What is it?
The knee joint has 2 types of cartilage within it. The smooth articular, or hyaline cartilage, lines the ends of the bones and the firm fibrous type cartilage, known as menisci, act as shock absorbers between the bones. As the smooth articular cartilage wears away with time, the knee joint develops osteoarthritis leading to pain, swelling and deformity. Eventually if all the cartilage is worn away a knee replacement may be required. Cartilage preservation refers to a variety of procedures that can be used to reduce the loss of articular cartilage over time or replace areas of damaged cartilage in an attempt to improve symptoms and avoid the need for knee replacement surgery. The type of cartilage preservation surgery is dependent upon the location, pattern and severity of cartilage damage. It may also be performed in conjunction with other procedures such as ligament reconstructions, meniscal repairs and osteotomies in order to improve the longevity of the cartilage preservation surgery.
- Microfracture: this is a procedure whereby small potholes or defects within the articular cartilage can be filled in by encouraging the body to regrow new cartilage.This is normally performed arthroscopically and tiny drill holes are placed into the bone at the base of the articular cartilage defect to encourage bleeding into the pothole and a fibrocartilage cap to form over the underlying bone.This is suitable for isolated smaller defects with defined edges.
- Osteochondral autografts or mosaicplasty: for larger defects within the weight bearing portions of the knee it may be appropriate to take small cores of bone with a cartilage covering from non-weight bearing aspects of your knee and transport them into the area where the defect has been found.The benefits of this are creating a solid smooth new surface to the weight bearing part of the joint thus reducing symptoms during activity.
- Osteochondral allografts or BioUni surgery: if full thickness cartilage defects are identified within your knee in the weight bearing portions and these are of a shape or size meaning that donor site grafts cannot be taken from another part of your own knee, it may be possible to perform an osteochondral allograft or transplantation.This involves matching a segment of articular cartilage and underlying bone from a cadaveric donor to the shape and size of the defect within your knee and transplanting an appropriately extracted osteochondral graft in order to re-surface your joint in a biological fashion.
- ACI/MACI: or autologous chondrocyte implantation is a procedure whereby cartilage cells are harvested from your knee and sent to a special laboratory where the cells are grown in a medium or on a matrix to then be later transplanted back into your knee to fill out the defect in the hyaline cartilage.In certain circumstances and situations this has been shown to be effective.It is only carried out in a small number of specialist centres throughout the UK.Please feel free to ask your treating surgeon whether or not you would be suitable for this procedure.
Why would I need cartilage preservation surgery?
Cartilage preservation surgery is useful for patients with isolated or small full thickness articular cartilage defects and a relatively normal knee other than this. The benefit of cartilage preservation surgery over partial or total knee replacement is that it avoids losing good bone and cartilage stock that may be present and is likely to last longer if successful than a replacement procedure. It is therefore particularly attractive in younger patients with articular cartilage problems.
What happens after surgery?
The procedure is normally carried out through either an arthroscopic or small open approach dependent on the type of defect and surgery. It will either be done as a day case or an overnight stay and the immediate and medium term post-operative rehabilitation is very variable dependent on the type of surgery you have had. It may be post-surgery that it is necessary to restrict your weight bearing or your range of movement in a knee brace in order to protect the cartilage that has been restored. We work with a number of expert physiotherapy teams in order to ensure the optimum recovery and outcome following this complex surgery.
Weeks 0 – 2
Over the first couple of weeks it is important to rest the knee and get the swelling and bruising to subside and gradually work on your range of movement within the parameters set by your surgeon dependent upon the type of surgery you have had.
Weeks 2 – 12
Physiotherapy services will guide you over this period of time. The exact milestones will be very variable depending on the type of surgery. Please discuss your post-operative recovery with your treating surgeon.
Frequently asked questions
- How long will I be in hospital?
The average length of stay is between 1-2 nights for the majority of cartilage preservation procedures.
- When can I return to work?
This is highly dependent upon the type of surgery you have had. Please discuss it with your treating surgeon.
- How will I know if cartilage transplantation or preservation is appropriate for me?
Your treating surgeon will examine your knee and carry out a number of investigations normally including an MRI scan. This will generally give us a good idea of the pattern and severity of articular cartilage damage to your knee. Occasionally an arthroscopy may be performed to fully inspect the knee joint under direct vision. Following information gathering it will be apparent to your surgeon whether or not cartilage preservation surgery may benefit you or whether it is more likely you will require a non-operative approach or potentially a knee replacement.