Vibratory coherence as an alternative to radiography in assessing bone healing after osteodistraction

Distraction osteogenesis is used in orthopedics to lengthen bones by cutting or breaking the bone and gradually separating the two pieces as new bone fills the intervening space. There is a need for early assessment of the degree of bone healing that allows for normal functioning without unwanted side effects. This study compared different techniques used to evaluate the degree of bone healing during mandibular osteodistraction in 21 rabbits. For each rabbit, the mandible was cut in a surgical procedure and then 72 h later distraction began at a rate of 3 mm per day. Bone formation at the distraction site was assessed by in vivo photodensitometry on head radiographs, an in vivo (nondestructive) vibratory coherence test across the distraction site, a postmortem, ex vivo (destructive) three-point bending mechanical test, and by postmortem, ex vivo (destructive) histological examination. Statistical analyses included analysis of variance and correlation coefficient tests. The findings revealed that the results of bone photodensity and the mechanical three-point test are highly and positively correlated with the results of the vibration test. The use of the vibration test may provide a substitute for or augment the routine use of radiography for in vivo evaluation and monitoring of bone healing.