Retrieval analysis in total knee arthroplasty

Table 1 Metrology tools to investigate the root cause of implant failure

Qualitative methods	Quantitative methods
Visual investigation	Semi-quantitative methods, such as Hood, Goldberg and other visual scoring systems
Microscopic investigation	Gravimetric method
SEM	AFM
EDS	VSI
XRD	Coronal and sagittal plane radiographs
Spectroscopy: AES, XPS, Raman spectroscopy, FTIR	2D-CT
-	3D-CT
-	SPECT

SEM: Scanning electron microscopy; EDS: Energy dispersive X-ray spectroscopy; XRD: X-ray diffractometry; AES: Auger electron spectroscopy; XPS: X-ray photoelectron spectroscopy; FTIR: Fourier transform infrared spectroscopic; AFM: Atomic force microscopy; VSI: Vertical scanning interferometer; 2D-CT: Two-dimensional computed tomography; 3D-CT: Three-dimensional computed tomography; SPECT: Single-photon emission computerized tomography.

Table 2 Studies analyzing the wear of retrieved total knee arthroplasty polyethylene components

Number	Characteristic
1	Visual assessment of wear patterns, CMM
2	Surface laser profilometry
3	Laser scanner CMM
4	PE component thicknesses measurements using a dial indicator
5	Visual assessment of wear patterns, micro-CT
6	Volumetric wear analysis with micro-CT
7	Profilometry with a non-contact profilometer
8	PE component thicknesses measurements
9	Visual assessment of wear patterns, video microscopy, low-incidence laser CMM
10	Visual assessment of wear patterns, linear wear measurement with micro-CT
11	Visual assessment of wear patterns, topographical analysis
12	Laser scanner CMM
13	Raman spectroscopy
14	Calculation of wear based on the reference thickness of PE components with survival

CMM: Coordinate measuring machine; PE: Polyethylene; CT: Computed tomography.

Table 3 Main data on general concepts in retrieval analysis in total knee arthroplasty

Ref.	Methods	Results	Conclusions
Stoner et al[1], 2013	These authors stated that rotating-platform TKA, although purported to have superior kinematics, had shown no clinical advantages over those of fixed-bearing TKA	Rotating-platform and fixed-bearing PE components had similar tibiofemoral damage scores. Besides, no differences were seen in the thicknesses between fixed- and rotating-platform PE components	No damage advantage to the mobile-bearing design was found
Heyse et al[2], 2014	Retrieved OxZr femoral components and corresponding PE components were examined to rule out patterns leading to early failure	Sixteen retrieved TKA were included. The prostheses were in situ for 16.4 months on average. There were no failures directly related to the implant	This study did not show major wear of the PE component in TKA using OxZr femoral components
Howard et al[3], 2014	This study analyzed the fixation for 19 non-revised, postmortem retrieved, femoral components of TKA with time in service ranging from 1 years to 22 years	The average initial interdigitation depth was 0.7 mm, and the average final interdigitation depth was 0.13 mm. Loss of interdigitation was 81%	Minimal fixation seemed necessary for long-term success
Vandekerckhove et al[4], 2015	Seventy-six retrieved PE components were analyzed for the RW, lateral lift-off and implications for future constrained revision surgery according to the coronal plane alignment	The RW significantly affected the coronal plane alignment in TKA However, there was no difference in constrained revision between mild varus and moderate varus aligned TKAs	Progressive wear and lateral lift-off were seen with progressive varus alignment
Arnholt et al[5], 2020	These authors tried to determine the preferred sampling location for tissue analysis in TKA and evaluate metal concentrations, inflammatory cytokines, component damage, and tissue metallosis	Increased Co was associated with decreased TNF-α and IL-1 beta. Increased Cr was associated with decreased TNF-α, IL-6, and MIP-3α	These authors observed elevated Co, Cr and Ti concentrations in tissue from necropsy-retrieved TKA
Perkins et al[6], 2020	These authors measured the laxity patterns of 47 harvested cadaver specimens with primary TKAs in a custom knee-testing machine at full extension and at 30°, 60°, and 90° of flexion. The wear patterns of the tibial inserts were assessed using a semiquantitative method which was a modified approach of that proposed by Hood et al in 1983	Statistical analysis found that the PS TKA cohort had a statistically significant increase in varus laxity at 60° and 90° of flexion, as well as total coronal laxity at 60° of flexion when compared to the posterior CR cohort	Whether a CR or PS TKA is used, surgeons need to avoid the pitfalls that may create greater flexion laxity during the procedure to optimize long-term PE component wear
Bhalekar et al[7], 2021	These authors investigated whether wear and backside deformation of PE components may influence the cement cover of tibial trays of explanted TKAs	The median planicity values of the PE components used with central locking trays were significantly greater than of those with peripheral locking PE components (205 microns vs 85 microns)	Explanted TKAs with central locking mechanisms were significantly more likely to debond from the cement mantle
Hothi et al[8], 2022	Retrieval analysis was performed with a micro-CT method to assess the thickness differences between medial and lateral sides of PE components with symmetrical designs. SPECT/CT was performed prior to revision. Quantitative and qualitative medio-lateral comparisons of BTU intensity and distribution in the tibia were performed	Patients showing a more extended BTU in the medial compartment also had a significantly thinner PE component in the medial compartment, and vice versa in the lateral side	This was the first study comparing BTU distribution patterns and retrieval findings

TKA: Total knee arthroplasty; RW: Ratio of wear; CT: Computed tomography; OxZr: Qxidized zirconium; SPECT: Single photon emission computed tomography; PE: Polyethylene; BTU: Bone tracer uptake; Co: Cobalt; TNF-α: Tumor necrosis factor alpha; IL: Interleukin; Cr: Chromium; MIP-3α: Macrophage inflammatory protein 3 alpha; PS: Posterior-stabilized; CR: Cruciate-retaining; Ti: Titanium.

