Fig. 16. Ulnar styloid impaction. Frontal radiograph of the wrist demonstrates a curved, or ''parrot beak,'' ulnar styloid, with subchondral changes in both the ulnar styloid and the trique-trum (arrows). Soft tissue swelling at the ulnar aspect of the wrist is also seen.
(Fig. 18) [63-69]. Ulnar styloid nonunion is classified as type I or type II. Type I nonunion involves the tip of the ulnar styloid. The TFCC remains intact, and the DRUJ is stable. Type II nonunion involves the base of the ulnar styloid. Hence the TFCC attachment is disrupted, and the DRUJ is unstable . Conventional radiographs demonstrate nonunion of an ulnar styloid fracture and may show subchondral changes in the proximal triquetrum. MRI may show marrow edema, chondromalacia, and ununited bone fragments (Fig. 19). MR arthrography, as mentioned previously, can aid in better evaluation of the ulnar attachments of the TFCC . Treatment depends on the type of nonunion. For a type I nonunion, the bone fragment should be removed. For type II, the ul-nar styloid, along with the TFCC, should be fixed to the distal ulna .
Fig. 18. Ulnar styloid impaction with styloid nonunion. Coronal Tl-weighted (A) and fat-suppressed T2-weighted (B) images demonstrate a type 2 styloid nonunion (asterisk), with subchondral change in the ulnar aspect of the triquetrum (black arrowhead), subchondral change and marrow edema in the distal ulna and in the styloid fragment (white arrowheads), and surrounding soft tissue edema.
The normal lunate has one distal articular facet, where it articulates with the capitate. Approximately 44% to 73% of the population has a second facet at the ulnar side of the lunate, which articulates with the proximal pole of the hamate (Fig. 20) . This type of lunate has been called a type II lunate [70-72]. In a study of cadaveric wrists, Viegas and colleagues  found that the
incidence of arthrosis at the proximal pole of the hamate was 38.2% in the cadaver population with a type II lunate, compared with 1.8% in those with a type I lunate. In the same study, the authors found that the proximal pole of the hamate is one of the most frequent sites of cartilage damage in the wrist. This finding is most likely due to the disruption of the second carpal arc that occurs in patients with a type II lunate . During forced ulnar deviation, the hamate ''jumps'' over this disruption, leading to increased load on the proximal pole of the hamate . Many of these lesions are clinically silent, and correlation must be made with a patient's symptoms. A type II lunate may be seen on conventional radiographs with a reported accuracy of 64% to 72% . MRI and MR arthrography with a midcarpal joint injection may show chondromalacia of the proximal pole of the hamate, subchondral changes, and marrow edema [38,75].
Ulnar impingement syndrome is a condition that develops when a short ulna impinges on the distal radius proximal to the sigmoid notch [76,77]. The short ulna may be congenital, due to premature fusion of growth plates, or a result of prior surgery (eg, Darrach ulnar shortening surgery, Madelung corrective surgery, surgery for rheumatoid arthritis) [55,76]. The short ulna impinges on the distal radius, forming a painful pseudarthrosis, which is aggravated by pronation and supination (Fig. 21) . Conventional radiographs demonstrate a short ulna abutting the distal radius, with scalloping of the cortex of the distal radius proximal to the sigmoid notch . MRI can aid in earlier diagnosis, with detection of marrow edema and subcortical marrow changes.
Guyon's canal is a fascial tunnel that is bounded dorsally by the pisohamate ligament, volarly by forearm fascia and expansions from the flexor carpi ulnaris, medially by the pisiform, and laterally by the hook of the hamate. The canal extends approximately 4 cm from the proximal aspect of the pisiform to the level of the hamate. The ulnar nerve, ulnar artery, and (in some patients) veins pass through Guyon's canal . Any mass in this region could cause compression of the deep motor branch of the ulnar nerve. Masses that have been described in this region include ganglia, anomalous muscles, lipomas, and ulnar artery aneurysms .
Along with clinical history and physical examination, imaging is vital to narrowing down the differential diagnosis in ulnar-sided wrist pain. Treatments vary widely, depending on the cause of the pain, and differentiating the various entities is crucial. Conventional radiographs, conventional arthrography, CT, MRI, and MR arthrography are all useful modalities that are often used in concert to help guide diagnosis and treatment.
