Abstract
Background:
Previous studies have established the relationship between changes in the femoral head epiphysis and prognosis of Legg-Calvé-Perthes disease (LCPD), whereas the clinical significance of metaphyseal changes remains to be elucidated. This study aims to investigate the correlation between the type of metaphyseal changes and disease severity, as well as determine whether it is associated with the prognosis of LCPD based on radiographic outcomes after undergoing containment therapy.
Methods:
A retrospective analysis was conducted on the records of 105 patients with unilateral LCPD who underwent containment treatment. Three common types of metaphyseal changes were assessed using anteroposterior and frog-leg lateral radiographs, and the correlation between these change types and other clinical prognostic indicators was further analyzed. Univariate and multivariate logistic regression models were used to analyze potential risk factors affecting femoral head shape in children over 6 years of age, based on the Sphericity Deviation Score (SDS) was measured after epiphyseal healing, including age, stage at diagnosis, lateral pillar classification, Catterall classification, type of metaphyseal changes, and treatment method.
Results:
A total of 105 patients (mean age at diagnosis 6.8 y) were included. Among them, 6 showed no metaphyseal reaction, 45 had localized osteopenia, 29 exhibited cystic changes, and 25 presented with diffuse reactions. Of these patients, 40 received conservative treatment and 65 underwent surgeries. Surgical intervention significantly improved femoral head containment (extrusion index: 29.5±7.9 to 7.6±5.6, P<0.001). The frequency of spherical femoral heads after healing differed significantly among metaphyseal groups (P<0.001), with the diffuse reaction group showing a higher rate of nonspherical femoral heads and significantly greater metaphyseal widening. Patients under 6 years had better outcomes than older children (88.9% vs. 56.5%, P=0.001). In patients over 6 years, multivariate analysis identified lateral pillar collapse (OR: 4.63, P=0.023) and diffuse metaphyseal reactions (OR: 7.31, P=0.009) as risk factors of poor femoral head sphericity. Cystic changes were not significantly associated with poor outcomes.
Conclusion:
Diffuse metaphyseal reaction is indicative of more severe condition in patients with LCPD, as well as its serve as a strong predictor of poor prognosis in patients over 6 years old, whereas metaphyseal cysts are less significant in predicting femoral head shape.
Level of Evidence:
Level III—prognostic study.
Key Words: Legg-Calvé-Perthes disease, metaphyseal changes, prognostic factors, sphericity deviation score
Legg-Calvé-Perthes disease (LCPD) is an idiopathic pediatric hip disorder characterized by necrosis of the femoral head epiphysis due to an interruption in blood supply.1 The primary objective of LCPD management is to prevent femoral head deformity, maintain hip joint congruity, and preserve good hip range of motion.2 Despite achieving containment of the femoral head by nonoperative and operative methods, some patients still develop a nonspherical femoral head and hip joint incongruity after the disease has healed, leading to an increased risk of secondary degenerative arthritis.3,4 Previous research has primarily focused on the changes in the femoral head epiphysis, utilizing several radiologic factors to predict the morphology of the hip joint at skeletal maturity, while some studies have also indicated that metaphyseal changes are associated with poor prognoses in LCPD patients.5–8 Catterall’s6 study identified diffuse metaphyseal reaction as a “head-at-risk sign.” Later, Smith et al7 proposed cystic metaphyseal change as an indicators of a poor prognosis. However, the prognostic value of these metaphyseal changes remains uncertain, as some studies have questioned whether they are reliable prognostic indicators.9–11 Moreover, the association between different types of metaphyseal changes and factors such as patient age, disease severity, and treatment outcomes is not understood.
The primary objective of this study is to explore the correlation between metaphyseal changes and initial radiologic indicators like age and disease severity in LCPD. Furthermore, it will determine whether these changes affect treatment outcomes, providing insights into their potential role as prognostic indicators and guiding clinical decision-making in the management of LCPD.
METHODS
This study was approved by our Ethics Review Committee. We study retrospectively analyzed the clinical and radiographic data of 197 patients with LCPD who were treated at our hospital between 2011 and 2021. The inclusion criteria were: (1) availability of complete radiographic data before and after treatment; (2) hips not enter the reossification stage at diagnosis, as classified by the modified Waldenström system12; and (3) follow-up until the healing stage postdiagnosis. Patients with bilateral involvement or femoral head epiphyseal dysplasia were excluded from the study.
