David B. Shapiro and Mark A. Krahe
DEFINITION
Traumatic disruptions of the extensor mechanism represent a broad spectrum of injuries, frequently seen because of the tendons’ superficial location, and frequently associated with concomitant injury to bone, skin, and joint.15
Repair can be technically demanding. The extensor tendons are thin, have limited excursion, and are intolerant of shortening, especially in the digits.
Reconstruction of subacute and chronic extensor tendon injuries are more challenging and less effective than early repair, underscoring the importance of appropriate treatment of an acute injury.
ANATOMY
Extensor tendon zones of injury (Verdan) (FIG 1A)13
The extensor mechanism is divided into eight zones in the fingers and five in the thumb, numbered from distal to proximal.
Even-numbered zones are over bones and odd-numbered ones are over joints.
Extrinsic extensors (FIG 1B and Table 1)
Digital and wrist extensor muscles originate from the lateral epicondyle and condyle, with musculotendinous junctions 3 to 4 cm proximal to the wrist joint. The extensor indicis proprius (EIP), extensor pollicis longus (EPL), abductor pollicis longus (APL), and extensor pollicis brevis (EPB) all originate more distally from the ulna, the radius, or both and have more distal extension of muscle fibers.
The four extensor digitorum communis (EDC) tendons originate from a common muscle belly and have progressively limited independence moving from the index to small fingers.
The fascia over the extensor tendons thickens at the wrist to form the extensor retinaculum, with vertical septa separating the six extensor compartments (FIG 1B).
Juncturae tendinum provide interconnections between the EDC tendons just proximal to the metacarpophalangeal (MCP) joints.
FIG 1 • A. Extensor tendon zones of injury. B,C. The digits are to the left and the wrist is to the right. B. The top of the figure is radial and the bottom is ulnar. Wrist and hand extensor tendon anatomy, with numbers to identify the extensor tendon compartments. R is the reflected extensor retinaculum and J is a junctura tendinum. Note the combined extensor digitorum communis (EDC) tendon to the ring and small finger. In the fourth compartment, the extensor indicis proprius (EIP) tendon is deep to the EDC tendons and has more distal muscle fibers. In the hand, it is just deep and ulnar to the index EDC tendon. See Table 1 for more details. C. The digital extensor mechanism. 1.Terminal tendon. 2. Triangular ligament. 3. Proximal interphalangeal (PIP) joint. 4. Central slip tendon. 5. Sagittal band. 6. Lateral band, which will become the terminal tendon distally. 7. Conjoined lateral band, with fibers to base of middle phalanx and to the lateral band. This patient has an unusual proprius tendon to the long finger (*), passing ulnar to the EDC tendon and beneath the junctura.
The EIP and extensor digiti minimi are ulnar and deep to the EDC in the hand and at the MCP joint.15 The EIP passes beneath the junctura tendinum.
There can be considerable variability of the extensor tendons on the dorsum of the hand, with less than 50% of people having a separate EDC tendon to the small finger.19 Duplicated, interconnected tendons are common.11
The sagittal band holds the extensor tendon over the metacarpal head at the MCP joint, and, through its connection to the volar plate, extends the joint.
Intrinsic extensors (FIG 1C)
Intrinsic extensors originate in the hand and include the four dorsal interossei, three palmar interossei, and four lumbricals. The thenar and hypothenar muscles also contribute to interphalangeal extension.
The intrinsic tendons join to form the conjoined lateral bands volar to the axis of the MCP joint, and continue dorsal to the axis of the proximal (PIP) and distal (DIP) interphalangeal joints.1,19 This allows them to simultaneously flex the MCP joint and extend the PIP and DIP joints, in addition to providing digital adduction and abduction.
PATHOGENESIS
Zone I
Disruption of the extensor tendon over the DIP joint will result in a terminal extensor lag after an open or closed injury (FIG 2).
Sudden forced flexion of the extended DIP joint can lead to an avulsion of the tendon from its insertion on the distal phalanx (mallet finger), possibly with an associated distal phalanx fracture.
