The patient lies supine with the knees and hips flexed to about forty-five degrees and the feet flat on the couch. He bends the knees up towards the chest, firmly clasps the hands about them and applies overpressure to achieve maximum stress. The knees are then released and the feet placed back on the couch. The sequence is repeated about ten times. The first two or three flexion stresses are applied cautiously, but when the procedure is found to be safe the remaining pressures may become successively stronger, the last two or three being applied to the maximum possible.
Fig. Flexion in lying.
Flexion in lying causes a stretching of the posterior wall of the annulus, the posterior longitudinal ligament, the capsules of the facet joints, and other soft tissues. As the movement takes place from below upwards the lower lumbar and lumbo-sacral joints are placed on full stretch at the beginning of the exercise as soon as movement is initiated. Thus, the procedure is very important in flexion dysfunction when shortening of posterior soft tissues has occurred.
The procedure should always be performed following stabilisation of a reduced posterior derangement. This ensures that no flexion loss remains after the patient has become symptom free. By keeping the patient in extension and avoiding flexion as healing takes place, we permit scar formation with the joints in a shortened position. This shortened position will be held by the scar as it contracts, the patient remaining painfree but unable to flex. Any attempts to perform flexion beyond the limits imposed by the contracting scar, will produce pain. Therefore, further flexion will be avoided and adaptive shortening gradually worsens.
Flexion in lying performed regularly following reduction of posterior derangement allows the formation of an extensible scar in the midst of an elastic structure. Should we permit an inextensible scar to remain in the midst of an elastic structure, — the disc in this case — then sooner or later the patient will inadvertently move beyond the limitations of the scar, which results in further tearing of soft tissues and apparent recurrence of the derangement condition. This basic complication of healing exists throughout the muscular as well as the articular systems.
Flexion in lying also causes a posterior movement of the fluid nucleus and will be utilised in anterior derangement situations (Derangement seven) to reverse the excessive anterior position of the nucleus.