During a particularly lively playful episode Jingles gave a cry and began limping on her right hind leg.
The next day she was brought to the surgery nearly 100% lame on the right hind and with obvious pain and some swelling on the front of the stifle area.
An X-ray confirmed that she had a partial avulsion of the tibial crest. An avulsion fracture is where a small piece of boney tissue (the tibial crest) is pulled away from the main bone by the action of a tendon.
It's usually self-induced and happens during forceful activity in young dogs between 5 months and 10 months of age, before the bones are fully formed.
The piece of bone pulled away is a separate centre of ossification which is attached to the main bone by soft cartilage tissue.
After 10 - 12 months of age these separate centres of bone growth become fully calcified and joined to the main bone.
Jingles waking up after anaesthetic and X-ray
X-ray of the left stifle joint (side view - i.e lateral view)
The upper bone is the femur with a normal patella (kneecap) on the left.
The lower bone is the tibia showing a separate centre of ossification (tibial crest) which, although it looks like a fracture, is normal at 5 months of age.
X-ray of the right stifle (side view - i.e lateral view)
The tibial crest of tibia (the lower bone) has been pulled away (avulsed) from the tibia, widening the gap and leaving a boney fragment behind.
Treatment: Tibial crest avulsions usually result in much greater displacement of the boney fragment (see X-ray below) and generally require surgical repair.
As Jingles' fracture was not greatly displaced we decided to treat her with anti-inflammatory medicines and rest.
After 10 days she was much improved and 4 weeks later she was walking normally.
X-ray of the stifle of another case for comparison, (lateral view) - showing compete avulsion of the tibial crest of the right stifle.
The avulsed bone has turned through 120 degrees and required surgery to anchor it back in the correct position.