The Initiation of Therapy: Timing

No studies have discussed specifically the optimal timing to initiate motion of the extensor tendons. Following flexor tendon repair, investigators have proposed initiating active flexion at postsurgical day 3 to 5, based on experimental evidence.⁷ Though it is unsure whether we can extrapolate the conclusions from the flexor tendon research to the extensors, we generally adopt these conclusions, because of a paucity of investigation on extensors in this regard.

Ideally, postoperative mobilization should be initiated when the therapist has a wide margin of safety between the tendon gapping strength and the load required to initiate tendon gliding.⁵ Active tendon gliding has to overcome resistance caused by (1) friction between tendons and their surrounding structures; (2) resistance resulting from joint stiffness, edema, and adherence to surrounding tissues; and (3) resistance of antagonist muscles.⁵ In zone 7, the tendon encounters additional resistance from the restrictive extensor retinaculum, that covers the tendons tightly.

When the patient is immobilized for the first 3 or 5 days after surgery, extra care must be taken to ensure correct positioning of the hand, which should be checked at the first or second day with assessment of pain, excessive swelling, or bleeding. An earlier dressing change may be necessary.

Patient Referral Information

Detailed and specific information about the patient, the injury, and operative procedures performed are helpful in deciding protocols for individual patients. A copy of the operative report is invaluable in this regard. The therapist needs to know the mechanism of injury, level and severity of the tendon injuries, and structures repaired. It is also important to know the type of tendon repair and the strength of the repair. The surgeon should inform the therapist if the tendon is frayed, if there is the possibility of a postoperative infection, or if tissues were seriously damaged. All these factors greatly influence the extent and amount of scar and the probability of tendon adherence or repair rupture. Associated injuries of bones, nerves, blood vessels, and skin should also be taken into account in deciding protocols that best suit the patient. Information on the use of skin grafts and the location of repaired blood vessels is of great importance since pressure over these areas should be avoided by careful design of a splint. Finally, therapists should obtain information regarding pertinent medical conditions that may influence wound healing or the normal progression of tendon healing.⁷

Record Keeping

Active and passive range of motion of the hand should be regularly measured and recorded. Improvement of range of motion is an indication for the effectiveness of therapy and helps to decide if a protocol needs modifications. Function is assessed by measuring passive and active range of motion of the joints. Extensor pollicis longus (EPL) function, after a transfer of the extensor indices to the EPL tendon, can be measured by the distance of thumb elevation from the surface of a table on which the hand is placed flat.⁸ In addition, the Kapandji thumb rule by giving a score (0-10 score; 0: to the metacarpophalangeal joint level of the index finger, and 10: to the distal palmar crease of the little finger) to how far the thumb can reach different parts of the fingers can be used to score thumb opposition.⁹

The timing of initiating or modifying therapy and frequency of exercises, such as active joint extension, should be clearly recorded. The strength of finger and wrist extension, pain, and potential signs and symptoms of complex regional pain syndrome should also be recorded.

Zones 1 and 2 (Mallet Finger)

Zones 1 and 2 extensor tendon injuries may involve avulsion fracture from the base of the distal phalanx or present as tendon disruption alone, leading to mallet finger deformity. A full-time splint is usually applied for 6 to 8 weeks with the DIP joint held in extension for both types of mallet finger.¹⁰ After the initial 6 to 8 week splinting period, the splint should still be worn at night and during strenuous activities for 2 to 6 weeks. Several types of splint are available: foam-padded aluminum splints, molded plastic splints, and thermoplastic splints. With splinting, most acute injuries achieve a success rate of around 80%.¹¹ Therapy after this splinting period is not always continued.^10,12 Patients returning to their daily activities directly after splint removal may risk a tendon re-rupture or develop a DIP joint extension lag. The entire course of therapy can be divided into the following phases:

First Phase (6 to 8 Weeks): Therapy During Splinting Phase

After a mallet finger injury, a splint is applied to hold the distal interphalangeal (DIP) joint in extension.¹³ It is preferable to apply a custom made splint to position the DIP joint in submaximal extension, that is, maximum extension that does not produce skin blanching. However, circulation is more often compromised by too much pressure of the splint rather than too much DIP joint hyperextension.

The splint should not include the proximal interphalangeal (PIP) joint and should allow full PIP joint flexion. Nonelastic adhesive tape should securely fix the splint to the volar skin of the middle part of the finger. In the supple and hypermobile fingers, a mallet finger injury encourages development of a swan neck deformity. This can be prevented by adding a 30° extension block for the PIP joint as part of the splint (Figure 40-2).

Figure 40-2 A mallet finger splint often used by these authors to immobilize the DIP joint and prevent PIP joint hyperextension with a PIP joint extension block.

