Introduction: It is unknown what effect distraction osteogenesis has on bone blood flow to the affected limb. Our study analyzed in vivo measurement of tibial blood flow during distraction osteogenesis using Doppler ultrasonography.

Materials and Methods: Blood flow was measured in the femoral artery, with Doppler ultrasonography in five people treated with bi-focal tibial distraction osteogenesis. The normal leg was used as the control to correct for differences in cardiac output. Measurements for each leg were taken and means recorded preoperatively, at 1 week postoperatively, and at subsequent intervals up to 6 months.

Results: Preoperative blood flow varied from 0.5 – 2.25. All treated legs demonstrated increases in flow from 2.25 – 5.75, with peaks in the first weeks following osteotomy. Significant increases in blood flow during treatment with distraction osteogenesis, confirming previous experimental studies.

Discussion: Blood flow plays a significant role in the successful outcome of this treatment. Compression of the non-union at the time of peak blood flow gives more reliable union than bone transport methods, where docking takes place when blood flow has returned towards the control limb.

Introduction: The radiographic criteria for successful lumbar arthrodesis remains controversial. Plain radiographs including flexion-extension views are commonly used to assess fusion, but there is disagreement on the degree of apparent motion that is significant. Helical CT assessment of bridging bone between vertebrae is considered to be the most accurate method currently available. This study compared the use of plain radiographs including flexion-extension views with helical CT scans in the assessment of lumbar interbody fusion.

Methods: Plain radiographs (including flexion-extension views) and helical CT scans were performed on 32 patients (47 levels) five years after ALIF using carbon fibre cages and autologous bone. A radiologist assessed fusion utilising the Hutter method to detect movement, whilst a spinal surgeon measured movement in degrees using the Simmons method. Helical CT scans (with sagittal and coronal reformatting) were assessed for the presence of bridging trabecular bone.

Results: The radiographic fusion rate was 85% based on the presence of bridging bone, and also 85% with the Hutter method. The fusion rate was 74% when movement of at least two degrees was considered significant, but was 98% with the five degrees cut off adopted by the FDA. Fusion as determined by the presence of bridging trabeculae on helical CT Scans occurred in 67%. Concordance rates were as follows: between plain films and helical CT, 69.5%; between Hutter method and plain films, 76%; between Simmon’s method (two degrees) and helical CT, 67%; and between Simmon’s method with the FDA cut-off of five degrees and CT, 65%.

Discussion: The assessment of fusion with radiographs appears to be unreliable. The use of plain films and flexion-extension radiographs clearly overestimated the actual fusion rates. Furthermore, there was low concordance between these methods and the more reliable helical CT. This disparity between fusion rates from radiographs and with helical CT supports the view that plain radiographs, including flexion-extension films are of limited value in the assessment of spinal arthrodesis.