Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions?

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Medical Engineering

Background:

• Total hip replacement (THR) aims to restore function and reduce pain.
• Optimizing prosthetic alignment is crucial for long-term implant survival and patient mobility.
• Conventional THR techniques may not always achieve optimal component positioning.

Purpose of the Study:

• To evaluate the efficacy of a novel computer-assisted surgery (CAS FF) method for minimal-invasive THR.
• To compare hip joint reaction forces and gait parameters between CAS FF and conventional THR (CON).
• To assess functional improvements in patients undergoing CAS FF versus CON.

Main Methods:

• A prospective study involving 60 patients undergoing minimal-invasive THR (28 CAS FF, 32 CON).
• Gait analysis was performed preoperatively, and at 6 and 12 months postoperatively.
• Patient-specific musculoskeletal models were used to analyze hip reaction forces (magnitude, symmetry, orientation) and gait parameters.

Main Results:

• The CAS FF group exhibited hip reaction forces closer to those of young healthy individuals.
• Increased phase-shift symmetry was observed in the CAS FF group.
• Improved hip reaction force orientation towards optimal alignment was noted in the CAS FF group, without adverse edge or rim-loading.

Conclusions:

• The computer-assisted "femur first/combined anteversion" (CAS FF) method demonstrates potential for improving hip joint reaction forces and gait parameters post-THR.
• CAS FF shows an early improvement in hip reaction force orientation with a trend towards better long-term outcomes compared to conventional THR.