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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_574_Библиотеки_им_академика_М_И_Перельмана.pdf
performed aprospective, randomized multicenterstudy to
evaluate closed reductionand immobilizationwith and
withoutcalcium phosphate cement (Norian SRS)inthe
management of distal radial fractures(33). Atotal of 323
patients with adistal radial fracture were randomized to a
treatment groupconsisting of aclosed reduction and Norian
SRS, and acontrol groupconsisting of aclosed reduction and
application of acast or external fixator.Inthe treatment group,
wrist motion was encouraged beginning two weeks postoperatively while in thecontrol group,the fixatororcastwas
continued for six to eight weeks. Significant clinical differences
were seen at six and eight weeks postoperatively resulting in
better grip strength, wrist range of motion, digital motion, use
of thehand, andsocial andemotionalfunction, with less
swelling in the patients treated with Norian SRS than in the
control group.Bythree months,there werenosignificant
differences except for digital motion, which remained significantly better in the group treatedwith Norian SRS. At one
year,noclinical differences weredetected. Radiographically at
sixtoeight weeks, both groups wereequivalentwith the
exception of the change in ulnar variance, which was higher
in the treatment group(2.2 mm compared with 1.5 mm) (33).
Similar results were reported by Kopylov et al. in arandomized
study on failed conservative treatment of distal radius fractures
or redisplaced distal radius fractures (34). The study compared
calcium phosphate cement followedbycast immobilization
with external fixator alone.
Sanchez-Sotelo et al. performed aprospective, randomized
study on 110patients older than 50 years with distal radius
fractures to compare the outcome of conservative treatment to
implantation of moldable bone cement and immobilization in a
cast for two weeks (35). The authors reported that patients
treated with Norian SRS had less pain and earlier restoration
of movement andgripstrength.Satisfactoryresults were
demonstrated in 82% of the Norian SRS patients and 55% of
the control group. The rates of malunion were 18% and 42%,
respectively.Soft-tissue extrusion was present initially in 69% of
the Norian SRS patients decreasing to 33% at one year.
Zimmermann et al. performed aprospective study on 52
menopausal, osteoporotic women with unstable intra-articular
distal radius fractures to compare the outcome of percutaneous
pinning and immobilization in acast for six weeks to the use of
injectable calciumphosphate bone cement (NorianSRS)to
supplement pin and screw fixation with immobilization in a
cast for three weeks (36). All patients were reviewed on average
twoyears (range 21–29 months)after surgery. Theauthors
reported that patientstreatedwith Norian SRShad better
functionaloutcome,restorationofmovement, and grip
strength. In the treatment group, there was a1-mm loss of
radial length, a38 loss of radial inclination and a78 loss of
palmar tilt. In the control group, the radial length decreased by
3mm, radial inclination decreased by 118 ,and palmar tilts by
128 .Loss of reduction was significantly higher in the control
group comparedwith the treatment group.
In apreliminary report, Jupiter et al. reported their results
on the percutaneous use of injectable calcium phosphate cement
(Norian SRS) in five patients with distal radius fracture (29).
The purpose of the study was to evaluate the feasibility of
Norian SRS bone cement injected percutaneously into adistal
radius following reduction in preventing loss of reduction as
well as safety.All fractures werereduced under regional or
general anesthesia and the cement was introduced via acatheter
system into the metaphyseal defect of the fracture. Ashort arm
cast was applied and remained in place for six weeks. Prospective follow-up at 12 months showed an average loss of ! 1mm;
radial anglemaintainedatanaverage of 25.48 ;and volar
anglewas within the normalrange (0–21 8 )infour patients
whileone patienthad adorsalangle of 7 8 .Wrist motion
improved 50%betweensix weeksand threemonthsand
improved further by 12 months when grip strength reached a
FIGURE 2 Clinical photograph of ahemodialysis patient who sustained
adistal radius fracture in the ispilateralwrist. Source:Courtesy of Virak
Tan, MD.
FIGURE 3 Reduction of the articular depression with an elevator placed
through the cortical window at the radial styloid. Source:Courtesy of
Virak Tan, MD.
