Single-Camera Markerless Assessment Of Knee Function In Musculoskeletal Physiotherapy: A Narrative Review Of Smartphone And Portable RGB Video Systems

Objective assessment of knee function is a routine component of musculoskeletal physiotherapy.Range-ofmotion (ROM) measurement, observation of functional tasks, and repeated assessment during rehabilitation help clinicians plan treatment and monitor change.Goniometry remains widely used because it is inexpensive and accessible, but measurements may vary with landmark identification, instrument placement, examiner technique, and procedural standardisation [1,2].Smartphone-based goniometers were introduced as a convenient alternative or adjunct, and several studies and systematic reviews have reported good reliability for selected knee ROM measurements [3-5].Performance varies among applications and protocols, however, so evidence obtained for one tool cannot automatically be transferred to another [3,4].A more recent development is the use of video and computervision algorithms for human pose estimation.These systems identify image-based representations of body landmarks, such as the hip, knee, and ankle, and use their relative positions to estimate kinematic variables.This approach underpins contemporary markerless motion capture (MMC) [6,7].