The Sphericity Deviation Score

Siddesh, N. D.; Shah, Hitesh; Tercier, Stéphane; Pai, Harish; Nair, Sreekumaran; Joseph, Benjamin

doi:10.1097/bpo.0000000000000170

Cited by 23 publications

(27 citation statements)

References 17 publications

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“…However, it can be ambiguous in highly deformed femoral heads. In another study by the same group, the reference points were referred to as the medial and lateral margins of the growth plate 5 . Furthermore, other investigators have defined these points as a few millimeters above the margin of the growth plate.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to the radiation exposure, the conventional method has additional drawback. The reference points of the femoral head have not been clearly described or inconsistently described in previous studies 4,5 …”

mentioning

confidence: 96%

“…The sphericity deviation score (SDS) is a validated radiographic measure that quantifies the severity of femoral head deformity after the healed stage of LCPD, as a continuous numerical value 4 . The SDS is increasingly being used as a tool to measure the outcomes of LCPD, instead of the Stulberg classification, in more studies 5–7 …”

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confidence: 99%

“…4 The SDS is increasingly being used as a tool to measure the outcomes of LCPD, instead of the Stulberg classification, in more studies. [5][6][7] The conventional method of SDS measurement requires the anteroposterior (AP) pelvis and frog-leg lateral radiographs covering both hips (ie, 2 AP pelvis views) to standardize the difference in radiographic magnification of the 2 views. This poses the issue of increased radiation exposure associated with 2 AP pelvis views in unilateral cases, and it also excludes patients who only had plain radiographs of the unilateral hip from research studies involving SDS measurements.…”

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confidence: 99%

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Reliability of the Modified Method for Sphericity Deviation Score Using Only the Involved Hip Radiographs in the Patients With Legg-Calve-Perthes Disease

Kang

Kak

Prasadh

et al. 2023

Journal of Pediatric Orthopaedics

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Background: The sphericity deviation score (SDS) is a validated radiographic outcome measure that quantifies the severity of the femoral head deformity in the healed stage of Legg-Calve-Perthes disease (LCPD). The current method requires radiographs of both hips regardless of unilateral involvement to standardize radiographic magnification. As LCPD affects the unilateral hip in 85% to 90% of cases, the current method imposes unnecessary radiation exposure to most of the patients and having to exclude patients from research studies who only had unilateral hip radiographs. We thus modified the SDS method to use unilateral hip radiographs. The purpose of this study was to investigate the reliability of the modified SDS method using the radiographs containing only one hip. Methods: This retrospective study involved 40 patients with LCPD with unilateral involvement in the healed stage of LCPD. We modified the SDS measurement method by using the distance between the teardrop and the lateral acetabulum for magnification correction and providing a clear anatomic description of reference points on the femoral head. Three independent observers performed measurements using radiographs containing the affected hip only (modified method) and both hips (conventional method). The intraclass correlation (ICC) estimates were calculated. To verify clinical relevance, the correlation of the SDS with the Stulberg classification and hip range of motion (ROM) were also investigated. Results: Measurements using the modified SDS showed excellent inter-/intra-observer ICCs (0.903 to 0.978). The ICCs between the modified and conventional methods were also excellent: 0.940 to 0.966 within the same observer and 0.897 to 0.919 between different observers. The modified SDS showed moderate-to-strong correlations with the Stulberg classification (Spearman ρ=0.650) and hip ROM (Pearson r=−0.661). Conclusion: The modified SDS measurement method showed excellent inter-/intra-observer reliability and moderate-to-strong correlations with the Stulberg classification and hip ROM. This method will help reduce unnecessary radiation exposure in patients with unilateral LCPD and prevent the exclusion of patients with unilateral radiographs from future research studies. Level of Evidence: Level III—diagnostic study.

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Section: Discussionmentioning

confidence: 99%

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confidence: 96%

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confidence: 99%

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confidence: 99%

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Reliability of the Modified Method for Sphericity Deviation Score Using Only the Involved Hip Radiographs in the Patients With Legg-Calve-Perthes Disease

Kang

Kak

Prasadh

et al. 2023

Journal of Pediatric Orthopaedics

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“…Sphericity Deviation Score is a measure for the sphericity of the femoral head [28]. A score up to 10 represents a very good, up to 30 a fair, and over 30 a non-satisfactory result.…”

Section: Methodsmentioning

confidence: 99%

Outcome of the modified Dunn procedure in severe chronic or acute on chronic slipped capital femoral epiphysis

et al. 2019

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BackgroundIn recent years, the modified Dunn osteotomy has gained popularity to treat slipped capital femoral epiphysis (SCFE) with various complication rates. Most studies included patients with different severities. This study aimed to determine (1) the radiological and clinical outcome, (2) the health-related quality of life, and (3) the incidence of avascular necrosis of the femoral head (AVN) in patients with severe chronic or acute on chronic SCFE treated by the modified Dunn procedure.MethodsOut of 150 patients with SCFE treated at our institution between 2001 and 2014, 15 patients (mean age 12.9 years (range 11.8–15)) were treated by the modified Dunn procedure. Eight SCFE were chronic and 7 acute on chronic. All slips were severe with a mean Southwick slip angle (SSA) of 67° (range 60–80). Radiographic and clinical outcomes were measured. Mean time of follow-up was 3.8 years (range 1–10).ResultsAnatomical reduction was achieved in all cases. Good radiological results according to the Stulberg Classification (grade 1 + 2) and the Sphericity Deviation Score (< 30) were found in 9 out of 13 patients at the last follow-up. Clinical and functional outcome analysis revealed good results in 8 out of 10 patients (Harris Hip Score > 80). The quality of life measured by the Nottingham Health Profile (NHP) was described good in 10 out of 10 patients. Four out of 15 patients developed an AVN.ConclusionsThe modified Dunn procedure has a great potential to restore proximal femur geometry in severe chronic or acute on chronic SCFE. It should be considered only if there is no other possibility to restore proximal femur geometry, as is the case in severe slips, due to the risk of AVN.

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

Ditmer,

Dwenger,

Jensen

et al. 2023

Journal Orthopaedic Research

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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.

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The Sphericity Deviation Score

Abstract: A reliable estimate of the outcome of LCPD at skeletal maturity can be made by computing the SDS as soon as the disease heals.

Cited by 23 publications

References 17 publications

Reliability of the Modified Method for Sphericity Deviation Score Using Only the Involved Hip Radiographs in the Patients With Legg-Calve-Perthes Disease

Reliability of the Modified Method for Sphericity Deviation Score Using Only the Involved Hip Radiographs in the Patients With Legg-Calve-Perthes Disease

Outcome of the modified Dunn procedure in severe chronic or acute on chronic slipped capital femoral epiphysis

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

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