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Regenerative Medicine

Regenerative Therapy Offers a Safe Alternative to Piriformis Injections

Medically Reviewed by Cellaxys

By Published: August 28, 2019Updated: June 11, 2023No Comments

The piriformis is a muscle in the hip region that can become a source of pain for some individuals.

As the underlying causes become worse and the issue is aggravated, pain in the piriformis can become debilitating. Doctors will often recommend conventional treatment options which may be ineffective depending on the severity of pain.

Though steroid injections are often the most popular of these alternative treatment methods, they often have negative consequences. Regenerative therapy offers a solution to not only the pain experienced by an individual with piriformis complications but the underlying causes of that pain as well.

Anatomy of Piriformis

The piriformis is a small muscle located deep within the buttocks region. It is one of 6 muscles located behind the gluteus maximus (major outer muscle of the buttocks) which are known as the lateral rotator group. This group of muscles is responsible for rotating the femur in the hip joint. An individual can feel this muscle if they stand on a single leg and twist their body to one side.

The piriformis, along with the other 5 muscles in the lateral rotator group, originates in the hip bone and attaches to the upper portion of the femur. Specifically, the piriformis originates from the sacrum, the portion of the spine in the gluteal region, and exits the pelvis through a small hole known as the greater sciatic foramen to connect to the upper portion of the femur.

The muscle fills the upper portion of the hole in the pelvis and inserts into the femur by a rounded tendon, often blending with other tendons in the region.

The piriformis is innervated by the sacral plexus. The sacral plexus is a branching network of intersecting nerves that provides motor and sensory nerves throughout the posterior thigh. Along with the host of disorders and issues which may arise in the piriformis itself, the sacral plexus may also become a source of pain due to trauma, nerve compression, vascular disease, or infection.

The piriformis serves an important role in the lower body as it helps to stabilize the hip joint as well as lifts and rotates the thigh away from the body. This allows an individual to be able to walk, shift their weight from one leg to the other, and maintain balance. Injury to this vital muscle can cause instability and can be a source of constant pain if left unchecked.

Types of Piriformis Injuries

The piriformis is a common source of pain in the buttocks and posterior leg. Pain in the piriformis can begin spontaneously or after an injury. When the piriformis becomes damaged and is aggravated, the muscle goes into spasms. These spasms squeeze and irritate the nerves of the sacral plexus and create pain throughout the piriformis.

Patients who are diagnosed with lower back pain may be experiencing some type of piriformis issue. A delay in diagnosing piriformis pain can lead to untreatable damage to the nerves within it. Compensatory changes to the biomechanics in the hip and thigh due to piriformis injury can lead to pain, paresthesia, hyperesthesia, and muscle weakness.

Some common causes of piriformis pain or injury are:

  • Inflammation
    • Jobs that require constant sitting and standing, especially with an extra load on the body, may irritate the piriformis and cause the muscle to “puff up”, compressing the nerves within.
  • Trauma
    • Blunt trauma to the buttocks from a sports injury, fall, or other accidents, can cause microtears in the piriformis and lead to undue stress to the nerves within.

Other, less common, inciting events for piriformis pain are:

  • Hematoma
  • Scar formation
  • Cysts
  • Tumors

Regardless of the event that led to piriformis pain, the mechanics are all the same. Once the piriformis is injured in any way, the nerves within the piriformis become aggravated or compressed and cause an individual to feel painful spasms in the buttocks region.

Signs and Symptoms of Piriformis Injury

Several signs and symptoms can help an individual conclude whether or not there may be damage to the piriformis. Some of the most common symptoms of piriformis injury are:

  • Pain with sitting, standing, or lying longer than 15 to 20 minutes
  • The pain improves with mobilization and worsens with no movement
  • Pain when rising from a seated or squatting position
  • Change of position does not relieve pain completely
  • Difficulty walking or maintaining balance
  • Foot numbness
  • Headache
  • Neck pain
  • Abdominal, pelvic, and inguinal pain
  • Pain with bowel movements

Beyond these symptoms an individual can also watch out for signs such as the following:

  • Tenderness over the piriformis muscle
  • Palpable mass in the buttock
  • Traction of affected limb provides moderate relief of pain
  • Asymmetrical weakness in the affected limb
  • Limited range of motion in the lower extremities

Though signs and symptoms vary from person to person, if an individual is experiencing any of the above, there may be a deeper issue relating to the piriformis muscle which will require doctor intervention. Due to the location of the piriformis, oftentimes, steroid injections are the only solution.

