Primary Total Knee Replacement in a Patient with failed High Tibial Corrective Osteotomy: A Case Report

Background: Cases of elderly patients presenting with nonunion following high tibial osteotomy for genu vaum are now very rare. This is because corrective osteotomy around the knee in middle age and elderly has lost its importance over the years due to successes of total knee replacement.For the very few that present, several options of treatment, such as revision plating, intramedullary nailing or illizarov compression osteosynthesis exist. These are however not without limitations such as the need for prolong immobilization, development of joint stiffness, soft tissue contractures, recurrent nonunion and subsequent worsening of osteoarthritis of the adjacent joint (knee). We report primary total knee arthroplasty in a patient presenting with nonunion following failed high tibial osteotomy, using diaphyseal engaging stem (DES) in form of tibia extension rod. To the best of our knowledge we have not come across similar report in the country.Method: K.S is sixty two year old woman who presented with inability to walk. Prior to her presentation, she underwent high tibial corrective osteotomy for medial unicompartmental osteoarthritis of the right knee 3 years ago. She developed nonunion necessitating revision surgery (replating) a year and 7 month after first operation (2016), which resulted in nonunion again. Diagnosis of Post Osteotomy High Tibial Nonunion with bone loss was made. She was optimized and underwent total knee replacement with tibia extension rod.Result: She was able to mobilize on the 7th day post operative with the aid of walking frame and was discharged on the 14th day. At 11 month follow up, she mobilises comfortably and pain-free without aid with radiological union at fracture site.Conclusion: Semi constrained Total Knee Replacement with extension rod may be an option for treating failed high tibial corrective osteotomy coexisting with moderate to severe ipsilateral knee osteoarthritis. Keywords: Total Knee Arthroplasty, Tibial Extension Rod, Failed High Tibial Osteotomy