Carpal Bones

The strain index has not been developed to predict increased risk for distal upper-extremity disorders to uncertain etiology or relationship to work. Examples include ganglion cysts, osteoarthritis, avascular necrosis of carpal bones, and ulnar nerve entrapment at the elbow. 

The wrist functions by allowing changes of orientation of the hand relative to the forearm. The wrist joint complex consists of multiple articulations of eight carpal bones with the distal radius, the structures of the ulnocarpal space, the metacarpals, and each other. This collection of bones and soft tissues is capable of a substantial arc of motion that augments hand and finger function. 

Kobayashi M., Berger R.A., Nagy L., et al. 1997. Normal kinematics of carpal bones a three-dimensional analysis of carpal bone motion relative to the radius. /. Biomech. 30 787. 

Joints such as the ankle and wrist consist of many small bones, and their surfaces must be determined accurately. This may be done via cadaveric examination or noninvasive means. The cadaveric system generally consists of the following (or a modification) The ligaments and tendons are stained to display the attachments (insertions) into the bones the construct is then embedded in Plexiglas, and sequential pictures or scans are taken as the construct is either sliced or milled. Slices on the order of a fraction of a millimeter are needed to fully describe the surfaces of wrist carpal bones. Noninvasive measures, such as modem high-sensitivity computed tomographic (CT) scans, may also be able to record geometries at the required level of detail. 

Fig. 5.10. Oblique coronal STIR image of the scaphoid. There is extensive marrow oedema with fluid around the carpal bones, features in keeping with a scaphoid fracture. Radiographs were normal.

The carpal bones may appear irregular and fragmented during normal development if they develop from several ossification centres prior to coalescing into one bone mass. The pisiform is the bone most frequently affected and can be easily mistaken for a post-traumatic bony fragment or even a foreign body within the soft tissues of the palm when viewed in lat-... 

Fractures and dislocations of the carpal bones are rare, and a child with a painful wrist following trauma is much more likely to have injured the distal radius (Fig. 19.33). Carpal bone fractures are uncom-... 

Carpal T mnel An internal passage in the wrist between the extensor retinaculum and the carpal bones through which the median nerve, finger flexor tendons, and blood vessels pass from the arm to the hand. 

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

WRULDs describe a group of illnesses which can affect the neck, shoulders, arms, elbows, wrists, hands and fingers. Tenosynovitis (affecting the tendons), carpal tunnel syndrome (affecting the tendons which pass through the carpal bone in the hand) and frozen shoulder are all examples of WRULDs which differ in the manifestation and site of the illness. The term repetitive strain injury (RSI) is commonly used to describe WRULDs. 

The wrist or carpus is the distal articulation of the radius and the articular disk with the proximal row of carpal bones. The disk joins the ulna and radius and lies between the ulna and the proximal row of carpal bones. Laterally to medially, these bones are the scaphoid (navicular), lunate, and the triquetrum. A small bone, the pisiform, lies slightly anterior to the triquetrum. 

The midcarpal joint, consisting of the combined articulations between the proximal and distal rows of the carpal bones (Fig. 83-2)... 

The carpal bones form an arch spanned by the flexor relimculum. The concavity of the arch lies on the palmar surface between the bones and... 

The hand consists of five metacarpal bones that articulate proximally with four carpal bones in the distal row. The second and third metacarpals remain relatively fixed while the first, fourth, and fifth move around this fixed segment. The five metacarpals articulate distally with the proximal phalanges of the fingers. These are usually considered ginglymus or hinge joints. They permit flexion-extension, abduction, adduction, and circumduction. 

The wrist and hand joints should be palpated for swelling, asymmetries, and tenderness. The skin of the wrist and hand shonld be evalnated for temperature and moisture changes. Tendons or joints may be tender. The anatomic snuffbox should be palpated. In case of trauma, any tenderness in this area should be noted, because the navicular is the most commonly fractured of the carpal bones. 

In carpal tunnel syndrome, the median nerve is compressed in the tunnel by fibrous bands, scar tissue from chronic inflammation or microtrauma, arthritis, or myxedema caused by hypothyroidism. The edema of pregnancy can create a carpal tunnel syndrome. Somatic dysfunction ofthe carpal bones can be a cause of carpal tunnel syndrome. 

Osteopathic treatment is aimed at stretching soft tissues, freeing restricted carpal bones, removing edema fluid, and improving circulation and nerve function. 

A 1-year observational study of 73 asthmatic children, who were newly started on ICS (fluticasone 250 gg/day, gradually decreased to 125 ng/day) in China, did not suggest any delay in the increase of height, weight and bone age of ulna, radius, and short finger bones, compared to reference ranges pi ]. Furthermore, no difference was observed in Body Mass Index (BMI) before and after one year of treatment. However, the carpal bone age was delayed during the treatment period. 

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