Orthoses for Tendon Management

Learning Outcomes

Upon completion of this chapter, you will be able to:

1. Describe the healing process for flexor and extensor tendons following surgical repair.

2. Describe the orthoses used for flexor and extensor tendon rehabilitation.

3. Identify pertinent anatomical structures and biomechanical principles involved in the fabrication of a dorsal blocking orthosis and apply concepts to orthotic design and fabrication.

4. Design patterns for orthoses for flexor tendon and extensor tendon rehabilitation protocols.

5. After reviewing the instructional videos:

a. Outline the steps involved in the fabrication of a dorsal blocking orthosis.

b. Outline the steps involved in the fabrication of a relative motion orthosis.

c. Complete the molding and fabrication steps of the above orthoses.

d. Evaluate the fit and function of a completed orthosis for flexor or extensor tendon management and identify and address all areas needing adjustment.

6. Identify elements of a client education program following provision of a dorsal blocking and relative motion orthosis.

Introduction

Specialized rehabilitation protocols, including custom orthoses, are necessary following injury and surgical repair of the extrinsic flexor and extensor tendons due to the intricate anatomical structures through which these tendons move and glide. Tendon injuries on the volar and dorsal hand and forearm are commonly associated with concurrent soft tissue injury and postoperative edema and require proper surgical technique and supervised therapeutic interventions, including specific orthotic designs. This chapter will provide a brief discussion on flexor and extensor tendon anatomy and tendon healing, biomechanical principles, and the common rehabilitation approaches used following tendon injury and repair. Readers are encouraged to seek additional resources on tendon injuries and postoperative management.

Tendon Anatomy and Healing

A thorough understanding of tendon anatomy, wound-healing principles, and the importance of controlled movement and stress application to a healing tendon is critical. In order for the practitioner to optimize functional outcomes following repair of tendon injuries, several factors must be considered, including the design, fabrication, application, and modification of orthoses used during rehabilitation. These principles should also be considered throughout the recovery period because the client’s condition may change and require additional interventions.

FLEXOR TENDON ANATOMY

The flexor tendons in the hand enter the hand under the transverse carpal ligament, within the carpal tunnel. The four tendons of the flexor digitorum profundus (FDP) lie deep to the four tendons of the flexor digitorum superficialis (FDS) and the flexor pollicis longus (FPL) tendon. The FDP tendons continue deep to the FDS tendons in the palm and digits. The FDS tendon splits into two slips at the level of the proximal phalanx, and both slips converge to insert onto the base of the middle phalanx. The FDP runs between the two slips of the FDS and courses distally and inserts onto the base of the distal phalanx. The FDS flexes the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints; the FDP flexes the distal interphalangeal (DIP) joint and assists in PIP and MCP joint flexion. The FPL is part of the deep layer of muscles in the forearm and is the sole muscle that flexes the thumb interphalangeal (IP) joint.

As the FDS and FDP run under the transverse carpal ligament and into the palm from their origin in the forearm, they are surrounded by a synovial bursa. This bursa is filled with synovial fluid that provides lubrication and nutrition to the tendons and allows the tendons to glide without friction. In the digits, the FDS and FDP run together in a synovial sheath that is surrounded by a series of pulleys (see Figure 2-31). These pulleys position the FDS and FDP close to the axis of joint motion during active movement and optimize flexion of the PIP and DIP joints. If the pulleys are damaged, they might also need surgical repair, and therapists will fabricate a “pulley ring” of thermoplastic material to protect this repair. The A2 and A4 pulleys have been identified as being the most important to prevent bowstringing of the tendons, and these may be repaired when injured, requiring additional protection.

EXTENSOR TENDON ANATOMY

Chapter 2 provides a detailed description of extensor tendon anatomy from the fingertips proximally to the MCP joints (zones I through IV). This section will describe the anatomy of the extensor tendons in zones V through VII (Figure 10-1; Box 10-1).

The extrinsic extensor tendons to the digits and thumb run on the dorsal aspect of the wrist under the extensor retinaculum (see Chapter 1) and course distally to the digits. These include the extensor digitorum (ED), extensor indicus proprius, extensor digiti minimi, extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus. The wrist extensors also run under the extensor retinaculum and include the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris.

The juncturae tendinum (tendinous slips that connect the ED tendons) are located just proximal to the MCP joints and help to stabilize the ED tendons over the MCP joints during active finger flexion and assist in extension of adjacent digits. These structures are important to consider when designing orthoses following extensor tendon repair.

ZONES OF INJURY

The volar and dorsal aspects of the hand and wrist are divided into distinct flexor and extensor tendon zones of injury. There are five flexor zones and seven extensor zones. These zones help identify locations of the specific anatomical structures and help guide the practitioner in determining the most suitable rehabilitation regime for the client, including the type and design of the orthosis needed. For flexor and extensor zones, the odd-numbered zones are located over joints (DIP, PIP, MCP, and wrist), and the even-numbered zones over the shafts of the bones (distal, middle, and proximal phalanges; metacarpals; radius and ulna).

