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Early tibial tray failure of a duracon knee with retrieval analysis1
The Journal of Arthroplasty Vol. 19 No. 6 2004
Case Report
Early Tibial Tray Failure of a Duracon Knee With Retrieval Analysis Ta-Feng Ho, MD*, Ruey-Yug Tsai, PhD,† Pei-Yuan Lee, MD,* and Ming-Chou Ku, MD, MSc (Orth)*
Abstract: We report a case of early tibial tray fracture of a Duracon knee prosthesis. Aside from the clinical, radiographic, and gross analysis of the failed prosthesis, we also performed analysis on the retrieved polyethylene component and the fractured tibial baseplate. In the analyses, we noted significant femoral component malalignment, uneven tray cementation, and inherent metallurgical weakness. It appears that the high compressive load on the medial tray resulted in bending fatigue failure. To avoid this complication, it is important to restore the normal alignment of the knee joint and use a polyethylene insert of higher conformity, at least 6 mm thick. Key words: knee, arthroplasty, tibial tray, fracture, wear, complication. © 2004 Elsevier Inc. All rights reserved.
Polyethylene (PE) insert wear is the major aseptic failure in total knee arthroplasty (TKA), but metal tibial tray breakage is a relatively rare complication, with only 1% to 2% of cases reported in a 10-year follow-up study [1]. Nevertheless, it is the most common cause of early aseptic failure requiring revision surgery after Kinematic Condylar knee arthroplasty (Howmedica, Rutherford, NJ) [2]. Past literature shows that many clinical, surgical, metallurgical, and design implications should be considered [1– 4].
We herein report a case of early tibial tray failure of a Duracon knee prosthesis (Howmedica). There is no such failure of these Howmedica products after the previous design problems were corrected [2]. Although the forged cobalt-chromiummolybdenum alloy (Vitallium, Howmedica) is inherent with superior tensile and fatigue properties as a result of the fine-grain structure and the highdegree chemical homogeneity [5], in vivo stress concentration or metallurgical defect may be responsible for the early failure. PE surface analysis, polaroscopy, metal fracturography, and metallography were performed to clarify what caused the complication.
From the *Department of Orthopaedics Surgery, Show Chwan Memorial Hospital, Changhua City, Changhua County, Taiwan; and the †Institute of Biomedical Engineering, Yang Ming University, Taipei, Taiwan. Submitted September 30, 2002; accepted February 1, 2004. No benefits or funds were received in support of this study. Reprint requests: Ta-Feng Ho, MD, Department of Orthopaedics Surgery, Show Chwan Memorial Hospital, 542, Section 1, Chung-Shang Road, 500 Changhua City, Changhua County, Taiwan. © 2004 Elsevier Inc. All rights reserved. 0883-5403/04/1906-0022$30.00/0 doi:10.1016/j.arth.2004.02.044
Case Report A 73-year-old woman came to the outpatient clinic complaining of protracted right knee pain for 2 months. It became worse during stance phase. The index TKA (Howmedica, Duracon) was performed 3 years before presentation. She was 155
797
798 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
Fig. 1. The failed TKA before revision surgery. The arrow indicates the location of the osteolysis.
cm tall and weighed 78 kg. Clinically, she walked with a limp and a varus thrust. Examination of the knee indicated some joint effusion and tenderness along the medial joint line with local heat. Erythrocyte sedimentation rate, C-reactive protein, and white cell count all were within normal limits. Roentgenographically, the femorotibial angle was in 8° varus, and the femoral component was in 3° varus. The medial space between the components had almost disappeared, and a focal osteolytic reaction was found beneath the posterior portion of the medial tibial tray. No evidence of stress shielding was observed around the proximal tibia (Fig. 1). The patellofemoral alignment was appropriate in the Merchant view. Under the impression of a failed prosthesis caused by malalignment and severe polyethylene wear, revision surgery was performed. During surgery, significant synovial proliferation with embedded polyethylene chips was observed in the knee cavity, without evidence of metallosis reaction. After the worn polyethylene was removed, unexpected breakage was found over the posteromedial (PM) portion of the metal tibial tray. Focal bone deficit lay under this area of the tray, corresponding to the osteolytic reaction noted from the radiographic film; however, the metaphyseal cortical shell structure of the tibia was preserved. All the collateral ligaments were intact. A posterior stabilizer–type TKA was implanted (Fig. 2), and knee function returned to normal. No further complaint has been noted during the 2-year follow-up since revision surgery. Visual observation of the retrieved components revealed several notable characteristics of the tray
Fig. 2. Postrevision films.
