title: The adductor tubercle: an important landmark to determine the joint line level in revision total knee arthroplasty.
abstract: OBJECTIVE
  The restoration of the physiological femoro-tibial joint line (JL) is important to obtain a good outcome in revision total knee arthroplasty (RTKA). However, its assessment is challenging. The ratio of the distance between the adductor tubercle (AT) JL (ATJL) and the trans-epicondylar femoral width (FW) was proposed as a reliable method. The purpose of this study was to check whether this ratio is a reliable tool to restore the prosthetic JL height in challenging prosthetic revision cases.
  
  
  METHODS
  Twenty-one patients (mean age 65.8 years) were recruited. During surgery, FW was measured and ATJL distance was calculated using 0.53 (SD 0.03) as the ratio. After implant positioning, the obtained ATJL line was measured to verify the accuracy of the surgical procedure. Thirteen patients presented a healthy contralateral knee: a comparative radiograph examination was performed to verify the appropriateness of the restored JL height.
  
  
  RESULTS
  The intra-operatively calculated ATJL was not significantly different with respect to the measured ATJL obtained after prosthetic component implantation. The comparative analysis between the restored JL and the JL of the contralateral not operated knee was also not statistically significant, thus confirming the appropriateness of the restored JL height.
  
  
  CONCLUSIONS
  This study shows that the method which uses an AT to JL distance/FW ratio to determine the JL level, previously applied in primary TKA, is valid when using intra-operatively acquired measurements in RTKA. This is clinically relevant since it represents a reliable tool which helps surgeons to restore the JL level in challenging prosthetic revision cases.
  
  
  METHODS
  Case series, Level IV.
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy. f.iacono@biomec.ior.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Iacono
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Giovanni Francesco
authors.initials: GF
authors.lastname: Raspugli
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Filardo
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Bruni
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zaffagnini
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Bignozzi
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Mirco
authors.initials: M
authors.lastname: Lo Presti
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Akkawi
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Neri
authors.affiliation: 2nd Orthopaedics and Traumatologic Clinic, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136, Bologna, Italy.|Biomechanics and Technologic Innovation Laboratory and Nanobiotechnology Laboratory, Codivilla-Putti Research Center, Bologna University, Via di Barbiano 1/10, 40136, Bologna, Italy.
authors.forename: Maurilio
authors.initials: M
authors.lastname: Marcacci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005269:Femur / Q000033:anatomy & histology*; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012086:Reoperation / Q000379:methods*
keywords: Adductor tubercle; Femoral width; Joint line; Knee surgery; Ratio; Revision total knee arthroplasty