Calcific Tendinitis of the Shoulder

The paradox to hold on to: the most painful phase is the healing one. Resorption is when the body is removing the deposit, and it is when the patient presents in agony - which is why the natural history argues for waiting even when the pain argues for operating. That makes this condition the opposite of the shoulder problems it is mistaken for: rotator cuff tears and subacromial impingement do not resolve by being left alone, and adhesive capsulitis is self-limiting but over years rather than months and is defined by stiffness rather than a deposit. The same crystal deposited elsewhere is calcific periarthritis / hydroxyapatite deposition, which is worth knowing because it shows this is a systemic tendency presenting at one site, not a local injury.

Who gets it. Calcific deposits are found on the radiographs of roughly 3-7% of adults and are often asymptomatic. Peak age is 30-50 years with a female predominance; diabetes carries a strong metabolic association, and hypothyroidism is also recognised.

Natural history. The condition is self-limiting in 80-90% of cases, with the deposit resorbing spontaneously over 1-3 years and symptoms settling before the radiograph clears. That is the counselling the patient needs before any intervention is discussed.

Where the calcium forms. The supraspinatus is affected in 70-80% of cases, the infraspinatus in about 20%, and the teres minor and subscapularis rarely. Within the supraspinatus the deposit sits in the critical zone, 1-2cm from the greater tuberosity insertion, which is the watershed between the osseous and tendinous blood supply and an area of relative hypovascularity.

What the tissue is doing. This is a cell-mediated process, not a degenerative one: tenocytes undergo chondrocyte metaplasia and calcium hydroxyapatite crystals are laid down in the fibrocartilage that results. The trigger is unknown, although the process is associated with hypoxia.

The mechanical context. The tendon is compressed between the acromion and the humeral head and takes repetitive microtrauma, and impingement may coexist. Even so, the pathology is intrinsic tendon metaplasia rather than extrinsic impingement.

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Three systems are in use and each answers a different question. Gartner grades what the radiograph shows, Uhthoff names the pathological phase the tendon is in, and Molé describes the shape of the deposit and separates true calcific tendinitis from degenerative enthesopathy.

What the grade buys you. It is the vascular invasion and inflammation of the resorptive phase that makes the shoulder so painful, so a fluffy, ill-defined deposit is the one that hurts most and the one with the best outlook. A resting deposit is static and is monitored; a dense formative deposit may persist unchanged and only earns an intervention if it stays symptomatic.

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History. The presentation is variable, and the phase is what varies it. A deposit found on a film taken for something else may be entirely asymptomatic, a formative deposit gives a chronic dull ache, and the resorptive phase gives severe acute pain. Night pain is common in the acute phase and the picture may mimic a frozen shoulder; acute severe pain suggests the resorptive phase.

Examination. A painful arc, tenderness over the greater tuberosity, impingement signs that may be positive, and a range of movement limited by pain; in the acute phase the patient may be unable to move the shoulder at all. The presentation has to be differentiated from a rotator cuff tear.

Radiographs. The standard views are AP, supraspinatus outlet and axillary, and the deposit lies in the supraspinatus insertion area. The texture of the deposit is what the Gartner grade records, so a plain film predicts both the phase and the prognosis.

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Ultrasound. This is the working tool: real-time and dynamic assessment, associated bursitis shown directly, and needle guidance during barbotage. It is both the diagnostic and the therapeutic instrument.

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MRI. This is not usually needed. It shows bursal inflammation and bone marrow oedema and rules out other pathology, but it may underestimate the calcific deposit itself.

The same crystal family - basic calcium phosphate (BCP), principally hydroxyapatite - that deposits reversibly in calcific tendinitis can, at the other extreme, drive a destructive arthropathy.

• Milwaukee shoulder is a BCP-crystal (hydroxyapatite) associated arthropathy seen typically in elderly women, characterised by a large, often blood-stained but non-inflammatory joint effusion, a massive rotator cuff tear and rapidly progressive glenohumeral destruction (cuff-tear arthropathy).
• BCP crystals are not birefringent under polarised light (unlike the negatively-birefringent urate of gout or the weakly-positively-birefringent CPPD of pseudogout), so they are easily missed - alizarin red staining or electron microscopy is needed to identify them.
• Management is largely supportive (analgesia, aspiration, activity modification); a reverse total shoulder arthroplasty is the reconstructive option for end-stage cuff-tear arthropathy, because the deficient cuff makes an anatomic replacement fail.

Start with the phase. The acutely painful resorptive deposit is the one to treat conservatively and wait out, because the pain is resorption happening; the dense formative deposit that stays symptomatic is the one that comes to intervention.

Conservative treatment is first-line in both phases. The acute resorptive phase is treated with NSAIDs, ice, activity modification and a subacromial steroid injection; the chronic formative phase with physiotherapy, NSAIDs as needed, and time.

