Influence of time in-situ and implant type on fixation strength of cemented tibial trays — A post mortem retrieval analysis
Introduction
The most common treatment for a diseased knee joint is replacement by total knee arthroplasty (TKA). National revision rates of less than 5% at 10 years (Swedish Knee Register, 2010), in combination with relief from discomfort and relatively low cost, make this surgical procedure one of the most successful (Lavernia et al., 1997). However, absolute numbers of global implantations are around one million annually and are steadily increasing, and the corresponding absolute number of revisions amounts to thousands (Kurtz et al., 2007).
Currently, the majority of TKAs is cemented and in national registries a quarter to a third of primary TKA revisions are attributed to loosening of the cemented tibial component (Australian Hip and Knee Register, 2010, Kurtz et al., 2010, National Joint Registry for England and Wales, 2010, Swedish Knee Register, 2010). Cementing technique, as well as bone quality, have been related to implant loosening (Guha et al., 2008, Minoda et al., 2010, Rea et al., 2007, Swedish Knee Register, 2010). In various studies the depth of penetration of the cement into the cancellous bone has been shown to increase the strength of the bone–cement interface, leading to improved implant anchorage (Askew and Lewis, 1981, MacDonald et al., 1993, Schlegel et al., 2010). However, there is little documentation relating the long-term clinical status of the cement mantle to cement penetration. Neither is it clear whether the bone–cement or the implant–cement interface becomes the weaker link.
Polyethylene (PE) insert wear has been identified to be an indication for revision in about 10% of the clinical cases (Hossain et al., 2010, Lu et al., 2010, Swedish Knee Register, 2010). Little is known about the clinical relationship between PE insert damage and implant stability over time in situ for different implant designs. Material properties of tibial inserts have been related to clinical performance, but other factors such as surgical technique, sterilisation method, ligament tension and patient-specific variables in particular, also play an important role (Collier et al., 1991, Collier et al., 2006, Collier et al., 2007, Collier et al., 2008, Edidin et al., 2000, Kurtz et al., 2000).
The purpose of this study was to assess the mechanical stability of tibial trays that had been in service in vivo. This was undertaken by measuring the anchorage capacity of post-mortem retrieved tibial trays and relating it to the failure mode, implant design, cement penetration, bone quality and wear of the polyethylene liner. We expected anchorage capacity to decrease with time, with less cement penetration, with lower bone density and higher polyethylene wear.
Section snippets
Specimens
Twenty-two knees implanted with TKAs were retrieved serially over a period of 6 months from 17 donors post mortem at the Department of Legal Medicine at the University Clinic in Hamburg. Consent of the relatives was given, as well as ethical approval from the Medical Association of the State of Hamburg. All joints had been functioning asymptomatically, although a detailed description of activity was not available. Each tibia was sectioned approximately 15 cm distally to the knee joint, excised,
Specimens
Of the 22 retrievals, 12 patients had unilateral TKA, and 5 bilateral TKA. 16 of the implants were from female donors and 6 from male donors. The mean donor age per implant at the time of death was 80.1 years (68.8–98.3 years). The mean BMI per implant retrieved was 30.5 kg/m2 (19.6–43.0 kg/m2). Specimens were retrieved after a mean of 5.3 years in situ (0.0–11.2 years). The majority (n = 15) of implants was of fixed bearing design (Table 1). Nine of these were titanium, and 6 cobalt-chrome (CoCr). The
Discussion
The aim of this study was to better understand the mechanical failure of total knee replacements. For this purpose randomly retrieved post-mortem specimens were available, which had been in situ over periods of 0 to 11.2 years. A general decrease in anchorage strength with time in situ was observed for all implants combined and also within the PFC implant subgroups, despite variations in failure modes (failure interface). Expected effects, such as increased polyethylene wear score with time in
Conclusion
Autopsy retrieval studies allow implant systems to be studied that have been in service in vivo. In this relatively large knee retrieval study an even distribution of the input variables for a random sample allowed observations that give insight into tibial component anchorage. In contrast to a group of mixed retrieved implants, two popular contemporary bearing designs demonstrated minimal polyethylene delamination and pull-out failure was predominantly at the stem–cement interface,
Acknowledgements
This study was funded by a grant from The State of Hamburg, Germany.
