1. Extensor Tendon Injuries
James Ledgard
Royal North Shore Hospital and Lismore
Registrar Teaching 11th April 2017

2. Foundation Skills for Surgical Educators
Adult learning
Interaction
Motivation
Feedback
Treat you as colleagues

3. Outline Anatomy Zones of injury Recognition and Treatment
Rehabilitation
Complications

4. Copy of Presentation

5. Extensor Compartments

6. Innervation Q

7. Innervation

8. Innervation

9. Typical Arrangement Q
The typical arrangement of finger extensor tendons is as follows: (1) single EIP inserting ulnar to the EDC tendon of the index finger; (2) single tendon from the EDC to the index and middle fingers; (3) double tendon from the EDC to the ring finger; (4) absent EDC to small finger, but usually a substantial junctura tendinum from the ring EDC to EDM; and (5) double EDM tendon to the little finger with a double insertion into the MP joint hood (see Figure 6.2).127

10. Extensor Apparatus

11. PLEASE WRITE IT IN YOUR OPERATION REPORTS
Zones of Injury
DIFFERENCES
Anatomy
Repair
Excursion
Rehab
Complications
PLEASE WRITE IT IN YOUR OPERATION REPORTS
Boyes10 suggested that the amplitude of tendon excursion for the wrist extensors is 3.3 cm, and the amplitude of tendon excursion for the finger extensors and EPL is 5 cm; however, most of this excursion occurs over the forearm, wrist, and dorsal hand. The amplitude of tendon excursion over the dorsum of the finger is extremely small; this explains why small tendon gaps, overtightening of tendon repairs, or small amounts of bony shortening or angulation can lead to dra- matic extensor lags or restriction of flexion at the PIP and DIP joints.
Vahey and associates125 found an experimental 12-degree PIP joint extensor lag was produced with every 1 mm of tendon lengthening over the proximal phalanx. Schweitzer and Rayan104 showed that 1 mm of terminal tendon lengthening resulted in a 25-degree DIP joint exten- sor lag, and that 1 mm of terminal tendon shortening severely restricted DIP joint flexion.
Over the dorsum of the hand, it has been shown experimentally that relative lengthening of the extensor tendon by 2 mm produces an extensor lag of approximately 7 degrees at the MP joint. Because most MP joints had a “reserve” of hyperextension ability of about 35 degrees, however, 5 to 6 mm of relative extensor tendon lengthening in this zone may not produce a clinically relevant lack of extension.118

12. Zone 1 - Mallet
Acute or Chronic
Soft Tissue or Bony
Closed or Open

13. Mallet Splint 8 weeks then wean
Soft Tissue Mallet
Unlikey to sustain a closed mallet injury if your PIPJ is flexed.
Mallet Splint 8 weeks then wean

14. Bony Mallet X-Ray CONSIDER Fragment size Volar subluxation
Only indication for surgery

15. Zone 3 – Central Slip Acute or Chronic Soft Tissue or Bony
Closed or Open

16. Closed Central Slip
SUSPECT IN
Blunt PIPJ trauma
Volar Dislocation

17. Diagnosis Suspicion Tenodesis Weak extension Elson test Q X-Ray
Follow-up
Splint in extension 6 weeks then wean/dynamic another 6 weeks

18. Elson Test

19. Zone 4 and 5 Partial Flat vs Round Avoid bunching Complex injury
Rehab controversial
Assess tension intra-operatively

20. Zone 6 Round Juncturae Tendinae Corset Technique Stiffer Quicker
Less shortening
In 1997, Howard and colleagues45 compared the MGH, modified Bunnell, and modified Krackow-Thomas repairs in cadaveric zone 6 extensor tendon lacerations, and found the MGH technique to be superior. In a 2005 study of zone 4 extensor tendon repairs with 4-0 nonabsorbable, braided polyester (Ticron) suture, Woo and coworkers133 found the modified Becker technique to be the strongest repair, with a significantly greater resistance to 1- and 2-mm gap and the greatest ultimate strength. Lee62 com- pared the augmented Becker, the modified Bunnell, and a new, running interlocking horizontal mattress technique and found the newer technique to be stiffer, to produce less shortening, and to be more rapid than the other techniques, without a significant difference in the ultimate load to failure. This newer technique, termed the corset suture, does not require the placement of core sutures (Figure 6.10).
Lee SK, Dubey A, Kim BH, et al: A biomechanical study of extensor
tendon repair methods: introduction to the running-interlocking horizontal mattress extensor tendon repair, J Hand Surg [Am] 35:19- 23, 2010.

