Flexor and Extensor Tendon Injuries

Suture material

A variety of satisfactory suture materials are available for tendon repair. Although monofilament stainless steel has the highest tensile strength, it is difficult to handle, tends to pull through the tendon, and makes a large knot. Although it can be used satisfactorily in the distal forearm, its disadvantages limit its use in the fingers. Most absorbable sutures, including catgut and the polyglycolic acid group (Dexon, Vicryl), become weak too early after surgery to be effective in tendon repair. Synthetic sutures of the caprolactam family (Supramid) and nylon maintain their resistance to disrupting forces longer than polypropylene (Prolene) and polyester suture. Polydioxanone (PDS) has been shown to be as strong as polypropylene. A comparison of polyglycolide-trimethylene carbonate (Maxon) and polydioxanone found that the polydioxanone repairs maintained better strength over 28 days. Monofilament nylon permitted earlier gap formation and failure of the repair compared with braided polyester. In a biomechanical study, braided polyethylene and braided stainless steel wire were most suitable mechanically. Braided polyester was intermediate, and monofilament sutures of nylon and polypropylene were least satisfactory. In clinical situations, most surgeons find that the braided polyester sutures (Ticron, FiberWire, Mersilene) provide sufficient resistance to disrupting forces and gap formation, handle easily, and have satisfactory knot characteristics; consequently, these sutures are widely used.

A 4-0 suture is estimated to be 66% stronger than a 5-0 suture, and a 3-0 suture 52% stronger than a 4-0 suture. Based on cadaver experiments, the use of a 3-0 suture results in a twofold to threefold increase in fatigue strength and a 3-0 suture in a two-strand or four-strand configuration is recommended if an early active motion program is used. In most situations, a 3-0 suture may be useful to repair tendons in the forearm, palm, and larger digits, whereas a 4-0 suture may handle better in smaller digits. Epitendinous repair usually is done with 5-0 or 6-0 monofilament suture (Prolene).

Several newer devices and technologies appear promising. In a cadaver biomechanical analysis, an intratendinous, crimped, single-strand, multifilament stainless steel device (Teno Fix; Ortheon Medical, Winter Park, FL) compared favorably with four-strand cruciate repairs. A multicenter, randomized, and blinded clinical trial compared the stainless steel tendon repair device with a control group of four-strand cruciate suture repairs. The intratendinous device group had a lower rupture rate (0 vs. 18% in the controls) and compared favorably in other outcome measures, such as grip and pinch strength and DASH (disability, arm, shoulder, hand) scores. More clinical reports are needed using this device, the motion-stable wire suture of Towfigh, and the shape memory alloy suture to determine their place in the management of flexor tendon injuries. The use of the neodymium: yttrium-aluminum-garnet laser does not seem to weld tendons, according to a study in chickens. A knotless barbed suture has been described in the literature. One study found it to be as strong as a four-strand configuration for epitendinous repair, while one cadaver study found the barbed suture technique to be inferior to the conventional 4-0 suture with cyclic loading.

Suture Configurations

In the process of seeking the strongest intratendinous suture arrangement to allow early passive and active motion, numerous suture configurations at the repair site have been developed and studied ( Fig. 66.5 ).

An abundance of research has shown that four-strand, six-strand, and eight-strand core sutures create stronger repairs, reduce the possibility of gap formation, and permit greater active forces to be applied to the repaired tendons, allowing earlier active motion than the traditional two-strand core sutures ( Fig. 66.6 ). A global survey of clinical practices by Tang et al. confirms the efficacy of multistrand (four to eight) 3-0 or 4-0 core sutures with 6-0 epitendinous sutures. A human cadaver comparison of the Kessler, modified Kessler, Savage, Lee, augmented Becker, and Tsuge core suture methods by Zobitz et al. found no difference in maximal failure force or force to produce a 1.5-mm gap. Continuing the interest in multiple-strand modifications, such as those of Savage (six strands) ( Fig. 66.7 ) and Lee (four strands) ( Fig. 66.8 ), the grasp of a “cross-stitch” ( Fig. 66.9 ) of 6-0 braided polyester was found to be 117% stronger than a modified Kessler core suture with a conventional epitendinous repair.

The locked cruciate, the modified double Tsuge, and the modified Becker repairs have been shown to provide sufficient strength to support an early active motion rehabilitation program. The Tang and cruciate repairs ( Fig. 66.10 ) have shown better tensile strength and elastic properties compared with the Silfverskiöld, Robertson, and modified Kessler repairs.

