Arthroscopic (Keyhole) Knee surgery for damaged cartilage and meniscus tissue
Arthroscopic Meniscus Repair
Arthroscopic Meniscus Repair (AMR) is a keyhole surgical procedure through small 1cm incisions. Its aim is to achieve healing of meniscal tissue which has torn and is carried out to reduce pain and slow degeneration (wear and tear) of the knee joint.
To understand why AMR needs to be performed, it is first necessary to understand the anatomy and damage that takes place.
The menisci are two C shaped pieces of fibrocartilage that line your knee joint, providing cushioning and stability between the femur (thigh bone) and tibia (shin bone). They increase the contact area between the two bones and hence reduce abnormal stress forces during knee motion.
The medial meniscus is more commonly injured and is located on the inner aspect of your knee, while the lateral meniscus is located at the outer aspect of the knee.
Either or both menisci can be torn during activities that put excess pressure, twisting and bending forces on the knee joint such as football, netball, tennis and skiing.
Older patients are more likely to tear their meniscus with less strenuous activity as meniscal tissue degenerates with age making it weaker and less pliable.
The benefits of undergoing AMR include reduced pain levels, cessation of any unwanted mechanical symptoms from the knee such as locking or giving way and slowing down future osteoarthritis and degeneration to the joint.
The risk of complication is present with every surgical procedure but is very rare with AMR at around 0.1 – 1%, the most common being infection and deep vein thrombosis and/or pulmonary embolism.
The procedure is normally performed under general anaesthetic, and usually takes between 20 minutes to 1 hour. When you wake up, you should not be in too much discomfort as local anaesthetic is injected into the knee before the procedure ends, and effective painkillers are prescribed for you to take at home for the first 2-5 days if required.
Patients are allowed to walk the same day and return home, normally with crutches for comfort, bandaging over the knee and sometimes a special knee support (knee brace) to wear for a few weeks.
At home you should keep your leg elevated when resting, with an ice pack placed on the knee for one or two days to help reduce any swelling and continue with the gentle exercise protocol your physiotherapist and surgeon have advised.
This is important to prevent the knee from getting stiff and also helps build up your thigh (quadriceps, hamstrings) and calf muscles (gastrocnemius, soleus) for a speedy recovery.
What is Arthroscopic Meniscus Repair (AMR) ?
Arthroscopic Meniscus Repair (AMR) involves repairing the torn meniscus using an arthroscope and other surgical tools. An arthroscope is a thin, fibreoptic high definition camera with a similar diameter to a drinking straw. The miniature camera is attached to a monitor similar to a TV screen that allows the surgeon to see the inside of the knee without needing to make a large incision.
Because the arthroscope is inserted into the knee joint through a small 1cm incision (portal), it has certain advantages when compared to open surgery through larger incisions including:
less pain after the operation, lower risk of infection, reduced hospitalisation time, quicker recovery and return to function
The procedure can be split into two types:
2)partial meniscectomy (removal of some of the damaged meniscus)
Why is AMR performed?
Surgery is not always necessary for a meniscus tear. Non operative treatment in the form of physiotherapy should always be pursued as a first line option.
The decision to treat the meniscus tear surgically depends on the frequency of your unwanted symptoms, which include focal pain and tenderness over the knee, locking (where you are unable to straighten your knee), a feeling of instability (knee giving way), and difficulty kneeling, squatting or twisting and turning.
The decision to repair the meniscus versus remove the damaged part depends on the type of meniscus tear and the location of the tear within the meniscus.
Only the peripheral part of the meniscus has a good blood supply, and as blood is required for healing, generally these peripheral tears respond best to repair with stitches.
Patient factors such as younger age ( <40 years old), no arthritis in the joint, those of a healthy weight (BMI<30) and those willing to engage in pre and post-operative physiotherapy also have a higher rate of success with AMR.
Importantly, the overarching principle of arthroscopic meniscus surgery is that as much functioning meniscus should be kept as possible, this is why at all time , where possible it is in the best interests of the patient to repair viable torn meniscus.
If performed successfully, AMR will preserve as much of the meniscus as possible, which slows joint degeneration, increase knee stability during complex activities and exercise and can significantly reduce pain.
The alternative to AMR is known as Arthroscopic Partial Meniscectomy (APM)and is the more frequently performed surgery in the treatment of Meniscal tears.
It means removal of the torn piece of meniscus and is performed in all cases where the meniscus cannot be repaired for technical reasons or because the torn piece has no viable blood supply and repairing it would lead to inevitable failure and re-tear in the weeks following surgery.
APM is also more widely performed by orthopaedic surgeons as it was traditionally the only method of surgically treating meniscal tears and is technically easier to perform.
It is important you are treated by a surgeon who is comfortable and experienced in all the available treatment options so the correct one is chosen for you.
