Flexor Tendon Injury ER/VC

Classification Distal to FDS insertion FDS insertion to distal palmar crease Palm Carpal tunnel Wrist to forearm

Physical exam Inspection observe resting posture of the hand and assess the digital cascade evidence of malalignment or malrotation

Range of motion passive wrist flexion and extension ---> tenodesis effect active PIP and DIP flexion for each digit

FDPFDS

Treatment Nonoperative wound care and early range of motion – indications partial lacerations < 60% of tendon width Operative flexor tendon repair and controlled mobilization – indications lacerations > 60% of tendon width

Flexor Tendon Repair of Complete Lacerations Core suture Epitendinous suture

Incision incisions should always cross flexion creases transversely or obliquely

Postoperative Rehabilitation Immobilize Active and passive exercises under supervision Duran or Kleinert dynamic mobilization

Duran protocol low force and low excursion active finger extension with patient-assisted passive finger flexion

At surgery, a dorsal extension-block splint is applied with the wrist at 20-30° of flexion, the MCP joints at 50-60° of flexion, and the IP joints straight

Kleinert protocol low force and low excursion active finger extension, dynamic splint- assisted passive finger flexion

Combines dorsal extension block with rubber-band traction proximal to wrist Originally, included a nylon loop placed thru the nail, and around the nail is placed a rubber band This passively flexes fingers, & the patient actively extends within the limits of the splint

Complications Tendon adhesions Rerupture – 15-25% rerupture rate Joint contracture – rates as high as 17% Swan-neck deformity Trigger finger Lumbrical plus finger Quadrigia

Question 1 A 28-year-old man sustained a complete laceration of the flexor digitorum profundus of his index finger while cutting a watermelon 3 days ago. A clinical photograph is shown in Figure A. The surgeon plans to repair the tendon using a 4-strand core suture technique. Which method of tendon repair will give him the best results in terms of load to failure and gliding resistance?

PREFERRED RESPONSE 5 Repair with core suture purchase 10mm from the cut edge, coupled with circumferential simple running epitendinous suture will give him the best load to failure and gliding resistance. The strength of tendon repairs depend on the number of strands crossing the repair site. Ideally, repairs should have 4-6 strands to allow for early active motion. A running epitendinous suture is recommended to improve tendon gliding and repair strength. Gulihar et al. compared 3 different epitendinous suture techniques. They found that compared with an intact tendon, gliding resistance increased 100% with the Halsted repair, 80% with the Silfverskiold repair and 60% with a running suture. They thus recommend a simple running suture when an epitendinous suture is needed. Lee et al. compared core suture purchase at 3, 5, 7 and 10mm from the cut edge. The 10mm-repair group had the highest 2-mm gap force and ultimate failure load. They recommend 10-mm suture purchase for optimal performance and to allow early active motion. Figure A shows a laceration to the volar aspect of the index finger in flexor zone II. Illustration A shows a core suture purchase distance from the cut edge (represented by "X", where 10mm is the ideal distance). Illustration B shows 3 different epitendinous suture techniques (A, simple running; B, Silfverskiold; C, Halsted). Incorrect Answers: Answers 1, 3: Suture purchase 5mm from the cut edge is inferior to purchase at 10mm from the cut edge. Answer 2: An epitendinous suture adds to repair strength and improves gliding compared with no epitendinous suture. Answer 4: The Silfverskiold technique has increased gliding resistance compared with a simple running suture.

Question 2 Which of the following statements is true regarding zone II flexor tendon injuries? 1. At this level, FDS and FDP are located within separate tendon sheaths 2. FDS repair has not been shown to improve outcomes 3. Improved gliding is seen with repair of 1 slip of FDS compared to repairing both slips 4. Repairing FDS does not affect post-operative digit strength 5. FDP repair has not been shown to improve outcomes

PREFERRED RESPONSE 3 In zone II flexor tendon injuries, repairing only one slip of FDS has been shown to improve gliding when compared to repair of both slips. Zone II flexor tendon injuries have notoriously had poor outcomes secondary to high rates of adhesion formation at the pulleys. However, new advances in post-operative rehabilitation have significantly improved outcomes to the point where it is no longer considered "no man's land." Management of the FDS has been a source of controversy. In the past, the FDS was occasionally excised to theoretically make more room for the FDP. This has now been largely abandoned and the FDS is repaired whenever possible. Whether or not to repair both slips of FDS remains controversial, with in vitro data suggesting that gliding resistance is improved if only one slip is repaired.