14
&
Azad et al.
mean of 88%ofthe contralateralside. Dorsaland volar
extrusion of injectedcement in four patientsresorbed over
time. There were no clinically significant adverse effects or
complications. The authors concluded that cement proved to
be clinically safe and effective as acancellous bone cement to
maintain fracturereduction of unstable extra-articular distal
radius fractures.
In an unpublished series, Paige (37) augmented 15 patients
whounderwentinternalfixation of unstable distal radial
fractureswith injectable calciumsulfate bone graftdue to
dorsalfragmentation and an associatedmetaphysealbone
void.All patients had prospectiveevaluation using the
patient-rated wrist evaluation (PRWE) form at aminimum of
3monthsand againat6and 12 months afterfixation.
The fractures united within 6to12weeks with restoration of
anatomical positioninahigh percentage. The return to
functional activities was highlighted by improvement in the
PRWE Scores. In summary,the author concluded that volar
locking platefixation maybenefitfor bone graftsubstitute
augmentation for the morecomplex, unstable fracturepatterns.
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Bone Lesions
Injectable ceramic bone cements provide asuitable bone-filling
material for cystic lesions since it can be used with minimal
trauma to the thin cortical shell around the lesions and also
provides immediate structural support.
Few clinical studies exist regarding the use of injectable
calcium phosphate bone cements in the management of bone
lesions. Joosten et al. reportedaone-year prospective study of
eight patients with enchondroma whoweretreatedwith
calcium phosphate cement (BoneSource, Howmedica, Rutherford,New Jersey,U.S.A.) without fixation (38). All patients had
afull functional recoverywithout any complications. In another
study,Yasuda et al. reported10patients with digital enchondroma (six proximal phalanges, two middle phalanges, and two
FIGURE 4 MICRONAIL fixation. Source:Courtesy of Virak Tan, MD.
FIGURE 5 Calcium phosphate bone graft substitute cement was injected percutaneously into the metaphyseal
defect. The cement appears as aradiodense material on fluoroscopic images. Source:Courtesy of Virak Tan, MD.
The Role of Bone Graft Substitutes
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15
metacarpal bones) treated with an injectable calcium phosphate
bone cement aftercurettage of thelesions through asmall
cortical window (39). No postoperative splint was used and
only abulky dressing was applied. One week after surgery,
range of motion exercises werestarted. Serial radiographs were
used to evaluate bony incorporation and absorption of cement.
Incorporationofcement(defined by authorsasaseamless
change of radiographic appearance and no gap between cancellous bone and cement) occurred at an average of 4.5 months
(range 3–6.1 months) after surgery.All patients had full range of
motion aftersurgery.All butone patientreturnedtotheir
ordinary daily activities within four weeks of surgery (39).
In another study,Gaasbeek et al. reported their results with
use of plaster of Paris in 19 enchondromas of foot and hand in 19
patients.After thorough curettage of enchondroma lesions,
sterile plaster of Paris tablets wereused to fill the cavities.
After amean follow-up of 53 months (range 15–139 months),
the mean functional Musculoskeletal Tu mor Society Score was
reported as 29.1 points (97%; range 28–30) and no local recurrence was seen. The authors concluded that plaster of Paris
appearssafeand effective as abone-fillingsubstance after
curettageofenchondroma (40).
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SUMMARY
Ceramic-based synthetic bone graft substitutes, which include
calciumphosphateand calciumsulfate,haveundergone
significant development in the past decade. These bone graft
substitutes offer several distinct advantages over autograft and
other groups of bone graft substitutes. Though autograft is still
thegoldstandard in bone grafting, significant number of
disadvantages exists. The ceramic cements fulfill many of the
requirements of an ideal bone graftyet overcome several
disadvantages of autograft as well. Because autologous bone
does not need to be harvested, by definition these bioceramic
substitutes are “minimally invasive.”
In recent years, minimally invasive technologies and techniques have revolutionized many typesofsurgeries.The
injectable calciumphosphate and calciumsulfate-based
ceramic bone graft substitutes are one more addition to the
armamentariumofminimallyinvasive orthopedic surgery.
Injectable cements are generally used as an adjunct to internal
fixation for the treatment of fracturesorasbone void fillers. The
cements harden endothermically which limits tissue damage
while developing acompressive strength intermediate between
cortical and cancellous bone.
