Impacted morsellised allografts have successfully been used to address the problem of poor bone stock in revision surgery. However, concern exists about pathogen transmission, high cost and shortage of supply of donor bone. Bone graft extenders, such as tricalciumphosphate (TCP) and hydroxyapatite (HA), have been developed to minimize the use of donor bone. In a human cadaver model we evaluated the surgical and mechanical feasibility of a TCP/HA bone graft extender during impaction grafting revision surgery.TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability as compared to bone graft alone (subsidence ratio graft : TCP/HA = 2.34).If surgeons are properly trained, this type of graft extender can be viable for impaction grafting revision surgery.
Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery. A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed.
Impaction allograft as a scaffold for bone-forming cells is a tissue-engineering approach for filling bone defects that are commonly encountered during revision total joint replacement (THR). The purpose of this in vitro study is to assess the viability of mesenchymal stem cells (MSC) grown on allograft following impaction using forces similar to those measured during revision total hip replacements. Impaction forces of 0, 3, 6, and 9 kN were used representing normal and high impact. The results showed that the viability in the 3 and 6 kN groups was not significantly reduced compared with that of the 0 kN group, while the survival of the MSCs was significantly reduced after 9 kN impaction force. This study suggests that the addition of MSCs to the allograft scaffold will survive normal impaction force in revision THR.
This parallel‐groups study (n = 1,857) investigates compliance of untrained assessors with tetrad instructions. Stimuli are four unique color swatches that differ only in their green chromaticities. Results confirm that the swatches used in this study were generally perceived as nonconfusable visual stimuli ordered A, B, C, D, and that AB and CD were more different than BC. These stimuli thus modeled the scenario in which following the tetrad decision strategy (grouping samples into two groups of two by similarity) gives a correct response, whereas following the select‐two decision strategy (selecting the two most similar samples) gives an incorrect response. Four of the five variants of tetrad task instructions, including the tetrad instructions that are usually recommended, were understood by roughly 90–95% of the assessors. Neither perceptual variance nor guessing provided adequate explanations for the incorrect groupings observed. Results indicate that the optimal cognitive decision strategy is not always followed because some assessors misinterpret instructions systematically. Results imply that d′ estimates from the conventional tetrad test method with untrained assessors may slightly underestimate δ. As a safeguard, it is suggested that any written task instructions be supplemented with verbal instructions and/or visual demonstrations, with the aim of increasing task understanding.
Practical applications
This paper uses empirical evidence from untrained assessors to investigate their performance on various tetrad instructions. Conclusions from this study are relevant to both researchers and practitioners: (i) observed results confirm that the best‐practices tetrad instructions performs well against the other candidate tetrad instructions that were tested; (ii) the use of dissimilar samples revealed that some incorrect tetrad responses are due to task misunderstanding, rather than perceptual variance, as would be assumed by a Thurstonian model; (iii) discriminal distance (d′) estimates from the conventional tetrad test method with untrained assessors may slightly underestimate the true population parameter (δ); and (iv) practitioners are advised to communicate task instructions to untrained assessors using multiple modes (verbal, visual) with the aim of increasing task understanding.
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