This document discusses periarthritis shoulder, also known as frozen shoulder or adhesive capsulitis. It has three stages: a painful freezing stage with night pain and limited range of motion, an adhesive frozen stage with more loss of shoulder motion, and a recovery thawing stage with gradual improvement in range of motion. Physiotherapy aims to reduce pain, improve mobility and strength, and increase capsular extensibility through techniques like pendular exercises, towel stretches, and special tests like the shoulder shrug and Apley scratch tests to assess range of motion. The condition involves inflammation around the shoulder joint capsule and surrounding soft tissues, restricting both active and passive shoulder motion.