The biomechanical effect of different spring extension assist mechanisms in mechanical 4-bar polycentric prosthetic knees for unilateral above/through-knee amputees.

The study included only eight participants, which limits statistical power and generalizability to the wider amputee population. Familiarization with the new prostheses occurred only on the day of data collection, whereas typical adaptation takes longer. Seven participants normally used microprocessor-controlled knees, which may have influenced their biomechanical data when switching to mechanical knees. The study compared only two established knee designs without specifying brands, and did not explore combinations of other design variables like friction or spring stiffness. Gait analysis alone does not capture all functional aspects, such as sitting stability, which may differ between the designs.

The study was funded by the Royal British Legion Centre for Blast Injury Studies and UKRI. The authors stated that they compared two established prosthetic knees without specifying the brands to prevent conflicts of interest.

Do not assume that improved gait symmetry and reduced knee flexion will lead to faster walking or better overall function. The study found no significant difference in walking speed at self-selected speeds, and the clinical significance of the symmetry improvement is not fully known. The sample size was small and familiarization was brief, so these biomechanical changes may not translate to meaningful daily life improvements for all patients.