Intraoperative load-sensing drives the level of constraint in primary total knee arthroplasty: Surgical technique and review of the literature

Abstract

Total knee arthroplasty is a traditional surgical procedure aimed to restore function and relief pain in patients with severe knee osteoarthritis. Recently, many medial pivot knee systems were deigned to replicate the normal knee kinematic: a highly congruent medial compartment and a less conforming lateral tibial plateau characterize these devices. A slightly asymmetric soft tissue balancing is mandatory using medial pivot designs to obtain a correct and physiological knee biomechanics leading good outcomes and long survival rates. This article describes a new surgical technique using a modern third generation TKA design combined with wireless load-sensor tibial trials to improve the correct knee load balancing with a minimal conformity of the polyethylene insert. The use of wireless load-sensing tibial trials has several benefits: it is an intraoperative, objective and dynamic tool allowing surgeons to optimize in real time soft tissue balancing. The meaning of a "truly balanced knee" is still a controversial issue in the current literature.

Keywords: Alignment; Instability; Intraoperative sensors; Knee; Ligament balance; TKA; Total knee arthroplasty.

Fig. 1

VERASENSE, Orthosensor, Dania, FL, USA. Four different thickness are available (10 mm, 12 mm, 14 mm, 17 mm) for TKA intraoperative load sensing testing.

Fig. 2

Left total knee arthroplasty. Intraoperative use of the trial sensing insert.

Fig. 3

Left knee. Loading forces at tibiofemoral interface. In this example, the knee in well balanced with 39 lbs in the medial compartment and 29 lbs in the lateral compartment: the intercompartimental load difference is 10 lbs.

Fig. 4

Right knee. Verasense graphic user interface identifying a stable end point on the medial compartment and a postero lateral roll back during intraoperative passive ROM is noted.