Figure 12.1
The carpal bones of the wrist
Introduction
The wrist and hand are extremely important for normal everyday functional living. Their extensive range of motion enables us to perform a variety of complex tasks, including notably object handling and communicating, and providing oppositional grip.
Anatomically, the hand and wrist comprise a complex system of static and dynamic structures – bones, muscles, tendons, ligaments and skin. These components have complex relationships with each other to allow and maintain variable mobility (Rhee et al 2006). The ‘wrist joint’ is not a single joint but a complex of radiocarpal, intercarpal, mid-carpal and carpal–metacarpal joints.
A common condition, and the most common peripheral nerve entrapment in the wrist, is carpal tunnel syndrome (Alfonso et al 2010). This is a compression and/or entrapment of the median nerve as it traverses through the carpal tunnel that causes impairment of motor and/or sensory nerve conduction, resulting in symptoms such as numbness, pain and paresthesia. It has a higher incidence in the elderly population, is more common in females than males (Newport 2000), and it can be associated with medical conditions such as diabetes, rheumatoid arthritis, hypothyroidism, renal disease and pregnancy (Katims et al 1989, Maghsoudipour et al 2008, Barcenilla et al 2012, O’Connor et al 2012). There is also evidence for an association with obesity and smoking (Becker 2002, Geoghegan et al 2004). Although there remains a lack of detailed understanding of its interconnection with occupation, some studies have hypothesized that 50% of all carpal tunnel syndrome presentations are connected to occupation (Dale et al 2013). Abbas et al (1998) and Palmer et al (2007) found that occupations that involve prolonged repetitious dorsiflexion/palmar flexion of the wrist and the operation of handheld vibration tools had high incidences, for example.
The total available evidence suggests that carpal tunnel syndrome can be associated with factors such as occupation, lifestyle and medical history, but that a person is more likely to develop it when multiple factors are present.
There have been a number of studies into the effectiveness of manual therapies in the treatment of carpal tunnel syndrome (e.g. Heebner & Roddey 2008, McKeon & Yancosek 2008, Carlson et al 2010). These have looked at articulation of the wrist and carpal bones, splinting and neural gliding, but the research to date is inconclusive: some have found that in mild presentations manual therapy has had beneficial results (Burke et al 2007, Meems et al 2014), while others have stated that there is no statistical evidence for this (Huisstede et al 2010, Page et al 2012). Although a recent paper by Meems and colleagues (2014) stated that traction of the wrist may be an alternative, if not yet fully evaluated, treatment option for carpal tunnel syndrome, the main medical approach is either corticosteroid injections or surgery to the palmar retinaculum to release the median nerve. The ‘gold standard’ approach is obviously, when possible, to address the mechanical cause of the carpal tunnel syndrome, whether work ergonomics, occupational causes or hobby, and then the use of night splints coupled with a structured manual therapy approach to the hand, wrist and upper extremity. If this does not succeed, surgery is possibly the best course of treatment.
Villafañe et al (2013) examined the effectiveness of manual therapy and exercise for osteoarthritis in the carpometacarpal joint and discovered that a combination of articulation, neural articulation and exercise was more effective than a sham intervention, although they acknowledged that further research is required.
A study by Rabin et al (2015) found that three out of four participants with De Quervain syndrome reported better reduction in symptoms with manual articulation, muscle training and electrical stimulation compared to corticosteroid injections. A case study by Walker-Bone and colleagues (2004) of a patient with radial wrist pain, which had been diagnosed 2 years before as De Quervain’s syndrome, found that manual therapy of the hand and wrist decreased the patient’s reported pain over a period of 4 weeks.
Van Tulder et al (2007) found that manual therapy, combined with exercise therapy and self-help advice, can be beneficial for repetitive strain injuries such as tenosynovitis and wrist impingement conditions, although the studies they reviewed were not large enough to be statistically significant.
Anatomy
Bony and joint anatomy
The hand is made up of 27 bones, which are divided into two groups: the carpus, containing 8 carpal bones that form the wrist and base of the hand, and the digits, comprising 5 metacarpals and 14 non-sesamoid bones of the phalanges. The wrist acts as a bridge between the forearm and the hand. In addition to the carpal bones, it comprises the proximal areas of the metacarpal bones and the distal ends of the ulna and radius. All of these bones take part in complex articulations, which enable a variety of movement of the hand and wrist (Taylor & Schwarz 1955).
Carpals
The carpal bones are pebble-like structures aligned in two rows – proximal and distal – of four each. The proximal row is located very close to the distal radius and represents an intercalated segment. It includes the scaphoid (boat-shaped), lunate (moon-shaped), triquetrum (three-cornered) and pisiform (pea-shaped). These bones are held together as a group by ligaments. The scaphoid, lunate and triquetrum contribute to the radiocarpal joint. The pisiform does not participate in the kinematics of the proximal row, because it is a sesamoid bone and has only one side that can articulate (Virginia 1999). Also contributing to the integrity of the joint is an articular disc that attaches to the distal radius and ulna and articulates with the triquetral and lunate bones. This articular disc with the distal radius forms a concave ellipsoidal articular surface that is mirrored by the convex shape of the proximal row.