When the patient is less compliant or needs more secure protection, a plaster of Paris or Quickcast cylindrical cast is a good choice to immobilize the DIP joint. Therapists often have difficulty keeping the DIP joint extended while fabricating a plaster cast. This difficulty may be overcome if an adhesive nonelastic tape is first applied starting on the volar aspect of the distal end of the finger and ending on the dorsum, crossing the DIP joint crease and extending to the middle phalanx. This tape holds the DIP joint in extension and the plaster of Paris is easily applied over it. The tape also prevents the plaster from slipping off as the plaster adheres to the tape.

With the splint/cast in place, the patient is instructed to perform active PIP flexion exercises with the adjacent fingers held in extension. With this exercise, the flexor digitorum profundus (FDP) cannot be activated and the flexor digitorum superficialis (FDS) will flex the PIP joint only, eliminating flexion forces at the DIP joint.

The patient is instructed not to carry heavy objects with the injured hand and to avoid playing contact sports, etc. We prefer not to have the patient remove the splint but have the therapist remove the splint carefully every week. If the skin has signs of pressure or maceration, the splint needs to be adjusted or an alternative splint design considered.

Second Phase (6/8 to 10 Weeks): Initial Exercises Without Splint

Only when there is no extension lag at the DIP joint can the patient be allowed to start actively flexing the DIP joint and gently increasing the flexion force. The active exercises are done 3 to 5 times a day out of the splint. The amount of DIP joint flexion can be controlled by using a large diameter cylinder (Figure 40-3). With the hand on top of the cylinder rolling it forward allows some DIP joint flexion and rolling it backward provides a passive assistance for DIP joint extension. The patient then lifts the hand and holds this position for 5 seconds, similar to place-hold active exercise. General instructions are to do the exercises slowly and stay within pain limits. The splint is worn between exercises and at night. Only when patients understand the exercises should they do them independently at home.

Figure 40-3 In the first phase of exercises after a mallet finger injury, the amount of DIP joint flexion is controlled by using a large diameter cylinder. When the cylinder with the hand on top is rolled forward it allows some DIP joint flexion; rolling back the DIP joint is pushed into extension similar to a place-hold exercise.

Therapists should measure the active flexion and extension of the DIP joint, and if there is adequate active DIP extension, both the frequency of exercises and the range of joint motion allowed can be increased gradually. The range of flexion exercises can be increased by using a smaller cylinder. Weaning off the splint gradually and carefully increasing flexion range prevent a recurrence of the mallet finger. Most patients require close monitoring of splint wear and exercises during this phase.

Zone 3: Central Slip Lesion (Boutonnière Deformity)

Closed injuries are often missed in the acute stage because the triangular ligament initially maintains the dorsal positions of the lateral bands, helping to maintain extension of the PIP joint. Only when the triangular ligament yields and allows the lateral bands to slip volarly will the lack of PIP joint extension become apparent due to the developing boutonniere deformity.^14–16 Chronic boutonnière deformity leads to flexion contracture of the PIP joint.

For a boutonnière deformity after closed injuries, the underlying pathology is attenuation or partial disruption of the central slip and nonsurgical treatment is attempted first. The goal is to immobilize the PIP joint in extension to allow the attenuated tendons to heal. A thermoplastic splint can be used to maintain the PIP joint in full extension for 6 weeks on a full-time basis. Others prefer the PIP joint to be pinned in extension for the first 3 weeks, or even 5 to 6 weeks. The DIP joint should be free and is allowed to move actively. The immobilization by splinting should be extended beyond 6 weeks if extension lag continues to exist after initiation of PIP joint flexion. After the splint is discontinued, gradual active flexion of the PIP joint is initiated.

After surgical treatment of the persistent deformity or surgical repair of an open, complete disruption of the central slip, the goal of therapy is to protect the central slip, prevent adhesions, prevent DIP joint stiffness and extension lag, and maintain the length of the oblique retinacular ligament (ORL).

Treatment protocols include immobilization, passive early mobilization with a dynamic splint and immediate controlled active mobilization of the PIP joint.^17–19

Maddy and Meyerdiercks advocate immobilizing the PIP at 0° of extension with a static finger-based splint for 3 to weeks followed by another 3 weeks of active flexion and assisted extension with a finger-based dynamic extension splint.²⁰

The dynamic extension splint in this study was a custom-made spring coil finger-based splint, much like a Capener splint (Figure 40-4). At 3 weeks, when the dynamic splint was fabricated, a structured program with three exercises was given to the patient: active DIP flexion with the PIP blocked manually in extension, active PIP flexion with the MP blocked in extension, and composite active MP, PIP, and DIP flexion, with the splint extending the PIP joint between repetitions of each exercise.

Figure 40-4 A Capener splint for correction of PIP joint deformity.

