INTRODUCTION

First metatarsophalangeal joint implant arthroplastyhas been performed at Doctors Hospital for the past 30

years. ln certain instances the silastic implants have beenvery successful in providing Breater pain free motion ofthe joint (MPJ), and in turn, allowing the patient to walkwith less difficulty. Joint implants are generally con-sidered as spacers and do not act functionally. They do,however, increase the range of motion substantially inmost cases.

What are the specific indications, contraindications,and complications of the hemi and the total silasticimplants? In what situations should the surgeon choosea hemi-implant over a total implant? We will attempt toanswer these questions as well as present the planningand preliminary results of a retrospective study compar-ing the two types of first metatarsophalangeal jointimplants.

PURPOSE

The purpose of this study is to discuss the factors thatcontribute to successful implant arthroplasty of the firstMPJ. The inherent advantages of the hemi over the totalimplant is presented. The specific purpose is to test thevalidity of the assumption that the implant functionsmainly as a joint spacer and must not be depended onto accomplish restoration of motion or correction ofdeformity.

The study is divided into two phases and the paper willpresent the preliminary results. Phase one is a physician'ssurvey to demonstrate the experiences of surgeons atthe Podiatry lnstitute. Each physician's responses andcomments were confidential and were used in combina-tion with other responses for statistical purposes only.The preliminary results of this study is included herein.

Phase two is a ten year retrospective study consistingof a random sampling of 150 patients out of over 1,000

patients who underwent implant arthroplasty of the firstMPJ. The preliminary results will be presented at theAtlanta meeting in the spring of 1989 as a basis for fur-ther investigation.

IMPLANTS: TOTAL VS. HEMI

fames [. Bouchard, D.P.M.Alfred f. Phillips, D.P.M.

HISTORY

ln order to better appreciate first metatarsophalangealjoint implant arthroplasty a brief historical review of theliterature pertaining to implant indications and their use

is necessary.

First metatarsophalangeal joint implants are indicatedin a variety of situations. lmplants are indicated whenthere are clinical or radiological signs of degenerationof joint surfaces of either the base of the proximalphalanx or the head of the first metatarsal. This canobviously occur in hallux rigidus, hallux valgus, halluxvarus/ rheumatoid arthritis, osteoarthritis, and any othe.r

disease or traumatic process capable of damaging jointcartilage.

Many attempts to correct the arthritic joint have beencited in the literature. Heubach in1897 first introducedthe idea of relaxing the joint impingement by resection

of all or part of the first metatarsophalangeal joint (1).

ln 1904, Keller introduced a procedure which is stillpopular today. He described the resection of a part ofthe base of the proximal phalanx (2). Mayo and Stonehave described procedures that resect the head of thefirst metatarsal. These procedures have been com-plicated by shortening of the hallux, instability of thehallux, lesser metatarsalgia, and improper jointalignment.

lmplants were first introduced as treatment for arthriticfirst metatarsophalangeal joint deformities (halluxrigidus, hallux valgus, hallux varus) in 1951 when Endlerintroduced an acrylic implant to be placed in the base

of the proximal phalanx as an adjunct to a Kellerprocedure (3). In 1956 Sieffert placed a nylon spacerbetween the base of the proximal phalanx and the firstmetatarsal head (4). These and other attempts failed dueto bioincompatibility.

ln 1967 Swanson introduced silicone implants to be

used at the metacarpophalangeal joints of the hand andthe first metatarsophalangeal joints of the foot. Thesilicone is a high performance medical grade specifical-ly developed for use as flexible joint implants (5). Siliconeis an inert material which had proven in clinical studiesto be biocompatible.

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The hemi-implant introduced by Swanson serves as aninterpositional spacer to be used as an adjunct to theKeller arthroplasty procedure. lt serves as the base of theproximal phalanx and consists of two parts: base (collar)and the medullary stem (Fig. 1). The base is ovoid inshape, the width (medial to lateral) being greater thanits height (dorsal to plantar). The intra-articular surfaceis concave to fit the head of the first metatarsal. Theimplant is produced by Dow Corning Co. and ismarketed in five sizes. The Swanson hemi-implant is themost commonly used hemi-implant at our Institution andwill therefore be the subject of our retrospective study.

Weil modified the Swanson hemi-implant in the late1970's when he accounted for an abnormal proximal ar-ticular set angle. A 15 degree lateral flare was added tothe implant to accommodate for a resultant lateral gapwhen the toe was straightened.