A cadaver study found that the cruciate four-strand suture technique provided stronger resistance to gap formation and had greater ultimate tensile strength than the Kessler, Strickland, or Savage techniques. When Kessler, Strickland, and modified Becker techniques were compared, only the Becker repair was strong enough to tolerate forces estimated for an active motion rehabilitation plan. The Strickland repair had less tendency to gap. In a group of canine tendons, the Becker repair was associated with greater friction between the tendon and sheath than the modified Kessler repair. A four-strand adaptation of the Kessler repair was found to be significantly stronger than the modified Kessler technique ( Fig. 66.11 ). It is a straightforward modification that might be done with more ease in areas of the flexor sheath where access to the tendon is limited. Such techniques allow satisfactory purchase on the tendon so that satisfactory tensile strength is maintained during the early healing phase. Early active motion rehabilitation programs may have a beneficial effect on tendon healing and may reduce adhesion formation significantly.

Intratendinous crisscross suture techniques (Bunnell, Kleinert modification of Bunnell) tend to jeopardize the intratendinous circulation ( Fig. 66.12 ). Although placement of sutures in the volar half of the tendon has been recommended to avoid injury to the circulation, experimental work showed that the mean strength of repairs sutured in the dorsal half of the tendon was 58.3% greater than that in the volar half. Locking the sutures as they pass through the tendons traps bundles of the tendon fibers, preventing the suture from pulling out of the tendon and increasing the resistance to gap formation. These techniques have been shown to be dependable in the fingers. No suture material or technique can be relied on to maintain tendon repairs with unlimited active movement in the early postoperative period. Most investigators report that the strength of the tendon repair diminishes considerably in the first 10 days. Thereafter, the strength of the repair gradually increases, so that by the end of 10 to 12 weeks considerable active forces can be applied in the rehabilitation program.

Continuous epitendinous sutures, placed circumferentially around the repair site, decrease the bulk of the repair site, minimizing the risk of triggering. This addition also enhances the strength of the core suture repair, supports 50% of the load to failure, and resists gap formation. In biomechanical tests of human cadaver tendons, the epitenon-first technique ( Fig. 66.13 ) was found to be 22% stronger than the modified Kessler technique. A comparison of four circumferential techniques without core sutures in sheep tendons found that the interlocking horizontal mattress suture had the highest load to failure, greatest resistance to gap formation, and highest stiffness and was believed to be best overall ( Fig. 66.14 ). Peripheral sutures placed 2 mm from the repair site provide a stronger repair than placement of the sutures 1 mm from the repair site.

To minimize compression and bulking of the repair site, most techniques advocate the placement of temporary or permanent partial epitendinous sutures to secure the tendon ends before placement of core sutures. The partial epitendinous repair can then be completed or removed if a cross-stitch type of epitendinous repair is preferred. Alternatively, a tendon approximator or hypodermic needles can be used to stabilize the tendon ends in apposition so that the core suture is not used to approximate the ends.

End-to-End Suture Techniques

Double Right-Angled Suture

To suture the severed ends of a tendon together without shortening, a double right-angled stitch can be used. This suture technique is useful proximal to the palm. Although the apposition of the tendon ends is not as neat as after the other end-to-end suture techniques described, the method is easier and is used more often when several tendons have been severed in the distal forearm and proximal palm ( Fig. 66.18 ).

Fish-Mouth End-To-End Suture (Pulvertaft)

A tendon of small diameter can be sutured to one of large diameter by the method shown in Figure 66.19 . This method commonly is used to suture tendons of unequal size.

Tendon-to-Bone Attachment

The attachment of tendon to bone (usually distal phalanx) for repair or grafting frequently requires a pull-out technique. Several methods have been described ( Figs. 66.22 and 66.23 ). Tendon-to-tendon repair of grafts may be preferable in children to avoid physeal injury ( Fig. 66.24 ). For tendon-to-bone repairs, the core suture techniques used most often have included the Kessler and a modification of the Bunnell crisscross suture ( Fig. 66.25 ) in which the pull-out wire is looped over a straight needle that is passed transversely through the tendon approximately 10 mm from the cut end. This leaves the pull-out wire attached to a loop of the suture proximally in the tendon to be passed into the bone distally ( Fig. 66.26 ).

Suture Anchor Tendon Attachment

The use of a suture anchor has been shown to be as effective as a pull-out wire or suture but without the potential complications with the fingernail that can occur with the pull-out technique. Two suture anchors are placed in the distal phalanx from distal-volar to proximal-dorsal so that they gain purchase in the thickest portion of the distal phalanx to provide the greatest pull-out strength ( Fig. 66.28 ).

