Total Knee Replacement in Nonambulant Patients: Osteoporosis, Severe Fixed Flexion Deformity, and Weak Extensor Mechanism “the Terrible Triad”

Abstract

Abstract Background: Knee osteoarthritis is among the most disabling disorders in elderly. With delay in proper management, muscular weakness, progressive flexion deformity (FD), and disuse osteoporosis “the terrible triad” are serious consequences, which could be major obstacles for the planned total knee replacements (TKRs). High risk for iatrogenic fractures, difficult gap balancing and failure to promote the patient activity are common expectations. Materials and Methods: A retrospective analysis of all TKRs that were done in a university specialized unit between January 2015 and January 2021 searching for nonambulant-patients was done. Twenty-two replacements for 15 patients who were unable to walk at least 3 months before surgery were found. The median fixed FD (FFD) before anesthesia was 45°. Osteopenia was evident on X-rays and bone thickness intraoperatively. Quadriceps muscle strength was not more than grade four. The median preoperative functional KSS was 0°. The median preoperative WOMAC score was 90.63. Results: Twelve knees had remaining FFD 1 year after surgery with a median of 5°. Ten had iatrogenic fractures mostly affected the medial femoral condyle. One patient could not regain walking capability and 11 patients could not walk without assistance. The median postoperative functional KSS and WOMAC scores were 61 and 21.36, respectively. Conclusion: TKRs in nonambulant patients with evident terrible triad (muscle weakness, osteoporosis, and FFD) is a risky procedure. Common complications include iatrogenic fractures and inability to regain normal physical capabilities. Despite the magnificent improvement in function, we do not recommend performing TKRs in such patients without strict patient counseling with possible drawbacks.