Thiel-fixation preserves the non-linear load-deformation characteristic of spinal motion segments, but increases their flexibility

► Spinal calf segments were biomechanically tested unfixed and after Thiel fixation. ► The range of motion and neutral zone were determined in the three anatomical planes. ► Thiel fixation maintains the non-linear load-deformation characteristic but increases the range of motion. ► Thiel fixation is superior to Formalin fixation, but fresh specimens are the best.