MRI Web Clinic — January 2022

Displaced Triangular Fibrocartilage Cartilage Complex Tears
Leon R. Toye, M.D.

 

 

 

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?

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Figure 1

Findings

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Figure 2:

2a: Coronal fat-suppressed proton density-weighted image demonstrates a full thickness tear within the central triangular fibrocartilage (small arrow). A displaced flap (curved arrow) extends toward the distal radioulnar joint.
2b: Axial fat-suppressed proton density-weighted image demonstrates the displaced flap (arrow) located within the volar aspect of the distal radioulnar joint.
3c: Sagittal T2-weighted image at level of the pisiform (P) and triquetrum (T) again demonstrates the displaced triangular fibrocartilage flap (arrow) along the volar aspect of the distal ulna (U).

Diagnosis

Displaced tear of the triangular fibrocartilage complex.

Introduction

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.

Anatomy

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

 

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Figure 3:

TFC: Triangular fibrocartilage proper
dRUL: Dorsal radioulnar ligament
vRUL: Volar radioulnar ligament
ECU: Extensor carpi ulnaris tendon sheath
MH: Meniscus homologue
UCL: Ulnar collateral ligament
UT: Ulnotriquetral ligament
UL: Ulnolunate ligament
Arrowhead: Prestyloid recess

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Figure 4:

Coronal proton density-weighted images are presented from volar to dorsal.
4a: The volar radioulnar ligament (VRUL) is a volar peripheral thickening of the TFCC. The volar ulnotriquetral (UT) and ulnolunate (UL) ligaments are highlighted with dashed lines.
4b: The ulnar collateral ligament (UCL) can be seen along the ulnar margin of the TFCC with the adjacent meniscus homologue (*).
4c: The styloid (S), foveal (F), and radial (R) attachments of the TFC proper (*).
4d: The extensor carpi ulnaris tendon (ECU) is depicted with multiple arrows.
4e: The dorsal radioulnar ligament (DRUL) is a dorsal peripheral thickening of the TFCC.

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Figure 5:

Figure 5: Normal TFCC Anatomy - sagittal plane.
Sagittal proton density-weighted images are presented from medial to lateral.
5a, b: At the level of the ulna (U) and triquetrum (T). The volar radioulnar ligament (vRUL) and dorsal radioulnar ligament (dRUL) (curved red arrows) attach to the periphery of the TFC proper (*). The volar ulnotriquetral (vUT) ligament is located slightly more distally and depicted with a straight yellow arrow.
5c: Slightly more laterally at the ulna (U), lunate (L) and hamate (h), the volar ulnolunate (vUL) is depicted with a yellow arrow.

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Figure 6:

Figure 6: Normal TFCC Anatomy - axial plane.
Axial post-arthrographic fat-suppressed T1-weighted images are presented from proximal to distal.
6a: At the level of the distal radius (R) and ulna (U), the extensor carpi ulnaris tendon (ECU) is seen along the dorsal ulnar groove.
6b: More distally at the level of the TFCC, the thin TFC proper (*) is barely seen. The TFC proper attaches to the dorsal and volar radioulnar ligaments, which are peripheral thickenings (dashed yellow lines). Normal arthrographic contrast is present within the proximal pisotriquetral recess (r).
6c, d: More distally at the level of the lunate (L), and triquetrum (T) the volar ulnolunate and ulnotriquetral ligaments are demonstrated (yellow arrows). Normal arthrographic contrast is present within the pre-styloid recess (r).

 

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.

 

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Figure 8:

Figure 8: Illustrations of Palmer Class 1 (Traumatic) TFCC Tears
8a: (Class 1A) Perforation along the central substance of the TFC.
8b: (Class 1B) Avulsion along the ulnar attachments of the TFC, with or without a distal ulnar fracture.
8c: (Class 1C) Avulsion along the distal (lunate and triquetral) attachments of the TFCC.
8d: (Class 1D) Avulsion along the radial attachments of the TFC, with or without a radial fracture at the sigmoid notch.

 

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).

 

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Figure 9:

Figure 9: Displaced TFCC tear Illustration – Variation 1 (TFC separated from RULs)
Rendering demonstrating the first reported variation of a displaced bucket-handle mechanism of TFCC tear, with separation of the radioulnar ligaments from the TFC. The styloid attachment of the TFC is torn, with an intact foveal attachment. The dorsal ulnotriquetral ligament (dUT) is torn, with intact volar ulnotriquetral (UT) and ulnolunate (UL) ligaments.

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Figure 10:

Figure 10: Displaced TFCC tear – Variation 1 (TFC separated from RULs)
10a-b: Coronal gradient echo images (along the dorsal to central wrist) demonstrate tearing of the dorsal ulnotriquetral ligament (D) and tearing along the TFC styloid attachment (S).
10c-d: Coronal gradient echo images (along the volar wrist) demonstrate the volar radioulnar ligament (curved red arrows) displaced distally and separated from the TFC proper (*).

 

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.

 

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Figure 11:

Figure 11: Displaced TFCC tear Illustration – Variation 2 (Into prestyloid recess)
Rendering demonstrating the second reported variation of a displaced bucket-handle mechanism of TFCC tear, with the articular disc flipped into the prestyloid recess.