TENDON HEALING

After surgical repair, tendons heal by two primary means: intrinsic and extrinsic healing. Intrinsic healing occurs as a result of nutrition from the synovial fluid surrounding the tendon within the sheath and formation of new tendon cells at the repair site. Extrinsic healing occurs as a result of blood supply from the vincula (small vessels arising from the digital arteries) and deposition of collagen cells on the outside of the tendon at the repair site. The application of early controlled movement of a tendon following repair is thought to facilitate intrinsic healing and limit the amount and organization of collagen deposition at or near the repair site, thus minimizing adhesion development.

Tendon healing can be classified in three stages: early, intermediate, and late. The strength of the tendon repair (the amount of force the tendon can withstand without rupture), referred to as tensile strength, is at its weakest from 0 to 3 weeks following repair (early stage) and becomes progressively stronger from weeks 3 to 6 as more collagen is laid down at the repair site (intermediate stage). It is not until the late stage (week 12 and beyond) that the tendon can withstand normal tensile forces. It is during this phase that the tendon continues to remodel in response to the forces placed on it. Collectively, the first 3 weeks should be aimed at protecting the tendon from undo stress and excessive movement, followed by more controlled stress (initiation of active movement to increase excursion and force) on the tendon from weeks 3 to 6. Six weeks post-tendon repair and beyond is characterized by progressive tendon gliding exercises and graded application of resistance to facilitate remodeling and improve tensile strength.

Goals for Use of Orthoses Following Tendon Injury and Repair

The goal of an orthosis following injury and repair of either a flexor or extensor tendon will vary depending on the individual client and his or her condition, the physician orders, and the expected functional outcomes. Box 10-2 presents a summary of the goals of orthotic intervention following tendon repair.

Tendon Rehabilitation Approaches

Thorough knowledge of the different rehabilitation protocols that are typically used following surgical tendon repair is essential to a practitioner when fabricating an orthosis as part of a tendon rehabilitation program. In particular, the practitioner must know the location or zone of injury (see discussion earlier in this chapter), the strength of the repair, the number of suture strands used at the repair site, and involvement of other structures such as a nerve or artery. Close communication with the referring surgeon is essential to guide the rehabilitation program and optimize the client’s outcomes. Further, the practitioner must account for specific client factors that may influence the rehabilitation regime chosen (e.g., age, presence of edema, wound-healing complications, ability to adhere to a strict rehabilitation protocol, or injury to other structures) and adjust the orthosis and regime components accordingly.

FLEXOR TENDON PROTOCOLS

This section describes the three most common rehabilitation protocols used following flexor tendon injury and repair. Orthotic intervention is critical following repair in all zones of injury. Although the protocols differ, the design of the orthosis used is essentially the same. The differences are as follows:

• The position of the joint(s) in the orthosis
  
• The length of time the orthosis is used
  
• The exercises the client performs within the orthosis

Typically, the client will be seen in the first week following surgery. The bulky postoperative bandaging is removed by the clinician, and wound care needs are addressed. Then, new dressings are applied and kept in place with a stockinette sleeve. The low-temperature thermoplastic material (LTTM) orthosis can be molded directly over this sleeve (Figure 10-2A through D).

Immobilization

Immobilization is a protocol that is typically used for children younger than 10 years and for those clients who cannot adhere to a detailed rehabilitation regime due to impaired cognition or other factors that may affect compliance. The affected hand and wrist are immobilized in a dorsal blocking orthosis or extension restriction orthosis with the wrist, MCP, PIP, and DIP joints included for 3 to 4 weeks. The wrist is positioned between 0 and 10 degrees of extension (check with referring physician), the MCP joints at 40 to 50 degrees of flexion, and the PIP/DIP joints in extension (Figure 10-3). A custom orthosis or a cast may be used, depending on the client’s particular needs. Following the initial immobilization period, the orthosis may be modified to bring the wrist to neutral or slight extension, and passive and/or active tendon gliding exercises can begin (Table 10-1). Development of adhesions (scar tissue at the site of repair, causing loss of gliding and movement of the involved tendon[s] and joint stiffness) is common during the immobilization period, especially if there is concurrent injury to other structures such as a bone fracture.

