This clinical study evaluated two signs that can indicate a complete release of the transverse carpal ligament (TCL) during carpal tunnel release surgery: the "fat pad" sign and the "little finger pulp" sign. The study reviewed 643 carpal tunnel release procedures performed using a short longitudinal incision. Both signs were observed during surgery to confirm full division of the TCL. Post-operatively, symptoms resolved in nearly all patients, with minimal complications. The signs were useful for ensuring complete TCL release through a small incision.

1. CLINICAL STUDIES
“FAT PAD” AND “LITTLE FINGER PULP”
SIGNS ARE GOOD INDICATORS OF PROPER
RELEASE OF CARPAL TUNNEL
Ignacio R. Proubasta, M.D. OBJECTIVE: The release of the transverse carpal ligament (TCL) for relief of carpal tun-
Hand Surgery Unit, nel syndrome has been a standard operative procedure since the early 1950s. Although
Orthopaedic Department,
Hospital Sant Pau,
complications are not common after the open surgical technique, a small but significant
Barcelona, Spain group of patients will have similar symptoms after surgery or will experience new symp-
toms in the postoperative period. Incomplete section of the TCL is the major cause of
Alberto Lluch, M.D., Ph.D. these complications. The authors have described two signs that confirm a complete
Institut Kaplan, release of the TCL, called the “fat pad” and “little finger pulp” signs.
Barcelona, Spain
METHODS: Between 2000 and 2003, we treated 643 hands in 611 patients (45 men
Claudia G. Lamas, M.D.
and 566 women; age range, 32–76 yr; mean age, 58.2 yr). All patients were examined
Hand Surgery Unit,
6 months after the procedure, with special attention given to the persistence or recur-
Orthopaedic Department, rence of symptoms. The presence of palmar scar pain, residual numbness, patient sat-
Hospital Sant Pau, isfaction, and time to return to work were also evaluated. A longitudinal incision (2 cm)
Barcelona, Spain
at the base of the palm was used to release the TCL. A good indicator that the distal
TCL has been released is the visualization of a fatty tissue (“fat pad” sign). This fatty tis-
Barbara T. Oller, M.D.
sue is always present underneath the most distal fibers of the TCL, covering the sensory
Hand Surgery Unit,
Orthopaedic Department, digital branches of the median nerve. To confirm the complete release of the proximal
Hospital Sant Pau, fibers of the TCL, we should be able to introduce the little finger pulp in a proximal
Barcelona, Spain direction underneath the distal flexion crease of the wrist (“little finger pulp” sign).
When both signs are confirmed, we can be certain that the TCL is completely released.
Joan P. Itarte, M.D.
Hand Surgery Unit,
RESULTS: Night pain disappeared immediately after surgery in all patients except three.
Orthopaedic Department, There were seven complications (1%) not related to the palmar scar and 10 complica-
Hospital Sant Pau, tions (1.5%) related to it. However, all of these complications disappeared an average
Barcelona, Spain
of 3 months postoperatively. Patient satisfaction was 100%, and the mean time to return
Reprint requests:
to work and full activity was 22 days (range, 14–36 d).
Ignacio R. Proubasta, M.D., CONCLUSION: Two surgical observations that are reliable to confirm a complete release
Servicio de Cirugía Ortopédica y
Traumatología,
of the TCL were described. The first, called the “fat pad” sign, is useful to determine
Hospital Sant Pau, whether or not the distal end of the TCL has been adequately released, whereas the
Barcelona, Spain “little finger pulp” sign indicates whether or not the proximal end of the TCL has been
Email: iproubasta@hsp.santpau.es
fully divided.
Received, September 26, 2006. KEY WORDS: Carpal tunnel, Complications, Median nerve
Accepted, May 23, 2007.
Neurosurgery 61:810–814, 2007 DOI: 10.1227/01.NEU.0000280075.82080.A8 www.neurosurgery-online.com
S
ince it was first described by Sir James Paget (26) in 1854, first release of the TCL for median nerve compression was per-
carpal tunnel syndrome (CTS) has been the best under- formed by Herbert Galloway and Andrew McKinnon in
stood and most common of peripheral compression neu- Winnipeg, Canada, in 1924, on a patient with a posttraumatic
ropathies. In 1913, Pierre Marie and Charles Foix (24) recom- neuropathy (1). The wide recognition of spontaneous CTS has
mended decompression of the median nerve by sectioning the only been as recent as the early 1950s, largely through the writ-
transverse carpal ligament (TCL), but it was not until 1929 that ings of George Phalen (5). In 1951, Phalen described his tech-
the first surgical decompression was performed by Sir James nique using a transverse incision at the distal wrist crease, with
Learmonth on a patient with posttraumatic nerve compression proximal and distal extension as needed. However, it was not
(17). However, a review of the Mayo Clinic indicates that the until the 1970s, with the work of Taleisnik (36) and Lluch (20),
810 | VOLUME 61 | NUMBER 4 | OCTOBER 2007 www.neurosurgery-online.com

2. GOOD INDICATORS OF PROPER RELEASE OF THE CARPAL TUNNEL
that the longitudinal incision along the line of the ring finger
became the recommended approach.
