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Surprising Amount of Bone Loss in Children After Orthopedic Surgery

Children who need orthopedic surgery of the lower extremity often end up in a cast for four to eight weeks. Immobilization with a non-weight bearing status can lead to bone loss. As a result of these factors, the risk of bone fracture goes up.

In this study, the amount of bone loss before and after immobilization is measured. Dual-photon dual energy X-ray absorptiometry (DXA) scans were taken just before surgery. The DXA was repeated within a week of cast removal or restarting weight bearing activities.

Children included in the study were between the ages of four and 18 years old. There was a wide range of diagnoses for which surgery was needed. Some children had Legg-Perthes disease, cerebral palsy, or spina bifida. Others had neuromuscular problems such as Charcot-Marie-Tooth disease or neuromuscular flatfoot.

The authors knew there would be bone loss. They were surprised by just how much bone loss occurred. In some cases, up to one-third of the bone mineral density was lost in the operated leg. The average bone loss was around 11.5 per cent.

Healthy children with good bone mineral density might be able to handle this much bone loss. But most of the children who are immobilized after orthopedic surgery have a chronic illness or disease. They are more likely to have decreased bone density from abnormal growth. The risk of bone fracture is much higher in this group.

The authors also report that recovering from bone loss in this population takes much longer than expected. Again, the risk of fracture is much higher during the months it takes to replace the bone loss.

The next step is to find ways to treat this problem. Right now, vitamin D, calcium supplements, and weight-bearing activities are used to support bone mineral density. More research is needed to identify ways to prevent the problem from occurring in the first place.

References: Elizabeth A. Szalay, MD, et al. Quantifying Postoperative Bone Loss in Children. In Journal of Pediatric Orthopaedics. April/May 2008. Vol. 28. No. 3. Pp. 320-323.

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