Semi-constrained and constrained knee arthroplasty for distal femur nonunion & mal-union.

Background: This study aims to evaluate the outcomes and complications associated with the use of semi-constrained and constrained prostheses in addressing mal-union and non-union of distal femur fractures. The objective is to provide a pain-free, mobile, and stable joint. Methods: The study involved 9 patients with a mean age of 48.7 ± 12.2 years, the majority of whom were male (7 out of 9, or 77.7 %). Seven cases were completed in a single stage, while the remaining two cases were conducted in two stages, with a two-day interval between them. All patients were monitored at regular intervals of 6 weeks for the first 6 months, and then every 6 months for a duration of 3 years. Results: The median duration of follow up was 24 months with a range of 18-72 months and majority (55.5 %) of them had follow up for 24 months. Maximum of the study subjects (66.7 %) had range of motion ranging from 81 to 120° postoperatively, 100.0 % did not require assistance while walking and 22.2 % reported complications where two of them required staged short interval replacement and one along with that had post-op superficial wound infection for 15 days. Conclusion: Hinged knee prosthesis is a useful single stage option that allows immediate full weight bearing, restores most patients to an acceptable functional status capable of doing all activities of daily living and gives favorable outcomes.