Arthroscopic Meniscus Repair, The Surgical Procedure
AMR can be performed either under general anaesthesia (asleep attached to a ventilator with a tube in your windpipe to help you breathe) or spinal anaesthesia, where local anaesthetic is injected close to the spine to numb you from the waist down for about 3 hours.
Additionally, local anaesthetic is injected into the incision sites and the knee joint cavity at the end of the procedure to help ease any post-operative discomfort.
Current literature shows that spinal anaesthesia has some evidence for improved mortality and morbidity (less complications) when compared with general anaesthesia, in particular for longer orthopaedic operations such as hip and knee replacement surgery, or surgery to fix broken hip bones.
During the surgery, local anaesthetic such as bupivacaine will minimise the pain you experience. As AMR involves soft tissue surgery, it is moderately painful. To reduce pain post-operatively, oral low dose opioids such as codeine phosphate and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen are sometimes prescribed for a few days and can be taken as required. It is important to try and avoid opioids if possible and certainly not take them regularly for more than 1 week as they are addictive and have unwanted side effects such as constipation and nausea.
Will I need to do any preparation?
Pre assessment clinic and checks
You will be booked in to attend a pre-assessment clinic prior to your surgery. The aim of the appointment is to assess your general health and assess how safe it is for you to have the surgery and anaesthetic. You will be asked about any medication and supplements you may be taking, as some of these may increase your chance of bleeding or affect the anaesthesia. Warfarin and Rivaroxaban are examples of blood thinners which your doctor will advise you to stop taking prior to the surgery.
A bespoke after care plan will also be made to ensure that you are well prepared to get home safely and be able to cope following the surgery.
The surgical team and your consultant will explain the risks and benefits associated with AMR surgery, after which point you will be asked to sign a consent form for the surgery to go ahead. You should be given adequate time to rethink your decision before the date of the surgery should you wish to ask any more questions or change your mind.
The day of surgery
On the day of surgery, you will need to have fasted for 6 hours minimum (no food or drink).
You will be met by your surgeon and anaesthetist who will go over any other questions you might have, and they will mark the site of the surgery with a marker pen. You will get into a hospital gown and be admitted by one of the nurses or health care assistants.
You will be escorted to the operating theatres on foot or a trolley, initially to the anaesthetic room. Once you enter the anaesthetic room, the anaesthetic doctor and a healthcare professional called an operating department practitioner (ODP) who assists the anaesthetist will begin the process of general anaesthetic. This begins with the placement of a small plastic tube into the vein in the back of your hand so they can inject the anaesthetic medicine which puts you into a deep sleep. They will then place a larger breathing tube (ET tube) into your windpipe just past your vocal cords carefully and attach it to a ventilator which helps regulate and monitor your breathing during the surgery.
Inside the operating theatre
You will then be wheeled into the operating theatre to be positioned face up on the operating table, lying on your back. A tourniquet cuff may or may not be attached to your thigh to limit blood flow to the knee, depending on the surgeon’s preference. Further, the knee to be operated on will be thoroughly cleaned with antiseptic to prevent infection and sterile surgical drapes will then be placed onto that knee, exposing the cleaned surgical site, by the surgeon and theatre nurse who are wearing sterile gloves and theatre gowns.
The surgeon will then carefully make two small 1cm incisions, called ‘portals’, on your knee, in the locations shown on the image below. The knee joint will then be filled with a sterile saline solution to clear gently create some space in the knee between the tibia and femur bone for the instruments and constantly flush the knee off any debris or blood.
This will also make the image produced by the arthroscope clearer. The precise placement of these portals is important, as the joint space is quite narrow, so accidental damage to the meniscus or cartilage of the joint can potentially occur and ideally the second portal should be made under direct vision via the arthroscope which is placed in the knee through the first portal.
Once the arthroscope has been inserted through the portals into the knee joint space, structures in the knee are thoroughly and systematically examined to inspect for further damage. These structures include the anterior and posterior cruciate ligament, articular cartilage, Hoffa’s fat pad, synovial plicae and both the medial and lateral menisci.
The meniscus tear is then identified and probed to assess the size, location, stability, tissue quality and pattern of the tear. At this stage, the decision is made whether to repair or remove the damaged meniscus tissue. If the meniscus is red and vascular as opposed to white and avascular it should be amenable to repair.
The two sides of the torn meniscus tissue are then prepared for healing by using a small motorised shaver or even a long thin needle to pierce the fragments and promote bleeding.
If the blood supply to the meniscus is damaged, several techniques are available to improve it. These have variable scientific evidence to support them but include placing a blood clot between the tear itself, creating small blood vessels around the edges of the meniscus or causing a controlled bleed in the joint lining.
To complete the procedure, the meniscus is sewn into place using various types of suture devices.
There are a number of different described techniques to repair a meniscus and they are named according to the direction of travel of the specialised arthroscopic needles.
The most common currently is the all inside technique using hybrid systems of sutures attached to small tags which sit behind the meniscus. The all inside technique is best for tears of the posterior part of the meniscus at the back of the knee. The outside in technique is best for anterior tears at the front of the meniscus, whilst the inside out technique is less common now as it is technically demanding and requires more incisions.
