Comparison of Three Circular Frames in Lower Limb Deformity Correction: A Biomechanical Study

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Device Technology

Background:

• Circular frames are established tools for correcting lower limb deformities.
• Recent advancements include three new frames: Taylor Spatial Frame (TSF), Truelok Hexapod System (TL-HEX), and Orthex.
• This study evaluates their comparative accuracy and efficiency in correcting long bone deformities.

Purpose of the Study:

• To compare the accuracy and efficiency of TSF, TL-HEX, and Orthex circular frames.
• To assess deformity correction in simulated distal femur valgus and proximal tibia varus.
• To evaluate residual deformity and reprogramming frequency among the three frames.

Main Methods:

• A biomechanical study using Sawbones models with simulated 30° valgus (distal femur) and varus (proximal tibia) deformities.
• Application of TSF, TL-HEX, and Orthex frames using standard surgical techniques.
• Radiographic assessment and software-based deformity estimation before and after correction.
• Comparison of residual deformity, accuracy of software estimation, and frequency of strut adjustments.

Main Results:

• All frames corrected 30° deformities with residual angulation below 5° (Orthex: 1°, TSF: 2.5°, TL-HEX: 3°).
• Truelok Hexapod System (TL-HEX) software showed statistically significant superior deformity analysis compared to Orthex and TSF.
• No significant differences were found in residual deformity or strut adjustment frequency among the three frames.

Conclusions:

• The TSF, TL-HEX, and Orthex frames are comparable in correcting lower limb deformities.
• The TL-HEX system's software offers more accurate deformity analysis, though the clinical significance is minimal.
• All evaluated frames provide effective solutions for long bone deformity correction.