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      Can Achilles tendon be used as a new distal landmark for coronal tibial component alignment in total knee replacement surgery? An observational MRI study

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          Abstract

          Background

          In total knee arthroplasty, it is better to use more than one reference point for correct alignment of the components. By measuring the distances of Achilles tendon (AT) and other conventional landmarks from the mechanical axis in magnetic resonance imaging (MRI) of the ankle, we aimed to demonstrate that, as a novel landmark which can help for correct alignment in the coronal plane, AT is a better option than other landmarks.

          Materials and methods

          This retrospective study was done on 53 ankle MRIs that met the criteria for inclusion to the study among 158 ankle MRIs. After identification of the mechanical axis, the distances of distal landmarks, which were extensor hallucis longus tendon (EHLT), tibialis anterior tendon (TAT), dorsalis pedis artery (DPA), AT, extensor digitorum longus tendon (EDLT), and malleoli, were measured from the mechanical axis and were statistically evaluated.

          Results

          In proximal measurements, the distances of the landmarks to the mechanical axis (on average) were AT, 2.64±1.62 mm lateral; EHLT, 3.89±2.45 mm medial; DPA, 4.69±2.39 mm medial; TAT, 8.24±3.60 mm medial; and EDLT, 14.2±4.14 mm lateral ( P<0.001). In distal measurements, the distances of the landmarks to the mechanical axis (on average) were AT, 1.99±1.24 mm medial; EHLT, 4.27±2.49 mm medial; DPA, 4.79±2.10 mm medial; TAT, 12.9±4.07 mm medial; and EDLT, 12.18±4.17 mm lateral ( P<0.001).

          Conclusion

          In this study, the mechanical axis line, which is the center of talus, passes through the AT. Our MRI investigations showed that the AT, EHLT, DPA, and malleolar center (3–5 mm medial) may help in correct alignment.

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          Most cited references 19

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          Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements.

          One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers. Clinical and radiographic data were reviewed retrospectively to determine the fifteen-year Kaplan-Meier survival rate following 398 primary total knee arthroplasties performed with cement in 280 patients from 1985 to 1990. Preoperatively, most knees were in varus mechanical alignment (mean and standard deviation, 6° ± 8.8° of varus [range, 30° of varus to 22° of valgus]), whereas postoperatively most knees were corrected to neutral (mean and standard deviation, 0° ± 2.8° [range, 8° of varus to 9° of valgus]). Postoperatively, we defined a mechanically aligned group of 292 knees (with a mechanical axis of 0° ± 3°) and an outlier group of 106 knees (with a mechanical axis of beyond 0° ± 3°). At the time of the latest follow-up, forty-five (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with fourteen (13%) of the 106 implants in the outlier group (p = 0.88); twenty-seven (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with eight (7.5%) of the 106 implants in the outlier group (p = 0.88); and seventeen (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with four (3.8%) of the 106 implants in the outlier group (p = 0.49). A postoperative mechanical axis of 0° ± 3° did not improve the fifteen-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.
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            Tibiofemoral alignment and the results of knee replacement.

            We examine the hypothesis that a knee replacement is most likely to survive successfully if it is stable with a coronal tibiofemoral angle close to 7 degrees of valgus, the accepted normal. The records of 428 knee replacements followed up for one to nine years were analysed. The highest success rate was indeed found in those so aligned at operation and such knees were most likely to remain stable. Nevertheless, half of the failures occurred in knees correctly aligned at operation and two-fifths in knees which had remained stable in this alignment; many failures must have been caused by factors other than malalignment. Some knees, well aligned at operation, deteriorated into severely varus or valgus positions; their failure rate was significantly higher than that for knees which remained normally aligned and higher also than for knees severely varus or valgus from operation onwards. Malalignment, in itself, may not be the most important cause of failure, though it probably does compound failure from other causes.
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              • Article: not found

              Intramedullary versus extramedullary tibial alignment systems in total knee arthroplasty.

              One hundred twenty consecutive total knee arthroplasties were performed to compare the accuracy of intramedullary versus extramedullary tibial resection guides. An intramedullary guide (group 1) was used in 60 cases and an extramedullary guide (group 2) was used in another 60 cases. In group 2, the distal portion of the extramedullary guide was shifted 3 mm medial to the midpoint of the ankle in order to position it over the center of the talus. Postoperative tibial component alignment angles were similar in both groups (group 1, 0.43 degrees varus; group 2, 0.36 degrees valgus). However, 88% of tibial components in group 2 were aligned within 2 degrees of the 90 degrees goal versus only 72% of tibial components in group 1. Satisfactory alignment can be obtained with either intramedullary or extramedullary resection guides, although a wider range of error was encountered with intramedullary guide use. Distal positioning of the extramedullary guide over the center of the talus rather than the midpoint of the ankle is important to avoid varus tibial resection. Extramedullary guides avoid the potential complications of intramedullary guide use, including fat embolization and hypoxia, intraoperative fracture, loss of polymethyl methacrylate pressurization, and inability of intramedullary rod passage due to deformity, retained hardware, or pathologic bone disease.
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                Author and article information

                Journal
                Ther Clin Risk Manag
                Ther Clin Risk Manag
                Therapeutics and Clinical Risk Management
                Therapeutics and Clinical Risk Management
                Dove Medical Press
                1176-6336
                1178-203X
                2017
                16 January 2017
                : 13
                : 81-86
                Affiliations
                [1 ]Department of Orthopaedics and Traumatology
                [2 ]Department of Radiology, Faculty of Medicine, Kırıkkale University, Kırıkkale, Turkey
                Author notes
                Correspondence: Sancar Serbest, Department of Orthopaedics and Traumatology, Faculty of Medicine, Kırıkkale University, Ankara Yolu 7. Km, Yahşihan, Kırıkkale 71450, Turkey, Tel +90 533 554 5080, Fax +90 318 225 2819, Email dr.sancarserbest@ 123456hotmail.com
                Article
                tcrm-13-081
                10.2147/TCRM.S125551
                5248942
                © 2017 Tiftikçi et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

                Categories
                Original Research

                Medicine

                achilles tendon, mri, landmark, distal references, alignment, tibial component, total knee arthroplasty

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