Departments of Orthopedic Surgery (E.N.N., P.E.M., G.B., and Y.-J.K.) and Radiology (S.D.B.), Boston Children's Hospital, Boston, Massachusetts.
Department of Mechanical and Industrial Engineering and Department of Bioengineering, Northeastern University, Boston, Massachusetts.
J Bone Joint Surg Am. 2018 Jan 3;100(1):66-74. doi: 10.2106/JBJS.17.00377.
Increased mechanical load secondary to a large body mass index (BMI) may influence bone remodeling. The purpose of this study was to investigate whether BMI is associated with the morphology of the proximal part of the femur and the acetabulum in a cohort of adolescents without a history of hip disorders.
We evaluated pelvic computed tomographic (CT) images in 128 adolescents with abdominal pain without a history of hip pathology. There were 44 male patients (34%) and the mean patient age (and standard deviation) was 15 ± 1.95 years. The alpha angle, head-neck offset, epiphysis tilt, epiphyseal angle, and epiphyseal extension were measured to assess femoral morphology. Measurements of acetabular morphology included lateral center-edge angle, acetabular Tönnis angle, and acetabular depth. BMI percentile, specific to age and sex according to Centers for Disease Control and Prevention growth charts, was recorded.
BMI percentile was associated with all measurements of femoral morphology. Each 1-unit increase in BMI percentile was associated with a mean 0.15° increase in alpha angle (p < 0.001) and with a mean 0.03-mm decrease in femoral head-neck offset (p < 0.001). On average, a 1-unit increase in BMI percentile was associated with a 0.0006-unit decrease in epiphyseal extension (p = 0.03), a 0.10° increase in epiphyseal angle (p < 0.001), and a 0.06° decrease in tilt angle (p = 0.02; more posteriorly tilted epiphysis). There was no detected effect of BMI percentile on acetabular morphology including lateral center-edge angle (p = 0.33), Tönnis angle (p = 0.35), and acetabular depth (p = 0.88).
Higher BMI percentile was associated with increased alpha angle, reduced head-neck offset and epiphyseal extension, and a more posteriorly tilted epiphysis with decreased tilt angle and increased epiphyseal angle. This morphology resembles a mild slipped capital femoral epiphysis deformity and may increase the shear stress across the growth plate, increasing the risk of slipped capital femoral epiphysis development in obese adolescents. BMI percentiles had no association with measurements of acetabular morphology. Further studies will help to clarify whether obese asymptomatic adolescents have higher prevalence of a subclinical slip deformity and whether this morphology increases the risk of slipped capital femoral epiphysis and femoroacetabular impingement development.
由于体重指数（BMI）较大而导致的机械负荷增加可能会影响骨骼重塑。本研究旨在探讨 BMI 是否与无髋关节疾病病史的青少年股骨近端和髋臼的形态有关。
我们评估了 128 例有腹痛但无髋关节病史的青少年的骨盆 CT 图像。其中男性 44 例（34%），患者平均年龄（标准差）为 15 ± 1.95 岁。测量 alpha 角、股骨头颈偏移、骨骺倾斜角、骨骺角和骨骺延伸来评估股骨形态。髋臼形态的测量包括外侧中心边缘角、髋臼 Tönnis 角和髋臼深度。记录 BMI 百分位数，根据疾病控制和预防中心的生长图表，针对年龄和性别进行具体分类。
BMI 百分位数与股骨形态的所有测量值均相关。BMI 百分位数每增加 1 个单位，alpha 角平均增加 0.15°（p < 0.001），股骨头颈偏移平均减少 0.03mm（p < 0.001）。平均而言，BMI 百分位数增加 1 个单位，骨骺延伸减少 0.0006 个单位（p = 0.03），骨骺角增加 0.10°（p < 0.001），倾斜角减少 0.06°（p = 0.02；骨骺更向后倾斜）。BMI 百分位数对髋臼形态无影响，包括外侧中心边缘角（p = 0.33）、Tönnis 角（p = 0.35）和髋臼深度（p = 0.88）。
较高的 BMI 百分位数与 alpha 角增加、股骨头颈偏移和骨骺延伸减少以及骨骺更向后倾斜、倾斜角减小和骨骺角增大有关。这种形态类似于轻度股骨颈骨骺滑脱畸形，可能会增加生长板上的剪切力，从而增加肥胖青少年发生股骨颈骨骺滑脱的风险。BMI 百分位数与髋臼形态的测量值无关。进一步的研究将有助于阐明肥胖无症状青少年是否有更高的亚临床滑脱畸形患病率，以及这种形态是否会增加股骨颈骨骺滑脱和股骨髋臼撞击症的发病风险。
