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Delayed failure of meniscal bearing elements in total knee arthroplasty
The Journal of Arthroplasty Vol. 11 No. 5 1996
Case Report
Delayed Failure of Meniscal Bearing Elements in Total Knee Arthroplasty Jack M. Bert, MD
Abstract: Dislocation and early fracture of meniscal bearing elements have been
reported after New Jersey low-contact-stress (DePuy, Warsaw, IN) total knee arthroplasty. Delayed wear and subsequent failure of meniscal bearing elements in two cases, 8 and 9 years after surgery, are reported. Key words: dislocation, fracture, meniscal bearing elements, failure.
and subsequent failure of meniscal bearing elements at 8 and 9 years, respectively, in otherwise asymptomatic TICAs. The first patient is a 72-year-old m a n w h o had an LCS TKA at age 62. This patient did e x t r e m e l y well, with a Hospital for Special Surgery score of 98 for 8.5 years after surgery. The patient complained of progressive pain for 6 m o n t h s prior to his 9-year checkup. He literally n o t e d a grinding sensation w h e n he p r e s e n t e d to the office, and his radiographs s h o w e d complete collapse of the femoral c o m p o n e n t onto the tibial base plate (Fig. 1). At the time of revision, the meniscal bearings illustrated significant wear and delamination with three additional small fragments of p o l y e t h y l e n e e n t r a p p e d in the joint (Fig. 2). The second case involved a 76-year-old w o m a n w h o had an LCS TKA at age 68. She was asymptomatic for 8 years, and her radiographs, as well as clinical examination, were identical to those for case 1. Similar findings ol both meniscal bearing elements were n o t e d at the time of revision surgery. In the first case, because of m a r k e d scoring of the femoral condylar weight-bearing surface, we elected to revise the femoral c o m p o n e n t . In the second case, there was only trace scoring of the femoral c o m p o n e n t , and we elected simply to
In the middle to late 1970s, Goodfellow and O'Connor designed a prosthesis with removable polyethylene bearings on tibial tracks in an attempt to decrease contact stresses at the femoral-tibial bearing interface. These mobile bearings theoretically should eliminate torque loads and allow axial rotation as well as anteror posterior translation, resulting in a decrease in bearing contact stresses as well as lower constraint forces [1]. The New Jersey low-contact-stress (LCS, DePuy, Warsaw, IN) meniscal bearing total knee arthroplasty (TKA) system was developed in the 1970s; it was essentially a modified Oxford TKA (Nuffield Orthopaedic Center, Oxford, UK) having the same advantages of an assodated increase in flexion allowed by the mobile elements and the improvem e n t of variable femoral curvature articulation. Developers of designs with mobile elements argue that the chances for long-term implant performance and fixation are improved by decreasing implant contact stresses [2,3]; however, two studies have recently reported difficulties with early breakage of the mobile bearing elements as well as dislocation/ subluxation [4,5]. This study reports delayed wear From Landmark Orthopedics, St. Paul, Minnesota. Reprint requests: Jack M. Bert, MD, Landmark Orthopedics, 17 West Exchange Street, Suite 307, St. Paul, MN 55102.
611
612
The Journal of Arthroplasty Vol. 11 No. 5 August 1996
Fig. 2. Wear and delamination of meniscal bearing elements.
eral tibial r u n n e r has b e e n r e p o r t e d [5]. The t w o cases of bearing failure r e p o r t e d h e r e m a y be related to the quality of the p o l y e t h y l e n e used in the original bearings of this s y s t e m or simply to increased contact stresses, w h i c h m a y not be dissipated by the design of this system. These two cases a p p e a r to be the first published delayed failures of meniscal bearing elements due to wear. Fig. I. Collapse of joint space with subluxation of components.
References
replace the bearing e l e m e n t s w i t h n e w meniscal bearings, w h i c h did allow for v e r y rapid rehabilitation of this patient. The patients w e r e discharged f r o m the hospital in 4.5 a n d 3.5 days, respectively. Theoretically, pressures t r a n s f e r r e d to the p o l y e t h y l e n e surface are m u c h less w i t h a m e n i s cal bearing s y s t e m a n d m o r e e v e n l y distributed w h e n full surface contact as c o m p a r e d w i t h a p o i n t or line contact using o t h e r systems is perm i t t e d [2]. This meniscal bearing e l e m e n t s y s t e m should potentially offer a r e d u c t i o n in b o t h m a j o r l o n g - t e r m p r o b l e m s in TKA loosening a n d w e a r [3]; h o w e v e r , bearing failure as a result of e n t r a p m e n t of a s u b l u x e d lateral bearing b e t w e e n the f e m o r a l c o m p o n e n t a n d posterior edge of the lat-
1. Goodfellow JW, O'Connor J J: Clinical results of the Oxford knee: surface arthroplasty of the tibiofemoral joint with a meniscal bearing prosthesis. Orthop 205: 21, 1986 2. Buechel FF, Pappas MJ: The New Jersey low contact stress knee replacement system: biomechanial rationale and review, the first 123 cemented cases. Arch Orthop Trauma Surg 105:197, 1986 3. Buechel FE Pappas MJ: The New Jersey LCS knee replacement system, biomechanical rationale. Contemp Orthop 14:52, 1987 4. Bert JM: Dislocation subluxation of meniscal bearing elements after New Jersey low contact stress total knee arthroplasty. Clin Orthop 254:211, 1990 5. Weaver JK, Derkash RS, Greenwald SA: Difficulties with bearing disclocation and breakage using a movable bearing total knee replacement system. Clin Ortho p 290:244, 1993
Case Report
Delayed Failure of Meniscal Bearing Elements in Total Knee Arthroplasty Jack M. Bert, MD
Abstract: Dislocation and early fracture of meniscal bearing elements have been
reported after New Jersey low-contact-stress (DePuy, Warsaw, IN) total knee arthroplasty. Delayed wear and subsequent failure of meniscal bearing elements in two cases, 8 and 9 years after surgery, are reported. Key words: dislocation, fracture, meniscal bearing elements, failure.