Following their initial visit, all patients underwent immediate nonweight-bearing treatment, supported by either casting or bracing. For those with inadequate femoral head coverage, as indicated by pelvic AP views or Von-Rosen views (extrusion index >20%), triple pelvic osteotomy (TPO) or proximal femoral varus osteotomy (PFVO) was performed. For severe subluxation and preoperative evaluation suggests that a single pelvic osteotomy or PFVO is difficult to achieve satisfactory containment, we used Salter innominate osteotomy (SIO) or TPO combined with PFVO. All surgical procedures were carried out by the same surgeon. During follow-up, patients were permitted to bear weight only after pelvic radiographs confirmed sufficient new bone formation in the anterolateral epiphysis.
We reviewed serial radiographs for each child. According to descriptions of metaphyseal changes in the previous literature,7,12–14 we assessed 3 common types: type 1, characterized by no significant metaphyseal changes or localized irregular low-density changes (local osteoporosis);12 type 2, defined as round or oval cyst-like radiolucent lesions with clear boundaries observable on both AP and frog-leg lateral views (cystic change);7,14 and type 3, marked by extensive metaphyseal band-shaped zone of decalcification affecting more than 3/4 of the metaphyseal width beneath the growth plate on AP views, with anterior metaphyseal lager defects seen on lateral views (diffuse metaphyseal reaction)12,13 (Fig. 1). We followed up on the process of metaphyseal reaction repair and recorded the pattern of repair of defects on the anterior side of the epiphysis. One is that the metaphysis itself may undergo repair. Another approach is that the bone defect at the epiphyseal end is filled by ossification on the epiphyseal side. The extent of LCPD involvement was determined during the fragmentation stage using the Catterall classification system.15 Given the limitations of this system’s low interobserver reliability, we simplified it by merging Catterall Groups I and II into one category, and Groups III and IV into another, resulting in a more straightforward 2-group classification.16 We also use the lateral pillar classification developed by Herring et al,17 which divides the hips into 4 groups. For further analysis, we adopted a simplified 2-group classification, with groups A and B representing mild collapse, and groups B/C border and C representing severe collapse.18
FIGURE 1.
Three examples of different types of metaphyseal change on the anteroposterior and frog-lateral radiograph of the pelvis. (A, B) Local osteoporosis. (C, D) Cystic change. (E, F) Diffuse metaphyseal reaction.
At the final follow-up, we evaluated femoral head sphericity by measuring the Sphericity Deviation Score (SDS)19 on radiographs obtained after epiphyseal healing. The lower SDS indicates better femoral head sphericity, an SDS ≤10 suggests a spherical femoral head.20 We also measured the extrusion index of affected epiphysis, and the height and width of the bilateral epiphyses, the width of the metaphysis, and the length and width of the femoral necks, expressing these values as a percentage of the ratio of the affected side divided by the contralateral normal hip. All radiographic measurements were carefully performed by 2 senior authors. In cases of disagreement, the final consensus was reached through open discussion.
Analytical Methods
For correlation analysis, patients were categorized into 3 groups depending on the presence of type of metaphyseal changes. Weighted Kappa statistics were used to determine the inter-rater reliability for the types of metaphyseal changes, the lateral pillar classification, and the Catterall classification. We estimated the interclass correlation coefficient (ICC) values for the interobserver reliability of variables including SDS, epiphysis height, epiphysis width, metaphysis width, neck width, and neck height. One-way analysis of variance (ANOVA) and post-hoc tests were performed to evaluate whether statistically significant differences existed in mean values among the 3 independent groups based on the types of metaphyseal changes. Categorical variables were analyzed using the χ2 test or the Fisher exact test. Finally, univariate and multivariate logistic regression models were applied to analyze the clinical and radiologic factors that could potentially influence prognosis, based on femoral head sphericity after the healing stage. All statistical analyses were performed using IBM SPSS Statistics 26, with a P-value<0.05 considered statistically significant. Values are expressed as mean±SD.
RESULTS
A total of 105 patients with unilateral involvement were included in this study (89 males, 16 females). The age at diagnosis ranged from 2.5 to 13.0 years (mean: 6.8 y). The follow-up duration ranged from 31 to 141 months (mean: 5.2 y). The age at the final follow-up ranged from 7.6 to 22.1 years (mean: 12.0 y). According to the modified Waldenström classification,10 4 patients were diagnosed in stage Ia, 45 in stage Ib, 38 in stage IIa, and 18 in stage IIb. Forty patients were treated conservatively throughout, while 65 patients underwent surgery (39 underwent TPO, 18 PFVO, 6 combined TPO and PFVO, and 2 cases SIO combined with PFVO). Of these, 14 patients initially managed conservatively were converted to surgical treatment due to inadequate containment as indicated by an increased extrusion index.
