This infomation is designed to explain the anatomy and function of the posterolateral complex (PLC), what can happen as a result of injury, a description of the surgery to reconstruct these structures and the rehabilitation thereafter.
Most but not all reconstructions of the PLC are performed in association with reconstruction of another of the knee ligaments. If this is the case please also refer to the information sheet relating to the other ligament(s) as well.
The posterolateral compartment of the knee is a complex arrangement of ligaments, joint capsule and muscles. This arrangement acts as both a static and a dynamic stabilizer of the knee, controlling outward rotational movement backwards of the tibia (shin) on the femur (thigh). This movement can be imagined with the knee bent, keeping your thigh still and turning your foot outwards.
Although PLC injury is uncommon, it is often associated with other ligament damage in the knee, such as the cruciate ligaments. The mechanism of injury is often the knee pushed back on itself with the lower leg turned out or a direct blow. As a result of injury the knee may become extremely unstable giving way on twisting or pivoting activities. There may be an altered walking pattern such as the foot turned outwards, the knee slightly flexed or a ‘thrust’ of the knee as you walk.
If you are undergoing a PLC reconstruction in conjunction with other ligament reconstruction please read the relevant information sheet which gives more full details about your proposed operation. However the description given below is usually indicative of what a PLC reconstruction entails.
There are two principal choices for the graft used to reconstruct the PLC. 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 is needed for another ligament to be reconstructed (e.g. the anterior or posterior cruciate ligaments). 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.
The operation itself of PLC reconstruction involves an incision on the outer aspect of the knee. The operation strictly speaking is not in the knee but on the outside of the joint. If the hamstring tendons are used, there will also be a small incision on the inner aspect of the knee, from where they are harvested.
The graft, of whatever type, is placed through the head of the fibula (the smaller of the two bones of the leg) and secured in the outer aspect of the femur using a screw device.
As it is likely that you are having a PLC reconstruction in conjunction with a cruciate ligament reconstruction, the PLC reconstruction will alter the operative protocol of the cruciate ligament reconstruction as stated in the patient information leaflet relating to that particular operation.
Your knee will be placed in a back splint for two weeks restricting all movement. At two weeks a brace is fitted allowing a full range of movement. You will usually be requested to remain in this brace for 6 weeks after surgery.
You will need to be non–weight bearing during this first six weeks i.e. you will need to avoid putting any weight through your operated leg. The new PLC ligament can be damaged or stretched if excessive strain is placed on it in this early phase.
On removal of the brace at 6 weeks you can then follow the normal post–operative protocol for the ACL reconstruction.
Your knee will be placed in a back splint for two weeks restricting all movement. At two weeks a PCL brace, specifically used for rehabilitation for this type of reconstructive surgery, is fitted allowing full extension (straightening) and flexion (bending) to 900. You will usually be requested to remain in this brace for 6 weeks after surgery.
You will need to be non–weight bearing for 6 weeks i.e. during this time you should not put any weight through your operated leg as this may damage the new PLC ligament.
To protect the posterior cruciate ligament graft (not the PLC) you will need to avoid actively flexing (bending) your knee for 6 weeks as active contraction of the hamstring muscles may harm the graft by placing it under too much strain.
On removal of the brace at 6 weeks you can then follow the normal post–operative protocol for PCL reconstruction.
Possible risks and complications
There is no surgical procedure that is free from complications. Ligament reconstruction, especially recently, has a very good record of safety and success, but complications can occur. Such complications can include;
The risks and complications for PLC reconstruction are essentially the same as those mentioned above. However there is one added risk with this procedure;
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 develop a problem after your surgery you do not need to contact your GP (unless you wish to do so); please telephone your Consultant, or if it is outside of office hours please contact the hospital in which you had your surgery and they will be able to contact him for you.
You will have been recommended surgery only if the potential benefits of the operation outweigh the risks. If you have any specific questions relating to your surgery or rehabilitation please contact your Consultant or physiotherapist.
Derek Bickerstaff MD FRCS FRCSED
Consultant Orthopaedic Surgeon