Cartilage Injuries and Autologous Chondrocyte Implantation (ACI)

Articular Cartilage Lesions causes roughening of the joint surface and can cause arthritis of the joint. Sometimes, the lesion can be deep enough exposing the bony surface. This can cause severe pain on weight bearing.


Articular Cartilage Lesions are classified from Grade 1 to 4 depending on the severity of the lesion. A grade 4 lesion is a full thickness lesion with bone exposed. Minor lesions may not cause any symptoms.

These lesions can occur due to injury, but more commonly are a result of wear and tear within the knee.


  • Diagnosis is generally done by MRI scans.
  • Severe, long standing lesions which have caused progression to arthritis can be visualised on an x-ray.

Treatment Procedures

There are different types of treatment which can be offered, mostly by arthroscopic surgery (Key-hole procedure). Long-term studies are still awaited for cartilage regeneration surgeries, however short term studies have been shown to be promising.

Some of the procedures which have been described are:

  • Arthroscopic debridement- Here the loose bits of cartilage are excised by arthroscopic surgery. This is mainly to clean up the joint and generally has only a short term effect.
  • Microfracture technique- This is usually performed in lesions where the underlying bone is exposed and the lesion fairly large. An awl is used to make small holes in the bone in multiple sites. This is done to incite a healing response and blood vessels start growing towards the surface and produce fibro cartilage (scar tissue) to cover the defect and hence help in pain relief.
  • Autologous chondrocyte implantation (ACI) - This is recently developed method for cartilage regeneration which is usually recommended for younger individuals. Results have been shown to be better in smaller, well localised lesions. It is usually a staged procedure and consists of 2 procedures with a gap of about 6 weeks. The first surgery is to harvest healthy cartilage from non-weight bearing portion of the knee. These cells are then grown in a lab to a larger volume.

Rehabilitation after surgery usually involves a continuous passive motion device to mobilise the knee. This helps to avoid joint stiffness. The limit to which patients will be allowed to move the joint depends on the site at which the cartilage has been repaired. Emphasis is to avoid putting strain on the repair site. Once reasonable movement has been achieved, strengthening exercises are started. Weight bearing status will again be determined by the surgeon depending on the position of the repair site.