Figure 1. Anteroposterior radiograph of the right knee.
Figure 2. Lateral radiograph of the right knee.
A 67-year-old man presents to the office for evaluation of severe right knee pain and disability. He underwent a right total knee replacement 30 years ago that was complicated by an infection within a year. The total knee prosthesis was resected but never revised. He has since developed progressive pain and deformity in the knee, with severe stiffness. He uses crutches to walk because of instability. On examination, a valgus knee deformity of 40° is noted, and range of motion is 0° to approximately 30° of flexion. Anteroposterior and lateral radiographs are obtained (Figures 1 and 2).
Which of the following is the best treatment option for this patient?
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The patient has developed severe bony and soft tissue deformities; therefore, a total knee reimplantation is not recommended. The most common indication for treatment with a knee fusion is an unreconstructable knee following explant of an infected total knee replacement. This scenario is rare, with <1% of patients who undergo total knee arthroplasty receiving an arthrodesis procedure afterward. Another salvage procedure for this type of patient is an above the knee amputation. However, a knee fusion is more efficient and functional than an amputation as it provides a stable platform on which to walk, and requires less energy to ambulate than a prosthetic limb. A contraindication to treatment with knee fusion includes arthritis of the ipsilateral hip and ankle. Patients who undergo knee fusion compensate by increasing hip and ankle motion when walking, and arthritic pain in these joints typically increases after knee fusion. All patients who undergo a knee fusion will have a 2.6-cm to 6-cm leg length discrepancy. This requires a shoe lift that correlates with the size of the discrepancy. Techniques for arthrodesis include intramedullary nailing, external fixation, insertion of plates, or a combination of the three.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).