History of Piriformis Injections

The application of steroids to treat certain types of pain was first discovered in 1929 by a team of chemists working at the Mayo clinic. The team discovered that injecting certain steroids could give short-term pain relief and reduce swelling from inflammation of the joints, tendons, or bursa found throughout the body. 

Since their discovery, steroid injections have been used to treat several ailments and have been administered intravenously, orally, and intra-articularly (into a joint), or transdermally (using patches that lay directly on the skin).

Composition and Mechanics of Piriformis Injections

There are a variety of steroids that can be used to treat different conditions, but problems with soft tissues such as the piriformis typically involve the use of corticosteroids specifically. Corticosteroids are synthetic drugs that resemble cortisol, a hormone that the body naturally produces. Steroid injections work by suppressing the immune system, thus reducing inflammation, pain, and swelling at the site of injection. Risks exist, in particular in the long-term use of steroids.

The body’s natural response to injury is to create a sort of shelter in that area. By pushing fluid to the site of an injury, the body tries to protect that area from further trauma. Though swelling is intended to defend the body, too much of it can cause severe pain. 

This is the case in piriformis injuries. The body responds to trauma in the piriformis by pushing fluid to the area causing it to swell. The swelling then compresses the nerves within the piriformis causing a pain response. By injecting cortisone steroids into the piriformis, the compression around these nerves is reduced and the pain is minimized.

Application of Piriformis Injections

Application of Piriformis Injections

Piriformis injections are a simple outpatient procedure. A typical piriformis injection will begin with the doctor having the patient lay on their side with their knees bent towards their chest. The doctor will examine the patient by pushing various portions of their buttocks to find the spot or trigger points that are the most painful. These sites are typically where the muscles and nerves are most inflamed or tight.

After the source is found, a doctor will place an electrode on the portion of the buttocks which induced the largest pain response. The electrode is connected to an electronic nerve stimulator and a second wire is connected to a special insulated needle. The affected area is then cleaned with an antiseptic solution and numbed with a local anesthetic.

The doctor will insert the insulated needle into the piriformis muscle and allow a small electrical current to pass through this needle into the muscle. The needle will cause a mild contraction of the muscle which will help the doctor more precisely locate the area which is causing the pain. Finally, the doctor will inject the steroid and local anesthetic into the piriformis and allow it to take hold within the muscle.

Most injections will take 3 to 7 days before providing relief. Additionally, the injection may cause a bit of swelling in the first few days after its application. These injections are typically followed by a routine to stretch and exercise the piriformis. Some individuals may also need follow-up appointments after the initial injection to examine the pace of recovery or to administer further injections.

Risks from Piriformis Injections

Steroid injections have been shown to produce an anti-inflammatory response in the body. This response reduces the compression of nerves in the piriformis thereby reducing the pain an individual experiences. Although evidence for the efficacy of steroids in cases of chronic musculoskeletal pain is inconclusive, steroid injections have proven helpful in the treatment of carefully selected patients.

Though steroid injections are a viable option for piriformis pain management, these treatments run several risks. The most common complications with piriformis injections are:

  • Joint infection
  • Nerve damage
  • A temporary flare of pain and inflammation in the joint
  • Tendon weakening or rupture
  • Thinning of skin and soft tissue around the injection site
  • Thinning of nearby bone (osteoporosis)
  • Death of nearby bone (osteonecrosis)
  • Whitening or lightening of the skin around the injection site

Of these risks, nerve damage and muscle, bone, and soft tissue degradation are the most common.

Nerve Damage

If complications in steroid injections do occur, nerve damage is highly likely. Nerve injury can typically be felt immediately at the time of injection. If a nerve is damaged during the procedure, a patient will feel a shooting pain along with sensory distortion, motor weakness, and muscle atrophy. 

Appropriate needle positioning is vital to avoid nerve complications during a piriformis injection. Once nerve damage is present, surgical exploration is often the only way to manage the issue.

