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39
Endoscopic Carpal Tunnel Release: Agee Technique
Emran Sheikh
Department of Orthopedics and Plastic Surgery, Rothman Institute, Thomas Jefferson University,Philadelphia,
Pennsylvania, U.S.A.
Ednan Sheikh
Department of General Surgery, New York Presbyterian Hospital/Weill Cornell Medical Center, New York,
New York, U.S.A.
VirakTan
Department of Orthopedics, The New Jersey Medical School, University of Medicine and Dentistry of New Jersey,
Newark, New Jersey, U.S.A.
&
INTRODUCTION
Carpal tunnel syndrome (CTS), or median nerve compression at
the wrist, is the most common peripheral compressive neuropathy of the upper extremity with an overall prevalence of
1% to 5% in the United States (1–3). Prevalence estimates for the
industrial population range as high as 15% (4–6), whereas the
annual incidence of CTS is 1.0 to 3.46 per 1000 person years in
the general population (6–9). CTS is most common in middleage, occurring more often in women than men (10,11). Increased
body mass index has also shown to be correlated with CTS
risk (12).
At the wrist, the transverse carpal ligament (TCL) extends
across the volar aspect of the carpus to create aspace termed the
carpal tunnel or carpal canal. Normal anatomical structures
traveling through the carpal tunnel include nine digital flexor
tendons and the median nerve. As pressure increases within the
carpal tunnel, the median nerve is moreprone to compression
than the tendons (9,13). This pressureincrease has avariety of
etiologies, including positional variations (wrist extension or
flexion) (3), hamate hook variations (14), and space-occupying
lesions. Proximal ne rvecompression,general health issues,
and comorbidities may make the median nerve more prone to
increases in carpal tunnel pressure. Double crush phenomenon
etiologies include, thoracic outletcompression,smoking,
and diabetes mellitus (15). At apressure threshold of 20 to
30 mmHg,epineurialblood flowtothe median nerveis
decreased (16). With prolonged and compromised blood flow,
carpal tunnel symptoms and pathology advances.
Work-related risk factors for carpal tunnel are not clear,
as there is literaturesupporting opposite conclusions. De Krom
et al.concluded that although activities with aflexed or
extendedwrist carryahigher risk of CTS,typingwas not
associated with an increased risk of CTS (3). Repetitive tasks
in the work industry arenot clearlyassociatedwith the
development CTS (12).Reportshaveshownthatthe meatpacking and poultry processing industries have the highest
rates followed by the garment and automobile assembly industries, whileclericalwor kers haveamuch lowerrate (6).
Although amyriad of conditions contribute to the nerve compression of CTS,the final symptomatologymay be similar:
paresthesias in the median nervedistribution, heavines sof
the hand and/or wrist, nocturnal awakening, and even, pain
and weakness. Sensory disturbances are often reversible and
result from earlycompression.Howev er,motor symptoms
andsigns mayheraldirreversibledamagefromadvanced
compression.Painisdue to direct physicaldamagetothe
nerve rather than early compression.
Advanced CTS with thenar wasting or intractable symptoms is addressedwithsurgicaldivisionofthe TCL,thus
reducing pressure on the median nerve (17,18). Learmonth is
credited with the first open carpal tunnel release (CTR) in 1929
and was later popularized by Phalen in the 1950s (19). Classically,CTR is performed by an open technique. In attempts to
reduce recovery time and risks such as pillar pain, modifications of the classic open CTR have centered on reducing
incision size. However,despite the smaller incisions, recovery
and risks were similar (20). Ameta-analysis of the literature by
Boeckstyn concluded that the risk of nerve injury to be 0.2% for
open CTR (21).
With theadventoffiberoptic technology, endoscopic
carpal tunnel release (ECTR) techniques weredeveloped as
minimally invasive procedures for dividing the TCL. Initially,
ECTRutilizedatwo-portaltechnique, whichhad ahigher
incidenceofcomplications at thedistalportal site (22,23).
In 1992, Agee et al. (24) reported on endoscopic release using
asingle-portal approach where the endoscope, light source,
and blade system are unified within the same instrument to
allow visualization of the TCL, thereby increasing the safety.
The focusofthis chapter is to discuss the Agee technique
for ECTR.
&
INDICATIONS
The generalindicationsfor surgical treatment(whether
endoscopic or open) for CTS are failed conservative management and advanced stage with thenar atrophy or weakness.
There are instanceswhen ECTR should notbecarried out,
suchasincases wheresynovectomyorbiopsy is needed.
Although data has shown some success for ECTR for recurrent
CTS after prior open release, this data is limited (25). Therefore,
revision CTR, regardless the primary mode of release (open
or endoscopic), may be best approached by an open release
because neurolysis of the median nerve may also be necessary
(26).Other relative contraindications forECTR include
calcified tendinosis, hamate hook fractures, andcongenital
anatomic anomalies.
&
CONSIDERATIONS FOR PREOPERATIVE
PLANNING
See discussion in Chapter 36.
&
SURGICAL TECHNIQUE
Astandard surgical setup for wrist procedureisused with
the patient supine and the arm abducted on ahand table. The
instruments (MicroAire Surgical Instruments, Charlottesville,
VA)are opened and assembled on asterile field (Figs. 1and 2).
Surgeryisusually performed with intravenous sedation and
local anesthetic under tourniquet. Care is taken to use the local
anesthetic for only cutaneous and subcutaneous injection at the
site of proximal wrist crease incision. Injection within the carpal
tunnel and deep into the antebrachial fascia is avoided because
it can lead to fogging of the camera lens and poor endoscopic
visualization.
After surgical markings and inflation of the tourniquet, a
transverse skin incision is made within the long axis of the ring
finger metacarpal (Fig. 3). The antebrachial fascia is divided in
transverse fashion. The distal margin of the fascia incision is
used for traction to allow initial blunt dissection between the
synovium and undersurface of the antebrachial fascia, permitting entry into the carpal tunnel. AHamate Finder is introduced
through the incision into the carpal canal, deep into the TCL and
radial to the hook of the hamate (Fig. 4). Gentle serial passes
with the Hamate Finders can be done to prepare the path. The
undersurface of the TCL is then cleared of synovial tissue with
the Synovium Elevator.This step is performed blind but guided
by knowledge of surgical anatomy andtactile feedback.
Adequacyofdissectioncan be determined by feelingthe
“ridges” on the undersurface of the TCL. At this point, the
endoscope is inserted (Fig. 5).
The majority of times, theendoscopecan be inserted
without resistance. If resistance is met, this may be addressed
with further dissection with the Synovium Elevator and serial
insertionofthe Hamate Finders. Confirmationofadequate
exposureofthe undersurface of the TCL is made with direct
endoscopicvisualization. Light intensityisset to allow
discrimination of the transverse ridges of the deep surface of
theTCL. Inadequate or toomuch brightness will lead to
suboptimal ability to discern any crossing structures,including
anomaliesofthe motorbranchofthe median nerve. The
endoscope canbeuse dtobluntly push tissueawayfor
better visualization.
Several options are available to create aclear path before
incision of the TCL. Slight rotation of the endoscope in an ulnar
direction can increasethe distance from the median nerve or
anomalous motorbranch. Cautious bluntdissectionwith
the endoscope by scraping away the synovium may increase
visualization. Simple removal and reinsertion of the endoscope
whileprovi ding tractiononthe distal antebrachial fascial
edge at thesiteofincisionmay allowclearance of tissues
(fat and synovium) from the endoscope line of sight. Finally,
the subfascial path at the level of the antebrachial fascia should
be well dissected to allow the Synovium Elevator to be inserted
deep into thefasciaatthe levelofthe incision.Deliberate
dissection at the undersurface of the fascia and TCL is necessary
to allow optimal exposure.
Once the TCL undersurface is well-exposed (Fig. 6), the
trigger on the Handpiece is pulled to deploy the blade at the
end of the Disposable Blade Assembly.The distal margin of
the ligament is divided first which allows the surgeon to assess
the thickness of the TCL and to verify the distal extent of the
true carpalligament. Thecross-sectionisoften obviousin
A
B
C
D
E
FIGURE 1 MicroAire instruments for Agee endoscopic carpal tunnel
release technique. (A) Handpiece, (B) standard endoscope, (C) Disposable Blade Assembly, (D) Hamate Finders, and (E) Synovium Elevator.
Source:Courtesy of Virak Tan, MD.
FIGURE 2 Assembly of handpiece,endoscope, and disposable blade.
Source:Courtesy of Virak Tan, MD.
Incision
Hook of hamate
PL
Kaplan's line
FIGURE 3 Surgical markings for Agee technique of endoscopic carpal
tunnel release. Source:Courtesy of Virak Tan, MD.
306
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Sheikh et al.
defining the distal TCL. Thereafter,serial, distal to proximal,
division of the ligament is carried out. The surgeon’s contralateral hand is used to position the wrist and provide external
counter-pressuretojuxtapose the endoscope blade with the
undersurface of the TCL. The TCL is divided by engaging the
blade on the undersurface of the ligament and slowly withdrawing it proximally.Complete division of the ligament is
confirmed with protruding fat or visualization of the palmaris
brevis muscle (Fig. 7). Division of the muscle is not needed as it
adds to postoperative pain and prolongs recovery.Engaging the
blade too deeply may result in injury to the palmaris brevis,
intramuscular vessels, cutaneous nerves within the palm, or
even the ulnar neurovascular bundle. After endoscope removal,
another centimeter of antebrachial fascia can divided proximal
to the incision under direct visualization with tenotomy scisscors, as warranted. Often this proximal antebrachial fascia can
result in persistent carpal tunnel symptoms, especially after
minimally invasive or short-incision open CTR.
At the end of the procedure, the tourniquet is deflated. Any
bleeding can be controlled with manual pressureapplied to
the area of surgery for five minutes while elevating the hand
above the level of the heart. Remaining cutaneous bleeding at
the incision site may be controlled with bipolar electrocautery.
The wound is irrigated and bupivicaine injected aroundthe
incision. Skin is closed in asimple, single-layeredfashion. Asoft
dressing is applied.
Postoperatively,the patient is encouraged to use the hand
immediately for light tasks such as handling paper or holding a
cup. The surgical dressing is removed after twenty-four hours.
At two weeks, the patient may carry up to ten pounds. The
patient is allowed to return to work between 10 and 14 days
with the above restrictions. Full, unrestricted activity is allowed
at four weeks and the patient is also instructed on scar massage.
FIGURE 4 Introduction of the Hamate Finder into the carpal canal,
stayingdeep into the transversecarpal ligament and radialtothe
hamate. Source:Courtesy of Virak Tan, MD.
FIGURE 5 Insertion of the assembled endoscope into the carpal tunnel.
Source:Courtesy of Virak Tan, MD.
FIGURE 6 Endoscopic visualization of the undersurface of the transverse carpal ligament. Source:Courtesy of Virak Tan, MD.
FIGURE 7 Endoscopicvisualization after division of the TCL, showing
agap between the two ends. The subcutaneousfat and palmaris brevis
muscle can be seen superficial to the divided TCL. Abbreviation:TCL,
tranverse carpal ligament. Source:Courtesy of Virak Tan, MD.
Endoscopic Carpal Tunnel Release: Agee Technique
&
307
&
COMPLICATIONS AND THEIR MANAGEMENT
As with any arthroscopic or endoscopic procedure, ECTR is
vitally dependent on the surgeon’s ability to visualize structures
through the scope. Any impediment in visualization can render
the procedureimpossible to safely complete without conversion
to an open technique. Variouscausesexist for inadequate
endoscopic visualization: faulty camera hardware, inadequate
light source, fogging of the lens, inadequate exsanguination
of tissues, andanomalous anatomy. Progressing with the
procedure with less than optimal visualization is unsafe and
increases the risk of complications and incomplete division of
the TCL.Ifthe endoscopic procedure cannot be performed
safely,itshould be abandoned and converted to an open CTR.
When converting to an open procedure, the transverse skin
incision should be incorporated into azig-zag incision across
the wrist flexion crease to decrease the risk of scar contracture
postoperatively.Alternatively,askin bridge can be left between
the endoscopic and open carpal tunnel incisions. Other reasons
for conversiontoanopen technique include uncontrollable
bleeding after tourniquet deflation, intraoperative tendon or
nerve laceration, inability to confirm complete division of the
TCL, unclear or abnormal anatomy,orunexpected discovery
of carpal tunnel pathology (mass, extensive synovitis, etc.). Any
known intraoperative complication should be addressed during
the open procedure.
&
OUTCOMES
Nocturnal awakeningand provocationorexacerbation of
parasthesias shouldresolve almost immediately.Subjective
numbness of digits may take as along as several months to
resolve depending on degree of nerve injury preoperatively.
Similarly,thenar wasting or weakness may also take several
months to reachfinal re cove ry levels.Althoughsensory
recovery is usually near complete, muscle strength is dependent
on degree and length of neuromuscular injury preoperatively.
In their multi-center trial, Agee et al. (24) reportedon122
patients (147 hands) who were randomized to the endoscopic
( n Z 82 hands)versus open ( n Z 65 hands) techniques.For
patients in theECTRgroupwithone affected hand,the
median time for return to work was 21.5 days less than that
for the open carpal tunnel group. Twopatients who had ECTR
required reoperation; one had incomplete release of the TCL.
Twopatients in the device groupalso experienced transient
ulnar neurapraxia.
In 2002, Trumbleetal. (27) publishedaprospective,
randomized, multicenter center study comparing open CTR to
ECTR using theAgeetechnique. The openmethodwas
performed in 95 hands in 72 patients, and the Agee method
was performed in 97 hands in 75 patients. The authors found
that during the first three months after surgery,the patients
treated with theAgeemethod hadbetter CarpalTunnel
Syndrome Symptom Severity Scores, Carpal Tu nnel Syndrome
Functional Status Scores,and subjectivesatisfaction scores.
These patients also hadsignificantly greatergripstrength,
pinch strength, and hand dexterity.Patients who had open
CTR had more scar tenderness and longer time offfrom work
during the same time frame. In this series, the rate of complications and cost of surgery between the two groups werenot
significantly different.
Schonauer,Varma and Belcher (28) reported on 565 consecutive ECTR by asingle surgeon using amodified Agee technique.
There was 4.4% rate of conversion to the open technique because
of inadequate visualization, tight carpal canal,tourniquet
failure,and aberrant anatomy.Postoperatively,immediate
symptomatic reliefwas reported in 99.5%.There were25
complications includingpillar pain (8 wrists), digital
neuropraxia ( n Z 6), median nerve contusion ( n Z 3), incomplete
division of the TCL ( n Z 3), superficial infection ( n Z 3), reflex
sympathetic dystrophy(n Z 1), and scar tenderness ( n Z 1). The
authors concluded that their modified Agee technique can result
in good outcome but also recommended caution in performing
ECTR in patients who may have small wrists because of the risk
of median nerve contusion.
&
SUMMARY
The Agee ECTR technique represents asingle-portal, minimally
invasive proceduretotreat patients with median nerve compression at the wrist who meet the criteria for surgery.General
advantages of this technique over open CTR include:
&
less scar tenderness
&
decreased pillar pain
&
faster recovery of pinch and grip strength, and
&
earlier return to work and daily activities.
Moreover,the Agee technique has the advantage of being
asingle incision technique that utilizes ablade system that
readily attaches to the standard endoscopic equipment that is
widely available in most medical centers. However,asinany
surgical andespecially endoscopic procedure, safety and
successare dependent upon patient selection, thorough
knowledgeofthe surface and surgicalanatomy,adequate
training, and familiarity with the use and capabilities of the
instrumentation. Surgeons whoare notfamiliarizedwith
endoscopic equipment and technique may give rise to major
iatrogeniccomplications.
&
REFERENCES
1. Concannon MJ, Gainor B, Petroski GF,Puckett CL. The predictive
value of electrodiagnostic studies in carpal tunnel syndrome. Plast
Reconstr Surg 1997; 100:1452–8.
2. Atroshi I, Gummesson C, Johnsson R, et al. Prevalence of carpal
tunnel syndrome in ageneral population.JAMA 1999; 282:153–8.
3. deKromMC, Kester AD, Knipschild PG, et al. Risk factors for
carpal tunnel syndrome. Am JEpidemiol 1990; 132:1102–10.
4. Franzblau A, We rner RA, Va lle J, et al. Wo rkplace surveillance for
carpal tunnel syndrome: acomparison of methods. JOccup
Rehabil 1993; 3:1–14.
5. Homan MM, Franzblau A, We rner RA, et al. Agreement between
symptom surveys, physical examination procedures and electrodiagnostic findings for carpal tunnel syndrome. Scand JWork
Environ Health 1999; 25:115–24.
6. Franklin GM, Haug J, Heyer N, et al. Occupational carpal tunnel
syndrome in Wa shington State, 1984–1988. Am JPublic Health
1991; 81:741–6.
7. Nordstrom DL, DeStefano F, Vierkant RA, et al. Incidence of
diagnosed carpal tunnel syndromeinageneral population.
Epidemiology1998; 9:342–5.
8. Stevens JC, Sun S, Beard CM, et al. Carpal tunnel syndrome in
Rochester, Minnesota, 1961–1980. Neurology 1988; 38:134–8.
9. Mondelli M, Giannini F, Giacchi M. Carpal tunnel syndrome
incidence in ageneral population. Neurology 2002; 58:289–94.
10. Mondelli M, Aprile I, Ballerini M, et al. Sex differences in carpal
tunnel syndrome: comparison of surgical and non-surgical populations. Eur JNeurol 2005; 12(12):976–83.
11.Moghtaderi A, Izadi S, Sharafadinzadeh N. An evaluation of
gender,body mass index, wrist circumference and wrist ratio as
independent risk factors for carpal tunnel syndrome. Acta Neurol
Scand 2005; 112(6):375–9.
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12. Nathan P, Istvan J, Meadows K. Alongitudinal study of predictors
of research-defined carpal tunnel syndrome in industrial workers:
findings at 17 years. JHand Surg [Br] 2005; 30(6):593–8.
13. Lim J, Cho S, Han TR ,etal. Dose-responsiveness of electrophysiologic change in anew model of acute carpal tunnel syndrome. Clin
Orthop 2004; 427:120–6.
14. Chow JCY,Weiss MA, Gu Y. Anatomic variations of the hook of
hamate and the relationship to carpal tunnel syndrome. JHand
Surg [Am] 2005; 30(6):1242–7.
15. Werner RA, Franzblau A, Gell N, et al. Incidence of carpal tunnel
syndrome among automobile assembly workers and assessmentof
risk factors. JOccup Environ Med 2005; 47(10):1044–50.
16. Michelsen H, Posner MA. Medical history of carpal tunnel
syndrome. Hand Clin 2002; 18(2):257–68.
17. Okutsu I, Hamanak I, Chiyokura Y, et al. Intraneural median nerve
pressure in carpal tunnel syndrome. JHand Surg [Br] 2001;
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18. Sanz J, Lizaur A, Sanchez Del Campo F. Postoperative changes of
carpal canal pressureincarpal tunnel syndrome: aprospective
study with follow-up of 1year.JHand Surg [Br] 2005; 30(6):611–4.
19. Phalen GS, Gardner WJ ,LaLonde AA. Neuropathy of the median
nerve due to compression beneath the carpal ligament. JBone Joint
Surg Am 1950; 32:109–12.
20. Tzaan W, Lui T, Lee S. Midpalmar accurate incision for carpal
tunnel release. Chang Gung Med J2005; 28(2):97–103.
21. BoeckstynsMEH, Sorensen AI. Does endoscopic carpal tunnel
release have ahigher rate of complications than open carpal
tunnel release? JHand Surg[Br] 1999; 24:9–15.
22. Nath RK, MackinnonSE, Weeks PM .Ulnar nerve transection as a
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report. JHand Surg [Am] 1993; 18:896–8.
23. Murphy RX, Jennings JF,Wukich DK. Major neurovascular complications of endoscopic carpal tunnel release. JHand Surg [Am]
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24. Agee JM, McCarroll HR, Jr., Tortosa RD, et al. Endoscopic release of
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25. Teoh LC, TanPL. Endoscopic carpal tunnel release for recurrent
carpal tunnel syndrome after previous open release. Hand Surg
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26. Mackinnon SE, McCabe S, Murray JF,etal. Internal neurolysis fails
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27. Trumble TE,Diao E, Abrams R, et al. Single-portal endoscopic
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Endoscopic Carpal Tunnel Release: Agee Technique
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309
Part VIII: Tendons and Soft Tissues
40
Percutaneous Trigger Finger Release
Min Jong Park
Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine,
Seoul, Korea
&
INTRODUCTION
Trigger finger is one of the most common problems seen in
the clinical practice of orthopedic surgery. It is caused by a
disproportion between the flexor tendons and their sheath,
and it presents with painful triggering or locking of the affected
digit during finger motion. The most common form of trigger
finger is the primary type, which is found most frequently
among middle-aged women, two to six times more commonly
than it is observed in men. The most commonly affected digit is
the thumb, followed by the long, ring, index, and little fingers.
The involvement of several fingers is not unusual. Secondary
trigger finger can be found in patients with diabetes, gout, renal
disease, and rheumatoid diseases, and it is associated with a
worse prognosis after conservative management.
The main pathology of entrapment is mechanical impingement of the flexor tendons as they pass through the narrowed
first annular (A1) pulley at the level of the metacarpal head.
Thus, the goal of treatment is to provide a painless, smooth, and
full range of finger motion. As a conservative method of
treatment, steroid injection has been commonly recommended
(1). Although this treatment is simple and has low morbidity, it
may be associated with a high failure rate, and repeated
injections are usually required because of a high recurrence
rate. In reported series of injection therapy, the success rate
varied from 37.5% to 84% (1–4). This therapy appears to be less
useful in more advanced cases. Rhoades et al. observed that
patients with symptoms of less than four months’ duration
achieved a success rate of 93% after steroid injection, while
those with symptoms of greater than four months achieved a
41% success rate (5). Newport et al. reported that patients who
had symptoms for more than six months were more likely to
require surgery (4).
When conservative treatments fail to relieve the symptoms,
surgical release of the A1 pulley by open technique is generally
recommended (6,7). The most attractive aspect of operative
management may be its ability to provide a permanent cure.
Open trigger finger release is considered a simple and reliable
procedure, but entails making a 1 to 2 cm incision in the palm
directly the A1 pulley. The subcutaneous tissue is dissected
bluntly off the pulley, which is then released under direct
visualization. Successful results have been reported with this
technique, but it is not without complications. These include
infection, digital nerve injury, joint stiffness, hand weakness,
scar tenderness, and bowstringing of the flexor tendons (8–10).
Since Lorthioir described a technique of percutaneous
release of the A1 pulley using a fine tenotome in 1958 (11),
several techniques for percutaneous release using a variety of
cutting instruments have been described as simple office
procedures (12–21). Percutaneous release, if it is equally
effective and safe, would avoid the time and expense of an
open surgical procedure. It also has the advantage of avoiding
complications that are closely related with the open procedure,
such as infection, incisional pain, hypertrophic scarring, and
delayed use of the hand, which may be due to the development
of reflex sympathetic dystrophy or stiffness.
&
INDICATIONS
The clinical course of trigger finger is generally divided into
four stages as follows, depending on the degree of the tendon
catching during the motion of the affected digit (15,19)
&
Grade 1: No triggering, only uneven movements during
finger motion
&
Grade 2: Triggering, actively correctable
&
Grade 3: Triggering, passively correctable by the other hand
&
Grade 4: Locked and uncorrectable. Patients who have a
locked trigger digit can present either with a fixed flexion
contracture at the proximal interphalangeal (PIP) joint or
with an inability to fully flex the affected digit from an
extended position.
Percutaneous release of the A1 pulley is mainly indicated
when the symptoms fail to be relieved by conservative treatment, including steroid injections. As the procedure can be
simply performed in the office under local anesthesia without
specific preparations, it is relatively indicated as a first-line
treatment in patients with severe or longstanding symptoms,
who are more likely to require surgery.
In this author’s clinical practice, percutaneous technique is
recommended in those patients who have had symptoms for
more than four months, or have Grade 3 or 4 triggering at the
time of their initial presentation. Others find locked trigger
digits (i.e., Grade 4) as a contraindication to percutaneous
techniques because of a higher failure rate (22). Although the
percutaneous release of the locked digits seems to have a higher
failure rate than that of other trigger digits, it is believed that
locked trigger digits can be released safely and effectively by
percutaneous method if several technical points are considered,
which are discussed below.
Another issue with respect to indications of the percutaneous technique is whether it can be performed in children with
a trigger digit. Although some authors have reported successful
results (23), it should be performed cautiously for the following
reasons: (i) due to anxiety pediatric patients may not be able
to stay still and confirm complete release with just local
anesthesia, which risks safety during the procedure, (ii)if
general anesthesia is required, the patient will not be able
to actively move the digit intraoperatively to determine that
a complete release has been achieved, and (iii) almost all trigger
&
Park
312
phenomena in children occur at the thumb, which has the
increased risk of nerve injury due to the proximity of the
digital nerves to the A1 pulley. The potential for nerve injury
is significantly increased in children because of the small size of
their thumbs.
In patients with secondary triggering, such as tenosynovitis, percutaneous release is generally not recommended
because of unpredictable results.
&
CONSIDERATIONS FOR PREOPERATIVE PLANNING
Trigger digit can be diagnosed easily when “catching” is
described by patients during active finger motion. Additionally,
there is tenderness volarly over the A1 pulley at the metacarpal
head. At a more advanced stage, locking of the flexor tendons
in the A1 pulley develops, which results in an inability to fully
flex or passively extend the affected digit. It should be noted
that many patients, particularly with locked trigger digits,
can have painful secondary contractures at the PIP joint or at
the interphalangeal (IP) joint of the thumb. Although this is
considered secondary to reluctance of the patients to perform a
full range motion of the digits over time, it is frequently the
main cause of pain and discomfort. Due to stiffness at the PIP
joint and the absence of typical triggering, the patient or
examining physician often localizes the pathology incorrectly
at the PIP joint. In such a situation, the presence of a triggering
history before the development of locking would contribute in
making the correct diagnosis. When the triggering history is
unclear, tenderness at the metacarpal head should be checked.
Rarely, localized enlargement of the flexor digitorum profundus
can trigger at a stenotic A3 pulley and lead to persistence of
symptoms after release of the A1 pulley. Trigger digits in
patients with rheumatoid arthritis may be due to synovitis
along the flexor tendons and profundus entrapment at the
superficialis decussation.
If the percutaneous release is determined to be indicated
after the diagnosis is made, no imaging study is usually needed.
However, when the PIP joint is unusually stiff and painful, plain
X rays may be required to rule out articular problems. If fixed
contracture of PIP is considered secondary to advanced stage of
triggering, percutaneous release can still be tried as a first-line
treatment. If the PIP contracture is resistant to manual
stretching after percutaneous release, it may require surgical
release. However, such case is very rare unless the PIP has intraarticular problems.
&
SURGICAL TECHNIQUE
Since Eastwood et al. described the percutaneous method using
a hypodermic needle to section the A1 pulley (15), the hypodermic needle has been used most frequently among a variety
of cutting instruments. Following is the brief description of this
hypodermic needle procedure.
The A1 pulley is palpated directly over the metacarpal
head in the palm, and the skin and flexor tendon sheath are
infiltrated with 1 to 2 mL of 1% lidocaine using a 27-gauge
needle. With the affected metacarpophalangeal joint held firmly
in hyperextension, a 19- or 21-gauge needle is placed percutaneously through the A1 pulley. Placement of the needle tip
within the flexor tendon is confirmed by asking the patient to
slightly flex the digit and observing movement of the hub of the
needle. The needle is then withdrawn slowly and rotated to
align the beveled edge along the longitudinal axis of the tendon.
