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Shoulder · Tendon

Shoulder impingement (subacromial pain syndrome)

"Impingement" is now called subacromial pain syndrome: the tissues under the bony roof of the shoulder (the acromion) become sensitive—the supraspinatus tendon, the long biceps tendon and a fluid sac called the bursa. It is usually not caused by a single injury and does not always mean anything is torn.

CompleteSource: Rehab Science · Ch 16 · PDF pp. 365–369Shoulder Pain protocol →What should I avoid?
4.1

Overview

📖 Rehab Science
Medical name
Subacromial pain syndrome (SAPS)
Common name
Shoulder impingement
Structures involved
SupraspinatusSubacromial bursaLong-head biceps tendonAcromion

"Impingement" is now called subacromial pain syndrome: the tissues under the bony roof of the shoulder (the acromion) become sensitive—the supraspinatus tendon, the long biceps tendon and a fluid sac called the bursa. It is usually not caused by a single injury and does not always mean anything is torn.

Source: Rehab Science · Ch 16 · PDF pp. 365, 366· 2 original research citationsshow sources ▾
  1. [Ch 16·7] 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. Acta Orthop. 2014;85(3):314-322. find original ↗
Also cited by the book on these pages:
  1. [Ch 16·6] Eajazi A, Kussman S, LeBedis C, et al. Rotator cuff tear arthropathy: pathophysiology, imaging characteristics, and treatment options. AJR Am J Roentgenol. 2015;205(5):W502-W511. find original ↗

Page numbers are those of the uploaded PDF edition. "Find original" opens a PubMed search for the cited study.

4.2

Anatomy & biomechanics

ℹ Additional explanation

The space under the acromion is narrow; the tendon and bursa sit in it like a cable under a bridge.

Interactive diagram · Shoulder complex
SupraspinatusRight shoulder seen from the front · schematic, not to scale · tap a structure
Original schematic. Anatomy is additional educational explanation; clinical relevance links to Rehab Science Ch 16 (PDF pp. 358–462).
4.3

Signs & symptoms

📖 Rehab Science
Pain locationTop, side or front of the shoulder, may refer down the outer upper arm.
Pain characteristicsDull ache at rest, sharp when the subacromial structures are stressed.
At restDull ache; often worse lying on the painful side.
With movementPainful at certain points of the overhead range, even without trauma.
Source: Rehab Science · Ch 16 · PDF p. 366show sources ▾

Page numbers are those of the uploaded PDF edition. "Find original" opens a PubMed search for the cited study.

4.4

Why does this happen?

📖 Rehab Science
Established mechanisms
  • Repetitive overhead use / irritation
  • Inflammation of subacromial structures
Possible contributing factors
  • Bone spur under the acromion
  • Small cuff or biceps tear (worst case)
Source: Rehab Science · Ch 16 · PDF pp. 366, 367· 2 original research citationsshow sources ▾
Also cited by the book on these pages:
  1. [Ch 16·8] Pieters L, Lewis J, Kuppens K, et al. An update of systematic reviews examining the effectiveness of conservative physical therapy interventions for subacromial shoulder pain. J Orthop Sports Phys Ther. 2020;50(3):131-141. find original ↗
  2. [Ch 16·9] Haik MN, Alburquerque-Sendín F, Moreira RF, Pires ED, Camargo PR. Effectiveness of physical therapy treatment of clearly defined subacromial pain: a systematic review of randomised controlled trials. Br J Sports Med. 2016;50(18):1124-1134. find original ↗

Page numbers are those of the uploaded PDF edition. "Find original" opens a PubMed search for the cited study.

4.5

Aggravating factors

📖 Rehab Science
Movement / activityWhy it may cause symptomsTemporary modification
Reaching overheadNarrows the subacromial space under load.Stay below the painful part of the range; progress range gradually.
Sleeping on the painful sideSustained compression of the bursa and tendon.Change sleeping side.
Lifting with an extended armLong lever increases cuff load.Keep loads close to the body.

Aggravating factors are temporary—tissues are sensitised or not ready yet. The protocol rebuilds capacity so these tasks become comfortable again.

Source: Rehab Science · Ch 16 · PDF p. 366show sources ▾

Page numbers are those of the uploaded PDF edition. "Find original" opens a PubMed search for the cited study.

4.6

Assessment & tests

A. Safe self-observations
B. Clinical tests (professional only)
C. Imaging & investigations

Imaging may identify a bone spur or full-thickness tear if 8–12 weeks of modified activity and rehab fail.

No single positive test proves a diagnosis. Clinical tests are interpreted together with history and examination by a trained professional.

4.7

Differential considerations

📖 Rehab Science
Rotator cuff injury (tear / tendinopathy) — Trauma history and clear weakness suggest a tear.
Biceps tendinopathy (long head) — Front-of-shoulder pain, worse with the arm behind the body; protocols are similar.
Shoulder instability (labral tear, dislocation, subluxation) — Feelings of slipping, catching or apprehension point to instability.

Conditions with overlapping symptoms may need professional assessment to tell apart.

4.8

Treatment & recovery

📖 Rehab Science
Prognosis: Pain and function typically return to normal within 4–12 weeks of an appropriate rehab programme. Source: Rehab Science · PDF p. 367

Rehab is the main treatment: shoulder mobility and rotator cuff strengthening using the same Shoulder Pain protocol. Surgery may be considered for a bone spur, a large tear, or no improvement with rehab. The exercises also work before or after surgery if they do not cause pain.

Diagram · The three-phase frameworkOriginal illustration
1Calm it down• Reduce pain; modify aggravators• Soft tissue, mobility, isometricsProgress when:No pain at rest≤ 3/10 with the exercisesinflammatory phase2Restore movement• Range of motion & control• Isometric + eccentric loadingProgress when:Full range with controlMild-to-no painmaturation phase3Build capacity• Full-range resistance training• Progressive overload; sportProgress when:Pain resolved — keeptraining to prevent recurrenceremodelling phase
The same framework treats pain and injury. Progression is driven by symptoms and function—not by days—and with injury it also respects tissue healing time. — Based on concepts in Rehab Science Ch 5 (PDF pp. 80–82), Ch 10 (PDF pp. 182–190), Ch 11 (PDF p. 203).
Source: Rehab Science · Ch 16 · PDF p. 367· 2 original research citationsshow sources ▾
  1. [Ch 16·8] Pieters L, Lewis J, Kuppens K, et al. An update of systematic reviews examining the effectiveness of conservative physical therapy interventions for subacromial shoulder pain. J Orthop Sports Phys Ther. 2020;50(3):131-141. find original ↗
  2. [Ch 16·9] Haik MN, Alburquerque-Sendín F, Moreira RF, Pires ED, Camargo PR. Effectiveness of physical therapy treatment of clearly defined subacromial pain: a systematic review of randomised controlled trials. Br J Sports Med. 2016;50(18):1124-1134. find original ↗

Page numbers are those of the uploaded PDF edition. "Find original" opens a PubMed search for the cited study.

AMBER — get assessed before starting rehab
See a doctor if you have modified aggravating activities and done rehab for 8–12 weeks without improvement; imaging can identify a bone spur or full-thickness tear. Source: Rehab Science · PDF pp. 368, 369
4.9

Prevention

📖 Rehab Science

Continue phase 3 shoulder strengthening; build overhead training volume gradually.

Injury prevention principles → · Return-to-sport stages →