Once the repair is performed and the fixation deemed solid, the surgical tools are removed from the knee and the small portals are closed with suture or paper stitches or skin glue according to your surgeon’s preference.
Waterproof dressings are then placed over the knee and a compression bandage for 12-24 hours to help reduce any swelling.
The patient must keep the knee dry for 2 weeks till your follow up appointment with your surgeon where the skin incisions will be checked to ensure they have healed, and any stitches removed.
If a meniscal repair is performed, you will need to wear a special hinged knee brace when walking for 6 weeks. This prevents excessive knee bend while the meniscus is trying to heal and limits the risk of failure of the repair.
If the torn meniscus is removed, you will not need a knee brace.
Post-operative surgery care after your procedure
Rehabilitation post-operatively aims to reduce swelling, improve range of movement and strengthen the quadriceps (thigh) muscles. You will be seen by a physiotherapist before and ideally after your discharge from the hospital. The physiotherapist will show you exercises designed to strengthen your knee and prevent it from becoming stiff.
These exercises should be performed immediately to improve range of motion and strength in the leg muscles. You may begin practising standing on one leg once pain and swelling has subsided. To help ease into improving your balance, you may start by using the wall as a support, and then gradually transition to standing on one leg unassisted.
You will be provided with crutches and taught how to use them by the physiotherapist, with full weightbearing allowed as you can tolerate.
You should return your crutches to the physiotherapy department or to your surgeon in a follow up appointment once you no longer need them.
If you experience persistent pain, swelling, oozing from the wound, fever or calf pain, it is essential that you contact your GP immediately or attend the Urgent Care Centre or Emergency Department linked to the hospital your surgeon works in or where the operation was performed for evaluation.
Painful cartilage tears on the undersurface of the knee cap causing catching and pain at the front of the knee
Smooth cartilage surfaces after keyhole coblation therapy 5 minutes later
Risks of arthroscopic meniscal repair surgery
The majority of the major nerves run behind the knee, and as AMR is usually performed from the front of the knee these vital nerves are relatively safe. However, the common peroneal nerve runs around the outer (lateral) side of the knee joint and supplies the muscles of the front and side of the shin. If this nerve were to be damaged during the AMR procedure, the result would be a condition known as ‘foot drop’. Foot drop is characterised by slapping of the foot onto the ground, difficulty raising the foot and as a result a high stepping gait.
The saphenous nerve can also be injured by one of the skin portals and can result in a temporary or permanent numb patch over the knee which though feels odd to the touch, will not stop you leading a normal life.
Advances in meniscus repair technique have led to nerve complication rates falling from 9% to about 1%.
Arthrofibrosis is defined as a build-up of scar tissue around a joint following traumatic injury or surgery. It can result in limited range of motion in that joint and substantial pain. The management options for arthrofibrosis include pain management using over the counter medications, physiotherapy and in some cases surgery to remove the excess scar tissue. There is currently no data on the percentage risk of arthrofibrosis following arthroscopic meniscus repair as it is very rare.
Infection risk ranges between 0.23-1% of patients following arthroscopic meniscus repair. Although this is a low rate, if a deep infection were to arise the consequences could be life and limb threatening. It is therefore essential to regularly see how your wound is healing and call your GP or attend your local Emergency Department (ED) if any oozing, pain, redness or fevers associated with infection occurs.
The risk of developing a Deep Vein Thrombosis (blood clot in the deep vein of the leg) is around 1%.
A DVT usually manifests as pain and swelling in your calf muscle, made worse by stretching the muscle. This is a serious condition as a small piece of the blood clot can break off and travel to your lungs and get lodged there, this is called a pulmonary embolism, which is a potentially fatal condition. A pulmonary embolus normally causes severe and sudden unrelenting chest pain so if you have these symptoms you need to be seen urgently by a medical doctor in the ED or call an ambulance if in doubt.
Q)How long does it take to recover from torn meniscus surgery?
A)Home and walking the same day, but 2 weeks to feel comfortable after APM and 6 weeks for AMR as you have to wear a hinge knee brace.
Q)How long after meniscus surgery can I walk?
A)You can walk immediately using 2 crutches for comfort for 1 week.
Q)How long will my knee hurt after arthroscopic surgery?
A)You should feel minimal pain when you wake up due to the local anaesthetic but there will be some discomfort which is to be expected for the first 3-7 days depending on the complexity of the surgery and how you perceive pain as all patients are different.
Q)When can I start playing sports again?
A)Return to sport after APM is4-6 weeks and after AMR is 10-12 weeks depending on your pre surgery level of fitness and strength and how hard you work with your physiotherapist after surgery.
Q)When can I return to work?
A)This depends on your occupation but normally you can work from home after 48 hours if you wish, return to an office job and commute after 2 weeks and return to an active or physical job after 6 weeks in most cases.