Important points: 1-Extensor tendon subluxation or dislocation can trigger other tendons dislocation or subluxation, 2-The head of metacarpal bones will migrate dorsally==> flexion deformity, 3-Ulnar dislocation of the extensor tendon==> adduction at MCP J==> ULNAR DEVIATION, 4-Lack of MCPJ Extension ==> over-activity of interensic muscles of hand==> hyper-extension of PIP joints==> swan neck deformity, 5- Abnormal Biomechanics==> deformity despite control of RhA activity by medicines, 6-When you do MSK US assessment of RhA patient, don't forget to do dynamic scan, 7- Abnormal biomechanics due to inflammatory attenuation of ligaments==> red flag of future damage.

3. *Female *26years
* Rheumatoid Arthritis (RF-/ACPA+)
*TTT; Oral steroids (5mg/d), Leflunomide
(20mg/d),

4. Pain at Left 3rd MCP J + audible snap with
extension after maximal flexion of fingers

5. Ultrasound study

6. Static scan

7. R = Radial
U = Ulnar
LT = Left
= Extensor
tendon
= ?

8. Dynamic scan

9. Diagnosis

10. Snapping extensor tendon of Left
middle finger due to attenuation
of the radial sagittal band at 3rd
MCPJ (Type ।।। closed injury) }

11. Discussion

12. Anatomy

15. sono-Anatomy

17. Normal versus attenuation

19. Attenuation versus Tear

21. Epidemiology

22. *Middle Finger
*Sagittal Band
- Radial : ulnar = 9 : 1

23. Mechanism of injury

26. Rayan and Murray
Classification of Closed
Sagittal Band Injury

28. Complications

30. TTT

31. Control of RhA activity
(10 mg steroids + MTX 12.5mg/week +
hydroxychloroquine 200mg twice daily) +
dynamic MCP extension
assist splint

33.  surgical repair.

35. May the Force be with you"