The distal row is closely approximated to the metacarpus region of the hand and articulates with the roots of the five metacarpal bones. It includes the hamate (hook-shaped), capitate (head-shaped), trapezium (table-shaped figure with no two parallel sides), and trapezoid (table-shaped structure with two parallel sides). The carpal bones of the distal row are united to each other as a unit via intercarpal ligaments. These bones also form the carpometacarpal (CMC) joint by tightly binding to the metacarpal bones (McCann & Wise 2011).
Metacarpals
The metacarpals are long, narrow bones with knobby ends. They form the palm of the hand, located between the bones of the carpus and the bones of the phalanges. There are five metacarpal bones in the hand, and they are numbered I–V, beginning at the thumb (Virginia 1999).
Each metacarpal bone is characterized as having a proximal base, a shaft, a neck and a distal head. The distal head of each metacarpal articulates with the proximal phalanges of each digit, and forms a metacarpophalangeal joint. Each metacarpal end articulates proximally with one of the distal carpal bones, and these articulations are named carpometacarpal joints (Taylor & Schwarz 1955).
Phalanges
Phalanges are bones of the fingers and the thumb. There are a total of 14 phalanges in each hand. The thumb contains two phalanges: a proximal phalanx (plural: phalanges) and a distal phalanx. Each of the other digits comprises a proximal, a middle and a distal phalanx bone. These bones articulate with each other through the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints. The base of the proximal phalanges articulates with the metacarpal bones via the metacarpophalangeal (MCP) joints (Rhee et al 2006; McCann & Wise 2011).
Ligaments
There are a variety of ligaments in the wrist and hand region that primarily serve as the stabilizers of the joints.
The wrist joints are held together by an array of ligaments such as the palmar and dorsal radiocarpal ligaments, and the ulnar and radial collateral ligaments. These unite the radius and ulna with the carpal bones. The intercarpal articulations between the carpals are strengthened as a unit by a group of ligaments. These include the radiate carpal, pisohamate and intercarpal ligaments (Platzer 2004).
Motion unit | Movement type | Range of motion (°) | Reference |
Functional range of motion in ADL | Flexion | 45 | Brigstocke et al (2013) |
Extension | 50 | ||
Radial deviation | 15 | ||
Ulnar deviation | 40 | ||
Average range of motion in ADL | Flexion | 50 | Nelson et al (1994) |
Extension | 51 | ||
Radial deviation | 12 | ||
Ulnar deviation | 40 |
Table 12.1
Functional and average range of motion of the wrist
The carpometacarpal joints connect the distal row of carpals with the proximal bases of the metacarpals. These joints are supported by some strong ligaments, including the carpometacarpal and pisometacarpal ligaments. Like the intercarpal articulations, the intermetacarpal articulations between the metacarpals are also strengthened by a group of ligaments, such as the dorsal, palmar, and interosseous metacarpal ligaments (Platzer 2004).
The ligaments of the metacarpophalangeal joints unite the metacarpal bones with the proximal phalanges. The radial and ulnar collateral ligaments are the primary stabilizers of the metacarpophalangeal joints (Berger & Weiss 2003). However, specialized ligaments are also found at these joints, such as the deep transverse metacarpal ligament and the natatory ligament. Like the metacarpophalangeal joints, the ligaments of the proximal interphalangeal, distal interphalangeal and the interphalangeal joints are all very similar in configuration (Petre & Deune 2013).
Range of motion
The wrist is capable of three types of movement: flexion and extension, pronation and supination, and radial or ulnar deviation. Palmer et al (1985) suggested that the functional range of the wrist is 5° of flexion, 30° of extension, 10° of radial deviation and 15° of ulnar deviation. In another study, Nelson et al (1994) reported that the average range of motion of the wrist in activities of daily living (ADL) is 50° of flexion, 51° of extension, 12° of radial deviation and 40° of ulnar deviation. Based on the goniometer measurement of wrist movement in 40 subjects, Ryu et al (1991) found an average maximum range of motion of 138° of flexion–extension (78° of flexion to 60° of extension) and 58° of radial–ulnar deviation (21° of radial deviation to 38° of ulnar deviation). See Tables 12.1 for an overview of wrist movement and Table 12.2 for information about the hand.
However, this extensive range of movement comes at a cost and leads to many hand and wrist disorders, most commonly traumatic injuries. On top of that, surgical processes may further complicate these injuries. For any physical therapist or general physician treating hand or wrist problems, detailed knowledge and understanding of hand/wrist anatomy is therefore essential to diagnose conditions accurately and deliver the best quality of care.
