FOREARM, WRIST, AND HAND

CHAPTER SIX FOREARM, WRIST, AND HAND

AXIOMS IN ASSESSING THE FOREARM, WRIST, AND HAND

• Pain in the wrist and hand may have origin in the bones and joints, periarticular soft tissues, nerve roots, peripheral nerves, and vascular structures.

• Pain in the wrist and hand may also be referred from the cervical spine, thoracic outlet, shoulder, or elbow.

INTRODUCTION

Chronic wrist pain has often been called the lower back pain of hand conditions. Both areas offer the clinician significant diagnostic and therapeutic challenges. As in the examination of the lower back, a precise evaluation based on thorough knowledge of regional anatomy is essential to successful management (Table 6-1).

TABLE 6-1 FOREARM, WRIST, AND HAND CROSS-REFERENCE TABLE BY ASSESSMENT PROCEDURE

The wrist joint is probably the most complicated joint in the body because of its unique arrangement and articulation of the radiocarpal and intercarpal joints. Ligamentous injuries to the carpus can lead to significant and possibly permanent disability. Diagnosis may be difficult with persistent degrees of carpal instability. Definitive treatment modalities have not been perfected. As with most joint injuries, a more thorough understanding of the anatomy and pathogenesis of these injuries is useful (Table 6-2).

TABLE 6-2 PRINCIPAL DIFFERENTIAL DIAGNOSIS LIST FOR WRIST PAIN

Radial side	Tenosynovitis (de Quervain disease)
	Osteoarthritis of first carpometacarpal joint
	Scaphotrapeziotrapezoid osteoarthritis
	Scaphoid non-union
	Ganglion
Dorsal, central	Kienböck disease
	Scapholunate dissociation
	Scapholunate advanced collapse (SLAC wrist)
	Intraosseous ganglion
	Ganglion
Ulnar side	Ulnar abutment syndrome
	Ulnar impaction syndrome
	Distal radioulnar joint degenerative arthritis/instability
	Ulnar head chondromalacia
	Triangular fibrocartilage complex tear
	Extensor carpi ulnaris tendonitis/subluxation
	Lunotriquetral instability
	Pisotriquetral joint disease
	Midcarpal instability

Adapted from Ankarath S: Chronic wrist pain: diagnosis and management, Curr Orthop 20(2):141-151, 2006.

Carpal injuries represent a spectrum of bony and ligamentous damage. The names given to the various injuries describe the resultant damage apparent only on radiographs, for example, lunate dislocation, perilunate dislocation, scaphoid fracture, transscaphoid perilunate fracture-dislocation, and transscaphoid transtriquetral perilunate fracture-dislocation. Each injury is not an entity but part of a continuum.

A stable and pain-free wrist is a prerequisite for normal hand function. In contrast, a painful, unstable, or deformed wrist impairs function. The wrist, a common target of rheumatoid arthritis, is adversely affected by the reaction of synovial tissue on capsuloligamentous structures, articular cartilage, and subchondral bone. The mechanical forces of the different muscle groups acting across the wrist also contribute to deformities.

TABLE 6-3 FOREARM, WRIST, AND HAND CROSS-REFERENCE TABLE BY SYNDROME OR TISSUE

Anterior interosseous syndrome	Pinch grip test
Arterial stenosis	Allen test Tourniquet test
Aseptic necrosis	Finsterer sign
Carpal fracture	Carpal lift sign Cascade sign Finsterer sign
Carpal tunnel syndrome	Phalen sign Tinel sign at the wrist Tourniquet test Wringing test
Colles fracture	Maisonneuve sign
Denervation	Dellon moving two-point discrimination test Shrivel test Weber two-point discrimination test
Digit contractures	Bunnell-Littler test Test for tight retinacular ligaments
Neuroma	Interphalangeal neuroma test
Rheumatoid arthritis	Bracelet test Cascade sign
Sprain	Carpal lift sign
Tenosynovitis	Finkelstein test
Ulnar neuropathy	Dellon moving two-point discrimination test Froment paper sign Tinel sign at the wrist Tourniquet test Wartenberg sign Weber two-point discrimination test

The initial evaluation of a patient with an injured wrist must be thorough and methodical. In recent years, increased understanding of carpal mechanics and instability patterns, with and without fractures, has increased the importance of accurate examination of the wrist. The diagnosis of sprained wrist is not adequate in establishing a proper treatment regimen. By taking a complete history, performing an exact examination, and using appropriate diagnostic aids such as motion views, tomography, bone scans, and arthrography, the clinician can establish an accurate diagnosis of wrist injury. Only after an accurate diagnosis is established can a rational, therapeutic regimen be prepared.

As with any other orthopedic problem, assessment of wrist and hand disorders begins with a complete history (Box 6-1). Painful disorders of the forearm, wrist, and hand can be classified based on the tissue of origin of pain and its distribution.

ESSENTIAL ANATOMY

The bones of the hand can be divided into four units: a central fixed unit for stability and three mobile units for dexterity and power. The fixed unit is composed of eight carpal bones tightly bound to the second and third metacarpals.

