What is Quadrilateral Space Syndrome (QSS)?

Quadrilateral Space Syndrome (QSS) is a rare condition that occurs when the axillary nerve and/or the posterior circumflex humeral artery get squeezed or compressed as they pass through a small area in the back of your shoulder called the 'quadrilateral space.' This compression can lead to pain, numbness, tingling, and weakness in your arm.

QSS is often caused by repetitive overhead activities, common in athletes like throwers, swimmers, and tennis players. It can also result from repeated motions that narrow the space (overuse), extra bands of tissue that can form and compress the nerve or artery (fibrous bands), trauma or injury such as a shoulder dislocation or a direct blow to the shoulder which can cause swelling or scar tissue, or muscle enlargement if muscles in the area grow significantly (e.g., in bodybuilders), they can crowd the space.

What are the common symptoms of QSS?

Symptoms typically include vague pain or a dull ache in the back of the shoulder, sometimes radiating down the arm; numbness, tingling, or a 'pins and needles' sensation in the shoulder and upper arm; pain that worsens with overhead movements or when your arm is in a 'throwing' position; tenderness when pressure is applied over the back of the shoulder in the quadrilateral space; weakness or fatigue in the arm, especially when lifting or rotating it; and sometimes, shrinking (atrophy) of certain shoulder muscles like the teres minor or deltoid.

How is QSS diagnosed?

Diagnosing QSS can be challenging because its symptoms can be similar to other shoulder problems. Your doctor will ask about your symptoms, activities, and any past injuries; perform a physical examination to check your shoulder's range of motion, strength, sensation, and tenderness; may order imaging tests like MRI or ultrasound to look at the quadrilateral space, assess muscle size, and check for any abnormalities or scarring. In some cases, nerve conduction studies (NCS) or electromyography (EMG) might be performed to evaluate how well the axillary nerve is working. An injection of local anesthetic into the quadrilateral space that temporarily relieves your symptoms can also help confirm the diagnosis.

What are the non-surgical treatment options?

Most cases of QSS improve with non-surgical treatment. These options focus on reducing pressure on the nerve and artery, managing pain, and restoring function: rest and activity modification (avoiding or modifying activities that worsen your symptoms, especially overhead movements); anti-inflammatory medications (over-the-counter or prescription NSAIDs like ibuprofen can help reduce pain and inflammation); ice or heat packs (applying ice can help reduce pain and inflammation, especially after activity, heat can help relax muscles); physical therapy (a physical therapist will guide you through exercises to maintain or improve shoulder range of motion and flexibility, strengthen the muscles around your shoulder to provide better support, improve posture and body mechanics); and corticosteroid injections (in some cases, your doctor may suggest an injection of corticosteroid medication into the area to reduce inflammation and pain).

When is surgery considered for QSS?

Surgery is usually considered if non-surgical treatments haven't significantly improved your symptoms after about six weeks or more; symptoms are severe or progressively worsening; or there's clear evidence of nerve damage or significant compression.

What does the surgical procedure involve?

The goal of surgery, called decompression, is to relieve pressure on the axillary nerve and posterior circumflex humeral artery. This typically involves making a small incision at the back of your shoulder; identifying the compressed nerve and artery; carefully removing or cutting any fibrous bands, scar tissue, or other abnormal structures that are causing the compression. The procedure is designed to free up the nerve and artery, allowing them to function normally.

What are the potential risks of surgery?

As with any surgery, there are potential risks, though QSS surgery is generally safe. These can include infection, bleeding, damage to surrounding nerves or blood vessels, scarring, persistent pain or incomplete relief of symptoms, and reaction to anesthesia. Your surgeon will discuss these risks with you in detail.

What do I need to do before surgery?

Your healthcare team will provide specific instructions, but generally, you may need to undergo a pre-operative physical examination and blood tests; stop certain medications (e.g., blood thinners, some anti-inflammatory drugs) a week or two before surgery; arrange for someone to drive you home after surgery and help you during the first few days of recovery; and avoid eating or drinking for a certain period before the surgery.

What can I expect immediately after surgery?

You will likely have your arm in a sling to help it rest and heal. You may experience some pain, which will be managed with medication. Your surgical site will be covered with a dressing. Your surgeon will give you instructions on wound care and activity restrictions.

How long is the typical recovery period?

