Knee injuries are common, particularly among individuals with an active lifestyle. One of the most severe forms of these injuries is damage to the cartilage within the knee joint. Cartilage plays a critical role in ensuring smooth and pain-free joint movement. Without proper treatment, cartilage injuries can lead to severe pain, limited mobility, and, in the long term, knee osteoarthritis.
This article explores the definition of cartilage injuries in the knee, possible treatment options, and modern surgical techniques. My aim is to provide an in-depth understanding of this prevalent yet complex issue and to help affected individuals choose the most suitable treatment path.
What is Cartilage?
Cartilage is a strong yet flexible connective tissue that protects our joints and bones. Wherever it exists in the body, cartilage acts as a shock absorber. In our joints, cartilage reduces friction, preventing the surfaces of the joints from wearing out during movements such as walking, sitting, standing, or running.
There are three types of cartilage in the human body:
Hyaline Cartilage:
The most common type of cartilage in the body.
It covers the surfaces of bones that form joints and is referred to as articular cartilage.
Hyaline cartilage is smooth and slippery, allowing for seamless joint movement. Despite being flexible, it is also strong enough to maintain joint shape during high-impact activities like jumping.
Hyaline cartilage is primarily found in:
Joint surfaces
Rib cartilage
Nose cartilage
Elastic Cartilage:
The most elastic type of cartilage.
Found in structures like the ear and larynx, where flexibility is needed. For instance, it allows the ear to return to its original shape after being bent.
Fibrocartilage (Fibrous Cartilage):
The strongest and toughest type of cartilage in the body.
It acts as a shock absorber and connects structures in the body.
Examples include:
Menisci in the knee
Intervertebral discs in the spine
Tendons, muscles, and ligaments containing fibrocartilage
When articular cartilage (hyaline cartilage) in the body is damaged, it may heal with fibrocartilage.
What is Knee Joint Cartilage?
The tissue covering the ends of the bones that form joints is called joint cartilage. It is composed of hyaline cartilage. The primary function of joint cartilage is to provide a smooth surface that prevents the bones from rubbing against each other and causing damage during movement.
Like all joint cartilage, knee joint cartilage lacks its own blood vessels and is nourished by synovial fluid. The cells within the cartilage (chondrocytes) are responsible for maintaining its structure. Additionally, joint cartilage contains a high amount of fluid, making its surface slippery and reducing the risk of damage during movement. You can think of it as similar to the lubrication system in a car engine.
What is Knee Joint Cartilage Damage?
nee joint cartilage damage refers to injuries to the cartilage surface that forms the knee joint.
This type of damage can occur due to:
Direct trauma, such as falls or impacts.
Kneecap dislocations, where the patella collides with other cartilage surfaces in the knee, causing damage.
Abnormal bone movement, such as when the femur and tibia rub against each other during anterior cruciate ligament (ACL) tears.
Another form of cartilage damage occurs without trauma, as seen in knee osteoarthritis. In osteoarthritis, cartilage damage progresses gradually, eventually compromising all the cartilage in the joint. This degenerative condition is often caused by genetic factors.
Which Sports are More Prone to Knee Joint Cartilage Injuries?
Cartilage injuries in the knee joint are more common in sports that involve sudden stops and directional changes, such as:
Soccer
Basketball
Volleyball
Contrary to popular belief, cartilage damage is rarely seen in sports like running and cycling.
Grading of Knee Joint Cartilage Damage
Orthopedic specialists classify the severity of cartilage damage in the knee using the Outerbridge Arthroscopic Grading System, which evaluates the extent of damage based on arthroscopic findings. This system helps determine the appropriate treatment approach.
Outerbridge Arthroscopic Grading System:
Grade 0: Normal cartilage.
Grade 1: Softening and swelling of the cartilage.
Grade 2: Partial-thickness cartilage loss with surface cracks.
Grade 3: Full-thickness cartilage loss up to 1.5 cm in diameter, with deep cracks reaching the subchondral bone.
Grade 4: Complete cartilage loss, exposing the subchondral bone.
What Are the Symptoms of Knee Joint Cartilage Damage?