Muscle, Bone, and Soft Tissue Degradation

Prolonged use of steroids can weaken the injection site’s muscle, bone, and soft tissue foundations. Tissue problems experienced after steroid injections typically develop as a slowly progressive, painless weakness. 

Over time, these weaknesses become more apparent and eventually can become immobilizing. Although these problems arise most commonly near the injection site, steroids may leak out to other parts of the body and lead to damage elsewhere.

Conventional Treatment Options for Piriformis Pain

Though steroid injections are a common choice for patients seeking relief from piriformis pain, doctors will typically recommend that a patient attempts conventional treatment beforehand. These conventional treatment options include:

  • Nonsteroidal anti-inflammatory drugs
  • Muscle relaxants
  • Physical therapy
  • Surgery

Nonsteroidal Anti-Inflammatory Drugs

Over-the-counter anti-inflammatory drugs such as acetaminophen have been considered the medications of choice in the management of the many conditions that manifest as low back pain, including piriformis syndrome. 

Muscle Relaxants

Muscle relaxants are another typical piriformis syndrome therapy. Medications like cyclobenzaprine and other muscle relaxants are used to treat all sorts of lower back discomfort, including piriformis syndrome, which is caused by inflammation and spasm.

Adverse consequences with low dosages or sporadic uses of muscle relaxants are minimal. Dryness of mouth, drowsiness, and dizziness are common with these low dosages. High dosages and prolonged use of muscle relaxants may have worse consequences including muscle degradation and addiction.

Physical Therapy

Though physical therapy may not affect acute piriformis pain, it may provide relief to those with mild discomfort. Typically, physical therapy will require several sessions with a therapist as well as an exercise regimen outside of the therapy sessions. By increasing the muscle mass in the anterior muscles of the piriformis, physical therapy can help reduce the load the piriformis has to endure throughout the day.


Highly invasive, time-consuming, and expensive, surgery is thought to be the last resort for many complications with muscles such as the piriformis. The location of the deeply nested piriformis makes surgery difficult and increases the risks inherent to surgery. Along with the surgery itself, a patient may have to apply the above-listed conventional treatment methods post-surgery to help the recovery process.

Regenerative Therapies for Piriformis Pain

Though regenerative therapies have been around for the last half-century, recent advancements have produced another viable treatment option for piriformis pain. The two most common methods applied in regenerative therapy are platelet-rich plasma (PRP) and cell-based therapies.

The processes are typically simple outpatient procedures and use the patient’s own blood or “autologous” tissues as the source material, ensuring that the patient’s body won’t reject the treatment.

  • PRP Therapy. It is the process of extracting a patient’s blood platelets, processing them, and then reinjecting them into the source of pain, i.e., the piriformis. The platelets are the body’s natural defense against injury and contain several growth factors used to amplify the body’s own healing factors. Once injected, the platelets attach to the injury site and produce chemical signals to draw the body’s healing factors towards it. They also produce a web-like sticky structure called fibrin that supports the growth of tissue development. PRP is completed within 45 minutes. 
  • Cell-Based Therapies. Also known as stem cell therapy, cell-based therapies use the patient’s own cells to boost the body’s own healing processes. It involves harvesting healthy cells from the patient’s adipose (fat) tissue, called Minimally Manipulated Adipose Tissue (MMAT) transplant, and bone marrow, called Bone Marrow Concentrate (BMAC). These cells are then re-injected into the patient’s injury site for a speedy recovery. MMAT and BMAC are performed in 1.5 to 2 hours.

These techniques are often used in unison with MRI technology to place the injection into the site of piriformis pain accurately. After the injection, patients typically experience a brief period of swelling, which goes away within a few days. 

Once the swelling has subsided, these treatments keep working, creating an atmosphere suitable for repair and providing the area with the building blocks it needs to regenerate the damaged tissue. 

While cell-based and PRP therapies can be used alone, they are typically applied in unison to amplify the healing effect. Patients can typically expect results to last anywhere from 6 months to a year from a single treatment.

Dr. Pouya Mohajer

Director of Regenerative Interventional Spine Medicine
Board certification in Anesthesiology and Interventional Pain Medicine
Fellowship-trained from Harvard University
UCLA Alumni


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