Recovery times vary for each person, depending on the severity of the condition and how long the nerve was compressed. First few weeks (0-2 weeks): Focus on rest, pain management, and protecting the surgical site. Gentle elbow and wrist movements will be encouraged. Weeks 2-6: You will start physical therapy, focusing on gentle range-of-motion exercises for your shoulder. After 6 weeks: As healing progresses, your physical therapist will introduce strengthening exercises to rebuild muscle strength. Overall, it can take several weeks to months to feel significant improvement, as nerve healing is a slow process.

What does rehabilitation/physical therapy involve?

Physical therapy is crucial for a successful recovery. Your therapist will design a personalized program that may include pain and swelling management (using ice, gentle massage, or other techniques); range of motion exercises (to restore full movement in your shoulder); strengthening exercises (targeting the muscles around your shoulder, including the deltoid and teres minor, which may have been weakened); postural correction (to improve overall shoulder mechanics); and activity-specific training (gradually reintroducing movements related to your work, sports, or daily activities).

How will pain be managed?

Your doctor will prescribe pain medication to help manage discomfort after surgery. This may include prescription pain relievers (e.g., opioids for a short period); over-the-counter pain relievers (e.g., acetaminophen, ibuprofen) as recommended by your doctor. You may also use ice packs to reduce localized pain and swelling.

When can I expect to return to daily activities, work, driving, and sports?

This timeline varies greatly based on your recovery progress and the demands of your activities. Daily activities: Light daily activities can usually be resumed within a few days to weeks. Driving: You can typically drive once you are no longer taking strong pain medications and have sufficient control and range of motion in your shoulder to safely operate a vehicle (often a few weeks after surgery). Work: Return to work depends on the nature of your job. Light, desk-based work might be possible within a few weeks, while jobs requiring heavy lifting or repetitive overhead movements will take longer, potentially several months. Sports: A gradual return to sports, especially overhead activities, will be guided by your physical therapist and surgeon, often not for several months after surgery. Full return to competitive sports may take 3-6 months or longer.

What is the expected long-term outcome?

For many patients, surgical decompression of QSS provides significant relief from pain, numbness, and weakness, allowing them to return to their normal activities, including sports. Nerve healing can be slow, so improvement may continue for several months. While some mild symptoms may occasionally linger, the goal is to significantly improve your quality of life and shoulder function.

Non-Surgical Shoulder Treatment Options

Ultrasound Therapy for Shoulder Pain

Get Clear, Concise Answers to Your Top Questions About Ultrasound Therapy for Shoulder Pain

Ultrasound therapy is a common non-surgical treatment option used in physical therapy to relieve shoulder pain, reduce inflammation, and promote the healing of injured soft tissues. This Q&A guide covers how ultrasound therapy works, what conditions it treats, what to expect during a session, and how it fits into your overall shoulder recovery plan.

Q1. What is ultrasound therapy for shoulder pain?

Therapeutic ultrasound is a non-surgical treatment method used by physical therapists and sports medicine specialists. It uses high-frequency sound waves to treat deep tissues inside your shoulder, helping to ease pain, reduce muscle spasms, and speed up the healing of soft tissue injuries like tendinitis or bursitis.

Q2. How does ultrasound therapy work to treat shoulder pain?

Ultrasound therapy works in two main ways to help your shoulder heal:

Thermal Effects (Deep Heating): The sound waves create gentle vibrations deep within the muscles, tendons, and ligaments of your shoulder. This generates mild heat, which increases blood flow, relaxes tight muscles, and reduces stiffness.
Mechanical Effects (Cellular Healing): The sound waves cause microscopic bubbles to form and expand in the tissues, a process called cavitation. This stimulates cells to repair themselves, reduces inflammation, and promotes the healing of injured soft tissues.

Q3. What shoulder conditions can be treated with ultrasound therapy?

Your healthcare provider or physical therapist may recommend ultrasound therapy for several common shoulder issues, including:

Rotator cuff tendinitis or tendinopathy
Shoulder bursitis (inflammation of the fluid-filled sac in the shoulder)
Adhesive capsulitis (frozen shoulder)
Calcific tendinitis (calcium deposits in the rotator cuff tendons)
Muscle strains, ligament sprains, or joint stiffness

Q4. What is the difference between diagnostic ultrasound and therapeutic ultrasound?

