To reconstruct the posterior cruciate ligament (PCL), this website aims to give information on the PCL structure and function, of what an operation entails and post operative rehabilitation. After reading this website if you have any further questions please contact us.
Please be aware that this information sheet deals primarily with PCL reconstruction. The operation is commonly performed alongside reconstruction of other knee ligaments e.g. the posterolateral complex. The rehabilitation protocol in such a circumstance would differ from a "pure" PCL reconstruction. There are other information sheets relating to the posterolateral complex.
What is the Posterior Cruciate Ligament?
The cruciate ligaments are a pair of extremely strong, thick ligaments in the centre of the knee joint. There is an anterior cruciate ligament (ACL) and a posterior and they form a cross (this is where the name cruciate is derived). The PCL lies behind the ACL on the outer aspect at the back of the tibia and runs upwards and forwards to the inner aspect of the femur (thigh). The PCL is significantly stronger than the ACL.
Function of the Posterior Cruciate Ligament
The primary functions of the PCL are;
To prevent backwards movement of the tibia (shin) on femur (thigh)
To prevent hyperextension of the knee, bending backwards on itself
Stabilises the knee on rotational movements acting as a central axis of rotation
Posterior Cruciate Ligament Injury
The PCL is most commonly injured by a direct blow onto the front of the lower leg when the knee is in a flexed position. This is most often a fall onto the flexed knee, a tackle in contact sports or a dashboard injury in a car accident. The knee may give way if the PCL is damaged especially on descending stairs or walking down hill.
If the PCL is damaged it results in excessive movement backwards of the tibia on the femur. This causes the tibia to sit in a slightly subluxed backward position. As well as the problems with instability (giving way) this subluxation is known to lead to secondary problems with the under surface of the kneecap (patella) and the medial (inner) aspect of the knee joint, as there is increased load on these surfaces. Over time this may lead to early degenerative changes (osteoarthritis).
If the PCL is damaged in isolation it is often possible to function relatively normally without the need for reconstruction. However, if other ligaments are damaged, especially what is known as the posterolateral complex, this leads to additional rotational instability. If this "double damage" occurs it is usually not possible to function normally or participate in sports without significant instability and the resultant risk of further damage to the knee. If you have sustained other damage within the joint, such as to the meniscus or articular cartilage, it may lead to a less optimal outcome.
No matter how successful the operation, it is important to understand that surgery to reconstruct the PCL cannot give you a normal knee as it can never truly replicate the PCL that was previously present either anatomically and physiologically. However, surgical reconstruction can allow the knee to function relatively normally and a return to sports with no instability or risk of further damage to structures inside the knee, although the results of the surgery depend on damage to other structures within and around the knee as well.
An MRI (magnetic resonance imaging) scan is not essential to diagnose an acute PCL tear as an accurate and detailed history and clinical examination is more reliable. MRI can confirm the diagnosis and give additional information which may aid in planning intervention in certain circumstances e.g. in multiple injuries. On MRI the PCL appears as an uninterrupted curved dark band. If damaged there is disruption of this or complete absence. Although there is good correlation for diagnosis it is not 100% accurate and therefore diagnosis depends on a combination of history, clinical examination and the scan.
The PCL will not heal itself and it is not possible to repair a torn one. Therefore, an alternative tissue must be used to replace it (if there is a need for it to be replaced).
There are 3 main types of grafts available to replace the PCL;
- Using the patient's own tissues (autograft)
- Using another person's tissue (allograft)
- Using artificial material (largely discontinued)
There are two principal choices for the graft used to reconstruct the PCL. If possible, it is probably best to use the hamstring tendons from either the leg which is undergoing the surgery or alternatively the hamstrings from the other leg if the first set are needed for another ligament to be reconstructed (e.g. the posterolateral complex). The grafts when taken from the patient's own body are referred to as autograft. However not enough graft may be available or the hamstrings may be unsuitable, and in these circumstances the graft is taken from another person - this is termed allograft.
There are advantages and disadvantages of both autograft and allograft but most surgeons would agree that if possible it is best to use autograft. Autograft is safe in that it is free from the risk of infection and has the least chance of "rejection" - it is also cheap! However its supply is limited and there can be some consequences in the short and longer term from taking the graft. Allograft has the advantage of a plentiful supply but has the disadvantages of possible risks of infection, increased graft "rejection" and expense.
The choice of graft will be discussed with you in detail with your Consultant and please feel free to ask any questions at any stage about this topic, which understandably may be very important to you.
As well as the source of the tissue (i.e. autograft or allograft) there are also two choices for the actual site of the donor graft tissue;
Hamstring tendon graft (gracilis and semitendinosus tendons)
Kneecap (patella) tendon graft
Hamstring tendon graft has a number of advantages over patellar tendon graft and will usually be suggested to you as the graft of choice. It tends to be as equally effective as patellar tendon graft with a lesser risk of pain at the front of the knee after surgery. It is also easier to rehabilitate after a hamstring graft.
The hamstring tendons that will be used can be felt on the inner aspect of the thigh at the back of the knee. You will manage perfectly well without them, and in fact research now shows that they grow back to some extent.
