THE WESTERN Bulldogs have defended their handling of luckless midfielder Clay Smith, having confirmed he will have a third knee reconstruction after he ruptured his anterior cruciate ligament during the loss to St Kilda on Saturday. 

The Bulldogs released a statement on Monday confirming that Smith had damaged his knee graft in the second quarter, and insisting that his subsequent return to the field was "an acceptable risk".

Smith fell to the ground clutching his knee midway through the second term, but after being assessed by medical staff and told he had ruptured the graft he wanted to continue playing.

The Bulldogs said 21-year-old experienced no pain or swelling and completed running, jumping, twisting and weaving manoeuvres before returning to the field.

"The club's medical staff permitted him to do so on the basis of their clinical judgment that because the graft had already ruptured, the prospect of it being made worse by a second incident was an acceptable risk," the Dogs said in a statement on Monday.

On the stroke of half-time, Smith crumpled to the ground again after attempting to get to a marking contest and had to be stretchered from the field.

"The functionality of his knee in the period between the first incident and the second incident was due to the strength of his knee's surrounding musculature and the second incident constituted, in essence, the failure of the surrounding musculature’s ability to continue to provide stability to the knee," the statement said.

"The medical staff were and remain of the view that the second incident did not clinically aggravate the injury." 

The Bulldogs said its medical assessment was supported by an MRI scan on Sunday which showed only a clean tear of the ligament from the first incident and no meniscal or other structural injury.

"The club has obtained independent opinion (in knee orthopaedics and in sports medicine) from two experts, one in Australia and one overseas. 

"On the basis of our inquiries and those opinions, we are satisfied that the medical judgments made by our staff were appropriate; that the second incident did not aggravate the injury and that permitting Clay to return to the field did not put him in a position of unacceptable risk."

Saturday's match was just Smith's third game back at AFL level after his second knee reconstruction.