Pitfalls

• Avoid excessive tendon handling during mobilization and repair.

• Avoid disrupting pulley system, especially A2 and A4.

• Avoid intruding or interfering with tendon vascularity.

Diagnostic Studies

Anteroposterior and lateral radiographs of the injured hand or forearm should be evaluated to ensure that no bony injury is overlooked and to investigate the possibility of a retained foreign body. No fracture was appreciated.

Finger Flexor Laceration
Figure 33—1. Patient's finger at presentation.

Differential Diagnosis

Laceration of both flexor digitorum superficialis and profundus and digital nerve

Laceration of either flexor tendon singularly with inability to move secondary to pain

No tendon laceration but unable to move secondary to pain

No nerve laceration but rather contused/neuropraxic

Diagnosis

Laceration of the Ring Finger Flexor Digitorum Profundus, Flexor Digitorum Superficialis, and Ulnar Digital Nerve to the Ring Finger

The repair of lacerated flexor tendons of the hand and their return to appropriate function is one of the most difficult and challenging tasks for a surgeon to undertake. Lacerations within zone 2 are especially complex. Within this area of the fibro-osseous digital canal, the profundus and superficialis tendons interweave in an intricate and close relationship. Even minimal swelling of the epitenon is sufficient to impair free motion of both tendons. The margin for error in tendon repair is thus very small in this region.

The necessity of minimizing adhesions can be a daunting charge. On the one hand, it requires nontraumatic treatment of the tendon, respecting the dorsally located blood support and, on the other, requires early motion, jeopardizing the continuity of sutures. This patient's flexor tendons were repaired using a Tajimi technique with four strands of 4—0 polyester crossing the repair. Care was taken to avoid excessive handling of the tendons, with the tendon being grasped by forceps only once. Additionally, a 6—0 Prolene running epitendinous suture was used to minimize gapping and facilitate healing. The sheath was not repaired. No publication to date provides scientific evidence that sheath repair improves outcome. Although one may argue that reconstituting the sheath provides a barrier to adhesion formation, restores synovial fluid nutrition, and restores sheath mechanics, in practicality the synovial membranes are usually badly damaged and unsalvageable.

Gapping at the repair site results in weakening and, potentially, adhesion formation. Each increase in suture caliber strengthens the repair, nevertheless, at the cost of additional material interference. This additional material may compromise tendon vascularity and/or precipitate adhesion formation. Biomechanically, core sutures placed dorsally strengthen the repair; yet there is a fine line, as sutures placed too dorsal may compromise the tendon's blood supply. Early motion should be begun. Stressed tendons heal faster, gain tensile strength faster, form fewer adhesions, and demonstrate better excursions (Table 33—1).

The surgeon must feel comfortable with his or her choice of techniques and suture material. These characteristics should lend themselves to easy placement of sutures in the tendon and the ability to place secure knots, afford minimal

Table 33—1 Tensile Stress on Normally Repaired Flexor Tendons

Passive motion Light grip Strong grip

500 g 1500 g 5000 g

Tip pinch-index flexor digitorum profundus 9000 g

Table 33-2 Repair Strength with Epitendinous Suture

Two strand Four strand Six strand

0 Week

2500 g 4300 g 6000 g

1 Week

3 Weeks

6 Weeks

(+20%) 2700 g 5200 g 7200 g interference with tendon vascularity and gapping at the repair site, and provide sufficient strength throughout healing to permit the application of early motion stress to the tendon (Table 33—2).

Preoperative Management

Initially, the wound was irrigated with 1 L of normal saline. A tetanus booster was administered. The laceration was loosely closed with 4—0 nylon suture in an interrupted fashion. The hand was immobilized with a volarly placed plaster splint maintaining the wrist in 45 degrees of extension, the metacarpophalangeal (MP) joints near 90 degrees of flexion with full extension of the proximal and distal inter-phalangeal joints.

Surgical Management

The arm is exsanguinated with an Esmarch bandage and tourniquet inflated to 250 mm Hg. The use of 2 to 4 power loupe magnification greatly enhances one's proficiency in performing flexor tendon repair, and small, precise instrumentation is a prerequisite for this type of surgical repair. As is necessary with every tendon laceration repair, the wound is extended in a Bruner type fashion both proximally and distally to provide a wide visibility of the injured area. Using mid-axial extensions places the digital vessels and nerves at unnecessary risk unless a concomitant injury is suspected. The incisions are extended as needed to visualize the lacerated ends of the tendon or tendons. An adequate view of the surgical field must be created to avoid carrying out delicate surgical repairs within the confines of a small, cosmetic wound. Dissection begins midline, over the tendon sheath, and then proceeds with identification of the digital nerves and vessels. If these structures, too, have been severed, the ends are mobilized and brought into proximity for subsequent suturing.