The characteristics and radiologic outcomes of patients with different types of metaphyseal reactions included in this study are shown in Table 1. The weighted kappa values for interobserver reliability were 0.78 for the type of metaphyseal change, 0.84 for the lateral pillar classification, and substantial to almost perfect agreement. The weighted kappa for the interobserver reliability of the Catterall classification was 0.56, indicating moderate agreement. With regard to the outcome measures at after the disease healed (SDS, epiphysis height, epiphysis width, metaphysis width, neck width, and neck height), all variables showed excellent ICC values for interobserver reliability, showed excellent ICC values for interobserver reliability (range: 0.87 to 0.93).
TABLE 1.
Demographic Data and Outcomes of Healing Stage Based on Types of Metaphyseal Change in 105 Patients With Perthes Disease
| Variable | Type 1, n (%) | Type 2, n (%) | Type 3, n (%) | P |
|---|---|---|---|---|
| Age at onset (mean±SD) | 6.2±1.8 | 7.3±2.1 | 7.6±1.7 | 0.004 |
| Sex | 0.294 | |||
| Male | 45 (88.2) | 26 (89.7) | 19 (85.7) | |
| Female | 6 (11.8) | 3 (10.3) | 6 (14.3) | |
| Side | 0.844 | |||
| Left | 23 (45.1) | 11 (37.9) | 11 (44) | |
| Right | 28 (54.9) | 18 (62.1) | 14 (56) | |
| Stage at diagnosis | 0.027 | |||
| Ia | 3 (5.9) | 2 (6.9) | 0 | |
| Ib | 28 (54.9) | 8 (27.6) | 8 (28) | |
| IIa | 15 (29.4) | 15 (51.7) | 8 (32) | |
| IIb | 5 (9.8) | 4 (13.8) | 9 (36) | |
| Lateral pillar | 0.001 | |||
| A and B | 40 (78.4) | 19 (76) | 9 (36) | |
| B/C and C | 11 (21.6) | 6 (24) | 16 (64) | |
| Catterall group | 0.007 | |||
| I and II | 25 (49) | 7 (24.1) | 4 (16) | |
| III and IV | 26 (51) | 22 (75.9) | 21 (84) | |
| Treatment | < 0.001 | |||
| Nonoperative | 30 (58.8) | 5 (17.2) | 5 (20) | |
| Operative | 21 (41.2) | 24 (82.8) | 20 (80) | |
| Sphericity Deviation Score | < 0.001 | |||
| ≤10 | 44 (86.3) | 19 (65.5) | 8 (32) | |
| >10 | 7 (13.7) | 10 (34.5) | 17 (68) |
No metaphyseal change was observed in 6 patients, while the remaining patients exhibited varying degrees of metaphyseal radiolucency. In the fragmentation stage, a higher proportion of patients in the cystic group and diffuse reaction group had epiphyseal involvement >50% (Catterall III and IV) (75.9% and 84%, respectively, P=0.007). Among patients with diffuse metaphyseal reactions, 64% exhibited severe lateral pillar collapse (B/C border and C), and 60.9% had isolated ossification centers within the metaphyseal defects during the phase of repair of the metaphysis. After treatment, significant differences were observed in the frequency of spherical femoral heads (SDS <10) among patients with different types of metaphyseal changes (P<0.001) (Table 1). We found that the metaphysis of nonspherical femoral heads was significantly widened compared with spherical femoral heads (119.6%±11.1% vs. 110.5%±6.9%, P<0.001). And the patients with diffuse metaphyseal reactions show more significant metaphyseal widening as the disease progresses (Fig. 2).
FIGURE 2.
Mean percentage metaphyseal widening with 95% CIs through the disease stages between different types of metaphyseal changes. *indicates that the difference is statistically significant (P<0.05) compared with type 1. **indicates that the difference is statistically significant (P<0.05) compared with type 2.
When grouped by age, children under 6 years old were more likely to achieve satisfactory outcomes, whether treated conservatively or surgically (88.9% vs. 56.5%, P=0.001) (Table 2). Among patients over 6 years old, excluding those receiving conservative treatment, the extent of head involvement was milder (P=0.026), there were no significant differences in age (P=0.164), lateral pillar (P=0.235), and metaphyseal changes (P=0.286) between the different surgical groups. Surgical intervention resulted in a significant improvement in femoral head coverage (preoperative extrusion index: 29.5±7.9; final follow-up: 7.6±5.6; P<0.001).
