Keywords
reattachment - triangular fibrocartilage complex - extensor carpi ulnaris - foveal
avulsion - interference screw
The triangular fibrocartilage complex (TFCC) is a fibrocartilage-ligament complex
in the ulnar side of the wrist, which consists of the triangular fibrocartilage (TFC;
also termed the articular disc or disc proper), the meniscus homologue, the radioulnar
ligament (RUL), the ulnolunate ligament, the ulnotriquetral ligament, the ECU sheath
floor, and the ulnar joint capsule.[1]
[2] The TFCC stabilizes the distal radioulnar joint (DRUJ) and ulnocarpal joint, distributes
load between the ulna and ulnar carpus, and allows multidirectional motion of the
wrist, such as flexion-extension, radial and ulnar deviation, as well as forearm rotation.[1]
[2]
The RUL, which is the proximal component of the TFCC, is the primary stabilizer of
the DRUJ.[3] In histology, the fibers of the RUL arise nearly vertically from the fovea of the
ulna and base of the ulnar styloid ([Fig. 1]).[4]
[5] It then curls radially and separates into palmar and dorsal portions, which pass
through the proximal portion of the TFCC, and finally attaches to the radiodistal
edge of the sigmoid notch. This unique origin of the fovea-attaching fibers of the
RUL allows easy twisting during pronation-supination, which allows nearly 180° of
forearm rotation.
Fig. 1 Coronal histology of the TFCC demonstrates a nearly vertical origin of the RUL from
the fovea of the ulna (arrow).
Patients with an injury to the TFCC present with ulnar-side wrist pain, DRUJ instability,
and/or loss of pronation-supination range. Recent biomechanical and clinical studies
have shown that an avulsion of the RUL at the ulnar fovea may result in severe DRUJ
instability.[6]
[7]
[8]
[9] Foveal avulsion of the TFCC was not described in the Palmer classification,[10] Atzei et al later subclassified Palmer's 1B (peripheral TFCC tear) into a distal
tear, a proximal tear (i.e., foveal avulsion) and a combined tear.[11]
Surgical treatment of a foveal avulsion of the RUL is controversial. An ulnar shortening
osteotomy (USO) may stabilize the DRUJ because the TFCC is tightened up by the pulling
effect from the shortened ulna.[9] However, USO is not indicated in patients with ulnar neutral or ulnar negative variance
because of the risk of incongruity between the ulnar head and the sigmoid notch as
well as the increased joint pressure after a shortening.[12] When the TFCC is completely avulsed from the fovea ([Fig. 2]), an ulnar shortening no longer restabilizes the DRUJ.[13] Arthroscopic[7]
[14]
[15] or open[6]
[9]
[16]
[17] repair techniques for foveal avulsions have been recently described. If the foveal
avulsion of the TFCC is chronic (> 6 months), however, it is difficult to repair either
arthroscopically or in an open fashion.[7] Reconstructive techniques have included reconstruction of the RUL using the flexor
carpi ulnaris tendon,[18] palmaris longus tendon free graft[19]
[20]
[21]
[22] and Dacron artificial ligament.[23]
Fig. 2 Illustration of foveal avulsion of the triangular fibrocartilage complex (TFCC).
Since 1998, we have treated 25 wrists with a foveal detachment of the TFCC by our
original reattachment technique using a distally based half-slip of the extensor carpi
ulnaris (ECU) tendon that was anchored with an interference screw. This was a simple
reattachment technique of the TFCC to the center of the ulnar fovea, which is where
the rotational axis of the forearm passes. We retrospectively examined the clinical
outcome of this procedure.
Patients and Methods
Twenty-four patients underwent our original reattachment technique for chronic foveal
detachment of the TFCC with severe DRUJ instability with a minimum of 2 years follow
up. There were 9 male and 15 female patients. Sixteen involved the right wrist and
seven involved the left wrist, with one patient having bilateral involvement. The
mean age was 34.8 years (range 13–64). The average follow-up was 3.1 years (range
2–7 years). The mechanism of TFCC avulsion was a fall in 15 instances, sports in 4,
traffic accident in 2, and unknown in 4. There was a neutral ulnar variance in 19
patients and a positive variance in 6. There were no negative-ulnar-variance wrists.
In the positive-variance wrists, an ulnar shortening was performed to prevent ulnar
abutment before the reattachment.
The diagnosis of a foveal detachment was made with either an arthrogram or magnetic
resonance imaging (MRI). MRI findings included a high signal intensity at the fovea
([Fig. 3]). Dye leakage into the fovea was indicative of a foveal detachment on arthrogram
([Fig. 4]). We confirmed that there was a TFCC foveal avulsion through DRUJ arthroscopy. The
arthroscopic findings in these cases included a lack of tension of the RUL upon probing
with a 23G needle and a complete absence of the RUL, which was often replaced by scar.
