Extensor Tendon Lacerations to the Foot

A young man is brought into an emergency department after an electric lawn edger cut through his work boot and into the dorsum of his right foot. He has a clearly contaminated 5 cm x 1 cm laceration on the lateral side, and an underlying tendon is exposed. Sensation is diminished around the wound and he is unable to actively extend his 5th toe past a neutral position. How would you diagnose and repair his extensor tendon injury?

Evaluate Systematically: Every Foot, Every Time

Requirements to wear protective footwear in the workplace have decreased the incidence of occupational injury. Most work-specific footwear, however, leaves the dorsum of the foot vulnerable to blunt, penetrating, and cutting injuries.^1,2 A missed closed injury with tendon damage can lead to permanent disability and deformity.^1,3,4 This is why it’s crucial that ED providers consider the possibility of damage to the tendon, even in the absence of a deep laceration or visible damage to the footwear.

Anatomy

There are 2 sets of superficial tendons on the dorsum of the foot. The tendons of the extensor digitorum longus (EDL) and extensor hallucis longus (EHL) muscles are most superficial. Deep to these are the tendons of the extensor digitorum brevis (EDB) and extensor hallucis brevis (EHB) (Figure 1). The origin, insertion, and functions of each are reviewed in Table 1.⁵

Figure 1. Extensor tendons of the dorsal foot. EDL and EHL are seen in blue. EDB and EHB are seen in green. (Photo by James Powell)

Table 1. Summary of the origin, insertion, and function of the muscles of the dorsal foot

Key Points from the Physical Exam

Range of Motion Matters!

Because it is easy to get distracted by a deep and gory laceration, have a systematic approach to evaluating the motor function of the foot. Be sure to test:

• Extension and flexion of each digit
• The ability to hyper-extend a digit at the metatarsophalangeal joint
• Dorsiflexion of the ankle

Compare these findings to the unaffected foot. The inability to dorsiflex the ankle may represent a drop-foot deformity. Remember that toes are not as dexterous as fingers, and so a lack of hyperextension may be normal.  

2 Things to Palpate

Inspect and palpate all the tendons of the foot. Tendons should be palpable – a non-palpable tendon may be represent a transection! In this case, look for a painless mass proximal to the injury.³ Be sure to palpate distal pulses. If you cannot palpate a pulse, your next step is to evaluate with a Doppler.

Managing an Extensor Tendon Laceration of the Foot

Field Preparation

Obtaining a bloodless field will help with identifying a tendon laceration and any neurovascular damage. If hemostasis cannot be be achieved by the use of lidocaine plus epinephrine and initial direct pressure alone, a tourniquet-based approach can be taken:

1. Apply cast padding around the ankle.
2. Loosely wrap a pneumatic tourniquet (e.g. sphygmomanometer) over the cast padding.
3. Elevate the limb for at least 1 minute to assist with venous drainage.
4. Inflate the cuff until the pressure reaches > 260 mmHg. Clamping the cuff tubes with a hemostat may help to prevent a pressure leak.
5. Wrap the cuff with adhesive or padding to prevent cuff unraveling.

Tourniquet pressure is typically tolerated for around 20 minutes. Sedation can be used to ensure comfort if more time is needed.⁶ The maximum length of tourniquet time before an increase in the risk of complications is approximately 1 to 4 hours. Transient nerve palsies are associated with pressure at the tourniquet site, rather than the duration of use.^7,8 To improve exposure, you can consider extending the incisions at the border of the injury, perpendicular to the long-axis of the wound. This turns the laceration line into a ‘Z’ shape, and then the edges can be sutured open. (Figure 2). 

Figure 2. Extension of a laceration using 2 incisions made perpendicular to the long-axis of the wound, and held in place with sutures or skin hooks.

LacerationRepair.com provides an excellent video of the above technique:

Careful Inspection of the Wound

Inspection includes evaluation for:

• Tendon injury (while moving the digits into flexion and extension)1
• Foreign bodies
• Any surrounding nerve or vessel injury

A plain radiograph can be helpful in identifying any fragments of glass within the wound. The sensitivity for radiopaque foreign bodies is almost 98%.¹ It is important to identify nearby nerves before repairing a lacerated tendon. Accidental trauma or transection of a nerve can result in distal sensory loss and potentially a painful neuroma.

