You know you’re having a bad day at the gym when both your knees dislocate during a leg-press workout. That is what happened to a 44-year-old male recreational weight lifter who “locked out” both his knees while trying to press 1,100 lbs. This unusual case is described in the latest issue of JBJS Case Connector.
Knee joint dislocations are true emergencies because of the potential for concomitant neurovascular injury. This patient was transferred to a tertiary academic hospital for emergency closed reduction and application of knee-spanning external fixators. Although both tibiae were dislocated anteriorly, both lower extremities were neurovascularly intact.
One month after the initial injury, the external fixators were removed and the knees were placed in bilateral hinged braces. MRI performed shortly thereafter revealed tears of multiple ligaments and distal popliteus tendon tears in both knees. At 4 months postinjury, the patient underwent left-side ACL reconstruction, PCL reconstruction, FCL repair and reconstruction, popliteal reconstruction with allograft, and a popliteofibular ligament reconstruction. Seven months after that, he underwent similar procedures on the right side.
At the most recent postsurgical follow-up, 17 months after the initial injury, the range of motion in both knees was 0° to 130°, and the patient was able to participate in straight line running, squats, and cycling.
The authors emphasize that any locking of the knees results in 5° to 10° of hyperextension, which places an increased load across the ACL. Add to that the heavy weight and the abrupt increase in velocity at the extreme range of motion, and you have a recipe for serious injury. The authors conclude that “the risk of knee dislocation can be reduced by avoiding locking and hyperextension of the knees during any type of leg press or squatting exercise.”
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