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.

Post-Operative Protocols

Pectoralis Major Repair Protocol

Phase-by-phase post-operative rehabilitation protocol for Pectoralis Major Repair to guide recovery and physical therapy.

A structured rehabilitation plan is essential for optimal recovery after surgery. On this page, we outline the phase-based protocol for Pectoralis Major Repair to guide you and your physical therapist through a safe recovery.

This rehabilitation protocol is designed to guide patients and physical therapists through the recovery process following a surgical pectoralis major tendon repair. The primary focus of the early recovery phases is protecting the repaired tendon while gradually restoring joint mobility, followed by a progressive strengthening program to restore full function, strength, and sport or work capacity.

Phase I: Protection & Passive Range of Motion (Weeks 0-6)

The primary goal of this phase is to protect the healing tendon repair, control pain, and prevent joint stiffness through limited passive motion.

Goals: Protect the surgical repair; minimize pain and inflammation; maintain elbow, wrist, and hand mobility; gradually increase passive shoulder motion within safe limits.
Precautions & Restrictions: Sling must be worn at all times (including sleep) except for hygiene and physical therapy; no active shoulder internal rotation or horizontal adduction; no reaching behind the back; passive range of motion limits: flexion to 120 degrees, external rotation to 0 degrees (neutral) with the arm at the side, and abduction to 45 degrees.
Suggested Exercises: Pendulum exercises; passive shoulder flexion (assisted by therapist or pulley) up to 120 degrees; passive external rotation up to neutral (0 degrees); elbow, wrist, and hand range of motion; grip strengthening exercises; submaximal isometric shoulder external rotation and abduction (neutral arm position).
Criteria to Progress: Minimal rest pain; clean, healing surgical incisions; achieved passive range of motion targets (flexion to 120 degrees, external rotation to 0 degrees).

Phase II: Active-Assisted & Active Range of Motion (Weeks 6-12)

During this phase, the patient is gradually weaned from the sling, and active-assisted/active movements are introduced to restore full mobility.

Goals: Wean from the sling; restore full shoulder passive range of motion; initiate active-assisted and active range of motion; establish stable scapular control.
Precautions & Restrictions: Wean from the sling by week 6 to 8 as tolerated; avoid sudden jerking or heavy lifting; no resistance training for the chest muscles; limit external rotation to 30-45 degrees at 90 degrees of abduction until week 8, then progress as tolerated.
Suggested Exercises: Active-assisted range of motion (using a cane or pulley) for flexion, abduction, and external rotation; progress to active range of motion in all planes as muscle control improves; scapular shrugs, retraction, and depression; prone scapular stabilization (I, Y, T positions); gentle posterior capsule stretching.
Criteria to Progress: Full active shoulder flexion and external rotation (at side) equal to the uninjured side; normal scapulohumeral rhythm; pain-free active movement without shoulder hiking.

Phase III: Early Strengthening & Core Stabilization (Weeks 12-18)

Strengthening of the rotator cuff and periscapular muscles is emphasized, and light activation of the pectoralis major begins under controlled conditions.

Goals: Restore full active range of motion in all planes; strengthen the rotator cuff and shoulder girdle stabilizers; initiate gentle, progressive loading of the pectoralis major.
Precautions & Restrictions: No heavy bench press, dumbbell flyes, or chest dips; monitor for anterior shoulder pain; proceed slowly with resistance progressions.
Suggested Exercises: Rotator cuff strengthening (internal and external rotation) using resistance bands or light dumbbells; scapular stabilization (rows, lat pull-downs, scaption); very light pectoralis major loading, starting with submaximal isometrics (squeezing a ball between hands at chest height) and progressing to light resistance band chest press; closed-chain exercises (tabletop weight shifts, quadruped stabilization).
Criteria to Progress: Full, pain-free active range of motion; rotator cuff and periscapular strength at least 4+/5; ability to perform light resistance training without pain or instability.

Phase IV: Advanced Strengthening & Return to Activity (Weeks 18-24+)

This phase focuses on rebuilding peak muscular power, speed, and endurance, and preparing the patient to return to sports or heavy manual labor.

Goals: Restore pre-injury strength and muscular endurance; introduce dynamic, high-velocity movements; safely transition back to full athletic or work activities.
Precautions & Restrictions: Avoid maximal lifting or high-impact chest exercises (maximal bench press, heavy flyes) until at least 6 months post-surgery; always perform a thorough warm-up before lifting.
Suggested Exercises: Progressive resistance training for the chest (incline push-ups progressing to standard push-ups, light to moderate barbell/dumbbell bench press with controlled depth); cable crossovers; medicine ball chest passes and deceleration drills; plyometric push-ups; sport-specific or work-specific simulated tasks.
Criteria to Progress: Shoulder strength at least 90% of the contralateral side; pain-free performance of all functional activities; clearance from the orthopedic surgeon.

These guidelines represent a standard rehabilitation protocol. Individual recovery rates vary significantly depending on the size of the repair, bone/tissue quality, and general patient health. Your surgeon may modify this protocol specifically for you.

Disclaimer: This protocol is for educational purposes and is not a substitute for professional medical advice. Always consult your surgeon or physical therapist before performing any exercises or modifying activity restrictions.

Browse all articles

Arthroscopic Labral Debridement / Repair & Cyst Decompression Protocol

Phase-by-phase post-operative rehabilitation protocol for Arthroscopic Labral Debridement / Repair & Cyst Decompression to guide recovery and physical therapy.