Some shoulders hurt at a specific point in the movement and nowhere else. Raising the arm out to the side is fine for the first third, painful through the middle, and fine again at the top. That middle zone, roughly 60 to 120 degrees of elevation, is the painful arc.
It is one of the oldest named signs in shoulder examination and one of the most informative, because the angle at which pain appears tells you which structure is being loaded. This guide explains what is happening inside the shoulder at each stage of the arc, the three arc patterns we see in clinic, and what each one points to.
Key takeaways
- The painful arc is pain during a specific segment of arm elevation, classically 60 to 120 degrees, with less or no pain before and after.
- Between 60 and 120 degrees, the bony point at the top of the arm passes directly under the acromion. The subacromial space is at its narrowest.
- A mid-arc pattern points to the rotator cuff tendons or bursa. An end-arc pattern above 170 degrees points to the AC joint. Pain throughout the arc points to the joint itself.
- Pain that appears only on the way down suggests the cuff is not controlling the lowering, and raises the question of a tendon problem.
- The arc is a sign, not a diagnosis. It tells you where to look. Assessment tells you what is there.
What the painful arc is
The painful arc is a segment of arm elevation during which pain appears and then eases as the arm continues past it.
The term dates from a 1977 study of 97 patients that classified shoulder pain by where in the arc it occurred and which structure was responsible. The modern umbrella term for the mid-arc pattern is subacromial pain syndrome, which has replaced “impingement syndrome” in most guidelines. The sign itself has not changed. The arm is raised slowly out to the side with the thumb up, and the person reports the angle at which pain starts and stops.
A painful arc is one of the symptom dimensions of shoulder pain that most clearly maps to anatomy, because the angle is the clue.
Why the pain sits between 60 and 120 degrees
The greater tuberosity of the humerus passes directly beneath the acromion between 60 and 120 degrees of elevation, and the structures between them are compressed.
0 to 60 degrees: the space is open
As the arm starts to rise, the ball of the joint sits low in its socket. The gap between the top of the arm bone and the bony arch above it is at its widest. The supraspinatus tendon and the bursa over it have room. Most people with a painful arc are comfortable here.
60 to 120 degrees: the space closes
The greater tuberosity, the bony knob at the top of the arm bone where the cuff tendons attach, swings up and under the acromion. The gap narrows to a few millimetres. Anything in that gap that is swollen, thickened, or inflamed is squeezed. If the rotator cuff is not pulling the ball down to make room, or the shoulder blade has not started rotating upward to lift the arch out of the way, the squeeze is harder. This is the pinch zone.
120 to 180 degrees: the space opens again
The tuberosity clears the acromion. The shoulder blade has rotated upward and the arch has moved out of the path. Pain from the subacromial structures eases. If pain continues or appears for the first time in the last 10 to 20 degrees, a different structure is responsible.
The three arc patterns and what each points to
The angle at which pain appears and disappears identifies the likely structure. Three patterns cover most cases.
| Pattern | Where pain sits | Likely structure | Typical story |
| Mid-arc | 60 to 120 degrees, eases above | Supraspinatus tendon or subacromial bursa | Reaching, overhead work, lying on that side |
| End-arc | 170 to 180 degrees only | Acromioclavicular (AC) joint | Pain at the bony point on top of the shoulder, worse reaching across the body |
| Whole-arc | Pain and stiffness throughout, including when someone else moves the arm | Glenohumeral joint or capsule | Global stiffness, often frozen shoulder or joint arthritis |
A fourth pattern worth knowing: pain on the way down
Some people raise the arm through the arc with mild discomfort and then get sharp pain, or the arm drops, as they lower it through the same zone. Lowering the arm slowly is controlled by the cuff working under load. Pain or loss of control on the way down points to the cuff tendon itself and raises the question of a tear rather than irritation. That differential is covered in our guide to rotator cuff tear vs strain.
How the arc is assessed in clinic
The arc on its own is a weak diagnostic test. Combined with two further observations, it becomes useful.