Some authors start the early controlled mobilization using a prefabricated spring coil dynamic PIP extension splint (Capener) as early as 10 to 14 days postoperatively, following immobilization of the PIP joint in extension with a static splint.²¹ Both groups initiated active DIP flexion exercises with the PIP held in extension within the first week. However, with extensive dorsal tissue damage or severed lateral bands the DIP, exercises were postponed until 4 weeks post-operation.

Because the intent is to passively extend not against the resistance of a flexion contracture but as an assist to healing extensors, the spring coil does not need to be very strong, and a lower force type can be chosen or fabricated. The goal of the splint is to achieve maximum extension at rest with the lowest possible force and at the same time make active flexion easy to perform. The position of full PIP extension (possibly 10° of hyperextension) in both the static and the dynamic splints is critical for a successful outcome.²³

The dynamic splinting can also be hand based,^22,23 or extending across the wrist. The wrist is usually placed in 30° extension, metacarpophalangeal (MCP) joints in slight flexion, and interphalangeal (IP) joints fully extended^24,25 (Figure 40-5). The DIP joint is allowed to actively flex to release the tension on the central slip and to ensure some gliding of the intact lateral bands. During the first week of active PIP joint flexion, the PIP joint is allowed to flex up to 30° either by putting a stop on the outrigger line, by adding a volar splint or by the patient grasping a large cylinder. PIP joint flexion is increased by 15° each week.

Figure 40-5 Dynamic extension splinting after surgical repair of zone 3 extensor tendons. Here active flexion and passive extension is achieved by the dynamic traction of the extension splint.

From week 3, place-and-hold exercises for finger extension can be incorporated by passively extending the PIP joint and actively maintaining the joint at this position. The exercises are done one to two hours with 10 repetitions each session.

At week 4, active PIP joint extension is started. The patient continues to use a small finger extension splint, such as a neoprene splint, during the day to support extension. At week 5, achieving 90° of active PIP joint flexion is the goal. Starting at week 6, light activities of daily living are allowed. Resisted finger motion is started at week 8. If the PIP joint has less than 60° of passive flexion, corrective flexion splinting can be applied by bandaging the fingers in flexion for periods of 10 to 15 minutes, several times a day. We emphasize that the above program is progressed only when the patient maintains full active PIP joint extension. If the patient does not have full extension, the period of splinting in extension should be prolonged, and more emphasis should be given to extension than to flexion. Walsh and colleagues²² compared the dynamic extension splint with static splinting and the results suggested an earlier return to work with less frequent therapy visits for the dynamic extension splint group.

Early active digital extension is also used after surgical repair of the extensor tendon in this zone. This method advocated by Evans is known as Short Arc Motion.¹⁷ In the active motion protocol, for the first 4 to 6 weeks, the digit is immobilized in a finger based static splint in full extension with the MCP joint excluded. Every hour the patient is allowed to perform intermittent limited active flexion and extension exercises using a template splint (Figure 40-6). The patient actively flexes to the limits of the template splint and actively extends to full extension. The template splint supports only the PIP and DIP joints and allows for 30° active PIP and DIP joint flexion in the first 2 weeks, increasing 10° flexion each week.²⁶ Exercises are performed 4 to 6 times a day. At 6 weeks, both splints are discontinued, and exercises of full range of active motion are started.

Figure 40-6 Limited active flexion and full extension exercises of the PIP and DIP joints using a template splint.

Evans and Thompson^17,26 calculated that the amount of force added on the repair was 3 N during early active motion, which is well within the strength of most suture techniques (about 20 N in the first week)⁶ and the 30° flexion limit keeps the force within a safe zone.

Focusing on zones 2 and 3, the studies of Hung,²⁷ Saldana,²⁸ and Newport²⁹ do not support the idea that dynamic splinting has benefits over static splinting. Therefore some regard static splinting to be as effective and should be the standard care for simple extensor tendon lacerations distal to the MCP joint, given its simplicity and lower cost.

For chronic boutonniere deformity of PIP joint with a flexion contracture of over 30°, serial casting is a useful way to correct the deformity. The cast is applied to the PIP joint and is changed approximately every 2 weeks; PIP joint extension is progressively increased by 5° to 10° after each change of the cast.

A frequent complication in treating closed boutonniere deformity is incomplete correction of the deformity. However, an extension lag of about 20°, in the presence of full PIP and DIP active flexion leads to little functional disturbance of a finger, and therapy does not necessarily need to continue if these degrees of digital motion have been achieved.

