REHABILITATION OF EXTENSOR TENDON INJURIES

JEFFREY S. BRAULT, DO, PT

Hand specialists commonly see extensor tendon injuries. These injuries pose a difficult rehabilitation challenge. In the past, postoperative repair was followed by prolonged immobilization before motion was initiated. In the last decade there has been a shift in rehabilitation strategies to begin motion early in the postoperative period. This article reviews rehabilitation strategies for commonly seen extensor tendon injuries. Copyright �9 2000 by W.B. Saunders Company

KEY WORDS: tendon injuries, hand injuries, rehabilitation

Injuries to the extensor tendons are more common than flexor tendon injuries: Because of their superficial position, they are prone to laceration, abrasion, crushing, burns, and bites3 These injuries can be difficult to manage, and many complications such as extensor tendon lag, joint stiffness, and poor tendon excursion can result if initial treatment and postoperative rehabilitation is suboptimal. 2,3

Extensor tendon injuries are categorized into anatomical regions. This system defines 7 zones overlying the dorsal hand and wrist# Roman numerals are used to identify the zones: Odd numbers overlie the respective joints, and even numbers represent areas of the intermediate tendon re- gions (Fig 1). Injuries of the differing zones require differ- ent surgical repair and appropriate rehabilitative mea- sures.

Traditionally, extensor tendon injuries were either treated nonoperatively or surgically repaired and placed in continu- ous immobilization for 4 to 6 weeks. Achieving full range of motion was difficult because of tendon adhesion and joint contractures after prolonged immobilization. Over the last decade there has been a shift in the rehabilitation of proximal extensor tendon injuries (zones III through VII). The concepts of passive short arch motion and immediate active tension have been described by many as beneficial to extensor tendon healing and recovery. 5-8 Early motion and active tension of the repaired tendons assist in maintaining the integrity of the surrounding soft tissue, controlling edema, reducing tendon adhesions, preventing contrac- tures, and promoting tendon repair. 9,1~ The intent of this early "rehabilitation of a healing tendon is simply reestab- lishing its ability to glide and transmit forces without creating gapping or rupture of the repair site. 'ql

The purpose of this article is to review rehabilitative interventions for the most commonly encountered zone

From the Mayo Clinic, Rochester, MN. Address reprint requests to Jeffrey S. Brault, DO, PT, Mayo Clinic,

PM&R Department, E-10, 200 First St, SW, Rochester, MN 55905. Copyright �9 2000 by W.B. Saunders Company 1071-0949/00/0701-0006510.00/0 doi:10,1053/oa.2000.5801

injuries. This information will provide the hand surgeon with an understanding of the various types of splints and rehabilitation procedures used for treatment of extensor tendon injuries.

ZONE I

Injury to the most distal aspect of the extensor tendon overlaying the distal interphalangeal (DIP) joint usually results in a flexion deformity of the DIP joint. These injuries, commonly referred to as mallet, baseball, or dropped finger, are the result of forced flexion of an extended DIP joint. Bony avulsion of the distal tendon insertion may occur. If this deformity goes untreated, it may result in an imbalance collapse of the finger (hyperextension of the proximal interphalangeal [PIP] joint and flexion of the DIP joint), or swan neck deformity. 12

In closed zone I injury with mallet deformity, splint therapy is widely used over primary repair. 11,12 Conserva- tive treatment of acute injuries, lasting less than 3 weeks, consists of continuous immobilization of the DIP joint in slight hyperextension (0 ~ to 15~ Many types of DIP splints are available, but the most widely used is the Stack polyethylene splint 12 (Fig 2). Extension greater than 15 ~ of the DIP should be avoided to alleviate the potential for skin or tendon ischemia and potential necrosis. The exten- sion splint should be worn continuously for 6 weeks and may be removed once a day to allow skin aeration and to prevent maceration. During splint removal the DIP joint must be held in extension. If flexion of the DIP joint is allowed, immobilization should be reimplimented for an additional 6 weeks, n During this immobilization period active and passive range of motion exercises should be initiated at the metacarpal phalangeal (MCP) and PIP joints (Fig 3). Re-evaluation should be performed weekly to ensure proper splint size and to monitor skin integrity. After 6 weeks, active DIP range of motion exercises should be performed hourly. At 7 weeks, if no extensor lag is identified, passive pain-free DIP range of motion can be initiated. Patients should continue to wear the splint

Operative Techniques in Plastic and Reconstructive Surge04, Vol 7, No 1 (February), 2000: pp 25-30 2 5

Fig 3. Motion exercises of the MCP and PIP joints.

