People with achondroplasia, the most common skeletal dyplasia (abnormality of the skeleton), have typical limb and spinal deformities. Often, corrective surgery for the spine is recommended, however, the authors of this study found that there have been no studies that measure the proportion of the spines in patients with achondroplasia.
The authors say that this is an important issue because placement of hardware to correct spinal deformations are based on the measurements of spines of normal proportions, which may cause problems in those people with shorter spines.
For this study, researchers used computed tomography imaging (CT scans) of 19 patients (14 men, 5 women, average age 32 years) with signs of spinal stenosis, narrowing of the spinal canal in one section. The researchers were looking at the dimensions of the pedicles, the bony prominences pointing out from the vertebrae, the small bones that make up the spine.
The results showed that the pedicles of the achondroplastic patients were considerably shorter than those in the control group, who were of normal size. As well, measurements of chord length were also shorter. The diameter of the pedicle, however, was found to be different in terms of how they are shaped and positioned. These findings are important, say the authors, because they indicate that surgeons need to be aware of these differences in order to choose the correct screws and the correct screw placement when performing spinal surgery.
The authors write, “Consideration of the unique aspects of the achondroplast spine could improve preoperative planning, and enhance both the effectiveness and safety of pedicle fixation in this population.”
They add that surgeons can measure patients before surgery using software similar to that used in the study or with traditionally printed CT scans.