What position should a patient be in when taking an impression for a custom LSO to treat L5-S1 spondylolisthesis?

When taking an impression for a custom lumbosacral orthosis (LSO) to treat L5-S1 spondylolisthesis, it is crucial to position the patient correctly to ensure optimal support and alignment. The correct position involves having the hips and knees in flexion.

This flexed position helps to relieve tension in the lumbar spine and allows for a more natural curvature, which is essential for maintaining appropriate spinal alignment. It mimics a position of ease and comfort for the patient while reducing strain on the lower back, thus providing an accurate impression of the contours of the lower back and pelvis. This is especially important in cases of spondylolisthesis where excessive lumbar lordosis can exacerbate the condition.

In contrast, positions such as standing upright or with hips and knees in extension could tighten the lumbar muscles and affect spinal alignment unfavorably, leading to an inaccurate impression. Sitting with a straight back may not adequately capture the necessary anatomical features needed for optimal orthotic design. Hence, the flexed position is preferred as it accommodates the needs of the patient and ensures better orthotic fit and function.