Swanson introduced a double stemmed silicone im-plant in 1977 tor those joints which had severe arthriticchanges in the head of the first metatarsal (Fig.2). Theimplant is also produced by Dow Corning and ismarketed in eight sizes. There is no angulation in eitherthe transverse or sagittal plane. The implant allows fordorsiflexion with a U-shaped hinge. This implant is alsoused quite extensively at our Institution.

Attempts have been made to improve on the hemi andtotal silastic implants. Sutter introduced the LaPorta andLawrence total implant designs. These appear asmodified versions of the Swanson total implant whichincrease the range of motion and accommodate fordeforming forces by angulating the stems in thetransverse and sagittal planes. Swanson claimed thatthere was 60 degrees of motion at the metatar-sophalangeal joint after total joint implantation. Studiesperformed by LaPorta and Barry have indicated that mo-tion is somewhat less.

LaPorta and Lawrence report ranges of motion of 60

degrees or greater. Their implants consist of an H-shapedhinge instead of the U-shaped. This purports to allow forgreater range of motion. Both of the designs are angled15 degrees in the sagittal plane thus accomodating forthe first metatarsal declination angle. The LaPorta implantis marketed in a right, Ieft, and neutraldesign, deviatingthe left and the right by ten degrees in the transverseplane. The Lawrence implant is only produced in aneutral design. In the Lawrence design the hinge iselongated dorsally and angulated inferiorly so that theinsertion of the flexor hallucis brevis remains intact. Heallowed for angular cutting of the phalangeal base topreserve the tendinous insertion (6).

INDICATIONS FORIMPTANT ARTHROPLASTY

lmplant arthroplasty is indicated when there is signifi-cant arthritic deterioration and joint narrowing at the firstmetatarsophalangealjoint and in which instance a Kellerprocedure is an option. These circumstances can be pre-sent in hallux limitus or rigidus, hallux abducto valgus,or hallux varus deformity. Any situation which results ininstability or painful restriction of motion may providean indication. Severe subluxation and lateral deviationof the proximal phalanx with subchondral-bone changesare also good indications for joint implant arthroplasty.Painful range of motion with joint crepitus noted onphysical exam reinforce the need for implants.

Hemi implants are indicated when there is significantdegenerative change on the base of the proximal phalanxand mild change on the head of the first metatarsal. Thiscan be appreciated in Figure 3. There are many instanceswhen radiologic evaluation indicates significantdegeneration of the metatarsal head. Yet, after resectionof osteophytic lipping and cleaning the joint of debris,the head of the metatarsal may show only milddegenerative change. ln these situations hemi implantsare appropriate.

Total implants are indicated in those instances wherethere is significant subchondral bone degeneration onboth sides of the joint as can be seen in Figu re 4. At ou rInstitution totalsilastic implants are used in combinationwith a pan metatarsal head resection so that the metatar-sal parabola is maintained.

GOATS OF SUCCESSFUTIMPTANT ARTHROPLASTY

The primary goal is relief of pain. lmplant arthroplastycan accomplish this by removal of the joint and replace-ment by a spacer to prevent shortening of the hallux.

Motion is restored to the joint as previously men-tioned. Total hinge implants provide greater motion as

compared to hemi implants.

It is important to reduce any deformity that is present.In some instances additional osseous correction isnecessary to reduce the deforming force. This mayinvolve such combinations of surgery as a base wedgeosteotomy along with a total first metatarsophalangealjoint implant arthroplasty.

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Fig. 1. Swanson hemi silicone implant produced by Dow Corning Phar-

maceutical Co.

Fig. 2. Swanson double stemmed silicone implant producedCorning Pharmaceutical Co.

by Dow

Fig. 3. First metatarsophalangeal joint arthroplasty with insertion ofSwanson silastic hemi implant. A. Preoperative and B. Postoperative

x-rays.

CONTRAINDICATIONS FORIMPHNT ARTHROPLASTY

There are several contraindications to implantarthroplasty which must be considered. Peripheralneuropathy prevents adequate proprioception and painsensation which are desirable for successful implantarthroplasty. The performance of implant procedures insuch patients has led to destruction of the implant andthe joint in a process similar to that seen in a charcotjoint (6).

The procedures are contraindicated in osteoporoticbone for obvious reasons. The soft bone in these patientsmay not support an implant and bone erosion or collapseof the joint can result (6).

