Reproducibility and validity of the 3D L.A.S.A.R. posture alignment system in persons with a transtibial...

During the alignment process, the 3D Laser Assisted Static Alignment Reference (L.A.S.A.R.) is clinically used to objectively aid rehabilitation teams to optimize static prosthetic alignment. Although this device is used routinely within the clinic, its reliability and validity are unknown.

To assess the test-retest reproducibility and concurrent validity of the 3D L.A.S.A.R.

Clinimetric study.

In this cross-sectional study, participants using a unilateral transtibial bone-anchored prosthesis were recruited by convenience sampling. Reproducibility was assessed by calculating reliability (intraclass correlation coefficients [ICC]) and agreement parameters (standard error of measurement, smallest detectable change, and limits of agreement). Concurrent validity was assessed through ICC and limits of agreement.

The reliability parameters (ICCagreement) ranged from 0.86 to 0.97, with a standard error of measurement (%) of 6.5%‒29.5% in 2D mode and 5.3%‒23.9% in 3D mode and smallest detectable change (%) of 17.9%‒81.6% in 2D mode and 14.6%‒66.1% in 3D mode with no systematic bias. Concurrent validity (ICCconsistency) ranged from 0.11 to 0.87, with systematic bias found between both systems in several perspectives.

The 3D L.A.S.A.R. shows very good to excellent test-retest reliability. However, the measurement errors exceeded clinically considerable deviations. Concurrent validity ranged between poor to very good. Further development of the 3D L.A.S.A.R. and research focusing on clinimetric properties such as responsiveness or interrater reliability is needed.