Extensor Mechanism Injuries after Primary Total Knee Arthroplasty

Background : Extensor mechanism injuries after total knee arthroplasty (TKA) continue to be a difficult complication to treat and can be associated with devastating outcomes. This study attempts to review the prevalence, treatment types, and outcomes of extensor mechanism injuries after total knee arthroplasty within a cohort of patients. Methods : Using a clinical research database, a retrospective cohort study was performed via chart review of patients who underwent a total knee arthroplasty over the course of 7 years from 7 hospitals within the same hospital system. The charts were then screened for subsequent operative repair of the ipsilateral extensor mechanism at a later date. Patient characteristics, implants, type of extensor mechanism injury, fixation type, subsequent surgeries were evaluated. Results : Of the 6064 total knee arthroplasties, 104 patients with 105 (1.73%) knees went on to have extensor mechanism injuries. Quadriceps tendon injuries were the most common, followed by patellar tendon, and then patella fractures. Median time to injury was 70 days. Patients requiring additional surgery beyond initial repair of extensor mechanism injury was 47.6% (50/105). Additionally, 33% (35/105) went on to have revision of component(s) and 17.1% (18-105) received treatment for prosthetic joint infection. Conclusions : While overall rare, extensor mechanism injuries after total knee arthroplasty can pose serious complications beyond initial repair, including need for additional surgery, infection, revision, and even amputation. Careful consideration should be taken by the treating surgeon when faced with these injuries to avoid further complications.