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Dorsoradial Avulsion of the Triangular Fibrocartilage Complex with an Avulsion Fracture of the Sigmoid Notch of the RadiusFrom the Department of Orthopaedic Surgery, School of Medicine, Keio University, Japan and the Department of Orthopaedic Surgery, Ogikubo Hospital, Tokyo, Japan Correspondence: Toshiyasu Nakamura, MD, PhD, Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjukuku, Tokyo 160 8582, Japan. Tel.: +81 3 3353 1211; fax: +81 3 3353 6597. E-mail:tosiyasu{at}sc.itc.keio.ac.jp
We report two extremely rare cases of dorsal radial avulsion injury of the triangular fibrocartilage complex accompanied by an avulsion fracture of the sigmoid notch of the radius. Anatomical reduction of the bone fragment in conjunction with reattachment of the dorsal portion of the radioulnar ligament to the radial sigmoid notch were necessary to restore stability of the distal radioulnar joint and tension of the triangular fibrocartilage proper.
Key Words: radial avulsion • triangular fibrocartilage complex • avulsion fracture • sigmoid notch of the radius • DRUJ instability Palmer (1989) classified radial tears of the triangular fibrocartilage complex (TFCC), in which the radial portion of the triangular fibrocartilage (TFC) proper, the fibrocartilaginous area, is torn, as a ‘Palmer 1D’ tear. Radial tear of the TFCC is usually found as a small slit tear on radiocarpal arthroscopy. It may not destabilise the distal radioulnar joint (DRUJ), despite biomechanical studies indicating that total radial avulsion of the TFCC induced DRUJ instability (Kihara et al., 1995; Martineau et al., 2005). In contrast, ulnar avulsion tear has been widely identified as a potential destabiliser of the DRUJ (Haugstvedt et al. 2006; Nakamura and Yabe, 2000; Nakamura et al., 1996, 2001). In this case report, we report two cases of extremely rare radial avulsion tear of the TFCC associated with an avulsion fracture of the dorsal edge of the radial sigmoid notch. Both wrists demonstrated instability of the DRUJ.
Case 1 A 49 year-old female office worker injured her right wrist when she collided with a metal post while riding in a motorboat. The wrist was forced into hyperpronation and hyperflexion. She visited the local hospital soon after the injury and a small bone fragment in the distal area of the DRUJ was identified on plain X-ray. Her wrist was immobilised for 2 weeks, then active ROM exercises began. As ulnar side wrist pain persisted, she visited our hospital 4 weeks after the accident. She suffered from wrist pain, especially on wringing out towels, twisting doorknobs or doing pushing ups. Her right wrist appeared almost normal, but with a markedly tender area on the dorso-distal side of the DRUJ. She felt pain on maximum pronation and maximum supination and ulnar deviation of the wrist enhanced the pain. The range of motion of the wrist and forearm were not restricted. There was obvious DRUJ instability. The grip strength of the right and left hands was 6 and 23 kg, respectively, because of severe wrist pain. Posteroanterior plain X-ray showed neutral ulnar variance and a small bone fragment at the most dorsal edge of the radial sigmoid notch of the DRUJ (Fig 1). Computed tomography confirmed a small bony fragment at the sigmoid notch and coronal MRI delineated the avulsed fragment at the dorsal sigmoid notch (Fig 2) and a degenerative tear of the TFCC. The patient was treated conservatively with splinting for three months, because she refused surgery. She continued to complain of pain and a loose feeling of the DRUJ, so finally agreed to surgery. Arthroscopy revealed no slit tear in the TFCC. However, loss of the trampoline effect and decrease of tension of the TFC was apparent. Surgical exposure revealed that the bony fragment, attached to the dorsal portion of the radioulnar ligament, had been avulsed from the radial sigmoid notch of the radius, while the palmar side of the TFCC was attached firmly to the palmar side of the sigmoid notch of the radius. The radioulnar ligament, including the bony fragment, was reduced and reattached using a bone anchor (Fig 3). After repair of the avulsion fragment with the radio-ulnar ligament, the tension of the TFC felt almost normal on radiocarpal arthroscopy. The patient no longer had DRUJ instability or wrist pain 2 years after surgery, although the bone fragment was not united on multidirectional plain X-ray.
Case 2 A 20 year-old man fell on his outstretched left hand, forcing hyperextension of the wrist, while skiing. As the ulnar side pain in his wrist persisted, he visited our hospital four weeks after the initial injury. He noted extremely severe wrist pain when doing pushing-ups. On physical examination, his left wrist appeared normal with the exception of a tender spot on the dorsal side of the DRUJ. Although the range of motion was not restricted, he felt pain on forced extension. There was obvious DRUJ instability when compared with the right wrist. The grip strength of the left and right hands was almost identical (44.5/45.5 kg, respectively). Posteroanterior plain X-rays indicated neutral ulnar variance. Computed tomography demonstrated a small bone fragment on the dorsal side of the DRUJ (Fig 4). Arthrogram revealed a leak from the radiocarpal joint to the DRUJ at the radial attachment of the TFCC, suggesting a Palmer 1D TFCC injury (Palmer, 1989). After 5 weeks of conservative treatment without recovery, surgery was carried out. Surgical exploration revealed that the dorsal rim portion of the radioulnar ligament of the TFCC was found to be attached to a detached small bone fragment of the radius. The remainder of the TFCC was still attached to the radius. The bone fragment, including the dorsal portion of the radioulnar ligament, which had been avulsed from the radial sigmoid notch of the radius, was reattached to the original site using a soft wire (Fig 5). Although the bony fragment remained un-united on plain X-ray, the patient no longer had wrist pain or DRUJ instability 2 years after surgery.