The long, ring, and small fingers are most frequently involved, although closed mallet injuries can also be seen in the index finger and thumb.1
Zone II
Laceration over the middle phalanx can give the clinical appearance of a zone I injury.
Injury to the periosteum and middle phalanx can lead to increased swelling, extensor tendon adherence, and DIP stiffness.
Zone III
Disruption of the central slip at the PIP joint may occur as a closed rupture (with or without an associated bone injury) or be associated with traumatic arthrotomy.
Central slip avulsion is seen with volar PIP joint dislocations.
Early closed injuries may present with swelling, pain, and little extension loss but can progress to a boutonnière deformity as the lateral bands migrate palmarly and become flexors of the PIP joint in the weeks after injury.19 Close follow-up is warranted for suspicious injuries.
Zone IV
Injuries occur over the proximal phalanx and typically involve only a portion of the extensor mechanism.
Lacerations are usually partial as the extensor “hood” covers almost 75% of the circumference of the digit. With a complete central slip laceration, PIP extension may be maintained (through the lateral bands) initially, although a boutonnière deformity may develop later.
Differentiation between complete and incomplete injury can be difficult, but pain or weakness with resisted PIP extension (especially from an initially flexed position) can be suggestive. As above, close follow-up is warranted for suspicious injuries.
Zone V
Tendon injury occurs over the MCP joint.
There may be an open laceration or a closed injury to the sagittal band with extensor tendon subluxation.
Most frequently, the radial sagittal band is disrupted in closed injuries allowing ulnar subluxation of the extensor tendon.
The surgeon should assume there is an open MCP joint injury with any tendon laceration around the joint.
Zone VI
Disruption of extensor tendon is over the dorsum of the hand.
Single tendon and partial tendon lacerations may be difficult to identify due to maintenance of some digital extension though an intact junctura tendinum and EDC tendon from an adjacent digit (FIG 3).
FIG 2 • Mallet finger. (Zone I extensor tendon injury.)
FIG 3 • Extensor digitorum communis laceration to the long finger at the asterisk. The long finger can still be extended by action of the ring extensor and junctura tendinum. This may be associated with long-term weakness, pain, or extensor lag.
Zone VII
Lacerations occur over the wrist and through the extensor retinaculum.
Zone VIII
Pathology is located in the forearm at the musculotendinous junction or muscle belly.
It may be difficult to detect concurrent posterior interosseous nerve injury in the presence of proximal extensor muscle lacerations.
Thumb
The terminal extensor tendon is thicker than in other digits—mallet injury is rare.
Tendon lacerations at, and distal to, the MCP joint are not associated with retraction of tendon ends, and primary repair is straightforward. Lacerations proximal to the MCP joint are associated with EPL retraction (often to the wrist).
NATURAL HISTORY
Untreated complete tendon lacerations at and distal to zone V will lead to persistent (and sometimes progressively worsening) digital deformity, often with continued pain and development of a flexion contracture.
Untreated terminal tendon injuries may lead to a swanneck deformity due to proximal migration of the digital extensor mechanism and increased extension force at the PIP joint.
Delayed treatment of central slip injuries may lead to boutonnière deformity and PIP flexion contracture as the lateral bands migrate palmarly.
Untreated tendon lacerations proximal to zone V will heal in lengthened fashion with pseudotendon formation. There may be a persistent extensor lag, weakness, or pain. Gradual loss of muscle length and elasticity (sometimes within as little as a week or two) can make delayed primary repair more difficult.
EPL tendon lacerations proximal to the MCP joint may be difficult to primarily repair as little as 2 weeks after the injury, requiring tendon grafting or EIP transfer.
Partial tendon lacerations involving less than 50% of the tendon width, longitudinal lacerations, and single lateral band lacerations will generally function well without repair.
PATIENT HISTORY AND PHYSICAL FINDINGS
Assessment and documentation of skin and soft tissue injury is important to aid in planning for débridement and extension of the skin incision for exposure and determining the need for soft tissue coverage.
