Service of Pediatric Orthopedics, Department of Child and Adolescent, University Hospitals of Geneva, 6, rue Willy Donz´e, 1211 Geneva 14, Switzerland.
J Bone Joint Surg Am. 2012 Feb 1;94(3):208-16. doi: 10.2106/JBJS.K.00420.
Leg or ankle fractures occur commonly in the pediatric population and are primarily treated with closed reduction and cast immobilization. The most predictable consequences of immobilization and subsequent weight-bearing restriction are loss of bone mineral mass, substantial muscle atrophy, and functional limitations. The purposes of this study were to determine if lower-limb fractures in adolescents are associated with abnormal bone mineral density or content at the time of fracture, and to quantify bone mineral loss at various sites due to cast-mediated immobilization and limited weight-bearing.
We recruited fifty adolescents aged ten to sixteen years who had undergone cast immobilization for a leg or ankle fracture. Dual x-ray absorptiometry scans of the total body, lumbar spine, hip, leg, and calcaneus were performed at the time of fracture and at cast removal. Patients with a fracture were paired with healthy controls according to sex and age. Values at baseline and at cast removal, or at equivalent time intervals in the control group, were compared between groups and between the injured and uninjured legs of the adolescents with the fracture.
At the time of fracture, there were no observed differences in the bone mineral density or bone mineral content Z-scores of the total body or the lumbar spine, or in the bone mineral density Z-scores of the calcaneus, between the injured and healthy subjects. At cast removal, bone mineral parameters on the injured side were significantly lower than those on the uninjured side in the injured group. Differences ranged from -5.8% to -31.7% for bone mineral density and from -5.2% to -19.4% for bone mineral content. During the cast period, the injured adolescents had a significant decrease of bone mineral density at the hip, greater trochanter, calcaneus, and total lower limb as compared with the healthy controls.
Lower-limb fractures are not related to osteopenia in adolescents at the time of fracture. However, osteopenia does develop in the injured limb during cast immobilization for fracture treatment. Further investigation is required to determine if the bone mineral mass will return to normal or if a permanent decrease is to be expected, which may constitute a hypothetical risk of sustaining a second fracture.
腿部或踝关节骨折在儿科人群中很常见，主要采用闭合复位和石膏固定进行治疗。固定和随后限制负重最可预测的后果是骨矿物质质量丢失、大量肌肉萎缩和功能受限。本研究的目的是确定青少年下肢骨折是否与骨折时骨矿物质密度或含量异常有关，并定量分析由于石膏固定和有限负重导致的各部位骨矿物质丢失。
我们招募了 50 名 10 至 16 岁因腿部或踝关节骨折接受石膏固定的青少年患者。在骨折时和去除石膏时对全身、腰椎、髋部、腿部和跟骨进行双能 X 线吸收法扫描。将骨折患者按性别和年龄与健康对照组进行配对。比较组间、骨折组和对照组在基线和去除石膏时（或对照组在等效时间间隔）的全身和腰椎骨矿物质密度或骨矿物质含量 Z 评分，以及骨折青少年受伤和未受伤腿部的骨矿物质密度 Z 评分。
在骨折时，受伤组和健康组的全身或腰椎骨矿物质密度或骨矿物质含量 Z 评分，以及跟骨骨矿物质密度 Z 评分均无差异。去除石膏时，骨折组受伤侧的骨矿物质参数明显低于未受伤侧。骨矿物质密度的差异范围为-5.8%至-31.7%，骨矿物质含量的差异范围为-5.2%至-19.4%。在石膏固定期间，与健康对照组相比，受伤青少年的髋部、大转子、跟骨和整个下肢的骨矿物质密度均显著下降。
下肢骨折在骨折时与青少年的骨质疏松无关。然而，在骨折治疗的石膏固定期间，受伤肢体确实会发生骨质疏松。需要进一步研究以确定骨矿物质质量是否会恢复正常，或者是否会出现永久性减少，这可能构成再次骨折的潜在风险。
