Revision total knee arthroplasty using the porous-coated anatomic revision prosthesis

The Journal of Arthroplasty Vol. 13 No. 6 1998

Revision Total Knee Arthroplasty Using the Porous-Coated Anatomic Revision Prosthesis Six- to Twelve-Year Results Christopher

S. M o w ,

MD,*J- and Jerome

D. W i e d e l , M D *

Abstract: The p o r o u s - c o a t e d a n a t o m i c (PCA) r e v i s i o n p r o s t h e s i s was o n e of t h e earliest r e v i s i o n total k n e e s y s t e m s to f e a t u r e m o r e c o n s t r a i n t for stability, s t e m s for fixation, a n d t h i c k e r f e m o r a l c o m p o n e n t s to address b o n e loss. F r o m 1981 to 1989, 36 r e v i s i o n total k n e e a r t h r o p l a s t i e s w e r e p e r f o r m e d u s i n g t h e PCA prosthesis. P a t i e n t s

were evaluated by clinical examination, radiographs, and the Hospital for Special Surgery Knee Rating Scale. Six patients died and three were lost to follow-up; 27 knees remained for follow-up. The average age at surgery was 66 years. Follow-up averaged 9.8 years (range, 6-12.4 years). Range of motion averaged 4 ° to 91 ° before surgery and 1° to 92 ° after surgery. Knee scores averaged 48 before surgery and 86 after surgery. Three femoral and 10 tibial components showed lucent lines, with 3 tibial components showing progressive lucency. Six patients required reoperation: 3 for tibial component loosening, 1 for wound infection, 1 for deep infection, and 1 for persistent pain. These results suggest that the use of an implant specifically designed for revision can yield successful long-term results. Key words: revision, knee, arthroplasty, prosthesis, long-term results.

Revision total knee arthroplasty presents the reconstructive surgeon with particular challenges, including exposure, instability, ligamentous loss or i n c o m petence, b o n e loss, poor bone quality, and fixation. M a n y revision prosthesis systems have been introduced over the years to provide stability, a u g m e n t a tions for b o n e loss, a n d stems for fixation. Introduced in 1981, the porous-coated anatomic (PCA) revision prosthesis was one of the earliest of these systems to feature more constraint of the tibiofemoral articulation for stability, stems of varying lengths for additional fixation, and thicker femoral c o m p o -

nents to address bone loss (Fig. 1). Unlike the c o n t e m p o r a r y counterparts, the original PCA revision knee system was n o t modular, and all components were one piece. In the original PCA revision knee system, both femoral and tibial c o m p o n e n t s were made of vitallium alloy and porous-coated. Femoral c o m p o n e n t s were constructed for right and left and available in three sizes: small, 63 m m wide mediolaterally and 55 m m anteroposteriorly; medium, 70 m m wide mediolaterally and 60 m m anteroposteriorly; large, 74 m m wide mediolaterally and 66 m m anteroposteriorly. Small femoral c o m p o n e n t s were available in two thicknesses and stem lengths, 12.5 m m thick with an 8 6 - r a m stem a n d 17.0 m m thick with a 1 l O - m m stem. M e d i u m femoral c o m p o n e n t s were available in three thicknesses and stem lengths, 11 m m or 15 m m thick with an 8 6 - m m stem, and 20 m m thick with a i 2 0 - m m stem. Large femoral c o m p o n e n t s were available in three thicknesses and stem lengths, 11 m m or 15 m m thick with an

From the *Department of Orthopaedics, University of Colorado Health Sciences Center, Denver, Colorado; and the pStanford University Medical Center, Stanford, Cahfornia. Presented in part at the Annual Meeting of the Western Orthopaedic Association, Kauai, HI, August 1996. Reprint requests: Christopher S. Mow, MD, 2970 Hilltop Mall Road, Richmond, CA 94806. Copyright © 1998 by Churchill Livingstone® 0883- 540311306-0013 $ 3.00/0

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a n d failure in the long term, given the high stresses t h a t are t r a n s m i t t e d to the p r o s t h e s i s - b o n e or b o n e c e m e n t interfaces, c o m p a r e d to p r i m a r y type implants [ I 6 , I 7 , 1 9 , 2 4 ] . Given the paucity of longt e r m results of revision total k n e e arthroplasty using a revision type prosthesis system in the literature, w e r e v i e w e d the experience at the University of Colorado using the PCA revision total k n e e prosthesis system.

Materials and Methods

Fig. I. The porous-coated anatomic revision prosthesis.

8 6 - r a m stem, and 20 m m thick with a 130-111111 stem. All femoral stems w e r e smooth, mildly tapered, circular in cross section, a n d 11 m m in diameter. Tibial c o m p o n e n t s w e r e available in three sizes: small, 67 m m wide mediolaterally and 40 m m anteroposteriorly; m e d i u m , 72 m m wide mediolaterally and 46 m m anteroposteriofly; large, 77 m m wide mediolaterally a n d 50 m m anteroposteriorly. All tibial compon-efits w e r e available w i t h a standard p r i m a r y s t e m length of 52 m m , a long stem of 100 m m , or exceptionally long ("extra-long") s t e m of 130 m m . The tibial stems w e r e smooth, tapered, h a d a square cross section, a n d w e r e i0 m m wide. The tibial polyethylene inserts w e r e n o n m o d u l a r (prefabricated attached to the baseplate), a n d w e r e available in 3 - m m increments, f r o m i0 to 25 ram. Elevated anteroposterior (AP) tibial plateau margins provided m o r e c o n f o r m i t y to the f e m o r a l condyles in order to give the articulation m o r e constraint t h a n the p r i m a r y type PCA insert. Although there are m a n y reports in the literature on revision total k n e e arthroplasty [1-27], few are followed-up longer t h a n 5 to 6 years [4-6,13,18], and e v e n f e w e r are based solely on the results of one prosthesis type [17,19,24]. A m a j o r concern to the total joint reconstructive surgeon a b o u t the use of bulkier, highly constrained revision type implants is w h e t h e r these implants will be p r o n e to loosening

F r o m 1981 to 1988, 36 revision total k n e e arthroplasties w e r e p e r f o r m e d in 34 patients using the PCA revision prosthesis: 31 w e r e tibial a n d f e m o r a l revisions a n d 5 w e r e tibial revisions. There w e r e 14 m e n a n d 20 w o m e n . The average age at surgery was 66 years (range, 2 6 - 7 8 years). The original diagnosis indicating p r i m a r y total k n e e a r t h r o p l a s t y was osteoarthritis in 23 knees, r h e u m a t o i d arthritis in 11 knees, a n d hemophilic a r t h r o p a t h y in 2 knees. The n u m b e r s of revisions p e r f o r m e d w e r e 15 for tibial loosening, 11 for tibial a n d femoral loosening, 5 second-stage reimplantations for infection, 4 for f e m o r a l loosening, a n d 1 for instability; 30 knees w e r e revised for the first time, 4 for the second time, a n d 2 for the third time or m o r e . The average interval b e t w e e n the previous arthroplasty a n d the i n d e x revision was 5.7 years (range, 4 m o n t h s to 15 years). Prostheses r e m o v e d in revision w e r e i0 PCA, 8 UCI, 3 Spherocentric, 2 Guepar, 2 Geomedic, 1 M a r m o t , i N e w Jersey/Depuy, 1 3M Multicentric, 1 Townley, 1 Custom, and 2 u n k n o w n types. In revision, 9 f e m o r a l and 10 tibial c o m p o n e n t s w e r e i m p l a n t e d w i t h o u t cement. W h e n used, c e m e n t was applied to the undersurface of the femora÷ c o m p o n e n t , tibial baseplate, a n d cut b o n e surfaces. C e m e n t was not intentionally applied to the stems n o r injected into the femoral or tibial canals; 22 f e m o r a l c o m p o n e n t s h a d no stem, 6 h a d 8 6 - m m stems, a n d 3 h a d 1 5 0 - m m stems; 25 tibial c o m p o n e n t s h a d p r i m a r y length ( 5 2 - m m ) stems, 8 h a d long ( i 0 0 - m m ) stems, a n d 3 h a d extra-long (130m m ) stems. Major structural allografts w e r e used for large, u n c o n t a i n e d defects in 6 p r o x i m a l tibias a n d 4 distal femurs, the techniques a n d results of w h i c h h a v e b e e n previously described by us [12]. Iliac crest b o n e graft was used for the smaller c o n t a i n e d type of defects in i 0 p r o x i m a l tibias and 10 distal femurs. Major additional procedures included 6 extensive lateral releases, 5 medial collateral ligament advancements, 5 lateral collateral ligament a d v a n c e m e n t s , 4 tibial tubercle osteotomies for exposure, 1 patellec-