Question 3 Pediatric flexor tendon injuries of the upper extremity differ from adult flexor tendon injuries in which of the following ways? 1. Delayed presentation is not common. 2. A staged repair is never necessary. 3. Six to eight weeks of postoperative immobilization is recommended. 4. Cooperation with occupational therapy can be difficult. 5. The use of Botulinum is contraindicated.

PREFERRED RESPONSE 4 Pediatric flexor tendon injuries have several remarkable distinctions from those in adults. Delayed presentation is more common in children, at times requiring staged flexor tendon reconstruction. Three to four weeks of postoperative immobilization following acute repair is recommended in children as opposed to early motion protocols used in adults. Temporary paralytic agents (botulinum toxin type A) have also been shown to facilitate the rehabilitation phase of flexor tendon care in very young children.

Question 4 A 24-year-old male cuts his left middle finger with a knife while chopping vegetables. Physical exam reveals a zone 2 flexor tendon laceration. He undergoes a 2-strand core suture repair with epitendinous suture. This particular repair is strong enough for each of the following rehabilitation protocols EXCEPT 1. Kleinert protocol 2. Duran protocol 3. Synergistic motion protocol 4. Low force and low tendon excursion passive range of motion 5. Early digit active range of motion protocol

PREFERRED RESPONSE 5 Early active range of motion protocols are thought to decrease adhesions but risk rerupture or gap formation. Strickland et al notes that the generation of muscle forces to either assist digit flexion or perform “place and hold” exercises require at least a 4-strand core suture with epitendinous repair. This patient only had a 2-strand repair. The Kleinert and Duran protocols are both forms of low force and low tendon excursion programs, that include passive digit flexion range of motion. Kleinert includes a dorsal block splint with the wrist in 45° of flexion and elastic bands secured to the patient’s nails and a more proximal attachment point. Once the interphalangeal joints are actively fully extended, recoil of the elastic bands flexes them down passively. The Duran protocol utilizes the other hand to passively flex the affected DIP and PIP joints and a higher amount of patient compliance is needed. Synergistic motion regimens allow passive digit flexion combined with active wrist extension, followed by active digit extension coupled with active wrist flexion to produce low forces and high tendon excursions at the involved digit.

Question 5 You are seeing a 26-year-old man after he was involved in a knife fight. He has pain when flexing and extending his index finger. You explore a 2 centimeter wound in zone 2 and find his flexor tendons to the index are 40% lacerated. What is the preferred method of treatment? 1. Trim the frayed tendon edges and begin early range of motion 2. Trim the frayed tendon edges and cast in an intrinsic positive position for 2 weeks 3. Peritendinous 6/0 and Core 4/0 suture repair 4. Core 4/0 suture repair 5. Core 6/0 suture repair

This patient has a partial flexor tendon laceration involving < 60% of the width of the tendon, therefore, the preferred management would be to trim the frayed tendon edges and begin early range of motion. Flexor tendon injuries are classified into five anatomic zones. Injuries in zone II, which ends at the insertion of the FDS tendon at the middle phalanx, are particularly challenging because the tendon gliding must be restored within a tight fibro-osseous sheath while minimizing the formation of adhesions in surrounding tissues. Bishop et al. developed a nonweightbearing canine model to examine partial tendon lacerations and found early motion improved tendon excursion and stiffness, resulting in more normal tendon morphology. They concluded that partial tendon lacerations less than 60% cross-sectional area be treated without tenorrhaphy and with early mobilization. McGeorge et al. compared the results of repair versus non-repair in patients with zone II tendon lacerations and concluded that tendons lacerated by 60% or less should not be repaired.

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