A meta-analysis of shoulder examination tests put the painful arc at 53% sensitivity and 76% specificity for subacromial pain. On its own, that means a positive arc is suggestive and a negative arc rules little out. In clinic we add two observations:
- Active versus passive. You raise the arm, then we raise it for you with your muscles relaxed. If the arc is painful both ways, a structure is being compressed regardless of muscle control. If it is painful only when you do it, the way your cuff and shoulder blade are controlling the movement is the driver.
- Scapular assist. We hold the shoulder blade and help it rotate upward as you raise the arm. If the arc disappears, the shoulder blade is not doing its job and that is the treatment target. If the arc stays, the problem is in the subacromial space itself.
Those two observations, together with the self-test cluster described in our shoulder impingement self-test, are what turn the arc into a working diagnosis.
What changes a painful arc
A mid-arc pattern improves when the space is restored by better cuff and shoulder blade control, not by avoiding the arc.
People with a painful arc learn to avoid it. They reach with the elbow bent, swing the arm forward instead of sideways, or use the other hand. The arc stays painful because the mechanics that narrow the space are unchanged.
Our shoulder impingement service treats the arc by:
- Retraining the cuff to depress and centre the ball of the joint as the arm rises, which widens the space through the pinch zone.
- Restoring upward rotation of the shoulder blade so the acromion lifts out of the path earlier in the arc.
- Reducing bursal irritation in the short term with load management, so the retraining can happen without flare.
- Rebuilding the arc under load, so overhead reaching is restored rather than avoided.
For an end-arc pattern, treatment targets the AC joint instead. For a whole-arc pattern, the joint capsule is assessed first. Getting the pattern right is what makes private impingement physiotherapy effective, because the same exercises given to the wrong pattern do nothing.
Frequently asked questions
What is painful arc syndrome?
Painful arc syndrome is shoulder pain that appears during a specific segment of arm elevation, classically between 60 and 120 degrees, and eases above it. It is a clinical sign, most often caused by compression of the rotator cuff tendons or bursa beneath the acromion.
Why does my shoulder only hurt at a certain angle?
Because the structures under the bony arch of the shoulder are compressed only while the top of the arm bone passes beneath it, which happens between 60 and 120 degrees. Below and above that zone the space is open and the pain eases.
Is a painful arc the same as shoulder impingement?
A mid-arc painful arc is the classic sign of shoulder impingement, now usually called subacromial pain syndrome. Not every painful arc is impingement. Pain only at the top of the movement points to the AC joint, and pain throughout points to the joint itself.
What does pain at the top of the arc mean?
Pain only in the last 10 to 20 degrees of elevation, usually felt on the bony point at the top of the shoulder, points to the acromioclavicular joint rather than the rotator cuff. It is treated differently from a mid-arc pattern.
Can a painful arc go away on its own?
Sometimes, if the activity that irritated the space is stopped. It usually returns when the activity resumes, because the mechanics have not changed. Physiotherapy that restores cuff and shoulder blade control is what changes the pattern for good.
Book a shoulder assessment
If your shoulder hurts at a specific point in the arc, the angle has already told you something. The One Body LDN shoulder pain team assesses the arc actively and passively, checks the shoulder blade, and identifies which structure is responsible before treatment starts. You can book a shoulder assessment at any of our London clinics without a GP referral.
Note: shoulder symptoms that need medical review first
See a GP or contact NHS 111 before physiotherapy if the painful arc comes with:
- A sudden inability to raise the arm after an injury or fall
- A visibly deformed shoulder
- A hot, red, swollen shoulder, or shoulder pain with fever
- Shoulder pain with chest pain, breathlessness, or pain spreading down the left arm
- Numbness or weakness through the whole arm
- Unexplained weight loss or a history of cancer
References
- NHS. Shoulder pain.
- Kessel L, Watson M. The painful arc syndrome. Clinical classification as a guide to management.
- Hegedus EJ, Goode AP, Cook CE, et al. Which physical examination tests provide clinicians with the most value when examining the shoulder? Update of a systematic review with meta-analysis of individual tests.
- Diercks R, Bron C, Dorrestijn O, et al. Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association.
- Chartered Society of Physiotherapy. Shoulder pain: managing your pain at home.
