Extensor Tendon Repairs
Carol Recor, OTR/L, CHT
Jerry I. Huang, MD
Dr. Huang or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex and Trimed; serves as a paid consultant to Acumed and Arthrex; and serves as a board member, owner, officer, or committee member of the American Association for Hand Surgery, the American Society for Surgery of the Hand, and the Journal of Hand Surgery–American. Neither Ms. Recor nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article.
Introduction
Extensor tendon injuries of the fingers are quite common. However, since many extensor tendon lacerations are repaired in the emergency department, it is easy to disregard the impact and potential disability from an extensor tendon injury. While there is extensive published research regarding rehabilitation protocols following flexor tendon repairs, rehabilitation outcomes for extensor tendon repairs has received less attention.
The anatomy of the extensor tendons, with a flat profile and short distal excursion, combined with close approximation to bony structures and adjacent structures, requires thoughtful rehabilitation programs. In addition, the reduced size and tensile strength of finger extensor repairs, compared to that of flexor tendon repairs, require further consideration when advancing extensor tendon repair protocols. Failure of the extensor tendon repair leads of loss of digit extension, which can be quite disabling in activities of daily living (ADLs). Moreover, extensor tendon injuries can also lead to loss of finger flexion from scarring.
Due to the complex extensor tendon anatomy, there are a variety of injuries that present different scenarios for both surgical treatment and postoperative rehabilitation. Early intervention, with appropriate attention to the details and timing of therapy, is critical to achieving excellent functional outcomes. Communication between the surgeon and therapist is also critical, and the therapist’s role in patient education and monitoring for any early extensor lag cannot be understated.
Relevant Anatomy
The extensor mechanism of the hand is divided into eight anatomic zones. The odd-number zones are over the joints, starting with the distal interphalangeal (DIP) joint, and progress proximally; the even-numbered zones are over the bones. Zone VIII is over the distal forearm and contains the musculotendinous junction. In Zone VI, the junctura tendinae connect the extensor tendons of the middle, ring, and small fingers. Injuries proximal to the junctura are often missed, as patients can retain some extensor function. The location of an extensor tendon injury is important to consider in surgical decision-making, and directs the postoperative rehabilitation protocol.
Surgical Treatment
Indications
Extensor tendon injuries can occur from direct lacerations, complex open wounds, or from closed means with forced hyperflexion of the proximal interphalangeal (PIP) and DIP joints. Depending on the amount of tendon involvement and overlying soft-tissue injury, as well as associated bony injuries, operative intervention may be indicated. In general, surgical repair should be performed for tendon lacerations involving more than 50% of the tendon, or partial tendon lacerations with loss of finger extension strength. Injuries in Zones I through VI can often be irrigated and repaired primarily in the emergency department. If there is significant wound contamination or joint involvement, as in a Zone 5 “fight bite” injury over the metacarpophalangeal (MCP) joint, or soft-tissue loss, surgical débridement and repair should be performed in an operating room. More proximal injuries in Zones VII and VIII should also be treated in the operating room, as they often involve more extensive dissection for adequate surgical exposure. Surgical repair should be performed with 3-0 or 4-0 nonabsorbable sutures. Horizontal mattress or figure-of-eight sutures are used for more distal injuries, as the tendon is quite thin and flat. More proximally, if there is enough tendon substance, a core suture technique, such as a modified Bunnell or modified Kessler repair, is recommended.
 Figure 29.1 Illustration of four commonly used repair techniques for extensor tendon lacerations. (Reproduced with permission from Newport ML: Extensor tendon injuries in the hand. J Am Acad Orthop Surg 1997;5:59–66.) |
Lacerations and Open Injuries
Zones I and II
Procedure
We prefer performing extensor tendon lacerations in Zone I under local anesthesia with a digital nerve block. Our preferred skin incision is Y-shaped with a transverse limb over the DIP joint with midaxial incisions distally and proximal extensions dorsally over the midline. The terminal extensor injury in Zone I and Zone II lacerations is usually repaired with a figure-of-eight or horizontal mattress suture with nonabsorbable suture (4-0 nylon) (Figure 29.1). In more distal lacerations, the tendon is very thin and flat, and tenodermodesis is recommended, suturing the tendon and skin as one single layer. As it is very difficult to maintain the DIP joint in extension and protect the repair, it is best to pin the joint in extension with a 0.045-inch Kirschner wire (K-wire) and leave the PIP joint free. We bury the pin below skin and remove it at 8 weeks postoperatively under local anesthesia in the office.
Postoperative Rehabilitation
A static thermoplast DIP splint is fitted at 5 to 7 days postoperatively to protect the distal tip of the digit and the K-wire until the K-wire is removed (Figure 29.2). The splint may be removed for showering.