and PE insert. There was no previously criticized slot surrounding the tray stem, the sharp corner of the cruciate recess, or the small radius of the tray [6,7]. A crack was located between the medial corner of the posterior cruciate ligament (PCL) recess and the anteromedial (AM) aspect of the tray, and a secondary crack line had developed near the elevated edge of the AM tray (Fig. 3). The breakage surface was complex instead of regular fracture waves. A focal stair-step pattern could be observed grossly (Fig. 4). The cement mantle underlying the tibial tray was not destroyed during surgery. Uneven tray cementation surrounding the crack was evident on the undersurface of the tray (Fig. 5). No corresponding scratch marks were observed over the surface of the medial femoral condyle. Regarding the metal tray, fracturography by scanning electron microscopy (SEM) (Leica Stereoscan 360, Cambridge, UK) showed beach marks
Fig. 3. The fractured tibial tray. The arrow indicates the secondary crack line.
Early Duracon Tibial Tray Failure • Ho et al.
799
Fig. 4. The surface of the tray fracture. A gross stairstep pattern is noted in the middle. The arrow indicates where SEM images were taken.
and fatigue striations (Fig. 6). From the anteroposterior direction, the propagation of beach marks was compatible with the gross observation of fracture-line development (Fig. 4). This observation supported the possible development of a fracture line, started at the medial corner of the PCL recess, where osteolysis, downward compression force, and inherent structural weakness (the corner) met. The microstructure of the metal tray was examined after electrolytic etching in concentrated hydrochloric acid. The metallography (Fig. 7) revealed grain growth, averaging 1 to 2 mm in size, along the undersurface of the tray. No dissolution of interdendritic carbides, mass precipitation of lamellar carbide eutectic phases at grain boundary, or localized porosity from incipient melting was noted.
Fig. 5. A region of uneven cement mantle under the tibial tray. The fracture line passes through it.
As for the PE insert (Fig. 8), surface analysis was performed with a 10 ⫻ light stereomicroscope (Leica MZ6, Wetzlar, Germany). There was a deep depression on the PM portion and 2 marked laminations at the anterolateral region. The deep depression, located near the path of the fracture, was surrounded by a burnished area. Creeps were noted at the component edge near the deep depression. The mean surface-damage score [8] was 55, as measured by the first 2 authors. Polaroscopy (Leica DM RX [HCS POL]) of the PE component was performed on specimens of 30-m thickness (Shandon M1R, Pittsburgh, PA). No subsurface demarcation line that indicates heat-press processing is noted by polaroscopy [9].
800 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
Fig. 6. SEM observation of the fracture. Fatigue waves propagate posteroanteriorly (Original magnification ⫻ 50.)
Discussion Many cases of early tibial tray breakage have been reported in the literature [2,7,10,11]. In one series of 1,017 Kinematic knees, 16 (1.6%) were revised for fracture of the tibial tray [2]. The tray slot, the sharp corner of the cruciate recess, and a
Fig. 7. Metallography presenting fine-grain structure of the tray undersurface and grain growth beneath the surface, representing the interior microstructure.
small radius between the tray and its rim are assumed to be the design weakness causing the failure [6,7]. In the later Kinemax system (Howmedica), the design defects were eradicated by making the base-plate thicker and stronger, using a forged alloy, Vitallium [2]. The forging process brought superior tensile strength and fatigue resis-
Early Duracon Tibial Tray Failure • Ho et al.