TABLE 2.
Patient’s Radiographic Classification and Outcomes According to the Age Group
| Variable | ≤6 y (n=36) | >6 y (n=69) | P |
|---|---|---|---|
| Lateral pillar | 0.287 | ||
| A and B | 26 (72.2) | 42 (60.9) | |
| B/C and C | 10 (27.8) | 27 (39.1) | |
| Catterall group | 0.02 | ||
| I and II | 19 (52.8) | 20 (29) | |
| III and IV | 17 (47.2) | 49 (71) | |
| Type of metaphyseal changes | 0.014 | ||
| Type 1 | 23 (63.9) | 28 (40.6) | |
| Type 2 | 10 (27.8) | 19 (27.5) | |
| Type 3 | 3 (8.3) | 22 (31.9) | |
| Sphericity Deviation Score | 0.001 | ||
| ≤10 | 32 (88.9) | 39 (56.5) | |
| >10 | 4 (11.1) | 30 (43.5) |
On the basis of the univariate analysis for patients older than 6 years, variables influencing femoral head sphericity after epiphyseal healing included the simplified Catterall classification, simplified lateral pillar classification, treatment method, and type of metaphyseal changes (Table 3). In the multivariate regression model, greater severity of lateral pillar collapse was significantly associated with a decreased likelihood of maintaining femoral head sphericity (OR: 4.63; 95% CI: 1.24-17.29; P=0.023). Furthermore, compared with osteopenia, hips exhibiting diffuse metaphyseal reactions were more likely to develop a nonspherical femoral head (OR: 7.31; 95% CI: 1.65-32.5; P=0.009), whereas cystic changes did not increase this risk (OR: 3.48; 95% CI: 0.79-15.27; P=0.098).
TABLE 3.
Univariate Analysis: Discrete or Categorical Variables That Influenced the Sphericity Deviation Score at Healing Stage in Patients Over 6 Years Old
| Sphericity Deviation Score | Univariate analysis | ||||
|---|---|---|---|---|---|
| Variable | Category | ≤10 | >10 | OR (95% CI) | P |
| Age at diagnosis | N/A | 7.8±1.3 | 8.0±1.6 | 1.07 (0.77-1.49) | 0.669 |
| Stage of treatment | Ia | 4 (10.3) | 1 (3.3) | Ref | |
| Ib | 18 (46.2) | 9 (30) | 2.0 (0.19-20.61) | 0.56 | |
| IIa | 12 (30.8) | 12 (40) | 4.0 (0.39-41.23) | 0.244 | |
| IIb | 5 (12.8) | 8 (26.7) | 6.4 (0.55-74.89) | 0.139 | |
| Catterall group | I and II | 17 (43.6) | 3 (10) | Ref | |
| III and IV | 22 (56.4) | 27 (90) | 6.95 (1.8-26.84) | 0.005 | |
| Lateral pillar | A and B | 32 (82.1) | 10 (33.3) | Ref | |
| B/C and C | 7 (17.9) | 20 (66.7) | 9.14 (3.0-27.9) | <0.001 | |
| Methods of treatment | Nonoperative | 12 (30.8) | 3 (10) | Ref | |
| TPO | 14 (35.9) | 18 (60) | 5.1 (1.2-21.8) | 0.026 | |
| PFVO | 10 (25.6) | 4 (13.3) | 1.6 (0.3-8.9) | 0.591 | |
| Combine | 3 (7.7) | 5 (16.7) | 6.7 (1.0-45.0) | 0.052 | |
| Metaphyseal changes | Type 1 | 23 (59) | 5 (16.7) | Ref | |
| Type 2 | 10 (25.6) | 9 (30) | 4.14 (1.1-15.52) | 0.035 | |
| Type 3 | 6 (15.4) | 16 (53.3) | 12.27 (3.19-47.2) | <0.001 | |
N/A indicates not applicable.
The patients with diffuse metaphyseal reactions present also had more femoral neck shortening, and thickening after epiphysis healed (Table 4).
TABLE 4.
