Osseoperception in transcutaneous osseointegrated prosthetic systems (TOPS) after transfemoral amputation: a...

Endo-exo prosthetics (EEP), which belongs to the transcutaneous osseointegrated prosthetic systems (TOPS), provides an alternative bone-anchored rehabilitation method for transfemoral amputees. It led to the question of whether transmitted forces from prosthetic feet are perceptible by osseoperception resulting in proprioceptive feedback of ground conditions.

The following hypotheses emerged for our trial with the null hypothesis: EEP fitting after transfemoral amputation does not influence osseoperception. Alternative hypothesis 1: EEP patients achieve better osseoperception results than transfemoral amputees fitted with socket prosthesis. Alternative hypothesis 2: EEP carriers achieve comparable results with regards to their osseoperception as non-amputees.

N = 25 patients with EEP (mean age = 50,6 ± 9,4, male/female = 15/10) N = 25 patients with socket prostheses (mean age = 52,6 ± 13,1, male/female = 19/6) and N = 25 healthy volunteers were included in the experimental case-control study. In three blinded test modules (V1, V2, V3), the participants had to identify different degrees of shore hardness (c) of different materials (rubber balls (shore = 5-25c), foam cushions (shore = 5-30c), foam mats (shore = 5-30c) with their prosthetic foot (or a personally defined foot in healthy volunteers) without footwear and had to rank them into the correct order according to their tactile sensation and the degree of hardness. A maximum of 10 points could be scored per run.

This experimental observational study included N = 75 participants. The mean age for the entire cohort was 42.8 ± 16.6 years and the BMI was 26.0 ± 4.8. Our results show a significant level of differences in tactile osseoperception between all groups (p < 0.001). A correlation between the mean values of V1-3 and the PMQ2.0 as well as the mean values of K-Level and the prosthesis wearing time per day showed for PMQ (r = 0.387, p = 0.006) and K-level (r = 0.448, p = 0.001) which is a moderate effect according to Cohen.

Our study results suggest that the EEP treatment can lead to an improvement in tactile sensory perception via the bone-anchored implant, which can lead to an increase in quality of life and improved gait safety.