Knee cartilage injuries

Cartilage and meniscal injuries to the knee are extremely common and so we approached Mr Stephen Guy who is a full time NHS orthopaedic consultant with a specialist interest in sports knee injuries and is clinical lead for Trauma in his Teaching Trust to explain all about them for you. Mr Guy works privately in Leeds and Bradford (as well as his NHS commitments) and treats all levels of athlete from amateurs to elite, professional athletes. He is a Fellow of the Royal College of Surgeons of England, has a diploma in Sports and Exercise Medicine and has research interests with different research groups, currently supervising MSc and PhD students. He is an expert in treating a wide array of soft tissue knee injuries.

What are the cartilage or menisci in the knee?

The meniscus is a ‘C’ shaped piece of cartilage that sits between the femur (thigh bone) and the tibia (shin bone). It has numerous roles but it is easy to think of it as a large shock-absorber that protects the knee. It cushions specifically the smooth gliding surface of the knee – the articular cartilage. Thus when the meniscus is damaged, the forces going through that part of the knee can increase massively, and over time lead to articular cartilage damage. Damaged articular cartilage in a knee leads to early osteoarthritis.

There are two menisci in the knee. One on the inside (medial side – where your knees touch one another) and one on the outer side (lateral side). In younger patients the menisci can tear due to a twisting injury during sporting activity and in older people may be a degenerate tear sustained from something trivial such as squatting down. Loss of meniscal cartilage leads to early degeneration and osteoarthritis (‘wear and tear’) of the knee. The relationship between meniscal tears and osteoarthritis has been studied for many years and is irreversible.

Signs and symptoms

Pain in the knee tends to be localised to the side of meniscal tear. A popping or tearing sensation may be felt at the time of injury in younger athletes. The knee can swell significantly and once settled patients can feel clicking or pain on certain manoeuvres such as squatting or twisting. In older patients the meniscus is a bit stiffer and so degenerate tears might occur with little or no injury being recalled. If the meniscal tears are sufficiently large then they can flip into the central part of the knee and stop it from getting fully straight. This is termed a ‘locked knee’ and needs urgent referral and surgical attention.

Diagnosis

As with all acute knee injuries an urgent review with a health care professional skilled in managing acute knee injuries is essential. Some knee injuries are very time-sensitive and may indeed need surgery urgently and some within a few weeks. An urgent clinical review will clarify the need for the correct imaging of the knee. The vast majority of injuries to the meniscal tissues can be diagnosed on an MRI (Magnetic Resonance Imaging) scan. It goes without saying that other knee injuries may be picked up at the same time as the meniscal tear on the MRI that will also need treating.

Treatment

Initial treatment involves first aid for the knee. Physiotherapy will always be recommended at this stage to aid with early rehabilitation and to reactivate your core and quadriceps. If you have a ‘locked knee’ then you will be recommended early urgent surgery. A locked knee can be caused by meniscal tissue getting trapped in the wrong part of the knee. In a locked knee, your knee will not fully straighten but may well bend really well. The surgery is done via key hole surgery (arthroscopy) and the meniscus tear will be assessed as to whether it needs to be trimmed or whether it has suitability for a meniscal repair. Picking a surgeon who is skilled and performs many meniscal repairs therefore is crucial. 

Meniscal repair

A repair of a meniscus is a highly skilled procedure that needs a knee-specialist to perform ideally within a few weeks of injury. The repair utilises keyhole techniques to stitch the meniscus back to where it has torn from. Not all tears are sadly repairable and various factors such as the type and size of tear, age, time since tear and other structures injured help the surgeon to decide. The chance of a tear healing are in the range of  70-80% with a higher chance of healing taking place at the same time as anterior cruciate ligament (ACL) reconstruction. 

Meniscal root repair

This is a catastrophic knee injury that was first described over 20 years ago and only recently has it become more publicised. The term root refers to the ends of the meniscus where they are anchored down or rooted to the bone. Once the root has gone, the ability of the meniscus to absorb shock is removed fully, particularly on the medial (inside) side of the knee. The forces transmitted then in this part of the knee exceed a healthy threshold for the articular cartilage and you will end up with rapid joint failure. Repair of this is more involving than a routine tear and involves drilling a small tunnel from the front to the back of the knee to anchor the free flapping edge of the meniscus back down to bone. Not all root tears are amenable to repair and the decision is based on many factors such as timing since injury, age, body mass index and the presence of existing wear and tear in the knee.

Meniscal ‘ramp’ repair

This is a special type of meniscal tear that occurs at the same time as an anterior cruciate ligament (ACL) injury. The presence of a tear behind the meniscus (posterior horn) where it attaches to the lining of the back of the knee (posterior capsule) is termed a RAMP tear. We know that this RAMP tear significantly destabilises the knee and so repairing the lining of the knee back to the meniscus will improve stability of the knee. Repair of this structure involves placing an extra incision (portal) towards the back of the knee so the surgeon can get access to place stitches across the tear. Not all RAMP tears are seen on an MRI and so it is essential that your surgeon is skilled at diagnosing these injuries and prepared to repair them at the same time as your ACL injury.

Conclusion

To find out whether we think your knee issue is likely to be a cartilage injury or whether we think you have suffered a ligamentous injury which may predispose you to a complex cartilage injury, and therefore whether a top surgeon like Mr Guy can help, simply fill in your clinical details for free on our online form so we can help get you on the road to recovery.