title: The medial border of the tibial tuberosity as an auxiliary tool for tibial component rotational alignment during total knee arthroplasty (TKA).
abstract: OBJECTIVE
  The objective of this study was to quantify the amount of ensuing internal rotation of the tibial component when positioned along the medial border of the tibial tubercle, thus establishing a reproducible intraoperative reference for tibial component rotational alignment during total knee arthroplasty (TKA).
  
  
  METHODS
  The angle formed from the tibial geometric centre to the intersection of both lines from the middle of the tibial tuberosity and its medial border was measured in 50 patients. The geometric centre was determined on an axial CT slice at 10 mm below the lateral tibial plateau and transposed to a slice at the level of the most prominent part of the tibial tuberosity. Similar measurements were taken in 25 patients after TKA, in order to simulate the intraoperative appearance of the tibia after making its proximal resection.
  
  
  RESULTS
  This angle was found to be similar (n.s.) in normal and post-TKA tibiae [median 20.4° (range 15°-24°) vs. 20.7° (range 16°-25°), respectively]. In 89.3 % of the patients, the angle ranged from 17° to 24°. No statistical difference (p n.s.) was found between women and men in both normal [median -20.7° (range 16°-25°) vs. 19.9° (range 15°-24°)] and post-TKA tibiae [median 21.4° (range 19°-24°) vs. 20° (range 16°-25°)].
  
  
  CONCLUSIONS
  This study found that in 90 % of the patients, the medial border of the tibial tuberosity is internally rotated 17°-24° in relation to the line connecting the middle of the tuberosity to the tibial geometric centre. Since this anatomical landmark may be more easily identifiable intraoperatively than the commonly used "medial 1/3", it can provide a better quantitative reference point and help surgeons achieve a more accurate tibial implant rotational position.
  
  
  METHODS
  Cohort and case control studies, Level III.
authors.affiliation: Tel-Aviv Sourasky Medical Center, Tel Aviv University, Waitzman 6 St, 6423906, Tel Aviv, Israel. mt.drexler@gmail.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Drexler
authors.affiliation: Mount Sinai Hospital, 600 University Avenue, Toronto, ON, M5G 1X5, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Backstein
authors.affiliation: Mount Sinai Hospital, 600 University Avenue, Toronto, ON, M5G 1X5, Canada.
authors.forename: Ueli
authors.initials: U
authors.lastname: Studler
authors.affiliation: Mount Sinai Hospital, 600 University Avenue, Toronto, ON, M5G 1X5, Canada.
authors.forename: Dror
authors.initials: D
authors.lastname: Lakstein
authors.affiliation: Hasharon Campus, Rabin Medical Center Hospital, Derech Ze'ev Jabotinsky 39, 4941492, Petah Tikva, Israel.
authors.forename: Barak
authors.initials: B
authors.lastname: Haviv
authors.affiliation: Department of Orthopaedics, NYU Langone Medical Center Hospital for Joint Diseases, New York, NY, 10003, USA.
authors.forename: Ran
authors.initials: R
authors.lastname: Schwarzkopf
authors.affiliation: Tel-Aviv Sourasky Medical Center, Tel Aviv University, Waitzman 6 St, 6423906, Tel Aviv, Israel.
authors.forename: Tal Frenkel
authors.initials: TF
authors.lastname: Rutenberg
authors.affiliation: Tel-Aviv Sourasky Medical Center, Tel Aviv University, Waitzman 6 St, 6423906, Tel Aviv, Israel.
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Warschawski
authors.affiliation: Tel-Aviv Sourasky Medical Center, Tel Aviv University, Waitzman 6 St, 6423906, Tel Aviv, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Rath
authors.affiliation: Mount Sinai Hospital, 600 University Avenue, Toronto, ON, M5G 1X5, Canada.
authors.forename: Yona
authors.initials: Y
authors.lastname: Kosashvili
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D012399:Rotation; D013977:Tibia / Q000601:surgery*
keywords: Internal rotation angle; Reference point; Tibial component; Total knee arthroplasty