The TFCC is important to the stability of the ulnocarpal and distal radioulnar joints. It distributes load between the ulna and ulnar carpus and allows smooth wrist motion and forearm rotation (Nakamura et al., 1996; Palmer and Werner, 1981). TFCC tears induce dysfunction of the wrist, including DRUJ instability. Palmer (1989) classified TFCC injury into two classes, traumatic (Class 1) and degenerative (Class 2). He also subdivided traumatic tears by their site of injury, indicating a central slit as 1A, ulnar tear as 1B, distal tear as 1C and radial slit as 1D and degenerative tears according to development, in which degeneration of the TFC was classified as 2A, degeneration of the TFC with rupture of the lunotriquetral ligament as 2B, perforation of the TFC as 2C, perforation of the TFC with rupture of the lunotriquetral ligament as 2D and further massive degenerative tear as 2E. According to this classification system, class 1D represents a radial avulsion injury of the TFC, in which avulsion fracture of the sigmoid notch of the radius can be, theoretically, included as well (Palmer, 1989) (Fig 6). However, TFCC injury with avulsion fracture of the radial sigmoid notch had not been reported previously.
Both of our patients demonstrated avulsion type fractures at the most dorsal edge of the sigmoid notch of the radius (Fig 7). In both patients, the wrist was forcibly pronated, which may have been the cause of the injury. When the radioulnar ligament was stretched from the dorsal side of the radial sigmoid notch by a flexion, extension or over-rotational force, a small fragment of the radial sigmoid notch may have been avulsed from its dorsal edge, while the remainder of the palmar half of the TFCC remained attached to the radius in these patients. Joint congruity of the dorsal sigmoid notch still remained, despite the avulsion fracture of the sigmoid notch, unlike in the recent report of a depressed fracture of the dorsal sigmoid notch of the radius (Thomas et al., 2006).
Detection of the clinical signs and of the small avulsion fracture on plain X-ray may easily be missed and computed tomography may be useful to delineate such a small fragment and to indicate the precise fracture site. MRI may be of advantage to demonstrate damaged soft tissues around the avulsed fragment. In case 1, arthroscopic repair was not possible, because radiocarpal arthroscopy could not visualise the avulsed fragment or radial tear site of the TFCC. Open reduction and fixation of the avulsed fragment with the radioulnar ligament was successful in restabilising the DRUJ in both cases. Despite the bony non-union in both cases, stability of the DRUJ was obtained because radioulnar ligament tension was recovered. When an avulsed fragment from the radial sigmoid notch is associated with DRUJ instability, reattachment of the radioulnar ligament, including the avulsed fragment, should be considered.
Manuscript received September 20, 2006. Accepted for publication June 14, 2007.
Haugstvedt JR, Berger RA, Nakamura T et al (2006). Relative contributions of the ulnar attachments of the triangular fibrocartilage complex to the dynamic stability of the distal radioulnar joint. Journal of Hand Surgery, 31A: 445–451.[CrossRef][Medline] [Order article via Infotrieve]Kihara H, Short WH, Werner FW et al (1995). The stabilizing mechanism of the distal radioulnar joint during pronation and supination. Journal of Hand Surgery, 20A: 930–936.[CrossRef][Medline] [Order article via Infotrieve]Martineau PA, Bergeron S, Beckman L et al (2005). Reconstructive procedure for unstable radial-sided triangular fibrocartilage complex avulsions. Journal of Hand Surgery, 30A: 727–732.[CrossRef][Medline] [Order article via Infotrieve]Nakamura T, Yabe Y (2000). Histological anatomy of the triangular fibrocartilage complex of the human wrist. Annals of Anatomy, 182: 567–572.[Medline] [Order article via Infotrieve]Nakamura T, Yabe Y, Horiuchi Y (1996). Functional anatomy of the triangular fibrocartilage complex. Journal of Hand Surgery, 21B: 581–586.Nakamura T, Yabe Y, Horiuchi Y (2001). Origins and insertions of the triangular fibrocartilage complex: A histological study. Journal of Hand Surgery, 26B: 446–454.Palmer AK, Werner FW (1981). The triangular fibrocartilage complex of the wrist—anatomy and function. Journal of Hand Surgery, 6: 153–162.[Medline] [Order article via Infotrieve]Palmer AK (1989). Triangular fibrocartilage complex lesions: a classification. Journal of Hand Surgery, 14A: 594–606.[CrossRef][Medline] [Order article via Infotrieve]Thomas J, Large R, Tham SKY (2006). Sigmoid notch osteotomy for posttraumatic dorsal dislocation of the distal radioulnar joint: a case report. Journal of Hand Surgery, 31A: 1601–1604.[CrossRef][Medline] [Order article via Infotrieve]
Journal of Hand Surgery (European Volume), Vol. 32, No. 6,
705-708 (2007)
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Abstract
CASE REPORTS
