The triangular fibrocartilage complex on high-resolution 3 T MRI in healthy adolescents: the thin line between asymptomatic findings and pathology

Abstract

Objective: The objective of the study is to provide a reference for morphology, homogeneity, and signal intensity of triangular fibrocartilage complex (TFCC) and TFCC-related MRI features in adolescents.

Materials and methods: Prospectively collected data on asymptomatic participants aged 12-18 years, between June 2015 and November 2017, were retrospectively analyzed. A radiograph was performed in all participants to determine skeletal age and ulnar variance. A 3-T MRI followed to assess TFCC components and TFCC-related features. A standardized scoring form, based on MRI definitions used in literature on adults, was used for individual assessment of all participants by four observers. Results per item were expressed as frequencies (percentages) of observations by all observers for all participants combined (n = 92). Inter-observer agreement was determined by the unweighted Fleiss' kappa with 95% confidence intervals (95% CI).

Results: The cohort consisted of 23 asymptomatic adolescents (12 girls and 11 boys). Median age was 13.5 years (range 12.0-17.0). Median ulnar variance was -0.7 mm (range - 2.7-1.4). Median triangular fibrocartilage (TFC) thickness was 1.4 mm (range 0.1-2.9). Diffuse increased TFC signal intensity not reaching the articular surface was observed in 30 (33%) observations and a vertical linear increased signal intensity with TFC discontinuation in 19 (20%) observations. Discontinuation between the volar radioulnar ligament and the TFC in the sagittal plane was seen in 23 (25%) observations. The extensor carpi ulnaris was completely dislocated in 10 (11%) observations, more frequent in supinated wrists (p = 0.031). Inter-observer agreement ranged from poor to fair for scoring items on the individual TFCC components.

Conclusion: MRI findings, whether normal variation or asymptomatic abnormality, can be observed in TFCC and TFCC-related features of asymptomatic adolescents. The rather low inter-observer agreement underscores the challenges in interpreting these small structures on MRI. This should be taken into consideration when interpreting clinical MRIs and deciding upon arthroscopy.

Keywords: Adolescent; Magnetic resonance imaging; Triangular fibrocartilage; Wrist injuries.

Fig. 1

Coronal proton-density weighted fat-saturated MRI showing TFC morphology delineated in white and indicated by the white arrowheads a as a slightly radially tilted asymmetrical bowtie, b as a shorter, thicker and more horizontal structure, and c as a thinner and more stretched structure. Image c also shows the meniscus homolog morphology as a diffuse triangular shaped hypo-intensity (black arrowhead) directly lateral from the prestyloid recess

Fig. 2

Coronal proton-density weighted fat-saturated MRI showing TFCs (indicated with arrowheads) with a hypo-intense signal intensity, b diffuse hyper-intense signal intensity not extending through the articular surface, c vertical linear hyper-intense signal intensity with discontinuation of the disc, and d a broader variation on this vertical line. Image a also shows the proximal (short arrow) and distal lamina (long arrow) as homogeneous hypo-intense bands, separated by the ligamentum subcruentum shown as a hyper-intense signal intensity (asterisk)

Fig. 3

Sagittal proton-density weighted MRI showing the volar RUL as a structure that is a continuous and indiscernible with the TFC (arrowhead) and b discontinuous with the TFC (arrowhead) in between the ulnar head (diamonds) and lunate bone (asterisks)

Fig. 4

Axial T2 weighted fat-saturated MRI showing the ECU tendon (arrowheads) position a completely within, b partially within, and c completely outside its groove (long arrows). All three wrist positions were scored as a supinated wrist position with the ulnar head in dorsal rotation. Image b and c also show a substantial amount of DRUJ effusion (short arrows)

Fig. 5

Coronal proton-density weighted fat-saturated MRI showing the a conical shaped prestyloid recess (arrowhead), b tubular shaped prestyloid recess (arrowhead), and c saccular shaped prestyloid recess (arrowhead)