Extensor Tendon Repair

Extensor tendon lacerations often will require suture repair (Table 2).

Table 2. Indications for Suture Repair of an Extensor Tendon Laceration

*Consider patient factors: e.g. follow up, compliance, functional goals.

If a repair is performed, an approach similar to one used for repairing an extensor tendon on the hand (zone VI) can be applied successfully.^4,6 An ideal repair would use a braided, non-absorbable suture, (3-0 or 4-0), using a technique that buries the knot, such as a figure-of-eight pattern. A previous ALiEM post reviewed how to repair extensor tendon injuries of the hand and there is some overlap in technique.

Wound Surface Repair

Regardless of whether the extensor tendon is repaired, the wound surface should be repaired. For patients who are are referred to an orthopedist or podiatrist for delayed primary tendon repair, only re-approximate the epidermal layer of the wound.  For patients whose tendons are repaired in the ED, be aware that there is a fine sheath of paratenon around the tendon. This can be treated as a part of the surrounding connective tissue in terms of a layered closure.⁹ Because the extensor tendons of the foot lack a synovial sheath, deep sutures that close the connective tissue over the tendon, followed by superficial skin closure will be sufficient to prevent adhesions.⁶ Good results have been demonstrated in the repair of each of the extensor tendons of the foot.⁴

Splinting

All patients with suspected or confirmed extensor tendon lacerations should be splinted in a short leg posterior splint in 90 degree (toes in neutral position) for 3-4 weeks to prevent further damage.^3,6 Some physicians, however, prefer splinting with the toes in slight extension so that there is less theoretical stress on the extensor tendon.⁴ Others recommend continuous dynamic splinting, or a combination of static splinting followed by dynamic splinting for 6 to 8 weeks, offering earlier range of motion and weight bearing while still restricting stress on the affected tendon.¹⁰

Disposition

Repaired tendon injury or non-repaired partial (<50%) tendon injury: The patient should not weight-bear on the splinted leg and follow up with an orthopedic surgeon or podiatrist, depending your hospital’s resources.⁶ Typically this will be in 3-7 days.

Suspected tendon injury but are unable to locate it: The patient should not weight-bear on the splinted leg and urgent follow up with an orthopedic surgeon or podiatrist in 1-3 days.⁶ In most cases, tendon repair delayed up to 10 days will result in similar outcomes as primary closure on initial evaluation.

Back to the Case

After irrigation and exposure, a partial 10% extensor tendon laceration was discovered on the lateral side of the EDL tendon of the 5th digit, proximal to its insertion (Figure 3). Because the patient admitted he would not adhere to a plan for non-weight bearing, we felt that the extra strength of a suture may help to prevent further transection. The tendon was repaired with a 3-0 braided non-absorbable figure-of-8 suture. The connective tissue was closed around the tendon with 4-0 absorbable deep sutures, and the epidermis was closed using 4-0 non-absorbable horizontal mattress sutures (Figure 4). The patient was given crutches and asked to be non-weight bearing as much as possible until follow up in 7-10 days for suture removal and reassessment.

Figure 3. Patient’s right dorsolateral foot, showing the exposed EDL tendon of the 5th digit and a partial (10%) injury at the tip of the forceps (Photo by James Powell – used with patient permission)

Figure 4. Patient’s right dorsolateral foot showing the closed wound. Notice the ‘Z’ shape due to extension of the apices for exposure. (Photo by James Powell – used with patient permission)

Take Home Points

1. Extensor tendon injuries of the dorsal foot are common in the setting of dorsal foot penetrating trauma.
2. Many extensor tendon injuries, including those of the extensor digitorum longus and extensor digitorum brevis, can be effectively repaired in the emergency department.
3. Extensor tendon lacerations greater than 50% of its cross sectional area should be repaired.
4. Primary closure of extensor tendon lacerations can occur within 72 hours. Therefore, if proper assessment cannot be performed, clean and close the wound and arrange follow-up within 72 hours for delayed primary repair.
5. The suture size and technique are identical to repairing a Zone VI injury of the extensor tendons on the hand. Use a 3-0 non-absorbable braided suture, using a figure-of-eight technique.
6. The patient should be non-weight bearing on the affected foot. The foot should be splinted in a posterior leg splint with a neutral to extended position of the toes.

Author information

James Powell, MD

FRCP Emergency Medicine Resident
University of British Columbia

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