Retrieval analysis in total knee arthroplasty

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.