Historically implant procedures have been of ques-tionable value in young individuals with a high activitylevel. Alternative joint sparing procedures should be at-

tempted where possible. ln addition, the proceduresshould not be performed in patients with an activegrowth center at the head of the metatarsal and base ofthe proximal phalanx. This would obviously result in

stunting growth of the first ray (6).

Previous history of infection at the joint is also a con-traindication. Recent evidence supports reimplantationwith the appropriate selection of cases and with an-

tibiotic coverage. This, however, has been largely ob-served in large joints (6).

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Fig. 4. First metatarsophalangeal joint arthroplasty with insertion ofSwanson silastic total implant. A. Preoperative and B. postoperativex-rays.

COMPTICATIONS

A Variety of complications have been reported withsilastic implants in general and specifically with hemi andtotal implant arthroplasty. Vanore et al classified the com-plications into two categories: intrinsic and extrinsic.

lntrinsic failure of the implant refers to the failure ofinherent physical properties of the implant itself suchas fatigue fractures.

Extrinsic failure of the implant refers to those problemsassociated with the tampering or injudicious use of theimplant (6). This is divided into alignment abnormalities,adjacent bone abnormalities (aseptic necrosis, ectopicbone formation), soft tissue abnormalities (reactions tosilicone), and biomechanical joint failure (surgical tech-nique error and failure inherent to the joint arthroplasty)(7). The complications of biomechanical joint failurerelate to the discussion of complications associated withhemi vs. total implants.

Hallux extensus is a relatively common complicationand is observed in both the hemi and total silastic im-plants. Caneva et al reported hallux extensus as the mostfrequently seen complication (8). lnadequate repair ofthe insertion of flexor hallucis brevis, laceration of flex-

or hallucis longus tendon, and extensor hallucis contrac-ture predispose the patient to this complication.

Complications associated most specifically with hemiimplants stem from the transverse instability inherent tothis arthroplastic procedure. They are most commonlyobserved when using the implant arthroplasty to correcthallux valgus. If the deforming forces (intermetatarsalangle, proximal articular set angle) have not beenneutralized, bending forces are created. lf the in-termetatarsal (lM) angle is excessive stress is created atimplant collar and stem interface which can result indislocation or deformation of the implant. Insertion ofa hemi implant into a joint with an abnormally high prox-imal articular set angle (PASA) creates gaping of thelateral aspect of the joint. This can be observed on x-rayas a lateral gap sign, meaning joint wedging at the lateralaspect of the head of the metatarsal and the articular sur-face of the implant. An aggressive medial capsulorraphycan aggravate this problem.

Compiications most commonly observed with totalsilastic implant primarily stem from excessive resectionof the head of the first metatarsal and instability of thejoint complex if the flexor apparatus is not reattached.Excessive resection of the head of the metatarsal lessensthe purchasing power of first ray and places stress onthe lesser metatarsals causing lesser metatarsalgia.

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SURGICAT PROCEDURES: HEMI ANDTOTAT IMPIANT ARTHROPIASTY

The following surgical procedures should be per-formed with strict attention to anatomical dissection. Thiswill allow the surgeon to systematically dissect the firstmetatarsophalangeal joint and identify pathologicalanatomy. lt will also permit preservation of normalanatomical relationships and prevention of hematomawhich can invite infection.

HEMI IMPIANT ARTHROP1ASTY

Attention is first directed to the dorsomedial aspect ofthe first metatarsophalangeal joint where a curvilinearincision is placed. The incision is deepened through thesuperficial fascia to the deep fascia, being careful tomaintain adequate surgical hemostasis by clamping,coagulating, or ligating bleeders as necessary. At the levelof the deep fascia the natural cleavage plane betweenthe superficial fascia and deep fascia is separated medial-ly, dorsally, and laterally down into the interspace.

Dissection is then directed to the f irst intermetatarsalspace where the deep transverse intermetatarsal liga-ment is transected. The insertion of the adductortendon into the fibular sesamoid and the base of theproximal phalanx is identified. The tendon is sharplydissected from its insertion and tagged for later transfer.The fibular sesamoidal ligament is identified andsuspended with a f reer elevator and transected. Passiverange of motion is then performed to determine whetheradequate plantar lateral release has been accomplished.lf no further release of the fibular sesamoid is warranted,the procedure is continued. However, if further releaseis indicated a fibular sesamoidectomy may be performed.

