Keywords
triangular fibrocartilage complex - foveal - transosseous repair - cadaveric - optimal
suture location
Triangular fibrocartilage complex (TFCC) injury can lead to distal radioulnar joint
(DRUJ) instability and ulnar-sided wrist pain. The deep portion of the TFCC inserts
in the fovea of the ulnar head and is critical to DRUJ stability. There are numerous
methods to repair the TFCC, but there is no consensus on whether transcapsular suture[1]
[2]
[3] or transosseous suture[4]
[5]
[6]
[7]
[8]
[9] is more effective.
The optimal suture location of the TFCC and fovea should allow full range of movement
at the wrist without causing long-term degeneration of the TFCC suture site. Only
a few studies discussed the optimal site of suture placement in the fovea and TFCC
for transosseous suture repair. To clarify the optimal site of suture placement, we
used an anatomical model to investigate various suture positions in the TFCC and fovea.
The model was based on studies undertaken to clarify the optimal site of bone tunnel
placement in anterior cruciate ligament (ACL) reconstruction in the knee.[10]
[11] Hoogland and Hillen[10] measured the length pattern of 12 different positions (three femoral tunnels and
four tibial tunnels) from extension to flexion with a plastic-coated steel cord fixated
to the tibial tuberosity with a staple and placed through the femoral and tibial tunnels
under a tension of 5 kg. The change in the cord's length was measured between extension
and flexion to determine the tunnel position at which there are minimal length changes
in the steel cord. We adapted this measurement method in our anatomical model. The
biomechanics of the ACL and TFCC are very different, but the deep portion of the TFCC
connects with the TFCC disc and fovea in the same manner as the ACL connects with
the femur and tibia. This study aimed to investigate the locations where there are
minimal length changes in the sutures between the TFCC and the foveal tunnels and
the ideal reconstruction route in the event of injury to the foveal ligament connecting
the two components.
Materials and Methods
We used seven fresh-frozen forearms with elbows (four from the right and three from
the left) from three male and four female white cadavers with a mean age of 72.9 years
(range, 63–83 years). Before the study, all musculature was removed, and the radiocarpal
joint was disarticulated. All ligaments and the interosseous membrane of the forearm
were preserved except 5 cm from the distal end of the ulna. The ulnar shaft was osteotomized
5 cm from the distal end and inverted, and the TFCC was divided from the fovea ([Fig. 1]). The osteotomized ulna was stabilized by a five-hole plate and 3.5-mm cortical
screws (Stryker Small Fragment Set; Stryker, Mahwah, NJ). In addition, before cutting
the ulna, the plate was predrilled and prepositioned. The elbow was fixed at 90 degrees
flexion using a 2.4-mm K-wire inserted from the proximal ulna to the distal humerus,
and the ulna was mounted to a customized jig. The setup allowed for supination and
pronation of the radius around the ulna ([Fig. 2]).
Fig. 1 The ulnar shaft was osteotomized 5 cm from the distal ulna and inverted. Then the
TFCC was incised at the fovea. The dotted line marks the margin of the TFCC annular
disc. TFCC, triangular fibrocartilage complex.
Fig. 2 The ulna was mounted to a customized jig. The suture line moved distally and proximally
accompanying with the forearm rotation. The degree of suture displacement was measured
using a digital caliper through a loupe at the five predetermined rotation positions.
[Fig. 3] illustrates the suture locations in the TFCC and fovea. The TFCC reference marker,
TFCC 5, was placed at the ulnar apex of the TFCC disc, whereas the foveal reference
marker, fovea 2, was placed at the center of the circle formed by the ulnar head overlooking
the distal end of the ulna from an end-on view (i.e., fovea 2 is the theoretical center
of rotation) ([Fig. 4]).
Fig. 3 Diagrammatic representation of the suture locations on the TFCC and the fovea. TFCC,
triangular fibrocartilage complex.
Fig. 4 Ulna from an end-on view. The circumference of the distal ulnar articular surface
is identified as a precise circle, with its radius marked with sharp sign (#). O indicates
the position of fovea 2.
The TFCC was sutured at six points (TFCCs 1–6) using inelastic sutures (Stealth Code
Red Braid, 0.22 mm; Spider Wire, Spirit Lake, IA) by horizontal mattress technique
([Figs. 5] and [6]). There were two limbs on the suture of each TFCC point; the bite distance of the
horizontal mattress was 1.5 mm, and the distance between the respective suture locations
was 2 mm ([Fig. 3]). Six osseous tunnels were created in the fovea (foveae 1–6). A small bony tunnel
was created in the fovea with a 19-gauge needle, and the distance between tunnels
was 2 mm. Each of the six TFCC sutures was then placed through each of the six bone
tunnels, resulting in 36 combinations of TFCC locations and foveal tunnels ([Figs. 3] and [5]). A weight of 300 g was applied to each suture ([Fig. 6]).
