Total Knee Arthroplasty After Knee Arthroscopy in Patients Older Than 50 Years.

Several orthopedic registries have described the incidence of total knee arthroplasty (TKA) in patients who have undergone knee arthroscopy. Patient risk factors may play a role in the conversion rate from knee arthroscopy to TKA. This study quantifies the incidence of conversion of knee arthroscopy to TKA from a US mixed-payer database and describes some common patient risk factors for conversion. The medical records of more than 50 million patients who were treated between 1998 and 2014 were mined with a commercially available software platform. During the study period, a total of 68,090 patients older than 50 years underwent knee arthroscopy for partial meniscectomy, chondroplasty, or debridement. Reported rates of TKA at 1, 2, and 3 years after arthroscopy were 10.1%, 13.7%, and 15.6%, respectively. Obesity, depressive disorder, rheumatoid arthritis, diabetes, and age 70 years and older were associated with increased relative risk of conversion to TKA at 2 years. When obesity was combined individually with the top 5 other risk factors, no combination produced a higher relative risk than that of obesity alone. Patients who were 50 to 54 years of age had the lowest incidence of conversion to TKA (8.3%, P<.001). Men had a lower incidence of conversion to TKA (11.3%) than women (15.8%, P<.001). This information can help surgeons to counsel patients on the incidence of TKA after knee arthroscopy and identify preoperative risk factors that increase risk. [Orthopedics. 2016; 39(6):e1041-e1044.].