title: Potential risk of excising the femoral insertion of the popliteus tendon during primary total knee arthroplasty: a biometric study.
abstract: BACKGROUND
  During total knee arthroplasty (TKA), excision of the popliteus tendon leads to extensive static gaps and reduced mobility. The purpose of this study was to determine the positional relationship between the femoral insertion of the popliteus tendon and the bone cutting lines of various TKA systems.
  
  
  METHODS
  This study included 21 cadaveric right femurs presenting no macroscopic deformity. The lateral image of the femur and the template of the femoral component were overlaid to determine the preservation/excision of the popliteus tendon insertion. TKA systems used were Genesis II, NexGen, low contact stress (LCS), PFC Σ, Scorpio, and Vanguard. The knees in which the insertion was preserved in all implants or excised in at least one implant were classified into intact or the high-risk groups, respectively.
  
  
  RESULTS
  The popliteus tendon was preserved in all specimens with the LCS system. In contrast, the popliteus tendon insertion was excised in ≥1/3 of the specimens with the other systems. The anteroposterior diameter was significantly larger in the intact group than that in the high-risk group (58.1 ± 4.5 mm vs. 53.7 ± 2.7 mm; p = 0.018). The high-risk group included more knees from female cadavers than the intact group (70 vs. 9 %; p = 0.008).
  
  
  CONCLUSIONS
  During primary TKA, the femoral insertion of the popliteus tendon could be inevitably excised, regardless of technical problems. We demonstrate that the unique design of the LCS system preserves the popliteus tendon insertion. In addition, small knees and females may be risk factors for excision of the insertion.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan. a-takahashi@med.tohoku.ac.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Tohoku Orthopaedic Clinic, 4-9-30 Kamiyagari, Izumiku-Ku, Sendai, Miyagi, 981-3121, Japan.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Sugita
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
authors.forename: Toshimi
authors.initials: T
authors.lastname: Aizawa
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Chiba
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kamimura
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Aki
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000601:surgery; D006801:Humans; D007593:Joint Instability / Q000517:prevention & control*; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013710:Tendons / Q000033:anatomy & histology / Q000601:surgery*