Extensor Tendon Anatomy, Common Injury and Treatment Christina Schmidt, OTR/L, CHT University of California, Irvine Irvine, CA February 9-11, 2018 2 How Extensor Tendons Differ from Flexor Tendons Dorsum of hand revealing extensor tendons of Zones 5-7 Anatomy more complex Tendons are flatter, more superficial, largely extrasynovial Can rapidly adhere to underlying bones and joints Often heal with a lag secondary to longer excursion pull Weaker than digital flexors Muscle/Tendon Functions Wrist extension: RN 1. Extensor Carpi Radialis Longus 2. Extensor Carpi Radialis Brevis 3. Extensor Carpi Ulnaris (PIN) 3 4 Muscle/Tendon Functions MP Extension: RN Extensor Digitorium Communis (PIN) Extensor Indicis Proprius (PIN) Extensor Digiti Quinti Minimi (PIN) Muscle/Tendon Functions PIP extension: UN, MN, RN Interossei: UN Lumbricals: MN & UN ED, EIP, EDM: RN DIP extension: RN DIP extension is the combined action of ED, lateral bands, and tenodesis effect of spiral oblique retinacular ligament The terminal extensor tendon serves to extend the DIP joint in synchrony with the PIP joint 5 6
Muscle/Tendon Functions: Thumb Thumb CMC extension/abduction: RN 3. Abductor Pollicis Longus (PIN) 4. Extensor Pollicis Brevis (PIN) 5. Extensor Pollicis Longus (PIN) Abductor Pollicis Brevis (Median N) Thumb MP extension: Extensor Pollicis Brevis Thumb IP extension: Extensor Pollicis Longus Extensor Tendon Healing Vascular mesenteries, called mesotendons, (similar to the vinculae in flexor tendons) carry blood to the extensor tendons from branches of the radial and ulnar arteries and vessels of the deep palmar arch. Synovial fluid also provides nutrition to the extensor tendons, especially under the extensor retinaculum. 7 8 Digital Extension Digital Extension The extensor mechanism is comprised of both extrinsic and intrinsic systems. The extrinsic system is radial nerve innervated. The intrinsics are median and ulnar nerve innervated. The precise length relationships between the central slip, lateral band, terminal tendon, and the interweaving of fibers make restoration of extension difficult. ED Central Slip Lateral Bands Terminal Extensor Tendon Lumbrical Action Interossei Action 9 10 Supporting Ligaments: ORL Oblique retinacular ligament (ORL) Origin: on the flexor tendon sheath at P1 Insertion: dorsally on P3, lateral to the terminal extensor tendon Taut w/pip extension Assists the initial motion of DIP extension TL ORL TRL Supporting Ligaments Transverse retinacular ligament extends from the lateral bands to the flexor tendon pulley, encompassing the PIP laterally. It prevents dorsal displacement of the lateral bands and provides additional stability to the PIP joint. Supporting structure to central slip 11 12
Supporting Ligaments Lumbrical Action Triangular ligament is located over the dorsum of the middle phalanx, and serves to support the lateral bands in place dorsally, preventing volar displacement. It connects the converging lateral bands over the dorsal middle phalanx. Supporting structure to terminal tendon Extend the IP joints and simultaneously flex MCPs of the 2-5 th digits Extend IP joints when MCPs are flexed due to their insertion into extensor expansion 13 14 Interossei Action Dorsal Interossei: Abduct I, M, R Assist in flexion of MCP joints and extension of IPs Palmar Interossei: Adduct I, R, S Assist in flexion of MCP joints and extension of IPs DAB PAD Extensor Tendon Zones: Digits Zone 1: DIP joint Zone 2: Middle phalanx Zone 3: PIP joint Zone 4: Proximal phalanx Zone 5: MPs Zone 6: The dorsal hand, distal to the extensor retinaculum Zone 7: Extensor retinaculum Zone 8: Proximal to the retinaculum Zone 9: Intramuscular portion of tendon Zone 10: Forearm muscle bellies 15 16 Extensor Tendon Zones: Thumb Zone T1: IP joint Zone T2: Middle phalanx Zone T3: MP joint Zone T4: 1st metacarpal Zone T5: Carpus ZONES 1 & 2 17 18