801
ment was considered relevant to the complication [3,16]. In metallurgy, end-to-end variation in grain size in any direction in forged Vitallium renders the material susceptible to failure [5]. The sintering process introduces a tiny notch on the undersurface of the implant and variation in the grain sizing between the interior and the surface [18]. The fatigue strength of the material is accordingly decreased by 16% [19], contributing to the metal tray failure [3,20]. In our case, only grain-growth phenomenon caused by the sintering process was found. Metallurgically, the tray is sound. Fig. 8. Surface of the PE component.
tance to the base-plate, because it allowed for a fine-grain structure and a high degree of chemical homogeneity [5]. In addition, the increase of femorotibial contact area was found to be beneficial in lowering the surface stress of the PE insert [12]. No such complications have been reported for the Duracon knee. In our case, the thickness of the worn insert was acceptable according to the criterion set by Collier [12]. Therefore, other etiologies should be considered. From gross observation, the crack originated in the medial corner of the PCL recess of the tray. A secondary fracture line developed when the breakage encountered geographic change (elevated rim of the tray). SEM images confirmed this observation. From the vertical direction, the tray undersurface (tension side) failed first, and the crack propagated upward. It is well known that compression load is applied to the tray during weight-bearing. Because of medialization of the knee center during stance phase [13], more compression stress (60% and 80%) is applied on the medial knee [14]. The varus positioning of the femoral component and changed kinematics of the cruciate-retaining prosthesis [15] exacerbated the loading along the PM region of the insert, especially during flexion [14]. Besides, the PE wear pattern shows the in vivo rotational-subluxation kinematics [16]. Remarkable depression of the focal PE developed once the superficial delaminated fragment detached because of altered kinematics, sliding instead of rolling [17]. Subsequent trapping of the femorotibial articulation occurred. As evidenced by associated, uneven tray cementation, the osteolysis, and an intact metaphyseal shell, it appears that bending fatigue took place. Neither obesity nor patellofemoral malalign-
Conclusion This report presents a rare case of early aseptic TKA failure caused by tibial metal tray breakage. The failure mode of the metal clearly is bending cantilever fatigue, pattern IV of McNeice and Gruen [21]. Increased stress with ensuing failure is attributable to the femoral component malpositioning, uneven tray cementation, and inherent metallurgical weakness. To avoid similar complications, it is vital to restore the normal mechanical axis during TKA, rotate the femoral component externally when using a classical alignment method [4], and perform a sound cementation technique [22]. In addition, guidelines proposed by Bartel et al [23] should be followed.
References 1. Mason MD, Ewald FC, Wright J, et al: 10-13 year review of a non-constrained cruciate retaining total knee. Orthop Proc 17:1091, 1994 2. Abernethy PJ, Robinson CM, Fowler RM: Fracture of the metal tibial tray after Kinematic total knee replacement. J Bone Joint Surg Br 78:220, 1996 3. Morrey BF, Chao EYS: Fracture of the porous-coated metal tray of a biologically fixed knee prosthesis. Clin Orthop 228:182, 1988 4. Altintas F, Sener N, Ugutmen E: Fracture of the tibial tray after total knee arthroplasty. J Arthroplasty 14: 112, 1999 5. Miller EH, Shastri R, Shih CI: Fracture failure of a forged Vitallium prosthesis. J Bone Joint Surg Am 64:1359, 1982 6. Ahir SP, Blunn GW, Haider H, et al: Evaluation of a testing method for the fatigue performance of total knee tibial trays. J Biomechanics 32:1049, 1999 7. Maruyama M, Terayama K, Sunohara H, et al: Fracture of the tibial tray following PCA knee replacement. Arch Orthop Trauma Surg 113:330, 1994 8. Hood RW, Wright TM, Burstein AH: Retrieval anal-
802 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
9.
10. 11.
12.
13.
14. 15.