The clinical results were evaluated preoperatively and at final follow up using our
DRUJ evaluating system,[7] pain levels, the range of pronosupination, and DRUJ stability ([Table 1]). Pre- and postoperative visual analog scale (VAS) pain measurements and grip power
were also evaluated.
Table 1
DRUJ evaluation system
|
Category
|
Levels
|
Points
|
|
Pain
|
Severe (always painful)
|
0
|
|
Moderate (pain in motion or twisting)
|
1
|
|
Mild (occasionally painful)
|
2
|
|
No pain
|
4
|
|
Range of pronation/supination
|
Less than 100°
|
0
|
|
100–119°
|
1
|
|
120–139°
|
2
|
|
140–159°
|
3
|
|
More than 159°
|
4
|
|
DRUJ stability
|
++ (no end point in any direction)
|
0
|
|
+ (at least one end point either in dorsal or palmar)
|
1
|
|
± (looser than intact contralateral side)
|
2
|
|
− (stable DRUJ)
|
4
|
Points of each category were added and evaluated as excellent (11–12 points), good
(9–10 points), fair (6–8 points), or poor (0–5 points).
Fig. 3 MRI of the foveal avulsion demonstrates a high-signal-intensity area at the fovea.
Fig. 4 Arthrogram of the foveal avulsion. The dye leakage into the fovea can be seen (white arrow).
Indication
We reserve this reconstruction technique for patients with severe DRUJ instability
due to a chronic disruption of the RUL (at least 6 months after the initial injury)
([Fig. 2]).
Radiocarpal arthroscopy can demonstrate only a loss of the trampoline effect as well
as loss of peripheral tension on the disc. DRUJ arthroscopy may often demonstrate
a complete rupture of the ulnar origin of the TFCC at the fovea ([Fig. 5]).
Fig. 5 DRUJ arthroscopy. The RUL is avulsed at the fovea.
The technique described is suitable for wrists with a neutral or negative ulnar variance.
In wrists with a positive variance, an ulnar shortening is performed to restore an
ulnar neutral variance. If the DRUJ is stable after the ulnar shortening, further
surgery is not needed. A prerequisite for this procedure is a reconstructable peripheral
rim of the TFCC that will not tear following the insertion of a tendon graft.
Contraindication
Complete destruction of the TFCC, such as in patients with rheumatoid arthritis, is
a contraindication. If the ulnar edge of the TFCC is frayed or in poor condition,
other reconstructive techniques should be used. Another contraindication is severe
degeneration or osteoarthritic change of the DRUJ, which should be treated by other
means.
Surgical Technique
A dorsal c-shaped skin incision is used with extension of the 4–5 or 6R portal for radiocarpal
arthroscopy and/or DRUJ portal for DRUJ arthroscopy. The hand is suspended in finger
traps. After the skin flap is elevated, the superficial sensory branches of the ulnar
nerve are indentified and preserved. A 3-cm longitudinal incision of the ECU sheath
at the DRUJ is made, and the ECU is retracted. After the radial ridge of the ECU subsheath
is longitudinally cut, the dorsal capsule of the DRUJ appears just beneath the ECU
subsheath. Elevating the dorsal DRUJ capsule from the ulnar head using a knife exposes
the DRUJ ([Fig. 6]). A small ring elevator is inserted in the DRUJ to dislocate the ulnar head. If
there is a detachment or horizontal tear of the TFCC, the ulnar head can be easily
dislocated.
Fig. 6 Intraoperative photograph. The ECU is retracted ulnarly. The RUL fibers are absent.
A foveal tear of the RUL is clearly visible after an additional small (5-mm longitudinal)
incision is made at the foveal origin of the RUL. Because the direction of the fovea-attaching
fibers of the RUL is nearly vertical, a small longitudinal incision does not damage
the fibers. The condition of the fibers of the RUL is assessed by pulling the distal
remnant with forceps to determine whether it can be sutured.[6]
[7] If there is severe degeneration or damage at the RUL, or the fibers are weak, the
ligament will be inelastic and easily disrupted. Reattachment of the TFCC using an
ECU half-slip is suitable in such cases.
The fovea of the ulna is débrided and scar tissue is removed until bleeding bone is
visible. A bone tunnel is made with a 2.5-mm diameter drill from the center of the
fovea to the ulnar neck more proximally ([Fig. 7a,b]). The position of the bone tunnel at the fovea is made as close to the center of
the fovea as possible, which is an isometric point during forearm rotation. A distally
based ECU half-slip tendon is then harvested. A 5-mm horizontal incision is made in
the floor of the ECU sheath at the ulnocarpal joint level. A curved mosquito forceps
is inserted into the peripheral unstable edge of the TFCC and then passed through
the horizontal ECU sheath incision. The half-slip tendon is then passed through the
edge of the TFCC and sutured to it ([Fig. 8a,b]). The ECU half-slip is then passed through the foveal bone tunnel to exit the medial
cortex of the ulna using a 4–0 nylon looped stitch. A small bone peg is then harvested
from the cortex of the ulna or radius and is inserted to the bone tunnel ([Fig. 9a,b]). The ECU half-slip is then anchored to the ulnar fovea with a small titanium interference
screw ([Fig. 10]). The capsule and ECU sheath are closed with mattress sutures.