The author would like to thank D. Laurie Persson for his excellent original illustrations used in this review.
 Palmer AK. The distal radioulnar joint. Orthop Clin North Am 1984;15:321.
 Steinbach LS, Palmer WE, Schweitzer ME. Special focus session. MR arthrography. Radiographics 2002;22(5):1223-46.
 Cerezal L, Abascal F, Garcia-Valtuille R, et al. Wrist MR arthrography: how, why, when. Radiol Clin North Am 2005;43(4):709-31.
 Palmer AK. Triangular fibrocartilage complex lesion: a classification. J Hand Surg [Am] 1989;14(4):594-606.
 Palmer AK, Werner FW. The triangular fibrocartilage complex of the wrist: anatomy and function. J Hand Surg [Am] 1981;6(2):153-62.
 Chidgey LK. The distal radioulnar joint: problems and solutions. J Am Acad Orthop Surg 1995;3:95-109.
 Thiru-Pathi RG, Ferlic DC, Clayton ML, et al. Arterial anatomy of the triangular fibrocartilage of the wrist and its surgical significance. J Hand Surg [Am] 1986;11 (2):258-63.
 Deitch MA, Stern PJ. Ulnocarpal abutment: treatment options. Hand Clin 1998;14(2): 251-63.
 Nagle DJ. Arthroscopic treatment of degenerative tears of the triangular fibrocartilage. Hand Clin 1994;10(4):615-24.
 Mikic ZD. Age changes in the triangular fibrocartilage of the wrist joint. J Anat 1978;126(2):367-84.
 ViegasSF, Patterson RM, HokansonJA, etal. Wristanatomy: incidence, distribution, and correlation of anatomic variations, tears and arthrosis. J Hand Surg [Am] 1993;1 8(3):463-75.
 Harrison MO, Freiberger RH, Ranawat CS. Arthrography of the rheumatoid wrist joint. AJR Am J Roentgenol 1971;112(3):480-6.
 Kessler I, Silberman Z. Experiment study of the radiocarpal joint by arthrography. Surg Gynecol Obstet 1961;112:33-40.
 Kang HS, Kindynis P, Brahme SK, et al. Triangular fibrocartilage and intercarpal ligaments of the wrist: MR imaging-cadaveric study with gross pathologic histologic correlation. Radiology 1991;181(2):401-4.
 Steinbach LS, Smith DK. MRI of the wrist. Journal of Clinical Imaging 2000;24(5):298-322.
 Zlatkin MB, Chao PC, Osterman AL, et al. Chronic wrist pain: evaluation with highresolution MR imaging. Radiology 1989;173(3):723-9.
 Golimbu CN, Firooznia H, Melone CP, et al. Tears of the triangular fibrocartilage of the wrist: MR imaging. Radiology 1989;173(3):731-3.
 Schweitzer ME, Brahme SK, HodlerJ, et al. Chronic wrist pain: spin-echo and short tau inversion recovery MR imaging and conventional MR arthrography. Radiology 1992;182(1): 205-11.
 Potter HG, Asnis-Ernberg L, Weiland AJ, et al. The utility of high-resolution magnetic resonance imaging in the evaluation of the triangular fibrocartilage complex of the wrist. J Bone Joint Surg Am 1997;79(11):1675-84.
 Oneson SR, Timins ME, Scales LM, et al. MR imaging diagnosis of triangular fibrocartilage pathology with arthroscopic correlation. AJR Am J Roentgenol 1997;168(6):1513-8.
 Haims AH, Schweitzer ME, Morrison WB, etal. Limitations of MR imaging in the diagnosis of peripheral tears of the triangular fibrocartilage of the wrist. AJR Am J Roentgenol 2002;178(2):419-22.
 Schmitt R, ChristopoulosG, Meier R, etal. Direct MR arthrography of the wrist in comparison with arthroscopy: a prospective study on 125 patients. Rofo 2003;175(7):911-9.
 Shin AY, Battaglia MJ, Bishop AT. Lunotriquetral instability: diagnosis and treatment. J Am Acad Orthop Surg 2000;8(3):170-9.
 Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg [Am] 1996;21(2):170-8.
 Ritt MJ, Bishop AT, Berger RA, et al. Lunotriquetral ligament properties: a comparison of three anatomic subregions. J Hand Surg [Am] 1998;23(3):425-31.