16.
ysis of total knee prostheses: a method and its application to 48 total condylar prostheses. J Biomed Mater Res 17:829, 1983 Bloebaum RD, Nelson K, Dorr LD, et al: Investigation of early surface delamination observed in retrieved hear-pressed tibial inserts. Clin Orthop 269:120, 1991 Flivik G, Ljung P, Rydholm U: Fracture of the tibial tray of the PCA knee. Acta Orthop Scand 61:26, 1990 Fradisar IA, Hoffmann ML, Askew MJ: Fracture of a fenestrated metal backing of a tibial knee component. J Arthroplasty 4:27, 1989 Collier JP, Mayor MB, McNamara JL, et al: Analysis of the failure of 122 polyethylene inserts from uncemented tibial knee components. Clin Orthop 273: 232, 1991 Harrington IJ: Static and dynamic loading patterns in knee joints with deformities. J Bone Joint Surg Am 65:247, 1983 Cameron HU: Tibial component wear in total knee replacement. Clin Orthop 309:29, 1994 Lewis P, Rorabeck CH, Bourne RB, et al: Posteromedial tibial polyethylene failure in total knee replacements. Clin Orthop 299:11, 1994 Wasielewski RC, Galante JO, Leighty RM, et al: Wear patterns on retrieved polyethylene tibial inserts and
17.
18.
19.
20.
21.
22.
23.
their relationship to technical considerations during total knee arthroplasty. Clin Orthop 299:31, 1994 Blunn GW, Joshi AB, Minns RJ, et al: Wear in retrieved condylar knee arthroplasties. J Arthroplasty 12:281, 1997 Jacobs JJ, Latanision RM, Rose RM, et al: The effect of porous coating processing on the corrosion behavior of cast Co-Cr-Mo surgical implant alloys. J Orthop Res 8:874, 1990 Pilliar RM: Powder metal made orthopedic implants with porous surface for fixation by tissue ingrowth. Clin Orthop 176:42, 1983 Ranawat CS, Johanson NA, Rimnac CM, et al: Retrieval analysis of porous-coated components for total knee arthroplasty. Clin Orthop 209:244, 1986 Gruen TA, McNeice GM, Amstutz HC: “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop 141:17, 1979 Norton MR, Eyres KS: Irrigation and suction technique to ensuer reliable cement penetration for total knee arthroplasty. J Arthroplasty 15:468, 2000 Bartel DL, Bicknell VL, Wright VA: The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement. J Bone Joint Surg Am 68:1041, 1986
Case Report
Early Tibial Tray Failure of a Duracon Knee With Retrieval Analysis Ta-Feng Ho, MD*, Ruey-Yug Tsai, PhD,† Pei-Yuan Lee, MD,* and Ming-Chou Ku, MD, MSc (Orth)*
Abstract: We report a case of early tibial tray fracture of a Duracon knee prosthesis. Aside from the clinical, radiographic, and gross analysis of the failed prosthesis, we also performed analysis on the retrieved polyethylene component and the fractured tibial baseplate. In the analyses, we noted significant femoral component malalignment, uneven tray cementation, and inherent metallurgical weakness. It appears that the high compressive load on the medial tray resulted in bending fatigue failure. To avoid this complication, it is important to restore the normal alignment of the knee joint and use a polyethylene insert of higher conformity, at least 6 mm thick. Key words: knee, arthroplasty, tibial tray, fracture, wear, complication. © 2004 Elsevier Inc. All rights reserved.
Polyethylene (PE) insert wear is the major aseptic failure in total knee arthroplasty (TKA), but metal tibial tray breakage is a relatively rare complication, with only 1% to 2% of cases reported in a 10-year follow-up study [1]. Nevertheless, it is the most common cause of early aseptic failure requiring revision surgery after Kinematic Condylar knee arthroplasty (Howmedica, Rutherford, NJ) [2]. Past literature shows that many clinical, surgical, metallurgical, and design implications should be considered [1– 4].
We herein report a case of early tibial tray failure of a Duracon knee prosthesis (Howmedica). There is no such failure of these Howmedica products after the previous design problems were corrected [2]. Although the forged cobalt-chromiummolybdenum alloy (Vitallium, Howmedica) is inherent with superior tensile and fatigue properties as a result of the fine-grain structure and the highdegree chemical homogeneity [5], in vivo stress concentration or metallurgical defect may be responsible for the early failure. PE surface analysis, polaroscopy, metal fracturography, and metallography were performed to clarify what caused the complication.
