Ulnar-sided wrist pain. Part I: anatomy and physical examination
- First Online:
- 3.8k Downloads
Ulnar-sided wrist pain is a common complaint, and it presents a diagnostic challenge for hand surgeons and radiologists. The complex anatomy of this region, combined with the small size of structures and subtle imaging findings, compound this problem. A thorough understanding of ulnar-sided wrist anatomy and a systematic clinical examination of this region are essential in arriving at an accurate diagnosis. In part I of this review, ulnar-sided wrist anatomy and clinical examination are discussed for a more comprehensive understanding of ulnar-sided wrist pain.
KeywordsWrist Anatomy Clinical examination Magnetic resonance imaging (MRI)
Pain at the ulnar aspect of the wrist is a diagnostic challenge for hand surgeons and radiologists, due to the small and complex anatomic structures involved. Imaging evidence of the underlying cause of pain is frequently subtle, involving small structures. Familiarity with clinical findings and pertinent anatomy would considerably aid in making accurate diagnoses. In part I of this review, ulnar-sided wrist anatomy and clinical examination are reviewed.
Bones and joints
At the ulnar aspect of the wrist, the distal ulna articulates with the triangular fibrocartilage complex (TFCC). There are two eminences at the distal ulna: the head and the styloid process. Laterally, the head of the ulna is a large round articular eminence with a distally oriented oval articular surface and a horizontal orientation that articulates with the radius. This articulation moves anteriorly and posteriorly due to motion at the distal radioulnar joint during pronation and supination. The styloid process arises from the medial and posterior aspect of the distal ulna, is non-articular in nature, and is the point of origin of the ulnar collateral ligament. The styloid process is separated from the head by a shallow depression where the triangular fibrocartilage attaches.
Ulnar variance refers to the lengths of the distal articular surfaces of the radius and ulna . This variance affects the force distribution across the wrist and is related to some ulnar pathologies. Several studies have reported an association of negative ulnar variance with Kienböck’s disease [3, 4, 5]. Bonzar et al. confirmed such an association after correcting for the influence of age on the measurement of ulnar variance . However, D’Hoore and colleagues reported that negative ulnar variance does not seem to be an important factor in the etiology of Kienböck’s disease . Nakamura et al. found no significant difference in ulnar variance between Japanese subjects with normal wrists and those affected by Kienböck’s disease . The relationship between Kienböck’s disease and negative ulnar variance remains controversial. On the other hand, positive ulnar variance plays a significant role in TFCC tears and ulnar impaction syndrome [2, 8, 9, 10, 11]. Chronic impaction between the ulnar head and the TFCC and ulnar carpus results in the ulnar impaction syndrome, where degenerative tearing of the TFCC and chondromalacia of the lunate, triquetrum, and distal ulnar head are seen .
The triquetrum articulates with the hamate at its distal aspect, with the lunate at the lateral aspect, and with the pisiform at its volar aspect. The triquetrum also articulates with the triangular fibrocartilage at its proximal aspect. The triquetrohamate joint is a helical joint, which permits the triquetrum to rotate around the hamate and also has a limited amount of translation distally, in the fashion of a screw. Most triquetrohamate joints lie on a continuous plane with the capitolunate joint and are described as type 1; in 20% of patients the triquetrohamate joint is separated from the capitolunate joint by a hamatolunate facet, described as a type 2 lunate .
The pisiform articulates with the triquetrum at its posterior surface and provides attachments to the flexor carpi ulnaris, abductor digiti quinti, and the transverse carpal ligament. The pisotriquetrum is a synovial joint that lies anterior to the remainder of the carpus and is susceptible to diseases that affect synovial joints. The synovium of the pisotriquetral joint does not communicate with the radiocarpal compartment at arthrography 12–25% of the time [17, 18]. The pisiform and pisotriquetral joint are best evaluated via the ‘ball catcher’ or ‘allstate’ views.
The distal radioulnar joint (DRUJ) is a pivot joint which permits rotation of the distal radius about the ulna during forearm pronation and supination. From pronation to supination, the ulnar head rotates approximately 150° counterclockwise in relation to the radius. The DRUJ is stabilized by the volar radioulnar ligament, the dorsal radioulnar ligament, and the TFCC. The volar and dorsal radioulnar ligaments are narrow bands of fibers which extend, respectively, from the anterior and posterior margins of the ulnar notch of the radius to the ulna. There is an isolated synovial lining about the DRUJ which extends proximally between the radius and ulna . On true lateral radiographs, the distal radius and ulna should be overlapping. If the radius and ulna are not superimposed while the carpal bones are seen to overlap, the suggestion is of a DRUJ injury.
