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Breakage of the femoral compo-nent of modern total hip pros-theses is rare. We report the

case of a 65-year-old man who under-went staged bilateral cemented totalhip replacement with titanium pros-theses (Biomet; Warsaw, Ind.). Threeyears later the prosthesis on the rightfailed and was revised. Then, 2 yearsafter that, the contralateral prosthesisalso failed.

CASE REPORT

A physically fit 65-year-old manunderwent bilateral total hip replace-ment (Fig. 1) in 1991. He weighed

more than 90 kg, a factor that mayhave contributed to the stem break-

age.1,2 After informed consent was ob-tained, he was randomized to have ce-

Case ReportÉtude de cas

BILATERAL FEMORAL COMPONENT BREAKAGE IN TOTALHIP REPLACEMENT: A CASE REPORT

Paraic Murray, MSc, MCh; Cecil H. Rorabeck, MD

From the London Health Sciences Centre, University Campus, The University of Western Ontario, London, Ont.

Accepted for publication Jan. 30, 1997

Correspondence to: Dr. Cecil H. Rorabeck, London Health Sciences Centre, University Campus, 339 Windermere Rd., London ON N6A 5A5; tel. 519 663-2910; fax. 519 663-3838; crorabec@julian.uwo.ca

© 1998 Canadian Medical Association (text and abstract/résumé)

Breakage of the femoral component of a total hip replacement prosthesis is an uncommon occurrence withmodern prostheses. The authors report what appears to be the only case of bilateral prosthetic fracture. A65-year-old man, who was physically active, suffered bilateral femoral stem fractures 3 and 5 years after to-tal hip replacement. The bilateral cemented hip replacements remained asymptomatic until catastrophicfailure of the femoral component occurred. Both the prostheses were titanium (Biomet; Warsaw, Ind.)with chrome cobalt modular femoral heads. The authors stress the importance of maintaining an adequatecement mantle in Gruen zones 1 and 7 because failure to do so may result in micromotion and subsequentstem fracture.

Avec les prothèses modernes, il est rare que la pièce fémorale d’une prothèse de remplacement total de lahanche se brise. Les auteurs présentent un compte rendu sur ce qui semble constituer le seul cas de fracturebilatérale d’une prothèse. Un homme âgé de 65 ans qui était actif physiquement a subi des fractures bi-latérale de la tige de la pièce fémorale trois et cinq ans après une arthroplastie totale de la hanche. Les rem-placements cimentés de la hanche sont demeurés asymptômatiques jusqu’à la rupture catastrophique de lapièce fémorale. Les deux prothèses étaient en titane (Biomet; Warsaw, Ind.) et comportaient des têtes fé-morales modulaires au chrome et au colbalt. Les auteurs soulignent qu’il importe de maintenir une couchede ciment suffisante dans les zones 1 et 7 de Gruen. Sinon, il peut se produire des micromouvements quirisquent de provoquer par la suite un bris de la tige.

FIG. 1. Radiograph of the hips of the 65-year-oldman before hip replacement.

FIG. 2. Postoperative radiograph of a right totalhip joint replacement.

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mented total hip replacements as partof an ongoing study comparing ce-mented and cementless total hip re-placement. Prosthesis size was chosento provide a cement mantle3 of at least2 mm over the entire prosthesis afterstandard preparation of the proximalfemur (Fig. 2).Follow-up x-ray films revealed pro-

gressive loosening of the acetabularcomponents bilaterally (Fig. 3), buthe remained asymptomatic and con-tinued to participate in physical activi-ties, which included golf.Close inspection of the radiographs

demonstrated a lucent line developingbetween the prosthesis and the ce-ment bilaterally in Gruen4 zones 1 and7 (Fig. 4). Eventually the prosthesisfractured in its mid-portion, at thelower end of this lucency (Fig. 5). The

prosthesis on the left failed in 1994and that on the right in 1996. Inspec-tion of the latter prosthesis showedthat this breakage occurred close tobut not directly at the junction of thesurface texture change (Fig. 6). Theoriginal prosthetic fracture was in asimilar position. Burnishing was evi-dent both proximal and distal to thestem fracture (Fig. 7). The burnishingwas evident mainly on the medial andposterior surfaces. The extent of theburnishing provided direct evidenceof movement of the prosthesis in thecement mantle along much of thestem length. At the time of revisionthe distal portion of the prosthesis waswell fixed in the cement mantle.

DISCUSSION

The Young’s modulus of titaniumand the relatively small cross-section

of the prosthesis predispose this im-plant to deformation when loaded.Cantilever bending5 presumably pro-duced flow of the cement in the prox-imal femur, particularly in zones 1 and7. The cancellous bone supportingthis cement may not have been sup-portive enough to prevent this coldflow of the cement. There was no evi-dence of failure of the cement mantlebefore fracture of the prosthesis, butsuch failure cannot be ruled out byour x-ray films.Preparation of the femoral shaft for

cemented total hip replacement com-monly involves taper pin reamers andrasps. The reamers open up the proxi-mal diaphysis, usually until the densetransition from cancellous to corticalbone is reached. The rasps prepare thecancellous metaphysis, generally pro-viding a bed for the prosthesis and apredetermined cement mantle. In pa-tients with excellent bone this proxi-mal cancellous bed can support theproximal prosthesis and cement. How-ever, the fractured trabeculae in theproximal femur may either be poroticor heal unpredictably, leading to poorsupport of the implant proximally.6 Ifexcessive trabecular bone is left in zone7, it might not allow a 2-mm mantleto be properly fixed to the transitionaltrabeculae. If this were to occur, mi-

FEMORAL COMPONENT BREAKAGE

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FIG. 3. Progressive loosening of the acetabularcomponents after hip replacement.

