Kevin J. Malone and Thomas Trumble
DEFINITION
Staged flexor tendon reconstruction is required in the settings of delayed diagnosis of a flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) disruption or failed previous attempt at primary repair within zone II of the digital tendon sheath.
During the first stage of the reconstruction process, a silicone rod is placed within the flexor tendon sheath. The role of this implant is to help re-establish a frictionless inner lining of the sheath that will accommodate the placement of a tendon graft in the second stage.
ANATOMY
Flexor tendons can be divided into five zones (FIG 1A).
Bunnell originally described the region between the A1 pulley and the FDS insertion, zone II, as “no man’s land” because the initial results after attempted primary tendon repair were so poor he felt that no one should attempt this procedure.
In the limited confines of zone II the two flexor tendons function together and rely on the digital sheath and its frictionless synovial interface for gliding and proper function.
Another complicating anatomic characteristic of zone II is the chiasm of Camper. Here FDP passes through the slips of FDS, creating another potential region for adhesions (FIG 1B).
PATHOGENESIS
Zone II has the highest probability of developing adhesions and the poorest prognosis after repair.
Violation of the sheath, the lining, or the blood supply to the tendons by trauma or infection may lead to dense scar and adhesion formation and can compromise the results after either a primary repair or an attempt at single-stage reconstruction with a tendon graft.
NATURAL HISTORY
Flexor tendon injuries that are not reconstructed can progress to a stiff and sometimes painful digit.
If both tendons are not functional, no active proximal (PIP) or distal (DIP) interphalangeal motion will be possible, but if only the FDP tendon is disrupted, active PIP flexion will be present.
If a digit with incompetent flexor tendons is subjected to repeated extension stress, as in pinch, the volar supporting structures will become lax over time, leading to hyperextension and an unstable joint.
PATIENT HISTORY AND PHYSICAL FINDINGS
The examiner should elicit information about the initial injury, such as when it occurred and if there were associated injuries (fractures, laceration of digital nerves or vessels).
FIG 1 • A. The five flexor tendon zones of injury. B. The decussation of the flexor digitorum sublimus produces the chiasm of Camper. Both the flexor digitorum sublimus and flexor digitorum profundus receive their blood supply via the vinculum longus and brevis.
The examiner should determine when the patient first noticed a decrease in the function of the digit (if flexor tendon repair has already been attempted).
Staged flexor tendon reconstruction is contraindicated in the setting of an active infection, and for that reason an infection history must be sought.
If an infection is identified, it should be treated aggressively with antibiotics and débridement to minimize the destruction of the flexor tendon sheath from the inflammatory process.
Tests for tendon function include:
Finger cascade: Loss of the normal cascade suggests disruption or loss of function of the flexor tendons.
FDP examination: Loss of active DIP flexion suggests disruption or loss of FDP function.
FDS examination: Loss of active PIP flexion suggests disruption or loss of FDS function.
Tenodesis effect: Loss of the tenodesis effect suggests disruption of the flexor tendons.
It is also important to assess the vascular supply and the digital sensation to determine if there is a concomitant injury to the digital neurovascular structures.
Both active and passive range of motion must be recorded for the metacarpophalangeal (MP), PIP, and DIP joints.
If contractures are present, as evidenced by decreased passive joint motion, intensive therapy should be initiated before proceeding with staged flexor tendon reconstruction.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Radiographs should be obtained to rule out fractures or other associated injuries to the hand and digits.
Ultrasound or MRI can be used to help localize the site of tendon rupture and position of the proximal stump if not clear by clinical examination.
DIFFERENTIAL DIAGNOSIS
Fracture or dislocation of digits
Proximal compression of anterior interosseous nerve, median nerve, or ulnar nerve
Cervical radiculopathy
Upper motor neuron lesion
NONOPERATIVE MANAGEMENT
There is no acceptable nonoperative management for combined FDS and FDP tendon lacerations. Alternatives to staged flexor tendon reconstruction include arthrodesis and amputation.
Isolated chronic disruption of the FDP tendon with an intact FDS tendon is best treated nonoperatively. Attempts at reconstruction of the FDP tendon risk function of the FDS tendon.
Buddy taping or trapping of the injured finger by an adjacent figure during finger flexion may allow concealment of the functional deficit between stage 1 and stage 2 or in the patient who is not a candidate for staged-tendon reconstruction.
SURGICAL MANAGEMENT
Indications for two-stage flexor tendon reconstruction include:
Loss of FDP and FDS
Protective sensation
Nearly full passive range of motion
Good quality skin in the region of zone II
A cooperative patient willing to participate fully in rehabilitation
The patient will need to have access to a good hand therapist before and after each of the stages of this complex reconstructive process.