From the *Department of Orthopaedics Surgery, Show Chwan Memorial Hospital, Changhua City, Changhua County, Taiwan; and the †Institute of Biomedical Engineering, Yang Ming University, Taipei, Taiwan. Submitted September 30, 2002; accepted February 1, 2004. No benefits or funds were received in support of this study. Reprint requests: Ta-Feng Ho, MD, Department of Orthopaedics Surgery, Show Chwan Memorial Hospital, 542, Section 1, Chung-Shang Road, 500 Changhua City, Changhua County, Taiwan. © 2004 Elsevier Inc. All rights reserved. 0883-5403/04/1906-0022$30.00/0 doi:10.1016/j.arth.2004.02.044
Case Report A 73-year-old woman came to the outpatient clinic complaining of protracted right knee pain for 2 months. It became worse during stance phase. The index TKA (Howmedica, Duracon) was performed 3 years before presentation. She was 155
797
798 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
Fig. 1. The failed TKA before revision surgery. The arrow indicates the location of the osteolysis.
cm tall and weighed 78 kg. Clinically, she walked with a limp and a varus thrust. Examination of the knee indicated some joint effusion and tenderness along the medial joint line with local heat. Erythrocyte sedimentation rate, C-reactive protein, and white cell count all were within normal limits. Roentgenographically, the femorotibial angle was in 8° varus, and the femoral component was in 3° varus. The medial space between the components had almost disappeared, and a focal osteolytic reaction was found beneath the posterior portion of the medial tibial tray. No evidence of stress shielding was observed around the proximal tibia (Fig. 1). The patellofemoral alignment was appropriate in the Merchant view. Under the impression of a failed prosthesis caused by malalignment and severe polyethylene wear, revision surgery was performed. During surgery, significant synovial proliferation with embedded polyethylene chips was observed in the knee cavity, without evidence of metallosis reaction. After the worn polyethylene was removed, unexpected breakage was found over the posteromedial (PM) portion of the metal tibial tray. Focal bone deficit lay under this area of the tray, corresponding to the osteolytic reaction noted from the radiographic film; however, the metaphyseal cortical shell structure of the tibia was preserved. All the collateral ligaments were intact. A posterior stabilizer–type TKA was implanted (Fig. 2), and knee function returned to normal. No further complaint has been noted during the 2-year follow-up since revision surgery. Visual observation of the retrieved components revealed several notable characteristics of the tray
Fig. 2. Postrevision films.
and PE insert. There was no previously criticized slot surrounding the tray stem, the sharp corner of the cruciate recess, or the small radius of the tray [6,7]. A crack was located between the medial corner of the posterior cruciate ligament (PCL) recess and the anteromedial (AM) aspect of the tray, and a secondary crack line had developed near the elevated edge of the AM tray (Fig. 3). The breakage surface was complex instead of regular fracture waves. A focal stair-step pattern could be observed grossly (Fig. 4). The cement mantle underlying the tibial tray was not destroyed during surgery. Uneven tray cementation surrounding the crack was evident on the undersurface of the tray (Fig. 5). No corresponding scratch marks were observed over the surface of the medial femoral condyle. Regarding the metal tray, fracturography by scanning electron microscopy (SEM) (Leica Stereoscan 360, Cambridge, UK) showed beach marks
Fig. 3. The fractured tibial tray. The arrow indicates the secondary crack line.
Early Duracon Tibial Tray Failure • Ho et al.
799
Fig. 4. The surface of the tray fracture. A gross stairstep pattern is noted in the middle. The arrow indicates where SEM images were taken.
and fatigue striations (Fig. 6). From the anteroposterior direction, the propagation of beach marks was compatible with the gross observation of fracture-line development (Fig. 4). This observation supported the possible development of a fracture line, started at the medial corner of the PCL recess, where osteolysis, downward compression force, and inherent structural weakness (the corner) met. The microstructure of the metal tray was examined after electrolytic etching in concentrated hydrochloric acid. The metallography (Fig. 7) revealed grain growth, averaging 1 to 2 mm in size, along the undersurface of the tray. No dissolution of interdendritic carbides, mass precipitation of lamellar carbide eutectic phases at grain boundary, or localized porosity from incipient melting was noted.