PCA Revision Total KneeArthroplasty

tomy, 1 quadriceps V-Y-plasty, and 1 semitendinosus patellar t e n d o n augmentation. Six patients died and 3 were lost to follow-up, leaving 27 knees for follow-up, w h i c h averaged 9.8 years (range, 6.5-12.4 years). Patients were evaluated by clinical examination, radiographs, a n d the Hospital for Special Surgery (HSS) Knee Rating Scale. Pain was assessed as mild, moderate, or severe. Instability in the mediolateral direction was assessed clinically, as described by Insall in the HSS Knee Rating Scale, with 5 ° to 10 ° of instability considered as mild, l 0 ° to 15 ° as moderate, and greater t h a n 15 ° as severe [28-30]. Radiographs were taken in standing AP, lateral, and skyline patellar views, and reviewed for lucent lines, c o m p o nent migration or loosening, b o n e changes (such as osteolysis a n d cortical hypertrophy), and evidence polyethylene wear (defined as a s y m m e t r y b e t w e e n medial and lateral tibial polyethylene thickness of greater t h a n 2 m m in a standing AP view radiograph). Radiolucent lines were measured in millimeters and localized according to the zones described by Ewald [3] in the criteria of the Knee Society, with 7 femoral zones in the lateral view, 7 tibial zones in the AP view, 3 tibial zones in the lateral view, and 3 patellar zones in the skyline view. C o m p o n e n t s were considered loosened if b o n e c e m e n t radiolucent lines were circumferential and greater t h a n 2 m m or progressive, or if c o m p o n e n t migration or breakage occurred.

Results Range of m o t i o n averaged 4 ° to 9i ° before surgery (range, 00-25 ° extension to 4 5 ° - 1 2 0 ° flexion), and 1° to 92 ° after surgery (range, 0o-5 ° extension to 70°-125 ° flexion). The average HSS knee score was 48 points before surgery (range, 2 0 - 6 0 points) and 86 points after surgery (range, 77-92). Alignm e n t before surgery averaged 3 ° of varus (range, 25 ° valgus to 20 ° varus). Before surgery, only 9 knees were b e t w e e n 0 ° and l0 ° of valgus. After surgery, alignment averaged 5 ° valgus (range, 3 ° varus to 8 ° valgus). All patients h a d m o d e r a t e to severe pain before surgery. After surgery, 1 patient h a d m o d e r a t e pain (including at rest; see below), 4 had mild pain, and the remainder were pain-free. Before surgery 9 knees had s e v e r e m e d i a l lateral instability, 22 h a d moderate instability, 4 h a d mild instability, a n d i was stable. After surgery 1 knee had m o d e r a t e instability, 12 h a d mild instability, and the remaining were stable. Two femoral c o m p o n e n t s h a d a nonprogressive lucent line of less t h a n l m m u n d e r the anterior flange in zones 1 and 2, and one c o m p o n e n t h a d a

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nonprogressive lucent line of less than 1 m m u n d e r the posterior r u n n e r s in zones 3 and 4. Five tibial c o m p o n e n t s s h o w e d nonprogressive lucent lines of less t h a n 1 m m in AP view zones 1 and 4 only. Two tibial c o m p o n e n t s s h o w e d nonprogressive lucent lines in both AP view zones 1 and 4 and lateral view zones 1 and 2. In one of these, the lucent lines were less t h a n i ram, and in the other t h e y were b e t w e e n 1 to 2 ram. Two tibial c o m p o n e n t s had nonprogressive lucent lines of less t h a n i m m in only one zone, one of w h i c h was in AP view zone 1 and the other in AP view zone 4. Two tibial c o m p o n e n t s s h o w e d circumferential progressive lucent lines of i to 2 m m in all AP view and lateral view zones, and were considered loose. Both were confirmed to be loose at the time of revision (see below). One tibial comp o n e n t s h o w e d progressive lucent lines of 2 m m in AP view zones 1 and 4, and 1 m m in lateral view zone l, and migrated and fractured (see below). Evidence of p o l y e t h y l e n e w e a r was n o t e d medially in 2 knees, but no clear osteolytic lesions were seen. Cortical h y p e r t r o p h y was seen adjacent to the tips of 1 femoral and 1 tibial stem, neither of w h i c h correlated with a n y symptoms. Sclerotic lines adjacent to stems were seen with 3 femoral and 2 tibial components, n o n e of w h i c h correlated with any symptoms (Fig. 2A,B). All structural allografts united at the graft host junction, as evidenced by overlapping callus or cross trabeculation. There were n o fractures, infections, or c o m p o n e n t loosenings associated with use of allografts.

Complications Six patients required reoperation, 3 for tibial c o m p o n e n t loosening, 1 for w o u n d infection, l for deep infection, and 1 for persistent pain. One patient with tibial loosening was a 58-year-old m a n w h o u n d e r w e n t a revision for a loosened Spherocentric prosthesis. At 4 years after surgery, he developed severe posterior instability and tibial loosening. He was offered re-revision or knee fusion as salvage procedures, and he chose the latter. He is currently functioning well with a successful fusion. The second patient with tibial loosening was a 61-year-old w o m a n w h o h a d a loosened UCI prosthesis. At 7 years after surgery, she developed loosening of the tibial c o m p o n e n t , w h i c h was revised using a segmental structural allograft for the proximal tibial bone loss with a l o n g - s t e m m e d c o m p o n e n t . She is currently functioning well with a knee score of 87. The third patient with tibial loosening was a 75-year-old m a n w h o was initially revised for a loosened PCA tibial c o m p o n e n t . After functioning well for 7 years, he developed progressive varus deformity a n d pain, and was f o u n d to

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C Fig. 2. (A) A 58-year-old man with rheumatoid arthritis, 7-year status after original UCI-type total knee arthroplasty, showing gross loosening. (B,C) Anteroposterior and lateral views 12 years after revision using stemmed porous-coated anatomic revision femoral and tibial components. There is no evidence of loosening, wear, or osteolysis. His knee score was 87.

have a fractured medial baseplate (Fig. 3). He u n d e r w e n t revision with a c e m e n t e d c o m p o n e n t and is currently functioning well. A w o u n d infection developed in one patient 1 m o n t h after surgery. She was successfully treated with irrigation and debridement and intravenous antibiotics, and died 4 years later from unrelated causes. A deep infection developed in one patient with hemophilic a r t h r o p a t h y 3 years after surgery, which was treated with prosthesis removal and knee fusion. One patient complained of persistent pain, including at rest, despite good radiographic appearance of her prosthesis. She was reexamined, and at the time of surgery, her c o m p o n e n t s were f o u n d to be well fixed and aligned. After surgery, her pain continued, and she is currently m a n a g e d with pain control methods.

Discussion Although there are m a n y reports in the literature on revision total k n e e arthroplasty, few are on the use of one specific revision prosthesis system. Jacobs et al. [ l I ] reported on 28 revision total knee arthroplasties using both the PCA primary and revision components, with an average 2 9 - m o n t h follow-up. Overall, 68% of patients had a good or excellent result, and the investigators concluded

that those patients w h o had definable mechanical problems with their failed arthroplasty had the best results. Rosenberg et al. [ 191 reported o n 39 revision total k n e e arthroplasties using the Total Condylar III, a constrained type of prosthesis. At the average 4 5 - m o n t h follow-up, 69% were rated as good to excellent. They concluded that the Total Condylar III prosthesis was effective for salvaging unstable failed total knee arthroplasties, but because of a 60% lucent line rate, they also r e c o m m e n d e d that less-constrained devices be used w h e n e v e r possible. Rand and Bryan [16] reported o n 50 revisions using condylar-type prostheses with an average follow-up of 4.8 years. This operation p r o d u c e d a good or excellent result in 76% of patients, and lucent lines were seen in 17% of patients. They r e c o m m e n d e d that if the collateral ligaments were absent, a more constrained type of implant should be used. Rand [17] also reported on his experience using the Total Condylar III prosthesis in 21 patients with an average 4-year follow-up. Half the patients had a good or excellent result, and 33% experienced significant complications. He concluded that the results of revision total knee arthroplasty using the Total Condylar III were similar to those of other constrained-type implants. Vince and Long [24] recently reported o n 44 revisions using a modular s t e m m e d implant, w h e r e

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Fig. 3. (A) A 75-year-old man's 5-year status after tibial revision with a noncemented porous-coated anatomic revision component. The original porous-coated anatomic tibial component had failed in varus in 1 year, and at the time of revision, bone grafting to the medial tibia was required. The patient functioned well with no pain for 7 years. Note the lucent line in tibial zone 4. (B) At 7 years after surgery, progressive varus deformity developed with pain over a 4-month period. The tibial component was found to be loosened and fractured. He underwent a second revision using a cemented tibial component and allograft bone to reconstruct the medial tibial bone loss. (Reprinted with permission [ 15].)

the implant was c e m e n t e d to the cut bone surface and the stem was press-fit into the medullary canal. Constrained-type articulations were used in 10 patients, and 2 of these h a d loosened by 3 years. The researchers concluded that press-fit stem fixation w i t h o u t c e m e n t m a y not be sufficient fixation for the constrained-type devices. Haas et al. [7] recently reported on 76 revisions using m o d u l a r c o m p o n e n t s with stems inserted w i t h o u t c e m e n t with an average follow-up of 3]/2 years; 19 of the revisions h a d constrained-type components. The average HS S knee score at latest follow-up was 76 points, and 84% had a good or excellent result. In contrast to the findings of Vince and Long [24], they did n o t find any increase in loosening rates b e t w e e n the constrained implants w h e n compared to the n o n c o n strained-type implants. Just as there are few reports on revision total knee arthroplasty using one prosthesis system, there are also few that have follow-up longer t h a n 5 to 6 years [4-6,13,18]. We previously reported on a series of 17 n o n c e m e n t e d revision total knee arthroplasties, 13 of w h i c h were with the PCA revision knee prosthesis, with an average 5.6-year followup [13]. Twelve patients were assessed as good or excellent, and we concluded that successful revision total knee replacement was possible using n o n c e m e n t e d p o r o u s coated fixation in appropriate situa-

tions. Gustilo et al. [6] recently reported on 56 revisions using various prosthesis types with an average follow-up of 8.3 years; 73% rated good or excellent, and no difference in o u t c o m e was n o t e d b e t w e e n prosthesis types used. C o m p o n e n t alignm e n t was identified as being the most important factor in determining success. The current series has the longest term reported m e a n follow-up using one prosthesis type in the literature to o u r knowledge. A good or excellent result (HSS knee score of 80 or above) was produced in 58% of patients. Lucent lines were seen in 36% of cases, and definite loosening of the tibial compon e n t was seen in 8%. The deep infection rate was 2.7%. These results and complication rates are comparable to other reports in the literature that have shorter-term follow-up. The reported success rate of revision total knee arthroplasty has been highly variable, ranging f r o m ' 2 3 % to 89% [1-27]. Meaningful comparison b e t w e e n series is difficult given the multitude of prosthesis types and different surgical techniques used. Most c o n t e m p o r a r y prosthesis designs have m o d u l a r stem, augment, and constraint options for revision surgery. Of these, the PCA revision prosthesis was one of the earliest to have these features. These results suggest that the use of an implant specifically designed for revision use can yield successful l o n g - t e r m results, and the

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increased bulk and constraint of this particular revision implant has not resulted in increased rates of loosening and failure w h e n compared to other series in the literature.

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15. Rand JA, Peterson LFA, Bryan RS, Ilstrup DM: Revision total knee arthroplasty. AAOS Instruct Course Lect 35:305, 1986 16. Rand JA, Bryan RS: Results of revision total knee arthroplasty using condylar prostheses: a review of 50 cases. J Bone Joint Surg [Aml 70:738, 1988 17. Rand JA: Revision total knee arthroplasty using the total condylar III prosthesis. J Arthroplasty 6:279, 1991 18. Rooser B, Boegard T, ICnutson K, Rydholm U, Lidgren L: Revision total knee arthroplasty in rheumatoid arthritis. Clin Orthop 219:169, 1987 19. Rosenberg AG, Verner J J, Galante JO: Clinical results of total knee revision using the total condylar III prosthesis. Clin Orthop 273:83, 1991 20. Samuelson ICM: Bone grafting and n o n c e m e n t e d revision arthroplasty of the knee. Clin Orthop 226:93, 1988 21. Scott RD: Revision total knee arthroplasty. Clin Orthop 226:65, 1988 22. Thornhill TS, Dalziel RW, Sledge CB: Alternatives to arthrodesis for the failed total knee arthroplasty. Clin Orthop 170:131, 1982 23. Vince KG: Revision knee arthroplasty technique. AAOS Instruct Course Lect 42:325, 1993 24. Vince KG, Long W: Press fit long stem revision total knee arthroplasty. Presented at the A n n u a l Meeting of the Knee Society, New Orleans, LA, Feb. 1994 25. Whiteside LA: Cementless reconstruction of massive tibial bone loss in revision total knee arthroplasty. Clin Orthop 248:80, 1989 26. Whiteside LA: Cementless revision total knee arthroplasty. Clin Orthop 286:160, 1993 27. Wiedel JD, Jonassen EA: Revision of failed total knee arthroplasties: a review of twenty knees. Orthop Trans 12:157, 1988 28. Insall JN, Ranawat CS, Aglietti E Shine J: A comparison of four models of total knee replacement prostheses. J Bone Joint Surg [Am] 58:754, 1976 29. Insall JN: Total knee replacement, p 587. In Insall JN (ed): Surgery of the knee. Churchill Livingstone, New York, 1984 30. Ranawat CS, Insall JN, Shine J: Duo-condylar knee arthroplasty: hospital for special surgery design. Clin Orthop 120:76, 1976