Fig 1. Zones of extensor tendons.

between exercise sessions and at night. At 8 weeks, if no extensor tendon lag is noted, the splint use may gradually be discontinued.

In chronic DIP tendon injuries (ie, lasting longer than 3 weeks), immobilization in DIP extension should be main- tained for 8 weeksJ 2 Active range of motion exercises of the MCP and PIP joints should be performed. After 8 weeks DIP active range of motion exercises should be done hourly. At 9 weeks, if extensor lag is less than 10 ~ hourly passive, pain-free DIP range of motion can be initiated. Patients should continue to wear the splint between

Fig 2. Stack splint immobilizes the DIP joint in slight exten- sion,

exercise sessions and at night. The splint use is discontin- ued at 10 weeks if extensor lag is not present (Table 1).

ZONE II

Zone II injuries involve the terminal extensor tendon in the region of the middle phalanx. Distal to this region, the lateral bands fuse to form the terminal extensor tendon} 3 Zone II injuries are most often the results of laceration. In this region pr imary tendon repair is recommended; how- ever, pinning and splint therapy have also been de- scribed. 12 Conservative and postoperative splint therapy protocols are the same as for zone I injuries (Table 1).

ZONE I I I

In zone III the central tendon is the pr imary extender of the PIP joint} 3 Injury in this region can be the result of direct forceful flexion of an extended PIP joint, laceration, abra- sion, or bite. If untreated, the lateral bands slip volarly, resulting in a boutonni6re deformity. 12

Acute open injuries are usually repaired by pr imary central tendon repair. Acute closed injury treatment is controversial, but most surgeons recommend conservative immobilization for 6 weeks. 15,16 In chronic nonfixed defor- mity, splinting is recommended, and for fixed deformity, reconstructive surgery is the treatment of choice. 12 Evans 14 has delineated a therapy program in which early motion and tension are introduced 24 to 48 hours after pr imary repair. Except for hourly exercise, the DIP and PIP joints should be splint immobilized in 0 ~ of flexion (Fig 4). Two exercise splints are fabricated for each patient. The first, a volar static splint, allows 30 ~ of PIP joint flexion and 20 ~ to 25 ~ of DIP joint flexion (Figs 5 and 6). During exercise the wrist is maintained in approximately 30 ~ of flexion and the MCP joints in a neutral position. The second volar splint maintains the PIP joint in 0 ~ of extension and allows for free DIP joint flexion unless the lateral bands are repaired;

2 6 JEFFREY S. BRAULT

TABLE 1. Zone I and Zone II Injuries

Acute DIP injuries (Mallet Deformities Lasting < 3 Wk) Weeks Splint Exercises

0-5 Continuous DIP extension (Stack splint) (Fig 2) Active flexion and extension of PIP and MCP (hourly)

6 Worn between exercises and at night Active flexion and extension of DIP (hourly) 7 Worn between exercises and at night Passive flexion and extension of DIP (hourly) 8 If no extensor lag, may gradually discontinue Continue with active and passive DIP exercises

splint

Chronic DIP Injuries (Mallet Deformities Lasting >3 Wk) Weeks Splint Exercises

0-7 Continuous DIP extension (Stack splint) (see Active flexion and extension of PIP and MCP Fig 2) (hourly)

8 Worn between exercises and at night Active flexion and extension of DIP (hourly) 9 Worn between exercises and at night Passive flexion and extension of DIP (hourly)

10 If no extensor lag, may gradually discontinue Continue with active and passive DIP exercises splint

Wound and Skin Care

Remove splint daily to check for skin integrity/ hygiene (maintain DIP in extension)

Wound and Skin Care

Remove splint daily to check for skin integrity/ hygiene (maintain DIP in extension)

1 Abbreviations: DIP, distal interphalangeal joint; MCP, metacarpophalangeal joint; PIP, proximal interphalangeal joint. Data from Evans 11 and Minamikawa. t2

then flexion is limited between 0 ~ to 30 ~ (Figs 7 and 8). Patients are followed up weekly by a skilled therapist to ensure that no extensor lag develops. If extensor lag is not noted at 2 weeks, the first exercise splint can be modified to allow 40 ~ of flexion. This can be increased to 50 ~ at the fourth postoperative week, and full flexion is allowed at 6 weeks. The exercise splints should not be advanced if extensor lag is identified (Table 2).

ZONE IV

In zone IV, the extensor digi torum tendons run dorsal to the proximal phalanx. The tendons of the intrinsic hand muscles are located laterally. 13 In this region partial tendon injuries usually spare the lateral bands, x2 Because of the intricate relationship between the tendon and bone in this zone, injury can often result in considerable adhesions and loss of motion. If no extensor lag is noted at the PIP joint, repair of the tendon is rarely required. 2 If lag is present, primary repair is recommended. 12 Rehabilitation and splint-

ing have been described and are similar to those applied to zone III injuries 11,12 (Table 2).