 Buterbaugh GA, Brown TR, Horn PC. Ulnar-sided wrist pain in athletes. Clin Sports Med 1998;17(3):567-83.
 Reagan DS, Linschied RL, DobynsJH. Lunotriquetral sprains. J Hand Surg [Am] 1984;9(4): 502-14.
 Ambrose L, Posner MA. Lunate-triquetral and midcarpal joint instabilities. Hand Clin 1992;8(4):653-68.
 Kleinman WB, Graham TJ. Distal ulnar injury and dysfunction. In: Peimer CA, editor. Surgery of the hand and upper extremity. New York: McGraw-Hill; 1996. p. 667-710.
 Viegas SF, Patterson RM, Peterson PD, etal. Ulnar-sided perilunate instability: an anatomic and biomechanic study. J Hand Surg [Am] 1990;15(2):268-78.
 Viegas SF. Ulnar-sided wrist pain and instability. AAOS Instructional Course Lectures 1998;47:215-8.
 Weiss LE, Taras JS, Sweet S, et al. Lunotriquetral injuries in the athlete. Hand Clin 2000;16(3):433-8.
 Milch H. Cuff resection of the ulna for malunited Colles' fracture. J Bone Joint Surg 1941;23: 311-3.
 Darrow JC, Linscheid RL, Dobyns JH, et al. Distal ulnar recession for disorders of the distal radioulnar joint. J Hand Surg [Am] 1985;10(4):482-91.
 Kovanlikaya I, Camil D, Cakmakci H, et al. Diagnostic value of MR arthrography in detection of intrinsic carpal ligament lesion: use of cine-MR arthrography as a new approach. Eur Radiol 1997;7(9):1441-5.
 Zlatkin MB, RosnerJ. MR imaging of ligaments and triangular fibrocartilage complex of the wrist. Magn Reson Imaging Clin N Am 2004;12(2):301-31.
 Smith DK. MR imaging of normal and injured wrist ligaments. Magn Reson Imaging Clin N Am 1995;3(2):229-48.
 Cerezal L, del Pina F, Abascal F. MR imaging findings in ulnar-sided wrist impaction syndromes. Magn Reson Imaging Clin N Am 2004;12(2):281-99.
 Braun H, Kenn W, Schneider S, etal. Direct MR arthrography of the wrist: value in detecting complete and partial defects of intrinsic ligaments and the TFCC in comparison with arthroscopy. Rofo 2003;175(11):1515-24.
 Ekenstam F, Hagert CG. Anatomical studies of the geometry and stability of the distal radioulnar joint. Scand J Plast Reconstr Surg 1985;19(1):17-25.
 Ray RD, Johnson RJ, Jameson RM. Rotation of the forearm—an experimental study of pronation and supination. J Bone Joint Surg 1951;33A(4):993-6.
 Ekenstam F. Osseous anatomy and articular relationships about the distal ulna. Hand Clin 1998;14(2):161-4.
 Loftus JB, Palmer AK. Disorders of the distal radioulnar joint and triangular fibrocartilage complex: an overview. In: Lichtman DM, Alexander AH, editors. The wrist and its disorders. Philadelphia: WB Saunders; 1997. p. 385-414.
 Chiang CC, Chang MC, Lin CFJ, et al. Computerized Tomography in the diagnosis of subluxation of the distal radioulnar joint. Chin Med J (Engl) 1998;61(12):708-15.
 Mino DE, Palmer AK, Levinsohn EM. The role of radiography and computerized tomography in the diagnosis of subluxation and dislocation of the distal radioulnar joint. J Hand Surg [Am] 1983;8(1):23-31.
 Wechsler RJ, Wehbe MA, Rifkin MD, et al. Computed tomography diagnosis of the distal radioulnar subluxation. Skeletal Radiol 1987;16(1):1-5.
 Taleisnik J. Pain on the ulnar side of the wrist. Hand Clin 1987;3(1 ):51-68.
 Hajj AA, Wood MB. Stenosing tenosynovitis of the extensor carpi ulnaris. J Hand Surg [Am] 1986;11(4):519-20.
 Harris HA. The pisiform bone. Nature 1944;153:715.
 Williams PL, Warwick R. The carpus. In: Pick TP, Howden R, editors. Gray's anatomy. 36th edition. Edinburgh (Scotland): Churchill Livingstone; 1980. p. 162-3.