Anumber of studies have been done to evaluate injectable
cements in clinical situations including trauma such as distal
radius fractures, tibial plateau fractures, calcaneous fractures,
and vertebroplasty,and benign bone lesions such as enchondromas.However,furtherstudies needtobeconducted to
evaluate theroleofinjectablecalcium sulfate andcalcium
phosphate cements in the management of bone cysts in the
hand and forearm. As new data from preclinical and clinical
studies accumulate, the clinical uses of these bone graft substitutes will be expanded and enhanced.
Most studies in general have shown positive results with
the use of these substitutes. However,disadvantages do exist
for these bone graft substitutes. The cements are known to lack
osteogenic or osteoinductive potential and exhibit poor strength
under sheer stress. Inflammatory reactions to loose bodies in the
joints can complicate their use in asmall percentage of patients.
Besides these clinical limitations, one practical pitfall which
preventstheir widespread use is the high cost of injectable
cements.
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SUMMATION POINTS
Indications
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Distal radius fractureswith metaphyseal comminution
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Simple bone cysts
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Aneurysmal bone cysts
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Enchondromas
Outcomes
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Less pain
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Earlier restoration of movement and grip strength
Disadvantages
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Lack osteogenic or osteoinductive potential
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Poor strength under sheer stress
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Extrusion into soft_tissue and joint space may cause inflammatory reactions in asmall percentageofpatients
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High cost
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bone graft surgery.Clin Orthop Relat Res 1979; 140:204–7.
FIGURE 6 Apostoperative clinical photograph showing the incisions for
the minimally invasive techniques of distal radius fracture fixation and
bone substitute cement placement. There is minimal swelling in the wrist
even in this early postoperative time. Source:Courtesy of Virak Tan, MD.
16
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Azad et al.
2. Lotem M, Maor P, HaimoffH,etal. Lumbar hernia at an iliac bone
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4. Gupta AR. Perioperative and long-term complications of iliac crest
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6. Arrington ED, Smith, WJ, Chambers,HG, et al. Complications of
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8. Eggli PS, Muller W, Schenk RK. Porous hydroxyapatite and
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10. Klein CP,Driessen AA, de Groot K, et al. Biodegradation behavior
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11.Frayssinet P, TrouilletJL, Rouquet N, et al. Osseointegration of
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chemical composition. Biomaterials 1993; 14(6):423–9.
12. Termine JD, PeckauskasRA, Posner AS. Calcium phosphate
formation in vitro. II. Effects of environment on amorphous–crystalline transformation. ArchBiochem Biophys 1970; 140(2):318–25.
13. Laurencin CT,ed. Bone Graft Substitutes. West Conshohocken:
ASTM International, 2003:281–99.
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minipigs. JBiomed Mater Res 2002; 63(2):115–21.
15. Brown, WaC, LC, Dental restorative cement pastes. American
Dental Association Health Foundation: U.S. 1985.
16. Takagi S, Chow LC. Formation of macroporesincalcium phosphate cement implants. JMater Sci Mater Med 2001; 12(2):135–9.
17. Welch RD, Zhang H, Bronson DG. Experimentaltibial plateau
fractures augmented with calcium phosphate cement or autologous bone graft. JBone Joint Surg Am 2003; 85-A(2):222–31.
18. Sarkar MR, Wa chter N, Palka P, et al. First histological observations
on the incorporation of anovel calcium phosphate bone substitute
material in human cancellous bone. JBiomed Mater Res 2001;
58(3):329–34.
19. Dressmann H. Ueber knochenplombierung bei hohlenformigen
defekten des knochens. Beitr Klin Chir 1892; 9:804–10.
20. Peltier LF.The use of plaster of paris to fill large defects in bone.
Am JSurg 1959; 97(3):311–5.
21. Peltier LF,Jones RH. Treatment of unicameral bone cysts by
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Surg Am 1978; 60(6):820–2.
22. Pietrzak WS ,Ronk R. Calcium sulfate bone void filler: areviewand a
look ahead. JCraniofac Surg 2000; 11(4):327–33 (discussion 334).