The most common complication after endoscopic or open
carpal tunnel release is the incomplete release of the TCL (2, 3,
5, 6, 9–11, 13, 14, 16, 19, 22, 30, 35, 37, 38). When this occurs, the
preoperative symptoms usually persist or recur shortly after
the initial decompression. Incomplete division of the TCL is
avoidable by using a large longitudinal incision crossing the
wrist flexion creases, which allows adequate visualization of
the proximal and distal boundaries of the TCL. However, when
a short palmar incision is used (4, 7, 18, 33), it is difficult to
visualize the entire TCL and, as a consequence, incomplete
release of the TCL may occur.
This article discusses two surgical observations that are reli- FIGURE 2. Photograph illustrating the “fat pad” sign
able to confirm a complete release of the TCL. The first, called (arrows).
the “fat pad” sign, is useful to determine whether or not the
distal end of the TCL has been adequately released, whereas edge of the TCL, the median nerve was protected during ligament
the “little finger pulp” sign indicates whether or not the prox- division. A good indicator that the distal TCL has been released is the
imal end of the TCL has been fully divided. visualization of a fatty tissue after the Mac Donald dissector was
removed. This fatty tissue is always present underneath the most dis-
MATERIALS AND METHODS tal fibers of the TCL, covering the sensory digital branches of the
median nerve (Fig. 2). The proximal edge of the TCL is then divided.
A retrospective review was conducted on all patients treated for The proximal fibers of the TCL blend imperceptibly with the distal
CTS with a short palmar incision. Between 2000 and 2003, we treated forearm fascia, which can be
643 hands in 611 patients (45 men, 566 women; age range, 32–76 yr; divided up to 1 cm proximal to
mean age, 58.2 yr). The surgical procedure was identical in all cases. All the skin incision. To confirm the
patients were examined 6 months after the procedure, with special complete release of the proximal
attention given to persistence or recurrence of symptoms. The presence fibers of the TCL, we should be
of palmar scar pain, residual numbness, patient satisfaction, and time able to introduce the little finger
to return to work were also evaluated. pulp in a proximal direction
underneath the distal flexion
Technique crease of the wrist (Fig. 3). We
call this maneuver the “little fin-
All procedures were performed under regional block anesthesia with FIGURE 3. Photograph illustrat-
ger pulp” sign (21). When both
a tourniquet placed on the proximal arm. A longitudinal incision at the ing the “Little finger pulp” sign.
signs are confirmed, we can be
base of the palm was used. The incision was made in line with the lon-
certain that the TCL is com-
gitudinal axis of the flexed ring finger. The intersection of this longitu-
pletely released. The skin is approximated with interrupted 5–0
dinal line with the Kaplan line (i.e., a line parallel to the ulnar aspect of
monofilament sutures, and an antebrachial plaster cast is applied with
the extended thumb) marked the
the wrist in slight extension. Finger exercises are encouraged after sur-
distal extent of the incision.
gery. The plaster and sutures are removed 2 weeks after surgery.
Proximally, the incision ended
just distal to the distal wrist flex-
ion crease (Fig. 1). The subcuta- RESULTS
neous tissue was divided until
the TCL could be visualized. The Night pain disappeared immediately after surgery in all
flexor retinaculum was divided patients but three. There were no major complications related
on its ulnar border next to the to neural, vascular, or tendon damage. There were seven com-
hook of the hamate bone. When plications not related to the palmar scar (Group 1) and 10 com-
using this short skin incision, it is plications related to it (Group 2). In Group 1, three patients
important to have the surgical (0.5%) with transient postoperative hand numbness in the
assistant retracting on the skin median nerve distribution, three patients (0.5%) with residual
edges both proximally and dis- hand pain similar in nature but milder in intensity to the pre-
tally to optimize the exposure. FIGURE 1. Photograph showing operative pain, and one patient (0.1%) with finger hypersensi-
With experience, good retraction, that the incision begins at the
and good lighting, the length of
tivity were observed. These seven complications account for 1%
intersection of Kaplan’s line and a of all cases. In Group 2, four patients (0.6%) complained of
the skin incision may be short- line drawn along the longitudinal
ened, thus reducing postopera- occasional scar tenderness and six (0.9%) complained of palmar
axis of the flexed ring finger until
tive pain and recovery time. 1 cm above of the distal flexor
scar pain, mainly to the touch. These 10 complaints correspond
Using a MacDonald dissector crease of the wrist. to an overall complication rate of 1.5%. All of these complica-
placed underneath the distal tions disappeared an average of 3 months postoperatively.
