The piriformis is a small muscle which runs from the back of your pelvis to the top of your thigh bone (femur) and is deep to the gluteal muscles. It is responsible for rotating the leg outward and stabilizes the hip joint enabling us to walk, shift our weight from one leg to another and balance on one foot. These are major components of running as you are constantly shifting your weight back and forth between feet while always having one foot off the ground.
The piriformis can get injured in runners specifically because of the repetitive stress placed on the muscle as it works to shift the body weight back and forth. In overuse injuries to the piriformis, the muscle is forced to work beyond its capability without being given the proper amount of time to recover. The muscle then responds by tightening up, increasing the tension between the muscle and the tendon connecting the muscle to the hip bone.
What is piriformis syndrome?
Piriformis syndrome is a neuromuscular disorder that occurs when the piriformis muscle compresses the sciatic nerve. The sciatic nerve is a thick, long nerve that passes alongside the piriformis muscle and travels down the back of the leg, branching off into smaller nerves throughout the leg and into the foot. However, in as much as 22% of the population, the sciatic nerve either pierces or splits the piriformis muscle, predisposing these individuals to piriformis syndrome.
In piriformis syndrome, trauma to, spasm or repetitive contraction of the piriformis muscle compresses the sciatic nerve causing pain, numbness, or tingling of the buttock and leg. It may present as pain directly in the center of the buttocks that can be elicited with direct compression over the piriformis muscle, as a tight muscle can become sore due to decreased blood flow to the area. Piriformis syndrome can also present with pain that travels down the back of the leg into different portions of the lower leg. The pain travels down the sciatic nerve and can progress along any of the branches of this nerve.
Piriformis syndrome may also present as pain in and around the outer hip bone, as the increased tension of the muscle can create a bursitis. Bursitis is an inflammation of the bursa, or fluid filled sac that cushions a joint to help reduce the friction caused by movement. The increased tension of the piriformis can place an added stress on the hip joint, causing this inflammation of the bursa.
The most common complaint of individuals with piriformis syndrome is pain with sitting greater than 15-20 minutes. Other symptoms include pain starting in the gluteal area that radiates down the back of the thigh usually stopping above the knee, pain that improves with walking and is worsened by no movement, pain when rising from seated or squatting position, numbness in the foot and weakness throughout the leg.
Causes of piriformis syndrome
Piriformis syndrome may be primary or secondary. Primary piriformis syndrome has an anatomic cause, such as those individuals who present with a split piriformis or split sciatic nerve as the nerve passes through the piriformis muscle.
Secondary piriformis syndrome is more common however and is characterized as a macrotrauma (such as falling on the buttocks causing soft tissue inflammation or spasm with resulting nerve compression) or a microtrauma as a result of overuse of the muscle (such as in long distance running or prolonged sitting). Often overuse injuries occur because of weakness of the surrounding muscles. This is common in piriformis syndrome, as the piriformis has to work extra to stabilize the joint because it must compensate for weakness throughout the hip.
Piriformis syndrome is more common in women than men, possibly because women tend to have a wider Q angle, which is the angle between the hip and knee as women tend to have a wider pelvis creating a greater angle at the knee.
Treatment
Patient education is always the first step in treating any injury. Any position that compresses the sciatic nerve and triggers pain should be avoided. For runners, running on flat, even surfaces is advised, avoiding running on uneven terrain or hills that will create extra work for the piriformis in stabilizing the hips. Ice is an excellent way to fight the inflammation at the piriformis. It should be used for 15-20 minutes at a time and can aid in pain relief. Heat may also help to relieve symptoms, as it encourages blood flow to the injured muscle for more rapid healing, as muscle tightness restricts normal blood flow.
Another was to promote blood flow and ultimately muscle healing is through manual therapy. Manual therapy techniques such as myofascial release (MFR) can be applied to help relieve the tissue tension and trigger points that can form in the piriformis and surrounding muscles. Trigger points are small knots that develop in a muscle when it becomes injured or overworked. These areas are highly irritable and sensitive to pain when pressure is applied and can often send referred pain to other areas. MFR can help decrease the pain caused by trigger points and should be used in combination with exercise.
Once the pain is more manageable, piriformis stretching and hip strengthening should be introduced. Stretching of the piriformis muscle will help to decrease the tissue tension of the muscle while also deceasing the stress the piriformis is placing on the hip joint. It is also crucial to strengthen the surrounding hip muscles in order to relieve some of the stress that is placed on the piriformis. If the hip is strong overall, the piriformis will not have to work as hard to control movements at the joint.
Nerve glides are also a technique that help to reduce the symptoms of piriformis syndrome as they travel down the sciatic nerve. The concept behind nerve gliding is to place a stretch on the sciatic nerve, just as you would stretch a muscle, in order to decrease the neural tension caused by the piriformis muscle. This allows for increased signal conduction from the nerve to the muscle. These glides may reproduce some of the leg symptoms initially, but the goal is to desensitize the nerve to allow for increased movement without symptoms.
Differential Diagnosis
It is important to note that piriformis syndrome may present very similarly to other conditions, particularly of the low back. The sciatic nerve originates from the lumbar spine and can not only be compressed by the piriformis muscle, but can also be impinged when the discs separating the bones of the spine herniate or bulge outward, pressing on the nerve. The spine can also be compressed by conditions such as degenerative disc disease, compression fracture of the vertebrae, and spinal stenosis, which is a narrowing of the spinal canal which the spinal cord travels through. It is very crucial to have both the back and hip thoroughly inspected to rule out any other possible causes of sciatic nerve pain. If you are experiencing any of the symptoms described above, contact Total Performance Physical Therapy to schedule an appointment.
