TUMOUR OR TRAUMA?
AN UNUSUAL TIBIAL PLATEAU FRACTURE

P Kelly, PG Murphy, J. Rice, L Rajah, R Moran
Orthopaedic Department, Beaumont Hospital, Dublin.

Tibial plateau fractures encompass a wide variety of fracture configurations with differing degrees of articular depression and displacement. The extent of articular depression has been described in the literature as being generally less than 20mm. We describe a case of a lateral tibial plateau fracture with depression of articular cartilage to 50mm. This initially raised the suspicion of a coincidental tibial metaphyseal tumour pre-operatively.

CASE REPORT

A 26 year old man presented following a fall from 12 feet landing on his right foot. Plain radiography showed a fracture of the lateral tibial plateau (fig 1.). A 2cm by 2cm radio-dense area was also seen 5cm below the tibial articular surface as shown on tomograms of this region (fig 2). This was regular in outline and suggested the presence of a bone neoplasm. The patient had no other injuries.

Open reconstruction of this fracture was undertaken through an antero-lateral approach. Arthrotomy of the knee joint revealed detachment of the anterior horn of the lateral meniscus and a depression of the articular surface of the lateral tibial plateau. The anterior cruciate ligament was intact and varus-valgus stressing of the joint showed that both medial and lateral collateral ligaments were intact.

Access to the depressed fracture segment in the medullary cavity of the proximal tibia was gained by performing a vertical osteotomy and hinging the lateral cortex on the lateral collateral ligament. This manoeuvre revealed a circular central portion of the articular surface that was depressed on average of 5cm below the joint line of the knee. This depressed articular surface was elevated and cancellous bone graft was packed underneath. The lateral cortex was reduced and two cancellous screws were applied sub-condrally. A 3.5mm reconstruction plate was applied to the lateral aspect of the tibia (fig 3). The anterior horn of the lateral meniscus was reattached.

Continuous passive movement of the knee joint was instituted immediately post-operatively. The patient was discharged one week post-operatively in a hinged knee brace. At this stage 100° of flexion was possible and the patient mobilised non-weight bearing with two crutches.

Two months post-operatively there was radiological evidence of fracture healing and the patient began symptom limited weight bearing.

DISCUSSION

Schatzker in 1979 classified fractures of the tibial plateau in terms of their injury pattern and therapeutic requirements. He recognised six such patterns.

Type I

    A wedge fracture of the lateral tibial plateau. This occurs in young people. Operative repair is indicated in displaced fractures as the meniscus may become trapped in the fracture line.
Type II
    A lateral wedge fracture with depression of the adjacent tibial plateau. This fracture occurs in older people with osteoporotic bone. When operative repair is carried out, a buttress plate is usually indicated on account of this porosis.
Type III
    A depression of the lateral tibial plateau without an associated wedge compression fracture. This is the commonest type of injury. Operative intervention to restore the articular congruity plus bone grafting of the medullary defect is frequently successful.
Type IV
    A fracture of the medial tibial plateau. This fracture is associated with a varus force. When this fracture occurs with low velocity, it is usually associated with osteoporosis and operative repair is therefore difficult.
Type V
    A bicondylar fracture which consists of a wedge compression of the medial and lateral plateaux. This fracture is associated with varus-valgus instability. Operative reconstruction with bilateral buttress plates is proposed.
Type VI
    A complex fracture of the tibial plateau with a fracture line separating the metaphysis from the diaphysis. Traction tends to distract this fracture line and thus has no role to play in the management of this type of injury. The injury described in this case report may be classified as a type II fracture. It is most commonly seen in older age groups and relative weakness of the medullary bone is implicated. The stability of the joint is rarely affected in this type of injury as the collateral ligaments along with the anterior and posterior cruciates are intact. This contrasts with fractures associated with cortical depression. The collateral ligament on the side of the depression has impaired function. The opening up of the knee joint associated with the depression may rupture the contra-lateral collateral ligament and the anterior cruciate ligament.
This patient was a good candidate for operative intervention as he had minimal soft tissue damage and good bone quality. His treatment was based on the following principles proposed by Schatzker;

    1. Anatomical reduction of the joint surface.
    2. Elevation of the depressed plateau en masse.
    3. Bone grafting of the metaphyseal defect.
    4. Stable internal fixation.
    5. Early motion.

CONCLUSION

We report an intra-articular fracture of the proximal tibia with gross depression of the articular surface. This injury was managed operatively along with the defined principles with good early results.