A complete neurologic and tendon examination is critical to rule out concurrent or remote injury that will alter treatment or outcome.
The EIP is examined. It is deep to other extensor tendons, with the most distal musculotendinous junction.
The extrinsic extensor tendons are examined with the wrist in neutral, testing MCP extension against resistance. (Isolated PIP extension can be performed by the intrinsic muscles even in the presence of complete extrinsic extensor tendon lacerations.)
Examination of the digits may identify extensor lag, weakness, or pain with resistance to extension at the PIP or DIP joints.
Active and passive range of motion and strength are assessed. Active motion loss helps determine tendon deficits, while loss of passive motion may be pain-related or represent remote injury or arthritis. Lacerations proximal to the juncturae tendinum may have nearly full motion, but with weakness on strength testing (FIG 3).
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs are necessary to evaluate for any fractures, foreign bodies, preexisting injury, or arthritis that may alter treatment or affect the final result.
Ultrasound or MRI are occasionally useful for suspected radiolucent foreign bodies. While both studies can be used to more fully evaluate tendon injuries, treatment decisions are usually based on history and physical examination.
DIFFERENTIAL DIAGNOSIS
Radial nerve or posterior interosseous nerve injury
Extensor tendon subluxation at the MCP joint
Chronic PIP flexion contracture and “pseudo-boutonnière” deformity
Physiologic swan-neck deformity or DIP joint osteoarthritis with apparent mallet deformity
Underlying joint deformity and arthrosis
NONOPERATIVE MANAGEMENT
Disruption of the terminal extensor tendon (mallet finger)
Treatment consists of full-time static DIP splinting for 6 to 8 weeks, followed by an additional 6 weeks of protective splinting at night and with high-risk activities.
Patients must be counseled as to the importance of maintaining full DIP extension, even during splint changes.
A dorsal splint (FIG 4A) can allow the patient nearly full use and sensibility of the digit, although palmar or thermoplastic splints can be used in some cases (provided that full DIP extension can be ensured). A good fit without excessive DIP hyperextension which can cause skin injury is critical.
The PIP is generally left free and motion encouraged. For patients with moderate PIP hyperextension, the PIP may be flexed 30 degrees and incorporated in the splint for the first 3 weeks of treatment.
Treatment can be initiated as late as 4 months after the original injury and still lead to a good result, although a couple more weeks of full-time splinting may be necessary.7
FIG 4 • A. Example of mallet finger splint. Any type of distal interphalangeal (DIP) joint splint will work, as long as the DIP is extended to neutral, and the splint is worn full time. B. Example of hand-based splint to support metacarpophalangeal joint.
Final results: About 80% of patients should regain full flexion with less than a 10-degree extensor lag. Patients with a greater extension lag after 6 weeks may benefit from 2 or 3 more weeks of full-time splinting. Swelling around the DIP joint can persist for months.
Central slip avulsion
This is treated with full-time static PIP splinting in extension, with active and passive DIP flexion encouraged for 6 weeks, followed by 6 weeks of night splinting.
Intermittent use of dynamic extension splint is warranted for PIP flexion contracture.
Closed sagittal band rupture
The patient is placed in a below-elbow cast with the MCP joints supported in full extension (to allow no more than 10 degrees of flexion) for 6 weeks.
Compliant patients can be switched to a hand-based splint after 3 weeks of casting with the MCP joint supported in 30 degrees of flexion (FIG 4B).
Surgical treatment is indicated for closed ruptures presenting more than 2 weeks after injury or those that do not respond to conservative treatment.
Partial extensor tendon lacerations
Conservative treatment is indicated if the laceration is known to involve less than 50% of the tendon width and in longitudinal tendon lacerations.
If the degree of injury is unknown, conservative treatment should be considered in patients with full active extension, minimal or no pain with resisted extension, and good extension strength. Surgical exploration and repair is indicated if there is an extensor lag, weakness, or pain with resisted extension.
