Arthrodiastasis of the Ankle joint: An Alternative to Fusion
Arthrodiastasis of the Ankle joint: An Alternative to Fusion
Arthrodiastasis of the Ankle joint: An Alternative to Fusion
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CHAPTER 6ARTHRODIASTASIS OF TFIE ANKLE JOINT,AN ALTERNATIVE TO FUSIONGeorge R.W<strong>to</strong>, DPMLeomard Talarico, DPMINTRODUCTIONPresently, we know <strong>of</strong> two major forms <strong>of</strong>osteoarthritis, both <strong>of</strong> which can be severelydisabling. In primary osteoafihritis <strong>the</strong> cause isgenerally unknown, and in secondary osteoafihdtis<strong>the</strong> cause is generally ffaumatic in origin. Both formspresent with similar clinical symp<strong>to</strong>ms, whichinclude pain, decreased range <strong>of</strong> motion, andswelling. Radiologically, <strong>the</strong>re is a decrease in <strong>the</strong><strong>joint</strong> space, and presence <strong>of</strong> osteoph),tes andsubchondral cysts with sclerosis <strong>of</strong> subchondralbone. Extracel1ularly, afiicular cafiilage has twoprinciple components. Collagen that gives it shapeand tensile strength and proteoglycans, that givearlicular cafiilage its compressive propefties. Inosteoafihritis <strong>the</strong>re is an imbalance between <strong>the</strong>syn<strong>the</strong>sis and <strong>the</strong> release <strong>of</strong> <strong>the</strong>se two components.This leads <strong>to</strong> both a disruption <strong>of</strong> <strong>the</strong> collagennetwork and a loss <strong>of</strong> proteoglycans. Thesebiochemical changes that occur appear <strong>to</strong> have nodiagnostic clinical correlation, especially in <strong>the</strong> earlystages <strong>of</strong> <strong>the</strong> disease process.Treatment <strong>of</strong> osteoarthritis has includedantiinflamma<strong>to</strong>ry medications and exercise. Also,arthroscopic <strong>joint</strong> lavage coupled with subchondralbone drilling has been used. None <strong>of</strong> <strong>the</strong>semodalities have proven <strong>to</strong> provide significantimprovement in symp<strong>to</strong>ms, 1et alone a cure. Theultimate end for patients with osteoarthritis iscomplete destmction <strong>of</strong> <strong>the</strong> articular cafiilage withresultant need for afihrodesis or arthroplasty <strong>of</strong> <strong>the</strong>affected <strong>joint</strong>.THE PROCEDURERecently, five patients who were candidates forafihrodesis <strong>of</strong> <strong>the</strong> tibiotalar <strong>joint</strong> as a result <strong>of</strong> ei<strong>the</strong>rprimary or secondary arthritis were <strong>of</strong>fered ano<strong>the</strong>rtreatment option, diastasis <strong>of</strong> <strong>the</strong> tibiotalar iointusing external fixation. The goal <strong>of</strong> <strong>the</strong> surgery was<strong>to</strong> eliminate mechanical stress on <strong>the</strong> ankle <strong>joint</strong> bypreventing contact between <strong>the</strong> tibia and <strong>the</strong> talus.It should be noted that adjunctively, arthroscopiclavage cor-rld be performed at <strong>the</strong> same time asframe application.The primary reason that this particularprocedure was chosen is because it has beenreported that when intermittent hydrostatic pressureis applied <strong>to</strong> human osteoarthritic catilage in tissueculture <strong>the</strong> result was a significant increase in <strong>the</strong>syn<strong>the</strong>sis <strong>of</strong> proteoglycans. Recall that proteoglycansprovide arlicular cafiilage with its compressivepropefiies. Thus, hypo<strong>the</strong>tically, when intermittentintraarticular hydrostatic pressure is applied <strong>to</strong>human articular cartilage, in <strong>the</strong> absence <strong>of</strong> mechanicalstress, <strong>the</strong> result could be a reparative activity by<strong>the</strong> chondroq,tes in <strong>the</strong> osteoafihritic cartilage. Asecondary reason for making this choice is that thisprocedure is not <strong>joint</strong> destructive.Under general anes<strong>the</strong>sia, one <strong>of</strong> two types <strong>of</strong>external fkation was applied. These included ei<strong>the</strong>r<strong>the</strong> Ilizarov ring apparatus or a mono lateral flxa<strong>to</strong>r.Application <strong>of</strong> <strong>the</strong> llizarov apparatus involved tw-oleg rings applied <strong>to</strong> <strong>the</strong> tibia and attached withscrew-threaded rods. A footplate was <strong>the</strong>n appliedwith two wires in <strong>the</strong> calcaneus and two wiresthrough <strong>the</strong> metatarsals. The footplate was <strong>the</strong>nfked <strong>to</strong> <strong>the</strong> 1eg rings with two hinged rods and onescrew-threaded rod posteriorly <strong>to</strong> initially preventankle motion for <strong>the</strong> first two weeks pos<strong>to</strong>peratively.The mono Tateral fixa<strong>to</strong>r involved placement <strong>of</strong> halfpins in<strong>to</strong> <strong>the</strong> tibia, talus and calcaneus. Fixation <strong>of</strong><strong>the</strong> ankle <strong>joint</strong> was also maintained for <strong>the</strong> first twoweeks pos<strong>to</strong>peratively.Distraction was achieved on <strong>the</strong> operating tableand was <strong>the</strong>n carried out until approximately 5mm<strong>of</strong> <strong>joint</strong> space was achieved. The patients wereencouraged <strong>to</strong> ambulate <strong>to</strong> <strong>to</strong>lerance on <strong>the</strong> firstpos<strong>to</strong>perative day. Load bearing on <strong>the</strong> distracted<strong>joint</strong> was essential in order for <strong>the</strong>re <strong>to</strong> be anincrease in <strong>the</strong> intraarticular hydrostatic pressure.After two weeks, ankle <strong>joint</strong> motion was allowedwith <strong>the</strong> use <strong>of</strong> hinges. Exercises for range <strong>of</strong> motionwere performed and ambulation was encouraged.During <strong>the</strong> treatment period with ei<strong>the</strong>r fixa<strong>to</strong>r <strong>the</strong>re
CHAPTER 53tinstances <strong>the</strong> author Llses a Jones compressiondressing. This type <strong>of</strong> cast is usecl during rhe initialpos<strong>to</strong>perative phase as it provides a measure <strong>of</strong>protection for <strong>the</strong> external frame. Although this isnot a necessity, it does generally provide a certainlevel <strong>of</strong> comf<strong>of</strong>i and security for <strong>the</strong> patient tintil<strong>the</strong>y can become adfusted <strong>to</strong> <strong>the</strong> presence <strong>of</strong> <strong>the</strong>frame. The cast is usually discontinued within <strong>the</strong>first week or so after <strong>the</strong> surgery.In some patients <strong>the</strong> distraction process willresr-r1t in deviation <strong>of</strong> <strong>the</strong> <strong>to</strong>e due <strong>to</strong> <strong>the</strong> tension thatis placecl on <strong>the</strong> flexor or extensor tendons. <strong>An</strong>umber <strong>of</strong> authors have described inserting aKirschner-wire in<strong>to</strong> <strong>the</strong> associated digit, and at timesacross <strong>the</strong> metatarsophalangeal <strong>joint</strong> as it is believedby some that <strong>the</strong> use <strong>of</strong> <strong>the</strong> wire will tend tcrmediate this effect. The author has not found that thisis a problem, and a pin is not used routinely in <strong>the</strong>associated <strong>to</strong>e. However, <strong>the</strong>re have been somepatients where <strong>the</strong> <strong>to</strong>e required some additionalsplintage with tape during <strong>the</strong> leng<strong>the</strong>ning process <strong>to</strong>ovefcome this type <strong>of</strong> problem.Pos<strong>to</strong>perative CareAs noted above, <strong>the</strong> patient is usually placed in<strong>to</strong> aJones compression cast initially. The patient is maintainednonweightbearing until it is deemed thatsufficient leng<strong>the</strong>ning and healing have occurred. Attwo weeks after surgery <strong>the</strong> patient will begin <strong>the</strong>distraction process, turning <strong>the</strong> apparatLls onequaftertllrn every six hours. Racliographs are <strong>the</strong>nmade periodically <strong>to</strong> assess <strong>the</strong> amount <strong>of</strong> leng<strong>the</strong>ningwhich has been achieved, and once this is felt <strong>to</strong>be sufficient, <strong>the</strong> patient is instructed <strong>to</strong> discontinue<strong>the</strong> distraction process. Should <strong>the</strong> metatarsal beovedeng<strong>the</strong>necl, <strong>the</strong> reverse process can beemployed, that being sh<strong>of</strong>iening <strong>of</strong> <strong>the</strong> metatarsaluntil a sufficient length has been achieved.Afterwards, <strong>the</strong> patient is evaluated periodicallywith radiographs <strong>to</strong> cletermine when <strong>the</strong>re has beensufficient healing for initial weightbearing. Once thisinterval has been achieved. <strong>the</strong> author will allow <strong>the</strong>patient <strong>to</strong> begin initial weightbearing with rhe pinsand frame in place. It is felt that this provides somemeasure <strong>of</strong> protection against excessive weightbearingforces on <strong>the</strong> newly leng<strong>the</strong>ned area <strong>of</strong>bone. The author has seen some patients wheresagittal plane deformity has developed in <strong>the</strong>metatarsal once weightbezrring was instituted. Inthose circumstances, it was usually due <strong>to</strong> <strong>the</strong> factthat <strong>the</strong> frame was removed prior <strong>to</strong> <strong>the</strong> institution<strong>of</strong> weightbearing.The patient is <strong>the</strong>n re-evaluated two weeks later,at which time <strong>the</strong> distal and proximal pins areremoved from <strong>the</strong> erlernal fka<strong>to</strong>r. Weightbearingcontinues for an additional two weeks with only two<strong>of</strong> <strong>the</strong> remaining pins in p1ace. At that time, <strong>the</strong>remaining pins and exlernal fxa<strong>to</strong>r are removed. Thisallows <strong>the</strong> osseous tissues <strong>to</strong> adapt <strong>to</strong> weight-bearingstress over time, reducing <strong>the</strong> likelihood <strong>of</strong> plasticdeformation <strong>of</strong> <strong>the</strong> more immature bone substance.The greatest drawback <strong>to</strong> this type <strong>of</strong> procedureis <strong>the</strong> lengthy period <strong>of</strong> nonweightbearing thatmay be required in some patients. On average, ittakes abor-rt three months before patients are ready<strong>to</strong> begin ful1 weight-bearing without <strong>the</strong> externalfixa<strong>to</strong>r when a lesser metatarsal has been addressed.How-ever, patients undergoing surgery on <strong>the</strong> firstmetatarsal generally require a much more lengthyinterval <strong>of</strong> nonweightbearing, sometimes extendingup <strong>to</strong> sk months.ComplicationsPotential complications with this approach are generallyminor and usually will consist <strong>of</strong> some type <strong>of</strong>digital deformity due <strong>to</strong> <strong>the</strong> altered tension on <strong>the</strong>tendons. Mild cases <strong>of</strong> dorsal nelve entrapment havealso been encountered, but <strong>the</strong>se have respondedwell <strong>to</strong> locai injections <strong>of</strong> corticosteroid.Fufihermore, in some patients <strong>the</strong> degree <strong>of</strong> scarringin <strong>the</strong> skin can be objectionable. This is due <strong>to</strong> <strong>the</strong>fact that linear tension is being applied <strong>to</strong> <strong>the</strong> scarduring <strong>the</strong> initial healing interva1. Therefore, <strong>the</strong>author attempts <strong>to</strong> warn all patients prior <strong>to</strong> undergoing<strong>the</strong> procedure that this may be a fac<strong>to</strong>r aftersurgery. This may be particularly important whenpatients are undergoing <strong>the</strong> procedure primarily forcosmetic reasons. However, <strong>the</strong> scar can ceflainlybe excised and primarily closed at a later time,rendering a more appealing scar for <strong>the</strong> foot.ConclusionOverali callous distraction is a viable alternative in aselect patient group <strong>to</strong> address sh<strong>of</strong>iening <strong>of</strong> ametatarsal. However, <strong>the</strong> author's preference in mostsituations is <strong>to</strong> employ a sagittal Z osteo<strong>to</strong>my, iffeasible. This approach is simple, effective, andinvolves less recovery time than if callous distractionor bone grafting is required. None<strong>the</strong>less, callousdistraction is effective, and may be preferable inmost situations where previous infection has beena problem.
