What is the Effect of Posterior Osteophytes on Flexion and Extension Gaps in Total Knee Arthroplasty? A Cadaveric Study

Abstract

Background: Posterior compartment knee osteophytes may pose a challenge in achieving soft-tissue balance during total knee arthroplasty (TKA). Obtaining symmetry of flexion and extension gaps involves balance of both bony and soft-tissue structures. We hypothesize that space-occupying posteromedial femoral osteophytes affect soft-tissue balance. Methods: Five cadaveric limbs were acquired. Computed tomography scans were obtained to define the osseous contours. Three-dimensionally printed, specimen-specific synthetic posterior femoral osteophytes were fabricated in 10-mm and 15-mm sizes. TKAs were implanted. Medial and lateral compartment contact forces were measured during passive knee motion using pressure-sensing technology. For each specimen, trials were completed without osteophytes and with 10-mm and 15-mm osteophytes affixed to the posteromedial femoral condyle. Contact forces were obtained at full extension, 10 , 30 , 45 , 60 , and 90 of flexion. These were recorded across each specimen in each condition for three trials. Tukey post hoc tests were used with a repeated measures ANOVA for statistical data analysis. Results: The presence of posteromedial osteophytes increased asymmetric loading from full extension to 45 of flexion, with statistically significant differences observed at full extension and 30 . A reduction in lateral compartment forces was noted. The 25%-75% bounds of variability in the contact force was less than 3.5 lbs. Conclusions: Posteromedial femoral osteophytes caused an asymmetric increase in medial contact forces from full extension continuing into mid-flexion. The soft-tissue imbalance created from these osteophytes supports their removal before performing ligament releases to obtain desired soft-tissue balancing during TKA.

Ligament Tension and Balance before and after Robotic-Assisted Total Knee Arthroplasty — Dynamic Changes with Increasing Applied Force

“…These differences may be due to the influence of preoperative flexion contracture, or a tight posterior capsule in extension due to posterior osteophytes, which increase knee stiffness and limit ROM in extension and early flexion. 22 Posterior capsule releases, posterior osteophyte removal, and implant trialing performed after femoral resection to increase passive knee extension may explain why knee stiffness was more uniform throughout flexion post-resection. 23 Furthermore, Bellemans et al reported that ligament stress relaxation does occur perioperatively during the course of a TKA procedure and results in an increase in mediolateral gaps of 1 mm and an increase in maximal passive extension of 3 degrees.…”

Large Osteophytes over 10 mm at Posterior Medial Femoral Condyle Can Lead to Asymmetric Extension Gap Following Bony Resection in Robotic Arm–Assisted Total Knee Arthroplasty with Pre-Resection Gap Balancing

“…However, for osteophytes >10 mm, the ME gap increased more asymmetrically than the LE, MF, and LF gaps ( p < 0.05). Holst et al [ 20 ] conducted a cadaveric study to evaluate the effects of 10 mm and 15 mm 3D-printed osteophyte-mimicking blocks on the medial and lateral contact forces using Verasense (OrthoSensor-Dania Beach, FL, USA). Although there were no significant differences between the 10 mm and 15 mm blocks on the medial contact forces, the presence of blocks caused an asymmetric contact force between the ME and LE.…”