Chief minister Mamata Banerjee underwent a microsurgery on her injured left knee at SSKM Hospital here on Thursday.

She had suffered ligament injuries on her left hip and knee while alighting from a helicopter after an emergency landing near Siliguri on June 27. Since then, Mamata has been undergoing physiotherapy.

A team of doctors led by Rajesh Pramanik, head of the department of physical medicine and rehabilitation, and comprising senior doctors from the radiology department conducted a procedure known as arthroscopy on Mamata.

“A small procedure for arthroscopy was carried out on her left knee to remove synovial fluid that had collected over time. We have advised her to rest for a few days and that will hasten her complete recovery,” said a senior doctor.

Arthroscopy is a surgical procedure that orthopaedic surgeons use to visualize and treat problems inside a joint, doctors said.

A small incision was made on Mamata’s left knee from where a pencil-sized instrument bearing a small lens and light was inserted to see cartilage and ligaments under the kneecap using fibre optic technology, they said.

The fluid was removed with the help of an ultrasound-guided needle.

Mamata reached the SSKM Hospital around 2pm and returned to her Kalighat-residence after the microsurgery.

“We have advised her certain restrictions while at home and she has agreed to abide by all of them,” the senior doctor said.