Symptoms of knee joint cartilage damage include:
Pain
Knee locking
A sensation of the knee giving way
Swelling and tenderness
Inability to continue sports activities
Loss of range of motion in the knee joint
What is a Loose Body?
In cases of acute knee trauma or knee osteoarthritis, a fragment of cartilage can break off from the joint surface. If this fragment becomes completely detached and floats freely within the knee joint, it is referred to as a loose body.
Patients with a loose body often experience mechanical symptoms such as locking or giving way in addition to pain and swelling.
How is Knee Joint Cartilage Damage Diagnosed?
Diagnosis begins with a detailed patient history, particularly focusing on any recent knee trauma. This is followed by a physical examination. Imaging studies such as X-rays and MRI scans are then used to determine the presence, location, and extent of cartilage damage.
How is Knee Joint Cartilage Damage Treated?
Treatment planning for knee joint cartilage damage involves a detailed assessment of MRI images to answer the following key questions:
What is the size and depth of the injured cartilage area?
Where is the injury located (is it in a weight-bearing area)?
Has the damaged cartilage fragment detached and fallen into the joint?
If the fragment is still attached, is it at risk of detachment (is the fragment stable)?
Non-Surgical Treatment of Knee Joint Cartilage Damage
Non-surgical treatment for cartilage damage in the knee is controversial and is generally considered in cases where the cartilage damage is minimal and symptoms are mild. These methods include:
Managing pain and observing the condition.
Avoiding weight-bearing on the knee for a specific period using crutches.
Strengthening the muscles around the knee through physiotherapy and exercise.
Modifying daily activities to avoid pain.
Weight loss.
Biological treatments such as PRP, PRGF, Sanakin, or stem cell therapy (from fat or bone marrow).
Surgical Treatment of Knee Joint Cartilage Damage
Considerations Before Deciding on Surgery for Cartilage Damage
Mechanical Alignment of the Knee:
Before deciding on cartilage surgery, it is essential to evaluate whether there is any malalignment in the knee, such as bowlegs (genu varum) or knock knees (genu valgum).
Cartilage surgeries performed without addressing malalignment are likely to fail.
Typically, alignment correction surgeries and cartilage surgeries can be performed in the same session.
Cartilage Damage in the Patella:
Cartilage damage in the kneecap (patella) often occurs due to a history of patellar dislocation.
If patellar dislocation is the underlying cause of cartilage damage, additional surgeries to prevent future dislocations may be required.
Without addressing this issue, cartilage surgery alone will not be effective.
For detailed information on patellar dislocations, visit:
Surgical Options Based on the Size and Location of Cartilage Damage
The choice of surgical technique depends on two critical factors:
The size of the damaged cartilage area.
The location of the damage within the knee joint.
Cartilage Damage in the Femoral Condyles (Weight-Bearing Areas):
If the cartilage damage is less than 4 cm²: Options include microfracture or mosaicplasty.
If the cartilage damage is greater than 4 cm²: Options include autologous cartilage transplantation or osteochondral allograft transplantation.
Cartilage Damage in the Patellofemoral Joint (Kneecap Area):
If the cartilage damage is less than 4 cm²: Options include microfracture or mosaicplasty.
If the cartilage damage is greater than 4 cm²: Options include autologous cartilage transplantation.
Types of Surgical Procedures for Knee Joint Cartilage Damage
Arthroscopic Debridement: Cleaning of damaged cartilage surfaces.
Cartilage Fragment Fixation Surgery: Reattaching a detached cartilage fragment.
Arthroscopic Microfracture: Stimulating cartilage repair through small bone perforations.
Mosaicplasty: Transplanting healthy cartilage plugs to the damaged area.
Osteochondral Allograft Transplantation: Transplanting cartilage and bone from a donor.
Autologous Cartilage Transplantation: Using the patient’s own cartilage cells for repair.
Particulated Juvenile Cartilage Transplantation: Implanting cartilage fragments from juvenile donors.
Stem Cell Therapy: Injecting stem cells to promote cartilage regeneration.