Preoperative Planning
For the second stage of the procedure a tendon must be harvested to use for the reconstruction. Often, a palmaris longus graft is used. If the patient does not have a palmaris longus, then a long toe extensor or plantaris tendon can be used. In this situation, the lower extremity must also be prepared out into the surgical field.
Positioning
For both stages of the procedure the patient is placed supine on the operating table with the arm abducted on a hand table. A nonsterile tourniquet is placed around the upper arm for hemostasis.
Approach
Stage 1: A volar Brunner incision is made over the flexor tendon sheath and extended proximally into the palm. A second incision is made in the distal forearm to ensure placement of the rod within the carpal tunnel.
Stage 2: A limited Brunner incision is made at the level of the distal junction of the repair. A separate incision is made at the level of the proximal junction of the repair. This can be the same incision in the distal forearm as in stage 1 if the tendon graft is long enough. Alternatively, the proximal junction will be in the palm with shorter tendon grafts. A third incision or set of incisions will be made for the tendon harvest.
TECHNIQUES
STAGE 1
A volar Brunner incision is made over the course of the flexor tendons.
The flexor tendon sheath is incised, taking care to preserve the A2 and A4 pulleys. L-shaped flaps can be made within the flexor sheath to aid in access to the flexor tendons and protect the A2 and A4 pulleys (TECH FIG 1A).
The scarred tendon is excised, leaving a portion of the distal stump of the FDP intact at its insertion.
This is useful in securing the tendon rod in stage 1 and the tendon graft in stage 2.
If a digital nerve laceration is identified, it should be repaired at this stage.
Release any adhesions within the sheath.
Release any flexion contractures of the joints by releasing the volar plate and accessory collateral ligaments.
Be sure to preserve the proper collateral ligaments.
If the A2 or A4 pulleys are absent or have been excised with the scar release, they need to be reconstructed. A tendon graft can be used to reconstruct the pulleys (TECH FIG 1B).
TECH FIG 1 • A. Creating a L-shaped flap can aid in accessing the underlying flexor sheath contents while preserving the important A2 and A4 pulleys. B. Tendon weaves for reconstruction of A2 and A4 pulleys. C. A “passive” silicone implant running under A2 and A4 pulleys is secured distally to the flexor digitorum profundus stump and extends proximally to the distal forearm.
The tendon should be passed between the proximal phalanx and the extensor tendon for A2 reconstruction.
For A4 reconstruction, the tendon can be passed dorsal to the extensor tendon.
A silicone Hunter rod is inserted into the sheath. Distally, it is secured to the remnant of the FDP tendon with nonabsorbing suture.
If there is not enough of the tendon remnant, it can be secured to surrounding tissue at the base of the distal phalanx.
Some Hunter rods can be secured using a screw placed in the distal phalanx.
Proximally, the silicone rod is passed through the carpal tunnel and allowed to glide free with the flexor tendons in the distal forearm (TECH FIG 1C).
All skin incisions are closed with 4-0 nylon after ensuring hemostasis.
The patient is then placed into a dorsal blocking splint holding the fingers into an intrinsic plus posture.
Rehabilitation is started early after surgery, often within 1 week, to ensure that the patient regains full passive range of motion. The scar tissue must be soft and supple before the patient is scheduled for the second stage of tendon reconstruction. On average this takes 3 months.
STAGE 2
Incisions and Graft Harvest
A limited Brunner incision is made distally at the level of the DIP joint so that the distal FDP stump can be located within the sheath. The sutures securing the silicone rod to the profundus stump are released.
Do not extend the incision or dissection into zone II, as this will compromise the re-established tendon sheath that has been created by the body’s reaction to the silicone rod.
A second incision is made in the distal forearm so that the proximal portion of the silicone rod can be localized.
A third set of incisions is then made for tendon graft harvest. This is typically from the palmaris longus, long toe extensor, or plantaris tendon (TECH FIG 2).
Plantaris often makes the best donor if a long segment of tendon is needed.
Graft Placement
The tendon graft is then sutured to the proximal end of the silicone rod. The silicone rod is then retrieved from the distal wound, pulling the tendon graft into the tendon sheath (TECH FIG 3A).
The distal end of the tendon graft is secured to the distal phalanx with bone anchors. The anchors should be inserted in the footprint of the FDP stump and angled slightly proximally. The proximal angle will ensure that the anchor stays within the bone rather than penetrating the dorsal cortex. It is important to ensure that the anchor does not penetrate the DIP.