Partial flexor tendon lacerations

After partial tendon lacerations, complications reported by many authors include rupture, triggering, and tendon entrapment. Experimental work suggests that a partially lacerated tendon retains varying amounts of its strength. A tendon with a 60% laceration can retain 50% or more of its strength and a tendon with a 90% laceration can retain only slightly more than 25% of its strength. Studies in human cadaver tendons found that the loads required to rupture 50% and 75% tendon lacerations were higher than the physiologic loads measured during normal active motion. In canine flexor tendons with lacerations of 30% and 70% of the cross-sectional area, with and without repair, no significant differences were seen in the structural properties of the repaired versus the unrepaired tendons, suggesting that partial lacerations of 70% of the cross-sectional area could be treated without repair. Excellent results were reported in 14 of 15 patients treated conservatively with “greater than half the width” partial lacerations of flexor tendons in zone II. Considering these findings, a reasonable clinical approach to managing the major problems related to partial tendon lacerations would be as follows.

If a tendon is lacerated 60% or more it is treated the same as a complete transection. A core suture is placed in the tendon, and the surface of the tendon is sutured with a continuous 6-0 nylon suture. The flexor sheath is repaired when possible. Postoperative management of a 60% or greater tendon laceration is the same as for a complete transection, with immobilization, early controlled passive motion, and restoration of forceful activities at 10 to 12 weeks.

If the laceration is less than 60%, the injury is evaluated for the risk of triggering. If triggering is seen, the flap of tendon is smoothly debrided and the flexor sheath is repaired to help avoid entrapment or triggering of the flap in the defect in the flexor sheath. Postoperatively, the part is protected with dorsal block splinting for 6 to 8 weeks and more forceful activities are resumed gradually after approximately 8 weeks.

Zone I

The flexor digitorum profundus tendon can be repaired primarily by direct suture to its distal stump or by advancement and direct insertion into the distal phalanx when the distance is 1 cm or less. Extreme care should be exercised when advancing a flexor profundus tendon. The 1-cm rule regarding advancement includes the amount of tendon that is excised, the “kinking” or bunching up that may occur, and the length of tendon inserted into bone. Excessive trimming and advancement of the tendon can result in a finger that is held in a flexed position compared with other fingers (the finger “cascade”). Although the finger may function reasonably well, uneven tension can be applied to the common muscle belly of the flexor profundus tendons and can lead to limited flexion of the remaining profundus tendons (the “quadriga effect” described by Verdan). In such a situation, lengthening of the tendon at the wrist should be considered or, if excessive shortening has occurred, tendon grafting may be considered.

A pull-out wire technique can be used to attach the proximal tendon end to its distal stump (see Fig. 66.27 ) or directly to the bone after advancement (see Fig. 66.26 ). When the diagnosis of interruption of this tendon is delayed, and the tendon has retracted into the palm, its vinculum has been disrupted and a decision must be made regarding repair. Three types of flexor tendon ruptures have been described, depending on the level to which the tendon has retracted. In type 1, the tendon is found retracted into the palm. If it is within 7 to 10 days of the injury, the tendon should be threaded back into the finger and reattached with a pull-out wire into the distal phalanx. In type 2 ruptures, the tendon has retracted to the level of the proximal interphalangeal joint. At times, despite the passage of a few months, these tendons can be reattached as well. In type 3, the tendon has retracted only to the level of the distal interphalangeal joint and usually has a bony fragment attached to it. These also usually can be treated by reattachment. Although satisfactory function can be achieved, limitation of distal interphalangeal joint motion is to be expected, regardless of the level of rupture.

Old, untreated injuries to the flexor profundus in zone I can be treated by tendon grafting, tenodesis, or arthrodesis of the distal joint, depending on the finger involved and the age and needs of the patient. Flexor tendon grafting in such situations in the presence of an intact and functioning sublimis tendon has been recommended for the index and long fingers in specific situations.

All authors recommend careful patient selection: highly motivated patients between 10 and 21 years old may be considered candidates for grafting. The flexor profundus of the ring finger can be grafted after tendon injuries in zone I for specific needs (e.g., skilled technicians, musicians). Because of the risk of damaging the intact flexor sublimis and the additional potential complications of flexor tendon grafting, patients who are older, who have joint stiffness, who are noncompliant, or who do not understand the difficulty in achieving a successful result should not be considered for flexor tendon grafting. Some authors pass the tendon graft around the sublimis tendon. Two-stage tendon grafting also has been advocated.

Zone II

Primary repair of flexor tendons in the fibroosseous sheath (Bunnell’s “no man’s land”), which was controversial until the major contributions of Verdan and of Kleinert, is now widely accepted. If repair is done under satisfactory conditions by an experienced surgeon, satisfactory function can be expected in 80% or more of patients. Generally, the results of flexor tendon repair are better in younger patients than in patients older than 40 years of age. The results of primary flexor tendon repair also are better than secondary repair or staged reconstruction with a graft. Here especially, the primary surgeon has the greatest influence on the final result. To make the decision and perform a primary repair, a surgeon should be sufficiently skilled to perform a tendon graft or tenolysis later if the primary repair fails.

Primary repairs at this level frequently fail because of adhesions in the area of the pulleys. Exacting wound care is crucial. If the timing of tendon repair is in doubt, the wound should be cleaned and the repair made later by an experienced surgeon.

Technical concerns during the repair procedure include the management of lacerations of the profundus and sublimis tendons, the appropriate orientation of the profundus with the sublimis slips, the attachment of the sublimis slips in the thin flat area, the management of the flexor sheath, including the annular thickening (pulleys), the postoperative management, and the timing and technique for tenolysis. Most surgeons recommend repair of the flexor profundus and sublimis tendons in zone II. Care should be taken when the flexor sublimis has been injured in the area just proximal to the proximal interphalangeal joint and distally where the orientation of the proximal and distal portions of the tendon can be misinterpreted and repairs may be incorrectly done with the sublimis slips malrotated ( Fig. 66.32 ). A report in the literature noted that a portion of the A2 pulley can be incised to improve tendon gliding, and all of A2 can be incised if the remainder of the sheath and pulleys is intact. Care also should be taken to deliver the flexor profundus tendon through the split portion of the flexor sublimis when the profundus tendon has retracted proximally ( Fig. 66.33 ).

As indicated previously, many suture configurations have been advocated. In zone II, a core suture with four or more strands, locking components, and buried knots is usually preferred. The educational and clinical experience of the surgeon and the particular demands of each case may allow the use of other appropriate techniques. Traditionally, it has been recommended that the intratendinous configuration of the core sutures should remain in the volar third of the tendon to avoid impairment of the intratendinous circulation. Placing sutures in the dorsal half of the tendon was found to provide a mean strength to the repair that was 58% greater than for sutures placed in the volar half of the tendon. A running, circumferential 5-0 or 6-0 nylon is used by most surgeons to complete a smooth repair and to minimize adhesion formation to the sheath and “triggering” on the sheath. A peripheral suture increases the strength of the repair, and a four-strand core suture combined with a peripheral suture allows a postoperative routine of light active flexion with the wrist extended, leading to better function and fewer complications. The choice of suture material depends on the experience and preference of the individual surgeon; however, most authors prefer a synthetic braided suture, usually of polyester material (Mersilene, Ticron, Tevdek, FiberWire), whereas others have had success with monofilament nylon and wire suture. Usually 3-0 or 4-0 sutures are required. Generally, a pull-out suture technique is unnecessary in zone II. The postoperative management is paramount, as discussed subsequently (see “Primary Suture of Flexor Tendons”).

Tenolysis may be required in an estimated 18% to 25% of patients after flexor tendon repair. Usually, tenolysis is considered when the patient has reached a plateau in postoperative rehabilitation and when all wounds are supple and flexible and the skin is soft with minimal or no induration around the scars. Fracture and joint injuries should be healed, and there should be no or minimal residual joint contractures. A near-normal passive range of motion is preferred. Normal sensation is preferred; however, if digital nerves have been repaired, progress toward return of sensation should be observed. For these criteria to be met usually requires 5 to 6 months after the tendon repair. Three months is considered to be the earliest time for flexor tenolysis, assuming no improvement in motion in the previous 1 to 2 months. Flexor tenolysis is a technically demanding procedure and should be undertaken by someone who has training and experience in this type of surgery. Function in the finger can be improved by 50% by tenolysis (see also “Flexor Tendon Injuries in Children”).

Zone III

At zone III, the muscle bellies of the lumbricals and the tendons frequently are interrupted. Additional incisions often are needed to expose this area further. All tendons can be repaired primarily if wound conditions are satisfactory or if repair is delayed only a few days. If conditions permit, primary repair of sharply severed nerves is crucial because delaying the repair even a few weeks results in significant gaps between the nerve ends. If wound conditions preclude tendon and nerve repair, the ends of the tendons and nerves are sutured to adjacent fascia to prevent undue retraction. Lumbrical muscle bellies usually are not sutured because this can increase the tension of these muscles and result in a “lumbrical plus” finger (paradoxic proximal interphalangeal extension on attempted active finger flexion).

