ObjectiveAdvances in computer vision make it possible to combine low-cost cameras with algorithms, enabling biomechanical measures of body function and rehabilitation programs to be performed anywhere. We evaluated a computer vision system's accuracy and concurrent validity for estimating clinically relevant biomechanical measures.DesignCross-sectional study.SettingLaboratory.ParticipantsThirty-one healthy participants and 31 patients with axial spondyloarthropathy.InterventionA series of clinical functional tests (including the gold standard Bath Ankylosing Spondylitis Metrology Index tests). Each test was performed twice: the first performance was recorded with a camera, and a computer vision algorithm was used to estimate variables. During the second performance, a clinician measured the same variables manually.Main measuresJoint angles and inter-limb distances. Clinician measures were compared with computer vision estimates.ResultsFor all tests, clinician and computer vision estimates were correlated (r2values: 0.360–0.768). There were no significant mean differences between methods for shoulder flexion (left: 2 ± 14° (mean ± standard deviation),t= 0.99,p< 0.33; right: 3 ± 15°,t= 1.57,p< 0.12), side flexion (left: − 0.5 ± 3.1 cm,t= −1.34,p= 0.19; right: 0.5 ± 3.4 cm,t= 1.05,p= 0.30) and lumbar flexion ( − 1.1 ± 8.2 cm,t= −1.05,p= 0.30). For all other movements, significant differences were observed, but could be corrected using a systematic offset.ConclusionWe present a computer vision approach that estimates distances and angles from clinical movements recorded with a phone or webcam. In the future, this approach could be used to monitor functional capacity and support physical therapy management remotely.