TENDON DISORDERS IN THE HAND
Trigger Finger
Trigger finger is the result of localized
tenosynovitis of the superficial and deep flexor tendons in the region of the
fibrous sheath (annular ligament, or pulley) at a metacarpal head (A1). It
occurs most often in the long or ring fingers (occasionally in the thumb) of
middle-aged women,
but its exact cause has not been determined. Trigger finger may also be
associated with rheumatoid arthritis and diabetes involving several fingers.
The localized inflammation causes a thickening and
narrowing of the sheath, and a nodular or fusiform enlargement develops in the
tendons distal to the pulley. These changes interfere with and may actually prevent the smooth gliding of the tendons through the fibrous sheath.
Clinical Manifestations
In the early stage, the nodule produces a slightly painful
clicking or grating as it passes through the constricted sheath when the finger
is flexed and extended. As the pathologic changes in tendon and sheath advance,
flexion of the finger is arrested in the middle range; as more force is
required to pull the nodule through the constricted pulley, the finger snaps
painfully into full flexion or extension. Later, the tendon nodule may not pass
through the stricture, and the finger is partially fixed in extension or
flexion, usually the latter. Passive manipulation of the flexed finger may
force the nodule through the sheath, producing a painful snap into extension.
On examination, the patient can usually demonstrate
the trigger finger and may be able to demonstrate the finger locking in
flexion; flexion and extension produce crepitation. Palpation over the
metacarpal head reveals a tender nodule that moves with the tendon.
Treatment
Although trigger finger often subsides spontaneously,
a cortisone injection into the tendon sheath may alleviate the triggering in up
to 80% of patients. If painful triggering continues, a minor operation can provide permanent relief. A 34
-inch transverse incision is made just distal to the distal flexion crease over
the metacarpal head, exposing the flexor tendons and sheath. The constriction
is relieved by completely incising the thickened A1 pulley longitudinally along
its radial or ulnar aspect, taking care to avoid the digital nerves. The
patient can now actively flex and extend the finger freely and comfortably, and the pulley heals again but has a
larger diameter.
Flexor Tendon Repair
Flexor tendon injuries can occur by various mechanisms,
but the most common injury is a laceration. “Jersey finger” is an avulsion of
the flexor digitorum profundus tendon that occurs typically in the ring finger as a result of
a forced gripping versus resistance, as seen when the finger gets tied up in an
opponent’s jersey during a football tackle. Flexor tendon laceration often
occurs in the household on broken glass, from tin can lids, or inadvertently
with a kitchen knife. Laceration can occur anywhere along the length of the
finger, with the most complex occurring in zone 2 over the proximal phalanx
where the profundus and sublimis tendons travel together in a fibro-osseous
sheath. Typically, the hand is clenched and therefore the skin injury is more
proximal than the tendon injury, requiring careful attention to the physical
examination.
Primary repair in the first 6 weeks produces acceptable
functional results; after 6 weeks, tendon grafting or arthrodesis of the distal
interphalangeal joint is the treatment of choice. Repair of the lacerated or an
avulsion flexor digitorum profundus tendon to the distal phalanx is typically
performed by using a bone suture anchor placed in the distal phalanx or passage
of the locking suture weave placed in the tendon through the bone from palmar
to dorsal and tying the sutures over the dorsal cortex. Postoperatively, a
dorsal splinting protocol prevents maximal extension during the early phases of
healing with early passive motion and active flexion initiated by 3 weeks.
Strengthening is begun at the 6-week mark.
Tendon repair is most successful after a sharp laceration
of the tendons as opposed to tearing seen with saw injuries. The goal is to
obtain a strong repair with the least amount of bulk in the tendon so the
tendons will pass smoothly through the pulleys in the fibro-osseous sheath. The
flexor tendon repair consists of two layers of sutures. The first layer is a
core stitch most commonly performed to obtain four passes across the tendon
repair. This provides significant strength to allow early active range of
motion. The second layer is a circumferential epitendinous stitch with a fine
nonabsorbable suture to help reduce the volume and friction of the repair.
Owing to the site of laceration, at times a four-strand repair is not possible and separate two-strand core stitches are placed in each stump and then tied in order to work
around the pulleys. A second core stitch can then be placed in a horizontal
mattress fashion, providing a total of four core stitches.
Therapy after flexor tendon repair requires highly
skilled hand therapists to work closely with patients to reduce edema and guide
the patient through the different stages of recovery. The initial stage is typically passive
motion to initiate tendon gliding in a safe manner, followed by active range of
motion and later strengthening. Full recovery can take up to 6 months, and it
is not uncommon that a secondary operative procedure is required to perform a
tenolysis to break down the adhesions that occur after wound and tendon healing.
