Can the need for soft tissue release in total knee replacement be predicted pre-operatively? A study based on surgical navigation

Abstract

Introduction In complex and deformed knees, soft tissue release (STR) is required to obtain symmetry in the femorotibial gap. The objective of this study was to attempt to predict the need for soft tissue release using surgical navigation in total knee replacement (TKR). Methods Prospective and non-randomized study. One hundred thirty knees. At the start of navigation, an attempt was made to correct the femorotibial mechanical axis by applying force to the medial or lateral side of the knee (varus-valgus stress angle test). A gap balanced technique with computer-assisted surgery (CAS) was performed in all cases. The ligaments were tensioned, and using CAS visualization and control, progressive STR was performed in the medial or lateral side until a symmetry of the femorotibial gap was achieved. Results Eighty-two patients had a varus axis ≥ 3° and 38 had a valgus axis (P < 0.001). STR was performed under navigation control in 38.5% of cases, lateral release (LR) in 12 cases, and medial release (MR) in 38 cases. After performing the varus-valgus stress angle test (VVSAT), the axis of 0° could be restored at some point during the manoeuvre in 28 cases. STR was required in 44.6% of varus cases and 27% of valgus cases (P = 0.05). A significant relationship was found between the previous deformity and the need for MR (P < 0.001) or LR (P = 0.001). STR was more common in male patients (P = 0.002) and as obesity increased. Conclusion This study shows that pre-operative factors favouring the need to perform STR in a TKR implant can be defined.

Constitutional alignment predicts medial ligament balancing in mechanically aligned total knee arthroplasty for varus knees

“…Stress radiographs enable better determination, but in this study, no difference in VVD was found between those who required MNP and those who did not. Other preoperative factors which have been described include gender and BMI but our findings did not concur [2].…”

“…In the literature, preoperative deformity, whether assessed on LLRs or with computer‐assisted surgery, has been shown to predict gap asymmetry requiring soft tissue release [2, 12]. However, these studies focussed on extension gap asymmetry and did not consider flexion gap asymmetry as a separate entity.…”

Postoperative limb alignment in total knee replacement. Conventional versus navigated versus robotic techniques

“…This is a closed navigation system, that generates three-dimensional models of the femur and tibia using a bonemorphing algorithm that deforms a statistical shape model of the knee joint to match the patient's femoral and tibial bone surfaces without the need of preoperative imaging. Bone cuts were performed using manually adjusted guides, following the parameters obtained by the navigation system [33][34][35][36][37] Tracking arrays were rigidly attached to the femur and tibia. The software created the knee model based on a kinematic calculation of the centre of the femoral head and a manual mapping of the centre of knee and ankle and the joint surfaces of the femur and tibia.…”