revascularization of the necrotic femoral head increased over time in a horseshoe pattern, starting from the posterior, lateral, and medial aspects of the femoral epiphysis. The rate of revascularization was highly variable among patients.

LEVEL OF EVIDENCE

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

Knee loading protects against osteonecrosis of the femoral head by enhancing vessel remodeling and bone healing

Osteonecrosis of the femoral head is a serious orthopedic problem. Moderate loads with knee loading promote bone formation, but their effects on osteonecrosis have not been investigated. Using a rat model, we examined a hypothesis that knee loading enhances vessel remodeling and bone healing through the modulation of the fate of bone marrow-derived cells. In this study, osteonecrosis was induced by transecting the ligamentum teres followed by a tight ligature around the femoral neck. For knee loading, 5 N loads were laterally applied to the knee at 15 Hz for 5 min/day for 5 weeks. Changes in bone mineral density (BMD) and bone mineral content (BMC) of the femur were measured by pDEXA, and ink infusion was performed to evaluate vessel remodeling. Femoral heads were harvested for histomorphometry, and bone marrow-derived cells were isolated to examine osteoclast development and osteoblast differentiation. The results showed that osteonecrosis significantly induced bone loss, and knee loading stimulated both vessel remodeling and bone healing. The osteonecrosis group exhibited the lowest trabecular BV/TV (p b 0.001) in the femoral head, and lowest femoral BMD and BMC (both p b 0.01). However, knee loading increased trabecular BV/TV (p b 0.05) as well as BMD (pb 0.05) and BMC (p b 0.01). Osteonecrosis decreased the vessel volume (pb 0.001), vessel number (pb 0.001) and VEGF expression (p b 0.01), and knee loading increased them (pb 0.001, pb 0.001 and p b 0.01). Osteonecrosis activated osteoclast development, and knee loading reduced its formation, migration, adhesion and the level of “pit” formation (pb 0.001, pb 0.01, pb 0.001 and pb 0.001). Furthermore, knee loading significantly increased osteoblast differentiation and CFU-F (both p b 0.001). A significantly positive correlation was observed between vessel remodeling and bone healing (both p b 0.01). These results indicate that knee loading could be effective in repair osteonecrosis of the femoral head in a rat model. This effect might be attributed to promoting vessel remodeling, suppressing osteoclast development, and increasing osteoblast and fibroblast differentiation. In summary, the current study suggests that knee loading might potentially be employed as a non-invasive therapy for osteonecrosis of the femoral head.