Diagnosis and reassurance.
Typical presentationSymptoms and function.
Why it happensBiomechanics and tissue loading.
Assessment & differential diagnosisClinical reasoning.
Where ultrasound helpsDiagnosis and guidance.
Treatment strategyPhysio, injections and rehab.
Evidence strength summaryPlain-English interpretation.
Harvard referencesTopic-specific citations.
Frozen shoulder and shoulder impingement can both make lifting the arm painful, but they are not the same problem. Frozen shoulder usually produces marked stiffness and a capsular pattern of restriction. Impingement or subacromial pain syndrome is more likely to involve painful movement, cuff overload and variable loss of movement rather than true global stiffness.
Typical presentation
Frozen shoulder often starts with increasing pain, especially at night, then progresses into notable stiffness. People commonly say they cannot reach behind the back, wash hair properly or get the arm overhead even if they try. Impingement-like pain is usually more linked to a painful arc, overhead loading, reaching and cuff demand, with movement limited by pain rather than the same hard capsular block.
Why the two feel different
Frozen shoulder is largely a capsular inflammatory and fibrotic condition. The capsule thickens and tightens, reducing joint volume and restricting movement. Shoulder impingement, more accurately discussed today within rotator cuff related shoulder pain or subacromial pain syndrome, usually reflects tendon overload, bursal irritation, cuff weakness or poor load transfer rather than the same capsular contracture.
Assessment and differential diagnosis
The most useful examination question is whether the shoulder is truly stiff in multiple directions or simply painful. Frozen shoulder typically shows a clearer loss of passive external rotation and a more classic capsular pattern. Impingement-like pain often preserves more passive motion, especially when the shoulder is calm enough to assess properly. Differential diagnosis also includes calcific tendinopathy, cuff tear and glenohumeral osteoarthritis.
Where ultrasound helps
Ultrasound is more valuable for the impingement side of the differential than for diagnosing frozen shoulder directly, because it can identify cuff tendinopathy, bursitis, tears or calcification. It can still support frozen shoulder assessment by showing reduced joint recess expansion or coexisting pathology, and it is useful when deciding whether a guided injection should target the glenohumeral joint or the subacromial bursa.
Treatment strategy
Frozen shoulder often needs a more staged plan with pain control, patient education, cautious mobility and selective glenohumeral injection in the painful phase. Impingement-like pain usually responds better to progressive cuff loading, scapular control, movement confidence and load management, with subacromial injection reserved for selected irritable cases. Choosing the wrong pathway is one of the main reasons patients get stuck.
Evidence strength summary
Research supports different treatment routes for these diagnoses. Frozen shoulder may benefit from early pain-reduction strategies including intra-articular injection in selected patients, while rotator cuff and subacromial pain are more reliably improved by active rehabilitation, with injection considered as an adjunct rather than a cure.
Page-specific FAQs
How can I tell which one I have?
The biggest clue is whether the shoulder is truly stiff in multiple directions. A painful but less stiff shoulder is more likely to fit a cuff or subacromial pattern.
Can ultrasound decide between them?
It can help, especially when there is doubt about tendon, bursa or calcific involvement, but the final diagnosis still depends on clinical assessment.
Does treatment differ a lot?
Yes. Frozen shoulder and impingement-like pain usually need different priorities, especially when deciding on exercise intensity and injection target.
Harvard references
- Lewis, J. (2016) Rotator cuff related shoulder pain: assessment, management and uncertainties. Manual Therapy, 23, pp.57–68.
- Hegedus, E.J. et al. (2015) Physical examination tests of the shoulder: a systematic review with meta-analysis. British Journal of Sports Medicine, 49(20), pp.1311–1321.
- Naredo, E. et al. (2002) Painful shoulder: comparison of physical examination and ultrasonographic findings. Annals of the Rheumatic Diseases, 61(2), pp.132–136.
- Sconfienza, L.M. et al. (2012) Clinical indications for musculoskeletal ultrasound. European Journal of Radiology, 81(12), pp.3677–3689.
- Rhon, D.I. et al. (2022) Conservative care versus procedural care in common shoulder disorders: pragmatic evidence synthesis. Journal of Orthopaedic & Sports Physical Therapy, 52(7), pp.1–15.
- Lin, M.T. et al. (2019) Comparative effectiveness of injection therapies in shoulder disorders: systematic review. Archives of Physical Medicine and Rehabilitation, 100(2), pp.336–349.
- National Institute for Health and Care Excellence (2022) Osteoarthritis in over 16s: diagnosis and management. NICE guideline NG226.
- American Academy of Orthopaedic Surgeons (2020) Management of rotator cuff injuries clinical practice guideline.
Most patients choose a same-visit diagnostic pathway
For suitable cases we can assess, explain the likely diagnosis, use ultrasound where it adds value, and discuss whether rehabilitation alone or rehabilitation plus a guided injection is the most sensible next step.