References (42)
- et al.
Hip contact forces and gait patterns from routine activities
J. Biomech.
(2001) - et al.
Risk factors for onset of osteoarthritis of the knee in older adults: a systematic review and meta-analysis
Osteoarthritis Cartilage
(2010) - et al.
Patient, implant, and alignment factors associated with revision of medial compartment unicondylar arthroplasty
J. Arthroplasty
(2006) - et al.
Midterm results with the PFC Sigma total knee arthroplasty system
J. Arthroplasty
(2008) - et al.
Degradation of mechanical behavior in UHMWPE after natural and accelerated aging
Biomaterials
(2000) - et al.
The relationship between the clinical performance and large deformation mechanical behavior of retrieved UHMWPE tibial inserts
Biomaterials
(2000) - et al.
Reasons for revision of first-generation highly cross-linked polyethylenes
J. Arthroplasty
(2010) - et al.
A new approach to quantify trabecular resorption adjacent to cemented knee arthroplasty
J. Biomech.
(2012) - et al.
An experimental study of damage accumulation in cemented hip prostheses
Clin. Biomech.
(1996) - et al.
Comparison of single-photon and dual-energy X-ray absorptiometry of the radius
Bone Miner.
(1992)
Analysis of model variables and fixation post length effects on stresses around a prosthesis in the proximal tibia
J. Biomech. Eng.
Annual report
The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement
J. Bone Joint Surg. Am.
The effect of surface preparation on metal/bone cement interfacial strength
J. Biomed. Mater. Res.
Analysis of the failure of 122 polyethylene inserts from uncemented tibial knee components
Clin. Orthop. Relat. Res.
Factors associated with the loss of thickness of polyethylene tibial bearings after knee arthroplasty
J. Bone Joint Surg. Am.
Radiographic assessment of the thickness lost from polyethylene tibial inserts that had been sterilized differently
J. Bone Joint Surg. Am.
Midterm survival of a contemporary modular total knee replacement: a multicentre study of 1970 knees
J. Bone Joint Surg. Br.
Polyethylene wear of metal-backed tibial components in total and unicompartmental knee prostheses
J. Bone Joint Surg. Br.
Tensile fatigue failure of acrylic bone cement
J. Biomech. Eng.
Radiolucent lines below the tibial component of a total knee replacement (TKR) — a comparison between single-and two-stage cementation techniques
Int. Orthop.
Cited by (45)
Endurance Behavior of Cemented Tibial Tray Fixation Under Anterior Shear and Internal-External Torsional Shear Testing: A New Methodological Approach
2022, Journal of ArthroplastyCitation Excerpt :These results are on a comparable level as the previously performed quasi-static push-out testing on AS VEGA System tibial baseplates in an initial fixation stage after implantation with 2,705 N ± 515 N, demonstrating the preservation of a high implant-cement-bone interface bonding even after severe high-cycle fatigue shear testing [32]. In a postmortem tibia retrieval analysis on various designs, Gebert de Uhlenbrock et al [37] analyzed the influence of the time in situ on the fixation strength with pull-out forces ranging from 2,751 N after only 2 days to 231 N after 9 years in service, with a mean time in situ of 5.3 years (range 0-11 years) for the cohort. Schlegel et al [29] performed a similar pull-out test on proximal human donor tibiae to determine the fixation strength of PFC Sigma FB trays, a clinically long-term successful implant based on a meta-analysis on 241,632 primary knee arthroplasties by Hopley and Dalury [6].
Effect of bone density and cement morphology on biomechanical stability of tibial unicompartmental knee arthroplasty
2020, KneeCitation Excerpt :However, they do not address biological changes that occur at the interface with in vivo use. As recent studies on post mortem human cadavers have documented a loss of interlock at the cement–bone interface by resorption of bone mass over time, slightly higher penetrations might be needed for long-term survival [18,19]. This justifies further attempts to improve the cement–bone interface.