The surgical procedure is mainly carried out arthroscopically (i.e. by "keyhole surgery"), although two small incisions are also needed, one on the inner side of the femur and the other (at the site of the hamstring tendon harvest) also on the inner aspect of the knee but over the tibia. Any other arthroscopic surgery (e.g. to the cartilage or menisci within the knee) can be performed at the same time.
Please also be aware that if the PCL reconstruction is to be carried out in conjunction with other ligament surgery (e.g. to the posterolateral corner or the anterior cruciate ligament) then additional incisions may be required for those procedures. Please see the relevant information sheet applying to that procedure.
Timing of reconstruction
The best results from PCL surgery are gained only with full rehabilitation of the knee prior to surgery, aiming to regain a full range of motion and good quadriceps and hamstring strength. This will minimize the potential risk of post-operative stiffness. The optimum time from injury (or arthroscopy) to reconstructive surgery is 4-6 weeks. This time may be longer if other structures are damaged.
Day of surgery
You will come in on the day of your surgery having starved (i.e. no food or liquids) for approximately 6 hours prior to your anticipated surgery time. Nursing staff and a physiotherapist will assess you explain post-operative procedures and measure you for crutches. You will also be requested to complete some questionnaires relating to your general health and knee.
Your Surgeon will examine your knee to ensure it is ready for surgery. He / she will also mark the leg to be operated on. This is also your chance to ask any last minute questions.
The anaesthetist will visit you to explain the anaesthetic and post-operative pain control.
The immediate period after surgery
You will wake up from the anaesthetic in the recovery area of the operating theatre. The knee will be in a tight bandage and you will have a blue Cryocuff sleeve on top. The Cryocuff contains ice cold water and helps control swelling of the knee in the early post-operative period. On return to the ward, you will rest until the following day.
The physiotherapy and bracing regime may vary from patient to patient, and in large part depends upon whether posterolateral corner or other ligament reconstruction has been necessary. The description below is the usual one employed but your Consultant will specifically outline the exact protocol to you prior to surgery.
The physiotherapist will normally place the knee in a back splint which does not allow your knee to flex for 2 weeks. A PCL brace, specifically designed to protect the reconstructed PCL, is then fitted that will limit your ability to fully flex your knee past 900. You are requested to not actively flex the knee as contracting the hamstrings to flex may place the new ligament under too much strain. However the knee can be passively flexed and this will be encouraged. Quadriceps exercises will be utilised to strengthen the thigh. Crutches are usually necessary for six weeks non-weight bearing through the operated leg, but your Consultant will specifically explain this to you as each case is different and this may not be necessary. The Cryocuff sleeve remains on the knee while at rest and removed for exercises and mobilising.
You are normally in hospital for 1 day and discharged when you are safe with crutches and able to move satisfactorily. In the early two week phase you should continue with the exercises you were shown in hospital. These exercises are vitally important for the best possible results post-operatively. You will benefit from continuing usage of the Cryocuff at home until you return to clinic approximately 10-14 days after surgery. You will be referred to start outpatient physiotherapy at this time.
In this initial 10 day period after surgery it is quite common to experience bruising and swelling in the calf, the front of the shin or inner thigh from the site of your hamstring graft. This can appear quite alarming but is not serious. You may also experience some numbness over the front of the shin or around the scar, this is normal and sensation will return over a period of time.
Rehabilitation & Physiotherapy
Physiotherapy is vitally important if there is to be a successful outcome of the PCL reconstruction. It takes a great deal of effort, commitment and time. If you do not feel you can commit yourself fully, it is probably best not to undergo the operation as you will have a less favourable result.
In general, a brief outline of stages and goals after the reconstruction are:
- Protected movement within a splint for 6 weeks
- Gym activities for weeks 6-12
- Light jog and golf at 3-4 months
- Non-contact sports training at 6 months
- Full return to contact sports at 9 months
Progress after the reconstruction is based on the time involved in the formation and maturation of the new ligament and on functional goals. All patients advance at different rates but the time factors are the average basis upon which progression is made. Progression too early may jeopardise your new ligament and cause it to rupture. At all stages you should be guided by your consultant or physiotherapist. If you have specific queries about your rehabilitation please contact either your consultant or physiotherapist.
Please be aware that this protocol relates only to a standard isolated PCL reconstruction. If there is other ligament or cartlidge damage, the rehabilitation may vary from this protocol.
Possible risks & complication
As with all procedures, there are risks of complications but these are rare. PCL reconstruction, especially recently, has a good record of safety and success. If complications occur, these may include:
- Stiffness of the knee
- Peristent pain over the front of the knee
- Persistent swelling of the knee
- Deep venous thrombosis (DVT). It is advisable not to take the oral contraceptive pill for 6 weeks prior to surgery or HRT at the time of surgery. Please ask for advice if necessary.
- Infection of the knee. This is a rare but extremely serious complication. Antibiotics are given during and shortly after the operation to minimise the risk.
- Failure of the graft.
- Damage to the popliteal artery or vein. These large blood vessels lie at the back of the knee. During the PCL reconstruction, when on of the "tunnels" is made in the tibia to allow passage to the graft, damage can rarely occur to these vessels. The operation is performed under image intensifiers to minimise risk but patients should always be aware of the risk of damage to the vessels during the operation. These risks will be discussed in your consultation.
- Swelling of the calf.
Please contact the hospital at which you undewent 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.
We hope this guide has been useful. If you have any questions relating to this please ask your consultant.