Femoral elevation variability in direct anterior THA: mechanical assessment of a common table-integrated lift system

The direct anterior (DA) approach for total hip arthroplasty (THA) is increasingly used by surgeons. Although Hana traction tables are commonly used in DA THA, no study has quantified the mechanical performance and uniformity of the femur lift. Characterising femoral lift variability is clinically important for patient safety during femoral exposure.

To assess whether femoral lift velocity differs across increasing loads, femur lift laterality, and table age.

7 Mizuho OSI Hana traction tables (14 actuators) were tested using a custom jig and loads between 25 and 100 lb. Lift velocity was measured over 10-second intervals, with 3 averaged trials per weight per actuator. A 2-way repeated-measures ANOVA was used to evaluate applied load and lift laterality, with Tukey post hoc comparisons conducted for significant effects. Pearson's correlation assessed the association between table age and lift velocity.

Lift velocity decreased with increasing load (25 lb: 6.42 ± 0.67 mm/second; 100 lb: 4.89 ± 0.50 mm/second; p < 0.01). No significant differences were observed between left (5.53 ± 0.80 mm/second) and right (5.78 ± 0.73 mm/second) actuators (p = 0.30). At equivalent load conditions, lift velocity differed by up to 39.4% between the fastest and slowest tables. Table age was not significantly correlated with lift velocity. All femur lifts successfully raised the maximum load of 100 lbs through full range of motion.

Femoral lift performance exhibited predictable, load-dependent behavior without evidence of mechanical failure or age-related decline in velocity.Our findings suggest that traction table mechanical underperformance is unlikely to be a major contributor to difficult femoral exposure during DA THA. Continued displacement under high loads highlights the importance of cautious manipulation to prevent injury.