[17156236]
Patient admitted for revised hinge mechanism status post knee arthroplasty. Patient had bilateral total knee arthroplasties almost 4 years ago for treatment of severe hyper extension deformities and laxity of both knees, resulting from an electrocution injury when the patient was young. Records of the previous surgery from almost 4 years ago are not available. Surgeon reports that initially both knees did well with only residual 10 degrees hyper extension but in the last 6 months, right knee has gradually gone into almost 30 degrees hyper extension again. Presumed failure of the hinge mechanism; thus a custom implant was made that would allow for a one-piece hinge that would stop the knee at slight flexion rather than neutral or slight hyper extension. At office visit approximately 5 months ago, patient reported feeling like something snapped in the right knee when attempting to stand up. Since then, it has been more painful and the patient has had more difficulty walking. Patient has resumed wearing a full leg brace and uses two canes to walk. Physical exam shows hyper extension of the right knee slightly more than the left knee. X-ray showed no abnormality of femoral or tibial component on either ap or lateral view. Both stems remain well positioned and both prostheses appear to be well fixed. On physical exam approximately four months ago, the right knee was hyper extended 40 degrees. Patient went to surgery approximately 2 weeks ago for revised hinge mechanism. When the distal femur and proximal tibia were exposed, there was some blackish color to the synovium, suggesting a metal failure. The surgeon removed the bolt in the proximal tibia, which united the two-piece hinge and there discovered that the junction between the hinge and the shaft bolt had fractured and this resulted in the instability of the components. Surgeon removed the polyethylene insert in the lower position of the bolt along with the fragmented pieces of metal. The hinge bolt and mechanism were removed from the distal femur; then a new custom-made single piece hinge was inserted. The surgical procedure was completed and patient went to recovery in satisfactory condition. Patient did well post-operatively.
Patient Sequence No: 1, Text Type: D, B5