21. Zone 7
Care with releasing compartments 4 and 6

22. Rehabilitation – Open Repairs
Zone 1 – 2
Mallet splint weeks
Zone 3
Extension splint 6 weeks
Zone 4 – 5
30/30/0/0 splint 4 weeks
Zone 6 – 8
30/30 splint 4 weeks

23. Outcomes with Static Splinting
64% good or excellent Simple injury
45% Complex injury
Flexion loss greater Extension loss
Zones worse Zones 5 - 8
Miller’s Outcome Classification System 1942
In 1990, Newport79 reported on the long-term results of extensor tendon repair treated with static splinting. Of patients without associated injury, 64% achieved good or excellent results, whereas only 45% of patients with associated injuries achieved good or excellent results. More fingers lost the ability to flex fully than lost the ability to extend. Injuries in zones 1 through 4 had a worse outcome than injuries in the more proximal zones.
Newport ML, Blair WF, Steyers CM Jr: Long-term results of extensor tendon repair, J Hand Surg [Am] 15: , 1990.

24. Rehabilitation – Open Repairs
ALTERATIONS
Partial injury
Good repair
Good therapist
Motivated patient
Complex injury
CONSIDER
Passive protocol
Dynamic splint + Controlled flexion
Active protocol
Controlled flexion

25. Complications
Extension Lag
Poor Flexion
Swan Neck
Boutonniere

26. Swan Neck Deformity

27. Boutonniere Deformity Q
What causes a Boutonniere deformity?

28. Boutonniere Deformity Q

29. Summary Anatomy is key Zone of injury is important so record it
Repair
Rehab
Complications
Prevention of complications through good management is better than cure

30. Foundation Skills for Surgical Educators
The session key is:

31. Q 1. Why can this man with a nerve injury extend his wrist?

32. Q 1. Why can this man with a nerve injury extend his wrist?
ECRB is innervated by the radial nerve.
The radial nerve is spared.
He has a partial radial nerve injury.

33. Q 1. Why can this man with a nerve injury extend his wrist?
ECRB is innervated by the radial nerve.
The radial nerve is spared. ✔
He has a partial radial nerve injury.

34. Q 2. Why are you able to extend your IF and LF independently?
The typical arrangement of finger extensor tendons is as follows: (1) single EIP inserting ulnar to the EDC tendon of the index finger; (2) single tendon from the EDC to the index and middle fingers; (3) double tendon from the EDC to the ring finger; (4) absent EDC to small finger, but usually a substantial junctura tendinum from the ring EDC to EDM; and (5) double EDM tendon to the little finger with a double insertion into the MP joint hood (see Figure 6.2).127

35. Q 2. Why are you able to extend your IF and LF independently?
They are innervated by a different nerve.
Each has an independent musculotendinous unit.
There is a separate tendon from EDC to both.
The typical arrangement of finger extensor tendons is as follows: (1) single EIP inserting ulnar to the EDC tendon of the index finger; (2) single tendon from the EDC to the index and middle fingers; (3) double tendon from the EDC to the ring finger; (4) absent EDC to small finger, but usually a substantial junctura tendinum from the ring EDC to EDM; and (5) double EDM tendon to the little finger with a double insertion into the MP joint hood (see Figure 6.2).127

36. Q 2. Why are you able to extend your IF and LF independently?
They are innervated by a different nerve.
Each has an independent musculotendinous unit. ✔
There is a separate tendon from EDC to both.
The typical arrangement of finger extensor tendons is as follows: (1) single EIP inserting ulnar to the EDC tendon of the index finger; (2) single tendon from the EDC to the index and middle fingers; (3) double tendon from the EDC to the ring finger; (4) absent EDC to small finger, but usually a substantial junctura tendinum from the ring EDC to EDM; and (5) double EDM tendon to the little finger with a double insertion into the MP joint hood (see Figure 6.2).127

37. Q 3. Why is the DIPJ not floppy when the Elson Test is positive?

38. Q 3. Why is the DIPJ not floppy when the Elson Test is positive?
Because the injured central slip extends the DIPJ.
Because the lateral bands tighten with flexion of the finger.
Because the injured central slip puts proximal tension on the lateral bands.

39. Q 3. Why is the DIPJ not floppy when the Elson Test is positive?
Because the injured central slip extends the DIPJ.
Because the lateral bands tighten with flexion of the finger.
Because the injured central slip puts proximal tension on the lateral bands. ✔

40. Q 4. What is the cause of a Boutonniere Deformity?

41. Q 4. What is the cause of a Boutonniere Deformity?
Central slip failure.
There are multiple causes for a Boutonniere Deformity.
Lateral bands translate volar to the axis of rotation of the PIPJ.

42. Q 4. What is the cause of a Boutonniere Deformity?
Central slip failure. ✔
There are multiple causes for a Boutonniere Deformity.
Lateral bands translate volar to the axis of rotation of the PIPJ.

43. Presentation available at
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