While both technologies use sound waves, they serve very different purposes:

Diagnostic Ultrasound: This is used to take pictures of the inside of your shoulder. It helps doctors see structures like the rotator cuff tendons to diagnose tears or inflammation.
Therapeutic Ultrasound: This does not create any images. Instead, it uses different sound wave frequencies to deliver energy deep into the shoulder tissues to relieve pain and promote healing.

Q5. What does the ultrasound therapy procedure feel like?

The treatment is generally painless and comfortable. Your therapist will apply a cold gel to your shoulder skin and move a small, handheld device called a transducer in gentle circular motions. You might feel a mild, pleasant warming sensation or a slight tingling, but you should not feel any pain. If you feel any hot spots or discomfort, let your therapist know right away.

Q6. How long does a typical ultrasound therapy session last?

An ultrasound therapy session is quite brief. The active treatment usually lasts between 5 and 10 minutes per area. Because the therapy is highly targeted, it is typically performed as part of a longer physical therapy appointment that includes exercises, stretching, or other hands-on treatments.

Q7. How many sessions of ultrasound therapy will I need to see results?

The number of sessions depends on your specific shoulder condition and how quickly your body responds. Many patients begin to notice improvements in pain and mobility after 3 to 6 sessions. A typical treatment plan may involve sessions 2 to 3 times a week for a few weeks, which is continuously adjusted based on your progress.

Q8. Are there any side effects or risks associated with ultrasound therapy?

When performed by a trained professional, therapeutic ultrasound is very safe and has minimal risks. The most common side effect is mild skin redness from the gel or the transducer's movement. Rare risks include minor burns if the transducer is held in one spot for too long, which is why therapists keep the device moving constantly.

Q9. Who is a good candidate for shoulder ultrasound therapy?

You may be a good candidate for ultrasound therapy if you have persistent shoulder pain from a soft tissue injury, joint stiffness, or chronic inflammation, and you have not found relief from rest or ice alone. It is especially helpful for individuals who want to avoid surgery or are looking for drug-free pain relief options.

Q10. Who should avoid ultrasound therapy (contraindications)?

While therapeutic ultrasound is safe for most people, it should not be used on patients who have certain medical conditions. Contraindications include:

A cardiac pacemaker or other implanted electronic device near the shoulder
Active infections, open wounds, or vascular diseases in the shoulder area
A history of cancer or tumors in the treatment area
Impaired sensation (numbness) in the shoulder, which makes it hard to feel if the skin gets too warm
Pregnancy (it should not be used near the abdomen or lower back, and caution is used elsewhere)

Q11. Is ultrasound therapy used alone or combined with other treatments?

Ultrasound therapy is rarely used as a standalone treatment. It is most effective when integrated into a comprehensive rehabilitation program. Your physical therapist will likely combine ultrasound with stretching, strengthening exercises, manual therapy, and advice on activity modification to address the root cause of your shoulder pain.

Q12. How should I prepare for my shoulder ultrasound therapy session?

No special preparation is required. It is best to wear loose, comfortable clothing that allows easy access to your shoulder, such as a tank top or loose-fitting t-shirt. Ensure the skin on your shoulder is clean and free of lotions, creams, or oils before your appointment.

Q13. What should I expect during recovery and immediately after a session?

There is no recovery time needed after ultrasound therapy. You can return to your normal daily activities immediately after your session. Some patients feel a temporary reduction in pain and improved movement right away, while others experience gradual improvement over the course of their full treatment plan.

Q14. Does insurance cover ultrasound therapy for shoulder pain?

In Ontario, therapeutic ultrasound is usually covered under private health insurance or extended health benefits when it is part of a physical therapy program. While OHIP (provincial health insurance) does not cover private physiotherapy for most adults, public clinics or programs may cover it for eligible seniors, youth, or post-hospitalization patients.

Q15. How effective is ultrasound therapy compared to other non-surgical treatments?

Ultrasound therapy is a valuable, non-invasive tool for reducing acute pain and muscle spasms, but it is generally considered supportive rather than curative on its own. For long-term recovery and preventing recurrence, active treatments like guided exercise and physical therapy are crucial. Your healthcare team will help determine the best combination of treatments for your recovery.

We encourage you to write down any specific questions you have and discuss them thoroughly with your surgeon, doctor, or physical therapist. They are your best resource for personalized advice and care.

Disclaimer: This brochure provides general information and is not a substitute for professional medical advice. Always consult your doctor or qualified healthcare provider with any questions you may have regarding your specific medical condition and treatment plan.

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