Blocking screws for alignment control in intramedullary limb lengthening.

Simultaneous deformity correction in the frontal and sagittal plane becomes more and more an important part of intramedullary lengthening to avoid further operative procedures. Such as in fracture treatment blocking screws can be used for alignment control if osteotomy is performed in the metaphyseal bone. 31 intramedullary lengthening procedures between 2009 and 2011 were retrospectively analysed for precision of simultaneous deformity correction. The average planned correction to the HKA was 2.4° (0.1°-8.0°) and the final results after lengthening deviated an average of 1.7° (0.0°-8.1°) from the planning. With blocking screws a higher degree of deformity (mean 3.2° vs. 1.7°; p<0.05) was corrected with a slightly higher precision (mean 1.5° vs. 1.9°; p=0.48) compared to patients without blocking screws. Placed on the concave side of the deformity blocking screws are a helpful tool to successfully address leg length discrepancy and other deformities with one single operation.