Symptomatic Focal Knee Chondral Injuries in National Football League Combine Players Are Associated With Poorer Performance and Less Volume of Play

Abstract

Purpose: To (1) describe the magnetic resonance imaging (MRI) characteristics of knee chondral injuries identified at the National Football League (NFL) Combine and (2) assess in-game performance of prospective NFL players with previously untreated knee chondral injuries and compare it with matched controls.

Methods: All players with knee chondral injuries identified at the NFL Combine (2009-2015) were retrospectively reviewed. Players with prior knee surgery were excluded. A knee MRI for each player was reviewed; location, modified International Cartilage Repair Society (ICRS) grade (I-IV), and associated compartment subchondral edema were documented. Position, respective NFL Draft pick selection number, games started, played, snap percentage, and position-specific performance metrics during the first 2 NFL seasons were recorded for the injury and injury-free control group composed of players with (1) no prior knee injury, (2) no significant missed time prior to the NFL (≤2 total missed games in college), (3) no history of knee surgery, and (4) drafted in the respective NFL Draft following the NFL Combine.

Results: Of the 2,285 players reviewed, 101 (4.4%) had an injury without prior knee surgery. The patella (63.4%) and trochlea (34%) were most commonly affected. Defensive linemen were at highest risk for unrecognized injuries (odds ratio 1.8, P = .015). Players with previously untreated injuries, compared with controls, were picked later (mean pick: 125.8) and played (mean: 23) and started (mean: 10.4) fewer games during the initial 2 NFL seasons (P < .001 for all). Particularly, subchondral bone edema and full-thickness cartilage injuries were associated with fewer games played (P = .003).

Conclusions: The patellofemoral joint was most commonly affected in NFL Combine participants. Previously untreated knee articular injuries in players at the NFL Combine are associated with poorer early NFL performance in comparison to uninjured players. Subchondral bone edema and full-thickness cartilage injury on MRI were associated with fewer games played during the initial NFL career.

Level of evidence: Level III, case-control study.