Anatomy of the hand and upper extremities

The many specialized structures of the hand and upper extremity work in intimate synchrony to provide a harmonious interplay of precision motor biomechanics with fine tactile senses. Owing to the intricate nature these structures, there are often several components to hand stiffness and scar contracture. To appropriately treat any hand injury, one must understand each component’s involvement.

The skin of the hand is a complex organ that not only covers the underlying structures but also has specialized functional and sensory components. The glabrous palm skin can withstand shear forces and provides fine tactile sensation, whereas the dorsal skin remains mobile and permits a wide range of motion in the wrist and digits. The periarticular stabilizing structures are essential to normal joint function. These ligamentous structures, however, are prone to contracture with even limited periods of immobilization. The volar plate, collateral ligaments, tendon sheaths, and intrinsic muscles all contribute to this process. In addition, any decrease in excursion of gliding or mobile tissues, such as tendons, can result in significant compromise. Splinting, edema control, and early motion guided by hand therapy are the key to the prevention and treatment of contractures of the hand and upper extremity.

At the core of hand function is the bony support and articular surfaces. Any fractures or articular injury can lead to tendon imbalance, alteration of joint biomechanics, and mechanical obstruction. Proper treatment and healing is necessary to allow early range of motion and hand therapy. Both are keys in preventing and treating soft tissue contraction and subsequent contracture.

Joints are the areas of greatest motion in the hand. The metacarpal phalangeal (MCP) joint is a condyloid joint with three planes of motion, including flexion or extension, adduction or abduction, and rotation. The collateral ligaments arise dorsal to the axis of rotation, and with the volar flare of the metacarpal head, provide a cam effect. Thus, there is the least amount of joint space and the most stretch on the collateral ligaments during flexion and the greatest amount in extension. Swelling increases the volume of fluid within the joint and forces the MCP joint into extension in which the collateral ligaments contract to their shorter position and make flexion difficult. Following acute trauma, therefore, the MCP joint should be splinted in flexion to prevent collateral ligament contracture.

The proximal interphalangeal (PIP) joint is a hinge joint with 0° to 100° of flexion. Here, the collateral ligament originates at the center of rotation, so there is no Cam effect and tension is equal throughout the arc of motion ( Fig. 1 ). The accessory collateral ligament inserts onto the volar plate, so there is the least amount of joint space and the most stretch on the ligaments during extension. The volar plate is also at greatest stretch during extension of the PIP joint. The PIP joint should be splinted in extension following acute trauma or in conditions of acute or chronic swelling.

A contracture of the proximal interphalangeal joint that involves soft tissue, but may also involve volar plate and collateral ligament contracture.

Initial examination for hand and upper extremity injury

The history and cause of the injury are important in assessing the potential structural involvement and previous interventions. This will provide the framework in which to begin treatment. Also important is the patient’s medical and social history, which may reveal potential factors contributing to wound healing problems and increased scar propensity Box 1 .

The physical examination of the scarred hand and upper extremity involves a systematic evaluation. The neurovascular status should be examined throughout the able range of motion. Structural integrity is also assessed, first clinically by deformity, palpation, tenderness, and then radiographically though radiograph, CT scanning, and angiography, as necessary. Most important in the secondary scar release is a functional assessment, including a detailed motor and sensory examination. First, passive and active ranges of motion are evaluated. A greater composite range of motion is required on the ulnar aspect of the hand for power grip, while less can be tolerated in the thumb and index and long fingers where key pinch is required. Initially, an assessment of the skin should be performed and any areas of tightness or limited mobility documented. Next, testing of intrinsic tightness with the Bunnell-Francescetti intrinsic tightness test will elucidate the cause of any additional limitations in range of motion, such as intrinsic or extrinsic musculotendinous tightness. This test assesses the MCP motion’s effect on PIP motion. If PIP motion is improved with MCP flexion, the test is positive for intrinsic tightness. If PIP motion is improved with extension, the limitation can be attributed to the extrinsic extensors.

Initial examination for hand and upper extremity injury

The history and cause of the injury are important in assessing the potential structural involvement and previous interventions. This will provide the framework in which to begin treatment. Also important is the patient’s medical and social history, which may reveal potential factors contributing to wound healing problems and increased scar propensity Box 1 .