At this point, the laceration in the tendon sheath was identified at the C1 level (between A2 and A3). A window in the cruciate-sheath system is made by carefully excising this tissue. Additional windows may be necessary depending on the level of injury and positioning of the proximal and distal stumps. These should be fashioned as needed. However, great care is taken to preserve the annular components (especially A2 and A4), which are almost impossible to adequately repair.

The distal stumps of the profundus and superficialis are delivered into the cruciate window by acutely flexing the DIP and PIP. Once the tendons are exposed in this manner, core sutures are placed in the superficialis and profundus and clamped for later usage (Fig. 33-2).

Exposed Tendon Wrist
Figure 33—2. After the tendons are exposed, core sutures are placed in the superficialis and profundus.

Retrieval of the proximal stumps may be difficult, and several techniques can facilitate their delivery into the repair site. The tendon ends may be "milked" in a proximal to distal fashion, again, with flexion, except this time at the wrist and MP joints. If not completely accessible at this point, a tendon retriever or grasper may be employed if the tendon(s) can be visualized in the sheath. The surgeon should be aware, however, that care must be taken when using this instrument, as repeated blind grasps down the tendon sheath may damage the delicate synovial lining of the pulleys and provoke adhesions. Additionally, two clever techniques may be employed. First, a skin hook may be used, as described by Morris and Martin. The hooked end is slid along the surface of the sheath until it is past the tendons, and then the hook is turned toward the tendons and pierced into the most superficial one. The instrument is pulled distally, with both tendons usually following. Second, a method described by Sourmelis and McGrouther can be used. A small catheter is passed from the distal wound into the palm (or vice versa) within the sheath. Through a midpalmar incision, the catheter is sutured to both tendons several centimeters proximal to the A1 pulley. The catheter is then pulled distally and freely delivers the tendon stumps for suturing.

Regardless of the manner of proximal retrieval, once the tendon ends are brought into the cruciate window, a 25-gauge needle is used to maintain their position without unnecessary, repeated grasping of the tendons. Core sutures can then be placed in both the superficialis and profundus proximal ends to allow juxtapositioning with the distal ends of both (Fig. 33-3). Prior to final repair, it is necessary to ensure that the proper anatomic relationship between the superficialis and profundus is restored. It is worth a second look to verify that, indeed, the proximal end of the

Camper ChiasmCamper Chiasm
Figure 33-4. The proximal end of the profundus, lying deep to Figure 33-5. Four core strands of 4-0 polyester are used in the the superficialis proximal to Camper's chiasma. repair of both the superficialis and the profundus.

profundus, lying deep to the superficialis proximal to Camper's chiasma, is matched with its distal counterpart (Fig. 33-4).

The repair of both the superficialis and profundus consisted of four core strands of 4-0 polyester (Fig. 33-5). An additional running horizontal locking stitch using 6-0 Prolene is placed in the peripheral epitendinous layer of each tendon. The flexor sheath was not repaired (Fig. 33-6).

When the repair is completed the digit must be put through a full range of motion, passively extending the DIP point. This motion will test the strength of the repair. After the completion of the repair, the lacerated digital nerve was repaired using 9-0 nylon suture. Occasionally, both digital nerves and/or one or both arteries need repair as well. The skin was closed using 4-0 nylon in an interrupted fashion. A sterile dressing minimizing pressure between the digits was utilized. The finger was splinted with the wrist in 30 degrees of flexion. The MP joint flexed 45 degrees, and near extension of the PIP and DIP joints was noted.

Postoperative Management

Understanding the healing stages of flexor tendons is helpful in guiding postoperative management. For days 1 to 3, tendon strength is equal to suture strength. From days 4 to 14, tendon strength decreases with the inflammatory response and weakening of collagen fibrils (the exudative phase). From days 15 to 28, tendon repair and strength begin to increase (the reparative phase) and passive motion helps con-

Strand Tendon Repair
Figure 33-6. A running horizontal locking stitch of 6-0 Prolene is added in the peripheral epitendinous layer of each tendon. The flexor sheath was not repaired.

vert longitudinal tensile forces to compression across the tendon-healing site. By day 28, the active phase of tendon healing is sufficiently underway to allow active motion.