Zone IV

All tendons and nerves in zone IV can be repaired primarily when wound conditions are satisfactory; however, for exposure it may be necessary to release partially or completely the transverse carpal ligament. Should complete release be necessary, the wrist should not be placed in flexion past neutral position, but the fingers should be brought into slightly more flexion than usual to permit relaxation of the musculotendinous units. Flexion of the wrist beyond neutral may permit subluxation of the repaired tendons out of their normal bed and then bowstringing them just under the sutured skin. When it is technically possible to accomplish tendon repair and retain part of the transverse carpal ligament, this problem is eliminated. Alternatively, the transverse carpal ligament can be released in a Z-lengthening configuration, allowing its repair after tendon repair and providing a pulley for the tendons. The flexor digitorum profundus tendons at this level may not be distinctly separated, and frequent interdigitations may be present.

Zone V

Because zone V is proximal to the transverse carpal ligament, tendon gliding after repair usually is better here than in more distal zones. All tendons and nerves lacerated in this area should be repaired primarily when wound conditions are satisfactory, as advised earlier. The chief difficulty of repair here usually is one of exposure, which requires a proximal extension and possibly a distal extension of the typical transverse laceration. Blood clots within the tenosynovium usually serve as clues to locating severed tendons. At this level, the profundus tendons are not completely separated into individual tendon units. The sublimis tendons usually are distinctly separated, their muscle bellies extend more distally, and the severed ends usually are more easily matched. If the necessary expertise is unavailable, primary repair can be delayed and the wound cleaned. Results are not likely to be compromised by a brief delay of several days. At this level, excision of some of the tenosynovial covering is necessary to identify and remove the hematoma; however, a total synovectomy usually is not indicated. An isolated laceration of the palmaris longus tendon does not absolutely require repair.

Delayed repair of acute injuries

Delayed repair in any zone may be necessary in the presence of severe wound contamination, crushing or avulsing injuries, soft-tissue loss, multiple comminuted fractures, or lack of available surgical skill. Delayed repairs of tendons are reasonable also if other injuries require immediate surgery. In such circumstances, a patient’s condition might not permit definitive management of tendons and nerves, and it is appropriate to clean the limb as well as possible and loosely close the wound or leave it open but covered with a sterile bandage and splint. Plans should be made for definitive management of the wound and injured structures. Undue complications usually are not encountered if the repair of tendons is delayed for 2 to 3 days as long as the wound has been thoroughly cleaned. Prolonged delay may permit unacceptable retraction of tendons and nerves, especially in zones III, IV, and V. If it seems that definitive management of the tendons and nerves may be delayed, an attempt should be made to secure the ends of the tendons and nerves to the adjacent soft tissues to prevent retraction before achieving satisfactory wound closure.

Primary suture of flexor tendons

The preparations and techniques for primary and delayed primary suture of flexor tendons vary from zone to zone. The techniques are discussed according to the requirements of each zone. Generally, further exposure of the tendon to be sutured may be necessary. Additional incisions ( Fig. 66.34 ) should be made without crossing flexion creases at a right angle. Usually, less exposure is needed distally than proximally because the distal segment of the tendon may be delivered into the wound by flexing the distal joints. Also, the distal segment is not subject to retraction by muscle, as are the proximal segments. Regardless of the zone in which the tendon is injured, careful attention should be given to the anatomic location of the respective tendons and their relationships to each other and other structures. Meticulous, gentle, and atraumatic technique should be used in the handling of the tendons. Each tendon is delivered by grasping it with a small-tipped forceps with teeth. Crushing of the cut surface of the tendon with instruments such as Allis forceps, Kocher clamps, and hemostats should be avoided. Although the tip of the tendon can be held with a small hemostat, the crushed portion should be excised before the suture is tied. Sometimes this can shorten the tendon needlessly. Suturing techniques should be exact so that the tendon ends are held together accurately and distraction, gap formation, and exposure of raw surfaces at the junction are avoided.

Repair in Zones III, IV, and V

Technique 66.11

zone III

• ▪

  In zone III, the area between the distal edge of the transverse carpal ligament and the proximal portion of the A1 pulley, perform flexor tendon repair in a manner similar to zone II repair. Incisions that extend the wound proximally and distally may be required. Avoid crossing flexion creases at right angles. Also avoid injuring neurovascular structures and devascularizing the skin flaps.

• ▪

  Achieve proper orientation of the tendon before repair. At times, if tendons have retracted into the carpal tunnel or more proximally, partial release of the transverse carpal ligament may be required to deliver them distally into the palm.