 Weston WJ, Kelsey CK. Functional anatomy of the pisicuneiform joint. Br J Radiol 1973;46(549):692-4.
 Paley D, McMurtry RY, Cruickshank B. Pathologic conditions of the pisiform and pisotrique-tral joint. J Hand Surg [Am] 1987;12(1):110-9.
 Coyle MP Jr, Carroll RE. Dysfunction of the pisotriquetral joint: treatment by excision of the pisiform. J Hand Surg [Am] 1985;10(5):703-7.
 Friedman SL, Palmer AK. The ulnar impaction syndrome. Hand Clin 1991;7(2):295-310.
 Hodge JC, Yin Y, Gilula LA. Miscellaneous conditions of the wrist. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: Saunders; 1996. p. 523-46.
 Escobedo EM, Bergman AG, Hunter JC. MR imaging of ulnar impaction. Skeletal Radiol 1995;24(2):85-90.
 ImaedaT, Nakamura R, Shionoya K, etal. Ulnar impaction syndrome: MR imaging findings. Radiology 1996;201(2):495-500.
 Cerezal L, del Pinal F, Abascal F, et al. Imaging findings in ulnar-sided wrist impaction syndromes. Radiographics 2002;22(1):105-21.
 Palmer AK, Werner FW. Biomechanics of the distal radioulnar joint. Clin Orthop 1984;187:26-35.
 Palmer AK, Glisson RR, Werner FW. Relationship between ulnar variance and triangular fibrocartilage complex thickness. J Hand Surg [Am] 1984;9(5):681-3.
 Topper SM, Wood MB, Ruby LK. Ulnar styloid impaction syndrome. J Hand Surg [Am] 1997;22(4):699-704.
 Garcia-Elias M. Soft-tissue anatomy and relationships about the distal ulnar. Hand Clin 1998;14:165-76.
 Burgess RC, Watson HK. Hypertrophic ulnar styloid nonunions. Clin Orthop 1988;228: 215-7.
 Cheng SL, Axelrod TS. Management of complex dislocations of the distal radioulnar joint. Clin Orthop 1997;341:183-91.
 Lindau T, Adlercreutz C, Aspenberg P. Peripheral tears of the triangular fibrocartilage complex cause distal radioulnar joint instability after distal radial fractures. J Hand Surg [Am] 2000;25(3):464-8.
 Lindau T, Hagberg L, Adlercreutz C, etal. Distal radioulnar joint instability is an independent worsening factor in distal radial fractures. Clin Orthop 2000;376:229-35.
 Melone CP Jr, Nathan R. Traumatic disruption of the triangular fibrocartilage complex: path-oanatomy. Clin Orthop 1992;275:65-73.
 Palmer AK. Triangular fibrocartilage disorders: injury patterns and treatment. Arthroscopy 1990;6(2):125-32.
 Reeves B. Excision of the ulnar styloid fragment after Colles' fracture. IntSurg 1966;45(1): 46-52.
 Burgess RC. Anatomic variations of the midcarpal joint. J Hand Surg [Am] 1990;15(1): 129-31.
 Viegas SF, Wagner K, Patterson R, et al. Medial (hamate) facet of the lunate. J Hand Surg [Am] 1990;15(4):564-71.
 Viegas SF. The lunatohamate articulation of the midcarpal joint. Arthroscopy 1990;6(1): 5-10.
 Peh WC, Gilula LA. Normal disruption of carpal arcs. J Hand Surg [Am] 1996;21(4): 561-6.
 Sagerman SD, Hauck RM, Palmer AK. Lunate morphology: can it be predicted with routine x-ray films? J Hand Surg [Am] 1995;20(1):38-41.
 Pfirrmann CW, Theumann NH, Chung CB, et al. The hamatolunate facet: characterization and association with cartilage lesions: magnetic resonance arthrography and anatomic correlation in cadaveric wrists. Skeletal Radiol 2002;31(8):451-6.
 Bell MJ, Hill RJ, McMurtry RY. Ulnar impingement syndrome. J Bone Joint Surg Br 1985;67(1):126-9.
 McKee MD, Richards RR. Dynamic radio-ulnar convergence after the Darrach procedure. J Bone Joint Surg Br 1996;78(3):413-8.
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