| Summary: | BACKGROUND Transfemoral bone-anchored prostheses (BAP) fitted with microprocessor-controlled knees (MPKs) can contribute to increase efficacy and safety of osseointegrated implants (e.g., auto adaptive stance and swing control, stumble recovery, push off functions) [1]. Preliminary studies showed that loading boundaries applied by BAP fitted with selected basic and state-of-the-art components during standardized daily activities were significantly smaller than the ones applied during a fall [2-4]. There is a need for more quantitative evaluations of the safety of BAP fitted with state-of-the-art components. AIM This study tested the hypothesis that the regular load applied of osseointegrated implant by BAP fitted with Power Knee (ÖSSUR, Iceland) have a margin of safety unlikely to compromise healthy bone/implant coupling. METHOD Twenty participants fitted with a press-fit transfemoral osseointegrated implant participated in this study (4F/16M, 59±14 yrs, 1.74±0.10 m, 89.04±17.20 kg). Loading boundaries were measured during walking, ascending and descending ramp and stairs at self-selected pace with the tri-axial transducer (iPecsLab, RTC Electronics, USA). Maximum loads were conservatively extracted from a study reporting internal constraints applied on femur of able-bodied during running [5]. Factor (FoS) and margin (MoS) of safety were calculated for forces (F) and moments (M) applied on long (LG), anteroposterior (AP) and mediolateral (ML) axes expressed as percentage of bodyweight (BW). A MoS≥3 was deemed unlikely to compromise the integrity of bone/implant coupling. RESULTS The overall minimum and maximum load applied on the implant across all activities (2,155 steps) ranged between -305 N and 1,258 N or -32 %BW and 147 %BW on FLG, -331 N and 224 N or -47 %BW and 25 %BW on FAP and -47 N and 234 N or -6 %BW and 21 %BW on FML as well as -17 Nm and 19 Nm or -2.2 %BWm and 2.0 %BWm on MLG, -74 Nm and 20 Nm or -6.6 %BWm and 2.0 %BWm on MAP-82 Nm and 91 Nm or -10.3 %BWm and 9.9 %BWm on MML, respectively. As ...
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