Attention is then directed to the medial capsule wherean inverted Lshaped capsulotomy is performed extend-ing onto the base of the proximal phalanx. The capsuleand periosteal tissue is dissected from the head of thefirst metatarsal and the base of the proximal phalanx. Theprominent dorsomedial eminence is resected with anosteotome and mallet. Any dorsal osteophytic pro-jections are removed with a rongeur and smoothed witha power burr. The wound is flushed with sterile normalsaline.

Attention is next directed to the base of the proximalphalanx. Subcapsular and subperiosteal dissection is per-formed to f ree all soft tissue attachments. The proximalthird of the base of the proximal phalanx is resected. Themedullary canal is then opened with a probe which is

followed by the appropriate broaches. After preparationof the canal, implant sizers are used to determine theappropriate size. The collar size should be wider than

the cortex to prevent ectopic bone formation around theimplant collar.

Once the appropriate implant size has been deter-mined one drill hole is placed at the plantar aspect ofthe base of the proximal phalanx for reattachment of theflexor hallucis brevis and two drill holes are placed atthe dorsomedial and plantar-medial corners of thephalanx for insertion of the medial capsule. The suturesare then placed but allowed to remain untied.

The plantar suture securing the flexor hallucis brevisto the plantar drill hole is tied. The implant is then placedinto the proximal phalanx and the medial suture drawntight and tied. An adductor tendon transfer is then per-formed if indicated using 2-0 dexon. The remainder ofthe dorsal arm of the capsule is re-approximated with3-0 dexon.

Superficial fascia is usually closed with 40 dexon andskin with 5-0 dexon subcuticular sutures.

TOTAL SILASTIC IMPTANT ARTHROPTASTY

The surgical technique for the insertion of the totalsilastic implant is identical to that of the hemi implantexcept for preparation of the distal end of the metatar-sal. The distal aspect of the metatarsal head is resectedand a canal prepared to receive the proximal stem of theimplant.

The general guidelines recommend a minimal 3 mmresection of bone from the distal aspect of the firstmetatarsal and an 8 mm resection of the base of the prox-imal phalanx. Additional bone may be resected in orderto maintain the appropriate weight-bearing parabola ifindicated (9).

The resection of the base of the proximal phalanx andthe distal head of the first metatarsal is made perpen-dicular to the long axis of the respective bones if theintermetatarsal (lM) angle is relatively low. If the lM angleis increased, the resection must be angled laterally inorder to avoid creating deforming forces. This preventsbending forces on the implant which can result in failureof the implant.

Specific sizers are used for the total implants. Thewidth of the implant chosen depends on the width ofthe base of the proximal phalanx and the head of themetatarsal. The width of the hinge is slightly larger thanthe widest bone.

After the selection of the appropriate implant, it is

placed into the resected joint and the capsule closed as

was described in the preceding procedure. The flexor

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brevis tendon is inserted into the base of the proximal joint demonstrate the experiences of surgeons at thephalanx to help stabilize the first metatarsophalangeal Podiatry lnstitute. Each surgeon was given an oppor-joint and avoid hallux extensus. tunity to comment on factors that are necessary in pro-

RESUrrs [H:,"'"::Ti'Jil, '+iiJ3:'::';]""i,Jii"'11,1*1ixLTThe following responses to questions concerning i'irt

"'g-"on iated their responses and the results that

imprant arthroprasty of the first metatarcrp;t;;;;;i follow are based on percentages'

IMPIANTS OF FTRST METATARSOPHATANGEAT fotNT

1=Stronglyagree 2=Agree 3=Neutral 4=Disagree5 = Strongly disagree NA = Not applicable/don't know

12345NAA. The implant itself in implant arthroplasty functions

mainly as a joint spacer and must not be dependedupon for correction of the deformity . . . . 65% 35% O% O% 0% O%

B. In most cases the hemi implant is preferred over thetotal implant 30o/o 2So/o 10% 30% S% O%

C. More postoperative complications are noted with thetotal implant in comparison to the hemi implant . . . . . . 0% 20% 55% 20% 5% 0%

D. Anatomic dissection and proper tissue handling con-tributes to successful implantation 70% 30% 0% 0o/o O% 0%

E. Muscle-tendon balancing techniques are essential inproviding successful implantation 50o/o 40% S% 5% \Yo 0%

F. Structural realignment of the first metatarsal is impor-tant in establishing motion and obtaining correction ofthe deformity 55% 45% O% O% O% 0%

C. Peripheral neuropathy is a contraindication for implantarthroplasty 35yo 25% 10o/o 3o/o o% 27%

H . Advanced osteoporosis is a contraindication for implantarthroplasty 35% SO% 10% S% O% O%