NEUROSURGERY VOLUME 61 | NUMBER 4 | OCTOBER 2007 | 811

3. PROUBASTA ET AL.
TABLE 1. Results of revision carpal tunnel release after previous open carpal tunnel release surgerya
No. of Intact parts Scar Medical Other No abnor-
Series (ref. no.) Fibrosis
interventions of the TCL tethering injury causes malities
Langloh and Linscheid, 1972 (16) 34 21 (62%) — — — — —
Conolly, 1978 (9) 35 9 (31%) 4 — 7 10 5
Kern et al., 1993 (13) 16 10 (62%) 4 — 1 1 —
Assmus, 1996 (2) 185 91 (49%) 58 — — — 36
Bagatur, 2002 (5) 26 23 (88%) — 1 — 2 —
Unglaub et al., 2005 (37) 38 26 (68%) 8 3 — — 1
Stütz et al., 2006 (35) 200 108 (54%) 46 17 12 4 13
Pülzl et al., 2006 (30) 48 16 (33%) 24 — 8 — —
Assmus et al., 2006 (3) 57 34 (60%) 15 — 3 — 5
Frick and Baumeister, 2006 (11) 63 38 (60%) 21 2 1 1 —
a
TCL, transverse carpal ligament.
Patient satisfaction was 100%, and the mean time period to pad of palmar fat found at the distal end of the TCL and con-
return to work and full activity was 22 days (14–36 d). stitutes a reliable indicator of the complete release of the distal
edge of TCL. This appreciation is the same one that we have
DISCUSSION been using for many years (21). In a comprehensive review of
the anatomy of the carpal tunnel by Skandalakis et al. (34), a
CTS is the best understood and most common of the periph- reference has been made to the specialized palmar fat related to
eral compression neuropathies and, therefore, the most fre- the superficial arterial palmar arch in an area noted as the “dis-
quent hand operation. The common surgical treatment for CTS tal zone,” which was later verified in radiological (25), endo-
in patients who have failed to improve with conservative meas- scopic (12), and surgical (32) studies. For this reason, when the
ures is open carpal tunnel release. Although the longitudinal distal edge of the retinaculum has been completely released,
division of the TCL consistently relieves symptoms in most the fat pad described appears. Our results support the results
patients, some may complain of persistence of symptoms after of most of these studies, as no permanent complications and
surgery due to an incomplete release of the TCL (2, 3, 5, 9, 11, very few transient complications were observed (15).
13, 16, 30, 35, 37) (Table 1). Some authors (8, 23) have stated that
common indications for reoperation include previous incom-
plete surgery and postoperative fibrosis causing recurrence of
CONCLUSION
symptoms. Although the standard longer incision that crosses This study has several limitations because there is no control
the wrist crease allows complete visualization of the TCL from group. However, we have been using this technique without
the forearm fascia proximal to the superficial palmar arch dis- any modifications since 1984, after it was proposed by the sen-
tally, many experienced hand surgeons successfully use shorter ior author (AL), assuring a complete release of the TCL and
longitudinal incisions that do not cross the wrist crease to min- providing immediate and permanent relief of median nerve
imize scar tenderness, scar retraction, and injury to the thenar compression at the carpal tunnel.
sensory branch of the median nerve.
The “fat pad” and “little finger pulp” signs described in this
article have been helpful in confirming complete division of the
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NEUROSURGERY VOLUME 61 | NUMBER 4 | OCTOBER 2007 | 813

5. PROUBASTA ET AL.
T his article by Proubasta et al. introduces neurosurgeons to widely
known signs that are commonly used by hand surgeons when
they perform carpal tunnel release surgery. For more than a decade,
decompression. A blunt ball tip dissector could also be used instead
of a little finger.
I have applied them routinely in my own practice and have found Robert J. Spinner
them useful in ensuring adequate proximal and distal median nerve Rochester, Minnesota
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