The European champion with Portugal sustained the knee injury following a challenge from France’s Dimitri Payet in the Euro 2016 final last week.
No confirmation has been given on the length of time Ronaldo will be sidelined, but he is expected to miss games against Paris Saint-Germain, Chelsea and Bayern Munich on Real Madrid’s pre-season tour of the USA.
The 31-year-old could also miss the UEFA Super Cup against Sevilla in Trondheim on August 9, meaning he will start the 2016/17 season without any pre-season under his belt.
Ronaldo has now visited a clinic while on holiday in Ibiza for hyperbaric oxygen therapy in an attempt to speed up his recovery.
“Thanks to hyperbaric medicine the regeneration of tissue and recovery from injury is stimulated, reducing the risk of future injury and physical deterioration,” a spokesperson for the Clinica Evidental told Marca.
“This speeds up the recovery time. Today this is one of the most effective complementary therapies in injury recovery.”