Effective use of ultra-high molecular weight polyethylene cable and Krackow suture for stretched out patellar tendon due to scarring in a case with rheumatoid arthritis post-total knee arthroplasty

Patellar tendon rupture is a severe complication following total knee arthroplasty (TKA). We encountered a case of rheumatoid arthritis with an incomplete rupture of the patellar tendon post-TKA. An 84-year-old woman was diagnosed with an incomplete rupture of the right patellar tendon 3 months post-TKA of her right knee. The patient exhibited a 45° extension lag 6 months post-TKA, necessitating reconstruction surgery. Intraoperative findings revealed incomplete rupture of the patellar tendon that was stretched out, diagnosed as incomplete patellar tendon rupture. Due to knee valgus instability (passive knee valgus showed 20°), the thickness of the tibial insert was adjusted from 11 to 15 mm, resulting in improved valgus instability. The scarring region of the patellar tendon was resected to 10 mm in length, and the tendon was repaired using an ultra-high molecular weight polyethylene cable (Nesplon cable) and Krackow suture. The repair was secured by making an 8-figure pattern with the cable. After the reconstruction surgery, the knee was immobilised at 0° extension for 3 weeks, followed by the initiation of range-of-motion exercises. Three months later, the extension lag was reduced to -15°, and the patient could walk without orthosis and reported neither instability nor surgical site infection at 8 months after the surgery. In conclusion, this case is notable due to the rarity of incomplete (stretched out) patellar tendon rupture post-TKA and demonstrates the effectiveness of Nesplon cable with Krackow suture in reconstruction surgery.