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Figure 12:

Figure 12: Displaced TFCC tear – Variation 2 (Into prestyloid recess) Example 1
12a: Coronal fat-suppressed proton density-weighted image demonstrates a complex tear of the TFCC involving the central TFC disc (arrow) and dorsal radioulnar ligament (arrowhead), both displaced distally into the prestyloid recess, between the ulnar styloid and triquetrum.
12b: Sagittal T1-weighted image at the level of the triquetrum (T) and pisiform (P), demonstrates displaced torn TFC tissue (*) extending toward the prestyloid recess. The dorsal radioulnar ligament is torn and attenuated (arrow).
12c: Axial fat-suppressed proton density-weighted image demonstrating the displaced torn TFCC flap (*) extending toward the prestyloid recess. The extensor carpi ulnaris tendon (ECU) is labeled for reference.

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Figure 13:

Figure 13: Displaced TFCC tear – Variation 2 (Into prestyloid recess) Example 2
13a, b: Coronal fat-suppressed proton density-weighted images demonstrates a complex degenerative tear of the TFCC with central TFC tissue displaced distally into the prestyloid recess (curved arrows). Proximal carpal row arthritis and partial carpectomy changes are also present.

 

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

 

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Figure 14:

Figure 14: Displaced TFCC tear Illustration – Variation 3 (Into DRUJ)
Rendering demonstrating the third reported variation of a displaced bucket-handle mechanism of TFCC tear, with the articular disc flipped into the distal radioulnar joint.

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Figure 15:

Figure 15: Displaced TFCC tear – Variation 3 (Into DRUJ) Example 1
15a, b: Coronal fat-suppressed proton density-weighted images demonstrate a complex bucket-handle tear of the TFCC, with a large unstable articular disc fragment flipped intra-articularly into the DRUJ (arrows). The flap pedicle is connected the TFC, consistent with the “comma” sign.
15c, d: Axial fat-suppressed proton density-weighted images demonstrate the displaced TFCC fragment extending into the volar aspect of the DRUJ (arrows).
15e: Sagittal proton density-weighted image demonstrates a torn and truncated dorsal radioulnar ligament (red arrow) with an intact volar radioulnar ligament (white arrow).

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Figure 16:

Figure 16: Displaced TFCC tear – Variation 3 (Into DRUJ) Example 2
16a, b: Coronal fat-suppressed proton density-weighted images demonstrate a complex bucket-handle tear of the TFCC, with a displaced articular disc fragment flipped into the DRUJ (arrows).
16c: Axial fat-suppressed proton density-weighted image demonstrates the displaced TFCC fragment extending into the dorsal aspect of the DRUJ (arrow).
16d: Sagittal T2-weighted image demonstrates a torn TFCC fragment extending into the dorsal aspect of the DRUJ (arrow).

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Figure 17:

Figure 17: Displaced TFCC tear – Variation 3 (Into DRUJ) Example 3
17a: Coronal fat-suppressed proton density-weighted image demonstrates a displaced bucket-handle tear of the TFCC, with articular disc fragment flipped into the DRUJ (arrow).
17b: Axial fat-suppressed proton density-weighted image demonstrates the displaced TFCC fragment extending into the volar aspect of the DRUJ (arrow).
17c: Sagittal proton density-weighted image demonstrates the torn TFCC fragment extending into the volar aspect of the DRUJ (arrow).

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Figure 18:

Figure 18: Displaced TFCC tear – Variation 3 (Into DRUJ) Example 4
18a: Coronal fat-suppressed proton density-weighted images demonstrate tearing along the styloid (S) and foveal (F) attachments of the TFC.
Coronal fat-suppressed proton density (18b), axial T1 (18c), and sagittal fat-suppressed T2-weighted (18d) images demonstrate a displaced TFCC flap (“comma” sign) extending into the volar aspect of the DRUJ (arrows).

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Figure 19:

Figure 19: Displaced TFCC tear – Variation 3 (Into DRUJ) Example 5
19 a, b: Coronal fat-suppressed proton density weighted images demonstrate complex tearing involving the dorsal radioulnar ligament (D), central TFC (C) the styloid attachment (S) of the TFCC.
Coronal fat-suppressed proton density weighted images (19 c, d) and axial T1 weighted image demonstrate a resultant wavy displaced segment flipped into the volar aspect of the DRUJ (curved red arrows).

 

Treatment

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

 

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Figure 20:

Figure 20: Surgical treatment of original test case
The patient from our introductory case underwent arthroscopy after the MRI of figures 1 and 2. A full thickness tear of the TFC was confirmed at surgery, and a probe can be seen within the defect (20a). The displaced flap within the DRUJ was also confirmed (20b). The flap was resected followed by debridement of the tear (20c). Arthroscopic photos courtesy of William Gramig, MD, Greensboro, NC.

 

Summary

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.

References

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. Kyle Casadei; John Kiel. Triangular Fibrocartilage Complex. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK537055/. Published 2021. Accessed May 12, 2021.
  10. 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
  11. 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