FIG. 4. The development of a lucent line in Gruenzones 1 and 7 (arrows).

FIG. 5. The fractured stem of the left prosthesis.

FIG. 6. The fractured prosthetic stem.

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FIG. 7. The fractured prosthetic stem with ap-parent burnishing.

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MURRAY AND RORABECK

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cromovement would be possible andfailure in the form of fracture of thestem might occur, particularly if theimplant was well fixed distally. Ifmovement is allowed to persist, even-tually osteolysis will occur, furthercompounding the micromotion.Eventually osteolysis can undermine apreviously well-fixed implant.Prosthesis fracture at the point

where the distal stem was well fixedand the proximal stem unsupportedwas common with the early Charnleyprostheses.7 Prosthesis modificationand the introduction of Orthron 90(DePuy, Warsaw, Ind.) have elimi-nated this mode of failure for theCharnley prosthesis.In our case the implant used was ti-

tanium. From an early stage a radiolu-cent line was seen between the pros-thesis and the cement in zones 1 and7. This gap on supine x-ray films mayhave been due to bending of the pros-thesis, flow in the cement or tappingof wear debris pumped into the gapduring cyclical loading (Fig. 8). Cycli-cal bending of the prosthesis obvi-ously occurred, as evidenced by theburnishing of the prosthesis on eitherside of the ultimate prosthetic frac-ture. Cyclical bending of a distallyfixed prosthesis, resulted in fatiguefailure as the degree of deflection wasabove the fatigue threshold. Given

that the prosthesis in question was arelatively small cross-section, alongwith the lower Young’s modulus of ti-tanium, the degree of bending ex-pected would be greater than that of abulkier prosthesis made from a stain-less steel alloy.The advantage of titanium in joint

replacement lies in its ability to osseoin-tegrate. Titanium is no longer recom-mended for the bearing surface in jointreplacements, and its role in cementedjoint replacement may also be in ques-tion. Although a cemented titaniumfemoral stem is no longer recom-mended, it is important to point outthe importance of maintaining an ade-quate cement mantle in Gruen zones 1and 7 as failure to do so may result inmicromotion and subsequent stemfracture irrespective of the metal used.

References

1. Charnley J. Fracture of femoral prosthe-sis in total hip replacement. A clinicalstudy. Clin Orthop 1975;111:105-20.

2. Wroblewski BM. Fractured stem in to-tal hip replacement. A clinical review of120 cases. Acta Orthop Scand 1982;

53:279-84.

3. Ebramzadeh E, Sarmiento A, McKil-lop HA, Llinas A, Gogan W. The ce-ment mantle in total hip arthroplasty.Analysis of long term radiographic re-sults. J Bone Joint Surg [Am] 1994;76:77-8.

4. Gruen TA. “Modes of failure” of ce-mented stem-type femoral compo-nents: a radiographic analysis of loos-ening. Clin Orthop 1979;141:17-27.

5. Jones PR, Hukins DW, Porter ML,Davies KE, Hardinge K, Taylor CJ.Bending and fracture of the femoralcomponent in cemented total hip re-placement. J Biomed Eng 1992;14:9-15.

6. Carlsson AS, Gentz CF, Stenport J.Fracture of the femoral prosthesis intotal hip replacement according toCharnley. Acta Orthop Scand 1977;48:650-5.

7. Dall DM, Learmont ID, Solomon MI,Miles AW, Davenport JM. Fracture andloosening of the Charnley femoralstems. Comparison between first- generation and subsequent designs. J Bone Joint Surg [Br] 1993;75:259-65.

FIG. 8. Radiograph showing wear debris.

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Books and Other Media Received

Livres et autres documents reçus

This list is an acknowledgement of books and other me-

dia received. It does not preclude review at a later date.

Cette liste énumère les livres et autres documents reçus.

Elle n’en exclut pas la critique à une date ultérieure.

Atlas of Breast Disease Management. 50Illustrative Cases. A.J. Evans, A.R.M. Wil-son, R.W. Blamey, J.F.R. Robertson, I.O.Ellis and C.W. Elston (The Breast Unit,

Nottingham City Hospital, Nottingham,UK). 146 pp. W.B. Saunders CompanyLtd., London, UK; Harcourt Brace & Co.Canada Ltd., Toronto. 1998. Can$130.ISBN 0-7020-2252-7

Stents in Endovascular Surgery. BasicConcepts and Techniques. Frank J. Criado.124 pp. Illust. Futura Publishing CompanyInc., Armonk, NY. 1996. US$49.

Docket: 1-5527 Initial: JNCustomer: CJS June/98