Shoulder impingement vs frozen shoulder: symptoms, diagnosis and treatment

Shoulder pain is one of the most common reasons for orthopaedic consultation, but not all discomfort in that area is due to the same thing. Subacromial impingement and adhesive capsulitis – known as frozen shoulder – are two different conditions. Although they may look similar at first glance, they have different causes, evolution and treatments. Therefore, distinguishing shoulder impingement vs frozen shoulder is the first step to recover effectively.

What is shoulder impingement?

Shoulder impingement occurs when the tendons of the rotator cuff are compressed within the subacromial space when you lift your arm. That repeated compression causes inflammation and pain and, over time, can end up affecting the soft tissues surrounding the joint.

Causes of Subacromial Impingement

Among the most common causes are the repetitive use of the arm above the head, maintaining poor posture for a long time and the degenerative changes of age. Certain anatomical variants of acromion or the presence of bone spurs can also play a role, reducing the space available for tendons.

Rotator cuff relationship

The rotator cuff is the set of muscles and tendons that helps stabilize the shoulder. When the impingement becomes recurrent, those tendons can become inflamed and, in more advanced cases, partially or completely torn. This usually increases pain and further limits shoulder movement.

What is frozen shoulder or adhesive capsulitis?

Frozen shoulder, or adhesive capsulitis, is a condition in which the joint capsule of the shoulder becomes inflamed, thickened, and forms scar tissue. The result is a stiffness that progresses slowly and can almost completely impede movement. According to information published by the American Academy of Orthopaedic Surgeons, it mainly affects people between 40 and 60 years of age and is more common in women.

Anatomy of the joint capsule

The joint capsule is an envelope of fibrous tissue that surrounds the glenohumeral joint and contains the synovial fluid that lubricates movement. In adhesive capsulitis, that capsule contracts and loses elasticity, markedly reducing range of motion.

Causes and Risk Factors of Frozen Shoulder

Risk factors include prolonged immobilization of the arm (for example, after a fracture or surgery), diabetes, thyroid disease, and some cardiovascular disorders. However, in many cases it is not possible to pinpoint a single cause.

Key Differences Between Shoulder Impingement and Frozen Shoulder

Symptom Comparison: Pain vs Stiffness

In subacromial impingement, what stands out the most is the pain when raising the arm or when making certain movements, especially between 60 and 120 degrees of elevation. In adhesive capsulitis, on the other hand, the main symptom is usually stiffness: the person feels that the shoulder “does not give” in any direction, even if they try to move forcefully.

Shoulder Mobility: Limitations and Movement Patterns

In impingement, active mobility may be limited by pain, but passive mobility—when someone else moves the patient’s arm—is usually maintained. In frozen shoulder, both active and passive mobility are greatly diminished, and that’s one of the most useful clinical clues to differentiating this. In capsulitis, external rotation is usually the most affected movement. In capsulitis, external rotation is usually the most affected movement.

Inflammation and scar tissue

Impingement causes more localized inflammation in the subacromial bursa and rotator cuff tendons. Frozen shoulder, on the other hand, is associated with the formation of scar tissue within the joint capsule, which explains why the loss of movement progresses progressively, even when the pain changes over time.

Stages of evolution of frozen shoulder

Freezing phase

This is the first stage and can last between two and nine months. The pain gradually increases and mobility begins to reduce. Often, the discomfort is most noticeable at night.

Frozen phase

In this phase, the pain may go down a little, but the stiffness peaks. It can last from four to twelve months and is usually the stage that most affects day-to-day activities.

Defrosting phase

Mobility is progressively restored. This process can take between six months and two years. With proper physiotherapy and consistency, most people manage to recover normal shoulder function.

Diagnosis: How to Tell a Pinch from a Frozen Shoulder

Medical examination and physical examination

Diagnosis begins with a careful clinical evaluation. The specialist checks the active and passive range of motion, locates pain, and performs specific maneuvers. For example, the Neer and Hawkins-Kennedy tests are used for impingement, while loss of external rotation is a typical finding in adhesive capsulitis.

Imaging tests: X-rays and MRI

X-rays help rule out bone changes, such as spurs or calcifications. MRI allows you to see the soft tissues in more detail: rotator cuff tendons, joint capsule, and subacromial bursa. Studies published in the Journal of Shoulder and Elbow Surgery note that MRI is especially useful for measuring capsular thickening in adhesive capsulitis.

External rotation and other mobility tests

Limitation of passive external rotation is usually the most guiding factor toward frozen shoulder. If that rotation is maintained, it is more likely to be a subacromial impingement or another rotator cuff-related injury.

Treatment of shoulder impingement

Nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs are usually the first choice for controlling pain and inflammation in the pinch. It is important that their use is supervised by a health professional, especially if there is a history of gastric or kidney problems.

Physical therapy and strengthening exercises

Physical therapy is the foundation of treatment. Exercises to strengthen the rotator cuff and the muscles that stabilize the scapula help improve shoulder mechanics, reduce subacromial compression, and prevent relapses.

Steroid Injections for Clamping

If the pain does not improve with conservative measures, steroid injections into the subacromial space can provide significant relief in the short to medium term, which also allows for a more comfortable resumption of physical therapy.

Treatment of frozen shoulder

Non-surgical treatment: intra-articular corticosteroids

Intra-articular corticosteroids decrease inflammation within the joint capsule and reduce pain, especially during the freezing phase. Their effect is usually more sustained when accompanied by a well-structured exercise plan.

Codman’s stretching and pendulum exercises

Gentle stretches and the Codman pendulum — where the arm hangs relaxed and moves in small circles — help preserve range of motion without aggravating inflammation. Ideally, you should do them progressively and steadily.

Surgical treatment: manipulation under anesthesia and shoulder arthroscopy

When the case does not respond to conservative treatment, manipulation under anesthesia or shoulder arthroscopy may be considered to release adhesions from the joint capsule. These options can accelerate the recovery of mobility if non-surgical measures have not been sufficient. These options can speed up the recovery of mobility if non-surgical measures have not been sufficient.

Recommended exercises according to your condition

Exercises to regain mobility in frozen shoulder

Codman’s pendulum, external rotation stretches with a cane, and sliding exercises on a surface are usually indicated. They should be done within the tolerable range, without forcing a sharp pain.

Strengthening Exercises for Subacromial Impingement

In impingement, external rotation exercises with an elastic band, elevation in the plane of the scapula and strengthening of the serratus anterior work very well. The objective is to correct the altered mechanics that are favoring compression.

Red flags and when to consult a specialist

See an orthopedic specialist if you have persistent nighttime pain that disrupts sleep, if you can’t lift your arm above your shoulder, if you notice stiffness that doesn’t improve after several weeks, or if the problem gets progressively worse without a clear cause. Catching it early allows you to better manage it and reduce the risk of long-term complications.

At COPAC (Panama Clinic Orthopedic Center), located at The Panama Clinic, Tower B, 23rd Floor, Office 2315, a team of orthopedic and traumatology specialists performs personalized evaluations to accurately determine if it is a subacromial impingement, adhesive capsulitis or another shoulder condition. You can schedule your consultation by WhatsApp at +507 6090-8815, by calling +507 310 2866 or writing to recepcion@copac.com.pa.

Frequently Asked Questions About Shoulder Impingement vs Frozen Shoulder

If you need clarification on whether it’s shoulder impingement vs frozen shoulder, a timely assessment makes all the difference in treatment and recovery.