The lunotriquetral ligament (LTL) is U-shaped on sagittal section and has three separate zones: dorsal, proximal, and volar. The dorsal and volar zones are ligamentous. The former is highly important functionally as a restraint to rotation, while the latter is the strongest and thickest of all three zones and transmits the extension movement of the triquetrum [20, 21]. The proximal zone is fibrocartilaginous and thin . The radiographic appearance of wrists with LTL tears is often normal. Lunotriquetral dissociation will result in disruption of the smooth arcs that are formed by the proximal and distal joint surfaces of the proximal carpal row (Gilula’s arcs I and II) and the proximal joint surfaces of the distal carpal row (Gilula’s arc III). Arthrography can be helpful in demonstrating leakage or pooling of the contrast medium at the lunotriquetral interspace. However, age-related perforations of the LTL proximal zone, other communications between the radiocarpal and midcarpal joints, and asymptomatic LTL tears on arthrography of the normal wrist have been reported.
Triangular fibrocartilage complex
The TFCC is a fibrocartilage–ligament complex which stabilizes the DRUJ, transmits axial load between the carpus and the ulna, and stabilizes the ulnar aspect of the carpus. The TFCC is composed of the disc proper (articular disc), meniscus homologue, ulnolunate ligament, ulnotriquetral ligament, proximal ligamentous component, volar and dorsal radioulnar ligaments, and the ulnar collateral ligament. Because these structures are located in small areas, high-resolution imaging is, we believe, essential to diagnose TFCC injuries.
Nerve and artery
The clinical examination of a patient who presents for evaluation of ulnar-sided wrist pain begins with a thorough history. Hand dominance should be noted. A detailed past medical history that includes previous injury to the affected wrist, as well as other musculoskeletal involvement in the same extremity or in other regions of the body, may give important information that helps the clinician to arrive at an accurate diagnosis. Previous surgical procedures should be noted. The patient’s social history may significantly influence the etiology, treatment, and prognosis. The social history should focus on profession and avocations. It is important to inquire about repetitive movements that the patient may make in work or hobbies, as certain movements may be the source of the pathology or may contribute to ongoing symptoms . Worker’s compensation status may affect outcome and expected postoperative rehabilitation .
The history of present illness must encompass several elements. The clinician should inquire about a history of traumatic injury. The time course of the symptoms should focus on sudden versus gradual onset as well as an acute versus chronic history. A detailed account of the mechanism of injury will give important diagnostic clues into the underlying pathology. For example, DRUJ and TFCC injuries often occur when the wrist is subjected to hyperpronation and axial loading forces . The quality and intensity of pain may also suggest specific etiologies. Any associated numbness or paresthesias must be noted. Exacerbating and alleviating factors as well as radiation of pain is part of a complete history of present illness. The presence or absence of swelling, erythema, and tenderness may also assist in focusing the clinician’s diagnostic evaluation. The onset of deformity must be inquired. For example, a wrist deformity that spontaneously resolved may suggest DRUJ instability . Previous treatments and the response to these treatments, including occupational therapy and injections, provide valuable diagnostic information.
The physical examination of a patient with ulnar-sided wrist pain begins with inspection. Symmetry of the wrist compared with that of the contralateral extremity and symmetry of the ulnar-sided digits compared with that of the radial-sided digits should be noted. Erythema, cyanosis, and edema may be present and should be noted. A focal area of edema around the wrist may suggest a ganglion. Previous surgical or traumatic scars are important to note. Atrophy can be assessed by comparison with the contralateral extremity, and its presence is suggestive of nerve pathology. Atrophy of the hypothenar eminence may result from ulnar nerve compression in Guyon’s canal or more proximally and can be expected to cause sensory disturbances in the ulnar nerve distribution .