CHAPTER 6 33was radiographic evidence <strong>of</strong> increased <strong>joint</strong> spacewith <strong>the</strong> patient fuli weight bearing. The assumptionwas made that <strong>the</strong> weight bearing surfaces <strong>of</strong> <strong>the</strong>tibia and <strong>the</strong> talus did not come in<strong>to</strong> contact during<strong>the</strong> time <strong>of</strong> distraction. Total time <strong>of</strong> distraction wasbetween five and sk weeks. The frame was <strong>the</strong>nremoved and <strong>the</strong> patients continued with physical<strong>the</strong>rapy and ambulation <strong>to</strong> <strong>to</strong>lerance.The resultant effect <strong>of</strong> diastasis <strong>of</strong> <strong>the</strong> tibiotalar<strong>joint</strong> is an elimination <strong>of</strong> normal mechanical stressplaced on <strong>the</strong> articular cartilage due <strong>to</strong> <strong>the</strong> absence<strong>of</strong> contact between <strong>the</strong> <strong>joint</strong> surfaces and aLintermittent increase in intraarticular hydrostaticpressure. As previously mentioned, in tissue culture,cartilage displays reparative activity when placed in<strong>the</strong>se conditions. The primary reparative activitynoted was that <strong>of</strong> increased proteoglycan productionby more than 50%. It can be speculated that thisincrease in syn<strong>the</strong>sis <strong>of</strong> proteoglycans may be <strong>the</strong>reason for <strong>the</strong> increase in <strong>joint</strong> space. It has alsobeen suggested that by distraction <strong>of</strong> <strong>the</strong> <strong>joint</strong> <strong>the</strong>reis a subsequent increase in <strong>the</strong> circulation <strong>of</strong>synovial fluid that provides nutrition <strong>to</strong> <strong>the</strong> afiicularcartilage. For whatever reason, diastasis <strong>of</strong> <strong>the</strong> ankle<strong>joint</strong>, with elimination <strong>of</strong> mechanical stress, leads<strong>to</strong> improvement in <strong>the</strong> articular cafiilage and areduction <strong>of</strong> <strong>the</strong> symp<strong>to</strong>ms <strong>of</strong> osteoarthritis.The purpose <strong>of</strong> performing diastasis <strong>of</strong> <strong>the</strong>tibiotalar <strong>joint</strong> in patients with severe osteoarthritiswas <strong>to</strong> delay <strong>the</strong> need for arthrodesis. Thus far, fivepatients have been treated in this manner. Clinicallyall patients continlle <strong>to</strong> experience a recluction inpain, an increase in <strong>joint</strong> range <strong>of</strong> motion, andradiographic appearance <strong>of</strong> <strong>joint</strong> space. \[ith thispositive clinical evidence it appears that ankle iointdiastasis, with ei<strong>the</strong>r <strong>the</strong> Ilizarov apparatus or amonolateral fixa<strong>to</strong>r, may deiay <strong>the</strong> need forarthroclesis in patients with primary or secondaryosteoarthritis.Figure 1. Preoperative AP radiograph <strong>of</strong> <strong>the</strong>ankleFigure 2lramePost distraction AP racliograph srith
CHAPTER 6Figllre .1. Pos<strong>to</strong>peratile latcral vie\\. <strong>of</strong> extcrnal fka<strong>to</strong>rFignle J. Pos<strong>to</strong>pcrlLtive clinical At, r-ies <strong>of</strong> crter.nal flra<strong>to</strong>r.Figue 6. Pos<strong>to</strong>perative latelal vics- <strong>of</strong> ankle at 1 ve.LrFigure 5. Pos<strong>to</strong>perati\.e A1) r':rcliograph <strong>of</strong> ..rnkle :rt1 ycar'.