Fig. 5. A region of uneven cement mantle under the tibial tray. The fracture line passes through it.
As for the PE insert (Fig. 8), surface analysis was performed with a 10 ⫻ light stereomicroscope (Leica MZ6, Wetzlar, Germany). There was a deep depression on the PM portion and 2 marked laminations at the anterolateral region. The deep depression, located near the path of the fracture, was surrounded by a burnished area. Creeps were noted at the component edge near the deep depression. The mean surface-damage score [8] was 55, as measured by the first 2 authors. Polaroscopy (Leica DM RX [HCS POL]) of the PE component was performed on specimens of 30-m thickness (Shandon M1R, Pittsburgh, PA). No subsurface demarcation line that indicates heat-press processing is noted by polaroscopy [9].
800 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
Fig. 6. SEM observation of the fracture. Fatigue waves propagate posteroanteriorly (Original magnification ⫻ 50.)
Discussion Many cases of early tibial tray breakage have been reported in the literature [2,7,10,11]. In one series of 1,017 Kinematic knees, 16 (1.6%) were revised for fracture of the tibial tray [2]. The tray slot, the sharp corner of the cruciate recess, and a
Fig. 7. Metallography presenting fine-grain structure of the tray undersurface and grain growth beneath the surface, representing the interior microstructure.
small radius between the tray and its rim are assumed to be the design weakness causing the failure [6,7]. In the later Kinemax system (Howmedica), the design defects were eradicated by making the base-plate thicker and stronger, using a forged alloy, Vitallium [2]. The forging process brought superior tensile strength and fatigue resis-
Early Duracon Tibial Tray Failure • Ho et al.
801
ment was considered relevant to the complication [3,16]. In metallurgy, end-to-end variation in grain size in any direction in forged Vitallium renders the material susceptible to failure [5]. The sintering process introduces a tiny notch on the undersurface of the implant and variation in the grain sizing between the interior and the surface [18]. The fatigue strength of the material is accordingly decreased by 16% [19], contributing to the metal tray failure [3,20]. In our case, only grain-growth phenomenon caused by the sintering process was found. Metallurgically, the tray is sound. Fig. 8. Surface of the PE component.
tance to the base-plate, because it allowed for a fine-grain structure and a high degree of chemical homogeneity [5]. In addition, the increase of femorotibial contact area was found to be beneficial in lowering the surface stress of the PE insert [12]. No such complications have been reported for the Duracon knee. In our case, the thickness of the worn insert was acceptable according to the criterion set by Collier [12]. Therefore, other etiologies should be considered. From gross observation, the crack originated in the medial corner of the PCL recess of the tray. A secondary fracture line developed when the breakage encountered geographic change (elevated rim of the tray). SEM images confirmed this observation. From the vertical direction, the tray undersurface (tension side) failed first, and the crack propagated upward. It is well known that compression load is applied to the tray during weight-bearing. Because of medialization of the knee center during stance phase [13], more compression stress (60% and 80%) is applied on the medial knee [14]. The varus positioning of the femoral component and changed kinematics of the cruciate-retaining prosthesis [15] exacerbated the loading along the PM region of the insert, especially during flexion [14]. Besides, the PE wear pattern shows the in vivo rotational-subluxation kinematics [16]. Remarkable depression of the focal PE developed once the superficial delaminated fragment detached because of altered kinematics, sliding instead of rolling [17]. Subsequent trapping of the femorotibial articulation occurred. As evidenced by associated, uneven tray cementation, the osteolysis, and an intact metaphyseal shell, it appears that bending fatigue took place. Neither obesity nor patellofemoral malalign-
Conclusion This report presents a rare case of early aseptic TKA failure caused by tibial metal tray breakage. The failure mode of the metal clearly is bending cantilever fatigue, pattern IV of McNeice and Gruen [21]. Increased stress with ensuing failure is attributable to the femoral component malpositioning, uneven tray cementation, and inherent metallurgical weakness. To avoid similar complications, it is vital to restore the normal mechanical axis during TKA, rotate the femoral component externally when using a classical alignment method [4], and perform a sound cementation technique [22]. In addition, guidelines proposed by Bartel et al [23] should be followed.