Range of motion
Determination of range of motion is the next step in the physical examination. Both active and passive ranges of motion should be determined and compared with those of the contralateral side. Wrist flexion and extension from neutral are tested first. The clinician may expect normal wrist flexion of 80° from neutral and wrist extension of 70° from neutral . Forearm supination and pronation should then be assessed with the patient’s elbow flexed to 90°. Normal pronation of 90° and supination of 90° can be expected . Range of motion of the digits should also be examined. The clinician should expect approximately 90° of flexion and 30° of extension at the metacarpophalangeal joints. The proximal interphalangeal joints are able to be ranged from 0° to 100°, and the distal interphalangeal joints have a normal range of motion from 20° of extension to 90° of flexion . Range of motion of the elbow should be examined, with normal flexion to 135° and normal extension to 0°. Shoulder and neck motion should be measured if deemed necessary based on the clinician’s judgment.
Vascular examination should begin with palpation of the radial and ulnar artery pulses. The ulnar artery is contained within Guyon’s canal, which is a fibro-osseus canal bordered by the pisiform ulnarly and the hook of hamate radially . The clinician may palpate Guyon’s canal volarly to examine the ulnar nerve and artery. Particular attention should be paid to the presence of a ganglion, soft-tissue mass, or aneurysm. Inability to palpate an ulnar pulse may indicate ulnar artery thrombosis that can result from trauma to the hypothenar eminence . An Allen test should be performed to examine the patency of the ulnar and radial arteries. For this test, the patient opens and closes the fist vigorously several times in order to exsanguinate blood from the hand. With the patient’s hand tightly closed in a fist, the examiner occludes both arteries simultaneously by compressing the arteries against the underlying bones. The patient is instructed to open his or her hand. The examiner then releases pressure from either the ulnar or radial artery and observes blood flow into the pale hand. Capillary refill of the palm and digits should be brisk after pressure has been released. This maneuver is then repeated to assess patency of the other artery . Capillary refill of the digits should also be examined. Normal capillary refill takes fewer than 5 s .
Within the distal carpal row, the capitate is palpable immediately proximal to the base of the middle finger metacarpal. When the wrist is in the neutral position, a small depression is palpable in the region of the capitate, and flexion of the wrist causes this depression to roll distally . Located ulnar to the capitate is the hamate. The body of the hamate can be palpated dorsally, while the hook of hamate can be examined with volar palpation. The hook of hamate is located by palpation from the pisiform towards the head of the second metacarpal . This structure is located along a line drawn between these two structures approximately 2 cm from the pisiform. To complete palpation of the osseous structures, the clinician should examine the base of the ring finger and small finger metacarpals.
There are a number of specialized physical examination maneuvers that may aid the diagnosis of ulnar-sided wrist pain. The ulnocarpal stress test, as described by Nakamura et al., is performed by the examiner’s placing the wrist in maximum ulnar deviation while applying an axial load and passively pronating and supinating the wrist [51, 52]. Pain elicited by this maneuver may be indicative of ulnar-sided wrist pain; for example, pain secondary to ulnocarpal impaction syndrome for which the test was originally described . Although a sensitive test for ulnar-sided wrist pain, the ulnocarpal stress test is not specific for ulnocarpal impaction syndrome. Lunotriquetral ligament injury, triangular fibrocartilage tears, and ulnocarpal arthritis will produce positive findings in the ulnocarpal stress test; thus, this test may best be used as a screening tool for intra-articular pathology [52, 53].
The ulnar fovea sign is elicited by palpation of the ‘soft spot’ bordered by the ulnar styloid process dorsally, the flexor carpi ulnaris tendon volarly, the volar surface of the ulnar head proximally, and the pisiform distally . Significant tenderness that reproduces the patient’s complaint in terms of character and location is considered a positive finding of the ulnar fovea sign. This sign is a sensitive test for foveal disruptions and ulnotriquetral ligament injuries .
Midcarpal instability can be investigated with the midcarpal shift test. The patient’s forearm is stabilized in a pronated position in 15° of ulnar deviation. With the examiner’s thumb placed at the distal aspect of the patient’s capitate, volar pressure is applied to the capitate while an axial load is applied to the metacarpals. A painful clunk that reproduces the patient’s symptoms is considered to be a positive finding for the midcarpal shift test .
The pisotriquetral grind test is useful in examining the pisotriquetral joint. To perform this maneuver the examiner moves the pisiform in an ulnar and radial direction, using the thumb and index finger along with compression of the pisiform. Pain elicited by this maneuver is considered to be a positive result of the test and suggests pisotriquetral arthritis [58, 59].
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.