The cartilage in your knee joint is a bit like a car’s shock absorbers, as it acts as a cushion that allows the bones in the joint to move without causing too much friction – but cartilage damage compromises that function, which could lead to serious conditions developing. Learn about damage to cartilage and how we treat it at Sports Med London below.
Cartilage – A Specialised Tissue
The cartilage in your knees is known as articular cartilage. The tissue is shiny white and smooth, and it is found on the ends of the thighbone and shinbone, as well as underneath the kneecap.
Cartilage does not receive a direct blood supply. Instead, it is fed by the fluid in the joint. Unlike other tissue, cartilage damage usually does not heal on its own.
How Cartilage Is Damaged
Cartilage damage can be caused by different factors. The most common causes include:
- Usual wear and tear of the body
- Falling on or twisting your knee
- Spontaneous degeneration along with the bone under it
When cartilage is damaged, the ends of the bone that it usually cushions rub together, which causes painful swelling. Your knee may also lock or give way from time to time.
Diagnosing Cartilage Damage
Your specialist will use various methods to diagnose cartilage damage. They will listen to you describe the symptoms you have experienced, and they will physically examine your knee. They will also give you an MRI scan if they need to find out the location and size of the damage.
Treatment At Sports Med London
We provide various surgical treatments for cartilage damage at Sports Med London, including:
Arthroscopic Abrasion – Also known as Radiofrequency Chondroplasty. The surgeon inserts a high-speed shaver or a radiofrequency probe through small incisions and uses the tool to smooth the surface by removing bits of damaged cartilage.
Microfracture Surgery – Also known as Pick Chondroplasty. The surgeon inserts a pick with tiny tips through small incisions and uses it to make many small holes that form tiny channels between the surface of the cartilage and the bone underneath it, causing bleeding and stimulating healing.
Subchondral Drilling – The surgeon uses a tiny drill to produce the same effect as microfracture surgery.
Autologous Chondrocyte Implantation (ACI) – The surgeon removes healthy cartilage cells via a small incision and cultures them in a lab. In a second surgical procedure later, they implant the cultured cells in the damaged area and cover them with a collagen membrane.
Bioabsorbable Matrix/Scaffold – A matrix or scaffold is attached to the area of cartilage damage after it has been prepared by microfracture surgery or subchondral drilling.
No matter the treatment you have, you will need to use crutches and a knee brace for some time afterwards. You will also receive physiotherapy.
Keep reading for more information about cartilage damage.
What is articular cartilage?
Articular Cartilage is the smooth shiny white tissue lining the end of bones where these bones connect to form joints. It ranges from a millimetre in thickness to several millimetres thick depending on the on the load across the joint. It acts as a cushioning material and allows the ends of the femur (thighbone), tibia (shinbone) and patella (kneecap) to move freely with minimal friction. It is a highly specialised tissue and does not receive a direct blood supply thereby relying on the synovial fluid (joint fluid) to receive its nutrition and oxygen. As a result, if damaged or worn, it tends not to heal on its own.
What causes damage to articular cartilage?
Articular cartilage can degenerate with increasing age, wear and tear, or trauma such as a fall or twist. Occasionally it may degenerate with its underlying bone spontaneously. This results in the joints rubbing during movement and a lack of cushioning with weight causing pain, inflammation and swelling. Pain may be localised, and patients may also complain of the knee catching with occasional giving way and locking.
How is articular cartilage damage diagnosed?
The diagnosis is made according to symptoms, mechanism of injury if applicable and a physical examination. An MRI scan is particularly accurate in quantifying the size and depth and location of the articular cartilage lesion.
How is articular cartilage damage treated or repaired?
Cartilage repair refers to surgical procedures where orthopaedic surgeons stimulate the growth of new cartilage to restore normal or near normal function. Degenerate conditions can be delayed or potentially prevented with this type of procedure. The aim of cartilage replacement therapies is to stimulate growth of new ‘hyaline-like’ cartilage. Various arthroscopic procedures which can have an active role in cartilage replacement include:
Arthroscopic Abrasion or Radiofrequency Chondroplasty. This involves the use of a high speed shaver or a special radiofrequency probe to either shave damaged and frayed articular cartilage flaps or superheat them to produce a smooth stable surface.
Microfracture surgery (pick chondroplasty) uses fine tipped picks to make multiple small “pepperpot” holes that breach the subchondral plate and produce channels between the deeper underlying bone and the articular surface. This is a form of a marrow stimulation technique and induces bleeding and therefore a healing response. This generates a fibrocartilage cap over the defect.
Subchondral Drilling uses a very narrow drill to achieve the same as microfracture. It allows for deeper penetration into the bone to produce a fibrocartilage cap.
Autologous Chondrocyte Implantation (ACI) In this method, healthy cartilage cells are removed using an arthroscopic technique and are cultured in a laboratory. Cultured cells can then be implanted in the damaged area with an open surgical technique involving a second surgical procedure. The cells are covered with a collagen matrix/membrane. If the cultured cells are impregnated into the matrix before application to the chondral (articular cartilage) defect this is referred to as MACI (Matrix Autologous Chondrocyte Implantation).
Bioabsorbable Matrix/Scaffold. These are scaffold or matrices that are applied to the cartilage defect often after preparation of the lesion with a marrow stimulation technique such as subchondral drilling or microfracture. The matrix is then applied often after mixing with aspirate (fluid taken) from the bone marrow or PRP (Platelet Rich Plasma) and fixed to cover the defect with an absorbable fibrin glue as a sealant. The matrix then captures and contains the mesenchymal cells (often referred to as Stem or Stromal Cells) from the bone marrow to remain in the defect and mature into new cartilage tissue.
Recovery from any of these procedures requires a period of time non-weight bearing, mobilising with crutches and wearing a range of motion knee brace before progressing onto a full course of physiotherapy rehabilitation.