Chondral Knee Injuries

What is it?
A chondral knee injury is the result of articular cartilage damage within the knee. Articular cartilage is a specific elastic connective tissue covering joint surfaces. Viewed by the naked eye, it has a glistening, white appearance. Microscopically, it is composed of water, collagen and a wide array of matrix proteins and lipids.
Articular cartilage has no nerve supplies and therefore does not cause pain or sensitivity when one experiences a mild or early injury.  It also cannot repair itself if damaged. Although symptoms of articular cartilage problems may not present themselves until later in life, they are very common.

The results of chondral lesion
Many factors play a role in chondral knee injuries including the patient's age when the degeneration starts, the patient's activity level, weight and the overall presence of ligament damage.  Although cartilage damage may be in place for years, it sometimes takes a sudden injury to present symptoms.  If no sudden injury occurs, arthritis and osteoarthritis will result after many years of wear and tear and bone-on-bone rubbing. 

Types of lesion.
Chondral damage is graded from mild to severe, and all grades can have characteristics of osteoarthritis.
• Grade 0: normal cartilage
• Grade I: In this early stage, cartilage starts to become soft with swelling
• Grade II: This stage will present a partial-thickness defect with fibrillation (shredded appearance) or fissures on the surface that do not reach the bone or exceed 1.5 cm in diameter.
• Grade III: This stage presents an increased amount of fibrillation and fissuring to the level of subchondral bone in an area with a diameter more than 1.5 cm.  Patients will often complain about noise as the knee bends and soreness or trouble standing from a squatted position.
• Grade IV: This phase will present an exposed subchondral bone—meaning, the cartilage may wear away completely. When the involved areas are large, pain usually becomes more severe, causing a limitation in activity.

The symptoms of a chondral injury resulting from articular cartilage damage will not present themselves as prominently as a torn ACL or meniscus tear.  Similar to other arthritic conditions, the symptoms start mild and continue to progress as time goes on.
Symptoms with articular knee cartilage—once they do begin to appear—include: Intermittent swelling (often the only symptom)-Pain associated with prolonged walking or stair climbing-Buckling or giving way when full weight is placed on the knee-Locking or catching-The knee may make noise during motion.

Diagnosing a chondral injury can be difficult.  Many times, a swollen knee will show a normal exam.  Imaging using an X-ray, MRI or via an arthroscopic examination can help determine if cartilage loss is occurring thus leaving a decrease in space between the bone surfaces.


Articular cartilage degeneration is often treated without surgery. It is recommend weight loss, exercises to strengthen the muscles around the joint, supplements and possibly injections of hyaluronic acid to improve joint lubrication and reduce friction.  There are medications that can be prescribed to help treat symptoms associated with chondral injuries. However, since new growth of cartilage is not a possibility, medication will not cure the condition, but simply allow the patient to live pain-free or more active than before. Further treatment would require a surgical procedure.

Over the past decade, there have been big strides and exciting advancements in the surgical treatment of articular cartilage defects.

Shaving (or Debridement)
This arthroscopic  technique, uses special arthroscopic instruments to smooth the shredded or frayed articular cartilage. Ideally, this treatment will decrease friction and irritation, reducing the symptoms of swelling, noise and pain.


This arthroscopic technique encourages the growth of new cartilage into the defect. This is a well-accepted technique that is a common procedure for patients with damage through the full thickness of articular cartilage. Microfracture surgery is an articular cartilage repair surgical technique that works by creating tiny fractures in the underlying bone. This causes new cartilage to develop from a so-called super-clot. Microfracture surgery has gained popularity in sports in recent years. The surgery is performed by arthroscopy, after the joint is cleaned of calcified cartilage. Through use of an awl, the surgeon creates tiny fractures in the subchondral bone plate. Blood and bone marrow (which contains stem cells) seep out of the fractures, creating a blood clot that releases cartilage-building cells. The microfractures are treated as an injury by the body, which is why the surgery results in new, replacement cartilage. The procedure is less effective in treating older patients, overweight patients, or a cartilage lesion larger than 2.5 cm. Further on, chances are high that after only 1 or 2 years of the surgery, symptoms start to return as the fibrocartilage wears away, forcing the patient to reengage in articular cartilage repair.
The effectiveness of cartilage growth after microfracture surgery is thought to be dependent on the patient's bone marrow stem cell population and some think increasing the number of stem cells increases the chances of success.

Microfracture surgery

Autologous chondrocyte implantation 
Autologous chondrocyte implantation (ACI) is a biomedical treatment that repairs damages in articular cartilage. ACI provides pain relief while at the same time slowing down the progression or considerably delaying ΤΚR. The goal of ACI is to allow people suffering from articular cartilage damage to return to their old lifestyle.

ACI procedures aim to provide complete hyaline repair tissues for articular cartilage repair. Over the last 20 years, the procedure has become more widespread and it is currently probably the most developed articular cartilage repair technique.

This cell based articular cartilage repair procedure takes place in three stages. In a first stage, between 200mg  cartilage is sampled arthroscopically from a non weight bearing area. The matrix is removed enzymatically and the chondrocytes isolated. These cells are grown in vitro in a specialized laboratory for approximately four to six weeks, until there are enough cells to re-implant on the damaged area of the articular cartilage. The patient then undergoes a second treatment, in which the chondrocytes are applied on the damaged area during an open-knee surgery. These autologous cells should adapt themselves to their new environment by forming new cartilage. During the implantation, chondrocytes are applied on the damaged area in combination with a membrane as a scaffold matrix.


Τhe OATS procedure or mosaicplasty
The OATS procedure, an abbreviation for osteoarticular transfer system, is a surgical procedure used to treat focal cartilage defects. OATS is one technique of several used to treat this problem; the type of procedure is called a mosaicplasty.

A mosaicplasty uses cartilage from undamaged areas of the joint, and moves this cartilage to a damaged area. This type of procedure is only useful for the treatment of focal cartilage damage. This means the widespread damage of cartilage seen in osteoarthritis cannot be treated with mosaicplasty. This treatment is only used for isolated areas of cartilage damage, usually limited to 10-20 mm in size. This type of damage is usually seen in younger patients (less than 50 years old) who experience a trauma to their joint.