Use of the hand for heavy lifting or gripping is discouraged during this time until the K-wire is removed.
PIP joint active range of motion (ROM) exercises are initiated at 2 weeks.
Gentle active range of motion (AROM) is encouraged after pin removal.
Specific instructions provided to the patient, to monitor for development of extensor lag.
Orthosis should be resumed if extensor lag recurs, with progressive weaning of orthosis over the next 4 weeks.
Active functional hand use will allow the patient to regain grip strength without applying additional stress to the extensor tendon.
Home strengthening programs, such as Theraputty or similar strengthening modalities, should be avoided. Full unrestricted activities may be resumed at 8 weeks postoperatively in the absence of any extensor lag at the DIP joint.
Clinical Pearls
Full thickness skin flaps should be elevated to minimize flap necrosis and wound problems. Careful elevation of the distal skin flap is performed to avoid injury to the germinal matrix.
If mild extensor lag develops, we recommend use of an Oval-8 splint (3-Point Products, Stevensville, MD), which is adjusted to keep the PIP joint in slight flexion. This splint can be used for reverse blocking exercises to improve DIP joint extension (Figure 29.3).
 Figure 29.2 Photograph of a thermoplast clam-shell orthosis, which helps protect the K-wire tip over the fingertip as well as providing support to the distal interphalangeal joint. |
Zone III
Procedure
Extensor lacerations of the central slip in this zone are often associated with open fractures and contaminated wounds;
care should be taken to address the concomitant injuries. Thorough irrigation of the joint should be performed as well as repair of collateral ligament injuries. The surgical exposure is performed through a dorsal longitudinal incision over the PIP joint, incorporating the laceration. Alternatively, some surgeons prefer a curvilinear skin incision to avoid an incision directly over the lacerated tendon and repair sutures. Extensor tendon repair is performed with horizontal mattress or figure-of-eight sutures using nonabsorbable 3-0 or 4-0 sutures (Figure 29.1). Avulsion fractures off the dorsal base of the middle phalanx are common. With large fragments, fixation can be performed with 1.2-mm or 1.5-mm lag screws. With smaller fragments, surgical repair can be performed with 1 to 2 small suture anchors (1.8-mm or 2.2-mm anchors; Figure 29.4). If lacerated, the lateral bands are repaired separately using 5-0 or 6-0 sutures in a figure-of-eight fashion.
care should be taken to address the concomitant injuries. Thorough irrigation of the joint should be performed as well as repair of collateral ligament injuries. The surgical exposure is performed through a dorsal longitudinal incision over the PIP joint, incorporating the laceration. Alternatively, some surgeons prefer a curvilinear skin incision to avoid an incision directly over the lacerated tendon and repair sutures. Extensor tendon repair is performed with horizontal mattress or figure-of-eight sutures using nonabsorbable 3-0 or 4-0 sutures (Figure 29.1). Avulsion fractures off the dorsal base of the middle phalanx are common. With large fragments, fixation can be performed with 1.2-mm or 1.5-mm lag screws. With smaller fragments, surgical repair can be performed with 1 to 2 small suture anchors (1.8-mm or 2.2-mm anchors; Figure 29.4). If lacerated, the lateral bands are repaired separately using 5-0 or 6-0 sutures in a figure-of-eight fashion.
 Figure 29.3 Photograph of an oval 8 splint to keep the proximal interphalangeal joint in slight flexion, allowing for reverse blocking extension exercises for the distal interphalangeal joint. |
Postoperative Rehabilitation
Thermoplastic orthosis is used with the PIP joint in full extension to avoid extensor lag and the DIP joint left free for active motion (Figure 29.5). The authors prefer a three-quarter circumferential thermoplastic orthosis, which provides adequate support on both the dorsal and volar surfaces of the digit, with easy accommodation for fluctuations in edema.
Orthosis is used continuously for 6 weeks.
Active DIP joint ROM is initiated immediately, with the orthosis in place. This provides a mechanism for blocking exercises to isolate the DIP joint only. Active DIP joint flexion will pull the lateral bands dorsally and allow reapproximation of the central slip.
Figure 29.4 A, Plain radiograph of the base of a middle phalanx avulsion fracture of the central slip. B, Plain radiograph of fracture in A showing treatment with suture anchors with intraosseous sutures passed through the avulsion fragment.
Protected isolated active PIP flexion is initiated at 2 weeks, beginning with 15° of active flexion and increasing flexion an additional 15° each week. This is accomplished with a
progressive exercise orthosis, which the patient is using as a guide to block excessive flexion (Figure 29.6). Not only will this prevent a tendon rupture, it will also minimize the development of an extensor lag from early dorsal scar adhesions from immobilization.
If an extensor lag is noted, early protected active motion is discontinued for at least 1 week while the PIP joint is immobilized in full extension.Related posts:
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