The physical examination of the scarred hand and upper extremity involves a systematic evaluation. The neurovascular status should be examined throughout the able range of motion. Structural integrity is also assessed, first clinically by deformity, palpation, tenderness, and then radiographically though radiograph, CT scanning, and angiography, as necessary. Most important in the secondary scar release is a functional assessment, including a detailed motor and sensory examination. First, passive and active ranges of motion are evaluated. A greater composite range of motion is required on the ulnar aspect of the hand for power grip, while less can be tolerated in the thumb and index and long fingers where key pinch is required. Initially, an assessment of the skin should be performed and any areas of tightness or limited mobility documented. Next, testing of intrinsic tightness with the Bunnell-Francescetti intrinsic tightness test will elucidate the cause of any additional limitations in range of motion, such as intrinsic or extrinsic musculotendinous tightness. This test assesses the MCP motion’s effect on PIP motion. If PIP motion is improved with MCP flexion, the test is positive for intrinsic tightness. If PIP motion is improved with extension, the limitation can be attributed to the extrinsic extensors.

Treatment of scar contracture

The initial treatment of any soft tissue scar contracture is optimization through nonoperative management and aggressive physical therapy. The nonoperative interventions include scar massage, compression therapy, silicon sheeting, static or progressive casting, steroid injection, assisted range of motion, and a variety of orthosis techniques, such as serial casting. Surgical intervention is discussed when no additional improvement is expected with the conservative methods. Typically soft tissue equilibrium has been achieved for at least 6 months.

Surgical intervention

The goal of procedures designed to release contractures of soft tissue are to improve the motion, sensibility, durability and overall function of the hand. The contracture release procedures should be timed appropriately with consideration given to other potential interventions that may require splinting or immobilization that may interfere with the release. Attempting to address too much in one stage carries a significantly higher risk of postoperative pain, edema, and poor outcomes. The most common releases permit extension of the digits, wrist, elbow, or axilla, widening of the first web space, resurfacing of unstable scars, or restoring a sensate pad to finger tips.

Excision and skin grafting

Scar incision or excision may result in a significant soft tissue defect that extends beyond the capacity of local flaps. Skin grafts are often used to cover the wound bed following scar excision. Full-thickness grafts are usually used on the volar aspect of the hand to limit the recurrence of contractures.

Transposition flaps

Many minor or moderate contractures can be corrected with local skin flaps, avoiding the need for skin grafts or more extensive procedures. Transposition flaps are commonly used to correct these contractures. Z-plasties are normally oriented at 60° for each limb, which provides a 75% increase in length of the central limb; however, many angle modifications exist ( Fig. 2 ). The larger the angle at the apex of the Z-plasty, the more gain in length is achieved in the contracture release. The increase in this angle, however, puts greater the tension on closure and greater is laxity needed in the perpendicular plane. It is often better to use multiple Z-plasties in sequence ( Figs. 3–5 ). When the two limbs are unequal or nonparallel, it is more properly called a transposition flap.

Z-plasty is one of the standard transposition flaps used to lengthen and breakup scar tissue allowing release of contractures. The classic Z-plasty is 60°, lengthening the area of contracture by approximately 75%.

Multiple Z-plasties can be arranged in a row of even greater length.

( A – E ) A 27-year-old man who sustained a significant burn to his torso and developed contractures in the anterior axillary line. Multiple Z-plasties were planned, transposed, and imbedded unimpaired to improve range of motion.

A flexion contracture in a 19 year old male as are result of a previous burn to his hands. ( A ) Following multiple z-plasty ( B ) the digit was able to be actively extended and flexed in normal range ( C, D ).

Square, double, 4-flap, 5-flap, 6-flap ( Fig. 6 ), and jumping man ( Fig. 7 ) Z-plasties are all modifications of this procedure and are demonstrated below with additional information on length gain Table 1 .

( A , B ) Multiple Z-plasties can be arranged to provide greater length or take advantage of laxity of soft tissue in the area. Areas of contour similar to a saddle, such as the first web space and axilla, are particularly amendable to these types of flaps.

Opposing z-plasties are arranged in a jumping man fashion. ( A ) This type of flap is useful for saddle shape areas such as the first web space or axilla ( B ).

Table 1

Z-plasty types and theoretical gains in length

Theoretical Increase in Central Limb for Various Z-Plasties
Type of Z-Plasty	Percentage Increase in Central Limb (%)	New Length of Central Limb a (cm)
Simple Z-plasty with 45°	50	1.5
Simple Z-plasty with 60°	75	1.75
Simple Z-plasty with 75°	100	2
4-flap Z-plasty with 45°	100	2
4-flap Z-plasty with 60°	150	2.5
6-flap Z-plasty with 45°	150	2.5
Double-opposing Z-plasty	75	1.75
2 Z-plasties in series	75	1.75
5-flap Z-plasty	125	2.25

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