ZONE V

Zone V, located over the MCP joints, is the most common area for extensor tendon injury. 12 In this region the tendon is susceptible to laceration, bite, or joint dislocation. If the tendon disruption is the result of a h u m a n bite (fist to the mouth), the injury should be copiously irrigated, the w o u n d left open, and the patient started on broad- spectrum antibiotics. 12 Acute open injuries (nonhuman bites) and closed injuries are usually repaired} 4-15 Many authors have recommended that passive splinting be initiated within the first postoperative week, preferably before 48 hours. 6,8,12,14 This is achieved by a forearm-based dorsal dynamic extension splint (Fig 9). This splint places the wrist at 40 ~ of extension and allows 30 ~ to 40 ~ of active MCP joint flexion, but only passive extension (Fig 10). The amount of active flexion can be limited by stop beads on the suspension line or by use of a volar block. This degree

Fig 4. Immobilization splint of PIP and DIP joint, Fig 5. Exercise splint #1; finger in neutral position.

REHABILITATION OF EXTENSOR TENDON INJURIES 2 7

Fig 6. Active range of motion exercises allowing for 30 ~ of PIP and 20 ~ to 25 ~ of DIP flexion,

of motion results in 5 mm of tendon excursion in zone V. 2 The amount of active flexion range can be increased to 50 ~ to 60 ~ by the fourth week. The patient is instructed to perform hourly exercises. A static night splint or MCP block splint holds the wrist in 30 ~ to 40 ~ of extension and the MCP joints at 0~ this is used throughout rehabilitation (Fig 11). In addition to early passive motion, immediate active exercises have been advocated. 8,14 These exercises are initiated by a skilled therapist who positions the wrist in 20 ~ of flexion and passively positions the MCP joint in 30 ~ of flexion. While maintaining the interphalangeal joints in the neutral position, the patient actively extends the MCP joints back to the neutral position. The weight of the patient's fingers provide a safe amount of stress through the repair site, stimulating tendon healing. 17 At week 5 the dynamic splint is discontinued, and the MCP block splint is continued between exercise sessions and at night. At week 6 passive flexion exercises can be initiated and buddy taping used to enhance composite flexion of the digits. At week 7 progressive strengthening can be initiated. By week

Fig 8. Active flexion and extension of the DIP joint.

9, if no extensor lag develops, all bracing can be discontin- ued, and progressive active exercises can be incorporated into a home program (Table 3).

ZONE VI

This zone of the hand lies over the metacarpals. Here, the 4 individual extensor digitorum tendons and extensor propri- ous tendons of the small and index fingers transverse. Injuries to this region present a similar clinical picture as in zone V. If there are partial or single tendon injuries, weakness may be difficult to detect because of the attach- ments of the juncturae tendinum between adjacent exten- sor tendons, s The only physical sign may be slight extensor lag of one finger relative to its neighbor. Treatment of this region has conventionally been primary repair followed by 4 to 6 weeks of immobilization with finger and wrist extension. Use of dynamic splints shortly after repair has been demonstrated to be of similar benefit as protocols used for zone V injuries 8,14 (Table 3).

ZONE VII

Zone VII is at the level of the wrist. Tendons in this region run through a fibro-osseous tunnel covered by the extensor retinaculum. Complete laceration of the finger extensor tendons in this area is rare. 8 If injury does occur in this zone the tendons retract considerably. Primary repair requires greater exposure and increases the risk of adhesions. 12 Postoperative rehabilitation is similar to zone V rehabilita- tion protocols 8,14 (Table 3).

Fig 7. Exercise splint #2; PIP joint in neutral.

CONCLUSION

The rehabilitation of extensor tendon injuries has been modified greatly in the last 10 years. The concept of prolonged immobilization has been replaced by early mobilization in postoperative repair of injuries in zones III through VII. Early referral to a qualified hand therapist for initiation of proper splinting, edema and pain control, patient education, and initiation of an early motion pro-

28 JEFFREY S. BRAULT

TABLE 2. Zone III and IV Injuries (Immediate Motion)

Weeks Splint Exercises Wound and Skin Care

Start 24-48 h PIP and DIP neutral splint (Fig 4) --Dai ly removal of splint for wound cleaning 0-2 wk - -Edema control with compressive wrap

