Indications for Primary Flexor Tendon Repair

Chapter 8 Indications for Primary Flexor Tendon Repair

Jin Bo Tang, MD

Outline

Injuries to the flexor tendons occur in the digits, palm, wrist, or distal and mid-forearm. Repairs of flexor tendons in the digital sheath area are technically demanding. When wound conditions are favorable, primary tendon repair is preferable in terms of ease. However, it is important that primary repairs be performed by experienced surgeons. Alternatively, a well-accepted strategy is to postpone the repair for a few days, or even 1 to 2 weeks, to the delayed primary stage, for an experienced surgeon to become available. Repairs during either the primary or delayed primary stage produce comparable clinical outcomes.

Primary and delayed primary flexor tendon repairs are indicated in clean-cut tendon injuries with limited damage to the peritendinous tissues or a wound that can be converted to a clean-cut wound. Neurovascular injury is not a contraindication to primary repairs. Loss of soft tissue coverage over the tendon or the presence of fractures is a borderline contraindication. Local defects in skin and subcutaneous tissues can be covered by flap transfer. A simple fracture limited to the phalangeal or metacarpal shaft can be securely fixed with screws or mini-plates and the tendons can be repaired.

Serious crush injuries, severe wound contamination, extensive loss of soft tissues, or extensive destruction of pulleys and tendon structures are contraindications to primary tendon repairs.

Injuries in the flexor tendons can occur in the digits, palm, wrist, or distal and mid-forearm. Tendon repairs in the digital sheath area are most technically demanding and controversial. The advent of primary flexor tendon repairs within the synovial sheath region should be credited to pioneers of nearly half a century ago, including Verdan ¹ and Kleinert and colleagues.^2,³ Prior to that time, over most of the previous half century, primary tendon repair was not advocated and surgeons were accustomed to removing the tendons entirely and grafting in new tendon.^4,⁵ The reports of Verdan and of Kleinert and his colleagues on primary flexor tendon repairs followed by early mobilization established that the lacerated digital flexor tendon can be treated by direct end-to-end repairs when wound conditions are favorable.¹^–³

Anatomical Divisions

By virtue of their anatomical features, the flexor tendons in the hand and forearm are divided into five zones, which delineates the fundamental nomenclature for flexor tendon anatomy and surgical repairs.^1,^3,⁶ In the 1990s, the most complex areas—the flexor tendons within the digital sheath—were subdivided by Moiemen and Elliot⁷ and by Tang.⁸ The zoning is described in Box 8-1, and its relation to the locations of pulleys is shown in Figures 8-1 and 8-2.

Box 8-1 Nomenclature for Flexor Tendon Anatomy in the Hand and Forearm

Zones of Finger Flexor Tendons (Verdan)

1	From the insertion of the FDS tendon the terminal insertion of the FDP tendon
2	From the proximal reflection of the digital synovial sheath to the FDS insertion
3	From the transverse carpal ligament to the digital synovial sheath
4	Area covered by the transverse carpal ligament
5	Proximal to the transverse carpal liagment

Zones of Thumb FPL Tendon

1	Distal to the IP joint
2	From the IP joint to the A1 pulley
3	The area of the thenar eminence

Zone 1 in Fingers (Moiemen and Elliot)

1A	The very distal FDP tendon (usually <1 cm)
1B	From zone 1A to distal margin of the A4 pulley
1C	The FDP tendon within the A4 pulley

Zone 2 in Fingers (Tang)

2A	The area of the FDS tendon insertion
2B	From the proximal margin of the FDS insertion to the distal margin of the A2 pulley
2C	The area covered by the A2 pulley
2D	From the proximal margin of the A2 pulley to the proximal reflection of digital sheath

Figure 8-1 Zoning of the digital flexor tendons.

Figure 8-2 Pulleys and subdivisions of the digital flexor tendons (zones 1 and 2).

Etiologies and Evaluation of Tendon Injuries

Tendons can be injured through open wounds, caused by sharp cuts or machine injuries, as closed ruptures after fractures, through other bony problems, or even spontaneously, without history of injury or clear etiology. Severe forms of tendon injury can present as part of compound injuries due to major trauma to the extremities. Surgically repaired tendons may disrupt during functional exercise.

Tendon injuries often present as open injuries and are associated with a variety of open wounds. Open trauma with deep, narrow traumatic laceration should raise suspicion of concomitant tendon injuries. Such a diagnosis can be missed if surgeons do not carefully evaluate active motion of the potentially involved digits. When a tendon is partially cut, the fingers may still function well in many cases, easily causing such cuts to be neglected. Some larger partial cuts of the tendon may be detected through triggering during finger flexion. Large open traumas deep enough to reach the bony structures are usually accompanied by tendon injuries, which are not difficult to diagnose. Open trauma to the palm or wrist areas is frequently accompanied by tendon injuries. Trauma to the wrist area may injure only a part of the wrist flexors, without interfering in normal finger and wrist flexion. However, injuries to the majority of the wrist flexors cause weakness of wrist flexion and/or render active finger flexion impossible.

The levels of division of the tendons often do not lie immediately deep to the finger skin lacerations. The location of the distal tendon ends depends on the position of the fingers at the time of injury. If the finger is lacerated in flexion, the distal end of the tendon is drawn distally as the finger is extended. If the finger is lacerated in extension, the distal tendon end is usually found at the site of the laceration. The proximal tendon end often retracts to into the palm because of the pull of the muscles. When the laceration is in the distal half of the fingers, the vincula to the tendons may prevent the proximal tendon from retracting. Therefore, the proximal end of the lacerated flexor digitorum superficialis (FDS) or flexor digitorum profundus (FDP) tendons sometimes retracts over only a short distance and is still found within the digital sheath. The proximal end of the lacerated flexor pollicis longus (FPL) tendon usually retracts to the thenar area, or even more proximally, due to the vigorous pull of the muscle.

During examination, any changes in resting position of the fingers should be closely observed (Figure 8-3). In assessment of function of the FDP and FDS tendons, patients are asked to actively flex the fingers. Inability to actively flex the finger proximal interphalangeal (PIP) or distal interphalangeal (DIP) joints using the specific tests shown in Figures 8-4 and 8-5, when passive motion is complete, indicates that the FDP or FDS tendon (or both) is completely severed.

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Tags: Tendon Surgery of the Hand

Mar 5, 2016 | Posted by admin in Hand surgery | Comments Off

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