Partial digital extensor tendon lacerations are treated in the manner described earlier, with splinting for 2 to 3 weeks, followed by a monitored gradual exercise program to ensure that an extensor lag does not develop.
Partial hand and forearm extensor tendon injuries are treated similarly. A splint or cast is used for 3 weeks with mild wrist extension and 30 degrees of MCP flexion. The PIP joints are left free.
SURGICAL MANAGEMENT
Preoperative Planning
A careful examination is performed to determine the structures that are injured or will need repair (eg, open joint injuries, fractures, flexor tendon or nerve injuries) and to inform the patient of the extent of the procedure, anticipated rehabilitation, need for occupational and non-occupational restrictions, and expected outcome.
If the wound is infected at the time of presentation, irrigation and débridement should be followed by a course of antibiotics. Delayed primary tendon repair can be carried out 7 to 14 days later (sooner for EPL lacerations proximal to the MCP joint and EDC lacerations proximal to the juctura).
The surgeon should anticipate the need for tendon graft or transfer for subacute injuries or those with tendon loss.
Local anesthesia and a digital tourniquet can be used for injuries distal to the PIP joint. The need for an upper arm tourniquet for more proximal injuries may necessitate a general or regional anesthetic, unless the anticipated surgical time is less than 30 minutes. Regional anesthesia can offer extended postoperative pain relief and muscle relaxation during the initial recovery period.
Positioning
Standard positioning is used with the hand on a hand table and the surgeon at the head.
Preparation and draping is done above the elbow to allow dressing and splint application before removal of drapes.
A carefully padded tourniquet is applied, set to 100 mm Hg above systolic blood pressure (sometimes more for obese patients, and less for children or those with small arms).
Approach
Wound exploration and débridement are performed in a bloodless field, with appropriate light and magnification. Injuries over a joint usually require joint exploration and irrigation.
The skin laceration can be extended to improve exposure, allow retrieval of retracted tendons, provide access to place sutures, and to decrease skin tension during retraction. Long, narrow skin flaps are avoided. Longitudinal incisions on the dorsum of the hand and fingers can cross over joints (unlike on the digital flexor surface).
Bipolar electrocautery is used as needed, with care taken not to injure dorsal cutaneous nerves. If there is any doubt regarding hemostasis, the tourniquet is deflated before closure. Drains are seldom needed.
Only the skin in the fingers, hand, and distal forearm is closed, with limited subcutaneous sutures more proximally if needed.
TECHNIQUES
SUTURE TECHNIQUES
Suture technique is determined by the thickness and shape of the tendon and the nature and character of the laceration (TECH FIG 1).
Thin tendons (eg, in digits) can be repaired with a horizontal cross-stitch suture (Silfverskiöld), simple running, figure 8, or horizontal mattress suture using 4-0 or 5-0 braided or monofilament nonabsorbable material.
Thicker tendons can support a twoor four-strand grasping repair with a 2-0, 3-0, or 4-0 nonabsorbable braided suture (eg, Ethibond, Ticron, or Fiberwire), optionally reinforced with a 5-0 or 6-0 monofilament epitendinous suture placed in a simple running or cross-stitch fashion.
In general, repair strength is related to number of suture strands crossing the repair site, the thickness of the suture, and the locking style of the stitch.
TECH FIG 1 • Some suture techniques for extensor tendon repair. The strongest repairs are the Silfverskiöld cross-stitch for flat tendons, and the four-strand cruciate suture for tendons able to accept a core suture. A. Running suture. B. Horizontal mattress. C. Silfverskiöld cross-stitch (which can also be used as a circumferential epitendinous tidying suture over a core suture). D. Modified Kessler. E. Modified Bunnell. F. Krackow. G. Four-strand cruciate suture.
REPAIR IN THE FINGERS
Zone I (DIP Joint)
Soft Tissue Mallet Treatment
In patients with closed tendon disruptions who cannot tolerate a splint for occupational reasons, pinning across the DIP joint with a 0.045-inch Kirschner wire exposed at the tip or buried under the skin may be indicated. Pin removal is performed 6 weeks later, followed by motion exercises and 6 weeks of splinting at night and during vigorous activity.