I . The younger or athletic patient is a contraindication forimplant arthroplasty 25% 45% 25% 5o,/o O% O%

J . Previous history of infection at the implant site is a

contraindication for implant arthroplasty 15% 35% 40% 10% O% 0%

K. lmplant arthroplasty is more commonly performed inthe female patient in comparison to the male patient .. O% 30% 60% 10% O% O%

L. The patients'foot type has a direct relationship to thesuccess of implant arthroplasty 10% 55% 35o/o 0% O% 0%

M.Total implant arthroplasty should be reserved for thosecases where joint destruction is present on the base ofthe proximal phalanx and also the head of the firstmetatarsal 20% 55% 10% 15% O% 0%

N. Hemi implants should not be used when there is mildto moderate degeneration of the head of the firstmetatarsal 0% 400/o 35% 25% 00/o 0%

O. The indications for the hemi implant are the same in-dications as {or the total implant 0,/o 15% 10% 40% 35% O%

P. lmplant failure can be related to the implant designprimarily and not to the surgical indications ortechnique O% 0%o 20% N% 40% O%

Q. Structural realignment of the first metatarsal withmetatarsal osteotomy is essential in obtaining correc-tion of the deformity 20o/o 45o/o 15o/o 20% O% 0%

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The following is a summary of the results of the majori-ty of surgeons surveyed at our Institution.

1 . 100% of the respondents strongly agreed oragreed that the implant itself in implant ar-throplasty functions mainly as a joint spacer andmust not be depended upon for correction ofthe deformity.

2. Over 55% of those surveyed indicated that inmost cases the hemi implant is preferred overthe total implant.

3. 100% strongly agreed or agreed that anatomicdissection and proper tissue handling con-tributes to successful implantation.

4. 90% strongly agreed or agreed that muscle-tendon balancing techniques are essential inproviding successful implantation.

5. 100% strongly agreed or agreed that structuralrealignment of the first metatarsal is importantin establishing motion and obtaining correctionof the deformity.

6. 60% strongly agreed or agreed that peripheralneuropathy is a contraindication for implantarthroplasty.

7. 85% strongly agreed or agreed that advancedosteoporosis is a contraindication for implantarthroplasty.

70% strongly agreed or agreed that the youngeror athletic patient is a contraindication for im-plant arthroplasty.

Only 50% strongly agreed or agreed thatprevious history of infection at the implant siteis a contraindication for implant arthroplasty.

65% strongly agreed or agreed that the patients'foot type has a direct relationship to the successof implant arthroplasty.

75o/o strongly agreed or agreed that total implantarthroplasty should be reserved for those cases

where joint destruction is present on the baseof the proximal phalanx and also the head ofthe first metatarsal.

65% strongly agreed or agreed that structuralrealignment of the first metatarsal with metatar-sal osteotomy is essential in obtaining correc-tion of the deformity.

80% strongly disagreed or disagreed with thestatement that implant failure may be related tothe implant design primarily and not to thesurgical indications or technique.

14. 75% strongly disagreed or disagreed that the in-dications for the hemi implant are the same in-dications as for the total implant.

15. 40% agreed and 25% disagreed that hemi im-plants should not be used when there is mild tomoderate degeneration of the head of the firstmetatarsal. 35% were neutral on this issue.

16. 55% were neutral and25% disagreed that morepostoperative complications are noted with thetotal implant in comparison to the hemiimplant.

17 . 60% were neutral in regard to implant ar-throplasty in that it is more commonly perform-ed in the female patient in comparison to themale patient.

ln addition to the responses above, each physiciansurveyed was given an opportunity to make additionalcomments or recommendations. The following questionswere presented and the more common responses areincluded as results.

Approximately how many total implant arthroplastieshave you performed in the last 5 years?

A range of 2 to 150 total implant arthroplastieswere indicated on the survey. Average numberreported over the last 5 years was 17.

Approximately how many hemi implant arthroplastieshave you performed in the last 5 years?

A range of 2 to 200 hemi implant arthroplastieswere indicated on the survey. The average numberreported over the last 5 years was 38.

Which implant design and manufacturer do you preferfor the total first metatarsophalangeal ioint implant?

90o/o ol the surgeons surveyed preferred the Swansontotal first metatarsophalangeal joint implantproduced by Dow Corning.Only 10% surveyed preferred the LaPorta designproduced by Sutter.