23. Bucholz RW.Nonallograft osteoconductive bone graft substitutes.
Clin Orthop Relat Res 2002; 395:44–52.
24. Damien CJ, Parsons JR. Bone graft and bone graft substitutes: a
review of current technology and applications.JAppl Biomater
1991; 2(3):187–208.
25. Rosenblum SF,Frenkel S, Ricci JR, et al. Diffusion of fibroblast
growth factor from aplaster of Paris carrier.JAppl Biomater 1993;
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26. Cesari C, Gatto MR, MalucclliF,etal. Periodontal growth factors
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formation of the mineral phase of bone. Science 1995;
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28. Kopylov P, Jonsson K, Thorngren KG, et al. Injectable calcium
phosphate in the treatment of distal radial fractures. JHand Surg
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29. Jupiter JB, Wi nters S, Sigman S, et al. Repair of five distal radius
fractures with an investigational cancellous bone cement: apreliminary report. JOrthop Tr auma 1997; 11 (2):110–6.
30. Lobenhoffer P, Gerich T, Witte F, et al. Use of an injectable calcium
phosphate bone cement in the treatment of tibial plateau fractures:
aprospective study of twenty-six cases with twenty-month mean
follow-up. JOrthop Tr auma 2002; 16(3):143–9.
31. FlautreB,Delecourt C, Blary MC, et al. Volume effect on biological
properties of acalcium phosphate hydraulic cement: experimental
study in sheep. Bone 1999; 25(Suppl.2):35S–9.
32. Robinson D, Alk D, Sandbank J, et al. Inflammatory reactions
associated with acalcium sulfate bone substitute.Ann Tr ansplant
1999; 4(3–4):91–7.
33. Cassidy C, Jupiter JB, Cohen M, et al. Norian SRS cement
compared with conventional fixation in distal radial fractures. A
randomized study.JBone Joint Surg Am 2003; 85-A(11):2127–37.
34. Kopylov P, Runnqvist K, Jonsson K, et al. Norian SRS versus
external fixation in redisplaceddistal radial fractures. Arandomized study in 40 patients. Acta Orthop Scand 1999; 70(1):1–5.
35. Sanchez-Sotelo J, Munuera L, Madero R. Treatment of fractures of
the distal radius with aremodellablebone cement: aprospective,
randomised study using Norian SRS. JBone Joint SurgBr2000;
82(6):856–63.
36. Zimmermann R, Gabl M, Lutz M, et al. Injectable calcium phosphate bone cement Norian SRS for the treatment of intra-articular
compression fractures of the distal radius in osteoporotic women.
Arch Orthop Trauma Surg 2003; 123(1):22–7.
37. Joosten U, Joist A, Frebel T. The use of an in situ curing
hydroxyapatite cement as an alternative to bone graft following
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25(3):288–91.
38. Paige R. Distal radial fractureaugmentation with injectable bone graft sustitute—The Geelong Experience.2006:
Melbourne,Australia (personal communications).
39. Yasuda M, Masada K, TakeuchiE.Treatment of enchondroma of
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The Role of Bone Graft Substitutes
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4
Bioabsorbable Implants in Hand and Wrist Surgery
Mark L. Kavanagh, Regis L. Renard, and John T. Capo
Department of Orthopedics, The New Jersey Medical School, University of Medicine and DentistryofNew Jersey,
Newark, New Jersey, U.S.A.
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INTRODUCTION
Metal implant devices have along, reliable clinical history,
are relatively cheap, and easy to produce and shape. These
implants used in hand and wrist surgery alsohave their
disadvantages. Largedifferences between Young’s moduli of
the implants and bone often lead to stress shielding resulting
in osteopenia which may result in pathologic fractures (1).
In addition, elevated stress concentration at the junction of the
implants andthe host bone may result in periprosthetic
fractures. Implantation of metallicdevices oftenrequires
significantsofttissue strippingwhich reducesthe local
bloodsupplyabout theimplant.Thiseffectisconstant
during theentiretime the implant is in place. Metallic
devices also have the potential for corrosion and wear and
debris formation with subsequent metallosis (2). Prominent or
protruding metallic hardware may interfere with surrounding
tissues that disturb joint movement, tendon gliding, or even
cause tendon ruptures resulting in pain and loss of function.
