Novel method for determining bone dimensions relevant for longitudinal and transverse distraction osteogenesis and application in the human tibia and fibula

BACKGROUND

In distraction osteogenesis (DO) of long bones, new bone tissue is formed and distracted to lengthen limbs or reconstruct bone defects. However, certain anthropometric quantities relevant for biomechanical modelling of DO are unknown, such as areas where new bone tissue is formed. We developed a novel method to facilitate the determination of these distraction areas (DA), which we applied in the tibia and fibula of adults for longitudinal and transverse DO to advance knowledge of anatomical boundary conditions.

METHODS

CT data sets of 21 adult human tibiae and 24 fibulae were selected for investigation. Volumetric models were created utilizing image segmentation. The DA for longitudinal DO was determined in a CAD environment using the total bone cross section in the proximal, central and distal diaphysis of the tibia and fibula. Additionally, the medullary canal area was determined in the fibula. Furthermore, we measured the total DA and medullary canal DA for transverse distraction using a longitudinally split fibula with an osteotomy length of 8, 12, 16 and 20 cm. The osteotomy plane was oriented in medial and anteromedial direction. Finally, Spearman analyses were conducted to assess the correlation between bone length and DA.

RESULTS

For longitudinal DO, the mean total DAs were 878, 535 and 482 mm² in the tibia and 132, 153, 124 mm² in the fibula for the proximal, central and distal diaphysis, respectively. Regarding transverse distraction, the mean total DAs for a medial and anteromedial osteotomy plane orientation were 962, 1423, 1868 and 2306 mm² as well as 925, 1387, 1844, 2279 mm² for an osteotomy length of 8, 12, 16 and 20 cm, respectively. Weak, positive, and non-significant correlations were observed when correlating bone length and DA in the tibia and fibula.

CONCLUSIONS

Quantification of DAs and hence distracted callus tissue in DO advances anatomical knowledge and improves biomechanical modelling by adding a parameter which cannot be approximated based on bone length.