References 1. Mason MD, Ewald FC, Wright J, et al: 10-13 year review of a non-constrained cruciate retaining total knee. Orthop Proc 17:1091, 1994 2. Abernethy PJ, Robinson CM, Fowler RM: Fracture of the metal tibial tray after Kinematic total knee replacement. J Bone Joint Surg Br 78:220, 1996 3. Morrey BF, Chao EYS: Fracture of the porous-coated metal tray of a biologically fixed knee prosthesis. Clin Orthop 228:182, 1988 4. Altintas F, Sener N, Ugutmen E: Fracture of the tibial tray after total knee arthroplasty. J Arthroplasty 14: 112, 1999 5. Miller EH, Shastri R, Shih CI: Fracture failure of a forged Vitallium prosthesis. J Bone Joint Surg Am 64:1359, 1982 6. Ahir SP, Blunn GW, Haider H, et al: Evaluation of a testing method for the fatigue performance of total knee tibial trays. J Biomechanics 32:1049, 1999 7. Maruyama M, Terayama K, Sunohara H, et al: Fracture of the tibial tray following PCA knee replacement. Arch Orthop Trauma Surg 113:330, 1994 8. Hood RW, Wright TM, Burstein AH: Retrieval anal-
802 The Journal of Arthroplasty Vol. 19 No. 6 September 2004
9.
10. 11.
12.
13.
14. 15.
16.
ysis of total knee prostheses: a method and its application to 48 total condylar prostheses. J Biomed Mater Res 17:829, 1983 Bloebaum RD, Nelson K, Dorr LD, et al: Investigation of early surface delamination observed in retrieved hear-pressed tibial inserts. Clin Orthop 269:120, 1991 Flivik G, Ljung P, Rydholm U: Fracture of the tibial tray of the PCA knee. Acta Orthop Scand 61:26, 1990 Fradisar IA, Hoffmann ML, Askew MJ: Fracture of a fenestrated metal backing of a tibial knee component. J Arthroplasty 4:27, 1989 Collier JP, Mayor MB, McNamara JL, et al: Analysis of the failure of 122 polyethylene inserts from uncemented tibial knee components. Clin Orthop 273: 232, 1991 Harrington IJ: Static and dynamic loading patterns in knee joints with deformities. J Bone Joint Surg Am 65:247, 1983 Cameron HU: Tibial component wear in total knee replacement. Clin Orthop 309:29, 1994 Lewis P, Rorabeck CH, Bourne RB, et al: Posteromedial tibial polyethylene failure in total knee replacements. Clin Orthop 299:11, 1994 Wasielewski RC, Galante JO, Leighty RM, et al: Wear patterns on retrieved polyethylene tibial inserts and
17.
18.
19.
20.
21.
22.
23.
their relationship to technical considerations during total knee arthroplasty. Clin Orthop 299:31, 1994 Blunn GW, Joshi AB, Minns RJ, et al: Wear in retrieved condylar knee arthroplasties. J Arthroplasty 12:281, 1997 Jacobs JJ, Latanision RM, Rose RM, et al: The effect of porous coating processing on the corrosion behavior of cast Co-Cr-Mo surgical implant alloys. J Orthop Res 8:874, 1990 Pilliar RM: Powder metal made orthopedic implants with porous surface for fixation by tissue ingrowth. Clin Orthop 176:42, 1983 Ranawat CS, Johanson NA, Rimnac CM, et al: Retrieval analysis of porous-coated components for total knee arthroplasty. Clin Orthop 209:244, 1986 Gruen TA, McNeice GM, Amstutz HC: “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop 141:17, 1979 Norton MR, Eyres KS: Irrigation and suction technique to ensuer reliable cement penetration for total knee arthroplasty. J Arthroplasty 15:468, 2000 Bartel DL, Bicknell VL, Wright VA: The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement. J Bone Joint Surg Am 68:1041, 1986