TENDON LACERATIONS AND OTHER TENDON DISORDERS ABOUT THE ANKLE

The tendon lacerations discussed here involve the following tendons: flexor hallucis longus (FHL), flexor digitorum

longus (FDL), extensor digitorum longus (EDL), extensor hallucis longus
(EHL), anterior tibial (AT), and posterior tibial (PT) tendons.

The FHL muscle originates from the deep posterior
compartment of the leg. The FHL tendon passes beneath the sustenaculum
tali and continues distally, crossing deep to the FDL tendon at the
flexor knot of Henry. At this point the tendon produces a tendinous
slip that inserts into the FDL tendon (16). The
FHL tendon is covered by two synovial sheaths. The first provides
coverage from the ankle joint to a point just distal to the flexor knot
of Henry; the second provides coverage from the first metatarsal base
to the tendon insertion.

The EDL, EHL, and AT tendons originate from the anterior
compartment in the leg. Each muscle produces a tendon that is enclosed
in a synovial sheath and is retained in position by a thickened section
of crural fascia known as the extensor retinaculum. There are
individual sheaths for the anterior tibial tendon and extensor hallucis
longus tendon and a common sheath for the extensor digitorum longus
tendons (17).

The anatomic features of the posterior tibial tendon are described in the POSTERIOR TIBIAL TENDON DYSFUNCTION section of Chapter 118.

The subcutaneous positions of the tendons about the foot
and ankle predispose them to injury by direct trauma. Laceration of the
plantar or dorsal aspect of the foot may produce disruption of
tendinous, vascular, or neurologic structures.

Injuries associated with foot lacerations are commonly
missed. Establish the full extent of the injury by careful physical
examination, appropriate radiographic imaging, and, when necessary,
surgical exploration. When primary repair is indicated, techniques used
are similar to those for flexor tendon injuries in the hand.

Document the mechanism of injury. Determine the exact
anatomic area of injury. Check the vascular and neurologic status and
follow this by an analysis of tendon function. Remember that the FHL
tendon provides a tendinous slip to the FDL tendon. If the FHL tendon
is disrupted proximal to this slip, active flexion at the hallux
interphalangeal joint may be produced by the FDL tendon. Therefore, the
presence of active hallux interphalangeal joint plantarflexion does not
rule out FHL tendon injury.

All lacerations require plain radiographic imaging to rule out concomitant bony injury and the presence of foreign material.

Tendon lacerations can be classified on the basis of
mechanism of injury, degree of injury (incomplete versus complete),
location of injury (insertional versus noninsertional, relation to
synovial sheath, relation to retaining structures), and by the presence
of associated neurovascular or tendinous injury. With regard to
laceration of the FHL tendon, the integrity of the flexor hallucis
brevis is an important consideration.

In the emergency department, provide routine wound care
and give appropriate tetanus prophylaxis. Generally speaking, isolated
tendon laceration about the foot may be treated by nonsurgical or
surgical means. Repair primarily complete laceration of the Achilles,
PT, AT, peroneal, EHL, and FHL tendons when local conditions are
favorable. Functional (partial) lacerations as well as laceration of
the brevis tendons are typically not repaired. Do a meticulous
debridement and evaluation of associated structures and repair if
needed.

Placing sutures in a traumatic wound increases the risk
of infection. Therefore, perform primary tendon repair only if local
wound conditions are favorable. Digital nerve injury may be complicated
by neuroma formation or the onset of reflex sympathetic dystrophy.
Minimize the risk of posttraumatic neuroma formation by transplanting
the proximal end of the lacerated digital nerve into a local muscle
belly. If a painful neuroma occurs, treatment with desensitization
modalities is indicated. Occasionally, referral to a pain management
specialist is required.

When local conditions permit, we prefer primary tendon
repair, especially in the pediatric and athletic population. Because of
their propensity to form neuromas, we do not repair digital nerve
lacerations but transplant the proximal nerve to a well-protected
location.

Pain is present in the posterior ankle deep to the
Achilles tendon. Deep palpation in this area may cause tenderness. The
pain may be aggravated by passive motion of the great toe. With
significant swelling, the tendon may become entrapped and cause
triggering, leading to clawing of the great toe (2,7,8,10,12,15,19).
Entrapment can be verified by comparing great toe dorsiflexion with the
ankle in the plantarflexed position and when dorsiflexed. With
entrapment, dorsiflexion of the toe is limited with the ankle also
dorsiflexed but possible when the ankle is plantarflexed (9).

Routine radiographs will be unremarkable. The presence
of a large posterior process or os trigonum may cloud the diagnosis.
Magnetic resonance imaging (MRI) is a useful test for evaluating
questionable cases (11,19)
where fluid can be identified about the tendon in the fibro-osseous
tunnel and intrasubstance tears in the tendon may also be present.

Nonoperative treatment consists of activity limitation
and nonsteroidal antiinflammatory medications for 10 to 14 days.
Immobilization in a short-leg walking cast with extended toe plate to
prevent great toe motion may be helpful as well.

Treat athletes who do not obtain relief with
conservative methods or those who have persistent triggering of the
great toe with release of the fibro-osseous tunnel of the FHL. The
medial approach is favored because it allows access to the entire
fibro-osseous canal. Full return of function can be expected with this
procedure (2,8,10,12,14,19).

The anterior tibialis (AT) muscle originates from the
proximal tibia and interosseous membrane. It becomes tendinous at the
level of the distal tibial metaphysis. The anterior tibialis tendon
passes over the front of the ankle and runs with a straight course
under the superior extensor retinaculum to attach to the dorsum of the
medial cuneiform and base of the first metatarsal. It is the primary
dorsiflexor of the ankle and also helps invert the foot (3).
Despite its subcutaneous course, the tendon is rarely injured, probably
because it does not change direction against a bony fulcrum and because
of its excellent blood supply (5,20).

Tendinitis can occur from overuse, particularly from
hiking downhill, and has been described from direct pressure against
the tendon by ski boots (20). Rupture of the
anterior tibialis tendon is an unusual injury that occurs in two
distinct populations. The most common presentation is in the elderly,
who usually have an atraumatic rupture and typically note the insidious
onset of a foot drop (9,13). The second presentation is an acute traumatic rupture in older athletes, but it can also occur in young athletes (3,13,18).

Patients with tendinitis have tenderness over the course
of the tendon and pain on resisted dorsiflexion of the ankle. A rupture
can be diagnosed by a visual or palpable defect in the tendon, foot
drop, and weakness of ankle dorsiflexion (Fig. 94.1).

Plain radiographs are unremarkeable. The rupture can be easily identified with an MRI scan (11,13). This is essentially a clinical diagnosis, however, and an MRI is usually not necessary.

Treat tendinitis with activity limitation and
nonsteroidal medications. If pain is caused by direct pressure against
the tendon, remove the irritant.

Chronic rupture in the older patient may be satisfactorily treated with a brace or may even be left untreated (1).
The acute rupture is probably best treated with surgical
reconstruction. In cases in which it is recognized early, a direct
repair of the tendon is possible (9,13,18,20). If it has been unrecognized for several months, reconstruction

with either an EHL tendon transfer or interposition of an EDL tendon
graft may be used, allowing return to recreational activities (13).