National Football League Players Have Higher Rates of Knee Extensor Mechanism Tears during Short and Normal Rest Weeks versus Long Rest Weeks

Abstract

Lower extremity injuries, particularly knee injuries, in National Football League (NFL) players are common. Extensor mechanism ruptures often require season-ending surgery. These ruptures, involving structures like the quadriceps and patellar tendons, are caused by powerful movements that overload the knee. Research on NFL injury risk factors, including time between games, is growing, but studies on rest periods and knee injuries have shown mixed results and are limited in scope. No prior research has specifically examined extensor mechanism tears in relation to short, normal, or long rest periods between games. Using publicly accessible resources (NFL injury reports, Pro-Football-Reference.com, and ESPN.com), an online search was conducted to identify NFL players who tore their quadriceps tendon or patellar tendon between the 2009 and 2023 seasons. Only regular season injuries after week 1 were included. The date of injury and prior game date were collected in order to calculate the length of rest. Next, each injury was categorized as a short (<7 days), normal (7 days), or long (>7 days) week injury. Other factors, such as age, football position, and playing surface (natural grass or artificial turf), were also collected. A total of 58 players met inclusion criteria. There was no difference in extensor mechanism injury rates between short weeks and normal weeks. Players were 4.7 times more likely to tear their extensor mechanism during normal weeks than long weeks (p = 0.0039) and 3.7 times more likely to tear their extensor mechanism during short weeks than long weeks (p = 0.0385). Regarding playing surface, extensor mechanism tears were more likely to occur on artificial turf than natural grass (p = 0.0324). During the 2009-2023 NFL seasons, players were found to have 4.7 times higher rates of knee extensor mechanism tears during short (<7 days) rest weeks and 3.7 times higher rates during normal (7 days) rest weeks between games, when compared to long (>7 days) rest weeks. There was no difference in knee extensor mechanism injury rates between the short and normal rest weeks. Level of Evidence Level III.