An Unexpected Complication of Hip Arthroplasty: Knee Dislocation

Abstract

An increasing number of patients with hip fracture have been seen with osteoporosis associated with osteoarthritis. Although knee dislocation is related to high-energy trauma, low-grade injuries can also lead to knee dislocation which is defined as "ultra-low velocity dislocation." The case reported here is of an 82-year-old patient who presented with a left intertrochanteric hip fracture. Partial arthroplasty was planned because of osteoporosis. In the course of surgery, degenerative arthritic knee was dislocated during the hip reduction maneuver with the application of long traction. The neurovascular examination was intact, but the knee was grossly unstable and was dislocated even in a brace; thus a hinged knee prosthesis was applied nine days after surgery. The patient was mobilized with crutches after the knee prosthesis but exercise tolerance was diminished. In conclusion, it should be emphasized that overtraction must be avoided during the hip reduction maneuver in patients with advanced osteoarthritic knee.

Figure 1

Left intertrochanteric hip fracture seen on radiography. It was understood from the widened femoral canal that osteoporosis was associated with the fracture.

Figure 2

Partial cemented hip arthroplasty was applied with a calcar replacing femoral stem. The femoral stem position was satisfactory in relation to the hip center.

Figure 3

The deformed knee indicating posterior knee dislocation.

Figure 4

Posterior knee dislocation seen on radiography before and after reduction with underlying knee osteoarthritis.

Figure 5

Degenerative arthritis and torn cruciate ligaments were seen and a rotating hinged knee prosthesis was applied.

Figure 6

Radiography of the hinged knee prosthesis was satisfactory.