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  Although the flexor sheath is not involved in the palm, use careful technique in the placement of sutures; it probably is best to use an intratendinous core suture in the palm to avoid exposure of the suture material to adjacent structures. Satisfactory healing and functional results can be expected after repair of the tendons in the palm.

• ▪

  Apply a compressive, bulky dressing and immobilize the thumb, fingers, and wrist. Immobilize the wrist at about 45 degrees of flexion, with the fingers at about 50 to 60 degrees of flexion and the interphalangeal joints extended.

Zone IV

• ▪

  In zone IV, the area of the carpal tunnel, an injury directly to the base of the palm usually also involves the median nerve. If a laceration occurs just proximal to the wrist flexion crease, flexor tendon injury, especially with the fingers flexed, in zone IV should be suspected.

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  Extend the laceration distally into the palm and proximally into the forearm, taking care to cross flexion creases obliquely. If the laceration occurs beneath the transverse carpal ligament, partial or complete release of the transverse carpal ligament may be required.

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  Preserve, if possible, a portion of the transverse carpal ligament to avoid bowstringing postoperatively.

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  If it cannot be preserved, release it in a Z-lengthening configuration so that it can be repaired and help minimize the risk of postoperative bowstringing.

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  Repair the flexor profundus and sublimis tendons in the carpal tunnel; probably the best suture configuration is an intratendinous one with a locking core suture to hold the tendons with minimal exposure of cut surface and suture material.

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  In the carpal tunnel, ensure proper orientation and location of the individual tendons. The usual arrangement of the flexor sublimis tendons in the carpal tunnel, with the middle and ring finger tendons superficial to the index and small finger tendons, is helpful to recall in this situation. Partial tenosynovectomy may be required to diminish the bulky and edematous tissue that may follow the repair.

• ▪

  Close the skin with 4-0 nylon and apply the bandage and dorsal splint to maintain the wrist in approximately 45 degrees of flexion.

• ▪

  If the transverse carpal ligament has been completely released and repair is impossible, bring the wrist nearly to neutral and flex the fingers more acutely to diminish pressure on the volar skin and to minimize bowstringing.

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  If the transverse carpal ligament is partially intact or has been repaired, immobilize the wrist in about 45 degrees of flexion, with the fingers in 50 to 60 degrees of flexion at the metacarpophalangeal joints and the interphalangeal joints in full extension.

Zone V

• ▪

  In zone V, the volar forearm proximal to the transverse carpal ligament, multiple tendons, nerves, and vessels frequently are injured by major lacerations, often from broken glass or in violent altercations with knives. In this area, it is important to identify the tendons accurately.

• ▪

  Because of their common muscle origin, when the sublimis and profundus tendons are divided, particularly at the wrist, they can be delivered into the wound as a group by finding and pulling distally on one tendon.

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  Properly match the tendon ends by careful attention to their location and level in the wound, their relation to neighboring structures, their diameters, the shape of their cross sections, and the angle of the cuts through each tendon. Although it is not a disgrace to open an anatomy book in the operating room to be certain of anatomic relationships, it is inexcusable to sew the median nerve to the flexor pollicis longus, the palmaris longus, or some other tendon.

• ▪

  The proximal and distal ends of the median nerve usually can be identified easily in their appropriate anatomic location and from their more yellowish color and the presence of a volar midline vessel and the nerve fascicles, which usually can be identified in the median nerve’s severed ends.

• ▪

  Although 4-0 sutures usually are used in the palm and more distally, 3-0 nylon may be sufficient for suturing tendons in the distal forearm. Repairs done in the distal forearm do not absolutely require an intratendinous repair. A double right-angled or mattress suture may be satisfactory in the forearm.

• ▪

  Repair nerves and vessels if needed after the tendon repairs in the forearm, working from the repair of deep structures to more superficial structures.

• ▪

  Close the wounds with 4-0 nylon and immobilize the limb with the wrist flexed approximately 45 degrees and the metacarpophalangeal joints flexed 50 to 60 degrees with the interphalangeal joints in full extension.

Postoperative Care

Excellent results can be achieved using either of two postoperative mobilization techniques. In one (Kleinert), active finger extension is used with passive flexion achieved using a rubber band attached to the fingernail and at the wrist ( Fig. 66.37 ). This subsequently has been modified with a roller in the palm to alter the line of force of the rubber band. The second technique (Duran) involves a controlled passive motion technique with dorsal blocking of the fingers ( Fig. 66.38 ). The margin of safety with early passive motion rehabilitation is increased if the tendon repairs have been done with the stronger multistrand techniques (four or more). Multistrand repairs are used if an early active motion program is considered. Children younger than approximately 10 years old and noncompliant patients cannot be entrusted with understanding and following the complexities of either of these techniques, and a more conservative postoperative management routine should be selected, depending on the judgment of the surgeon and the therapist.

