Clinical History: A 25-year-old female presents with dorsal ulnar sided wrist pain, four weeks after a fall. Coronal (1A) and axial (1B) fat-suppressed proton density-weighted images and a (1C) T2-weighted sagittal image are provided. What are your findings? What is your diagnosis?
Displaced tear of the triangular fibrocartilage complex.
Ulnar sided wrist pain is a common indication for wrist MRI and is often associated with tears of the triangular fibrocartilage complex (TFCC). The original classification system was described by Palmer, with 4 tear variations.1,2 More recently, additional tear variations have been described, involving a displaced flap or bucket-handle of triangular fibrocartilage tissue, similar to bucket-handle meniscal tears in the knee. In one recent study, these displaced TFCC tears were observed in approximately 1 of 200 wrist MRI examinations.3 After reviewing normal TFCC anatomy and the original Palmer classification system, this web clinic explains and provides several MRI examples of displaced TFCC tears. Treatment options are also discussed.
The TFCC is a group of fibrocartilaginous and ligamentous structures, serving as a shock absorber between the distal ulna and adjacent carpal bones, and a stabilizer of the distal radioulnar joint and adjacent carpus. The most important structure of the TFCC is the triangular fibrocartilage (TFC) proper, a triangular-shaped piece of fibrocartilage with attachments along the medial radius, and along the foveal and styloid portions of the distal ulna. The central portion of the TFC is only 1-2 mm thick and relatively avascular, whereas the periphery is thicker and vascular. The peripheral portions of the TFCC can be categorized by their ulnar (medial), volar, and dorsal locations. The ulnar (medial) structures include the meniscus homologue (MH) and ulnar collateral ligament (UCL). The volar structures include the volar radioulnar ligament (vRUL), ulnotriquetral (UT) and ulnolunate (UL) ligaments. The dorsal structures include the dorsal radioulnar ligament (dRUL) and extensor carpi ulnaris (ECU) tendon sheath. Some authors have also described a dorsal ulnotriquetral ligament (dUT). 4,5
Palmer Classification of TFCC Tears
In Palmer’s original classification,1,2 TFCC tears are divided into traumatic (Class 1) and degenerative (Class 2) lesions. Class 1A lesions (figure 8a) are tears of the TFC proper, located just medial to the radial attachment, usually slit-like and 1-2 mm in AP width. Class 1B lesions (figure 8b) involve a traumatic avulsion along the ulnar attachments of the TFC (such as the styloid or foveal attachments), which may or may not be accompanied by an ulnar styloid fracture. Class 1B lesions are usually associated with distal radioulnar joint instability. Class 1C lesions (figure 8c) are distal avulsions of the TFCC involving the carpal attachments of the ulnolunate or ulnotriquetral ligaments. Class 1C lesions frequently result in ulnar carpal instability, manifest by volar translocation of the ulnar carpus relative to the ulna or radius. Class 1D lesions (figure 8d) involve a traumatic detachment along the radial attachment of the TFC, which can be seen with or without a fragment of bone. Class 2 lesions are chronic degenerative injuries and excluded from this discussion.
While useful, the original Palmer classification also has several limitations.6 Tears involving volar or dorsal radioulnar ligaments are not categorized. Ulnar sided (1B) tears encompass many locations which could be subcategorized (e.g., foveal, meniscus homologue, ulnar collateral ligament, ECU subsheath). Tear thickness (e.g., full/partial) and configuration (e.g., flap, horizontal) are not included. Combined tear types are also excluded.
Reported variations of displaced TFCC Tears
Three variations of displaced TFCC tears have been reported and do not fall into the original Palmer classification system. In 2011, Theumann et al.7 reported a “bucket-handle” TFCC tear with partial separation and distal displacement of the (peripherally-located) radioulnar ligaments from the (centrally-located) TFC proper. This complex tear was considered a combination of class 1B and 1C, resulting from tears at the TFC styloid attachment and dorsal ulnotriquetral ligament. The TFC foveal attachment and volar ulnotriquetral ligament were also noted to be intact (figure 9).
In 2018, Jose et al.8 reported two additional patients with displaced TFCC tears. The first type predominantly involved tearing along the ulnar peripheral attachments, with a resultant bucket-handle displaced TFC disk flipped into the prestyloid recess (figure 11). With this tear, the authors also noted a torn meniscus homologue, frayed ECU sheath, scarred UT ligaments, and positive ulnar variance.