Fig. 7a,b (a) A 0.9 mm guide wire in inserted to the center of the fovea. (b) A bone tunnel is created using a 2.5-mm cannulated drill.
Fig. 8a,b Illustration (a) and intraoperative view (b) of first step of reattachment of the TFCC. The distally based half-slip of the ECU
is introduced into the ulnar edge of the TFCC to the ulnar fovea.
Fig. 9a,b The avulsed TFCC is sutured to the ECU half-slip at the fovea. The half-slip of the
ECU is passed through a 2.5-mm bone tunnel to the proximal ulnar cortex ([a] illustration; [b] intraoperative findings). A small bone peg is already inserted to the bone tunnel
at the fovea before an interference screw is inserted.
Fig. 10a,b (a) Schematic of the final step of the reattachment of the TFCC. (b) A small interference screw is inserted into the fovea to anchor the ECU strip.
When the TFCC is reattached successfully ([Fig. 11]), there should be no DRUJ instability upon testing using a DRUJ ballottement test.
Pronation-supination range is usually full, since the TFCC is anchored to the center
of the fovea, where the center of forearm rotation passes. After reattaching the TFCC,
we prefer to evaluate the condition of the TFC arthroscopically. Tension of the central
area of the TFC is increased, which restores the trampoline effect.
Fig. 11 Immediate postoperative radiograph of the reconstruction. Note the interference screw
in the center of the fovea.
The patient is immobilized in a long-arm cast for 2 weeks followed by 3 weeks of a
short-arm cast. After removal of the cast at 5 weeks after the surgery, active ROM
exercise begins. Seven weeks after the operation, passive ROM exercise by an occupational
therapist may be needed, if there is a loss of pronation-supination range. Usually,
at 8 to 9 weeks after the operation, full pronation-supination range is achieved;
then arm curl exercise begins with up to 3 kg weight. Three to 6 months after the
operation, the weight may be increased to 5–10 kg. The patient may be back to preinjury
sports activity level 9 months after the surgery.
Results
Preoperatively, 2 patients had mild occasional pain, 16 patients had moderate (in
motion or twisting) pain, and 6 patients (7 wrists) had severe consistent pain. Fifteen
patients complained of DRUJ laxity. There was no loss of pronosupination range or
wrist motion. On physical examination, all of the patients had a positive ulnocarpal
stress test and severe DRUJ instability without any endpoint, which corresponded to
complete avulsion of the fovea-attaching fibers of the RUL.
An arthrogram demonstrated a complete avulsion of the TFCC at the fovea in 21 wrists,
while there was no dye leakage in 4. An MRI demonstrated a high signal intensity at
the ulnar fovea area in all 25 wrists. DRUJ arthroscopy[24] was performed in 20 wrists, which included an avulsion of the RUL in 13, scar tissue
without any RUL fiber tension in 4, while no visualization of the fovea was possible
due to severe scar tissue formation in 3. Open exploration revealed a complete detachment
of the RUL in all wrists.
At final follow-up of average 3.1 years (range, 2–7 years), 20 patients (21 wrists)
had no pain, 3 had mild pain at rest (occasionally painful), and 1 patient had severe
consistent pain. VAS was decreased from average 7.9 to 1.2. Twenty-four wrists indicated
full pronosupination and full wrist flexion-extension, while one patient had a 30
degree loss of supination. The DRUJ was stable in 22 wrists, moderately unstable (at
least one end point either in dorsal or palmar) in 2 wrists, and severely unstable
(no end point in any direction) in 1 patient. There were 21 excellent, 2 good, 1 fair,
and 1 poor results, with our original DRUJ evaluating system ([Table 1]) for DRUJ disorders. Grip power was recovered to an average of 91% (83–104%) compared
with the intact side.
Discussion
Considering the three-dimensional structure of the TFCC and of the nearly vertical
orientation of the fovea attaching fibers of the RUL,[3]
[4]
[5] it is our opinion that the repaired or reconstructed RUL must be reattached to the
center of the fovea of the ulna, which is the isometric point of pronosupination,
to prevent any loss of forearm rotation while stabilizing the DRUJ. The direction
of the reattached /reconstructed fibers should be along the original fiber direction
as much as possible. In chronic situations the peripheral rim of the TFCC can be reattached
to the fovea with this technique, provided that the tissue is not too damaged or fragile
to hold sutures.[6]
In this paper we describe a technique for reconstruction of the avulsed RUL to the
ulnar fovea using a ECU half-slip tendon. This technique reproduces the vertical origin
of the TFCC at the fovea. Other tendon graft techniques require two bony tunnels (at
the sigmoid notch and ulnar head), whereas our technique is performed through a single
ulnar tunnel and is easier. The clinical outcomes of this technique have been encouraging
at a midterm follow up.
