WEST Coast's already weakened ruck division has reached breaking point, with big man Nathan Vardy under a fitness cloud with a right elbow injury. 

The 25-year-old's elbow hyperextended when his fist became caught under Fremantle captain Nat Fyfe's arm in a marking contest during the first quarter of the Western Derby. 

Vardy was in significant pain when he left the field, but managed to return later in the quarter with his elbow heavily strapped. 

Should Vardy be unavailable for Saturday's away clash with Port Adelaide, he will join fellow talls Scott Lycett (shoulder), Nic Naitanui (knee) and Drew Petrie (hand) in the Eagles' large casualty ward. 

Geelong small forward Brandan Parfitt suffered a right hamstring injury as he sprinted for a loose ball on the wing in the final quarter against Collingwood. 

The 19-year-old immediately reached for his upper leg and fell to ground, before being slowly assisted from the field by trainers.

Carlton youngster Jack Silvagni will have scans on Monday to determine the extent of the right AC joint injury he suffered when he collided into Swan Zak Jones in the second quarter.

Silvagni did not return after the incident and watched the second half with his arm in a sling.

Western Bulldogs midfielder Tom Liberatore's night against GWS ended in the opening play of the final quarter after his head hit the turf in a forceful tackle from Giant Shane Mumford.

Liberatore was noticeably groggy as he made his way off the ground with the help of the medicos, and watched the rest of the game from the bench due to concussion. 

Sydney forward Gary Rohan was involved in a sickening fall in the third quarter against Carlton, but was later cleared of any structural damage. 

The 25-year-old went back with the flight of the ball, jumped and collided into Carlton defender Sam Rowe, before his body twisted in the air and sent him landing on the back of his neck. 

Rohan, who only made his comeback in round five following pre-season back issues, lay motionless on the ground and was taken off on a mobile stretcher.

A Swans spokesperson told AFL.com.au on Sunday that Rohan suffered concussion in the nasty fall.

The club had earlier reported Rohan was alert in the rooms soon after the incident and was taken to hospital as a precaution, where he spent the night. 

GWS defender Nick Haynes will miss around 10 weeks after suffering a hamstring tendon tear against the Bulldogs.

The 24-year-old landed awkwardly in the splits position following a one-on-one marking contest in the final quarter and walked off the ground gingerly. 

The club said Haynes would not need surgery to repair his hamstring at this stage. 

Giants ruckman Shane Mumford tweaked his right ankle at a boundary throw-in early in the first quarter against the Bulldogs, but scans over the weekend cleared him of serious injury. 

Mumford went to the rooms for treatment and got through the full match despite the complaint, and will need to pass a fitness test this week. 

Giants forward Sam Reid will also be tested after picking up a left hamstring injury in the final term, finishing the match on the bench with ice strapped around his leg. 

In other injury concerns in round six:

- Collingwood veteran Travis Varcoe hobbled off the ground with a right hamstring complaint in the third quarter against Geelong. The 29-year-old emerged from the rooms and performed run-throughs along the boundary, but failed to return. Varcoe missed five of the first seven games last season due to a hamstring injury.

- Essendon forward Mitch Brown hurt his right ankle after it became caught under Jordan Lewis in the closing minutes of the clash with Melbourne, as the star Demon attempted to spoil the mark. 

- Gold Coast wingman Matt Rosa received an accidental knee to the head from North Melbourne's Sam Gibson in the second quarter and took no further part in the game due to concussion. 

- Suns midfielder Aaron Hall also suffered an accidental knock to the head in a tackle from Kangaroo Sam Gibson in the final quarter, bringing a premature end to his night with concussion. 

- West Coast midfielder Liam Duggan (corked leg) and debutant Kurt Mutimer (knee) were sore following Saturday night's Western Derby and will need to pass fitness tests this week.

- GWS defender Aidan Corr picked up a buttock complaint in the first quarter against the Bulldogs. The 22-year-old performed run-throughs along the boundary and managed to play out the game. Giants coach Leon Cameron said Corr was feeling "a bit tight" post-match, but scans later cleared him of serious injury. 

- Carlton swingman Jacob Weitering received a corked left thigh in a contest in the third quarter and came back to the field momentarily with his leg heavily strapped, only to limp back off after being unable to run freely. The medicos replaced the strapping on Weitering's leg and he returned in the final term.

- Carlton forward Billie Smedts suffered a corked right quad in the final quarter against Sydney, and returned to see out the game despite moving with a noticeable limp. 

- Western Bulldogs veteran Bob Murphy rolled his right ankle as he was being tackled by Giant Zac Williams midway through the third term. He had his lower leg assessed on the bench and came back soon after. 

- Bulldogs midfielder Luke Dahlhaus hurt his right wrist attempting to smother Giant Callan Ward in the last quarter, but returned to the field shortly after. 

- St Kilda defender Nathan Brown hyperextended his right knee in a contest with Hawk Will Langford in the third term. Brown had a knee stability test at the interchange area and returned in the latter part of the quarter with his leg strapped.