Validation of IMU against optical reference and development of open-source pipeline: proof of concept case report in a participant with transfemoral amputation fitted with a Percutaneous Osseointegrated Implant

Table 4 a Relative measure of fit. b Relative measure of fit

nRMSE and IQR of joint angles between systems
Joint / spatiotemporal measure	nRMSE (%)
Joint / spatiotemporal measure	TFA Amputated	IQR	TFA Intact	IQR	Without amputation	IQR
Pelvis Flexion/Extension (tilt)	113.14	73.77	132.48	75.59	66.86	61.45
Pelvis Hike/Drop (list)	14.52	6.99	13.29	4.80	26.53	4.86
Pelvis Internal/External rotation	27.69	12.23	26.10	11.11	14.62	14.10
Hip Flexion/Extension	13.27	8.15	14.98	12.14	3.43	1.29
Hip Adduction/Abduction	11.84	7.36	69.37	26.35	27.84	8.22
Hip Internal/External Rotation	18.01	13.51	18.55	12.80	24.32	11.35
Knee Flexion/Extension	2.91	0.94	3.89	0.88	2.18	0.37
Ankle Dorsi/Plantarflexion	6.43	5.72	32.59	11.56	13.67	4.80
Foot progression angle	–	–	–	–	–	–
Average	25.97	16.08	38.83	19.40	22.43	13.31

Plane and joint level nRMSE and radar plot between systems
nRMSE (%)
		TFA Amputated	TFA Intact	Combined	Without amputation
Plane	Sagittal	33.94	44.48	39.21	21.54
	Coronal	13.18	41.33	27.26	27.18
	Transverse	22.85	22.33	22.59	19.47
Joint level	Pelvis	51.78	57.29	54.54	36.01
	Hip	14.37	34.30	24.34	18.53
	Knee	2.91	3.89	3.40	2.18
	Ankle	6.43	26.55	16.49	13.67

Radar plot key: Green = TFA amputated side. Purple = TFA intact side. Black = TFA combined. Orange = without amputation

ISSN: 1743-0003