Fig. 5 The six suture locations in the TFCC and six bone tunnels in the fovea. The suture
was passed from the TFCC to the foveal bone tunnels. The red arrow points to the suture
combination TFCC 1–fovea 1. TFCC, triangular fibrocartilage complex.
Fig. 6 Displacement of the suture line. The suture line moved distally and proximally (white
arrow) as the forearm was manually rotated. Two K-wires inserted in the radius are
parallel, and the K-wire points to the protractor. TFCC, triangular fibrocartilage
complex.
From each of the five positions between maximal supination and maximal pronation (maximal
supination, 45 degrees of supination, neutral position, 45 degrees of pronation, and
maximal pronation), the degree of suture displacement was measured using a digital
caliper (resolution, 0.01 mm; Carrera Precision, Guangdong, China) ([Fig. 6]). The radius is manually rotated to these five positions, which are set by pointing
a K-wire inserted into the radius of the protractor ([Figs. 2] and [6]). All measurements were taken at the same time interval after applying the 300-g
weight to allow the soft tissue mattress to recover between each loading. The maximum
and minimum lengths of the suture line were measured during forearm rotation, and
the difference was defined as the suture displacement. An optimal suture location
was defined as having the shortest displacement distance.
Statistical Analysis
Two-way analysis of variance and multiple comparison analysis were performed. The
analysis factors were TFCC, fovea, and TFCC × fovea. The IBM SPSS Statistics 20 software
(Statistical Package for Social Sciences, Armonk, NY) was used for the statistical
analyses. A p-value of < 0.05 was considered statistically significant.
Results
The mean suture displacement was 2.4 ± 1.6 mm (range, 0–6.2 mm) over the entire range
of forearm rotation. The mean forearm pronation was 76.0 ± 8.7 degrees (range, 20–90
degrees), and all specimens had forearm pronation greater than 65 degrees in all 36
combinations except one specimen with 20 degrees in the TFCC 1–fovea 1 combination.
The mean forearm supination was 76.5 ± 7.4 degrees (range, 55–90 degrees), and all
of the values had forearm supination greater than 70° except two specimens with 55
degrees in TFCC 1–fovea 1 combination.
The homogeneity of variance held for any combination of all levels in Levine's test
for equality of variance (p = 0.086). Statistical analysis was performed on the fovea because the interaction
between the TFCC and the fovea demonstrated significant difference in the between-subjects
effects (p = 0.001).
Subeffect tests were performed using the Bonferroni method to test pairwise comparisons
among foveae 1 to 6 in each TFCC position. There are significant differences in foveae
1, 3, 4, and 6 (all p < 0.005), but none in foveae 2 (p = 1.00) and 5 (p > 0.2), which means that there is no significant difference in suture displacement
among the TFCC groups belonging to foveae 2 and 5, respectively. The mean suture displacement
for fovea 2 was 0.7 ± 0.6 mm (range, 0–2.4 mm), and the mean suture displacement for
fovea 5 was 1.5 ± 0.8 mm (range, 0.1–3.0 mm). The significant differences among all
pairs of means in this study are shown in [Table 1] (p < 0.05).
Table 1
Results of the two-way analysis of variance and multiple comparison analysis
|
Fovea
|
(I) TFCC
|
(J) TFCC
|
p-Value[a]
|
|
1
|
1
|
3
|
0.001
|
|
2
|
4
|
0.007
|
|
|
5
|
0.018
|
|
3
|
4
|
0.000
|
|
|
5
|
0.000
|
|
3
|
3
|
5
|
0.039
|
|
4
|
1
|
4
|
0.037
|
|
|
5
|
0.001
|
|
2
|
5
|
0.042
|
|
3
|
5
|
0.004
|
|
6
|
1
|
3
|
0.000
|
|
3
|
4
|
0.000
|
|
|
5
|
0.002
|
|
4
|
6
|
0.013
|
Abbreviation: TFCC, triangular fibrocartilage complex.
a Only values showing significant differences are presented here (p < 0.05).
In an additional statistical analysis, we compared each fovea group, based on the
data points of TFCC 1 to 6, using the Kruskal–Wallis' analysis for multiple comparisons
([Table 2]). The fovea 2 group had significantly shorter suture displacement than the other
fovea groups, except for the fovea 5 group. The fovea 5 group also had significantly
shorter suture displacement than the other fovea groups, except for the fovea 2 group.
