Anatomy
The piriformis muscle is a small muscle that originates from the sacrum, runs across the sacrum and attaches to the greater trochanter of the femur. The muscle helps stabilise the pelvis and rotates the thigh outwards. The piriformis is in close contact with the sciatic nerve (n ischiadicus).
M. Piriformis:
A. Trochanter major
B. Trochanter minor
C. Femur
D. M. obturatorius externus
E. Tuber ischiadicum
F. M. obturatorius internus
G. Lig. sacrotuberale
H. Lig. sacrospinale et. m coccygeus
I. M. piriformis
Cause of the problem
If the muscle is overloaded, it will become tense and sore. This can be due to poor pelvic stability, significant leg length discrepancy or direct trauma (kicks, punches), but the causes of piriformis muscle irritation are not well established.
In some cases, the muscle can become so tense and tight that it pinches the sciatic nerve. There is disagreement about the certainty of the diagnosis (Sharma S, et al. 2023)
Symptoms
Pain deep in the buttocks and often in the lower back, possibly with periodic radiating to the leg. There may be pain and sensory disturbances down the leg if there is irritation of the sciatic nerve. The pain is often provoked by sitting, running and jumping.
Examination
The diagnosis is usually made by clinical examination alone, where there is tenderness when the muscle is pressed (deep in the buttock), stretched (knee to opposite shoulder) and activated. In the straight leg raise test, piriformis syndrome, unlike disc herniation, is relieved if the leg is externally rotated and no worsening if the foot is bent backwards (dorsiflexion) (Bragard’s test).
There are no suitable methods to confirm the diagnosis by imaging.
Treatment
Treatment usually consists of relief from pain-inducing activity, stretching and subsequent graduated strength training of the muscles around the lower back and buttocks within the pain threshold.
If the pain is bothersome and does not improve with exercise, medical treatment may be considered in the form of arthritis pills (NSAIDs) or injection of adrenal cortex hormone into the maximum tender point in the muscle. Only in very rare cases of nerve entrapment may surgery be indicated.
Complications
If the progress is not smooth, you should consider whether the diagnosis is correct or if there are complications.
In particular, the following should be considered:
