Prevalence of Osteolysis After Simultaneous Bilateral Fixed- and Mobile-Bearing Total Knee Arthroplasties in Young Patients

The Journal of Arthroplasty Vol. 24 No. 6 2009

Prevalence of Osteolysis After Simultaneous BilateralFixed- and Mobile-Bearing Total Knee Arthroplasties

in Young Patients

Young-Hoo Kim, MD, and Jun-Shik Kim, MD

Abstract: This study aimed to evaluate the clinical and radiographic results and todocument the prevalence of osteolysis associated with fixed-bearing (anatomicmodular knee) and mobile-bearing (low contact stress) total knee arthroplasties(TKAs) in 61 patients younger than 55 years who had bilateral simultaneous primaryTKAs. Forty-five patients were female and 16 patients were male. The mean age ofthe patients was 48.3 years (range, 34-55 years). The mean postoperative KneeSociety knee and functional score were similar in both groups (91 and 90 points and85 and 86 points, respectively). Three knees (5%) in each group were revised forwear of the tibial bearing, and 1 knee (2%) in the mobile-bearing TKA was revisedfor dislocation of the meniscal bearing. Osteolysis was identified in both radiographsand computed tomography scans in 6 knees (10%) in the anatomic-modular-kneegroup and 4 knees (7%) in the low-contact-stress group. Keywords: osteolysis,fixed-bearing, mobile-bearing, total knee arthroplasty, young patients.© 2009 Elsevier Inc. All rights reserved.

Total knee arthroplasties (TKAs) with well-designed, fixed-bearing prostheses have provideddurable long-term fixation with prosthetic survivalrates of 95% to 97% reported at 10 to 15 years [1-9].However, polyethylene wear and periprostheticosteolysis have been problems in fixed-bearingTKA [10-13].A mobile-bearing TKA was introduced to mini-

mize interface stresses between the implant andbone. One commonly stated reason for using a

From the The Joint Replacement Center of Korea, Ewha Woman'sUniversity School of Medicine, Seoul, South Korea.

Submitted August 8, 2007; accepted May 2, 2008.Read in part at the 74th Annual Meeting of the American

Academy of Orthopaedic Surgeons in San Diego, California,February 14-18, 2007.

No benefits or funds were received in support of the study.Reprint requests: Young-Hoo Kim, MD, The Joint Replace-

ment Center of Korea at Ewha Woman's University, MokDong,Hospital, 911-1, MokDong, YangCheon-Gu, Seoul, 150-710,South Korea.

© 2009 Elsevier Inc. All rights reserved.0883-5403/08/2406-0016$36.00/0doi:10.1016/j.arth.2008.05.005

932

mobile-bearing TKA was that it allows youngerpatients to be more active and to reduce articularand backside wear of the tibial polyethylene bearing[13]. Despite the theoretical advantages of mobile-bearing TKA, the concept that a mobile-bearing TKAis associated with less polyethylene wear and lowerrate of osteolysis than a well-designed fixed-bearingTKA has not been proven in young patients [14-16].

We hypothesized that the mobile-bearing TKAwould improve the clinical and radiographic results,patient satisfaction, and patient activity level inyoung patients (b55 years of age) who underwentbilateral simultaneous TKAs in the same patients.We also hypothesized that mobile-bearing TKAswould result in lower prevalence of osteolysis thanfixed-bearing TKAs.

Materials and Methods

Bilateral simultaneous primary TKAs were per-formed between January 1995 and December 1996by a senior author in 69 consecutive patients who

http://dx.doi.org/10.1016/j.arth.2008.05.005

Simultaneous Bilateral Fixed- and Mobile-Bearing TKAs in Young Patients � Kim and Kim 933

were younger than 55 years during the sameanesthetic session, with one side treated immedi-ately after the other. Five patients were lost tofollow-up before 2 years after the surgery and 3patients were deceased before 5 years after thesurgery. Therefore, 61 patients (122 knees) were leftfor follow-up evaluation. The study was approvedby our institutional review board, and all patientsprovided informed consent. Randomization be-tween the use of an anatomic modular knee(AMK) fixed-bearing prosthesis or low contact stress(LCS) mobile meniscal-bearing prosthesis wasdetermined from a sequential pool based on atable of randomized numbers. Each of the 61patients received an AMK fixed-bearing TKAcomponent on one side and an LCS mobilemeniscal-bearing TKA component on the contral-ateral side. Forty-five patients (90 knees) werewomen, and 16 patients (32 knees) were men.The mean age of the patients at the time of theoperation was 48.3 years (range, 34-55 years). Thediagnosis was osteoarthritis in 58 patients (116knees) and rheumatoid arthritis in 3 patients(6 knees). Twenty patients (31 knees) had anarthroscopic debridement previously. The meanheight of the patients was 152.3 cm (range, 141-185 cm), and the mean weight was 61.9 kg (range,48-106 kg).An AMK TKA (DePuy, Warsaw, Ind) was used

for a fixed-bearing knee arthroplasty, and an LCSmeniscal-bearing prosthesis (DePuy) was used fora mobile-bearing TKA. All implants were of aposterior cruciate–retaining design, and all werefixed with cement. All patellae were resurfacedand were fixed with cement. In the AMK group,all polyethylene patellar prosthesis was used and ametal-backed rotating-bearing patellar prosthesiswas used in the LCS group. All femoral compo-nents in both AMK and LCS groups had apolished cobalt-chromium articular surface (aver-age roughness, b0.1 μm). Also, cobalt-chromiumtibial baseplate in both AMK and LCS groups hada polished proximal surface finish (average rough-ness, b0.1 μm).The initial minimum thickness of the polyethylene

insert averaged 12 ± 2 mm in both groups. The typeof resin of the polyethylene insert was 4150 resin inboth groups, and all were machined to their finalshape from a ram-extruded bar in both groups. Allpolyethylene inserts were sterilized with γ radiationin vacuum in both groups. Information about theresin type and sterilization method of the tibialpolyethylene insert was obtained from the manu-facturers. The mean shelf age of the insert (ie, thenumber of years that had elapsed between steriliza-

tion and implantation) was 0.6 ± 1.1 years in theAMK group and 0.5 ± 1.0 year in the LCS group.

A midline skin incision (10-12 cm in length) wasmade, and a subvastus capsular incision was used inthe joint in all patients. The skin incision was madeas short as possible, but there were no differences indissection based on altered technique between the2 implants in all knees. The intact or degeneratedanterior cruciate ligament was excised, and theposterior cruciate ligament was retained in allpatients. Recession of posterior cruciate ligamentwas required in 8 patients (13%) in the AMKgroup. Recession of posterior cruciate ligament wasnot required in any knee in the LCS group. Inboth groups, femoral preparation was done firstfollowed by tibial preparation. Ligamentous balan-cing was done, and an attempt was made to resect10 mm of tibial bone to achieve a surface that wasperpendicular to the shaft of the tibial in thecoronal plane with 7° posterior slope in the sagittalplane. Distal and posterior femoral condylar resec-tion was done with an attempt to remove athickness of bone that was equal to that of thefemoral component to be implanted. While per-forming the femoral and tibial resection, care wastaken to balance the flexion and extension gapsand alleviate any flexion contracture.

A splint was applied with the knee in 15° flexionand was worn for the first 24 hours after theoperation. The knee then was placed in a continuouspassive motion machine, and the settings on themachinewere advanced incrementally until the kneereached 120° flexion. All patients beganwalking withcrutches or awalker and beganworking on active andpassive range of motion exercise on the second dayafter the operation. The patients used crutches or awalker with full weight bearing for 6 weeks and useda cane if they needed it since then.

Clinical and radiographic evaluations were doneat 6 weeks, 3 months, 6 months, 1 year after theoperation, and yearly thereafter. All clinical datafrom the follow-up examinations were recordedand compiled by 2 observers who were not partof the operative team and who had no knowledgeof the radiographic findings. The mean duration offollow-up was 10.8 years (range, 10-12 years).Preoperative and postoperative ratings according tothe system of the Knee Society [17] and TheHospital for Special Surgery [18] were obtainedfor all patients. The level of activity was assessedfurther with the activity score of Tegner andLysholm [19]. The patients were given a scoreaccording to the activities in which they hadengaged immediately preoperatively and those inwhich they engaged at the time of the latest follow-

934 The Journal of Arthroplasty Vol. 24 No. 6 September 2009

up examination. The score ranges from 0 points fora knee-related disability to 10 points for participa-tion in competitive sports at a national level.Survivorship analysis was performed to deter-

mine the cumulative rate of survival of the implantduring the period of the study [3,20]. Survivorshipoutcomes were reported with 95% confidenceintervals. Significance was considered to be a Pvalue of .05 or less. The end point for analysis wasrevision surgery for any reason or a recommenda-tion for revision surgery by the senior author.Radiographs (anteroposterior view with the

patient standing and supine; lateral and skylineviews) were obtained before and after surgeryunder control of fluoroscopic x-ray examination.The radiographs were assessed for alignment of thelimb, the position of the component, and thepresence and location of all radiolucent lines at

Table 1. Clinical Results in th

Parameters

Knee Society Score

Preoperative Final F

AMK LCS AMK

Total Knee Score (points) 26 26 91Functional score (points) 32 30 85Pain score (points) 0 0 45None – – 37 (61%)Mild – – 22 (36%)Moderate – – 1 (2%)Severe 61 (100%) 61 (100%) 1 (2%)Walking distanceCannot walk 1 (2%) 1 (2%b1 block 16 (26%) 9 (11-5 blocks 36 (59%) 2 (5-10 blocks 5 (8%) 49 (80%Unlimited 3 (5%)Range of motion (degrees) −10° to 128°

(118°)−9° to 127°

(118°)0° to 120°(120°)

Walking supportNo support 45 (74%) 54 (1 cane 13 (21%) 6 (11 crutch –2 crutches 3 (5%) 1 (StairsNormal 1 (2%) 34 (With support 60 (98%) 27 (

Statistics

Knee score (Knee Society Score)Preoperative knee scoreFinal follow-up knee scoreKnee score (Hospital for SpecialSurgery Knee Score)Preoperative knee scoreFinal follow-up knee scorePain score (postoperative)(Mantel-Haenszel trend test)

Range of motion (Student t test)PreoperativeFinal follow-up

the bone-cement interface, according to the recom-mendation of the Knee Society [17].

Preoperatively and postoperatively, the joint lineswere measured in anteroposterior radiographs bymeasuring the distance between the tip of the fibularhead and distal margin of the lateral femoralcondyle preoperatively and between the tip of thefibular head and distal margin of the lateralcomponent postoperatively. The skyline patellarradiographs were examined for patellar tilt, sub-luxation, or dislocation.

For the most recent follow-up, postoperativecomputed tomography (CT) scans using a multi-slice scanner (General Electric Light Plus, Wauke-sha, Wis) were performed to determine theosteolysis in all knees. A scan sequence wasperformed from the 10 cm above the superiorpole of the patella to the 10 cm below the tibial

e AMK and LCS Groups

Hospital for Special Surgery Knee Score

ollow-Up Preoperative Final Follow-Up

LCS AMK LCS AMK LCS

90 47 47 89 8786 – – – –44 6 6 24 23

34 (56%) – – 37 (61%) 34 (56%)24 (39%) – – 22 (36%) 24 (39%)1 (2%) – – 1 (2%) 1 (2%)2 (3%) 61 (100%) 61 (100%) 1 (2%) 2 (3%)

)/3 (5%) 1 (2%) 1 (2%)/3 (5%)5%) 16 (26%) 9 (15%)3%) 36 (59%) 2 (3%))/47(77%) 5 (8%) 49 (80%)/47(77%)

3 (5%)0° to 118°(118°)

−10° to 128°(118°)

−9° to 127°(118°)

0° to 120°(120°)

0° to 118°(118°)

89%) 45 (74%) 54 (89%)0%) 13 (21%) 6 (10%)– – –2%) 3 (5%) 1 (2%)

56%) 1 (2%) 34 (56%)44%) 60 (98%) 27 (440%)

Student t test0.9220.524

0.8490.4220.492

0.9720.650

Table 2. Radiographic Results in the AMK and LCS Group

Parameters AMK LCS t Test

AlignmentPreoperative (degree)Varus1-10 34 knees (56%) 44 knees (72%) 0.13511-20 27 knees (44%) 17 knees (28%) 0.128

Postoperative (degree)Valgus 4.8° (0° to 9°) 5.1° (−2° to 7°) 0.983

Femoral component position (femoral angle)Anteroposterior 95° (96° to 100°) 95° (89° to 99°) 0.936Sagittal 6° (−2° to 17°) 11° (−1° to 21°) 0.089Tibial component position (tibial angle)Anteroposterior 87° (82° to 95°) 88° (82° to 95°) 0.075Sagittal 87° (80° to 95°) 84° (76° to 90°) 0.098Patella component angle 1° (−15° to 20°) 3° (−10° to 31°) 0.11Tibial surface capping 96% (88% to 103%) 95% (87% to 104%) 0.720Joint line (mm)Preoperative 17 (5 to 24) 17 (11 to 25) 0.381Postoperative 14 (9 to 25) 14 (7 to 23) 0.538Posterior condylar offsetPreoperative 27 (20 to 32) 27 (22 to 36) 0.655Postoperative 27 (19 to 36) 26 (18 to 36) 0.519Radiolucent lineAbsence 56 knees (92%) 57 knees (93%) 0.272Presence 5 knees (8%) 4 knees (7%) 0.134


tuberosity, using 2.5-mm contiguous slices. Metal-lic interference (noise) was reduced as much aspossible with a metallic interference removalsoftware program.Osteolysis was defined as any nonlinear region of

periprosthetic cancellous bone loss with delineable

Fig. 1. Radiographs of the left knee of a 49-year-old man with osknee obtained 11 years after surgery reveals that osteolysis isfemoral component. (B) A lateral view of the left knee obtaineentire femoral condyles around the AMK femoral component.

margins. One observer examined all of the radio-graphs and CT scans for osteolysis, and all of theradiographs for radiolucencies at the bone-cementinterface and component migration.

The Fisher exact test was used to compare theprevalence of polyethylene wear and osteolysis.

teoarthritis. (A) A standing anteroposterior view of the leftdemonstrated in the femoral condyles around the AMKd 11 years after surgery reveals extensive osteolysis in the


Probability values of .05 or less (P ≤ .05) wereconsidered to indicate significance. Cox propor-tional hazards regression analysis (SPSS, Chicago,Ill) was used to identify factors that influenced therisk of a knee having osteolysis at 10 to 12 years.A Wilcoxon rank-sum test was performed forcomparisons of nonparametric ordinal data. The κstatistic was used to assess interrater reliability forthe determination of osteolysis.

Fig. 2. Radiographs of a 45-year-old woman with osteoarthritis10 years and 8months after surgery shows metal-on-metal betwthe medial tibial bearing polyethylene. (B) An anteroposteriorsurgery shows the satisfactory position of LCS rotating platformbearing polyethylene shows complete wear and fragmentation

Results

The preoperative and postoperative knee andfunctional scores in both groups were not signifi-cantly different (P N .05) according to the KneeSociety and Hospital for Special Surgery knee scores.Preoperative and postoperative pain score and rangeof motion in both groups were not significantlydifferent (P N .05) (Table 1). The preoperative and

. (A) An anteroposterior view of the right knee obtained ateen the tibial and femoral component by complete wear ofview of the right knee obtained 8 days after the revisionprosthesis. (C) A retrieval specimen of the medial tibial

of the medial meniscal bearing.

Table 3. Complications in the AMK and LCS Group

arameters AMK LCS

omplete wear of tibial bearingpolyethylene

3 knees (5%) 3 knees (5%)

islocation of medial tibialmeniscal bearing

0 knee (0%) 1 knee (2%)

evere osteolysis in the femoralcondyles (N1 × 1 cm)

1 knee (2%) 0 knee (0%)

ild osteolysis in proximalmedial tibia (b0.5 × 0.5 cm)

6 knees (10%) 4 knees (7%)

fection 1 knee (2%) 1 knee (2%)kin edge necrosis 3 knees (5%) 3 knees (5%)


postoperative knee and functional scores and rangeof motion of knees in patients with or withoutprevious arthroscopic surgery were not significantlydifferent (P N .05).Patient's satisfaction was similar in both groups.

In the AMK group, 37 patients (61%) were fullysatisfied with the outcome of the operation, 21patients (34%) were satisfied, and 6 patients(10%) were dissatisfied. In the LCS group, 34patients (56%) were fully satisfied with the out-come of the operation, 24 patients (39%) weresatisfied, and 6 patients (10%) were dissatisfied. Ofthe 6 patients in the AMK group who weredissatisfied, 1 patient had constant moderate painand stiffness and the remaining 5 patients under-went revision of TKAs for polyethylene wear,osteolysis, or infection. Of the 6 patients in theLCS group who were dissatisfied, 1 patient hadconstant pain and the remaining 5 patients under-went revision of TKAs for polyethylene wear,dislocated tibial bearing, or infection.Activity level of the patients was improved very

much after the operation. Many patients were quiteactive despite the usual cautions to avoid activitiesinvolving impact after TKA. Nearly 40% (24patients) of the 61 patients had an activity score of5 or 6 points at the latest follow-up examination,indicating participation in strenuous farm work (ascore of 5 points) or participation in tennis (a scoreof 6 points). Regular walking for exercise, for adistance of 3.2 km a day for example, was the mostcommon activity (48 patients, 79%). Use of either astationary or a conventional bicycle was the secondmost common activity (41 patients, 67%). Otheractivities included playing golf (15 patients, 25%),aerobics (14 patients, 23%), playing tennis (9patient, 15%), mountain hiking (7 patients, 11%),and farm work (26 patients, 43%).The radiographic results and prevalence of osteo-

lysis were not significantly different between thetwo groups (Table 2). In the AMK group, 3 knees(5%) were revised because of complete wear of thetibial polyethylene bearing but no osteolysis and 1knee (2%) was revised because of severe osteolysisin the femoral condyles (Fig. 1). Small osteolysis lessthan 5 × 5 mm was identified in both radiographsand CT scans in 6 knees (10%). One knee (2%) wasrevised because of infection. In the LCS group, 3knees (5%) were revised because of complete wearof the medial tibial polyethylene bearing but noosteolysis (Fig. 2) and 1 knee (2%) was revisedbecause of dislocation of the medial tibial meniscalbearing. No knee was revised for osteolysis in theLCS group. Small osteolysis (5 × 5 mm) wasidentified in both radiographs and CT scans in 4

P

C

D

S

M

InS

knees (7%). One knee (2%) was revised forinfection. The patients with an infected knee inboth groups were not the same patients.

The Kaplan-Meier survivorship [20] revealed91% survival of knee prosthesis in both groups at12 years (95% confidence interval, 0.93-0.98) withuse of all reasons for failure: aseptic loosening,infection, polyethylene failure, or osteolysis.

Complications

Three knees (5%) in each group had completewear of the tibial polyethylene bearing.

One knee (2%) in the mobile-bearing TKA haddislocation of the medial tibial meniscal bearing.

One knee (2%) in the fixed-bearing TKA hadsevere osteolysis in the femoral condyles.

Six knees (10%) in the fixed-bearing TKA andfour knees (7%) in the mobile-bearing TKA hadmild osteolysis in the proximal medial tibia.

Three knees (5%) in each group had a skinedge necrosis, which was treated with debride-ment and closure.

One knee (2%) in each group was revised becauseof infection (Table 3).

Discussion

We were not able to prove our hypothesis thatthe mobile-bearing TKA would improve the clinicaland radiographic results, patient satisfaction, andpatient activity level in these young patients withbilateral TKAs. Clinical and radiographic resultswere good in both groups. Clinical and radio-graphic outcomes were not different between thepatients with or without previous arthrosopicsurgery [21]. We believe that several factors wereresponsible for the good results in both fixed- andmobile-bearing groups: good cementing techniqueusing a pulsatile lavage and cement pressurization,creation of equal flexion and extension gaps,


preservation of the joint line and posterior femoralcondylar offset, proper ligament balancing, as wellas small and light patients.However, it is clear from our data that there was

one dislocation that required surgery in the mobilemeniscal-bearing group. On the contrary, in thefixed-bearing group, there was no reoperation fordislodgement of the bearing. With regard to bearingdislocation, the fixed-bearing group is better thanthe mobile meniscal-bearing group.The limitation of the current study is the relatively

light weight of the patients who were mostly femaleand who may not have provided sufficient stress tothe implant surfaces and interfaces to demonstrate adifference between the two designs despite the longfollow-up.The merits of this study include the fact that it was

based on one surgeon's experience with a consecu-tive group of patients and that data on bilateralsimultaneous primary TKAs in the same patientswere collected prospectively. Other merit was thattherewas no bias involved in the selection of patientsfor treatment with the AMK fixed-bearing or LCSmeniscal-bearing prosthesis. Additional merit wasthat fluoroscopic x-ray examinations and CT scan-ning were used to determine osteolysis critically.Functional improvement was assessed further

with the use of the activity score of Tegner andLysholm [19]. All but three patients in eachgroup, who had worse scores, had an improvedactivity score at the latest follow-up examinationcompared with preoperative score. In addition, 24patients (39%) had a score of at least 5 points,indicating regular participation in such activity astennis, cycling, or strenuous farm or constructionwork. Despite the patients' active lifestyles, loos-ening of the components or osteolysis thatnecessitated revision was not a notable problemin this series.We were not able to prove the hypothesis that

mobile-bearing TKAs would result in lower pre-valence of osteolysis than fixed-bearing TKAs. Fail-ure due to wear or osteolysis in young patients hasbeen reported at very low rates in clinical series offixed-bearing and mobile-bearing TKAs and hasshown no difference in the rate of wear andperiprosthetic osteolysis between fixed-bearingand mobile-bearing TKAs [14-17,22-30]. Theresults of the current study confirmed that theprevalence of periprosthetic osteolysis was verylow in both groups.Collier et al [30] analyzed the risk factors for

osteolysis. Men were 3.6 times more likely to haveosteolysis than women. Knees in which the base-plate had a grit-blasted proximal surface were 2.6

times more likely to be affected by osteolysis thanknees treated with a polished-surface baseplate.Knees with an insert that had been γ irradiated in airwere 4.0 times more likely to have osteolysis thanknees with an insert that had been γ irradiated innitrogen. The risk of osteolysis increased by a factorof 1.5 with any 1.0-year increase in the shelf age ofthe insert. Also, the intercomponent hyperextensionangle was significantly associated with osteolysis.

Our findings of low prevalence of osteolysis in bothgroups in this series may be related to the use ofcobalt-chromium tibial baseplate (stiff cobalt-chro-mium plate maintains even load distribution for thepolyethylene); polished proximal surface of tibialbaseplate; sterilization with γ irradiation in vacuum;improved quality of polyethylene of insert; short shelfage of insert; absence of access channels for weardebris; no intercomponent hyperextension; andfemale patients. Also, it is possible that rate ofosteolysis was low because the follow-up was notlong enough. A mobile-bearing design is not asso-ciated with a lower prevalence of osteolysis than awell-designed, fixed-bearing TKA at mid-term; itremains to be proven at a longer-term follow-up.

Reported rates of dislocation or subluxation withbicompartmental meniscal-bearing devices have ran-ged between 2.2% [15] and 7.6% [31,32]. Manyauthors have emphasized good surgical technique toavoid bearing dislocation, especially balancing offlexion and extension gaps [27,32,33]. In the currentseries, one knee had a dislocation of the medial tibialbearing after a removal of Baker's cyst. We theorizethat the posterior cruciate ligament was damaged inthis knee while the Baker's cyst was removed, andanteroposterior instability of the knee led to disloca-tion of the medial tibial bearing.

Broken bearings appear to be more commonwith meniscal-bearing knee prostheses that usedcurved tracks without stops. Of the 16 patients inone series [2], 4 (25%) had broken lateralmeniscal bearings, compared with 7 (1.5%) in alarger series of 473 patients [15]. The authorstheorized that the bearing breakage was due toposterior subluxation of the bearing and entrap-ment between the femoral component and theposterior edge of the bearing track. In the currentseries, 1 knee had a breakage of the medial tibialbearing and the reason for this is not known. Wetheorize that a slight varus alignment of the kneeled to stress concentration on the medial tibialbearing and subsequently developed a breakage ofthe medial tibial polyethylene bearing.

Differentiation of knee score between the knees inthe same patient posed some difficulties. Thecomponents of pain, support, and range of motion


were easily differentiated between knees. In con-trast, the components of distance walked, stairclimbing, and activity score were more difficult todifferentiate. In these domains, even if the patientshad difficulties, they could always identify the kneewhich limited their activities.In conclusion, the study has demonstrated no

difference between fixed-bearing and mobile-bear-ing TKAs in young and active patients in terms ofosteolysis, wear, and aseptic loosening, and that theincreased cost associated with mobile-bearing TKAis not justified. There was only 1 bearing dislocationin a mobile-bearing TKA in this series, but othershave reported a higher incidence.

References

1. Colizza WA, Insall JN, Scuderi GR. The posteriorstabilized total knee prosthesis assessment of poly-ethylene damage and osteolysis after a ten-year-minimum followup. J Bone Joint Surg Am 1995;77:1713.

2. Ranawat CS, Boachie-Adjei O. Survivorship analysisand results of total condylar knee arthroplasty: eight-to 11-year followup period. Clin Orthop Relat Res1988;226:6.

3. Rand JA, Ilstrup DM. Survivorship analysis of totalknee arthroplasty: cumulative rates of survival of9200 total knee arthroplasties. J Bone Joint Surg Am1991;73:397.

4. Schai PA, Thornhill TS, Scott RD. Total kneearthroplasty with the PFC system: results at aminimum of ten year and survivorship analysis.J Bone Joint Surg Br 1998;80:850.

5. Scott WN, Rubinstein M, Scuderi GR. Results afterknee replacement with a posterior cruciate–substitut-ing prosthesis. J Bone Joint Surg Am 1988;70:1163.

6. Scott RD, Volatile TB. Twelve years' experience withposterior cruciate–retaining total knee arthroplasty.Clin Orthop Relat Res 1986;205:100.

7. Scuderi GR, Insall JN. Total knee arthroplasty: currentclinical perspectives. Clin Orthop Relat Res 1992;276:26.

8. Stern SH, Insall JN. Posterior stabilized prosthesis:results after followup of nine to twelve years. J BoneJoint Surg Am 1992;74:980.

9. Vince KG, Insall JN, Kelly MA. The total condylarprosthesis: 10- to 12-year results of a cemented kneereplacement. J Bone Joint Surg Br 1989;71:793.

10. Wasielewski RC, Parks N,Williams I, et al. Tibial insertundersurface as a contributing source of polyethylenewear debris. Clin Orthop Relat Res 1997;345:53.

11. Puloski SK, McCalden RW, Mac Donald SJ, et al.Tibial post wear in posterior stabilized total kneearthroplasty. An unrecognized source of polyethylenedebris. J Bone Joint Surg Am 2001;83:390.

12. Engh GA, Ammeen DJ. Periprosthetic osteolysis withtotal knee arthroplasty. Instr Course Lect 2001;50:391.

13. Insall JN. Adventures in mobile-bearing knee design:a mid-life crisis. Orthopedics 1998;21:1021.

14. Buechel FF, Pappas MJ. Long-term survivorshipanalysis of cruciate-sparing versus cruciate-sacrificingknee prosthesis using meniscal bearings. Clin OrthopRelat Res 1990;260:162.

15. Jordan LR, Olivo JL, Voorhorst PE. Survivorshipanalysis of cementless meniscal bearing total kneearthroplasty. Clin Orhop 1997;338:119.

16. Ritter MA, Campbell E, Faris PM, et al. Long-termsurvival analysis of the posterior cruciate condylar totalknee arthroplasty: a 10-year evaluation. J Arthroplasty1989;4:293.

17. Insall JN, Dorr LD, Scott RD, et al. Rationale of theKnee Society clinical rating system. Clin Orthop RelatRes 1989;248:13.

18. Insall JN, Ranawat CS, Aglietti P, et al. A comparisonof four models of total knee-replacement prostheses.J Bone Joint Surg Am 1976;58:754.

19. Tegner Y, Lysholm J. Rating systems in the evaluation ofknee ligament injuries. ClinOrthopRelatRes1985;198:43.

20. Kaplan EL, Meier R. Nonparametric estimation fromin complete observations. J Am Statist Assoc 1958;53:457.

21. Diduch DR, Insall JN, Scott JN, et al. Total kneereplacement in young, active patients: long-termfollow-up and functional outcome. J Bone JointSurg Am 1997;79:578.

22. Ranawat CS, Padgett DE, Ohasi Y. Total kneearthroplasty for patients younger than 55 years. ClinOrthop Relat Res 1989;248:27.

23. Lonner JH, Hershman S, Mont M, et al. Total kneearthroplasty in patients 40 years of age and youngerwith osteoarthritis. Clin Orthop Relat Res 2000;380:85.

24. Sorrels RB. The rotating platform mobile bearingTKA. Orthopedics 1996;19:793.

25. Callaghan JJ, Squire MW, Goetz DD, et al. Cementedrotating-platform total knee replacement: a nine totwelve-year follow-up study. J Bone Joint Surg Am2000;82:705.

26. Kaper BP, Smith PN, Bourne RB, et al. Medium termresults of a mobile bearing total knee replacement.Clin Orthop Relat Res 1999;369:201.

27. Buechel Sr FF, Buechell Jr FF, Pappas MJ, et al.Twenty-year evaluation of meniscal bearing androtating platform knee replacements. Clin OrthopRelat Res 2001;388:41.

28. Font-Rodriquez DE, Scuderi GR, Insall JN. Survivor-ship of cemented total knee arthroplasty. Clin OrthopRelat Res 1997;345:79.

29. Kim YH, Koo HK, Kim JS. Comparison of fixed-bearing and mobile-bearing total knee arthroplasties.Clin Orthop Relat Res 2001;392:101.

30. Collier MB, Engh Jr CA, Mcauley JP, et al. Osteolysisafter total knee arthroplasty: influence of tibial base-plate surface finish and sterilization of polyethylene


insert. Findings at five to ten years postoperatively.J Bone Joint Surg Am 2005;87:2702.

31. Insall JN, Aglietté P, Baldini A, et al. Meniscal-bearingknee replacement. In: Insall JN, Scott WN, editors.Surgery of the knee. 3rd ed. New York: ChurchillLivingston; 2001. p. 1717.

32. Walker PS. Requirements for successful total kneereplacements: design considerations. Orthop ClinNorth Am 1989;20:15.

33. Bert JM. Dislocation/subluxation of meniscal bearingelements after New Jersey low-contact stress total kneearthroplasty. Clin Orthop Relat Res 1990;254:211.

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Prevalence of Osteolysis After Simultaneous Bilateral Fixed- and Mobile-Bearing Total Knee Arthroplasties in Young Patients