Early Passive Motion

Early passive motion is an approach that was developed over 35 years ago in an attempt to address the frequent development of dense adhesions specifically within zone II (see Box 10-1). This approach involves early passive movement of the repaired tendon(s) to minimize development of scar adhesions and facilitate tendon healing. This protocol was initially based on the theory that 3 to 5 mm of tendon gliding and excursion can decrease the risk of adhesion development. The Kleinert and modified Duran protocols are based on this theory. A dorsal blocking, extension restriction orthosis is used with the wrist in 10 degrees of extension (wrist position may depend on the surgeon’s preference), the MCP joints at 50 degrees of flexion, and the PIP/DIP joints in full extension. The client performs passive digit flexion exercises within the orthosis 10 to 20 times per hour during the day (see Table 10-1). The Modified Duran protocol uses a strap to position the IP joints in extension between exercises and at night. The Kleinert protocol also includes elastic traction on the involved digit(s) that holds the digit(s) in flexion, and the client performs active extension against the resistance of the elastic traction followed by passive flexion (Figure 10-5). Although both protocols are used in current clinical practice, the Modified Duran protocol is generally favored over the Kleinert protocol due to the heightened risk of PIP flexion contractures with the latter regime. The choice of rehabilitation approach ultimately depends on the referring surgeon’s preference.

Early Active Motion

Early active motion is an approach to tendon rehabilitation that differs from both the early passive motion and immobilization regimes. The most notable difference is initiation of early active contraction of the muscle-tendon unit to achieve more natural gliding and excursion at the repair site. This regime requires a strong surgical repair (at least four strands, sometimes six), an experienced practitioner, a motivated and compliant client, and minimal edema. Clients who present with concurrent injury to other structures (such as a fracture, nerve, or artery) are generally not suitable candidates for this protocol. It is ultimately the referring surgeon’s decision to initiate active motion following tendon repair. A variety of orthoses are used with this approach. The easiest and most common is a dorsal blocking orthosis with the wrist positioned in neutral to slight extension, the MCP joints at 50 to 60 degrees of flexion, and the PIP/DIP joints in full extension (see Figure 10-3). The client performs prescribed active and passive exercises within the orthosis and removes it for tenodesis exercises (Figure 10-6). Another protocol features a hinged dorsal blocking orthosis, which allows limited movement at the wrist. This enables the client to perform the tenodesis exercises within the orthosis (Figure 10-7).

Evidence

Level III

• Frueh, F. S., Kunz, V. S., Gravestock, I. J., Held, L., Haefeli, M., Giovanoli, P., & Calcagni, M. (2014). Primary flexor tendon repair in zones 1 and 2: Early passive mobilization versus controlled active motion. Journal of Hand Surgery, 39(7), 1344-1350.
  
  
  
  • This retrospective study compared flexor tendon repairs in zones I and II using early passive mobilization and early active motion protocols. A total of 159 digits were available for analysis. A statistically significant difference was found in the total active motion group at 4 weeks. At 12 weeks, however, there was no significant difference between the groups in total active motion. The authors recommend further study to examine whether faster return of motion is associated with return to work earlier as compared with the early passive motion protocol.

Level IV

• Starr, H. M., Snoddy, M., Hammand, K. E., & Seiler, J. G. (2013). Flexor tendon repair rehabilitation protocols: A systematic review. Journal of Hand Surgery, 38, 1712-1717.
  
  
  
  • This systematic review analyzed 34 studies of flex- or tendon rehabilitation protocols ranging from Level I to IV. Orthoses were used in each study. Wrist flexion ranged from 0 to 30 degrees and MCP flexion from 40 to 90 degrees, and PIP/DIP was in full extension. Wearing time ranged from 3 to 6 weeks. Early passive motion protocols had reduced risk of tendon ruptures but higher risk of adhesions and decreased joint motion as compared with early active motion protocols. Combining elements of each protocol to optimize outcomes is common practice. With better suture technique and more defined rehabilitation protocols, the authors note that early active motion may provide more optimal outcomes with better postoperative motion.

EXTENSOR TENDON PROTOCOLS

This section describes the three common rehabilitation regimes and orthoses that can be used following injury and surgical repair of extensor tendon injuries in zones V through VII: immobilization, early passive extension, and controlled active extension using the relative motion orthosis. Orthoses used for zones I through IV are discussed in Chapter 9.

Immobilization

The immobilization approach, similar to that used with flexor tendon injuries, may be used in instances where a more complicated mobilization approach is not appropriate, such as with young clients, clients with cognitive deficits, or where compliance is a concern. Evidence does suggest that these injuries can tolerate immobilization well, but recovery and return to full function may take longer as compared with a regime that involves early tendon mobilization. An orthosis (either an immobilization orthosis or a dynamic orthosis) may be used to immobilize the wrist and involved digit(s). The position of the joints in the orthosis can vary according to surgeon preference, location of the repair, and concurrent injury to other structures, such as bone, ligament, or nerve. The orthosis is typically worn for 4 weeks full-time, with intermittent wear during the day and at night for an additional 2 to 4 weeks.

Related posts:

Orthotic Fabrication: Principles and Practice Orthoses for Mobilization The Basics Wrist Immobilization Orthoses Wrist and Hand Immobilization Orthoses Anatomical and Biomechanical Principles of Orthotic Intervention

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