Knee Arthroscopy

Indications: Trauma (including Meniscal injury, Chondral damage, Ligament rupture, joint line fractures) Osteoarthritis, Rheumatoid Arthritis

Patients are seen in this specific clinic approximately 2-3 weeks prior to surgery. Here they under a thorough assessment by both medical and nursing staff. This includes simple blood and urine tests as well as the taking of swabs which identify patients carrying certain bacteria including MRSA. Mr Hartwright sees patients at this point in order to explain the nature of the surgery and possible risks, identify any possible problems, obtain the patient’s consent to surgery and, of course, to answer any outstanding questions the patient may have.

Patients normally receive a General Anaesthetic (GA).

If a patient is thought to have any anaesthetic risk factors which may cause problems during, or after surgery, they are seen in pre-assessment clinic or given an appointment to see an Anaesthetist well before the day of surgery.theanaestheticgroup

 

Once positioned on the operating table a tourniquet is applied and an Examination Under Anaesthesia (EUA) is performed. This allows a more thorough assessment of the knee than is possible in the clinic setting.

Mr Hartwright performs the operation through two small stab incisions (approximately 0.5cm) on either side of the knee (the so called anterolateral and antermedial ports). These allow him to pass the arthroscope and instruments into the knee joint.

Initially the knee is examined both by directly visualising and probing all parts of the joint: including the lining of the joint (synovium), the joint surfaces, menisci and ligaments. It is at this point that the diagnosis is made and a decision made regarding treatment.

 

The Menisci are rubbery, crescentic shaped pieces of fibrocartilage that lie on either side of the joint. They have a number of different functions including to act as shock absorbers to the knee. In twisting injuries, the menisci can be torn and subsequently cause symptoms eg locking, clicking, pain. There are several different types of tear (horizontal, radial, bucket-handle etc.). Treatment depends upon the pattern of the tear but tends to be either repair or excision of the affected part of the meniscus.

Meniscal repair involves roughening of the torn surfaces and suturing of the tear. This is all performed within the knee and so no further incisions are (usually) necessary. Only certain types of meniscal tear are amenable to this type of treatment and this is can only be assessed during the procedure. Post operatively, the repair needs to be protected and so a period of gentle rehabilitation and occasionally bracing is required.

Partial menisectomy: This is where the torn part of the meniscus is removed. As much of the normal meniscus is preserved in order to retain the functions of the tissue and decrease the potential for late Osteoarthritis.

 

The part of the bones that make up the knee joint i.e. those parts of the bone articulating with one another (femur, tibia and patella) are covered in a thin layer of specialised tissue called Hyaline (or articular) cartilage. This tissue facilitates the fluid movement of the joint. In certain conditions (e.g. Osteochondritis Dissecans, Chondromalacia) and trauma, this surface can be damaged. Treatment of this damage depends upon several factors but ranges from conservative management to Autologous Chondrocyte Implantation.

It is the articular cartilage that is significantly affected in Osteoarthritis (wear and tear arthritis). The cartilage becomes thin, losing it’s smooth surface and is eventually worn away completely exposing the underlying bone.

In any of the above conditions, if part of the articular cartilage (+/- an area of the attached bone) breaks off, this becomes a loose body. This can interfere with the normal function of the knee causing pain, locking and can sometimes actually be felt by the patient

 

Arthroscopy of the knee is a day-case procedure i.e. the patient can return home on the same day. It does require a general anaesthetic so patients are advised to have a friend/relative to collect them from hospital and to look after them for the first 12-24 hours.

 

Mr Hartwright encourages patients to start mobilising as soon as comfort allows. This is done under the supervision of either the physiotherapists or nursing staff. Most patients start to walk within an hour or so of the operation albeit with crutches surgery.

Patients are provided with instructions as to the exercises that they should perform once discharged. It is vital that they do these exercises in order to optimize the results of surgery.

Mr Hartwright uses steristrips to close the skin. These are covered by a simple dressing and the knee is bandaged with wool and crepe. The bandage can be removed at 48-72 hrs but the dressings should remain intact for 7-10 days post-operatively. This is normally performed by the patient’s district or practice nurse. The wounds should be kept dry for the same period of time.

Patients are allowed to drive as soon as they feel safe (and are able to perform emergency manoeuvres).

Patients normally require 2 weeks off work (depending upon their type of employment i.e. desk job or manual labour).

 

Potential Risks

There is a risk of infection with any surgical procedure. Infection in joint replacement surgery is particularly problematic as it can lead, ultimately, to the failure of the joint replacement. Mr Hartwright takes great care to ensure that the risks are put at a minimum.

Pre-operatively: Patients are pre-assessed so as to identify patients who are at greater risk of infection and measures are taken to decrease these risks e.g. Identifying and treating those patients who are MRSA carriers or who have urinary tract or other infections.

Patients are advised to take care of their skin pre-operatively; any cuts or scratches may allow bacteria to enter a patient’s system and consequently increase the risk of infection. 

During the anaesthetic, intravenous antibiotics are given in order to limit the potential effects of bacteria entering the surgical site.

All instruments are sterilised to strict guidelines.

Joint replacement surgery is performed in specially designed theatres (with air filters and laminar flow) so as to decrease the risk of airborne infection.

The surgical site is prepared using antibacterial solution with the aim of preventing the entry of bacteria from the patient’s own skin.

All theatre staff directly involved in the procedure thoroughly wash their hands and wear sterile gowns and gloves such that no unsterile object comes into contact with the patient. 

Patients are given two further doses of intravenous antibiotics whilst on the ward after surgery.

The surgical site is covered with a dressing so as to avoid infection from direct contact.

The rate of infection in patients undergoing joint replacement surgery is generally quoted as 1%. Link to RHCH infection rates.

Mr Hartwright’s rate of infection for joint replacement surgery is under 0.3% 

Post-operatively most patients are provided with Patient Controlled Analgesia (PCA). This is an intravenous delivery system which allows the patient to give themselves a fixed dose of a morphine based analgesia through the pressing of a button.

Patients are encouraged to inform either the nursing and medical staff if they are experiencing pain. There are many analgesic agents at our disposal and there is no longer any need for patients to suffer in discomfort. 

Following lower limb joint replacement surgery there is a risk of patients developing clots either in the deep veins of the legs (DVT) or in the lungs (Pulmonary Embolism – PE). The latter can be very serious, even fatal. Following surgery patients are given injections of a heparin based substance to prevent clot formation. They are also provided with compression stockings and mechanical foot pumps which encourage blood flow through the circulatory system. Most importantly, patients are encouraged to regain mobility as quickly as possible so as to prevent clot development. 

The new femoral head (the ball of the ball and socket joint) is smaller than the patient’s own and is therefore less stable/more likely to come out of the socket. As previously mentioned, patients are educated as to movements that should be avoided thus preventing dislocation (including bending down and twisting the hip). Nonetheless, dislocations can still occur.

The rate of dislocation varies but is generally quoted as occurring in 1-4% of patients undergoing joint replacement surgery.
None of Mr Hartwright’s patients have suffered with a dislocation of their hip replacement. 

When the new hip is implanted, the surgeon must assess the “tension” of the tissues. If the ball is very loose in the socket the hip is more likely to dislocate. If the ball is too tight in the socket, movements of the joint may be stiff. In an effort to establish the correct “tension”, it sometimes happens that the overall length of the leg is altered (normally the leg length is increased).

Usually, any difference in leg length is not noticed by the patient but if it is noticeable (normally a discrepancy of ?2cm) then a heal raise can be placed in the other shoe to offset this inequality. 

There are many other potential risks but the above probably represent the most important and certainly most asked about.