Comparisons of Radiographic Outcomes and Measurements By Types of Metaphyseal Change in Patients Over 6 Years Old
| Variable | Type 1, (n=28) | Type 2, (n=19) | Type 3, (n=22) |
|---|---|---|---|
| Sphericity Deviation Score* | |||
| ≤10 | 23 (82.1) | 10 (52.6) | 6 (27.3) |
| >10 | 5 (17.9) | 9 (47.4) | 16 (72.7) |
| Extrusion of the femoral epiphysis | 10.2±6.7 | 7.3±5.2 | 9.7±7.9 |
| Width of the femoral epiphysis | 112.6±9.2 | 115.4±9.9 | 121.7±11.0† |
| Height of the femoral epiphysis | 82.1±9.6 | 74.9±14.8 | 70.9±12.5† |
| Length of the femoral neck | 98.1±7.5 | 92.2±10.1 | 91.7±8.6† |
| Width of the femoral neck | 107.8±8.2 | 108.9±7.6 | 116.2±10.7†,‡ |
P<0.001 by χ2 test.
Indicate statistically significant difference compared with the type 1 group (P<0.05).
Indicate statistically significant difference compared with the type 2 group (P<0.05).
DISCUSSION
This study is the first to identify the correlation between metaphyseal response and age, Catterall classification, as well as lateral pillar classification. Patients exhibiting diffuse metaphyseal reactions also tended to have more severe disease. Furthermore, risk factor analysis clarified that among the various types of metaphyseal reactions, diffuse metaphyseal reaction is most indicative of a poor prognosis.
Previous reports have described various types of metaphyseal changes from a radiographic perspective.6–9,12,13 However, despite these descriptions, the lack of accurate and standardized classification systems has limited exploration of their prognostic value and impact on treatment decisions. In a study by Smith et al,7 all patients with unacceptable treatment outcomes exhibited distinct metaphyseal cystic changes. However, among the 72 hips with metaphyseal cysts, 26 also presented with additional features, such as a rarefied band directly beneath the growth plate or surrounding sclerosis. To simplify these classifications, Smith grouped all cyst-related reactions under a single “cystic” label. This simplified approach may overestimate the prognostic significance of metaphyseal cysts. Our evaluation showed that the majority of patients with cystic changes (19/29, 65.5%) still achieved acceptable outcomes (Fig. 3).
FIGURE 3.
Pelvic radiographs in a 6.1-year-old boy who underwent the triple pelvic osteotomy for the right hip with Perthes disease in stage IIb of the disease. (A, B) The appearance of metaphyseal cystic change in the right hip. (C, D) Radiographs made 3 years and 2 months after the osteotomy showing the healing of the disease and the spherical shape of the femoral head, SDS=9.2.
In addition, the extent of metaphyseal involvement should be considered in evaluating disease severity. Catterall suggested that diffuse metaphyseal reactions are more strongly associated with poor prognosis compared with localized reactions.6 However, other studies have argued that neither cystic changes nor diffuse metaphyseal reactions are definitive radiographic prognostic factors.10 Although Joseph described diffuse metaphyseal reactions as osteopenia involving the entire width of the metaphysis,12 it remains difficult to accurately distinguish diffuse reactions from more extensive focal osteopenia based solely on the width of metaphyseal changes seen on anteroposterior radiographs. A single 2-dimensional view cannot reliably capture the 3-dimensional pathology of the metaphysis. Diffuse metaphyseal reactions are different from osteoporosis, which may appear in various locations, are almost exclusively located on the anterior side of the metaphysis, involving the anterolateral cortex. Therefore, accurate assessment and differentiation of these distinct types of metaphyseal changes should be based on both frontal and lateral radiographic views in order to explore their potential relationship with disease prognosis.
The etiology of metaphyseal changes has not been elucidated. Previous studies suggested that metaphyseal lesions are part of the overall necrosis, occurring due to the interruption of the shared blood supply between the epiphysis and metaphysis.8 The metaphyseal changes correspond to the extent of epiphyseal involvement.21 We observed that both metaphyseal cysts and diffuse metaphyseal reactions were more prevalent in older patients who were diagnosed later, and were often classified as Catterall III or IV. Our findings also indicate that hips with diffuse metaphyseal reactions are more prone to severe lateral pillar collapse during the fragmentation stage. This suggests that LCPD hips with diffuse metaphyseal reactions are more vulnerable, with an increased risk of lateral pillar of epiphysis collapse. Therefore, we believe that the prolonged weight-bearing not only causes repeated mechanical damage to the epiphysis in the early stages of the disease,20 but also affects the metaphysis. The presence of such metaphyseal abnormalities, especially diffuse reaction, may further indicate more severe damage to the femoral head.