This effect is particularly important around the hand and
wrist. Often times these implants need to be removed. Stern
et al. (3) and Berman et al. (2) have reported aneed for plate
removalin25% of casesofmetacarpaland proximal
phalangeal fractures.
An ideal implant would ensure adequate bone fixation,
transfer increasing load to bone, not affect skeletal growth, and
need notberemoved.Bioresorbableimplants canavoid
problems associatedwith metal implants,suchasstress
shielding, corrosion, wear and debris formation, and the need
for implant removal (4).
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EVOLUTION OF IMPLANTS
During thelastfew decades, theinterestinsafe, reliable
resorbable implants has steadily increased. The first application
of this technology came with the use of bioresorbable polymers
in sutures, such as Dexon (US Surgical,Norwalk, Connecticut,
U.S.A.) and Vicryl (Ethicon, Somerville, New Jersey,U.S.A.).
Thereare nowresorbableimplants designedfor trauma
surgery,including pins, screws, plates, dowels, anchors, and
membranes. Bioresorbable implants must meet several biologicaland technicalrequirements(4).Theymust notinduce
adverse inflammatory or foreignbody reactions. The implants
must not be carcinogenic, mutagenic, or teratogenic, must not
cause allergic,hypersensitive,ortoxic responses, and must
not activate the complement system (5). Resorbable implants
need to maintain adequate mechanical properties in vivo for the
desired time and degrade at an effective rate required for bone
healing. Mechanical properties aredeterminedbythe conditions of polymer synthesis, the processing of materials into
implants, and by the sterilization process of implants.
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IMPLANT PROPERTIES
Degradation of implants manifest as implant fragmentation,
strength loss, and reduction of polymer molecular weight (6–9).
Degradationofthese implantsinvivo proceedsvia abulk
hydrolysis of ester bondsthat arepresent in the polymer
chain. These materials degrade to monomeric acids and eventually to carbon dioxide and water that are removed from the
body via respiratory routes and kidneys during Krebscycle.
Physical factors that affect tissue response to implants include
implant shape, physical structure,mass of the implant, stress at
the implantation site, and micromotion at the implant–tissue
interface (4). Clinically large bulky implants with fast degrading
polymerscan causealarger inflammatory reaction when
compared with smallerimplantswithslowlydegrading
polymers.
The earliest resorbable implants weremade from polyglycolic acid (PGA), but this material is relatively hydrophilic
and highly crystalline and will degrade and lose its strength
very rapidly in thebody. It may alsogiverisetofluid
accumulation and sterile sinus formation. This material is no
longer used in orthopedic fixation devices.
Today,copolymerization can be used to create implants
with different ratios of monomers (
D and L monomers) to alter
the chemical and physical properties (4,10). The
L isomer of
polylactide (PLLA) is the material found in most orthopedic
implants used today.This isomer has ahigh degree of crystallinity andismoreresistant to hydrolysis.Apure PLLA
remains detectable forbetween18monthsand 4years
in vivo. The
D isomer (PDLLA) is amorphous and provides
less tensile strength. It promotes resorption of the implants
over alonger period of time. Currently, bioabsorbable implants
are available in avariety of plates, screws,and smooth pins
(Figs. 1–3).
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PROCESSING AND STERILIZATION
Self-reinforcing (SR) manufacturing technique enablesthe
processingofbioabsorbable polymers into high strength,
high-modulus implants (9,11–13). Ahigh degree of molecular
orientation makes the self-reinforced implants stiffand strong
in the direction of their long axis, which increasesthe mechanical strength, modulus, and toughness of theimplants.
The bending modulus of SR devices is close to that of cortical
bone (10–17GPa), whichisimportantfor bone healing
(12,14,15).The high bendingmodulus of metallic implants
(100–250 GPa) leads to stress shielding in the bone in loaded
areas (13). SR implants also have better handling properties. SR
plates can be bent with pliers to conform to the bone at room
temperaturewithout significant loss of strength.
