Background: There are no clear indications for conversion of knee fusion to total arthroplasty. In this paper we report outcome and complications in 8 patients.
Patients and methods: We reviewed 8 total knee arthroplasties after takedown of previous fusion 24-55 months after the conversion. The original diagnoses were complications following injury in 3 patients, rheumatoid arthritis in 3, complication after chondromalacia in 1 patient and tuberculous arthritis in 1 patient. The age at operation ranged from 31 to 67 years. The time since arthrodesis ranged from 1 to 49 years.
Results: 5 patients had to undergo reoperation for postoperative complications. 2 patients experienced recurrence of previous deep infection, which led to thigh amputation in one and chronic fistulation in the other. Only 1 patient had an uneventful course after the conversion procedure, but he died later on due to a heart attack. As another patient also died of cardiovascular disease, 5 of the 8 patients were available for evaluation of knee function. In these patients the knee flexion ranged from 90 to 120 degrees, extension lag ranged from 10 to 40 degrees, and all knees were aligned at 6 to 8 degrees of valgus. The Knee Society clinical scores ranged from 47 to 74, the Womac scores ranged from 9 to 47, and EuroQol ranged from 0.1 to 0.8.
Interpretation: Our findings indicate that conversion of knee arthrodesis to total arthroplasty should only be performed in selected cases, and after giving the patient extensive information about the high risk of rather serious complications.