It is well established that the prognosis for patients aged 6 years or younger is generally favorable, as they have greater potential for femoral head remodeling and healing.2,17 When young patients have full head involvement and develop metaphyseal cysts, they can still achieve acceptable outcomes.8 This raises the question whether metaphyseal changes have prognostic value in younger patients. In the present study, the epiphyseal involvement was mild, and diffuse metaphyseal reactions were rare (8.3%) in most patients under 6 years old. Regardless of the type of metaphyseal reaction, 88.9% of these younger patients achieved satisfactory outcomes following containment treatment.
In a recent study, the authors suggested that resorption of the anterior femoral head and metaphysis can predict poor hip morphology at skeletal maturity in patients with lateral pillar B-type LCPD.22 In our study, a multivariate logistic regression model showed a strong association between diffuse metaphyseal reactions and the sphericity of the femoral head at the time of epiphyseal healing. The impact of anterior lateral metaphyseal bony defects on prognosis may be related to the pattern of repair.21 All patients with epiphyseal bone defects filled with ossification on the epiphyseal side ultimately had a nonspherical femoral head and presented as a step-like irregularity of the anterior lateral epiphyseal plate (Fig. 4). Furthermore, as the disease progresses, the blood supply to the metaphysis increases, and patients with diffuse metaphyseal reactions may exhibit adaptive responses to the disease, manifested as significant widening of the metaphysis.12 The extent of metaphyseal widening correlates quite closely with the extent to which the femoral head enlarges, and greater the degree of metaphyseal widening the poorer the final outcome.23,24 It may contribute to the poor prognosis associated with diffuse metaphyseal changes in LCPD.
FIGURE 4.
Pelvic radiographs in a 7.3-year-old boy who underwent the triple pelvic osteotomy for the right hip with Perthes disease in stage IIa of the disease. (A, B) The appearance of diffuse metaphyseal reaction in the right hip. (C, D) Radiographs of final follow-up made 5 years and 4 months after the osteotomy showing the disease healed with a nonspherical femoral head, SDS=32.2.
Previous studies have suggested that hips with cystic changes are twice as likely to have poor outcomes compared with those without such changes.7 However, our study found no significant association between metaphyseal cysts and femoral head shape after the disease healed. A magnetic resonance imaging study has confirmed that the “cyst” observed on radiographs may not be entirely located within the metaphysis. It may be a pseudocyst involving the epiphysis or epiphyseal plate. Compared with true cysts located entirely within the metaphysis, there is a higher likelihood of proximal femoral malformations occurring.25 There are significant differences in the observation of metaphyseal cysts on radiographs,5,14 and only histologic examination or MRI can distinguish between true and false cysts.25
This study has several limitations. First, as a small-scale retrospective study with varying treatment approaches, there may be selection bias. However, all treatments were based on the principle of containment, with the most appropriate treatment selected according to the patient’s specific circumstances. Currently, there is no conclusive evidence that surgical treatment is superior to conservative management.1,2,26 Second, our study endpoint was disease healing, however, some studies suggestion that spontaneous correction of proximal femoral anatomic abnormalities may still occur before skeletal maturity.20,27 Future research with extended follow-up to skeletal maturity and a larger sample size will be needed to assess whether metaphyseal changes are associated with growth disturbances in the proximal femur.
CONCLUSION
Diffuse metaphyseal reactions are indicative of more severe disease in patients with LCPD. For patients over 6 years old, this reaction serves as a strong predictor of poor prognosis, whereas metaphyseal cysts are less significant in predicting femoral head shape. Further studies are needed to observe physeal changes and the types of anterior metaphyseal defect repair by MRI or other advanced imaging techniques, providing deeper insights into the significance of metaphyseal reactions in LCPD.
ACKNOWLEDGMENT
The authors thank the National Natural Science Foundation of China for their support in the project (No. 82060396, No. 82160809).
Footnotes
Z.L. and C.L. contributed equally to this work.
Ethical statement: Approval from our institutional review board was obtained for this retrospective study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the Helsinki declaration and its later amendments or comparable ethical standards.
This work was supported by the National Natural Science Foundation of China (No. 82060396 and No. 82160809).
The authors declare no conflicts of interest.
Contributor Information
Zhenbiao Li, Email: lizhenbiao25@163.com.
Chenyang Li, Email: 2470094896@qq.com.
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Zhirui Hua, Email: 2377380818@qq.com.
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