Inter- and Intra-observer reliability of the pixel value ratio, Ru Li's and Donnan's classifications of regenerate quality in pediatric limb lengthening

Objective: The objective of this study is to determine the inter- and intra-observer reliabilities of three regenerate classifications (pixel value ratio [PVR], Ru Li and Donnan) in pediatric patients undergoing femoral or tibial distraction osteogenesis (DO). Methods: One hundred and forty regenerate radiographs (12 consecutive patients) were analyzed by using two observers using each classification system at two-time points. Inter and intra-observer reliabilities were calculated. Results: PVR and Ru Li demonstrated good, and Donnan demonstrated moderate to good inter- and intra-observer reliability. Two regenerate fractures occurred. Conclusion: Each classification can be reliably applied to pediatric DO. The PVR method of regenerate evaluation is ideal as it is simple and objective and can be used with readily available imaging software. The regenerate fractures identified in this study occurred in patients with longitudinal limb deficiency.