The p-value for the fovea 2 group versus the fovea 5 group was 0.069, which was very close
to a level of significance of 0.05. Therefore, the fovea 2 group had the shortest
values and was followed by the fovea 5 group ([Figs. 7] and [8]). [Fig. 8] shows that the dotted line of fovea 2 has the minimum displacement regardless of
TFCC locations (range, 0.4–0.9 mm). We believe that clinically, a displacement of
0.9 mm is acceptable because it represents very little movement and may not cutout
TFCC substance even with repeated wrist movement. Accordingly, 0.9 mm was set as the
upper limit value of the acceptable range; the data for fovea 2, fovea 5–TFCC 4, and
fovea 5–TFCC 5 conform with this range.
Fig. 7 Suture displacement distance of the different fovea–TFCC combinations. Foveae 2 and
5 have substantially smaller degrees of movement. TFCC, triangular fibrocartilage
complex.
Fig. 8 Suture displacement distance of the different fovea–TFCC combinations shown in [Fig. 7], with the TFCCs in the x-axis. TFCC, triangular fibrocartilage complex.
Table 2
Results of the Kruskal–Wallis' analysis
|
Sample 1–sample 2
|
Adjusted p-Value[a]
|
|
Fovea 2–fovea 1
|
0.000
|
|
Fovea 2–fovea 3
|
0.000
|
|
Fovea 2–fovea 4
|
0.000
|
|
Fovea 2–fovea 6
|
0.000
|
|
Fovea 5–fovea 1
|
0.003
|
|
Fovea 5–fovea 3
|
0.001
|
|
Fovea 5–fovea 4
|
0.000
|
|
Fovea 5–fovea 6
|
0.000
|
|
Fovea 2–fovea 5
|
0.069
|
a Only values showing a significant difference (p < 0.05) are presented; fovea 2–fovea 5 values are presented here.
Discussion
TFCC injury can result in ulnar-sided wrist pain and loss of wrist function.[7] In particular, the deep portion of the TFCC acts as the main stabilizer of the DRUJ,
and any disruption to the foveal insertion can result in instability.[12] The use of the transosseous suture technique for repairing lost TFCC foveal insertion
integrity has been widely reported to be very effective in restoring DRUJ stability.[4]
[5]
[6]
[7]
[8]
[9]
[13]
[14]
To repair a TFCC foveal insertion, Nakamura et al[8] passed a suture through the TFCC and a bone tunnel that was placed at the foveal
isometric point. Atzei et al[13]
[14] sutured the TFCC by inserting a suture anchor under a fluoroscope. Iwasaki and Minami[9] reported successful TFCC suture repair with one small osseous tunnel in the fovea
using a 2.9-mm cannulated drill.
However, to the best of our knowledge, there were no reports on whether the optimal
suture location was in the TFCC substance or the fovea. The purpose of this study
was to clarify the best location for transosseous repair.
The radius rotates around the ulna, and the theoretical rotation center is the center
of a circle, if the distal ulnar head is considered a circle. This theoretical rotation
center has been regarded as the isometric point. Therefore, the TFCC has been sutured
to this theoretical rotation center in the past. For the purposes of our study, fovea
2 was chosen as the theoretical center of rotation and reference marker, which was
similar to the process of identifying the isometric point in ACL reconstruction in
the knee.[10]
[11] We examined the optimal suture location for both the fovea and the TFCC for transosseous
repair in a similar method to that used to examine the optimal positions for femoral
and tibial osseous tunnels for ACL reconstruction.
This study has several limitations. First, the cadavers were of old age, resulting
in less elastic TFCC tissue, which may not be representative of clinical reality.
Second, the ulnocarpal ligaments were transected in the cadavers because the specimens
were disarticulated at the wrist. However, this study focused on a transosseous TFCC
repair model to establish optimal suture fixation; therefore, only the deep portion
of the TFCC and its relationship to the fovea were evaluated. We did not evaluate
the superficial portion of the TFCC, the extensor carpi ulnaris subsheath, the ulnolunate
ligament, the ulnotriquetral ligament, or the interosseous membrane of the forearm
in this study. It is important to ensure the integrity of the TFCC in each specimen.
If there was a tear, secondary stabilizing structures could be stretched, causing
a different pattern of motion during supination and pronation, but there was no apparent
tear in any of the specimens.
Despite the aforementioned limitations, we believe we have useful results that can
be translated to clinical use. According to our data, the optimal bone tunnels on
the fovea for transosseous TFCC repair include foveae 2 and 5. Interestingly, if any
of the TFCC locations is repaired at the location of fovea 2, there is minimal suture
displacement. If fovea 5 is used, the optimal TFCC location is 4 or 5. Practically,
this means that the surgeon should aim for fovea 2 and TFCC 4 or 5 locations to attach
the TFCC successfully to the foveal isometric point. The challenge would be to find
this center of the distal ulnar circle intraoperatively, when exposure is not as extensive
as in cadaveric laboratory setting.