Problems can occur with sterilization of these implants
(16,17). High-energy irradiation causes extensive degradation
and loss of mechanical properties. Ethylene oxide sterilization
does not practically affect mechanical and molecular properties
of theimplantsbut thereare concernsabout residuesand
environmental problems (17). Newer sterilization techniques
now include the use of gamma irradiation due to the potential
risks of toxic residues remaining after ethylene oxide sterilization (16).
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EXPERIMENTAL STUDIES
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Animal Investigations
Viljanen et al. (14) studied the changes that occur in bones
after experimental osteotomies werefixed with absorbable 4.5mm SR-PLLA screwsand 4.5-mm metallic screwsthe distal
femur in rabbits. They found that at 36 weeks, there was a
significantlyincreased amountofexternal calluswith
themetallic fixation groupwhencomparedwiththe
SR-PLLA group. However,cortical bone mineral density was
decreased in the metallic fixation group at both 6and 36
weeks. Magnetic resonanceimagings showed edema
surrounding the screws in both groups, however,the size of
theedematouszones wassignificantlydecreasedinthe
SR-PLLA group. The authors felt that the SR-PLLA fixation
method resulted in morerapid and improved healing due to
the physiologic elasticity of these implants when compared
with the metal screws. The resorbable implants appeared to
prevent stress protection atrophy and weakening of the fixed
bone secondary to osteoporosis.
Joukainen et al. (11) studied the strength retention of 2.0mm SR-PLA70/30 rodsand fixationpropertiesofthese
implants in rat distal femur osteotomies. In addition, 70 absorbable rods wereimplanted into the dorsal subcutaneous tissue of
16 rats and three point bending and shear tests wereperformed
after these animals were killed. At 52 weeks, the shear strength
and flexural modulus was 41% of their initial value and the
flexural strength was 43% of its initial value. Osteotomies in the
distal femur werefixed with rods in 39 rats. Macroscopic and
X-ray analysis showed that 23 out of 32 subjects (72%) have
solid union at the osteotomy site. These authors felt that the
mechanical strength and fixation properties of the resorbable
rods were adequate for fixation of osteotomies in cancellous
bone in rats.
FIGURE 1 Two different sized plates and abioresorbable screw from
the ReUnite e set(EBI, Parisippany,New Jersey,U.S.A.).These
implants are manufactured from acopolymer of 82%
L -lactic acid and
18% glycolic acid. Source:Courtesy of John T. Capo, MD.
FIGURE 2 AReUnite screw and smooth pin. The screw head attachment is seen. This hex-shapedend fits into the screwdriver and is sheared
offwhen the screw is fully seated. Source:Courtesy of John T. Capo, MD.
FIGURE 3 The ReUnite set contains avariety of metal drill bits, taps,
implant insertion instruments, and depth gauges.
20
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Kavanaghetal.
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Human Investigations
Pihlajamaki et al. (18) examined the use of SR-PLLA absorbable pins in thefixation of fractures and osteotomies in
humans. They reviewed 27 patients with fractures or osteotomies that were treatedwith internal fixationusing
bioabsorbable pins.Patientshad smallfragmentfractures
and osteotomies of the hand, foot, elbow,and patella. The
authors used 1.5- or 2.0-mm cylindrical rods composed of
SR-PLLA. There werenowound infections or inflammatory
foreignbody reactions noted. No redisplacement occurred in
any of the patients and the materials were absorbed within
two years. Computed tomography scans wereobtained in
three patients at 15 and 37 months and showed that the pins
werenolonger visible but no new bone had formed within
the drilled channels.
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INDICATIONS
Although the literature has yet to clearly elucidate definitive
indications for the use of bioabsorbable implants, there are
specific timeswhenthe use of theseimplants canbe
beneficial. In the hand and wrist, there is little soft tissue
coverage andthe use of abulky metalimplant canbe
problematic. Using resorbable implants in these cases could
be advantageous to minimize final hardware prominence
and to avoid asecond operation to remove these implants
(1,3,19–26). When metal implants are removed, unfilled holes
can provide astress riser for afracture. As bioabsorbable
implants slowly degrade, the surrounding bone is able to fill
in such defects.
