Early Freezing Phase
Synovial lining inflames, shoulder stiffens, pain climbs steadily.
- 2–9 mo: Freezing phase duration (typical range)
- ↓ up to 70%: Capsule volume loss (vs healthy joint)
- 2–5%: Prevalence in adults (general population)
- 40–60: Peak age range (years old)
What triggers the freeze
Synovium thickens and inflames for unclear reasons.
Diabetics face triple the risk of frozen shoulder.
Pain before stiffness
Pain often precedes the loss of motion.
Why early treatment matters
Calming inflammation early may shorten the freeze.
Injection Administered
A needle delivers corticosteroid straight into the joint capsule.
- 40 mg: Typical dose (triamcinolone equiv.)
- <5 min: Procedure time (in-clinic injection)
- Ultrasound: Guidance method (improves accuracy)
- 22–25G: Needle gauge (posterior approach)
Reaching the joint space
Imaging guidance confirms placement inside the capsule.
Local versus systemic dosing
Intra-articular delivery concentrates the drug on-site.
Ultrasound guidance raises accurate placement above 90%.
Often paired with anesthetic
Lidocaine mixed in gives fast, short-lived pain relief.
Anti-Inflammatory Action
Steroid molecules shut down cytokine signaling in the synovium.
- IL-1, IL-6, TNF-α: Cytokines suppressed (key mediators)
- 24–72 h: Onset of action (molecular effect)
- Genomic: Mechanism class (gene transcription block)
- Glucocorticoid R: Receptor target (cytoplasmic receptor)
Genomic suppression pathway
Steroid-receptor complexes block inflammatory gene transcription.
One receptor complex can silence many cytokine genes.
Cellular calming
Fewer immune cells infiltrate the synovial lining.
Vascular effect
Reduced capillary leakiness lowers joint swelling.
Pain Reduction
Falling inflammation translates into measurable pain relief.
- ~50%: Pain drop by week 4 (average reported)
- +20–30%: ROM gain by week 6 (external rotation)
- ~70–80%: Responders (early-stage patients)
- Weeks 2–6: Best window (peak improvement)
A short lag before relief
Molecular effects take days to become noticeable.
Motion follows pain
Less pain lets patients move and stretch more.
Injection plus physical therapy outperforms either alone.
A plateau eventually appears
Improvement curves flatten after several weeks.
Limited Duration Effect
Relief is substantial but capsular fibrosis remains largely untouched.
- 6–12 wk: Relief duration (typical benefit window)
- ≤3 / yr: Repeat injections (to limit tissue harm)
- Minimal: Fibrosis reversal (steroid alone)
- ~30–35%: Late-stage ROM cap (if capsule thickened)
Inflammation is not fibrosis
Steroid quiets swelling, not scarred collagen.
Thickened capsule tissue needs stretching or release, not steroid.
Why late-stage responds less
Fibrotic capsules limit how far motion can improve.
What comes after
Physical therapy or capsule release often follows.