Zone 4: Proximal Phalanx

In this zone, injuries to the tendon often cause no functional loss because the wide extensor hood covers more than half of the proximal phalanx. However, when the tendon is repaired, due to the large contact area to the underlying bone, it creates a substantial risk of adherence. which restricts gliding of the extensor hood. Therapists need to be aware of this extra risk and start active gliding exercises as soon as possible. Protective tendon gliding can be provided with a dynamic extension splint as in zone 3 injuries, or using gentle active exercises similar to the short arc motion method advocated by Evans.¹⁷

Zones 5 and 6: MCP Joint and Dorsum of the Hand

In zone 5, the sagittal bands are responsible for maintaining the extensor tendon central over the MCP joint. Injuries may lead to subluxation of the extensor tendon. The sagittal bands are tensed during MCP joint flexion. Following sagittal band repair, MCP joint flexion should be gentle. Flexing the IP joints while the MCP joint is kept in extension reduces tension on the sagittal bands and ensures some gliding of the tendon.

The zone 5 extensor tendon repair can adhere to the MCP joint capsule. Immobilization of the joint in extension would lead to contracture of the collateral ligaments. To prevent these complications, use of a protocol with early MCP joint flexion is beneficial.

In zone 6, the extensor tendon is more rounded than distal extensor tendons and allows stronger surgical repairs. Because of the juncturae tendinum connections between the EDC tendons on the dorsum of the hand, movements of adjacent finger(s) affect tension on the repaired tendon. When the repair site is distal to the interconnections, flexion of the adjacent digits may pull through the interconnections on the proximal stump, moving it distally, toward the distal stump, bringing the tendon ends together. Therefore, splinting the adjacent digits in slightly greater flexion or excluding the adjacent digits from immobilization and allowing them to flex, may reduce tension across the repair site. In contrast, when the repair site is proximal to the interconnections, flexion of the adjacent fingers may increase tension on the repair site so the uninjured fingers should be held in the same position in the splint. Zone 6 repairs benefit from early motion protocols as postoperative edema on the dorsum of the hand limits MCP joint flexion; early motion facilitates reducing edema.

Lacerations of the extensor tendons in zones 5 and 6 are often treated with an early motion protocol using a dynamic splint.²⁷ Within 2 to 5 days postoperatively, a dorsally based dynamic splint is applied holding the wrist in 30° to 40° extension and dynamically extending the MCP joints to full extension via an outrigger (loops around the proximal phalanx). At this time active flexion of the MCP joints is allowed to 20° to 30° for index and middle fingers, and 35° to 40° for the ring and little fingers while the IP joints are actively extended. The second exercise is to flex the IP joints while maintaining extension of the MCP joints (active hook fist). Exercises are done 5 times every 2 hours in the first 2 weeks, and after that 10 times every hour. For patients needing more support because they experience unrest during sleep or exhibit a tendency toward development of an extensor lag, a volar splint may be used to keep the fingers in extension at night. At week 2, active flexion of MCP joints is allowed to 45°, week 3 to about 60° and week 4 to 90°. At week 4, place-and-hold exercises for full finger extension are started and at week 6 the splint is discontinued. Strengthening exercises are started around week 7 and at 12 weeks the hand can be used normally. Patients are progressed on this timetable only if no extensor lag is observed.

For isolated EDC injuries in zones 5 and 6, the immediate controlled active motion (ICAM) technique can be used, as described by Howell and colleagues.³⁰ This method allows immediate active controlled motion by using a yoke splint which places the injured finger in MCP joint extension slightly greater than the adjacent fingers, and a second splint is applied to hold the wrist in 20° to 25° extension. The ICAM protocol has the following three phases: (1) Days 0 to 21—Two splints are worn full time and active composite finger flexion exercises are started. (2) Days 22 to 35—The patient continues to wear the yoke splint at all times but removes the wrist splint only for wrist exercises. (3) Days 36 to 49—The wrist splint is discontinued but the patient continues wearing the yoke splint while using the hand but removes it for active finger motion exercises. In Howell’s report 81% patients achieved excellent results for both digital extension and flexion.³⁰ Only five patients developed a lag and there were no tendon ruptures.

The Norwich regimen³¹ designed for zone 5 and 6 extensor tendon rehabilitation is an active protocol using a volar immobilization splint, which hold the wrist in 45° extension, the MCP joints in 50° flexion, and the IP joints in full extension. Two exercises are performed for 4 weeks, 4 times a day, with 4 repetitions each time (“the rule of four”). After loosening the digital straps the following exercises are performed: combined active MCP and IP joint extension (lifting the extended digits off the splint) and active MCP joint extension with IP flexion (making a hook fist within the splint) (Figure 40-7). When extension lag persists, the splint can be worn at night or part of the day, with a V-shaped insert holding the MCP and IP joints at 0° (Figure 40-8).

Related posts:

Gene Therapy for Tendon Healing Current Status and Future Primary Repair of the Flexor Pollicis Longus Tendon Molecular Biology of Tendon Healing Soft Tissue Coverage for Extensor Tendon Reconstruction Customizing Flexor Rehabilitation Based on Zone or Type of Injury

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