The use of metal implants around the tendons and joints in
the hands and wrist can also pose potential problems. Bioresorbable implants pose less of aproblem with encroachment
on atendon or the joint capsule. If asmall portion of the implant
is within the joint or impinging on atendon, this difficulty will
be alleviated as the implant resorbs.
There are also other times in which abioabsorbable implant
is notanappropriate choice. If thepatienthas an active
infection, the use of any type of implant should be avoided as
this would provideanidus for persistent infection. At this point
in time, complex articular fractures that need rigid fixation in
order to prevent displacement and to ensure anatomic articular
alignment, should be fixed with the more traditional metal
implants (5).
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SPECIFIC IMPLANTS USED IN FIXATION OF
FRACTURES
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Metacarpal Shaft Fractures
Surgical Technique
The typical injury is usually adisplaced index or middle
finger metacarpal fracture in aslender and young individual
(Fig. 4). Anesthesia can be performed locally,via regional
blockade, or general anesthesia as per surgeon preference.
The hand is prepped and draped in standard fashion. A
longitudinal dorsal incision should be made over the metacarpal fracturesite. The extensor tendon is protected and
retracted and the juncturae tendinae are divided if necessary.
Theoverlying periosteum and interosseusmuscle are
elevated as aflap. The fracture surfaces are identified and
fracture ends prepared in standard fashion(Fig. 5A). To
improve fracture stability while still keeping the hardware
low-profile, we often prefer to place ametal interfragmentary
screw first (Fig. 5B). This also makes placement of the plate
much easier.Abioabsorbable plate is applied dorsally to the
tension side of the metacarpal. The ReUnitee (EBI, Parisippany,New Jersey,U.S.A.) sethas malleabletemplates
availabletosizeand assess the contour of the necessary
plate (Fig. 6). The screw holes are drilled and the threads
are tapped with metal instruments. The bioabsorbable screws
are individually wrapped sterile and come attached to an
insertion rod fixed to the head. They are inserted with the
appropriate screw driver and the insertion rodissheared off
(A)
(B)
FIGURE 4 ( A )Anterior–posterior radiographdemonstrating asecond
metacarpal shaft fracture with shortening and displacement. ( B )Lateral
view shows unacceptable angulation of the fracture. Source: Courtesy of
John T. Capo, MD.
Bioabsorbable Implants in Hand and Wrist Surgery
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21
as the screw is seated (Fig. 7). The final few turns typically
achieve asolid bite, but care must be taken not to overtighten
the screws as the head can be sheared off. The heads may be
flattened somewhat with an electrocaughteryinstrument
included in the set that melts the material. The periosteum
and muscle fascia are closed over the plates to avoid any
early tendon impingement (Fig. 8).
Outcomes
Waris et al. (22) compared bioabsorbable miniplating versus
metallic fixation for metacarpal fractures, using fresh frozen
second metacarpals from cadavers. He tested threepoint
bendingand torsional loadingafter transverse osteotomies
were fixed with avariety of methods, includingSR-PLLAPGA80/20 plating, SR-poly-
L / DL-lactide 70/30plating,
(A)
(B)
FIGURE 5 ( A )Exposure of amid-shaft second
metacarpal fracturethroughalongitudinal
incision. The periosteum and muscle fascia are
elevated as aflap. The patient is a17-year-old
boy andthisishis dominant hand. ( B )The
fracture is first stabilized with atenaculum and
then provisionallyfixedwit h1.3-mmtitanium
screw in alag fashion. Source:Courtesyof
John T. Capo, MD.
FIGURE 6 Atrialing template is placed over
the dorsum of the metacarpal to approximate
the length of theplaterequired. Source:
Courtesy of John T. Capo, MD.
22&Kavanaghetal.
titanium plating, and Kirschner (K)-wirefixation. In apex dorsal
and palmar bending, dorsal SR-PLLA-PGA 80/20 plating, and
SR-poly-
L / DL-lactide 70/30 plating providedstability com-
parable with dorsal titanium 1.7-mm plating. The rigidity and
maximum bending moment of 2.0-mm dorsal bioabsorbable
plates werehigher than those of K-wires. Overall, he found that
low profile SR-PLLA-PGA and SR-poly-
L / DL-lactide miniplates
providesatisfactorybiomechanicalstability formetacarpal
fixation.