Arthroscopic Debridement
This minimally invasive surgery involves using a camera (arthroscope) to enter the joint and remove any loose fragments or damaged cartilage that may cause mechanical issues such as locking or catching.
It is a frequently performed procedure for partial-thickness cartilage injuries. Patients with mechanical problems like locking or catching benefit greatly in the short term. The procedure is quick, allowing patients to return to their normal activities rapidly with minimal recovery time.
Cartilage Fragment Fixation Surgery
In this procedure, a detached cartilage fragment is reattached to its original position using screws or pins. The goal is to promote healing of the detached cartilage-bone fragment.
Ideal Candidates:
Patients whose growth plates have not yet closed, meaning their bone growth is still active, have a higher chance of success.
Fragments containing subchondral bone (the layer beneath the cartilage) also improve healing potential.
Special Case: Osteochondritis Dissecans (OCD)
If the fragment includes subchondral bone, the condition is called Osteochondritis Dissecans (OCD).
Fixation surgery is the ideal treatment for OCD and offers a higher chance of recovery.
For more information about OCD, visit: [Link Placeholder]
Fixation Materials:
Absorbable bio-screws or headless metal screws are used for fixation.
Metal screws must be removed 6–9 months after the healing process is complete.
Arthroscopic Microfracture
This procedure is suitable for patients with cartilage damage smaller than 4 cm². The aim is to stimulate the formation of reparative tissue by allowing bone marrow content to reach the damaged cartilage area.
Procedure:
Performed arthroscopically (minimally invasive).
The damaged cartilage area is cleaned (debridement), and small holes approximately 1 mm in diameter are made in the exposed bone using a specialized tool.
The holes are spaced 3–4 mm apart to ensure proper healing.
Postoperative Care:
Weight-bearing is restricted for approximately 5–6 weeks.
During this period, patients must use crutches to avoid putting weight on the operated leg.
Mosaicplasty (Osteochondral Autografting)
In a mosaicplasty procedure, the damaged cartilage is first cleaned. Healthy cartilage, along with the underlying bone, is then transplanted to the damaged area. The grafted healthy cartilage is taken from a non-weight-bearing area of the knee joint. Harvesting from this area does not cause any issues.
The harvested grafts are cylindrical plugs, which are placed into cylindrical holes created in the damaged cartilage area. Depending on the extent of the damage, one or more cylindrical plugs may be used.
To watch a mosaicplasty surgery performed by Dr. Utku Erdem Özer, click the following link:Watch the Surgery
Osteochondral Allograft Transplantation
In cases where there is extensive cartilage damage in the knee joint, cartilage-bone tissue is transplanted from a donor (cadaver). This procedure is similar to mosaicplasty, but the graft is sourced from a cadaver rather than the patient’s own body.
The grafted cartilage-bone piece is shaped to fit the defect in the cartilage, ensuring proper coverage of the damaged area.
Autologous Chondrocyte Implantation (Cartilage Transplantation)
This technique involves two separate surgeries:
First Surgery:
A minimally invasive procedure is performed to harvest a small piece of healthy cartilage from a non-weight-bearing area of the knee joint.
This sample is sent to a specialized lab where chondrocytes (cartilage cells) are cultured and multiplied in a collagen matrix.
Second Surgery:
Approximately six weeks later, a second surgery is performed to implant the cultured chondrocytes into the damaged cartilage area.
To watch a surgery performed by Dr. Utku Erdem Özer, click the following link:Watch the Surgery
Conclusion
Knee cartilage injuries are a common issue, especially among active individuals, and can lead to severe consequences if left untreated. This article has detailed the causes, diagnosis methods, and treatment options for cartilage injuries.
Modern medical advancements offer various surgical techniques that repair damaged cartilage tissue and improve patients' quality of life. However, every patient is unique, and determining the most suitable treatment requires a careful evaluation of the individual case.
Op. Dr. Utku Erdem Özer is highly experienced in the diagnosis and treatment of knee cartilage injuries. If you are experiencing cartilage problems, feel free to contact Op. Dr. Utku Erdem Özer: Whatsapp Contact