Barbotage is the most effective non-surgical intervention. An ultrasound-guided needle is placed in the deposit, the calcium is aspirated and lavaged, and local anaesthetic and steroid are given; the success rate is 60-80%, and it works best on a formative deposit with soft calcium.

Extracorporeal shock wave therapy is effective for recalcitrant cases and can fragment the calcium, with a success rate of 50-70%. High-energy ESWT is the superior form, and the modality is a good option to exhaust before considering surgery.

Surgery is for genuine failure: conservative treatment for six months or more without relief, a failed barbotage and a failed course of ESWT, or a large symptomatic deposit. It is rarely required and the results are excellent.

Algorithm

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Ultrasound-guided barbotage. Position the patient supine or seated and identify the deposit on ultrasound. The two-needle technique sets up a circuit, one needle in and one out:

1. Insert an 18G needle into the deposit under ultrasound guidance
2. Place a second 18G needle as the lavage outflow
3. Inject saline and aspirate the calcium, fragmenting the deposit with the needle as required
4. Inject corticosteroid into the subacromial bursa

The single-needle technique does the same work in cycles: an 18G needle into the deposit, saline injected, a wait, then aspiration of the calcium-saline mixture, repeated several times.

Arthroscopic excision. Beach chair or lateral position, a standard posterior viewing portal, and a diagnostic arthroscopy first to assess the cuff, labrum and biceps. Then:

1. Locate the deposit with a spinal needle under fluoroscopy
2. Incise the bursal surface over the deposit
3. Curette and evacuate the calcium, which is paste-like
4. Avoid excessive debridement of healthy tendon
5. Add a subacromial decompression only where impingement is present
6. Consider a side-to-side repair if the defect is large

Finding it and closing it. The calcium may lie deep within the tendon, which is what makes needle localisation worth the extra minutes. Small defects heal spontaneously and are left alone; repair defects greater than 1cm in transverse dimension.

Why decompression is not routine. Adding a subacromial decompression to the excision does not improve the outcome and lengthens the time to pain-free activity (Marder). Reserve it for the shoulder with genuine coexisting impingement, as in step 5 above.

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After conservative care. Prolonged symptoms are rare in a condition that is usually self-limiting. The other recognised problems are secondary stiffness amounting to a frozen shoulder, and chronic pain if resorption does not occur.

After barbotage. A pain flare is common. The other recognised complications are:

• Infection - rare, less than 0.1%
• Neurovascular injury - rare with proper technique
• Incomplete calcium removal

After arthroscopic excision. The recognised complications are:

• Rotator cuff tear from debridement
• Incomplete excision leaving residual calcium
• Infection - less than 1%
• Stiffness or frozen shoulder - 2-5%
• Failure to improve symptoms

Recurrence after complete resolution is rare, under 10%, and is commoner when the calcium was incompletely removed at surgery.

After barbotage. A sling is used for comfort only for 24-48 hours, with ice and NSAIDs, normal activities as tolerated, and physiotherapy for range and strength. Review at 6-8 weeks with repeat imaging.

After arthroscopic excision. The rehabilitation is staged, protecting the tendon before loading it.

If the cuff was repaired, the standard rotator cuff repair protocol takes over: a sling for 4-6 weeks and no active elevation for 6 weeks.

What predicts a good result. A resorptive-phase deposit is the favourable one because it is going to resolve, and soft and smaller deposits do better. Dense formative deposits, large deposits and an associated cuff tear are the less favourable group.

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Global epidemiology

• Radiographic calcific deposits are found in roughly 3-8% of adults, the majority asymptomatic.
• Peak incidence is in the 30-60 year age group, with a female predominance in most cohorts (around 60-65%).
• The supraspinatus is involved in the large majority of cases; bilateral disease occurs in roughly 10-20% and is a negative prognostic marker (Ogon et al, Arthritis Rheum 2009, PMID 19790063).
• Associations reported across populations include diabetes mellitus, thyroid disorders and a possible genetic/metabolic predisposition, although causation is unproven.

Registry and evidence notes

• Calcific tendinitis is a soft-tissue disorder, so it is not tracked by arthroplasty/implant registries (NJR, AJRR, AOANJRR). The strongest evidence base is from RCTs and meta-analyses rather than registries.
• Pooled RCT evidence (network meta-analysis, PMID 27554465) ranks US-guided needling plus subacromial corticosteroid as the preferred non-surgical option, with high-energy ESWT (PMID 14625334) a reasonable alternative.

High- vs limited-resource practice variation

• In well-resourced settings, ultrasound-guided barbotage and high-energy ESWT are widely available and used early for refractory deposits.
• Where musculoskeletal ultrasound or ESWT machines are scarce, management leans on plain radiographs, analgesia, physiotherapy, and image-free subacromial injection, reserving referral for arthroscopy in persistent cases.
• Across all settings the message is the same: counsel patients on the strongly self-limiting natural history before escalating to any intervention.