The wrist transmits force between the hand and forearm. Force passes through the capitate bone of the distal carpal row, the scaphoid and lunate bones of the proximal carpal row, and onward proximally to the distal end of the radius. These bones are the ones most likely to be fractured or dislocated in injury of the hand-wrist mechanism. Of the two long bones of the forearm, only the radius has true articulation with the carpal bones. The carpal fractures often involve the scaphoid. Scaphoid fractures, with typical tenderness at the anatomic snuffbox, can result in chronic wrist pain because of non-union or collapse of the structure following injury. Wrist radiocarpal trauma can also involve the triangular fibrocartilage complex (Table 6-4).

TABLE 6-4 TRIANGULAR FIBROCARTILAGE COMPLEX INJURY CLASSIFICATION

ESSENTIAL MOTION ASSESSMENT

Movements of the wrist comprise flexion, extension, and ulnar and radial deviation. Flexion-extension movements of the fingers occur at both the metacarpophalangeal (MCP) and the interphalangeal joints (Fig. 6-1).

FIG. 6-1 Examples of thumb movements. A, Flexion-extension. B, Abduction-adduction. C, Opposition.

Movements of the thumb are described in terms different from those applied to the other digits because the thumb is positioned in a way that is different from the way the fingers are positioned, and the thumb is capable of unique movements not possible in the other digits.

Opposition is a unique capability, possessed only by the thumb. The goal of opposition is to cause the pulp surface (i.e., the rounded eminence directly opposite the nail) of the distal phalanx to face the pulp surfaces of the other digits. This capability is essential to realizing the full range of capabilities for grasping and manipulating objects with the hand.

Creating a cup-shaped recess in the palm of the hand requires movement of the other four digits. This recess allows an object to be cradled in the palm before the fingers are closed over it.

For examination of the wrist-hand range of motion, the middle finger is considered midline (Fig. 6-2). Wrist flexion decreases as the fingers are flexed. Movements of flexion and extension are ultimately limited by muscles and ligaments (Figs. 6-3 and 6-4).

FIG. 6-2 Range of motion of the hand and wrist.

FIG. 6-3 The wrist in a neutral position. Radial deviation of 15 degrees or less and ulnar deviation of 30 degrees or less.

FIG. 6-4 A, The wrist in a neutral position. B, Wrist flexion. C, Wrist extension (dorsiflexion).

Finger abduction is 20 to 30 degrees at the MCP joints. Finger adduction is 0 degrees at the same joint. The loss of finger abduction or adduction has minimal effect on the activities of daily living. Thumb flexion at the carpometacarpal joint is in a range of 45 to 50 degrees. At the MCP joint, the range is 50 to 55 degrees. At the interphalangeal joint, thumb flexion is in a range of 80 to 90 degrees. Extension of the thumb at the interphalangeal joint is 0 to 5 degrees. Thumb abduction is 60 to 70 degrees. Thumb adduction is 30 degrees. Seventy degrees or less of retained flexion of the thumb at the interphalangeal joint and 50 degrees or less retained flexion at the MCP joint are considered impairments of the thumb in the activities of daily living. Zero degrees of extension at the interphalangeal joint is considered the sole impairment of extension for the thumb. Forty degrees or less of radial abduction and 25 degrees or less of adduction are considered impairments of the thumb in the activities of daily living (Fig. 6-5).

FIG. 6-5 Finger flexion (A) at the MCP joints. Extension (B) at the MCP joints. Retained active finger flexion of 80 degrees or less at the MCP joint, 90 degrees or less at the proximal interphalangeal joint, and 60 degrees or less at the distal interphalangeal joint serve as an impairment of the fingers in the activities of daily living. Retained active extension of 10 degrees or less at the MCP joint serves as the sole impairment of the fingers in the activities of daily living.

ESSENTIAL MUSCLE FUNCTION ASSESSMENT

ORTHOPEDIC GAMUT 6-4 MUSCLES OF THE HAND

Muscles controlling movements of the hand are divided into two groups:

1. Extrinsic muscles that originate within the arm and forearm

2. Intrinsic muscles, the origins and insertions of which are entirely within the hand (Figs. 6-6 to 6-10)

FIG. 6-6 Flexion. The patient flexes the wrist against graded resistance provided by the fingertips of the examiner’s other hand placed in the patient’s palm.

FIG. 6-7 Extension. The patient extends the wrist against graded resistance applied by the examiner’s other hand to the dorsal surface of the patient’s metacarpals.

FIG. 6-8 Flexion of the interphalangeal joints of the fingers is accomplished by the long flexor tendons.

FIG. 6-9 The intrinsic muscles of the hand consist of a central group containing the interossei and lumbricales and the two lateral groups of hypothenar and thenar eminences.

FIG. 6-10 The interosseous and lumbrical muscles are of fundamental importance in the extension of the fingers.

ALLEN TEST

Assessment for Peripheral Vascular Obstruction at the Wrist

Comment

Diagnosis of reflex sympathetic dystrophy–complex regional pain syndrome (RSD-CRPS) is initially based on clinical symptoms and signs for the upper extremity, which includes painful disuse of the hand and wrist with a high degree of awareness. Supportive laboratory testing includes positive bone scans, hypervascularity (thermography), and positive sweat test with autonomic dysfunction and quantitative sudomotor axon reflex test. Later, osteoporosis can help confirm the diagnosis. The sympathetic dystrophy scale is effective in confirming and rating the severity of this syndrome (Boxes 6-2 and 6-3).

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Jun 5, 2016 | Posted by admin in ORTHOPEDIC | Comments Off

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