Pathoanatomy Closed rupture or laceration of terminal extensor tendon over DIP Mallet, cricket, baseball finger, drop finger Unable to actively extend DIP joint, but passively correctable when acute. Most common cause is sudden flexion force to extended finger but can be a trivial incident. Mallet Finger Mallet Fracture Classification I: Closed w/ or w/o bony avulsion II: Direct laceration at DIP (open) III: Trauma w/loss of skin, tendon, bone IV: Significant dorsal lip fracture 19 20 Mallet Fracture (Avulsion) Nonoperative Management Continuous DIP splinting 6-8 weeks in slight hyperextension Alumafoam Stack splint Thermoplastic splint Bony mallet: DIP 0 PIP should not be immobilized in splint Weaning schedule 21 22 Mallet Finger/Swan Neck Deformity Sequence of a Swan neck deformity due to distal tendon rupture. Extensor tendon slides proximally due to loss of the distal insertion. Slack on the ORL and lateral bands allows them to displace dorsally into PIP hyperextension. DIP continues to flex further due to increased difficulty flexing the PIP joint. PIP hyperextension with DIP flexion 23 If Swan Neck Deformity Develops Utilize a swan neck splint that limits PIP full extension by 10-15 Can be used concurrently with DIP splint if PIP hyperextension is noted Prevents lateral bands from tightening dorsal to the axis of motion and helps the extension force to go distally to the DIP joint Combination figure 8 splint with mallet splint 24
Operative Management Used with more complex injuries Open injury Bony fracture fragment >30% of articular surface II-IV on classification scale Usually undergoes direct repair of tendon. Pinned in 0 extension following repair Therapy Post Surgery The physician will determine the appropriate time to begin motion. Pinned and splinted for the first 5-6 weeks. Motion is initiated gently when the pin is removed. Progressive flexion of 5 /week while maintaining full active extension DIP extension splinting between exercises and during heavier activities continues for 3-6 weeks following initiation of motion. 25 26 Therapy for Chronic, Untreated Mallet Fingers Regain full passive DIP extension Serial static splinting/casting Splint finger in continuous extension for 8 weeks Follow weaning protocol If unsuccessful, surgery or pinning may be indicated Surgical Options for Chronic Deformity Abbreviato procedure ORL reconstruction Fowler Tenotomy DIP fusion 27 28 Origins of Boutonniere and Swan Neck Deformities ZONES 3 & 4 Boutonniere: a flower worn in a button hole (P1 button holes up through central slip defect) Swan neck: looks like a swan s neck 29 30
Boutonniere Deformity Boutonniere: Closed Injury Sequence of a Boutonniere deformity: 1. Central slip ruptures 2. Head of P1 button holes through central slip defect 3. Lateral bands move more volarly, laterally, increasing their flexion force 4. Increased tension in lateral bands causes increased extension force at DIP, causing hyperextension Passively the PIP joint can be extended, but actively, it is unable to extend. The deformity may take place gradually over the course of several weeks. PIP flexion with DIP hyperextension 31 32 Boutonniere: Open Injury Open laceration over PIP joint/proximal phalanx may include injury to any combination of: Central slip Lateral bands Oblique fibers of the dorsal hood Transverse retinacular ligament Splinting for Boutonniere Deformity Safety Pin Splint Serial Casting 33 PIP Extension Splint 34 Fixed Boutonniere Versus PIP Flexion Contracture Swan Neck Deformity In a PIP flexion contracture (pseudoboutonniere), the DIP joint remains passively flexible. In a true boutonniere deformity, the DIP joint cannot be passively flexed due to oblique retinacular ligament (ORL) tightness Can test for ORL tightness Postural collapse deformity Can begin at MP, PIP, or DIP joints PIP hyperextension with DIP flexion 35 36