and subsequent failure of meniscal bearing elements at 8 and 9 years, respectively, in otherwise asymptomatic TICAs. The first patient is a 72-year-old m a n w h o had an LCS TKA at age 62. This patient did e x t r e m e l y well, with a Hospital for Special Surgery score of 98 for 8.5 years after surgery. The patient complained of progressive pain for 6 m o n t h s prior to his 9-year checkup. He literally n o t e d a grinding sensation w h e n he p r e s e n t e d to the office, and his radiographs s h o w e d complete collapse of the femoral c o m p o n e n t onto the tibial base plate (Fig. 1). At the time of revision, the meniscal bearings illustrated significant wear and delamination with three additional small fragments of p o l y e t h y l e n e e n t r a p p e d in the joint (Fig. 2). The second case involved a 76-year-old w o m a n w h o had an LCS TKA at age 68. She was asymptomatic for 8 years, and her radiographs, as well as clinical examination, were identical to those for case 1. Similar findings ol both meniscal bearing elements were n o t e d at the time of revision surgery. In the first case, because of m a r k e d scoring of the femoral condylar weight-bearing surface, we elected to revise the femoral c o m p o n e n t . In the second case, there was only trace scoring of the femoral c o m p o n e n t , and we elected simply to
In the middle to late 1970s, Goodfellow and O'Connor designed a prosthesis with removable polyethylene bearings on tibial tracks in an attempt to decrease contact stresses at the femoral-tibial bearing interface. These mobile bearings theoretically should eliminate torque loads and allow axial rotation as well as anteror posterior translation, resulting in a decrease in bearing contact stresses as well as lower constraint forces [1]. The New Jersey low-contact-stress (LCS, DePuy, Warsaw, IN) meniscal bearing total knee arthroplasty (TKA) system was developed in the 1970s; it was essentially a modified Oxford TKA (Nuffield Orthopaedic Center, Oxford, UK) having the same advantages of an assodated increase in flexion allowed by the mobile elements and the improvem e n t of variable femoral curvature articulation. Developers of designs with mobile elements argue that the chances for long-term implant performance and fixation are improved by decreasing implant contact stresses [2,3]; however, two studies have recently reported difficulties with early breakage of the mobile bearing elements as well as dislocation/ subluxation [4,5]. This study reports delayed wear From Landmark Orthopedics, St. Paul, Minnesota. Reprint requests: Jack M. Bert, MD, Landmark Orthopedics, 17 West Exchange Street, Suite 307, St. Paul, MN 55102.
611
612
The Journal of Arthroplasty Vol. 11 No. 5 August 1996
Fig. 2. Wear and delamination of meniscal bearing elements.
eral tibial r u n n e r has b e e n r e p o r t e d [5]. The t w o cases of bearing failure r e p o r t e d h e r e m a y be related to the quality of the p o l y e t h y l e n e used in the original bearings of this s y s t e m or simply to increased contact stresses, w h i c h m a y not be dissipated by the design of this system. These two cases a p p e a r to be the first published delayed failures of meniscal bearing elements due to wear. Fig. I. Collapse of joint space with subluxation of components.
References
replace the bearing e l e m e n t s w i t h n e w meniscal bearings, w h i c h did allow for v e r y rapid rehabilitation of this patient. The patients w e r e discharged f r o m the hospital in 4.5 a n d 3.5 days, respectively. Theoretically, pressures t r a n s f e r r e d to the p o l y e t h y l e n e surface are m u c h less w i t h a m e n i s cal bearing s y s t e m a n d m o r e e v e n l y distributed w h e n full surface contact as c o m p a r e d w i t h a p o i n t or line contact using o t h e r systems is perm i t t e d [2]. This meniscal bearing e l e m e n t s y s t e m should potentially offer a r e d u c t i o n in b o t h m a j o r l o n g - t e r m p r o b l e m s in TKA loosening a n d w e a r [3]; h o w e v e r , bearing failure as a result of e n t r a p m e n t of a s u b l u x e d lateral bearing b e t w e e n the f e m o r a l c o m p o n e n t a n d posterior edge of the lat-
1. Goodfellow JW, O'Connor J J: Clinical results of the Oxford knee: surface arthroplasty of the tibiofemoral joint with a meniscal bearing prosthesis. Orthop 205: 21, 1986 2. Buechel FF, Pappas MJ: The New Jersey low contact stress knee replacement system: biomechanial rationale and review, the first 123 cemented cases. Arch Orthop Trauma Surg 105:197, 1986 3. Buechel FE Pappas MJ: The New Jersey LCS knee replacement system, biomechanical rationale. Contemp Orthop 14:52, 1987 4. Bert JM: Dislocation subluxation of meniscal bearing elements after New Jersey low contact stress total knee arthroplasty. Clin Orthop 254:211, 1990 5. Weaver JK, Derkash RS, Greenwald SA: Difficulties with bearing disclocation and breakage using a movable bearing total knee replacement system. Clin Ortho p 290:244, 1993