2-3 wk

4-5 wk

6 wk

If no extensor lag noted, discontinue use of splints

If no extensor lag noted, discontinue use of splints

If no extensor lag noted, discontinue use of splints

Exercise hourly with 2 splints: Splint I allows 30 ~ of PIP and 25 ~ of DIP

ROM (see Figs 5 and 6) Splint 2 PIP in neutral position, DIP flexion

(see Figs 7 and 8) Splint 1 increases PIP flexion to 40 ~ Splint 2 continues Splint 1 increases PIP flexion to 50 ~ Splint 2 continues Full active PIP and DIP flexion

Abbreviations: DIP, distal interphalangeal joint; PIP, proximal interphalangeal joint; ROM, range of motion. Data from Evans 11 and Minamikawa. 1-2

Fig 9. Forearm-based dorsal dynamic extension splint (low profile).

Fig 10. Splint allows for 30 ~ to 40 ~ of active MCP flexion with passive re- turn to the neutral posi- tion. Flexion is limited by stop beads on outrigger strings.

Fig 11. MOP block splint.

TABLE 3. Zone V, VI, and VII Injuries

Weeks Splint Exercises Wound and Skin Care

Start 24-48 h 0-3 wk

4 wk

5 wk

6 wk

7wk

9 wk

Dorsal dynamic extension splint (Fig 10) Exercise hourly in extension splint allowing Night splint: MCP block splint (see Fig 11) 300-40 ~ of MCP flexion

With skilled therapist--wrist at 20 ~ , passive MCP flexion to 30~ performs active extension (daily to 3x wk)

Continue with dynamic day splint, static night Increase active ROM to 50o--60 ~ splint

Discontinue dynamic extension splint MCP block splint worn at night and between

exercises MCP block splint

MCP block splint

If no extensor lag, discontinue all splints

Increase active ROM exercises to full motion

Passive flexion exercises of MCP and IP joints (buddy tape)

Progressive extension exercises, with mild resistance

Progress active and passive exercises

Daily removal of splint for wound cleaning Edema control with compressive wrap

Abbreviations: IP, interphalangeal; MCP, metacarpophatangeal; ROM, range of motion. Data from Evans 11 and Minamikawa. 12

g r a m is o p t i m a l . T h e s e e a r l y m o t i o n p r o g r a m s h a v e re-

s u l t e d in i m p r o v e m e n t o f r a n g e of m o t i o n , s h o r t e r t i m e to

r e c o v e r y , l o w e r e x p e n s e , a n d b e t t e r f u n c t i o n a l o u t c o m e . 14

REFERENCES

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3. Newport ML, Blair WF, Steyers CM: Long-term results of extensor tendon repair. J Hand Surg [Am] 15A:961-966, 1990

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5. Evans RB: Early short arc motion for the repaired central slip. J Hand Surg [Am] 19A:991-997, 1994

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7. Saldana MJ, Choban S, Westerbeek P: Results of acute zone III extensor tendon injuries treated with dynamic extension splinting. J Hand Surg [Am] 16A,1145-1150, 1991

8. Thomas D: Postoperative management of extensor tendon repairs in zones V, VI, VII. J Hand Ther 9:309-314, 1996

9. Amiel D, Woo SL, Harwood FL: The effect of immobilization on collagen turnover in connective tissue. A biochemical-biochemical correlation. Acta Orthop Scand 53, 325-332, 1982

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11. Evans R: An update on extensor tendon management, in Hunter JM, Mackin EJ, Callahan AD (eds): Rehabilitation of the Hand: Surgery and Therapy, vol I (ed 4). St Louis, MO, Mosby, 1995, pp 565-606

12. Minamikawa Y: Extensor repair and rehabilitation, in Peimer C (ed): Surgery of the Hand and Upper Extremity, vol 1. New York, NY, McGraw-Hill, 1996, pp 1163-1188

13. Rosenthal EA: The extensor tendon: Anatomy and management, in Hunter JM, Mackin EJ, Callahan AD (eds): Rehabilitation of the Hand: Surgery and Therapy, vol 1 (ed 4). St Louis, MO, Mosby, 1995, pp 519-564

14. Evans RB: Rehabilitation techniques for applying immediate active tension to the repaired extensor system. Techniques Hand Upper Extremity Surg 3:139-150, 1999

15. Tubiana R: Injuries to the digital extensors. Hand Clin 2:149-156, 1986 16. Wilson RL: Management of acute extensor tendon injuries, in Hunter

JM, Shneider LM, Mackin EJ (eds): Tendon Surgery in the Hand. St Louis, MO, Mosby, 1987, pp 284-294

17. Evans RB, Thompson DE: The application of stress to the healing tendon. J Hand Ther 6:262-298, 1993

3 0 JEFFREY S. BRAULT