Swan Neck Deformity Splinting for Swan Neck Deformity Thermoplastic Figure 8 Four possible causes: Terminal tendon rupture FDS rupture (loss of dynamic PIP stabilization) PIP hyperextension from lax volar capsule 2 to synovitis or rupture of volar plate Intrinsic tightness 2 to MP pathology 37 Oval 8 splint 38 Boutonniere Deformity of Thumb Swan Neck Deformity of the Thumb Pathology begins at MP joint Most common thumb deformity in RA Pathology begins with subluxation of 1 st CMC joint 39 40 Treatment of Closed Injury Boutonniere: Immobilization Acute/Subacute (1 8 Weeks) Flexible - treat as an acute closed injury PIP extension splinting for 8 weeks Allow full active DIP flexion!!! Open or closed with stiff joint Regain extension of PIP first, then initiate static splinting Chronic (More than 8 Weeks) Flexible PIP - longer immobilization Stiff PIP - first regain mobility, then begin the countdown 41 Treatment of Open Injury w/repair 42
Treatment Protocols Post Surgery Early Controlled Passive Mobilization Early Controlled Active Short Arc of Motion Early Controlled Passive Mobilization An outrigger splint supports the PIPJ at 0 with rubber band traction. Allows a controlled amount of flexion beginning a few days post surgery. 43 44 Early Controlled PROM Thomes: hand-based splint MP in flexion and the PIP supported in full extension with a dorsal outrigger. 30 PIP flexion, and added 10 per week for the next 3 weeks when the splint was discontinued. Walsh: hand-based splint MP in extension and PIP supported in full extension with a dorsal outrigger. PIP joint was allowed 30 flexion for the first 3 weeks, and then the splint was discontinued. Early Controlled Active Short Arc of Motion Volar Static Extension Splint Proposed by Rosalyn Evans, OTR, CHT Follows belief that 3-5 mm glide is necessary to prevent adhesions Zone III, IV protocol Volar static extension splint Two exercise splints 45 46 Evans Protocol/Template Splints Classification of Results 42% 65% 58% 35% Exercise Template 1: 30 PIP flexion, 20 DIP flexion Exercise Template 2: PIP 0, DIP free (if lateral bands repaired, then 30 only) 47 48
Chronic Boutonniere Treatment Achieve full passive PIP extension using dynamic, static-progressive, serialstatic splints or casts. Perform aggressive DIP flexion actively and passively with the PIP supported in full extension to stretch the ORL. Operative Management of Chronic Boutonniere Deformities A: Anatomic repair B: Reconstruction using lateral bands (Littler technique) C: Reconstruction using both lateral bands Terminal tendon tenotomy: resection of tendon distal to insertion of central slip 49 50 Treatment Considerations ZONES 5 & 6 Crush injuries Tendon excursion length Both wrist and digits must be splinted Proximity to retinaculum 51 52 Sagittal Band Rupture The sagittal bands prevent bowstringing of the ED during extension, centralize ED at midline during flexion Rupture is usually atraumatic, involving radial fibers Can cause ED to sublux ulnarly and can cause incomplete extension Sagittal Band Splinting Splint to immobilize a sagittal band rupture 53 54
Sagittal Band Repair Techniques Intertendinous Connections Juncturae Tendinum Proximal laceration Distal laceration EIP, EDM - may need to splint only involved finger 55 56 Intertendinous Connections Proximal: the injured finger as well as the the adjacent finger(s) should be supported in full extension to prevent the juncturae from placing tension on the portion of the tendon distal to the repair. Distal: flexion of the adjacent finger(s) will not adversely affect the repair, as the juncturae will pull the portion of the extensor tendon proximal to the repair more distally, taking tension off the repair. 57 Splint for a Distal Juncturae Laceration 58 Treatment Protocols Immobilization Protocol Four Protocols: Immobilization Controlled passive motion Controlled early active motion Immediate Controlled Active Motion: Zone 4-7 (ICAM, Relative Motion) Splint #1: Wrist 40-45 ext, MPs & IPs 0 ext, full time for 3 weeks Splint. #2: wrist 40-45 ext, MPs 0 ext, IPs free in daytime for weeks 3 to 6. Wear splint #1 at night Splint #1 59 Splint #2 60
