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-Operative Exercises

Passive and Active-Assisted Range of Motion (AAROM) Exercises

Step-by-step home exercise guide for Passive and Active-Assisted Range of Motion (AAROM) to improve mobility, strength, and recovery.

Active rehabilitation is a cornerstone of recovery. On this page, we outline key home exercises for Passive and Active-Assisted Range of Motion (AAROM) designed to help you regain shoulder function. Always consult your care team before beginning.

Passive and Active-Assisted Range of Motion (AAROM) exercises are crucial first steps in shoulder rehabilitation. These exercises help restore mobility, prevent joint stiffness, and improve blood circulation without overloading healing tissues. By using external aids such as wands, pulleys, and wall slides, you can safely guide your shoulder through its natural movement patterns while staying strictly within a tolerable pain threshold.

General Guidelines & Safety Precautions

The Pain Threshold Rule: Never force the movement. Perform all exercises within a tolerable pain limit—aim for a mild stretch or gentle tension, never sharp or stabbing pain.
Warm-up: If allowed by your doctor, apply a warm pack to your shoulder for 10-15 minutes before starting to relax the muscles.
Controlled Movements: Perform each repetition slowly and smoothly. Avoid jerky or sudden motions.
Posture: Keep your chest lifted and shoulders relaxed (do not shrug your shoulders up toward your ears).

Exercise 1: Wand/Cane Forward Flexion

Purpose: To safely increase the forward elevation of your arm using your healthy arm to assist.

Equipment Needed: A lightweight wand, cane, broomstick, or PVC pipe.

Starting Position: Lie flat on your back on a firm bed or mat. This position supports your spine and isolates the shoulder joint.

Instructions:

Hold the wand with both hands, shoulder-width apart, palms facing down.
Using your unaffected arm to push and guide the wand, slowly raise both arms straight up toward the ceiling.
Continue to guide the arms overhead as far as comfortable without exceeding your pain threshold.
Hold the stretch at the top for 5 to 10 seconds.
Slowly lower the wand back down to the starting position using your unaffected arm for control.

Dosage: Perform 10 to 15 repetitions, 1 to 2 times per day.

Tips/Common Mistakes: Do not arch your lower back to get more range. Keep your elbows as straight as comfortable.

Exercise 2: Wand External Rotation

Purpose: To gently restore outward rotation of the shoulder joint, which is vital for daily activities like reaching or grooming.

Equipment Needed: A wand, cane, or broomstick.

Starting Position: Lie flat on your back. Keep your elbows bent at 90 degrees and tucked close to your sides.

Instructions:

Hold the wand with both hands, palms facing up.
Keep the elbow of your affected arm tucked against your side (you can place a rolled towel under the elbow to help keep it in place).
Using your unaffected arm, push the wand horizontally across your body toward your affected side, rotating the affected arm outward.
Hold the stretch at the end range for 5 to 10 seconds.
Slowly return to the starting position.

Dosage: Perform 10 to 15 repetitions, 1 to 2 times per day.

Tips/Common Mistakes: Do not allow the elbow of the affected arm to drift away from your body. Keep the movement horizontal and slow.

Exercise 3: Shoulder Pulley Flexion

Purpose: To utilize a pulley system to passively lift your affected arm using the downward pull of your healthy arm.

Equipment Needed: An over-the-door shoulder pulley system.

Starting Position: Sit comfortably in a chair facing away from the door where the pulley is mounted. Ensure the pulley is securely anchored.

Instructions:

Hold one handle of the pulley in each hand, with your arms relaxed at your sides.
Using your healthy arm, pull down on its handle, which will slowly lift your affected arm forward and upward.
Lift the affected arm as high as comfortable, allowing it to relax completely as the pulley does the lifting work.
Hold the elevated position for 5 seconds.
Slowly lower the affected arm back down by controlling the release with your healthy arm.

Dosage: Perform 10 to 15 repetitions, 1 to 2 times per day.

Tips/Common Mistakes: Keep the affected arm as relaxed as possible—let the pulley and your healthy arm do all the work. Do not shrug your shoulder up as you lift.

Exercise 4: Wall Slides (Active-Assisted)

Purpose: To slide your hand up a wall to assist with raising your arm, utilizing the wall to support the weight of your arm.

Equipment Needed: A smooth wall surface. A small towel or washcloth under your hand can help it slide more easily.

Starting Position: Stand facing the wall, about a half-step away. Place the pinky side of your hand (or both hands) against the wall at chest height, with elbows bent.

Instructions:

Gently press your hand against the wall.
Slowly slide your hand up the wall, straightening your elbow and reaching upward as far as comfortable.
As you reach the top, take a small step closer to the wall if you need to deepen the stretch safely.
Hold the stretch at the highest comfortable point for 5 to 10 seconds.
Slowly slide your hand back down to the starting position.

Dosage: Perform 10 to 15 repetitions, 1 to 2 times per day.

Tips/Common Mistakes: Do not lean forward or arch your back to push your arm higher. If sliding is difficult, use a towel under your hand to reduce friction.

Always consult with your physical therapist or doctor before starting a new exercise routine. If any exercise causes persistent pain or swelling, discontinue it and contact your healthcare provider.

Disclaimer: This guide provides general exercise instructions 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.

Browse all articles

Periscapular Strengthening Exercises

Step-by-step home exercise guide for periscapular strengthening to prioritize the serratus anterior and lower trapezius, creating a stable base for an unstable joint.

Dr. Christian Veillette

Jul 5, 2026

Acromioclavicular (AC) Joint Sprain (Grades I-II) Protocol

Phase-by-phase rehabilitation protocol for Acromioclavicular (AC) Joint Sprain (Grades I-II) focusing on early stabilization and avoiding heavy lifting during the acute phase.

Dr. Christian Veillette

Jul 5, 2026