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Articular Cartilage Injuries

Articular cartilage is a tough layer that gives the ends of the bones a smooth shear-resistant bearing surface. Articular cartilage is also referred to as ‘hyaline’ cartilage.

The term chondral injury is often used for a defect that only involves the cartilage surface and osteochondral when it also involves the underlying bone. Chondromalacia is another term often used when articular cartilage becomes damaged.

Articular cartilage damage can range from acute traumatic defects with healthy surrounding cartilage to degenerative lesions seen after repeated trauma where surrounding cartilage is of less good quality and ultimately, at the other end of the spectrum, fully established knee osteoarthritis.

Symptoms & Diagnosis

You may experience activity-related pain and swelling. Mechanical symptoms such as catching and locking can occur especially if there are loose floating pieces of cartilage. Your knee may occasionally buckle or give way and you may hear crepitus on knee movements.

Clinical assessment may be supplemented with standing x-rays and a MRI scan. Sometimes, MRI scans may not reliably demonstrate articular cartilage defects and these are identified at knee arthroscopy. The mechanical alignment and stability of your knee is also assessed.

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Non-Operative Treatment

Articular cartilage lacks blood vessels, nerves and lymphatic tissue. Thus, it has a poor ability to self-repair post injury and treating cartilage injuries can be a challenge.

Treatment can depend on many factors including the location and size of the defect, your symptoms, limb alignment, stability and the presence of osteoarthritis.

Non-operative management can include physiotherapy-led rehabilitation, activity modification, injection treatments or an unloader brace.

Surgical Treatment Options

Chondroplasty may be performed to shave or smooth over a defect and stabilise the edges of the lesion.

An unstable osteochondral lesion or potentially fixable loose lesion may require early surgical fixation. Alternatively, loose bodies may need excision.

Marrow stimulation techniques include microfracture, which involves making small holes in the bone to allow stem cells from the bone to migrate through with the aim of healing the defect with a scar-type cartilage called fibrocartilage. Results can deteriorate over time, but microfracture has generally been the standard by which other cartilage procedures are compared.

Variations on the microfracture technique include nanofracture, where narrower and deeper instruments are used and AMIC (Autologous Matrix Induced Chondrogenesis) where a scaffold is applied to ‘trap’ the stem cells.

Other procedures include cell-based repair techniques such as a MACI which involves growing one’s own cells and implanting them, or using osteochondral grafts – either from your own knee, termed autologous, or donated allograft.

Cartilage restoration procedures may be supported by an osteotomy.

Partial knee replacement or total knee replacement may be required in older patients where there is significant osteoarthritis.

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