Which implant design and manufacturer do you preferfor the hemi first metatarsophalangeal ioint implant?

95% of the surgeons surveyed preferred the Swansonhemi first metatarsophalangeal ioint implantproduced by Dow Corning.Only 5% of those surveyed preferred the LaPorta

design produced by Sutter.

What percent incidence of complications have you notedfollowing total first metatarsophalangeal iointarthroplasty?

8.

9.

10.

11.

12.

13.

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The surgeons surveyed indicated a percent inci-dence of complications following total first metatarso-phalangeal joint arthroplasty ranging from 1 % to 20%with an average incidence of 8%.

What percent incidence of complications have you notedfollowing hemi f irst metatarsophalangeal jointarthroplasty?

The surgeons surveyed indicated a percent incidenceof complications following hemi first metatarsophal-angeal joint arthroplasty ranging from -l % to 10% withan average incidence oI 4.5%.

What factors do you feel contribute to implantarthroplasty failure?

ln addition to the factors already presentregarding successful implantation of the firstmetatarsophalangealjoint, the following is a summarylist of factors contributing to implant arthroplastyfailure according to the surgeons surveyed.

1. Failure to reduce soft tissue contractures2. Poor surgical technique3. Poor patient selection4. Excessive compression or tension on implant5. Too little or too aggressive bone resection6. Poor patient compliance7. lmproper indications8. Failure to correct osseous deformity9. Poor bone quality

10. Failure to establish early joint motionpostoperatively

11. Improper selection of implant size12. Traumatic handling of implant13. Use of implant to achieve angular correction14. Lack of postoperative physical therapy15. Basic physical limitations of silastic material

as a substitute for normal bone

SUMMARY . CONCLUSION

The preliminary results of this ongoing study confirmthe assumption that the implant functions mainly as ajoint spacer and must not be depended on to accomplishrestoration of motion and correction of the deformity.100% of the physicians surveyed confirmed thisassumption.

First metatarsophalangeal joint implant arthroplasty inmost cases has been very successful in providing painfree motion.

References

1. Heubach F: Ueber hallux valgus and seine operativebehandlung nach edm. Rose Dtsch Ztschr Chir46:210-275, 1897.

2. Keller WL: The surgical treatment of hallux valgussurgery and bunions. N Y Med J 80:741-742,1904.

3. Endler F: Zur entrichlung einer kuenstlichen athro-plastik des grosszehengrundgelenkes und ihrebisherlge indikation. Ztschr Orthop 80:480-387, 1951.

4. Sieffert J: Nylons als knorpelersatz bei der hallux valgusopertion. Dtsch Med J 4:41L145, 1953.

5. Swanson A, Lumsden R, Swanson CD: Silicone implantarthroplasty of the great toe: a review of single stemand flexible hinge implants. C/in Orthop 142:30-43,1979.

6. Vanore JV, O'Keefe R, Pikscher I: First metatar-sophalangeal joint implant arthroplasty. lnMcGlamry ED (ed): Comprehensive Textbook of FootSurgery, vol 1. Baltimore, Williams & Wilkins, 1987,pp 756-807.

7. Vanore .f, O'Keefe R, Pikscher I: Silastic implantarthroplasty: complications and their classification.J Am Podiatry Assoc 74:423-433, 1984.

8. Mondul M, Jacobs PM, Caneva R, Crowhurst J,

Morehead D: lmplant arthroplasty of the firstmetatarsophalangeal joint: a 12-year retrospectivestudy. J Foot Surg 24:275-279, 1985.

9. Weil LS, Pollack RA, Goller WL: Total first metatarsaljoint replacement in hallux valgus and hallux rigidus.Cl i n ics Pod iatry 1 :103-129, 1984.

Additional References

Aenson D.l: The angled great toe implant (Swansondesign/Weil modification) in the surgical reconstruc-tion of the first metatarsophalangeal joint. ClinicsP od i at ry4 :89-1 02, 1984.

AIkin RL, Weil LS: Flexible implant arthroplasty of thegreat toe: an evaluation. J Am Podiatry Assoc64:967-975, 1974.

Dobbs BM: Hemi-implants in foot surgery. Symposiumon implants in foot surgery. Clinics in Podiatry1:79-87, 1984.

Vanore J, O'Keefe R, Pikscher l: Complications of siliconeimplants in foot surgery. Symposium on implants infoot surgery. Clinics in Podiatry 1:175-196,1984.

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