Lacerations in zone I are treated with primary surgical repair.
A figure 8 or running cross-stitch with a 5-0 nonabsorbable suture can be placed in the tendon, taking care to avoid shortening the tendon. This is supported with a 0.045-inch Kirschner wire across the DIP joint for 6 weeks. The DIP should be in neutral extension, without hyperextension.
An easier and often better alternative is use of a “tenodermodesis” stitch of 4-0 nylon through both the tendon and skin (TECH FIG 2).4,10 This can be especially useful in cases treated in the emergency room, or in children, where the small tendon is difficult to accurately repair.
Full-time extension splinting (as in a closed mallet finger) or a 0.045-inch Kirschner wire across the extended DIP joint is required.
The suture can be removed in 2 to 3 weeks, but the splinting should continue for a total of 6 weeks full time and another 6 weeks at night.
Bony Mallet Treatment
It remains controversial whether mallet fractures with greater than 50% of the distal phalanx involved or with DIP joint subluxation should be treated surgically or by splinting alone. Surgery is more likely warranted in younger patients and those with greater amounts of subluxation.21 If conservative management is being considered, be sure to obtain a good lateral radiograph with the digit in the DIP splint, as DIP extension to neutral may demonstrate subluxation that was not apparent when the joint was flexed.
A large bone fragment is present, with subluxation of the DIP joint (TECH FIG 3A,B).
Place a 0.045-inch Kirschner wire down the shaft of the distal phalanx, almost to the DIP joint.
Maximally flex the DIP and place a 0.035-inch Kirschner wire at the anticipated location of the reduced dorsal fragment of the distal phalanx. The skin entry point is relatively distal to enable pin movement in the next step. Hold the pin against the middle phalanx (TECH FIG 3C).
TECH FIG 2 • Tenodermodesis can be a useful way of suturing terminal tendon lacerations, especially in the emergency department or office. The suture (passing from left to right in A) goes through the skin and tendon proximally and distally.
TECH FIG 3 • Technique for pinning a mallet fracture. A,B. Large bone fragment is present, frequently with subluxation of the distal interphalangeal (DIP) joint. C. A pin is placed in the distal phalanx. Maximally flex the DIP and place a 0.035-inch Kirschner wire where you would anticipate the dorsal edge of the distal phalanx to be. The skin entry point is relatively distal, to enable pin movement in the next step. D,E. Angle the wire distally, pushing the fragment and buttressing it. Advance the wire into the middle phalanx. F,G. Extend and reduce the distal phalanx, bringing it up to the fragment, and stabilizing it by advancing the 0.045-inch Kirschner wire across the DIP joint. If a significant articular step-off persists after a couple tries, leave the longitudinal wire and allow the fragment to heal where it lies. H. Dorsal pins buttress the fragment, and the longitudinal pin reduces the flexion and subluxation. I. Pins bent to fit in a single pin cap.
Angle the wire distally, pushing the fragment distally and buttressing it. Advance the wire into the middle phalanx (TECH FIG 3D,E).
Extend and reduce the distal phalanx, bringing it up to the fragment. Drive the 0.045-inch wire across the DIP joint. Maintain full extension and correction of any subluxation (TECH FIG 3F–H).
Bend the pins so they can be included in a single pin cap to prevent rotation or movement of the proximal pin (TECH FIG 3I).
If an articular step-off persists after a couple of attempts, remove the dorsal wire but leave the longitudinal wire in place supporting the joint in neutral extension and correcting the subluxation. This may leave a dorsal prominence but will correct the subluxation.
Pins can be removed in about 6 weeks with institution of a protected motion program and 4 to 6 weeks of additional night splinting.
Zone II (Over Middle Phalanx)
Perform primary tendon repair with a running 4-0 or 5-0 cross-stitch suture.
