Knee Surgery, Sports Traumatology, Arthroscopy
Increased valgus laxity in ﬂexion with greater tibial resection depth
following total knee arthroplasty
· N. White
· R. Gaillard
· L. Cheze
· E. Servien
· P. Neyret
· S. Lustig
Received: 10 December 2017 / Accepted: 15 May 2018
© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018
Purpose Soft tissue balancing is of central importance to outcome following total knee arthroplasty (TKA). However,
there are lack of data analysing the eﬀect of tibial bone cut thickness on valgus laxity. A cadaveric study was undertaken to
assess the biomechanical consequences of tibial resection depth on through range knee joint valgus stability. We aimed to
establish a maximum tibial resection depth, beyond which medial collateral ligament balancing becomes challenging, and
a constrained implant should be considered.
Methods Eleven cadaveric specimens were included for analysis. The biomechanical eﬀects of increasing tibial resection
were studied, with bone cuts made at 6, 10, 14, 18 and 24 mm from the lateral tibial articular surface. A computer naviga-
tion system was used to perform the tibial resection and to measure the valgus laxity resulting from a torque of 10 Nm.
Measurements were taken in four knee positions: 0° or extension, 30°, 60° and 90° of ﬂexion. Intra-observer reliability was
assessed. A minimum sample size of eight cadavers was necessary. Statistical analysis was performed using a nonparametric
Spearman’s ranking correlation matrix at the diﬀerent stages: in extension, at 30°, 60° and 90° of knee ﬂexion. Signiﬁcance
was set at p < 0.05.
Results There was no macroscopic injury to the dMCL or sMCL in any of the specimens during tibial resection. There
was no signiﬁcant correlation found between the degree of valgus laxity and the thickness of the tibial cut with the knee
in extension. There was a statistically signiﬁcant correlation between valgus laxity and the thickness of the tibial cut in all
other knee ﬂexion positions: 30° (p < 0.0001), 60° (p < 0.001) and 90° (p < 0.0001). We identiﬁed greater than 5° of valgus
laxity, at 90° of knee ﬂexion, after a tibial resection of 14 mm.
Conclusion Increased tibial resection depth is associated with signiﬁcantly greater valgus laxity when tested in positions from
30° to 90° of ﬂexion, despite stability in extension. Greater than 5° of laxity was identiﬁed with a tibial resection of 14 mm.
When a tibial bone cut of 14 mm or greater is necessary, as may occur with severe preoperative coronal plane deformity, it
is recommended to consider the use of a constrained knee prosthesis.
Keywords Tibial bone cut · Total knee arthroplasty · Medial collateral ligament · Knee stability · Total knee replacement ·
* S. Lustig
Centre Albert Trillat, Orthopaedic Surgery, Croix-Rousse
Hospital, Lyon, France
Univ Lyon, Université Claude Bernard Lyon 1, IFSTTAR,
LBMC UMR_T9406, 69622 Lyon, France