Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty
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Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty. / Andersen, Mikkel Rathsach; Winther, Nikolaj; Lind, Thomas; Schrøder, Henrik; Flivik, Gunnar; Petersen, Michael Mørk.
In: Acta Orthopaedica, Vol. 87, No. 6, 2016, p. 607-614.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty
AU - Andersen, Mikkel Rathsach
AU - Winther, Nikolaj
AU - Lind, Thomas
AU - Schrøder, Henrik
AU - Flivik, Gunnar
AU - Petersen, Michael Mørk
PY - 2016
Y1 - 2016
N2 - Background and purpose - Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA. Patients and methods - In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs. Results - We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36 mm (p = 0.02) and 0.42 mm (p = 0.02) between groups, with the highest amount of migration (1.0 mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096 mm (p = 0.5), and when comparing MTPM from 3-24 months, the difference between the groups was 0.23 mm (p = 0.07). Interpretation - In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.
AB - Background and purpose - Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA. Patients and methods - In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs. Results - We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36 mm (p = 0.02) and 0.42 mm (p = 0.02) between groups, with the highest amount of migration (1.0 mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096 mm (p = 0.5), and when comparing MTPM from 3-24 months, the difference between the groups was 0.23 mm (p = 0.07). Interpretation - In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.
KW - Aged
KW - Arthroplasty, Replacement, Knee
KW - Bone Cements
KW - Female
KW - Follow-Up Studies
KW - Humans
KW - Knee Prosthesis
KW - Male
KW - Materials Testing
KW - Middle Aged
KW - Polyethylene
KW - Prospective Studies
KW - Prosthesis Design
KW - Prosthesis Failure
KW - Stress, Mechanical
KW - Time Factors
KW - Weight-Bearing
KW - Journal Article
KW - Randomized Controlled Trial
U2 - 10.1080/17453674.2016.1233654
DO - 10.1080/17453674.2016.1233654
M3 - Journal article
C2 - 27649258
VL - 87
SP - 607
EP - 614
JO - Acta Orthopaedica
JF - Acta Orthopaedica
SN - 1745-3674
IS - 6
ER -
ID: 178958313