The DIP joint can be splinted or pinned extended for 6 weeks, followed by splinting for vigorous activity and at night for 6 weeks.
Zone III (Over PIP Joint)
Use a running 4-0 or 5-0 suture to repair the central slip in the manner detailed earlier (TECH FIG 4).
Repair the lateral band or bands with single 4-0 or 5-0 monofilament suture in a figure 8 fashion.
Reconstruction in Cases with Tendon Loss
Consider V-Y advancement of the central tendon or a “turndown” of the central slip proximal to the laceration to cover the defect.20
Extend the skin incision proximally, almost to the MCP joint.
Incise a V in the central slip, with the apex just distal to the MCP joint, and the distal end the width of the tendon, taking care not to damage the overlying epitenon (TECH FIG 5A, red line).
Advance the tendon distally. Disrupt the loose alveolar tissue between the tendon and periosteum as little as possible.
Close the V into a Y with a 4-0 or 5-0 suture, and repair the distal end of the advanced central slip as described earlier (TECH FIG 5B).
An alternative method involves creating a rectangular flap of central slip proximally and turning it up to attach distally (TECH FIGS 5A,C,D).20
Suture anchors or small holes drilled in the middle phalanx are occasionally needed to secure the tendon to the dorsal base of the middle phalanx, especially if the dorsal margin of the base of the phalanx is lost.
TECH FIG 4 • Simulated central slip laceration on a cadaver specimen. Note how difficult it would be for a laceration to cut all the way around the extensor mechanism. This example has been repaired with a running, cross-stitch suture (Silfverskiöld).
Postoperative Management
Postoperative rehabilitation for children, less compliant adults, and cases with a tenuous repair involves static splinting or pinning of the PIP joint in full extension for 4 weeks, followed by a protected motion program.
For compliant adults, an early motion protocol can be initiated.6
0 to 30 degrees of active PIP flexion and extension is allowed starting a few days after surgery, using a palmar flexion block splint with a free wrist and MCP joint.
10 to 20 repetitions are performed each hour, with a static PIP splint in full extension when not exercising.
DIP flexion exercises are performed in the static PIP extension splint.
If no extensor lag develops, PIP motion can be increased to 40 degrees after 2 weeks, 50 degrees after 3 weeks, and 70 degrees after 4 weeks. The splinting is discontinued at 6 weeks.
Results are often less than perfect, especially in cases with tendon loss, where some loss of motion should be expected.
Zone IV (Over Proximal Phalanx)
The tendon at this level may be thicker and support a grasping or locking core stitch with a 4-0 braided nonabsorbable suture, reinforced with a running 5-0 monofilament suture.
If the tendon is too thin, repair as in zone III.
Postoperative management is as in zone III.
TECH FIG 5 • A. Central slip loss (eg, abrasions, grinders) can lead to significant stiffness. B. V-Y advancement of the central tendon.
REPAIR IN THE HAND, WRIST, AND FOREARM
Zone V (Over the MCP Joint)
The tendon is much thicker at this level and can sometimes support a 3-0 or 4-0 braided nonabsorbable core suture with a running simple or cross-stitch suture over the repair, incorporating any laceration of the sagittal band.
An abnormal resting cascade of the digits suggest a tendon laceration (TECH FIG 6A).
Lacerations over the MCP joint often extend into the joint. The skin laceration is extended and débrided and the wound explored. Large capsular rents (arrow in TECH FIG 6B) can be repaired with a simple running 5-0 absorbable monofilament suture. Small capsular lacerations are left open.
The tendon end is retrieved, and a 3-0 nonabsorbable core suture is placed. The first loops of the cruciate stitch are shown (TECH FIG 6C).
TECH FIG 6 • Zone V repair. A. There is a preoperative laceration around the metacarpophalangeal (MCP) joint and loss of long finger extension. B. The arrow points to a rent in the MCP joint capsule, seen only with flexion of the joint. C. The first loops of the cruciate stitch are placed. D. The gap is closed. Since the stitch will not slide, slack is taken off each limb and the individual loops are tightened. E. The core is completed and tied. F. Reinforcement with a 5-0 nonabsorbable monofilament suture. G. Resting posture of the hand after repair. H. Forearm-based splint.