Jose et al. also reported another displaced bucket-handle TFCC tear, with an articular disc fragment flipped into the distal radioulnar joint (figure 11). This patient was also noted to have a positive ulnar variance and presumed tearing of the dorsal ulnocarpal ligaments. The unknown case at the introduction of this web clinic (figures 1, 2) best fits with this tear pattern. Often on MRI, a displaced flap pedicle can be visualized and connected to the native TFC; this has been described as the “comma” sign.3
Initial treatment of TFCC tears is typically conservative, involving rest, physical therapy, and corticosteroid injections.9 If conservative treatment fails, multiple surgical options exist and are guided by the vascularization of the tear site.6-8 Because the central portion of the disc is avascular, Palmer class 1A tears are treated with debridement and not repair. The peripheral portion of the disc is vascularized, and therefore class 1B and 1C can be repaired (usually arthroscopically). 1D tears may be repaired with various techniques, depending on the presence of concomitant injuries and stability of the DRUJ.6 The presence of DRUJ instability also increases the likelihood of surgical benefit. Approximately 80% of DRUJ stability is provided by the TFCC, and especially by the dorsal and volar radioulnar ligaments.8 Munk et al. also reported that Palmer class 1C lesions are significantly more associated with DRUJ instability than other the Palmer class injuries.8,10 Ulnar shortening osteotomy and arthroscopic wafer ulnar resection may also be performed to decrease the axial load upon the TFCC.6 At arthroscopy, the normal TFC is taught, exhibiting a “trampoline” effect. A soft and lax TFC has been described as a positive trampoline sign, indicating a peripheral TFC tear.11 A hook test is also used to evaluate the peripheral TFCC, by placing a probe under the ulnar attachments. A positive hook test indicates disruption of the foveal fibers, as the ulnar margin of the disc displaces toward the center for the radiocarpal joint.10 Confirmation of the foveal disruption can be confirmed with dedicated arthroscopy of the DRUJ.11 To diagnose displaced TFCC flaps extending into the DRUJ, arthroscopy of the DRUJ is often required. DRUJ arthroscopy is often not routinely performed, and therefore these displaced TFCC flaps may be missed at surgery.3 MRI remains a particularly useful preoperative tool, as displaced TFCC tears can be associated with pain, joint obstruction, mechanical symptoms, and decreased supination.3,8
Displaced tears of the TFCC are a variation of the original Palmer classification system and may be associated with pain and mechanical symptoms. Displaced TFCC tears can be confidently diagnosed with MRI, particularly when a “comma” sign is present. Because displaced flaps extending into the DRUJ are not reliably seen from the standard arthroscopic approach, preoperative MRI is particularly helpful in a patient with ulnar-sided wrist pain.
- Palmer AK. Triangular fibrocartilage complex lesions-A classification. J Hand Surg Am. 1989;14A(4):594-606. doi:10.1007/978-1-4471-5451-8_93 ↩
- Palmer AK. Triangular fibrocartilage disorders: Injury patterns and treatment. Arthrosc J Arthrosc Relat Surg. 1990;6(2):125-132. doi:10.1016/0749-8063(90)90013-4 ↩
- Boutin RD, Fritz RC. Displaced flap tears of the triangular fibrocartilage complex: Frequency, flap location, and the “Comma” sign on wrist MRI. Am J Roentgenol. 2021;217(3):707-708. doi:10.2214/AJR.20.25437 ↩
- Tay SC, Tomita K, Berger RA. The “Ulnar Fovea Sign” for Defining Ulnar Wrist Pain: An Analysis of Sensitivity and Specificity. J Hand Surg Am. 2007;32(4):438-444. doi:10.1016/j.jhsa.2007.01.022 ↩
- Theumann NH, Pfirrmann CWA, Antonio GE, et al. Extrinsic carpal ligaments: Normal MR arthrographic appearance in cadavers. Radiology. 2003;226(1):171-179. doi:10.1148/radiol.2261011715 ↩
- Ng AWH, Griffith JF, Fung CSY, et al. MR imaging of the traumatic triangular fibrocartilaginous complex tear. Quant Imaging Med Surg. 2017;7(4):443-460. doi:10.21037/qims.2017.07.01 ↩
- Theumann N, Kamel EM, Bollmann C, Sturzenegger M, Becce F. Bucket-handle tear of the triangular fibrocartilage complex: Case report of a complex peripheral injury with separation of the distal radioulnar ligaments from the articular disc. Skeletal Radiol. 2011;40(12):1617-1621. doi:10.1007/s00256-011-1269-1 ↩
- Jose J, Arizpe A, Barrera CM, Ezuddin NS, Chen D. MRI findings in bucket-handle tears of the triangular fibrocartilage complex. Skeletal Radiol. 2018;47(3):419-424. doi:10.1007/s00256-017-2796-1 ↩
- Kyle Casadei; John Kiel. Triangular Fibrocartilage Complex. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK537055/. Published 2021. Accessed May 12, 2021. ↩
- Munk B, Jensen SL, Olsen BS, Kroener K, Ersboell BK. Wrist stability after experimental traumatic triangular fibrocartilage complex lesions. J Hand Surg Am. 2005;30(1):43-49. doi:10.1016/j.jhsa.2004.08.009 ↩
- Greene R, Kakar S. The Suction Test: A Novel Technique to Identify and Verify Successful Repair of Peripheral Triangular Fibrocartilage Complex Tears. J Wrist Surg. 2017;06(04):334-335. doi:10.1055/s-0037-1599125 ↩