4 Letters to the editor The piriformis syndrome To the Editor: May I congratulate Dr. Tom Maxwell on his excellent article on the involvement of the piriformis muscle in the sciatic syndrome. You might be interested in my experience with the piriformis in these cases and some conclusions that I have drawn. I first learned about the muscle involvement from Dr. R. B. Richter in 1938 when I was a student. He was a Bone Setter turned Chiropractor and lectured and demonstrated muscle adjusting. It has been my conclusion from treating a large number of cases over the years that the muscle is involved either primarily where there is history of a fall or trauma and the muscle has been sprained at its attachment on the trochanter, or that it is a reflex spasm in the muscle associated with the antalgic posture caused by a disc her- niation or bulge or a nerve root irritation in the lower lum- bar spine. In the case of the piriformis sprain, that is, where it is in- volved primarily and is the cause of the sciatic radiation one can do cross fiber manipulation or goading with ex- cellent results and immediate relief from sciatica. But where the piriformis if reflexly or secondarily in- volved it has been my experience, that to work heavily over this muscle whether it be near the sciatic nerve or as far away as possible, will increase the sciatic pain. Therefore I do only light manipulation near the tendinous attachment or in the severe cases I don't manipulate the muscle at all. Trusting that these comments may add something to Dr. Maxwell's fine article. Herbert K. Lee, DC Toronto, Ontario The Helfet Test To the Editor: I am presently researching material in preparation for a paper on the "patello-femoral pain syndrome" and I have discovered a little-known orthopedic test that can be con- verted into an excellent motion palpation test for the knee joint. As reported by many authors, there normally occurs an involuntary rotation of the tibia on the femur, which oc- curs during flexion and extension of the knee. A maximal rotation of 60 of lateral rotation occurs during the last 100 of extension and the reverse during the first 100 of flexion. This has been called the "screw-home mechanism". Helfet has designed a simple test to determine the in- tegrity of the knee joint relative to the presence of this nor- mal motion. It was designed to detect the presence of an intra-articular "loose-body" which he found disturbed the normal biomechanics of the joint. Quite simply, a dot is placed marking the location of the tibial tubercle; with the knee flexed (see Figure 1). A se- cond dot is placed in the center of the patella. The knee is then passively extended and the motion of the dot relative to the patella, is observed. A positive Helfet test occurs when there is lack of full lateral movement of the dot. I have found that palpating the tibial tubercle during this passive test allows for more subtle determination of disturbed mechanics of the joint. It is conceivable that aside from intra-articular bodies, both a lack of rotational joint play at the tibio-femoral articulation, and imbalance in the tonicity of the internal and external rotators of the tibia could promote the pathomechanics observed by this test. Interestingly, all but two of these muscles find their origin in the pelvis. Figure 1: The normal Helfet test (see text for description). Howard Vernon, DC Senior Clinical Resident CMCC THE JOURNAL OF THE CCA - DECEMBER, 1978 127