Spur vs Calcification Difference Under Ultrasound

Spur vs Calcification Difference Under Ultrasound

Introduction

Musculoskeletal ultrasound has revolutionized pain medicine by allowing real-time visualization of joints, bones, tendons, and entheses. Among the most common findings are spur and calcification. Both appear hyperechoic (bright) on ultrasound, but their origin, pathology, and management are very different. Misinterpreting them can lead to diagnostic errors and suboptimal treatment.

This article explains the difference between spur and calcification under ultrasound, their sonographic appearances, and the clinical importance for pain physicians.

What is a Spur?

A spur, or osteophyte, is a bony outgrowth that develops at the margins of bones or entheses, often seen in osteoarthritis or chronic mechanical stress.

Ultrasound Appearance of Spur

• Continuous with the cortical bone surface

• Appears as a sharp hyperechoic projection altering the smooth contour of bone

• Always connected to bone cortex

• Produces a posterior acoustic shadow

👉 Clinically, spurs are common in weight-bearing joints (knee, hip, ankle) and at tendon insertions (e.g., Achilles).

What is a Calcification?

Calcification refers to calcium deposition within soft tissues such as tendon, bursa, capsule, or muscle. The most typical presentation is calcific tendinitis of the rotator cuff.

General Ultrasound Appearance of Calcification

• Hyperechoic foci within soft tissue (not attached to cortex)

• Posterior acoustic shadowing may or may not be present

• Variable shape and definition depending on stage

Different Appearances of Calcification Under Ultrasound

Calcifications do not always look the same. Their echogenicity and shadowing vary with disease stage:

1. Dense (Hard) Calcification

• Bright, sharply defined hyperechoic focus

• Strong posterior acoustic shadow

• Seen in chronic calcific tendinitis

2. Intermediate Calcification

• Moderately hyperechoic, irregular or granular margins

• Faint or partial shadowing

• Represents partial mineralization

3. Soft or Fluffy Calcification

• Poorly defined, cloud-like echogenicity

• Minimal or no shadowing

• Typically in acute/resorptive phase

• Often painful, may show hyperemia on Doppler

4. Fluid-Calcific Mixture

• Heterogeneous echogenic material in hypoechoic background

• Indicates liquefaction of calcium

• Best treated with US-guided lavage/barbotage

5. Migrated Calcification

• Hyperechoic foci within adjacent bursa or soft tissue

• Example: leakage into subacromial-subdeltoid bursa

• Can mimic loose bodies

Spur vs Calcification Difference Under Ultrasound : A Comparative Summary

Feature	Spur	Calcification
Origin	Bony outgrowth (osteophyte)	Calcium deposits in soft tissue
Location	Bone margin, enthesis	Tendon, bursa, capsule, muscle
Continuity with Cortex	Always continuous	Not attached
Acoustic Shadow	Consistent	Variable
Example	Osteophyte in knee OA	Supraspinatus calcific tendinitis

Clinical Relevance for Pain Physicians

• Spur → Indicates chronic bone remodeling and structural degeneration. Management focuses on long-term OA care and mechanical correction.

• Calcification → Often acutely painful, particularly in tendons. Treatment may include ultrasound-guided needling, lavage, steroid injection, or shockwave therapy.

👉 Correct differentiation ensures appropriate intervention, prevents unnecessary procedures, and improves patient outcomes.

For hands-on training in ultrasound-guided pain interventions, explore our fellowship and workshops at Asian Pain Academy.

❓ Frequently Asked Questions (FAQ)

1. What is the difference between spur and calcification under ultrasound?

A spur is a bony outgrowth continuous with the bone cortex, while calcification is a calcium deposit in soft tissue like tendons, bursae, or muscles. Spurs always connect to bone; calcifications are separate.

2. How do calcifications look different under ultrasound?

Calcifications may appear as:

• Dense and hard (sharp, bright, with shadow),

• Fluffy or soft (ill-defined, no shadow),

• Intermediate (granular, partial shadow),

• Fluid-calcific mixture (heterogeneous with liquefied areas),

• Or migrated deposits into adjacent bursae.

3. Are spurs and calcifications treated the same way?

No. Spurs are usually managed conservatively or as part of long-term osteoarthritis care. Calcifications can often be treated with ultrasound-guided interventions like lavage, barbotage, needling, or shockwave therapy.

4. Can ultrasound differentiate spur from calcification better than X-ray?

Yes. X-ray shows both as white opacities but cannot always localize them. Ultrasound clearly shows continuity with bone (spur) versus soft tissue deposits (calcification), making it more accurate in MSK and pain practice.

5. Which joints are most commonly affected?

• Spurs: knees, hips, ankles, and enthesis sites such as the Achilles tendon.

• Calcifications: shoulders (supraspinatus tendon), elbows, hips, and sometimes wrist tendons.

6. Are all calcifications painful?

Not always. Some calcifications are asymptomatic and discovered incidentally. Pain is more likely in the resorptive phase when deposits are soft or fluffy and cause inflammation.

7. Is ultrasound-guided treatment safe for calcific tendinitis?

Yes. Ultrasound-guided lavage, needling, or barbotage are minimally invasive, effective, and safe when performed by trained pain physicians or MSK specialists.

Conclusion

While both spur and calcification appear bright on ultrasound, their nature is fundamentally different.

• Spurs are cortical bone projections continuous with the skeleton.

• Calcifications are calcium deposits in soft tissue, with appearances ranging from fluffy to dense.

For pain physicians and MSK sonologists, recognizing Spur vs Calcification Difference Under Ultrasound is critical in diagnosis, prognosis, and intervention planning.

References

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2. Chiou HJ, Chou YH, Wu JJ, Hsu CC, Huang DY, Chang CY. Evaluation of calcific tendonitis of the rotator cuff: role of color Doppler ultrasonography. J Ultrasound Med. 2002;21(3):289–295.

3. Farin PU, Räsänen H, Jaroma H, Harju A. Rotator cuff calcifications: treatment with US-guided technique. Radiology. 1996;201(3):711–713.

4. Bardowski EA, Adler RS. Sonographic evaluation of musculoskeletal calcifications and ossifications. Ultrasound Q. 2019;35(3):201–212.

5. Bianchi S, Martinoli C. Ultrasound of the Musculoskeletal System. Springer, 2007.

6. Klauser AS, Martinoli C. Ultrasound of the musculoskeletal system: what is of interest to the pain specialist? Curr Pain Headache Rep. 2012;16(1):43–49.