Alternatively, the tendon graft can be secured to the distal phalanx with a pullout suture tied over the nail, as in a zone I flexor tendon repair. This has been associated with deformities to the nail after suture removal and has no proven biomechanical advantage over suture anchors.
Additional fixation can be provided by using the remaining FDP stump and securing this to the tendon graft with a nonabsorbable suture in figure 8 fashion.
The distal incision is closed at this point. It will become difficult to gain access to this incision after graft tension is set.
TECH FIG 2 • A. Technique for harvesting palmaris longus tendon graft. B. Technique for harvesting long toe extensor tendon graft. C. Technique for harvesting plantaris tendon graft.
TECH FIG 3 • A. Technique for using the silicone rod to draw the tendon graft into the flexor tendon sheath and out through the distal incision. B. Re-creation of the normal finger cascade. C. A Pulvertaft weave is used for the proximal junction between the tendon graft and the flexor digitorum profundus or superficialis in the forearm.
Tendon graft tension is set from the proximal wound. The correct amount of tension is determined with the wrist in a neutral posture and is set by evaluating digital flexion cascade (TECH FIG 3B).
It may be wise to exaggerate the cascade slightly so that as the graft relaxes and lengthens, the normal flexion cascade is created.
If the cascade is significantly exaggerated, however, a quadriga effect will result.
The proximal end of the tendon graft is then woven into the proximal recipient tendon stump with a Pulvertaft weave (TECH FIG 3C).
The recipient stump proximally can be either the FDS or the FDP to the injured finger. If the initial injury is more than a few months old, the muscle belly of the injured FDP or FDS may be atrophic or scarred proximally in the forearm, which would limit postoperative results. In this setting, the recipient tendon can be a side-to-side anastomosis to the neighboring FDP, which will provide the appropriate excursion.
All skin incisions are closed after ensuring hemostasis. The patient is then placed into a dorsal blocking splint with the wrist slightly flexed and the MP and IP joints flexed.
Rehabilitation is started within a few days (see Postoperative Care).
TENOLYSIS
This is often necessary after stage 2 of tendon reconstruction. Tenolysis is indicated when passive range of motion is greater than active range of motion. This surgery should not be performed until 3 to 6 months after stage 2.
The tendon must be exposed within zone II of the tendon sheath and tenolysis performed within the flexor sheath, taking care to preserve the A2 and A4 pulleys. If residual resistance is noted after tenolysis in the finger, an additional incision may be made at the level of the proximal junction to address any adhesions at that level.
Immediate hand therapy must be initiated postoperatively and can be easier on the patient if a wrist block is performed with a long-acting local anesthetic to preserve motor function while producing an effective sensory block.
ALTERNATIVE TO STAGE 1
The silicone rod that we use is considered “passive” and has no attachment to the proximal flexor motor.
An “active” alternative exists in which the rod can be secured to the tendon proximally and function as a graft. This can eliminate the need for stage 2 (TECH FIG 4).
These implants have been associated with a higher rate of complication in the limited number of studies that have examined them.
TECH FIG 4 • In an active tendon rod, the motor tendon is looped through the ring in the proximal rod, woven through itself, and fixed with nonabsorbable suture so that active motion can be performed.
PEARLS AND PITFALLS
POSTOPERATIVE CARE
The pre- and postoperative hand therapy is perhaps the most important component of this reconstruction procedure.
Patients must be motivated and compliant.
Therapists must be knowledgeable.
Before stage 1 and stage 2, the patient must have nearly full passive range of motion and a soft tissue envelope that will accommodate the subsequent stages of the process.
Stage 1 postoperative therapy is initiated within 48 hours and continues until the patient is ready for stage 2.
If pulley reconstruction was performed, the therapist can make ring splints for the patient to wear to protect the pulleys.
In general, the patient needs to be monitored for signs of infection. Edema should be controlled with elevation and compressive dressings as needed.
A custom splint is used when not exercising. This splint should hold the injured fingers in an intrinsic plus posture, with the MP joints in 70 degrees of flexion and the IP joints held in full extension. The wrist is held at neutral.
Passive range of motion of all involved digits is initiated, with emphasis on obtaining full composite flexion and full PIP extension.
Active range of motion exercises are also used to establish full active extension of all digits and full flexion of the uninvolved digits. Buddy-taping can be employed to facilitate motion of the operated digit.
The protocol for postoperative therapy after stage 2 is as follows:
0 to 3 weeks postoperatively
Precautions: No active finger flexion, no passive finger extension
The patient is splinted with a dorsal extension block splint holding the involved digits in an intrinsic plus posture and the wrist at neutral. The splint should be worn at all times.
Therapist-directed exercises begin with passive flexion and active extension in the splint. The PIP and DIP joints are secured to the splint in extension between exercise sessions.
