Classification-Based Management of Stiff/Ankylosed Knees.

INTRODUCTION: Stiff knees are defined as those with an arc of motion < 50°. They pose a considerable surgical challenge to the operating surgeon. Based on our experience to deal with these complex cases, we have developed a working classification that outlines a flowchart to manage the stiff/ankylosed knees.
MATERIALS AND METHODS: It was a retrospective study conducted in our department. Out of 570 TKA performed in last 5 years, 57 had stiffness and four had bony ankyloses (total 61 knees). Patients were classified based on the fibrous or bony ankylosis and preoperative ROM.
RESULTS: Patients were followed for an average 2.4 years (1.8-5.5 years). KSS pain scores improved from an av. 32 preop (18-64) to av. 76 postoperatively (61-90). The KSS function scores improved from a preoperative value of 36 (16-56) to an av. 78 (52-90) postoperatively. ROM improved from an average of 35.6° (0°-44°) preoperatively to an average of 95.6° (ROM 73°-118°) postoperatively. Extension lag was an av. 8° (3°-12°) and was seen in 13 patients postoperatively. Residual fixed flexion deformity was an av. 7° (3°-14°) and seen in 17 patients. The stiff knees (type 1 and type 2) fared better than ankylosed knees (type 3) in all aspects. Complication rate was high (24%) in our series.
CONCLUSION: Our classification of stiff/ankylosed knees guides the surgeon to decide upon which approach to take, which implants to keep handy and has a predictive and prognostic value. © Indian Orthopaedics Association 2021.