The distal locking stitch is placed on one side of the tendon but not pulled tight until the tendon ends are accurately approximated. The limbs of the X are individually tightened (TECH FIG 6D).
The core suture is completed and will not slide (TECH FIG 6E).
The repair is reinforced with a 5-0 nonabsorbable monofilament suture. This can be circumferential proximal to zone V, but only over the dorsal surface of the tendon distally (TECH FIG 6F).
The resting cascade of the digits shows the repaired finger to be slightly “tighter” than normal immediately after the repair (TECH FIG 6G).
A forearm-based splint is applied with 30 degrees of wrist extension, less than 30 degrees of MCP flexion, and fully extended PIP and DIP joints (TECH FIG 6H).
After 8 to 10 days, this splint is converted to a short-arm cast supporting the MCP joints in extension (including all fingers for index lacerations and the ulnar three for other lacerations) but leaving the PIP joints free for another 3 weeks before institution of a therapy program.
Alternatively, an early protected motion program can be initiated.3,9
Repair of Distal “Compromised” Zone V Lacerations
In this clinical situation a standard end-to-end repair may be tenuous or may not be possible secondary to contracted or lost tendon substance. A tendon interpositional graft may be required.
Partially incise the distal tendon transversely 5 mm distal to the cut edge.
Weave tendon graft in a volar to dorsal direction through this transverse incision in the distal stump.
Sew the graft to the proximal stump to the distal tissue and back to itself using nonabsorbable material (TECH FIG 7).
Sew the proximal stump to the tendon graft using a Polvertaft weave.
Zone VI (Metacarpal Level)
The tendon is thicker and repair is similar but technically easier than in zone V.
TECH FIG 7 • Tendon graft is woven volar to dorsal through the transverse incision in the distal tendon stump. A Polvertaft weave is used to secure the graft to the proximal tendon stump.
Use a 3-0 or 4-0 braided nonabsorbable suture, reinforced with a circumferential running cross-stitch 5-0 or 6-0 monofilament suture.
Rehabilitation is as for zone V.
Zone VII (Wrist and Extensor Retinaculum)
Suture repair and postoperative management are as in zone VI.
The extensor retinaculum is incised for repair and retrieval of the proximal tendon stump.
Retinacular closure is performed with a 4-0 absorbable suture to prevent tendon bowstringing. A portion of the retinaculum may need to be excised to allow the repair site to glide smoothly.
The EPL can be repaired outside of the retinaculum and left in the subcutaneous tissue.
Postoperative management is the same as for Zone V injuries.
Zone VIII
Make a generous incision to determine the resting orientation of the tendons before débridement and repair. It may be helpful to tag proximal tendon ends with labels to define them before further dissection changes their position.
In the distal forearm, conventional repair with grasping sutures is possible. EDC tendons can be repaired as a group if necessary.
Proximally, repair can be much more difficult. 3-0 interrupted absorbable sutures can be used in fibrous septa within muscle along with repair of epimysium.
Postoperative management is as for zones V to VII.
POSTOPERATIVE CARE
Postoperative care is detailed under the surgical technique for each individual location.
OUTCOMES
Good or excellent results can be anticipated in most patients, with worse outcomes seen in the digits and with concomitant soft tissue or bone injury. Loss of digital flexion is a greater problem than small losses of extension.2,16
Stronger suture techniques and early dynamic postoperative protocols may result in better functional outcomes earlier,17 al though few controlled studies show improvement in long-term results when compared to static splinting programs, which are easier, more predictable, and less expensive.12,14 Early motion programs may be most beneficial in zones III and IV.
COMPLICATIONS
Infection
Rupture of repaired tendons
Stiffness
Primary joint stiffness after immobilization
Adherence of repaired tendon to surrounding skin, bone
Extensor lag
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