&
PHALANGEAL FRACTURES AND
INTERPHALANGEAL JOINT ARTHRODESIS
&
Surgical Technique
Fracture Fixation
The phalangeal fractures are reduced in astandard fashion and
percutaneous pinning is typically performed. With most bioabsorbable pins, ahole needs to be first drilled with ametallic pin.
The resorbable rodisthenplacedintothistract with an
insertion device. The insertion device pushes the rod along
the hole drilled by the K-wire. This requires rigid stability of the
fracturefragments to avoid malalignment of the K-wire path.
This at times can be difficult. Recently anew resorbable pin,
Trim-It Drill Pine (Acumed, Beaverton, Oregon, U.S.A.) has
been introduced that avoids this. The pin has an attached metal
tip that allows it to be drilled directly into the bone. The metal
tip can be cut offonthe far side of the bone when possible or can
be left on theinnerside of themedullarycanal to
avoid migration.
&
Arthrodesis
The distal interphalangeal joint is approached through adorsal
Y- or H-type incision. The extensor tendon is divided and the
collateralligamentsare elevated. The articular surfaces are
removed with arongeur.Next, the intramedullary canals of the
distal and proximal phalanxes are drilled utilizing adrill-bit that
is 0.5-mm larger in diameter than the bioabsorbable rod. This is
followed by reaming the canals to the size of the implant. The
bioabsorbable rod is inserted anterograde into the distal phalanx
medullary space. The distal phalanx and intramedullary placed
rodisthenreduced to themiddle phalanx in aretrograde
fashion. The extensor tendon, collateral ligaments, and skin are
then sutured in standard fashion and the finger is splinted.
&
Outcomes
Jensen and Jensen (26) investigated poly-p -dioxanone (PPD)
pins in phalangeal fracture fixation, arthodesis, and osteotomies
versus standard K-wires. Their case series compared 11 patients
with biodegradable pindevices [fouropenreductionand
internal fixation (ORIF), five arthrodeses, and two osteotomies]
to 12 patients (three ORIF and nine arthrodeses)instrumented
with K-wires followed over six months. In the fracture-fixation
group, the authors reported an earlier return to normal range of
motion usingthe resorbableimplants. Oneout of thefour
patients with PPD pins required reoperation secondary to loss
of fixation. Allofthe K-wire fracture fixationsrequired
additional procedures for hardware removal.
Patients treated with PPD arthodeses had two failures of
fusion (40%)and onerequiredre-fusion while thesecond
received an amputation. This is greater than the frequency of
failed fusions noted in the K-wire group (22%). One pin tract
infection was noted in the PPD arthodesis group versus two pin
tractinfectionsinthe K-wire group. Thirteenadditional
procedures wereneeded to remove the K-wires. This study is
promising, but it contains small patient numbers and had a
follow-up time of only six months.
Interphalangeal jointarthrodesis utilizingPLLA rods
was investigated by Arata and colleagues (27). This case series
of 15 distal interphalangeal joints andone interphalangeal
joint of thethumb hadafollowupoftwo to 25 months.
Successful fusion was noted in all joints by eight weeks. Two
patientsdevelopedpainlesslocalizedswelling. No cases of
infection, nonunion,ordeformitywerenoted. Theauthors
concluded that PLLA rods can be safely used for interphalangeal fusions.
&
SCAPHOID FRACTURES AND NONUNIONS
&
Surgical Technique
The following surgical technique will focus on percutaneous
fixation of scaphoid fracturesfromavolar approach. For more
comminuted or displaced fractures, an open technique is more
appropriate. The patient is positioned supine and the upper
extremityisplaced on astandard handtable andaminifluoroscopy machine is usedtovisualize the scaphoid.
The wrist is placed over asmall towel bump to induce wrist
extension.The volarretrograde approachisour preferred
entrysite forpercutaneousfixationofscaphoidfractures.
FIGURE 7 The resorbable implant is placed
dorsally and fixed proximally and distally with
twoscrews. Sou rce :Cou rt esyofJohnT.
Capo, MD.
Bioabsorbable Implants in Hand and Wrist Surgery
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23