Fractures of the Plateau of the Tibia
The expansion of the flat upper end of the tibia which makes up the distal half of the knee joint is known as the tibial plateau. The plateau is an essential part of the weight bearing function of the knee joint and if compromised can severely affect the movement, stability and alignment of the knee, interfering with gait. The fracture should be recognised early and treated accordingly so that the chances of post-traumatic knee arthritis and disability are minimised. Over half the patients in this category are in their fifties or older.
A large group which suffer this type of fracture is older women who already have some degrees of osteoporotic change in the area. Younger people with this presentation more likely result from more high energy events. The usual way these fractures occur is for a sideways force to be applied to the knee (often in a knock knee direction) while the knee is weight bearing with a downward force also applied. The lateral condyle (most commonly) is then squashed down by the large femoral condyle on that side. Sports injuries and falling from a height can result in this injury but it is much more common secondary to a road accident.
Around 25% of this kind of injury is secondary to a person being hit by a slow speed car at roughly the height of the knee joint, the bumper being the primary contact point. Falling from a height or sporting activities including horse riding can also result in this fracture. A fracture may result from a low energy event or a high energy event, depression fractures being more common from lower energy contacts and splitting fractures more common in higher energy involvement. This type of fracture can present in many complex ways and Schatzker and co workers have proposed a classification into six subtypes which is widely used.
On assessment the surgeon will not only assess the fracture itself but the health of the surrounding tissues such as the local muscles, nerves and blood vessels. Around half of tibial plateau fractures may have accompanying injuries to the cruciate ligaments and the cartilages (menisci) which may need surgical intervention themselves. Due to the typical force being in a knock knee direction the medial collateral ligament is more likely to suffer damage than the lateral. Fractures of the medial plateau usually involve more forceful injuries due to the stronger bony areas and this can increase the risk of soft tissue complications.
Surgeons may be happy to accept a range of fracture displacement and pursue conservative or non-operative management in these cases. Lifting the depressed plateau and securing bone graft underneath it may be required if depression exceeds 5mm in depth. Open fractures, where a wound is continuous with the fracture, mean that surgery will be needed, as it is also if the blood supply has been compromised by vessel damage or if compartment syndrome has developed in the lower leg. Less severe fractures can be conservatively managed and if there is severe soft tissue compromise then surgery may have to be postponed.
With the diagnosis established the treatment plan can begin with treatment modalities targeted at lowering oedema and inflammation, including limb elevation, tissue compression, immobilisation of the area and resting the part. The removal by surgery of any non-viable dead and dying tissues (debridement) is vital to safeguard the remaining healthy tissues. Fasciotomy may be required to release excessive pressure from one or more of the leg compartments should compartment syndrome threaten the viability of the limb.
Treatment of fractures of the tibial plateau is aimed at restoring the stability of the knee joint, its correct alignment and anatomical relationships of the joint along with full movement in the knee so the knee will function well, is painless and will not suffer arthritic change. If the joint is unstable then surgery will have to be performed, holding the fragments with as little movement as possible. In younger patients with good bone quality then internal fixation may be successful, however older patients with poor bone quality may need to be functionally braced or have total knee replacement.