Although some patients may be allowed to remove a splint in the first week after surgery, we have found it safer to leave the nonremovable postoperative dorsal splint in place. Passive flexion and extension of the proximal and distal interphalangeal joints are demonstrated in the first postoperative day. The wrist usually is positioned in 20 to 45 degrees of flexion with the metacarpophalangeal joints in 50 to 70 degrees of flexion and interphalangeal joints left in the neutral position. Before closure of the wound, the amount of passive movement of the fingertip required to create a 3- to 5-mm excursion of the tendon is determined ( Fig. 66.39 ). This amount of movement is started the day after surgery. A removable splint can be used 3 days after surgery in some compliant patients ( Fig. 66.40 ). The patient is instructed in an exercise program, including eight repetitions of proximal and distal interphalangeal and composite passive flexion and extension of the joints twice daily. A “place and hold” exercise can be added for compliant patients if a strong multistrand repair has been done. This is continued for at least 3 to 4 weeks, at which time a removable splint can be applied.

The controlled active motion program requires the attachment of a suture through the tip of the fingernail or a garment hook glued to the nail allowing the attachment of an elastic band (see Fig. 66.37A ). A dorsal splint holds the wrist in 20 to 30 degrees of flexion and the metacarpophalangeal joints at 40 to 60 degrees. The interphalangeal joints are splinted in extension. The rubber band is passed beneath a roller or a safety pin in the palm and is secured to another safety pin at the level of the distal forearm (see Fig. 66.37B ). The safety pin maintains the finger in flexion of 40 to 60 degrees at the proximal interphalangeal joint with no tension on the rubber band. The rubber band should allow full extension of the proximal interphalangeal joint against the traction of the rubber band. With this form of controlled mobilization, it is believed that the flexor tendon repair is not stretched and the movement that is allowed can enhance healing. Beginning on the first day after surgery, active extension exercises within the limitations of the splint are encouraged. If the patient does not seem able to understand and cooperate with this technique, it should be abandoned in the first week.

After 3 weeks, the dorsal splint is removed and a wrist band with a hook for the rubber band is used for an additional 3 weeks. The patient actively extends the digit against the resistance of the rubber band. No passive extension or active flexion is permitted. The wrist band splint is discontinued at 6 to 8 weeks, and dynamic extension splinting is used to prevent contractures of the proximal interphalangeal joint. At 8 to 10 weeks, strengthening exercises are permitted, and the patient progresses to using the hand normally at 10 to 12 weeks after the repair.

Treatment

Direct repair, tendon grafting, or tendon transfer has been recommended for the treatment of these injuries. Factors found to influence the treatment and outcome are (1) the length of time between injury and treatment, (2) the extent to which the tendon retracts, (3) the blood supply to the avulsed tendon, and (4) the presence of bony fragments seen on a radiograph. These factors allow the classification of these injuries into three types. In type 1, the tendon retracts completely into the palm and is held there by the lumbrical origin. In type 2, the tendon retracts to the level of the proximal interphalangeal joint with a long vinculum intact, presumably maintaining blood supply. In type 3, usually a bony fragment is involved. The fragment may be comminuted or noncomminuted and may be nonarticular or intraarticular.

For type 1 injuries, reinsertion into the distal phalanx is recommended if the injury is detected within 7 to 10 days. After this period, the distal end of the tendon likely has become kinked and softened, prohibiting delivery into the finger and attachment to the distal phalanx. A midlateral or volar oblique incision usually is used. The sheath is opened through a transverse incision distal to the A2 pulley. Absence of the tendon end in this area indicates retraction into the palm. A transverse incision near the distal palmar crease exposes the flexor sheath proximal to the A1 pulley and allows location of the tendon end, which can be delivered by a variety of techniques using sutures, the retrograde passage of pediatric feeding tubing or intravenous tubing, or wire loops to allow antegrade passage of the tendon without additional injury to the tendon sheath. The tendon is attached to the distal phalanx with a pull-out wire, preferably of the antegrade type rather than the traditional retrograde Bunnell pull-out wire (see Fig. 66.27 ). This is left in place for 3 to 4 weeks, during which time the limb is immobilized in a dorsal splint with the wrist in flexion, the metacarpophalangeal joint in 70 to 80 degrees of flexion, and the interphalangeal joints in extension. The pull-out wire is removed at 3 to 4 weeks. If a type 1 injury is seen late, consideration should be given to flexor tendon grafting in a young, cooperative patient for the index, long, or ring finger, or, as alternatives, tenodesis or arthrodesis should be considered, depending on the needs and activities of the patient.

