FLEXOR TENDON INJURIES OF THE HAND Michael Zlowodzki MD PGY-3 Resident University of Minnesota Department of Orthopaedic Surgery

OUTLINE Anatomy Clinical assessment Treatment depending on Zone of injury Tendon healing biology Repair techniques Post-op motion protocols Delayed grafting

ANATOMY

FDS ACT INDEPENDANTLY Origin (2 muscle bellies) Medial epicondyle Radial shaft Tendons arise from separate muscle bundles ACT INDEPENDANTLY

FDP SIMULTANEOUS FLEXION OF MULTIPLE DIGITS Origin: ulna & interosseous membrane FDP: Common muscle origin for several tendons SIMULTANEOUS FLEXION OF MULTIPLE DIGITS

FDP

FDS FDP FPL Lumbricals origin from radial side of FDP

CAMPER’s CHIASMA FDS divides and passes around the FDP tendon, the two portions of the FDS reunite at “Camper’s Chiasma”

TENDON SHEETS

PULLEYS Preserve A2 and A4 pulley to prevent bowstringing. NOTE: There is a mistake in this diagram: The C1 pulley is DISTAL to the A2 pulley!

TENDON EXCURSION 9 cm of flexor tendon excursion with wrist and digital flexion only 2.5 cm of excursion is required for full digital flexion with the wrist stabilized in neutral position

TENDON EXCURSION MP motion = no flexor tendon excursion 1.5 mm of excursion per 10 degrees of joint motion for DIP (FDP) and PIP (FDS, FDP)

BLOOD SUPPLY Segmental branches of digital arteries which enter the tendon through: vincula osseous insertions Synovial fluid diffusion

VINCULAE

CLINICAL EXAM

FDS: Clinical Exam

TENODESIS EFFECT Passive extension of the wrist does not produce the normal “tenodesis” flexion of the fingers if flexors are injured

FDS: Clinical Exam

FDP: Clinical Exam

FDP RUPTURE No active DIP motion (present passive DIP motion)

ZONES

REPAIR ALL COMPLETE TEARS AT ALL LEVELS!

ZONE 1 INJURIES: Jersey Finger

JERSEY FINGER

JERSEY FINGER

LEDDY CLASSIFICATION REPAIR WITHIN 7-10 DAYS Type 1: Retraction into palm Type 2: Retraction to PIP level Type 3: Bony avulsion (tendon attached) Type 4: Bony avulsion (tendon attached not attached to bony fragment) REPAIR WITHIN 7-10 DAYS

TYPES OF REPAIR Direct repair: if laceration is more than 1 cm from FDP insertion Tendon advancement: if the laceration is less then 1 cm from insertion.

TENDON ADVANCEMENT

BUTTON STRONGER THAN SUTURE ANCHORS

Tendon Advancement Previously advocated for zone 1 repairs, as moving the repair site out of the sheath was felt to decrease adhesion formation Disadvantages Shortening of flexor system Contracture Quadriga effect

QUADRIGA EFFECT If FDP tendon advanced too distally Entire muscle bells gets pulled distally Tendon excursion of FDP of other digits is limited Loss of grip strength

ZONE 2 INJURIES

ZONE 2 INJURIES Zone 2: Deep and superficial flexor gliding inside tendon sheets Traditionally “No man’s land”: Stiffness after repair

INJURY: Tendons retract

ZONE 2: PARTIAL LACERATIONS

Partial laceration No repair if 40% of the tendon intact Potential complications: Triggering Tendon entrapment Eval for the risk of triggering; debride if necessary dorsal block splinting for 6 to 8 weeks

Conservative treatment: N=15 patients with zone II partial flexor tendon lacerations of the width of the tendon (Avg. 71%) Conservative treatment: Dorsal blocking splint with wrist in 10° of flexion Immediate guarded active ROM Splint removed @ 4w No restriction @ 6w excellent results in 93% and good in 7%

Why not fix a partial laceration when you staring at it in the OR anyway? Because the dissection necessary to fix it might cause too much scarring, which might outweigh the benefit

ZONE 2: COMPLETE LACERATIONS

MORE STRANDS: STRONGER & STIFFER REPAIR

Ultimate Strength and Repair Technique Proportional to number of strands 6 and 8 strand repairs strongest Steep learning curve Increased bulk and resistance to glide Increased tendon handling and adhesion formation May not be necessary for forces of early active motion 4-STRAND REPAIR ADEQUATE STRENGTH WITHOUT COMPLEXITY OF 6-8 STRANDS

Proximal Tendon Retrieval

Fix FDP and FDS or just FDP? Why? Because the blood supply to the FDP tendon is jeopardized if the FDS is not also fixed (due to the vinculae anatomy) (Personal communication: Dr. James House)

COMPLICATIONS Stiffness Re-rupture Tenolysis may be required in an estimated 18% to 25% of patients No earlier than 3 months after repair If no ROM improvement for 1-2 months

ZONE 3 INJURIES

Lumbrical muscle bellies usually are not sutured because this can increase the tension of these muscles and result in a “lumbrical plus” finger (paradoxical proximal interphalangeal extension on attempted active finger flexion).

