Application of Hand Therapy Extensor Tendon Protocol to Toe Extensor Tendon Rehabilitation

Discussion

The North Florida/South Georgia Veterans Health System is fortunate to have 4 CHTs on staff. CHTs take a 200 question 4 hour certifying exam after being licensed for a minimum of 3 years as a physical or occupational therapist and completing 4,000 hours of direct upper extremity patient experience. Pass rates from 2008 to 2018 ranged from 52% to 68%.³ These clinicians are key to the success of our hand surgery service, utilizing their education and skills on our elective and trauma cases. The hand therapy service applied their knowledge of hand extensor rehabilitation protocols to rehabilitate the patient’s toe extensor in the absence of clear guidelines.

Hand extensor tendon rehabilitation protocols are based on the location of the repair on the hand or forearm. Nine extensor zones are named, distal to proximal, from the distal interphalangeal joints to the proximal forearm (Figure 3). In his review of extensor hallucis longus (EHL) repairs, Al-Qattan described 6 foot-extensor tendon zones, distal to proximal, from the first toe at the insertion of the big toe extensor to the distal leg proximal to the extensor retinaculum (Figure 4).⁴ Zone 3 is over the metatarsophalangeal joint; zone 5 is under the extensor retinaculum. The extensor tendon repairs described in this report were in dorsal foot zone 4 (proximal to the metatarsophalangeal joint and over the metatarsals), which would be most comparable to hand extensor zone 6 (proximal to the metacarpal phalangeal joint and over the metacarpals).

The EDL originates on the lateral condyle of the tibia and anterior surface of the fibula and the interosseous membrane, passes under the extensor retinaculum, and divides into 4 separate tendons. The 4 tendons split into 3 slips; the central one inserts on the middle phalanx, and the lateral ones insert onto the distal phalanx of the 4 lateral toes, which allows for toe extension.⁵ The EDL common origin for the muscle belly that serves 4 tendon slips has clinical significance because rehabilitation for one digit will affect the others. Knowledge of the anatomical structures guides the clinical decision making whether it is in the hand or foot. The EDL works synergistically with the extensor digitorum brevis (EDBr) to dorsiflex (extend) the toe phalanges. The EDB originates at the supralateral surface of the calcaneus, lateral talocalcaneal ligament and cruciate crural ligament and inserts at the lateral side of the EDL of second, third, and fourth toes at the level of the metatarsophalangeal joint.⁶

Repair of lacerated extensor tendons in the foot is the recommended treatment. Chronic extensor lag of the phalanges can result in a claw toe deformity, difficulty controlling the toes when putting on shoes or socks, and catching of the toe on fabric or insoles.⁷ The extensor tendons are close to the deep and superficial peroneal nerves and to the dorsalis pedis artery, none of which were involved in this case report.

There are case reports and series of EHL repairs that all involves at least 3 weeks of immobilization.^4,8,9 The EHL dorsiflexes the big toe. Al-Qattan’s series involved placing K wires across the interphalangeal joint of the big toe and across the metatarsophalangeal joint, which were removed at 6 weeks, in addition to 3.0 polypropylene tendon mattress sutures. All patients in this series healed without tendon rupture or infection. Our PubMed search did not reveal any specific protocol for the EDL or EDB tendons, which are anatomically most comparable to the extensor digitorum communis (EDC) tendons in the hand. The EDC originates at the lateral epicondyle of the humerus, also divides into 4 separate tendons and is responsible for extending the 4 ulnar sided fingers at the metacarpophalangeal joint.¹⁰

Tendon repair protocols are a balance between preventing tendon rupture by too aggressive therapy and with preventing tendon adhesions from prolonged immobilization. Orthotic fabrication plays a key early role with blocking possible forces creating unacceptable strain or tension across the surgical repair site. Traditionally, extensor tendon repairs in the hand were immobilized for at least 3 weeks to prevent rupture. This is still the preferred protocol for the patient unwilling or unable to follow instructions. The downside to this method is extension lags, extrinsic tightness, and adhesions that prevent flexion, which can require prolonged therapy or tenolysis surgery to correct.^11-13

Early passive motion (EPM) was promoted in the 1980s when studies found better functional outcomes and fewer adhesions. This involved either a dynamic extension splint that relied on elastic bands (Louisville protocol) to keep tension off the repair or the Duran protocol that relied on a static splint and the patient doing the passive exercises with his other uninjured hand. Critics of the EPM protocol point to the costs of the splints and demands of postoperative hand therapy.¹¹

Early active motion (EAM) is the most recent development in hand tendon rehabilitation and starts within days of surgery. Studies have found an earlier regain of total active motion in patients who are mobilized earlier.¹² EAM protocols can be divided into controlled active motion (CAM) and relative motion extension splinting (RMES). CAM splints are forearm based and cross more joints. Relative motion splinting is the least restrictive, which makes it less likely that the patient will remove it. Patient friendly splints are ideal because tendon ruptures are often secondary to nonadherence.¹³ The yoke splint is an example of a RMES, which places the repaired digit in slightly greater extension at the metacarpal phalangeal joint than the other digits (Figure 5), allowing use of the uninjured digits.

The toe extensors do not have the juncturae tendinum connecting the individual EDL tendons to each other, as found between the EDC tendons in the hand. These connective bands can mask a single extensor tendon laceration in the hand when the patient is still able to extend the digit to neutral in the event of a more proximal dorsal hand laceration. A case can be made for closing the skin only in lesser toe extensor injuries in poor surgical candidates because the extensor lag would not be appreciated functionally when wearing shoes. There would be less functional impact when letting a toe extensor go untreated compared with that of a hand extensor. Routine activities such as typing or getting the fingers into a tight pocket could be challenging if hand extensors were untreated. The rehabilitation for toe extensors is more inconvenient when a patient is nonweight bearing, compared with wearing a hand yoke splint.