Type 2 injuries with the tendon retracted to the level of the proximal interphalangeal joint can be repaired at a later time than injuries in which the tendon is retracted into the palm, because the circulation is thought to be maintained. Some of these avulsions have been satisfactorily repaired several months after injury.

Type 3 injuries with an avulsion fracture close to the level of the distal interphalangeal joint also can be treated by fracture fixation at a later time because of the preservation of the circulation. Early passive motion is encouraged with the finger immobilized, and if a pull-out wire technique is used, the aforementioned postoperative treatment is followed. A word of caution with types 2 and 3 injuries, however: the tendon can be avulsed from the bony fragments and are then treated as type 1 injuries.

In many patients seen late, regardless of the level of retraction, if satisfactory reattachment is impossible, consideration should be given to arthrodesis or tenodesis. A select group of motivated patients in the 10- to 20-year age range may achieve satisfactory function after flexor tendon grafts through the intact sublimis tendon in the index and long (middle) fingers.

Postrepair rupture

If flexor tendon rupture after a primary repair is detected promptly, satisfactory results can be achieved if the finger is explored and the ruptured tendon is located and repaired. If detection of the rupture is delayed, end-to-end repair rarely is possible and tendon graft reconstruction may be required. The flexor tendon can rupture after tenolysis. In these situations, judgment is required in making the decision regarding exploration and repair versus tendon grafting. If the tendon has ruptured in a densely scarred area, satisfactory function after reexploration and repair is unlikely and consideration should be given to delayed tendon grafting. When a rupture of the flexor pollicis longus tendon is seen early, the tendon can be reattached to the distal phalanx; when seen late, a tendon graft may be necessary because of muscle shortening and tendon degeneration (see Technique 66.16).

Zone I

When the long flexor tendon of the thumb is divided in zone I within 1 cm of its insertion, it can be sutured primarily to the distal stump or advanced and sutured directly into the bone. Some of the flexor sheath may require division. When this tendon is transected more proximally than 1 cm from its insertion, further advancement becomes necessary and lengthening of the tendon by Z-plasty just proximal to the wrist should be done. This tendon is unique in that it can be advanced without disturbing its blood supply because it does not have a vinculum. Tendon advancement rather than tendon grafting has been recommended because paratendinous adhesions are not as likely to form after advancement.

Zone II

In zone II, the critical pulley area at the thumb metacarpophalangeal joint, a portion of the pulley can be excised to lessen the possibility of adherence to the pulley of the site of the tendon suture. Primary repair is unpredictable, however, and a later graft might be the better choice, unless the surgeon is experienced in tendon repair. Advancement of the tendon distally to be sutured to a stump that is shortened to lie distal to the metacarpophalangeal pulley has the advantage of moving the repair site from beneath the area of a pulley. Lengthening of the tendon at the wrist by Z-plasty also may be required for this procedure. Urbaniak recommended an end-weave repair at the site of lengthening just proximal to the wrist.

Zone III

In zone III, with a laceration of the flexor pollicis longus tendon, the proximal end frequently retracts to near the wrist level. Usually the proximal end can be retrieved easily with atraumatic grasping of the tendon end in the sheath. If the tendon end cannot be retrieved easily, persistent grasping and probing should be avoided, and the tendon can be located through a separate incision at the wrist, between the radial artery and the flexor carpi radialis. Primary repairs in this zone can be performed when the two ends are retrieved and apposed by flexing the wrist and the distal joint of the thumb. When retrieval of the proximal tendon requires an additional incision at the wrist, the tendon should be carefully rethreaded through its normal route. This can be done by inserting a 22-gauge wire loop, a suture passer, or a tendon carrier through the sheath from the distal end, delivering a suture attached to the tendon, and threading it through from proximal to distal.

Zone IV

In zone IV, the tendon rarely is cut because it is protected in part by a shelf of the radiocarpal bones. There is no contraindication to repair at this level as long as the repair technique is atraumatic and the two ends are recoverable. The creation of a lump of suture material sufficient to cause median nerve compression within the closed space of the carpal tunnel should be avoided.

Zone V

In zone V, primary repair of the flexor pollicis longus tendon is indicated. Usually the location of the tendon ends and end-to-end repair are not difficult.