A bone screw assembly includes a first body, a second body, and a thread locking assembly that may couple the first body with the second body. The first body includes a proximal portion, a distal portion that may pierce bone in response to rotation of the first body about the longitudinal axis, and a first threaded section that may engage bone. The second body defines a through hole that may receive the distal portion of the first body. The thread locking assembly includes a first thread locking section associated with the proximal portion of the first body, and a second thread locking section associated with the through hole of the second body. Either the first threaded locking section or the second threaded locking section deforms the other in response to rotation of the first threaded locking section relative to the second threaded locking section.