The specific dysfunction is labeled by the position the zygapophyseal joint is stuck in and the asymmetrical position the segment assumes when it is moved in the direction of restricted motion. The three-dimensional motion restricted at the vertebral segment is diagonally opposite to the diagnostic label given to the dysfunction. There are four potential positional diagnoses for single quadrant limitations of segmental motion: ERSR, ERSL, FRSR and FRSL. These diagnoses are based upon osteopathic terminology and are commonly used in muscle energy and joint mobilization systems of treatment.
FRSL - Flexed, Rotated and Side bent to the Left
This term describes the asymmetrical movement of the superior vertebra during extension of the segment if the right zygapophyseal joint is unable to close (the inferior articular process of the superior vertebra is unable to glide inferior on the superior process of the inferior vertebra). If the right zygapophyseal joint is stuck in an open or flexed position (it can not extend), the superior vertebra will side bend to the left as the segment is extended. In accordance with Law II, the superior vertebra will also rotate to the left. The left rotation of the superior vertebra will cause its left transverse process to move posterior in relation to the right transverse process and the left transverse process below. The posterior position of the left transverse process of the superior vertebra can be palpated with the patient in an extended spinal posture. When a zygapophyseal joint is unable to close with extension, the posterior transverse process will be on the opposite side as the zygapophyseal joint that is stuck. The positional diagnosis would indicate that the superior vertebra is Flexed, Rotated and Side bent to the Left. This dysfunction at the L5S1 segment would be recorded as L5 FRSL. The restricted motion at the segment is Extension, Rotation and Side bending to the Right. If using a direct treatment technique like muscle energy, the motion restricted will be the three-dimensional direction the dysfunctional segment is moved toward during treatment.
If a zygapophyseal joint is unable to open or close, then segmental motion will be restricted in two diagonally opposite quadrants. For example, evaluation procedures may reveal an ERSR and a FRSL at the same segment if the left zygapophyseal joint is unable to flex or extend due to osseous fusion or capsular fibrosis. A right posterolateral disc protrusion may produce apparent ERSL and FRSL positional diagnosis findings because it limits motion the ability of the superior vertebra to right side bend or right rotate in either a flexed or extended position.