Early Passive Motion (Reverse Kleinert) Initiate therapy 24 hours to 3 days postop Splint for 6 weeks Wrist 40-45 ext MPs, IPs in dynamic ext slings resting at 0 ext Volar flexion block to allow 30 flex in I & M, 40 in R & Controlled Early Active Motion Splint position Wrist held in 20 ext, MPs/IPs at 0 MP moves actively from 30 flex to 0 ext MP increases weekly to 45, 60, 90 flexion Can be combined with early passive motion protocol Based on minimal active tension, place/hold concept, and tenodesis L 61 62 Zones 4-7 Immediate Controlled Active Motion (ICAM, Wyndell Merritt Method) Forearm-based wrist splint with a yoke orthosis with the involved MP in 15-20 greater extension relative to uninvolved joints. Reduces extended position of the wrist to enhance tendon excursion and glide zone IV-VII repairs. Relative Motion Splint Program Protocol (0-21 days) Wrist and yoke orthoses are used continuously Active digit flexion/ extension are permitted, limited only by the relative extension of the affected digit Full digit flexion and extension must be achieved before progressing to phase 2 Phase 2 (22-35 days) Yoke orthosis is worn continuously but wrist orthosis is removed for wrist AROM If there is no lag, composite wrist and digit ROM is initiated When wrist AROM is normal, wrist orthosis is d/c for light duty use Relative Motion Splint Program Phase 3 (36-49 days) Wrist orthosis is d/c Yoke orthosis is removed for digit ROM only and d/c when digit ROM is normal ZONES 7 & 8 66
I know these 6 dorsal compartments like I know the back of my hand! Zone 7 - Compartments of the Extensor Retinaculum Area through which the extensors gain entrance to the hand. Compartment 1: APL & EPB Compartment 2: ECRL & ECRB Compartment 3: EPL Compartment 4: EDC & EIP Compartment 5: EDM Compartment 6: ECU Extensor retinaculum is a wide fibrous band that prevents bowstringing of the tendons across the wrist joint. Remember: 22, 12, 11 67 68 Zone 7: Wrist Extensor Tendon Lacerations Tendons are synovial at this point Adhesions similar to Zone 2 flexor tendon injuries Splint need not include IP joints Vaughn-Jackson Lesion Tendon rupture of ED to 4 th & 5 th fingers at ulnar styloid Often seen in RA Will require surgery Tendon repair vs. transfer Wrist in 40 extension for 4 weeks. Fingers free if no digital extensors are injured. Multiple repairs need differential tendon gliding. 69 70 Zone 8: Dorsal Forearm, Proximal to Extensor Retinaculum Splint as in Zone 7 Extrinsic extensor tendon tightness is a common problem, frequently requiring later splinting to regain composite wrist and MP flexion. ZONES 9 & 10 71 72
Zones 9 & 10 Splint wrist only Differential tendon gliding necessary THUMB ZONES T1-T5 73 74 Thumb Extensor Tendons Treatment Considerations Zones T-1 & T-2: similar to finger treatment Zones T-3 & T-4: watch for MP extension contracture Zone T-5: prone to adhesions at wrist; consider controlled early passive motion, controlled active motion or combination of both Thumb Extensor Tendon Injuries Zone T-1 IP extension splinting and/or pinning in full extension Splint for 8 weeks followed by gradual increase of flexion while maintaining full active IP extension. Zone T-2 Hand-based splint should immobilize MP and IP joints at 0, with radial extension of the CMC joint 75 76 Thumb Extensor Tendon Injuries Zones T-3 & T-4 Splint should include the wrist at 30-40 extension, with MP and IP supported at 0, slight CMC abduction Zone T-5: Conservative Treatment Begin gentle motion at 3-4 weeks for conservative treatment. Dense adhesions form to the thumb extensors. Tendon at this level is synovial 77 78