The flexor repair rehabilitation program is instituted 2 to 3 days postoperatively. It has been demonstrated that delicate active flexion performed with the wrist in extension should be relatively safe for tendons repaired with a four- or six-strand core suture technique enhanced by a strong running-locking epitendinous suture. This was the case with this patient's repair. The program begins with the therapist instructing him to first passively flex all three long finger joints (MP, PIP, and DIP) while the wrist is maintained in flexion. Then, with the assistance of the therapist, he actively extends his wrist while maintaining or holding his digit in the flexed position. A resting splint is fashioned similar to a traditional dorsal blocking splint that positions the wrist in 30 degrees of palmar flexion, the MP joint in 45 degrees of flexion, and the interphalangeal joints in neutral. The splint is removed during therapy to allow assisted "place and hold" exercises.

This protocol is followed for 4 weeks with individual adjustments made depending on the specific problems the patient may encounter, such as excessive pain, swelling, or joint stiffness. After 4 weeks, the repaired tendons should have regained sufficient strength to allow for progression or advancement of therapeutic modalities. Thus, at 4 weeks, active flexion and extension exercises of the digits and wrist are instituted with light muscle contraction. The patient is advised not to extend both the wrist and finger(s) simultaneously. The program continues to emphasize the "place and hold" technique incorporating passive digital flexion with the wrist flexed, followed by active maintenance of the flexion while the wrist is extended. Thereafter, the patient drops the wrist into flexion and extends the digit(s) to commence the tenodesis effect. The dorsal block splint is worn between exercise sessions.

At 5 to 6 weeks, more vigorous exercises are permitted involving blocking exercises, isolated tendon excursion activities, and passive extension exercises. A strengthening program is begun at 8 weeks in a gradual, progressive manner. It should be emphasized that this protocol is not for everyone. Additionally, great success relies heavily on a well-trained therapist who thoroughly understands the rationale for an early motion rehabilitation program and its potential pitfalls.

Alternative Methods of Management

In the event of tendon lacerations, nonoperative management is a less likely alternative. The consequences would result in the patient's digit and hand being disabled. Options at that point are still not desirable. The patient would be left with permanent dysfunction or would have to choose surgical intervention. Yet at a later date the patient's options may be more limited, such as tendon reconstruction or surgical amputation of the affected digit(s).

Complications

Disruption of one or both flexor tendon repairs is a distressing complication. It may happen during therapy, subsequent to inadvertent strong gripping or lifting, or while a patient is asleep. Repaired tendons usually rupture through the suture material itself or through the knot. Ruptures, in cases after four-strand repairs, have been infrequent and generally are related to overzealous use of the injured hand because exemplary early motion fosters overconfidence in the strength of the healing tendon. If this does occur, the favored management is prompt reexploration and repeated repair.

Reportedly, the most frequent late complication following an early mobilization protocol is development of flexion contractures at the PIP or DIP joints or both. Prompt recognition of the difficulty permits modification of the therapy program to allow greater extension along with judicious use of dynamic splints, which may help to avoid or overcome these deformities before they progress too far.

The aim of all surgical intentions is return to full function and digital range of motion. Only meticulous technique, minimal operative trauma, and precise anastomosis will result in the restoration of the tendon's gliding function and optimal range of motion.

Suggested Readings

Bunnell S. Repair of tendons in the fingers. Surg Gynecol Obstet 1922;35:88-97.

May EJ, Silverskiold KL, Sollerman CH. Controlled mobilization after flexor tendon repair in Zone II: A prospective comparison of three methods. J Hand Surg [Am] 1992;17A:942-952.

Morris RJ, Martin DL. The use of skin hooks and hypodermic needles in tendon surgery. J Hand Surg [Am] 1993;18B:33-34.

Sourmelis SG, McGrouther DA. Retrieval of the retracted flexor tendon. J Hand Surg [Am] 1987;12B:109-111.

Strickland JW, ed. Flexor tendon repair—Indiana method. Indiana Hand Center Newsletter 1993;1:1-19.

Strickland JW. Results of flexor tendon surgery in zone II. Hand Clin 1985;1: 167-179.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment