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quality mini C-arm, and MIS-specific devices and implants.
Although there is asteep initial learning curve, precise knowledge of the anatomy and surgical techniques will allow for safe
application of these procedures and faster recoveryfor patients.
&
REFERENCES
1. Lorgelly PK ,Dias JJ, Bradley MJ, Burke FD.Carpal tunnel syndrome,
the searchfor acost-effective surgical intervention:arandomised
controlled trial. Ann RColl Surg Eng 2005; 87(1):36–40.
2. Monaghan BA. Uses and abuses of wrist arthroscopy.Tech Hand
Up ExtremSurg 2006; 10(1):37–42.
3. Savoie FH,III, Whipple TL.The roleofarthroscopy in athletic
injuries of the wrist. Clin Sports Med 1996; 15(2):219–33.
4. Dailey SW,Palmer AK. The role of arthroscopy in the evaluation
and treatment of triangular fibrocartilage complex injuries in
athletes. Hand Clin 2000; 16(3):461–76.
5. Athwal GS, Bueno RA, Jr., Wo lfe SW.Radiation exposureinhand
surgery: mini versus standardC-arm. JHand Surg[Am] 2005;
30(6):1310–6.
6. Badman BL, Rill L, Butkovich B, Arreola M, Griend RA.
Radiation exposurewith use of the mini-C-arm for routine
orthopaedic imaging procedures. JBone Joint Surg [Am] 2005;
87(1):13–7.
7. Sinha S, Evans SJ, Arundell MK, Burke FD .Radiation protection
issues with the use of mini C-arm image intensifiers in surgery in
the upper limb. Optimisation of practice and the impact of new
regulations. JBone Joint Surg [Br] 2004; 86(3):333–6.
8. Brooks K, Capo J, Wa rburton M, Ta nV.Internal fixation of distal
radius fractures with novel intramedullary implants. Clin Orthop
Rel Res 2006; 445:42–50.
9. TanV,Capo J, Wa rburton M. Distal radius fixation with an intramedullarynail. Tech Hand Up Extrem Surg 2005; 9(4):195–201.
10. Orbay J. Intramedullary nailing of metacarpal shaft fractures. Te ch
Hand Up ExtremSurg 2005; 9(2):69–73.
11.Nagle DJ. Endoscopic carpal tunnel release. Hand Clin 2002;
18(2):307–13.
12. Ha KI, Park MJ, Ha CW.Percutaneous release of trigger digits.
JBone Joint Surg [Br] 2001; 83(1):75–7.
13. Ve lla JC, Hartigan BJ, Stern PJ .Kaplan’s cardinal line. Hand Surg
[Am] 2006; 31(6):912–8.
14. Bain GI, Turnbull J, Charles MN, Roth JH, Richards RS. Percutaneous A1 pulley release: acadaveric study.JHand Surg [Am] 1995;
20(5):781–4.
15. Lorthioir J. Surgical treatment of trigger finger by asubcutaneous
method. JBone Joint Surg [Am] 1959; 40:793–5.
16. Pope DF,Wolfe SW.Safety and efficacy of percutaneous trigger
finger release. JHand Surg [Am] 1995; 20(2):280–3.
FIGURE 6 The mid-axial line of an index finger. The dorsal most points of the interphalangeal joint flexion creases
are marked with the finger flexed ( far left). The dots are connected, establishing the mid-axial line over the proximal
and distal phalanges(middle and far right). Source:Courtesy of Virak Tan, MD.
Dorsal
Volar
Cleland,s
ligament
ET
Bone
LB
Flexor
tendons
Digital a.
&n.
FIGURE7 Diagramofacross sectionofadigit. Themid-axial
approach ( open arrow)isdorsal to the digital neurovascular bundle.
Any surgical approachthat is in the arc dorsal to the mid-axial line
( dashed line)carries alow risk of injury to the digital arteries and nerves.
Abbreviations:ET, extensor tendon; LB, lateral band. Source:Courtesy
of Virak Tan, MD.
4
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Tan and Capo
Part II: Basic Techniques
2
Use of Suture Anchors in Hand Surgery
Aaron Daluiski
Department of Orthopedic Surgery, Hospital for Special Surgery and Weill Medical College of Cornell University,
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
In hand surgery,itisoften necessary to repair soft tissue to bone.
Prior to the advent of suture anchors, tissue such as capsule,
ligament, or tendon was attached to bone by directsuture to
periosteum, or use of bone tunnels with pullout sutures or
sutures tied over abone bridge. Although useful and costeffective, all of these techniques have acertain limitations and
do, at times, requirelonger or separate incisions and significantly more soft tissue dissection and stripping.
One of the traditional methods of soft tissue reattachment
to bone is suturing the soft tissue over abone bridge. This is
performed by creating two or three drill holes in the bone and
passing the soft tissue, such as aslip of tendon, or suture on
either side of the tunnel and tying it over the bone bridge.
If done through the same incision,the skin and soft tissue
dissection needs to be extended to gain adequate exposureof
the bony cortical surface. Alternatively,the bone bridge can be
at the far cortex, but this requires asecond incision (
Fig. 1 ).
Additionally,the use of the bone bridge is limited to the larger
bones of the hand and wrist because creating bone tunnels in
small bones carries substantial risks. It is possible to either make
the bone tunnels too small for the tendon to pass through, or to
make the holes in the bone too largerisking fracture of the
adjacent bone bridge that is necessary for fixation. These risks
increase as the size of the bone decreases.Furthermore, the
repair is oftenbulky,making subsequent skin closure
moredifficult.
When the size of the bone does not allow for bone tunnels,
abutton can be used as asubstitute to the bone bridge to
provide fixation. The use of this technique requires the use of a
pullout smooth suture or wire that is placed in the soft tissue
in anon-locking fashion. The two ends of the sutureare then
passed through (or on either side of) the bone, out of the skin
and tied over apadded button (
Fig. 2 ). This externally placed
button diffuses the pressureacross the underlying soft tissue
but may still cause skin irritation or breakdown and, in rare
cases,damagethe superficial nerves in the region.After
appropriate soft tissue-to-bone healing has occurred, typically
about six weeks, the button is then cut from the suture and the
pullout sutureremoved by traction, that is why it must be
placed in non-locked fashion initially.The use of this technique
can be technically challenging, often requires moreextensive
dissection, and cannot be used with agrasping or locking
stitch, which can theoretically reduce the overall resistance to
gapping of the construct [though there is some data to the
contrary
(1,2) ]. Additionally,there canbepoor tolerance
by patients.
With the development of suture anchors, stable fixation of
soft tissue to bone can be achieved with less technical difficulty,
smaller incisions, and minimal dissection. Although benefit to
the patient in terms of improved outcomes has been shown only
for some procedures
(1) ,there is increasing acceptanceof
the use of sutureanchors for many hand and wrist surgeries.
The development of smaller devices has allowed wide use of
anchors, from the wrist all the way to the distal phalanx in
most patients.
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INDICATIONS
The indications for use of sutureanchors are identical to the use
of any other soft tissue to bone fixation. Avariety of common
orthopedic hand procedures have been described using suture
anchors as amethod of repair,including ligament repair or
reconstruction
(1,3–11) [i.e., metacarpophalangeal (MP) collat-
eral and scapholunate interosseous ligaments], repair of flexor
digitorumprofundus (FDP)avulsions
(1,10,11) ,swan-neck
corrections
(12),wrist or digit extensor tendon reinsertion
(12),and joint capsulodesis procedures (12–14).The design
and manufacture of newer small implants has allowed these
devices to be used in essentially all bones of the hand including
the distal phalanges (
Table 1 ).
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CONSIDERATIONS IN SUTURE ANCHORS
Numerous suture anchors are commercially available for use in
the wrist and hand. The most important consideration is the
size of the anchor relative to the bone for which it is to be
inserted. For the distal radius, anchors should be less than 3mm
in diameter and 1cminlength. Smaller anchors (in the range of
2.3! 5mm) should be used in the carpal and metacarpal bones
and yet even smaller ones in the phalanges.
The surgeon may choose either metallic (nonabsorbable) or
bioabsorbable anchors which are usually made of polylactic
acid polymers. The decision is based on surgeon preference and
comfort level. The advantages of the metal anchors are their
sturdiness during insertion and the potentially greater pullout
strength. Lack of ametallic implant to obscurex-ray views is a
benefit of bioabsorbable anchors. Additionally,inthe unfortunate circumstance of suture breakage, the surgeon can overdrill
the absorbable anchor and use the same pilot hole in the bone.
Another design consideration is the type of fixation of the
anchor to the bone. Three basic designs are in use: flanges,
toggle, and threaded screw-in. Anchors with flanges operate
based on the spring principle in which the flanges collapse in
the direction of insertion, but then deploy to embed in the bone
when tension is applied in the opposite direction (
Fig. 3 ); some
flanged anchors have interference fit. The toggle mechanism
works because of eccentric placement of the sutureeyelet on the
anchor itself. After seating the anchor into the pilot hole, tension
on the sutures will rotate (i.e., “toggle”) the anchor,wedging it
against the sides of the pilot hole (
Fig. 4 ). Threaded anchors are
screwed into the bone and purchase is determined by the outer
diameter of the anchor,the length of engagement in the bone,
the quality of the bone, and screw thread depth and pitch
(
Fig. 5 ). The type of fixation has implications when creating
the pilot hole. For flange and toggle types, the pilot hole is
slightly larger than the diameter of the anchor.Onthe other
hand, athreaded anchor requires asmaller pilot hole than its
outerdiameter. Bioabsorbablethreadedanchors may need
tapping prior to their insertion because of the lower strength
of the material.
Acompiled list of small bone suture anchor devices is
presented in
Table 1 .Itshould be noted that this is by no means
an inclusive list butcontains thedevices that theauthors
typically use.
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GENERAL SURGICAL TECHNIQUE
Regardless of the location, or which soft tissue type needs to be
attachedtobonebysutureanchor(s),the generalsurgical
technique is similar.Once the exposure is performed, the soft
tissue of interestisassessed for adequate length, tension, and
quality; the end is freshened accordingly. The repair or reconstruction should be done without undue tension or gapping at
the soft tissue–bone interface. The bony bed is prepared by
liftingthe periosteum andabrading thecorticalsurface to
increase the healing potential of the soft tissue to bone. The
next step is to select the appropriate size anchor and suture
material. Formostanchors,the pre-loadedsuturecan be
replaced by thesurgeon’s choice suture.The pilotholeis
created in the bony bed, usually with adrill, making sure to
achieve adequate depth in the bone but avoiding penetration
into the joint or far cortex. This is followed by insertion of the
anchor.Stability of the anchor is checked by pulling tension on
thesutures and there should notbeany prominence of
the anchor.
Suturing of the soft tissue can be done in anumber of
ways. Acommon technique is to run agrasping or locking
stitchthrough thesofttissuewithone endofthe suture,
followed by aseriesofsquareknots,pushing thetissue
down to thebonybed.Alternatively,the second limbis
sutured through the tissue in anon-locking fashion and tied
down as amattressstitch. Locking the second limb will prevent
sliding of the suture and risks gapping at the soft tissue–bone
interface. Tying knots onto the suture anchor in this fashion has
adifferent tactilefeel becausethe tissueisbeing pushed
insteadofbeing pulleddowntothe bone.Toget the
“normal” feelofdrawing thetissuetobone, twosuture
anchors can be used. One suture limb from each anchor is
sewn through the tissue and tied together.Tension is applied to
the free ends of the sutures; thereby pulling down the tissue.
Tying is then performed in the usual manner.
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Thumb MP Joint Ulnar Collateral Ligament Repair
By far the most common use of suture anchors in hand surgery,
as citedinthe literature,isrepair or reconstructionof
the thumb MP joint collateral ligament (
Fig. 6 ) (3–9,12,15,16).
After standard regional or general anesthetic agent and prep, a
longitudinalincisionismadedirectlyoverthe thumbMP
jointalong its ulnar mid-axial border undertourniquet
control. Initial dissection following the skin incision is meticulously performed to examine for aStener lesion [i.e., retraction
of theulnar collateralligament (UCL) proximaltothe
adductor aponeurosis] which sometimes is apparent at this
level. If no Stener lesion is present, the adductor aponeurosis is
carefully identified and incised along its ulnar border taking
care not to injure the extensor mechanism. Care is also taken to
protect the branch of the superficial radial nerve at the volar
extentofthe wound(
Fig. 6 A). Once thisiscomplete,the
underlying capsuleofthe thumbMPjoint is identified.
Oftentimes afrank capsular tear will be presentand the
UCL exposed.
Adorsoulnar incision in the capsule is made in longitudinal fashion. Great care must be taken in the distal transverse
extension of this incision to open the joint, especially when the
UCL has been completely torn but aStener lesion is not present.
It is necessary to ensure that the dissection is carried out far
enough distal with the longitudinal capsular incision in order
not to sacrifice any of the fibers of the UCL. It is often found that
the UCL, once ruptured from the base of the proximal phalanx,
can scar to the palmar plate making it appear more volar than
Sutures
2nd incision
Bone bridge
Soft tissue
FIGURE 1 Diagram of atypical configuration of soft tissuerepair
to bone using abone bridge on the far cortex. Source:Courtesy of
Virak Tan and Aaron Daluiski.
Padded
button
FIGURE 2 Diagram of atypical configuration of soft tissue repair to
bone using apullout suture tied over apadded button. Source:Courtesy
of Virak Tan and Aaron Daluiski.
6
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Daluiski and Tan
itstypical insertion on thebaseofthe proximal phalanx.
In addition, great care must be taken to ensure that the collateral
ligament has not healed back upon itself (
Fig. 6 B). If the fibers
are not carefully traced, the ligament may appear much shorter
than its true length. If this is not recognized, it may appear as
though there is inadequate length for direct repair and atendon
graft may be used inappropriately.Itisthe authors’ experience
that it is rare to require atendon graft for the repair of acute
ligamentous (i.e.,injuriesthatare notthe result of chronic
ligamentousattenuation such as traditional “gamekeepers”
injuries) rupture.
Once it is ensured that adequate ligament length is available for repair,the base of the proximal phalanx is prepared by
roughening the periosteum and cortical bone (
Fig. 6 C). The joint
is then explored. Asuture anchor is carefully placed into the
base of the proximal phalanx and checked to ensure that it is
adequately anchored to the bone (
Fig. 6 D). The ligament is then
repaired directly to the base of the proximal phalanx. With a
single knot placed in the ligament, the ligament is then checked
to ensure stability.Ifitisstable, the stitch is then used to add
additional knots between the ligament, periosteum and capsule.
The capsule is then closed in aseparate layer.Capsular repair
addsadditional support. Once hemostasisisachieved after
tourniquet is deflated, the extensor mechanism and skin are
closed are in layers.
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REHABILITATION AND OUTCOME
Rehabilitation protocols vary and should be tailored to each
specific indication. Repair of an FDP avulsion, which requires
earlyactive range of motion, may requireimplants with
stronger pullout strength than UCL repairs of the thumb MP
joint, which can be rehabbed essentially tension-free immediately after surgery.Pullout strength of several anchor devices
are at least as effective as repair over abutton for FDP avulsions
(11) and clinical outcomes are similar,with adecreased time of
return to work in patients in whom the anchors wereused
(1).
Clearly,outcome data for each specific operative procedure
are dependent on the procedureperformed. In general, the use
of suture anchorsasopposedtotraditional techniques has
yielded similar or better outcome in part due to the reduced
dissection required to achieve good fixation of soft tissue to
bone. These findings have not been proven for most clinical
uses.
TABLE 1 Selection of Small Bone Soft Tissue Fixation Devices
Anchor Manufacturer Absorbable
Drill/anchor
diameter
(mm) Suture Needle Fixation Deployment
Ultrafix Micromite
(
Fig. 2 )
Conmed
Linvatec
No 1.8/1.5 2-0 Nonabsorbable
braided polyesther
4Flanges Gun-type device
Mini-RevoConmed
Linvatec
No 1.5/2.7 #2 Nonabsorbable
braided polyester
Screw-inHandheld, screw-in
Minilok Quickanchor
Plus
Mitek Yes (polylactic
acid)
2.0 #0, 2-0, 2-0 PanacrylOs-2 (#0), V-5,
or RB-1 (2-0)
Toggle Handheld, mallet
Microfix Quickanchor
Plus (
Fig. 4 )
Mitek Yes (polylactic
acid)
1.3 3-0, 4-0 Ethibond V-4 (3-0), C-1,
or P-3 (4-0)
Toggle Handheld, mallet
Mini Quickanchor
Plus (
Fig. 3 )
Mitek No 2.1 2-0, #0 Ethibond Os-2 (#0), V-5
(2-0)
2Flanges Handheld insertion
device
Micro Quickanchor
Plus (
Fig. 3 )
Mitek No 1.3 3-0 or 4-0 Ethibond V-4 (3-0), C-1,
or P-3 (4-0)
2Flanges Handheld insertion
device
(B)
Flanges
(A)
FIGURE 3 Flanged anchor:During insertion into the bone, the flanges
collapse ( A ). After removalofthe handle, with tension on the sutures, the
flanges embed into the sides of the pilot hole, resisting dislodgement ( B ).
Source:Courtesy of Virak Tan and Aaron Daluiski.
Pilot hole
Sutures
FIGURE 4 Toggleanchor:Due to the eccentricity of the eyeslet,
tension on the sutures after insertion causes the entire anchor to rotate
and embed into sides of the pilot hole, resisting dislodgement. Source:
Courtesy of Virak Tan and Aaron Daluiski.
Use of Suture Anchors in Hand Surgery
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7
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COMPLICATIONS
Complications of sutureanchor use are similar to those for the
open techniques and are based more on the surgical procedure
performed rather than to the actual implant itself. There are,
however, some implant-specific complications whichare
worth noting.
It is importanttomatch thesizeofthe implant, both
diameter and length, with the size of the bone into which the
soft tissue is being repaired. Use of smaller implants is absolutely required for smaller bones. If not, the implant may be too
large for the bone and can cause afracture. In addition, larger
implants tend to have adrill depth commensurate with the size
of the implant. Placement of astandard suture anchor volarly in
amiddle phalanx, for example, will lead to overpenetration of
the dorsal cortex and exposure of the implant dorsally.Proper
position of theimplant shouldbeverified usingdynamic
fluoroscopy following placement.
Suturebreakage, although not necessarily acomplication
specifictosutureanchors, canleadtoquite significant
FIGURE 5 Threaded anchor :Itisinserted by screwingitintoan
undersizedpilot hole. Source:Courtesy of Virak Tan and Aaron Daluiski.
EPL
RSN
Capsule
UCL
UCL
UCL
PP
PP
MC
(A)
(B)
(C)
(E)
(D)
(F)
FIGURE 6 Intraoperative photographs of a
right hand dominant 20-year-old with an acute
leftthumbUCL injury.(A )After dissection
through theextensormechanism,asingl e
dorsal ulnar capsular incision was made. ( B )
The avulsed UCL was identified. ( C )The base
of the PP was carefully roughened using a#69
blade and rongeur. ( D )ALinvatec MicroMite
suture anchor was placed at the base of the
proximal phalanx and the ligament along with
the capsule was repaired back to the bone. This
afforded an excellent repair with complete stability to radial deviation. The capsule was then
closed followedbythe extensor mechanism
and skin. ( E & F )Post-operative radiographs
showing theposition of thesuture anchor.
Abbreviations:EPL, extensorpollicis longus;
MC, metacarpal; PP, proximal phalanx;RSN,
radial sensory nerve; UCL, ulnar collateral ligament. Source:Courtesy of Virak Tan and Aaron
Daluiski.
8
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Daluiski and Tan
complications with the use of these devices. If asuture anchor
has already been placed into the bone and the suture breaks, it is
often necessary to drill anew hole, which can lead to fracture
and destabilization of the soft tissue repair.For certain implants,
such as the MicroMite suture anchor (Linvatec Corp., Largo,
Florida, U.S.A.), it is possibletocarefully tamp the failed
implant further into larger bones and utilize the same pilot
hole. For bioabsorbable anchors, re-drilling the pilot hole over
the anchor is an option. This avoids the need for an additional
drill hole and helps minimize iatrogenicfracture. To reduce the
chance of suturebreakage, it is also possible to replace the
suturethat comes with the anchor with an appropriately sized
Fiberwire(Arthrex, Inc., Naples, Florida, U.S.A.) or equivalent
suture, prior to the initial anchor insertion.
Additional complications tend to be more site specific as
opposed to implant specific. Although failure of the implant in
terms of bone pullout is possible, most of the implants have
adequate pulloutstrengthtowithstandmuchofthe force
exerted on it during the postoperative rehabilitation
(2,9,15–
17)
.This is especially true of thumb UCL repairs where it has
been shownbiomechanically that repaired ligaments
have threetimesthe strength than theforce that the
actual ligament withstands during protected non-pinch rehabilitation
(16).
There is afair amount of attention paid to pullout strength
of thesutureanchors. Althoughitisinteresting to note
differencesinpullout strengthbetween different suture
anchors, pullout strength is not solely limited to design of the
sutureanchor but also to the quality of the bone in which it is
placed.Inaddition, sincemanyanchors provideapullout
strength that is above what is required to hold the tissue to
bone untilithealed, differences between anchors are often
not relevant.
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SUMMARY
Suture anchorshavebeen auseful adjunct in minimally
invasive surgerybylimiting the size of theincisionand
minimizing traumatic soft tissue dissection. They have been
extremely helpful in avariety of procedures in the hand and
wrist, all related to soft tissue fixation to bone. Ahost of anchors
exist that use drill diameters as small as 1.3 mm, which allow for
fixation to essentially all bones of the hand and wrist. Though
there is apaucity of clinical outcomes data, numerous biomechanical studies and case series have shown adequate anchor
pullout strength and acceptable clinical results.Due to ease of
use and limited invasiveness, sutureanchors are increasingly
prevalent in hand surgery.
&
SUMMATION POINTS
Indications
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Repair or reconstruction of ligaments
&
Repair of flexor digitorum profundus avulsions
&
Correction of swan-neck deformity
&
Reinsertion of wrist or digit extensor tendon
&
Joint capsulodesis
Outcomes
&
Similar or better outcome to open procedures to attach soft
tissue to bone
Complications
&
Similar to those for the open techniques
&
Iatrogenic fracture or prominence of implant if the anchor is
too large for the bone
&
Suturebreakage
&
REFERENCES
1. McCallister WV,etal. Comparison of pullout button versus suture
anchor for zone Iflexor tendon repair.JHand Surg [Am] 2006;
31(2):246–51.
2. Kusano N, et al. Supplementary coresuturesincrease resistance to
gapping for flexor digitorum profundus tendon to bone surface
repair—an in vitrobiomechanical analysis. JHand Surg [Br] 2005;
30(3):288–93.
3. Zeman C, et al. Acute skier’s thumb repairedwith aproximal
phalanx suture anchor.AmJSports Med 1998; 26(5):644–50.
4. Weiland AJ, et al. Repair of acute ulnar collateralligament injuries
of the thumb metacarpophalangeal joint with an intraosseous
sutureanchor.JHand Surg [Am] 1997; 22(4):585–91.
5. Tuncay I, Ege A. Reconstruction of chronic collateralligament
injuries to fingers by use of sutureanchors. Croat Med J2001;
42(5):539–42.
6. McDermott TP,Levin LS. Sutureanchor repair of chronic radial
ligament injuries of the metacarpophalangeal joint of the thumb.
JHand Surg [Br] 1998; 23(2):271–4.
7. McCall J. Acute skier ’s thumb repairedwith aproximal phalanx
sutureanchor.AmJSports Med 1999; 27(3):390–1.
8. Kato H, et al. Surgical repair of acute collateral ligament injuries in
digits with the Mitek bone sutureanchor.JHand Surg[Br] 1999;
24(1):70–5.
9. Beauperthuy GD, Burke EF.Alternative method of repairing
collateralligament injuries at the metacarpophalangeal joints of
the thumb and fingers. Use of the Mitek anchor.JHand Surg [Br]
1997; 22(6):736–8.
10. Silva MJ, et al. The effects of multiple-strand suturetechniqueson
the tensile properties of repair of the flexor digitorumprofundus
tendon to bone. JBone Joint SurgAm1998; 80(10):1507–14.
11.Brustein M, et al. Bone sutureanchors versus the pullout button for
repair of distal profundus tendon injuries: acomparison of strength
in human cadaveric hands. JHand Surg [Am] 2001; 26(3):489–96.
12. Khandwala AR, Khan IU, Elliot D. The use of Acufex wedge tag
tissue anchorsinhand surgery.JHand Surg[Br] 2004; 29(1):22–5.
13. CuenodP.Osteoligamentoplasty and limited dorsal capsulodesis
for chronic scapholunatedissociation. Ann Chir Main Memb Super
1999; 18(1):38–53.
14. Saffar P, Sokolow C, Duclos L. Soft tissue stabilization in the
management of chronic scapholunateinstability without osteoarthritis. A15-year series. Acta Orthop Belg 1999; 65(4):424–33.
15. Firoozbakhsh K, et al. Astudy of ulnar collateral ligament of the
thumb metacarpophalangeal joint. Clin Orthop Relat Res 2002;
403:240–7.
16. Harley BJ, Werner FW,Green JK. Abiomechanical modeling of
injury,repair,and rehabilitation of ulnar collateralligament
injuries of the thumb. JHand Surg [Am] 2004; 29(5):915–20.
17. Schuind F, et al. Flexor tendon forces: in vivo measurements.
JHand Surg [Am] 1992; 17(2):291–8.
Use of Suture Anchors in Hand Surgery
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3
The Role of Bone Graft Substitutes in Minimally Invasive
Surgery of the Wrist and Hand
Vikrant Azad, Ankur Gandhi, Frank Liporace, and Sheldon Lin
Department of Orthopedics, The New Jersey Medical School, University of Medicine and Dentistry of New Jersey,
Newark, New Jersey, U.S.A.
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INTRODUCTION
The standard technique to facilitate bone healing process is the
harvest and application of autogenous bone graft. Iliac crest
autograft remains today’s gold standard,since it is the only
material that contains thethree essential bone formation
elements: cells, matrix, and critical growth factors. Approximately340,000 patients undergo iliac crest graftharvesting
procedure annually; however,autogenous bone graft comes
with significant costs. Harvesting of iliac crest bone can be
associated with significant clinical morbidity which includes
donor site pain, scarring, increased surgical time, blood loss,
and risk of infection. There is also prolonged hospitalization,
delayed rehabilitation, and surgical complications, such as iliac
fracture,hematoma,nerve injury,vascularinjury,lumbar
hernia, etc. (1–3). Areview of the literaturereveals that the
complication rate can be as high as 31%, with approximately
27%ofthe patients continuing to feel pain at 24 months
following surgery (4). In addition, the quantity of available
graft harvested may be less than optimal. These reasons have
led to the development and validation of alternative processes
that are capable of replicating the performance of the iliac crest
graft, while eliminating the associated complications. Avariety
of materials have been utilized as substitutes for autologous
bone graft. Ceramicsare oneclassofsynthetic bone graft
substituteswhich havebeenveryusefulinmany clinical
orthopedic applications and have served as auseful adjunct
to minimally invasive surgery for the wrist and hand.
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General Overview of Ceramic Bone
Graft Substitutes
Ceramics are highly crystalline materials formed by heating
nonmetallic mineral salts to ahigh temperatureinaprocess
calledsintering. The porousnature of thesecompounds
providesanosteoconductivescaffoldtowhich chemotactic
factors, circulating osteoinductive growth factors, and mesenchymal stem cells can migrate and adhere. This scaffold provides a
critical structure for progenitorcells to differentiate into functioningosteoblasts.Besidesbeing biocompatibleand
bioresorbable,the crystallinestructure of ceramics yields a
material verysimilar to naturalbone. Syntheticbonegraft
substitutes have several disadvantages which include alack
of osteogenic cells and the absence of osteoinductive potential
normally found in allografts. However,the widespread availability of ceramic bone graft substitutes and the absence of
allograft-induced immunogenic response or pathogen transmissionprovideanincreasing incentive forthe useof
ceramics. In addition, the surgical complications of retrieving
bone from an autologous donor site can be avoided (3,5,6).
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General Physical Properties of Ceramics as Bone
Graft Substitutes
Physical properties such as pore size and porosity are critical
parameters of syntheticbone graft substitutes. Blood vessel
penetrationintothe bone graftsubstituteisnecessary for
bone-forming cells to lay down new bone while the graft is
being resorbed. To allow vascular ingrowth, the graft should
have apore size largeenough to allow the vessels to grow into
the graft. Previously,pore size was considered to be the most
critical variable influencing bone formation within synthetic
bone graft substitutes (7). Osteoid tissue forms when the pore
size is greater than 100 m mwith apore size of 300 to 500 m m
being ideal. Porosity,which is the interconnectivity of pores, is
currently consideredtobethe more critical parameter
compared to pore size (8). In the absence of adequate interconnectivity,the pores act like blind alleys with low oxygen
tension at the pore apex. The relatively poor oxygen tension
impairs the differentiationofmesenchymalcells toward an
osteoblast cell lineage and instead leads to differentiation of
mesenchymal cells into fibrous tissue, cartilage, or fat (9).
The in vivo degradation of cements has been another area
of active research focused on making the degradation rate
morepredictable and closer to the rate of new bone formation. Ideally,abone graft substitute is expected to resorb at
the same rate as new bone is being synthesized and remodeled. If the rate of resorption is greater than the rate at which
new bone can be laid down, the structural integrity of the
bone graft substitute will collapse. On the other hand, aslow
degradation rate will impede new bone formation resultingin
an alteration of the local mechanical properties of bone. For
example, hydroxyapatite is aslowly degrading calcium phosphate ceramic. The in vivo degradation of hydroxyapatite
occurs over yearsand traces canbeseeninthe bone
decades after implantation (10,11).
Currently, thereare twogeneral commercialformu-
lations of ceramic bone graft substitutes, calcium phosphate
and calciumsulfate products. Both of thesebonegraft
substitutes are used in two physical forms, solid (pellets,
blocks) and injectable (paste/putty). The remainder of this
chapter is dedicated to discussion of these products and their
applicationtominimally invasive surgery of thewrist
and hand.
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CALCIUM PHOSPHATE CEMENTS
Calcium phosphate exists in three basic ionic combinations with
phosphate—tribasic (tricalciumphosphate, TCP), dibasic
(secondary calcium phosphate), and monobasic calcium phosphate. Of these three forms, TCP is most commonly used in
the manufacturing of calcium phosphate-based cements. TCP is
available in two forms, alpha and beta TCP.Both are hightemperature TCPs with achemicalcomposition similarto
amorphous TCP with alpha TCP being morecrystalline than
beta TCP (12). Alpha TCP is also moresoluble than beta TCP
and is amajor component of calcium phosphate cements (13).
In addition, alpha TCP has been reported to undergo faster
degradation in vivo compared to beta TCP (13). However,the
literaturehas also shown that beta TCP can undergo afaster
degradation than alpha TCP in vivo (14).
The injectable formofcalciumphosphate cement is
prepared by mixing various types of calcium phosphates
with an aqueous solution. The resulting paste hardens to
form acalcium phosphate apatite of low crystalline order
and small crystal size similar to the mineral phase of bone.
Brownand Chow prepared thefirst calciumphosphate
cementthatcouldbeconstituted at room temperature
usingequimolar concentrationsoftetracalciumphosphate
and calciumhydrogen phosphate (15). Initially,dicalcium
phosphate dihydrate is formed with aplate-like morphology
which ultimately later yields calcium-deficient hydroxyapatite. All current formulations of calcium phosphate cement
areconstituted viaanendothermic reactioninstead of
exothermic reaction thereby limiting the potential for local
tissue damage.
Calciumphosphate cement hardening occursmostly
within thefirstsix hours,yieldingan80% conversion to
hydroxyapatite with acompressive strength of 50 to 60 MPa.
Hardeningcan be accelerated with phosphate solution, sodium
fluoride, or sodium hydrogen phosphate.Porositycan be
introduced into the bone graft substitute by the addition of
soluble inclusions such as sucrose, sodium hydrogen carbonate,
or sodium hydrogen phosphate with the goal of improving
osteoconductivity (16). The low temperatureofformation and
the inherent porosity also permit the addition of antibiotics to
prevent bone infections or growth factors to stimulate differentiation of mesenchymal cells.
Becausethe compositionofcalciumphosphateapatite
cements is similartonaturalboneapatite, thephosphatebasedcementundergoes increased biological degradation
compared to calciumsulfate.Experimental studiesinvivo
have shown that multinucleated osteoclast-like cells surround
the implanted cement. At the same time, new bone is formed by
osteoblasts and progresses into the scaffold provided by the
apatite cements (14,17,18). The average resorption rate of the
cement depends on many factors such as the composition of
cement,site of implantation, patients’metabolic rate,and
generalhealth. Comparingthe experimental resultsofthe
degradations processes can often be difficult due to the variability in study protocol and design.
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CALCIUM SULFATE CEMENTS
Dreesmann used calcium sulfate as early as 1892 for cavitary
bone lesions and observed healing in six of nine lesions (19).
Peltier did the significant early work on calcium sulfate in bone
healing andfirstdescribed hisexperienceinapreliminary
report in 1959 (20).Later, Peltierand Jonesreportedtheir
long-term follow-up results on 26 unicameral bone cysts of
which24healedwithout complications (21).Several other
authors have reported their results with the use of calcium
sulfate as abone graft substitute and in general have shown
positive results. Despite the early work, in recent years, calcium
phosphate-based cements have superseded calcium sulfate in
their usage as injectable cement.
Calcium sulfate as abone graft substitute is available in two
chemical forms—calcium sulfate hemihydrate (plaster of Paris)
and calcium sulfate dihydrate (gypsum). Calcium sulfate dihydrateproduced afterhydration of thehemihydrate form
is chemically stable andavailable in solidshapessuch as
pellets and blocks. Hemihydrate when mixed with adiluent
(water,saline, or other liquids) undergoesahydration reaction
to form aputty/paste and is converted into the dihydrate form.
In this putty form, the calcium sulfate is injectable until it sets in
as solid calcium dihydrate. Special care in the processing of
calcium sulfate needs to be maintained in order to produce
surgical grade calcium sulfate with apredictable resorption rate
and optimal crystalline structure to provide an osteoconductive
medium for new bone ingrowth.
The mechanism of calcium sulfate resorption is not well
understood but calcium sulfate appears to resorb by dissolution
into surrounding body fluids rather than by being actively
degraded by cellular mechanisms (22,23). Recent literaturehas
suggested that calcium sulfate may not be osteoconductive and
that newboneformation occurs as thecementdissolves,
possibly acting as abone void filler (24). The resorption of
calcium sulfate in vivo is rapid and thus not suitable for clinical
situationswhere cementisrequiredtoprovidestructural
support. Therefore, calcium sulfate used alone is useful for
contained nonstructural defects or as an adjunct to fixation
devices to improve their holding strength in bone. Calcium
sulfate can also be used as acarrier for growth factors in the
appropriate clinical applications (24–26).
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INDICATIONS
The indications are still evolving for uses of calcium phosphate
and calcium sulfate cements. Clinical experience withthese
bioactive cements in distal radius fracturesand bone lesions
(such as simple bone cysts, aneurysmal bone cysts, or enchondromas) is increasing. In the distal radius, these cements are
especially useful in fractures with severe comminution, bone
loss at the fracturesite, or fracturesinvolving osteoporotic bone
whichare difficult to stabilize. Injectable bone cements,by
providingadditionalmechanicalstability,can reduce the
immobilization time,allow earlier range of motion exercise
and thereby facilitate rapid recovery (27–29).
Bone lesions often requirebone graft to fill the defect which
may be the result of the primary pathology or from curettage.
Use of calcium-based bone graftsubstitutes in this setting
obviates the need to obtain autologus bone graft. Additionally,
because the material can be injected into the defect, only asmall
corticalwindowisrequired; thereby, minimizing further
compromises to the integrity of the native bone.
Areported complication is extrusion of the cement into the
joint. Metaphysealfractures frequently havesubtle intraarticularextensionsand thecementwheninjected under
pressure maypermeatethrough theseintra-articular extensions. Once in the intra-articular space, the cement can cause
persistent pain and wound drainage/infection. Lobenhoffer et
al. reported apatient who developed sterile wound drainage
with use of injectable cement for atibial plateau fracture(30).
Thewound wasrevised butnocause wasfound.Due to
persistent drainage, asecond revision was done and this time
on opening the suprapatellar recess, two small pieces of cement
was found which werenot visible in the postoperative radiographs. After removal of these loose bodies, healing progressed
normally.
Cement remaining in the soft tissue can also be acause of
persistent postoperative pain. Kopylov et al. in their study on
12&Azad et al.
the use of injectable calcium phosphate cement in distal radius
fractures had two patients who appeared to have morepostoperative pain in the wrist. In both the cases, cement was found
in the soft tissue (28). Although both calcium phosphate and
calcium sulfate have good biocompatibility,several reports of
inflammationwith their useexist (31,32).Calciumsulfate
appears to induce an inflammatory reaction to alesser degree
than calcium phosphate.
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SURGICAL TECHNIQUES
Whether the calcium cement is to be used to augment adistal
radius fractureorfill abone lesion, the general technique is the
same. Preparation of the cement should be done according to
the manufacturers’ specific recommendations. Different formulations of theceramic cementshavedifferent mixingand
injection times; therefore, it is important that the scrub nurse/technician is familiar with the system.
The surgical setup, equipments, instruments, implants,
and initial portion of the surgical procedure are done as they
would be normally.Distal radius fractures are reduced and
stabilized, and bone lesions are curettaged, as needed. The
bony defect canthenbeaccessed throughthe surgical
incision or percutaneouslywithadeliveryneedle.An
image intensifier can be used to confirm that the needle is
within the void. Saline is irrigated through the needle to
evacuate any hematoma. Injection is begun by docking the
syringe onto the preplaced needle and backfilling the defect.
The needle is slowly withdrawn as fill is achieved. Image
intensification is used to ensure that the void is completely
filled. Excess material outside of the defect is removed, after
which the injected material is allowed to solidify without
disturbance. After the material has harden, light irrigation is
performed and closure is done per routine.
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CASE EXAMPLE
A43-year-old right-hand dominant male sustained an intraarticular left wrist fracture (Fig. 1). Notable in the history
was that he receives hemodialysis (HD) through an arteriovenousshunt in theipsilateral arm(Fig. 2).Operative
stabilization wasrecommended becauseofthe articular
depression andthe fact that immobilization of thewrist
wouldprecludeuse of theshunt forHD. Aminimally
invasive techniquewas chosen to minimize postoperative
swelling and avoid tourniquet use in that arm. The articular
step-off wasreducedbyuse of an elevator through the
cortical window in the radial styloid (Fig. 3). After placement
of theMICRONAIL (Fig.4), percutaneousinjectionof
calciumphosphatecement(Norian SRS; Synthes, Paoli,
Pennsylvania, U.S.A.) into the metaphyseal bony defect was
performed to provideadditionsupport of thearticular
surface (Fig. 5). Postoperatively,the patient was able to get
HD throughthe armonthe followingday because no
immobilization was required (Fig. 6).
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OUTCOMES
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Distal Radius Fracture
Few clinical studies exist regarding the role of calcium cements
in thetreatment of acutedistalradiusfracturesand those
that displaced after conservative management. Cassidy et al.
FIGURE 1 Posterior–anterior and lateral radiographs of the intra-articular distal radius fracture of the patient.
Source:Courtesy of Virak Tan, MD.
The Role of Bone Graft Substitutes
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