Table 4 Main data on polyethylene component wear in retrieval analysis in total knee arthroplasty

Ref.	Methods	Results	Conclusions
Heyse et al[9], 2011	These authors analyzed 16 retrieved TKA with an OxZr femoral component. The PE components were also analyzed applying an established scoring system for wear and surface damage	The average wear and damage score for the tibial PE components was 36. The average score in the visual analysis of the OxZr femoral components was 1.3	This study did not show major wear of the PE component in TKA using OxZr femoral components
Holleyman et al et al[10], 2015	These authors investigated the reciprocating interface at the TKA undersurface articulation using profilometry after in vivo service	Four pristine unimplanted components of two different designs (Stryker Kinemax and DePuy PFC) were examined for control purposes. Mean explant baseplate surface roughness was 1.24 μm. Mean explant UHMWPE component undersurface roughness was 1.16 μm	Findings of this study would support the use of a polished tibial tray over an unpolished design in TKA with the goal of reducing PE component wear by means of providing a smoother backside countersurface for the UHMWPE component
Ponzio et al[11], 2018	These authors evaluated the surface damage, the density of crosslinking, and oxidation in retrieved A-XLPE components from TKA and compared the results with a matched cohort of XLPE components	A-XLPE components had higher rates of burnishing and lower rates of pitting and scratching compared with XLPE components	Retrieval analysis of A-XLPE did not reflect a clinically relevant difference in surface damage, density of crosslinking, or oxidation compared with XLPE components at short-term evaluation
Cerquiglini et al[12], 2018	This study correlated highly accurate CT measurements of pre-revision TKA implant position with findings of retrieval analysis post-revision, to understand the clinical relevance of TKA orientation	There was a significant correlation between tibial slope and damage score on PE components as well as a significant correlation between implants’ position in the axial plane and damage score on PE components	A significant correlation between implant position and PE component surface damage was found. These results showed the importance of optimizing component position to minimize PE component damage
Kahlenberg et al[13], 2023	These authors evaluated the PE component and patient characteristics for 33 primary PS, PE components that were revised with fractured posts: UHMWPE vs the XLPE (highly cross-linked PE) component	Total surface damage scores were higher in the UHMWPE component group vs the XLPE component group	Characteristics of PS post fracture differed between XLPE and UHMWPE components, with fractures occurring in the XLPE component with less generalized surface damage, after a shorter LOI, and with SEM evaluation indicative of a more brittle fracture pattern

TKA: Total knee arthroplasty; OxZr: Qxidized zirconium; PE: Polyethylene; A-XLPE: Antioxidant-stabilized highly crosslinked polyethylene; XLPE: Standard remelted highly crosslinked polyethylene; CT: Computed tomography; PS: Posterior stabilized; UHMWPE: Ultra-high-molecular-weight-polyethylene; LOI: Length of implantation; SEM: Scanning electron microscopy.

Table 5 Main data on some specific designs in retrieval analysis in total knee arthroplasty

Ref.	Methods	Results	Conclusions
Cerquiglini et al[14], 2019	These authors examined 12 Ti PFC Sigma implants, eight CoCr PFC Sigma implants, eight cobalt-chromium PFC Sigma RP implants, and 11 Attune implants	There was no evidence of cement attachment on any of the 11 Attune trays examined. There were significant differences between Ti and CoCr PFC Sigma implants and Attune designs	The majority of the earliest PFC Sigma designs showed evidence of cement, while all of the retrieved Attune trays and the majority of the RP PFC trays in this study had no cement attached
Bormann et al[15], 2020	In this study, wear volume and influencing parameters were investigated at 44 retrieved TKAs with MoM couplings	An elevated wear score of two or higher was found in 43% of cases. A tendency for higher wear scores with higher inlay degradation scores was found	The generated wear volume was high
Mathis et al[16], 2021	These authors investigated the in vivo performance of a new design (Persona), by comparing it with its predecessor (NexGen) in retrieval analysis	The Persona tibial tray showed a significantly smoother surface (0.06 μm) compared to the NexGen (0.2 μm)	The bonding of the antioxidant vitamin-E to the PE component chain used in the novel Persona knee system does not reduce in vivo surface damage compared to highly crosslinked PE component without supplemented vitamin-E used in its predecessor knee system NexGen
Malahias et al[17], 2022	This study examined if the use of the Optetrak Logic PS femoral component was associated with early and more extensive aseptic loosening compared with other PS femoral components. Sixteen individuals received the Optetrak Logic PS femoral component (group A), while 11 received other PS femoral components (group B)	A significant difference was found in presence of backside femoral burnishing between group A (15 of 16 patients; 93.8%) and group B (5 of 11 patients; 45.6%)	The earlier failure rate with the Optetrak Logic PS femoral component was of concern

TKA: Total knee arthroplasty; Ti: Titanium; CoCr: Cobalt-chromium; RP: Rotating platform; MoM: Metal-on-metal; PS: Posterior stabilized; PE: Polyethylene.