ACL Tears

Risks And Possible Complications Of ACL Surgery

Any surgical procedure has possible risks and complications. 

The risks and possible complications for ACL surgery include:

Surgeons make every effort to minimise these risks.

Deep Venous Thrombosis (DVT)

A thrombosis is a blood clot. Deep venous thrombosis occurs when blood clots form in the blood in the deep veins of the leg. It can occur after any operation, but is more likely to occur following surgery on the hip, pelvis, or knee.

A deep venous thrombosis (DVT) may cause the leg to:

  • Swell
  • Become warm to the touch
  • Become painful

Surgeons take preventing DVT very seriously. Some of the commonly used preventative measures include:

  • Encouraging movement of the leg as soon as possible after the surgery. Moving the legs gently reduces the chances of a blood clot forming.
  • Pressure stockings worn on the legs that help keep the blood in the legs moving.
  • Medications that thin the blood and prevent blood clots from forming.


The chance of getting an infection following ACL reconstruction is very low. Yet precautions are taken before and after the procedure to prevent this serious complication. Antibiotics are given intravenously just before the start of surgery and again after surgery. Proper care of the surgical incisions by the nursing staff, and thorough education about proper incision care prior to discharge from the surgical center, will limit the chance of infection. The meticulous work of the surgeon is another important factor in preventing infection.


Although rare, excessive scarring inside the knee joint after ACL reconstruction can lead to an increasingly stiff knee. Range-of-motion exercises immediately after surgery are important to prevent knee stiffness. Physical therapy is begun shortly after the surgery. Stiffness can occur if the surgery was performed too soon after the injury, when the knee was not yet able to bend through its normal range of motion. That’s why a surgeon will not reconstruct a torn ACL unless the knee is moving well.

Graft Impingement

If the drill holes in the bone (the bone tunnels that were made to hold the new ACL) are incorrectly placed, then the newly placed graft may press against the bone as the knee bends or straightens, and restrict the normal movement of the knee. Most commonly, it becomes impossible to fully straighten the knee.

Occasionally this problem may resolve with physical therapy. Usually, another arthroscopic procedure is required to shave away some of the obstructing bone to give more room for the new graft. This may not resolve the problem and further surgery may be required to drill new tunnels in order to place the graft in the proper position inside the knee.

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