patient support and positioning system for continuous passive motion machines comprising a fully adjustable chair to which is attached a horizontal telescoping arm having a coupling member for fastening the vertical stand of a cpm machine thereto . the chair has full adjustment in all axes : rotation around a vertical center axis ; vertical height adjustment ; fully adjustable seat back , both fore - and - aft and vertically for proper lumbar support ; and tilt of the seat . the telescoping arm is lockably adjustable in length to provide proper center - to - center distance between the center post of the chair and the cpm machine support . the arm further includes a downward vertical step member at its outboard cpm machine connecting end to permit proper vertical alignment of the cpm machine for users having a short torso . the arm also provides a support for a cpm power supply / control unit , and has means for securing the power cord out of the way off the floor . the invention permits support of the patient with a full range of adjustment so that the patient can have proper positioning for selected exercise of the selected extremity in flexion / extension , forward flexion / extension internal / external rotation , supination / pronation and the like .