Knee Arthroscopy

Introduction

Regarding knee arthroscopy, this information is designed to explain what is involved in an arthroscopy, the reasons why an arthroscopy may be required and what to expect on the day of surgery and after.

What is an arthroscopy?

'Arthro' means joint and 'scope' is to look at therefore a knee arthroscopy allows the surgeon to view inside your knee and directly inspect the bone and structures within. This gives a much more accurate picture than any other investigation such as x-ray or MRI.

Arthroscopy is commonly known as 'key hole surgery' as the incisions are minimal and therefore reduce scarring and allow quicker recovery. Prior to the advent of the arthroscope, such operations would mean a full open operation with extensive scarring etc.

During an arthroscopy a small camera-type device is inserted into the knee and this relays pictures to a television screen. At the same time instruments can be inserted into the knee so that surgery can be performed e.g. removing a portion of meniscus ("cartilage").

Reasons for arthroscopy

There are many reasons for an arthroscopy. Listed below are the most common reasons.

1. To resect (trim) or repair a torn meniscus (cartilage). The menisci are 2 semi - circular structures of soft fibrocartilage which act as shock absorbers within the joint. They are often injured by twisting activities. If you have a tear in the meniscus the torn section is resected - 'trimmed' back to healthy stable meniscus. Occasionally it is possible in some circumstances to repair the torn cartilage, although this is most common in the young adult or child.

2. Arthroscopy allows a clear view and physical inspection of the cruciate ligaments. The cruciate ligaments are 2 strong ligaments, the anterior and the posterior, which provide stability of the knee on twisting and pivoting activities. They are often injured in contact sports and skiing. The cruciate ligaments do not have the ability to repair themselves and it may be necessary to operate at a later date to reconstruct them.

3. Often through trauma or degenerative changes (osteoarthritis) small fragments of bone or articular cartilage can become loose within the knee joint. These can be removed and 'washed out' of the joint.

4. The smooth articular cartilage lining of the bone which allows smooth movement can be damaged when the knee is injured. This may result in a 'divot' of cartilage becoming loose and causing pain and locking of the joint. Via an arthroscopy the extent of the damage can be assessed and procedures carried out. The lesion can be shaved or a procedure known as micro - fracture performed where small 'pricks' are made in the bone to stimulate healing from the deeper levels. If the lesion is too large for this further surgery can be planned from the arthroscopy findings.

5. If the joint lining is particularly inflamed then a small area of this lining (biopsy) can be taken and sent for further investigations as to the cause.

6. The kneecap (patella) can be a source of pain in the knee. The arthroscope allows inspection of the under surface of the patella. If there is any loose articular cartilage this can be shaved. Another procedure called a 'lateral release' can be performed. This is the surgical division of the soft tissues on the outer aspect of the patella. These structures can be extremely tight causing the patella to track in the wrong position. This tightness over a long time can place excess pressure on the under surface of the patella resulting in pain.

Lateral release

These are the most common reasons to have an arthroscopy. There are other reasons and your Consultant will explain these to you if necessary.

Surgical procedure

A knee arthroscopy is almost always performed under a general anaesthetic. This can normally be done as a day case procedure, although on some occasions you may be advised to remain in hospital on the night of the surgery.

In most arthroscopies, two small incisions are made at the front of the knee. One incision is to insert the arthroscope and the other to insert the instruments required during the procedure. In some cases additional incisions are necessary. Fluid is inserted through the arthroscope so that the knee is inflated and easily visualised. A small puncture wound is made on the side of the knee to allow this fluid to escape from the joint.

Most arthroscopies take between 30 - 60 minutes to perform. At the end of the operation, the fluid is drained from the knee. Stitches are not usually required to close the wounds; steristrips, a type of sticky tape, temporarily hold the wounds closed. Local anaesthetic and morphine are injected into the knee to minimise discomfort after surgery. A relatively tight bandage is then applied.

With modern anaesthetic techniques, most patients usually wake relatively quickly and are aware of their surroundings within one hour of the end of the procedure.

What can you expect after your arthroscopy?

Unless advised to the contrary, you may place weight upon your knee immediately after surgery (although on the first time please do this under the supervision of a nurse or physiotherapist). You may go home once you are safely walking and you do not normally require crutches. As a general anaesthetic has been given, you must not drive for 24 hours after surgery, and should not be alone for that period. The nurses on the ward will advise you further on this if necessary.

It is normal for the knee to feel a little uncomfortable on the day after your operation. This is because the local anaesthetic inserted into the knee at the end of the operation may have started to wear off. Pain-relieving tablets may be required for a few days. These will be given to you on discharge from hospital.

Depending on the extent of the surgery performed, the tubigrip should be left on for 4-10 days. The knee should be kept dry whilst the tubigrip is on.

You may consider driving again after approximately 3-4 days. However, do NOT drive unless you are happy that you are safe. It may be in your interests to inform your motoring insurance company that you are resuming driving after your operation.
You will normally be seen in the out-patient clinic 4-10 days after surgery. At this appointment, the tubigrip will be removed. The operation performed will be explained to you again as you may not recall all you were told on the day of the surgery because of the anaesthetic! A period of out-patient physiotherapy may be necessary to help you return to full function and sports.

You will be told how much activity the knee can tolerate after surgery. This varies from patient to patient, but in most cases strenuous activity should be avoided for one month. If activity is resumed too early, the knee can swell somewhat and be painful.

It is vital to realise that although arthroscopy is 'key hole surgery", it is still a significant procedure. It is normal for the knee to swell for 2-3 months after the operation and for the knee to feel a little unstable until the muscles are fully developed again. You may experience an ache at the front of the knee at the site of the incisions for 2-3 months.

An arthroscopy is only recommended if it is thought that it will improve your symptoms and may help plan further surgery. However, it may not be possible for all your symptoms to improve, especially in degenerative ("wear and tear") conditions.

What can go wrong after an arthroscopy?

There is no surgical procedure in existence that is without possible complications! Arthroscopy can result in a number of complications. However, these are infrequent and the procedure is one of the safest operations in Orthopaedic Surgery.

Complications include:

1. Bleeding after the operation.
2. Swelling of the knee - some swelling is inevitable after the operation
3. Venous thrombosis ("clots in the veins"). Every attempt is made to minimise this complication. We do not routinely administer heparin. Unless the procedure is an emergency, patients should not be taking the oral contraceptive pill for six weeks prior to surgery. Finish your current packet and take other contraceptive precautions until after the operation. It is also advisable not to take hormone replacement therapy (HRT) at the time of surgery. Please ask for advice if necessary.
4. Infection - a rare but serious complication.
5. Following a lateral release of the patella it is quite common to be bruised on the outer aspect of the thigh and calf as soft tissue and muscle is cut.

Please contact the hospital at which you underwent surgery if you are at all concerned that there is a problem. In particular, act immediately if you develop a fever, severe pain or significant wound problems.

If you have any further questions or queries, please do not hesitate to contact your consultant.

Conclusion

We hope that this guide has been of use to you. You will have been recommended surgery only if the potential benefits of the operation outweigh the risks. If you have any questions relating to this please ask your Consultant.