ZONE 4 INJURIES

ZONE 4: Carpal Tunnel

TENDON HEALING

Flexor tendon healing Intrinsic healing: occurs without direct blood flow to the tendon Extrinsic healing: occurs by proliferation of fibroblasts from the peripheral epitenon adhesions occur and limit tendon gliding

PHASES OF TENDON HEALING 1.Inflammatory (0-5 days) : strength of the repair is reliant on the strength of the suture itself 2.Fibroblastic (5-28 days) : or so-called collagen-producing phase 3.Remodelling (28 days - 4months) TENDON WEAKEST @ 10-14 DAYS

BRUNNER INCISION

SUTURE TECHNIQUES

Kessler

Modified Kessler (1 suture) Advantage: Only one node inside the repair site. Easier to use a monofilament suture like a 4.0 Proline to re-approximate tendon edges.

Kessler-Tajima (2 sutures)

SUTURE MATERIAL Non-absorbable Most authors prefer a synthetic braided 3.0 or 4.0 suture, usually of polyester material (Mersilene, Tycron, Tevdek) However, monofilament sutures like nylon and wire are also used (e.g. Proline) Additional running, circumferential 5-0 or 6-0 nylon is used often

IN: Interference with healing SUTURE KNOT LOCATION IN: Interference with healing OUT: Interference with tendon gliding

SUTURE KNOT LOCATION FEW STUDIES – NO CONSENSUS Knots outside superior in one in vitro study (Aoki) Statistically significant increase in tensile strength at 6 wks with knots inside technique in canine model (Pruitt) FEW STUDIES – NO CONSENSUS

SHEAT REPAIR NO CLEAR ADVANTAGE ESTABLISHED Advantages Disadvantages Barrier to extrinsic adhesion formation More rapid return of synovial nutrition Disadvantages Technically difficult Increased foreign material at repair site May narrow sheath and restrict glide NO CLEAR ADVANTAGE ESTABLISHED

POST-OP REHAB

HISTORICAL Bunnel (1918) Postoperative immobilization Active motion beginning at 3 wks postop. Suboptimal results by today’s standards Improved suture material/technique as well as postoperative rehabilitation protocols

STIFFNESS RUPTURE

Too much motion To little motion RUPTURE STIFFNES

POST-OP PROTOCOLS GOAL: FULL ACTIVE ROM @ 10-12 weeks Kleinert: Active extension, passive flexion by rubber bands Duran: Controlled Passive Motion Methods Strickland: Early active ROM GOAL: FULL ACTIVE ROM @ 10-12 weeks

Kleinert Protocol

Duran protocol

DURAN PROTOCOL Dorsal Splint in 20 deg wrist flexion No rubber bands Passive flexion Designed in response to notion 3-5mm of tendon gliding sufficient to prevent restrictive adhesions

Rehabilitation Strickland (1980s-1990s) Uses a 4 strand repair with epitendinous suture Dorsal blocking splint with wrist at 20 deg of flexion Supervised active ROM starts POD #3 Unsupervised AROM at 4 weeks Rarely used, because it requires a pretty extensive “bulky” repair to allow for early active ROM. A lot of surgeons thinks that too much suture material may be problematic for tendon healing

CHILDREN Usually not able to reliably participate in rehabilitation programs No benefit to early mobilization in patients under 16 years Immobilization >4 wks may lead to poorer outcomes Role for Botox?

DELAYED RECONSTRUCTION

Single Stage Tendon Grafting: Indications Segmental tendon loss Delay in definitive repair (>3-6 weeks) Need Full PROM Competent pulleys

Single Stage Tendon Grafting Zone 2 Injuries Graft donors Palmaris longus Plantaris Long toe extensors (FDS) (EIP) (EDM)

Two Stage Reconstruction Indications Extensive soft tissue scarring Crush injuries Associated fractures, nerve injuries Loss of significant portion of pulley system

Two Stage Reconstruction: Stage 1 Excision of tendon remnants Hunter rod then placed through pulley system and fixed distally Reconstruct pulleys as needed if implant bowstrings

Two Stage Reconstruction: Stage 2 Implant removal and tendon graft insertion FDS transfer from adjacent digit described Postop Early controlled motion x 3 wks, then slow progression to active motion

Two Stage Reconstruction Patient selection Motivated Absence of neurovascular injury Good passive joint motion Balance benefits of two additional procedures in an already traumatized digit with amputation/arthrodesis

COMPLICATIONS

COMPLICATIONS Joint contracture Adhesions Rupture Bowstringing Infection

MY PREFERENCE (Based on this review and the subsequent feedback)

MY PREFERENCE Fix FDS and FDP asap - ideally within 7 days of injury 3.0 Proline modified Kessler stitch (one node inside) If tendon is big enough use another 4.0 Proline modified Kessler stitch Additional 5.0 Proline running epitendinous suture Kleinert or Duran post-op protocol

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THANK YOU Special thanks to Daniel Marek MD for borrowing some of the slides