Epidemiology
Wrist and hand disorders
Wrist and hand disorders are the most common occupation-related musculoskeletal (MSK) diseases in the UK. The rate of incidence and prevalence of these disorders are also more predominant than any other MSK conditions. In a 3-year Musculoskeletal Occupational Surveillance Scheme (MOSS), Cherry et al (2001) found that upper limb disorders accounted for 66% of an estimated total of 8070 cases, with hand or wrist conditions comprising 44% of the total.
|
|
| Range of motion (°) | |
Motion unit | Joint name | Movement type | ||
Average | Total arc | |||
Normal range of motion (thumb) | Metacarpophalangeal joint | Flexion | 0–56 (in 85% population) | 0–124 |
Interphalangeal joint | Flexion | (-) 5–73 | ||
Normal range of motion (finger) | Metacarpophalangeal joint | Flexion | 0–100 | 0–290 |
Distal interphalangeal joint | Flexion | 0–85 | ||
Proximal interphalangeal joint | Flexion | 0–105 | ||
Functional range of motion (thumb) | Metacarpophalangeal joint | Flexion | 21 | 40 |
Interphalangeal joint | Flexion | 18 | ||
Functional range of motion (finger) | Metacarpophalangeal joint | Flexion | 61 | 164 |
Distal interphalangeal joint | Flexion | 39 | ||
Proximal interphalangeal joint | Flexion | 60 | ||
Table 12.2
Normal and functional range of motion of the hand joints
Data adapted from Hume et al (1990)
Hand and wrist disorders tend to be predominant among adults in the general population and are more prevalent in women than in men. Walker-Bone et al (2004), in a two-stage cross-sectional study of 9696 healthy adults, reported that the prevalence rates of several hand and wrist conditions were higher in female adults than in male (see Table 12.3). Table 12.4 lists some common pathological conditions of the wrist and hand.
| Prevalence in general population (%) | |
Diagnosis | Men (n = 2696) | Women (n = 3342) |
De Quervain syndrome | 0.5 | 1.3 |
Tenosynovitis of the wrist | 1.1 | 2.2 |
Carpal tunnel syndrome | 0.9 | 1.2 |
Specific wrist/hand disorders | 2.6 | 3.6 |
Nonspecific wrist/hand pain | 8.7 | 11.5 |
Osteoarthritis, DIP joint | 1.1 | 2.8 |
Osteoarthritis, thumb base | 2.5 | 4.6 |
Table 12.3
Estimated prevalence of hand/wrist diagnoses in the general population
Data from Walker-Bone et al (2004)
Condition | Description | Reference |
De Quervain syndrome | A tenosynovitis of the sheath that involves abductor pollicis longus and the extensor pollicis brevis Occurs most commonly in the middle-aged Affects women 8–10 times more often than men Symptoms include difficulty gripping, pain and tenderness on certain movements of the wrist, and pain along the base of the thumb | McRae (2010) |
Dupuytren’s disease | Involves nodular thickening and a contracture of the palmar fascia Most commonly affects the ring finger, followed by the middle and little fingers Occurs predominantly in men over the age of 40 Typically affects people with northern European ancestry; rare in people from China, India and Africa May be associated with diabetes, epilepsy, gout or alcoholic cirrhosis | Burge (1999), Mir (2003) |
Carpal tunnel syndrome | A condition in which the median nerve is compressed as it traverses the tunnel under the thick transverse carpal ligament Usually occurs in middle-aged (30–60 years age group), obese women Almost four times more prevalent in older women than in men May be associated with myxedema, acromegaly, pregnancy, obesity, rheumatoid arthritis, primary amyloidosis, tophaceous gout and repetitive work with the hand Symptoms include numbness, tingling, pain and weakness in the palm of the hand and the fingers | Silverstein et al (1987), Atroshi et al (1999) |
Ulnar tunnel syndrome | A condition in which the ulnar nerve is compressed as it passes via the ulnar carpal canal Causes include ganglionic compression, repetitive trauma, ulnar artery disease, inflammatory arthritis and old carpal or metacarpal fractures Symptoms include small muscle wasting and weakness in the hand | Grundberg (1984), McRae (2010) |
Rheumatoid arthritis | Commonest of the arthritides Progressively affects the tendons, joints, muscles, arteries and nerves of the hand and wrist Produces most severe deformities Has crippling effects on hand function Affects women three times more often than men Peak incidence: between 4th and 6th decades | Mir (2003) |
Extensor tenosynovitis | An inflammation of the tendons at the back of the wrist Usually occurs in 20–40 years age group Often caused by a period of overactivity | McRae (2010) |
Wrist bone fracture (scaphoid) | A common bone fracture in the carpus region May involve direct axial compression or hyperextension of the wrist Occurs more often in men than in women Most common in young men (age group: 15–29 years) following a fall, athletic injury, or traumatic injury on an outstretched hand Symptoms include pain in wrist motion, swelling around the wrist, and tenderness in the wrist and at the thumb base | Fisk (1970), Leslie & Dickson (1981) |
Mallet finger | An injury of the extensor digitorum tendon of the fingers Results from interruption of the terminal extensor mechanism at the DIP joint Usually occurs when an object strikes the finger hard and creates a forceful flexion of an extended DIP joint Symptoms include tenderness just behind the nail, pain and swelling at the end of the injured finger, and inability to straighten the tip of that finger | Wang & Johnson (2001), Anderson (2011) |
Tumors in the hand | Involve the soft tissues Common tumors include ganglions, mucous cysts, implantation dermoid cysts, chondroma osteoid osteoma and solitary glomus | McRae (2010) |
