Extension and Flexion Gap Balancing and Its Correlation With Alignment in Navigated Total Knee Arthroplasty

Abstract

Computer-assisted surgery was developed to improve the results of conventional total knee arthroplasty (TKA). The authors investigated the preoperative varus/valgus deformity influence on the production of balanced extension and flexion gaps using computer-assisted surgery. This study evaluated data from a prospective case series. A total of 132 patients (107 women and 25 men) underwent navigated TKA. Patients were divided into the following 3 groups according to the degree of the initial varus/valgus deformity: group 1, 0° to 3°; group 2, 3° to 9°; and group 3, greater than 9°. The final lower limb mechanical axis (LLMA) and the final flexion and extension gaps were measured. Knees exhibiting up to 3° of deviation on the frontal plane and a difference of up to 3 mm between the lateral and medial gaps were considered to be aligned and balanced, respectively. Average LLMA deviation decreased from 5.58° (± 4.80°) to 1.87° (± 1.66°). For knees with varus deviation, the percentage of balancing relative to the flexion gaps was 97.8% and that relative to the extension gap was 100% (P>.05). For knees with valgus deviation, the percentage of balancing relative to the flexion gaps was 95.1% and that relative to the extension gap was 97.6% (P>.05). Approximately 92% of the LLMA alignment was achieved in the group with varus deformity, whereas 71.4% was observed in the group with valgus deformity (P<.05). Computer-assisted TKA could attain proper flexion and extension balance regardless of coronal plane malalignment magnitude. Severe valgus and varus knees are more difficult to align using navigation. No difference was found in the balance of flexion or extension gaps in valgus or varus knees, independent of the severity.

Is gap balancing superior to measured resection technique in total knee arthroplasty? A meta-analysis

“…Gap balancing resulted in 1.27 mm more joint line elevation on average compared with measured resection. The raised joint line with gap balancing can be attributed to this technique's prioritization of gap symmetry [6,38,39]. Although not included in the meta-analysis, measured resection was found to be two-fold risky to suffer femoral condylar lift-off compared with gap balancing [23].…”

Dynamic Alignment Analysis in the Osteoarthritic Knee Using Computer Navigation

“…In TKA, assessment of the laxity is critical information and a routine component during the surgical procedure. 3,4,13,15,16,[18][19][20][21]23,24,27,31,32,37,38 We have developed a reproducible method when using navigation systems, representing the first step in this line of investigation, and are committed to increasing the relevance of the quantitative data provided by navigation systems, especially in postoperative analysis.…”

“…[11][12][13][14][15][16][17] Computer-assisted navigation has been developed to provide surgeons quantitative measurement tools for real-time assessment of lower limb alignment and kinematics. [18][19][20][21][22][23][24][25][26][27] The purpose of this study is to determine the dynamic coronal FTMA in osteoarthritic knees using computer navigation. We hypothesize that there are different varus-valgus patterns between flexion and extension in the osteoarthritic knee.…”

Review of the Relationship Between Knee Alignment and Fixed Flexion Deformity and How This Can Influence Total Knee Arthroplasty: A Retrospective Cohort Study

“…18 Pre-existing severe valgus and varus deformities can make intra-operative alignment more challenging during navigated TKA. 5 Pre-operative varus deformity not only impacts ligament balance and intra-operative soft tissue release, but is also associated with poorer outcomes postoperatively. 13 , 15 , 17 Patients with severe varus or valgus deformity are also at risk of chronic instability if the deformity is not corrected or if there has been excessive soft tissue release during TKA.…”