Wound care and edema control are also incorporated and the patient must be observed for signs of infection.
3 to 6 weeks postoperatively
Precautions: Monitor closely for PIP flexion contractures, no passive finger extension, no splint removal
Active range of motion is initiated with “place and hold” exercises and progressed to full active range-of-motion exercises by 4 weeks after surgery while still in the splint.
Once the surgical wounds have healed, soft tissue massage should be incorporated to soften the volar tissues.
6 to 9 weeks postoperatively
Precautions: No resisted active motion, light functional activities only
Reliable patients can be weaned from the dorsal blocking splint.
The active flexion and extension exercises should be continued. Blocking exercises are initiated for PIP and DIP flexion to facilitate tendon glide and pull-through. Combined finger extension exercises are slowly initiated with the wrist in slight flexion. If the patient is a heavy scar former, this begins at 6 weeks; if average, at 7 weeks; if light, at 8 weeks.
9 to 12 weeks postoperatively
Precautions: No lifting or uncontrolled use
Splinting should be modified to correct any residual joint contractures and increase soft tissue excursion.
The patient can be allowed to begin progressive strengthening and should continue active range-of-motion and tendon gliding exercises as well as scar management as needed.
12 to 14 weeks postoperatively
Precautions: No heavy lifting
Splinting is continued as needed to address contractures.
Active range-of-motion and strengthening activities are continued. Resistance is gradually increased up to about 30 lbs by week 14.
14 to 16 weeks postoperatively
The patient progresses to full resistive strengthening exercises and activities.
A work-hardening program is initiated if needed to prepare for return to work.
If the patient is less reliable, the above protocol is followed except that dorsal blocking splinting is continued for up to 9 weeks and active motion is delayed until at least 4 weeks.
OUTCOMES
Because there are few alternatives to this staged process of reconstruction, there are limited articles comparing this treatment to another. Most of the investigations in the literature are retrospective reviews documenting overall postoperative motion and outcome ratings based on objective and subjective rating systems.
The larger studies have shown good and excellent results in the 70% to 80% range, depending on the grading system used.3–5
Final total active motion is about 70% of the contralateral uninjured digit.
Typically a significant discrepancy exists between ultimate total passive motion and total active motion. A flexion contracture of about 20 degrees at the DIP joint is common.3
The most common reported complication, seen in 30% of patients, was the need for a tenolysis.2–6
Other common complications that resulted in the need for further surgery included infection, tendon rupture, pulley rupture with bowstringing, and incorrect tendon tensioning.2–6
COMPLICATIONS
The most common complication is the development of adhesions that limit active motion. This can be assessed by a discrepancy between the active and passive range of motion. If there are significant discrepancies after at least 3 months of therapy after stage 2, then a tenolysis is recommended. This is followed immediately by a rigorous course of therapy to regain active motion. By 3 months, the tendon graft and junction sites should be strong enough to allow for unrestricted active motion.
Bowstringing is common if the A2 and A4 pulleys are compromised by initial trauma or released with the scar and adhesions during stage 1. In this setting, these pulleys should be reconstructed during stage 1. If they are found to be incompetent during the stage 2, then pulley reconstruction must be performed and the tendon graft must be delayed until the patient has healed from the pulley reconstruction and once again demonstrated nearly full passive range of motion.
Infection should be monitored for closely, given the previous history of a penetrating wound that caused the tendon laceration in the first place and the implantation of a synthetic material during stage 1 of the procedure. Infections should be managed aggressively because the local inflammation can produce further contractures and adhesions.
REFERENCES
1. Amadio PC, Hunter JM, Jaeger SH, et al. The effect of vincular injury on the results of flexor tendon surgery in zone 2. J Hand Surg Am 1985;10A:626–632.
2. Beris AE, Darlis NA, Korompilias AV, et al. Two-stage flexor tendon reconstruction in zone II using a silicone rod and a pedicled intrasynovial graft. J Hand Surg Am 2003;28A:652–660.
3. Frakking TG, Depuydt KP, Kon M, et al. Retrospective outcome analysis of staged flexor tendon reconstruction. J Hand Surg Br 2000; 25B:168–174.
4. Hunter JM, Singer DI, Jaeger SH, et al. Active tendon implants in flexor tendon reconstruction. J Hand Surg Am 1988;13A:849–859.
5. Hunter JM. Staged flexor tendon reconstruction. J Hand Surg Am 1983;8A:789–793.
6. Trumble TE, Sailer SM. Flexor tendon injuries. In: Trumble TE, ed. Principles of Hand Surgery and Therapy. Philadelphia: WB Saunders, 2000:231–262.