A sawing motion is used to section the A1 pulley proximally
FIGURE 1 Percutaneous release of a long finger first annular (A1)
pulley using a hypodermic needle. The bevel of the needle is oriented
longitudinally with the tendon, and a sawing motion is used to section the
A1 pulley.
and distally to the site (Fig. 1). Disappearance of a grating
sensation indicates complete sectioning of the A1 pulley.
My experience with the Eastwood technique demonstrated
that it was not always successful because the needle bents easily
and did not cut well when the A1 pulley was thickened and
stenotic. It was also not easy to handle the needle because of the
small hub and there was a steep learning curve. As a modified
technique, a specially designed knife (HAKI knife; BK Meditech
Inc., Seoul, Korea) has been developed (17), which has a hookshaped end with a blade only on the inner side and a pointed
end to facilitate its insertion into the skin without making an
incision. The depth of the blade which is for section of the A1
pulley is less than 1 mm to prevent injury to the flexor tendons
(Fig. 2). It is designed to cut the transverse fibers of the A1
pulley longitudinally from a proximal to distal direction after it
is inserted distal to the A1 pulley (Fig. 3).
The procedure is generally performed in the outpatient
setting under local anesthesia. The patient is placed in a supine
position with the affected hand on the examination table. The
surgeon sits on the distal side of the affected hand. The point
of triggering at the A1 pulley is located by palpation (Fig. 4).
FIGURE 2 A specially designed knife (HAKI knife; BK Meditech Inc.,
Seoul, Korea) for percutaneous first annular pulley release. It has a hookshaped end with a blade on the inner side and a pointed end to facilitate
its insertion into the skin.
FIGURE 3 The technique offirst annular (A1) pulley release using HAKI
knife. After the knife is introduced distally to the pulley, the blade is
advanced to its proximal margin and hooked over the border. The A1
pulley is divided by moving the knife from a proximal to distal direction.
&
Percutaneous Trigger Finger Release
FIGURE 5 One percent of lidocaine is infiltrated into the skin, subcutaneous tissue, and tendon sheath using a 27-gauge needle inserted
over the point of knife entry.
313
The skin of the palm is thoroughly cleaned and 1 mL of 1%
lidocaine without epinephrine is infiltrated into the skin and
subcutaneous tissue by means of a needle inserted directly over
the point of knife entry (Fig. 5).
The relationship of the surface anatomy of the palm to the
A1 pulley needs to be reviewed in order to identify the exact
point of knife entry. Several studies (11,24) have demonstrated
that the proximal edge of the A1 pulley coincides almost exactly
with the proximal palmar crease in the index finger, halfway
between the proximal and distal palmar creases in the middle
finger, the distal palmar crease in the ring and little fingers. In
the thumb, metacarpophalangeal crease indicates the middle of
the A1 pulley (Fig. 6). The knife is introduced a few millimeters
distal to the A1 pulley, which coincides with the point
approximately 1.5 cm distal to the landmarks that indicate the
proximal edge of the A1 pulley. The precise locations of the
knife entry are important for successful release. An incomplete
FIGURE 4 Percutaneous first annular (A1) pulley release of a ring
finger in a patient with longstanding triggering. The point of triggering at
the A1 pulley is palpated after skin preparation.
FIGURE 6 Surface anatomy of the palm to the first annular (A1) pulley.
The proximal edge of the A1 pulley coincides with the proximal palmar
crease in the index finger; halfway between the proximal and distal
palmar creases in the middle finger; at the distal palmar crease in the
ring and little fingers. In the thumb, metacarpophalangeal (palmodigital)
crease indicates the middle of the A1 pulley. The knife is introduced
1.5 cm distal to the landmarks that indicate the proximal edge of the A1
pulley (round dot). The precise locations of the knife entry are important
for successful release.