BACKGROUND: In this study, the traditional \"Anatomical Landmark-Distance Method (AL-DM)\" in the formation of joint line (JL) was compared with \"Adductor Tubercle-Ratios method\" (AT-RM), and the effect of reestablishment of JL on clinical and functional outcomes were evaluated.
METHODS: 16 revision total knee arthroplasties (rTKAs) were performed by using \"AT-RM\" (group 1) and 16 rTKA by using \"AL-DM\" (group 2) in our clinic between 2015 and 2018. The data were prospectively collected and a total of 32 knees of 31 patients were analyzed. At the final follow-up, knee functions were evaluated by using Knee Society Score (KSS) knee and function, Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, Short Form-36 (SF-36) questionnaires and physical examinations.
RESULTS: Postoperative flexion arc was higher in Group 1. KSS knee and function scores were better in group 1. In group1, JL was reestablished successfully in all revision rTKAs in terms of ATJL and the tibial tubercle TT-JL ratios. The improvement in KSS knee and function scores and WOMAC scores were also better in group 1. Measurements showed that the improvement in KSS scores increased as AT-JL and TT-JL distances approached the calculated values.
CONCLUSIONS: \"AT-RM\" was shown to be superior to the traditional distance method in terms of JL reestablishment. Functional results and patient satisfaction increased when JL was reestablished.

Joint line (JL) restoration is one of the major challenges in revision total knee arthroplasty (rTKA). There is debate regarding the most reliable methodology for the assessment of JL level during revision surgery. Among the strategies, the use of adductor tubercle (AT) as an anatomical landmark has been proposed. The purpose of this paper is to systematically review the available literature to understand the reliability of AT ratio to identify the JL, and the advantages and drawbacks of its application. A research was performed on the PubMed, Embase, Cochrane and Google Scholar databases based on the following inclusion criteria for articles\' selection: (I) clinical reports of any level of evidence, (II) written in the English language, (III) published from 2010 to 2020, (IV) dealing with the use of the adductor tubercle as a landmark to restore JL in revision TKA. All relevant data were extracted by two independent investigators, and discrepancies were resolved by discussion and consensus. A total of 13 studies were included: nine were radiographic evaluations, 3 clinical reports and 1 was an ex-vivo study. Radiographic studies highlighted that AT is a landmark easy to identify, with high intra and inter-observer agreement, irrespective of gender, age and size of the patient. The comparison with other bony landmarks revealed superior reliability in favor of AT. Also during surgical procedures, AT can be safely located and some clinical studies confirmed that AT ratio helps surgeon in re-establishing a correct JL and achieve ligament balancing even in complex revision cases. AT is a reliable and easily detectable landmark, and AT ratio is a valid tool to determine the JL level and help surgeons to restore the JL and simultaneously achieve knee ligament balancing in r-TKA.