Early Controlled Passive/Active Motion Protocol: Thumb T5 Thumb T5: Early Controlled Passive/Active Motion Thumb IP will need 60 of flexion to achieve 5mm of tendon gliding with wrist in neutral & MP at 0 Reverse Kleinert for Thumb 0-3 weeks Dynamic extension splint with wrist in 30-40 extension and MP at 0 A volar block allows 60 of IP flexion with sling returning the IP to 0 between reps and at rest 3 weeks Remove volar block to allow IP flexion as tolerated Add active thumb IP extension 4-5 weeks Continue dynamic splinting at home In therapy, begin gentle composite flexion/extension of thumb 6 weeks (d/c dynamic extension splint Begin PROM to thumb as needed If extensor lag is present, add night extension splinting 79 80 THANK YOU! References 1. An K N, Ueba Y, Chao EY, et al.: Tendon excursion and moment arm of index finger muscles. J Biomech. 16:419 425 1983 2. Brand PW, Beach RB, Thompson DE: Relative tension and potential excursion of muscles in the forearm and hand. J Hand Surg. 6:209 219 1981 3. Doyle JR: Extensor tendons: acute injuries. Green DP Operative Hand Surgery. 3rd ed 1993 Churchill Livingstone New York 1931 1933 4. Evans RB: Therapeutic management of extensor tendon injuries. Hand Clin. 2:157 169 1986 5. Evans RB: Early active short arc motion for the repaired central slip. J Hand Surg. 19A:991 997 1994 6. Evans RB, Thompson DE: An analysis of factors that support early active short arc motion of the repaired central slip. J Hand Ther. 5:187 201 1992 7. Hanz KR, Saint Cyr M, Semmler MJ, et al.: Extensor tendon injuries: acute management and secondary reconstruction. Plast Reconstruct Surg. 121 (3):109e 120e 2008 Mar 8. Howell JW, Merritt WH, Robinson SJ: Immediate controlled active motion following zone 4 7 extensor tendon repair. J Hand Ther. 2005 182 190 9. Howell JW. Immediate controlled active motion following zone 4 7 extensor tendon repair. American Society of Hand Therapists Annual Meeting, Orlando, Fla., September 1999 10. Hung LK, Chan A, Chang J, et al.: Early controlled active mobilization with dynamic splintage for treatment of extensor tendon injuries. J Hand Surg. 5A:251 257 1990 11. Kaplan EB: Anatomy, injuries and treatment of the extensor apparatus of the hand and the digits. Clin Orthop Relat Res. 13:24 41 1959 12. Ketchum LD, Brand PW, Thompson D, Pocock GS: The determination of moments for extension of the wrist generated by muscles of the forearm. J Hand Surg. 3:205 210 1978 81 82 References Con t 13. Kleinert HE, Verdan C: Report of the committee on tendon injuries. J Hand Surg. 8A (5 Part 2):794 798 1983 14. Newport ML, Blair WF, Steyers CM: Long term results of extensor tendon repair. J Hand Surg. 15A:961 966 1990 15. Purcell T, Eadie PA, Murugan S, et al.: Static splinting of extensor tendon repair. J Hand Surg. 25B:180 182 2000 16. Rayan GM, Mullins PT: Skin necrosis complicating mallet finger splinting and vascularity of the distal interphalangeal joint overlying skin. J Hand Surg. 12A:548 552 1987 17. Schneider LH, Smith KL: Boutonnière deformity. Hunter JM Schneider LH Mackin EJ Tendon Surgery in the Hand. 1987 Mosby St Louis 349 357 18. Scweitzer TP, Rayan GM: The terminal tendon of the digital extensor mechanism: Part I, anatomic study. J Hand Surg. 29A:898 902 2004 19. Sharma JV, Liang NJ, Owen JR, et al.: Analysis of relative motion splint in the treatment of zone VI extensor tendon injuries. J Hand Surg. 31A (7):1118 1122 2006 20. Skirven,Osterman,Fedorczyk,Amadio : Rehabilitation of the Hand and Upper Extremity. Sixth Edition.2011 21. Taleisnik J, Gelberman RH, Miller BW, Szabo RM: The extensor retinaculum of the wrist. J Hand Surg. 9A:495 501 1984 22. Wilson RL, Fleming F: Treatment of acute extensor tendon injuries. Hunter JM Schneider LH Mackin EJ Tendon and Nerve Surgery in the Hand: A Third Decade. 1997 Mosby St Louis 567 576 23. Zancolli EA: Structural and Dynamic Basis of Hand Surgery. 2nd ed 1979 JB Lippincott Philadelphia 15 23, 47 53 24. Zbrodowski A, Gajisin S, Grodecki J: Vascularization of the tendons of the extensor pollicis longus, extensor carpi radialis longus and extensor carpi radialis brevis muscles. J Anat. 135:235 244 1982 83