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).

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 tunnel syndrome Colles fracture Maisonneuve sign Denervation Digit contractures Neuroma Interphalangeal neuroma test Rheumatoid arthritis Sprain Carpal lift sign Tenosynovitis Finkelstein test Ulnar neuropathy

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

Class I: Traumatic

A. Central perforation B. Ulnar avulsion a. With distal ulnar fracture b. Without distal ulnar fracture C. Distal avulsion D. Radial avulsion a. With sigmoid notch fracture b. Without sigmoid notch fracture

Class II: Degenerative (ulnocarpal abutment syndrome)

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).

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).

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).

ESSENTIAL MUSCLE FUNCTION ASSESSMENT

ESSENTIAL IMAGING

The importance of routine posteroanterior and lateral radiographs in neutral position of the wrist cannot be overemphasized.

ALLEN TEST