Limb fracture and pinning of the broken bone
Esther van Praag Ph.D.
Warning: this page contains pictures that may be distressing for some persons.
Rabbits
are preyed-on animals, which must be able to flee and run rapidly. Their
limbs are therefore powerful, while their skeleton is light, and comprises
only 7 to 8% of the body weight. In comparison, the skeleton of a cat makes
up about 12 to 13% of the body weight. Spine and limbs are thus more prone to
fracture in rabbits, as compared to other animals.
Back injuries are often observed at the lumbar level.
Additional health problems, like osteoporosis and/or low calcium diet can
render the bones brittle and fracture can happen when a rabbit panics, is
improperly restrained or picked up, or dropped. The result is often paralysis
of the lower limbs, accompanied by incontinence. Fracture of the tibia is another danger in rabbits. They
are often caused by improper handling, or caging, when a limb becomes trapped
in improperly sized wire mesh. Fractures of limbs are often comminuted (more
than two broken pieces of bone). Fractures in lower limbs (below elbow) are
often open, due to the minimal presence of soft tissue. They are often
difficult to treat, and need to be mended with patience, in order to avoid
further tearing of the skin. The wound must be sterilized, and the fractured
bone pinned or splinted if the lower part of the limb is affected.
Osteomyelitis (bone infection) and/or gas gangrene can quickly set, and
should be treated appropriately with broad-spectrum antibiotics. It is
furthermore advisable to do a bacterial culture, in order to determine which
ones (aerobic - anaerobic) have possibly contaminated the wound. Diagnosis and first aid A rabbit that has a broken limb does not necessitate
emergency medical care, unless there is shock, bleeding, respiratory or
cardiovascular problems. Immediate pain medication is recommended, in order
to comfort the rabbit and keep him/her quiet. X-rays and a complete physical and neurological
examination must be done in order to determine the damage, further treatment
and prognosis of wound healing.
Use of intramedullary
fixation The technique of intramedullary
pinning is of common use in small animals and is relatively simple. It requires
nevertheless patience and technical expertise, associated to a good
understanding of biomechanics and healing of fractured bones. Intramedullary fixation is optimal
for use in rabbits as the implant will help give bear the weight of the body,
although healing-time may be delayed. Steinmann pins, Kirschner wires and/or cerclage
wire is commonly used in rabbits. Smooth intramedullary
pins are preferred over partially or fully threaded pins. In dwarf or small
rabbit breeds, the pin can be replaced by a (hypodermic) needle. The pin or
needle must, however, imperatively take 60 to 70% of the medullar
center.
The Steinmann pin is usually inserted by hand or by means
of a Jacobs chuck. It can be inserted either at the fracture site (retrograde
insertion) or at the end of the bone (normograde
insertion) and be driven through the fracture site. The protruding end of the
pin is cut, in order to avoid damage of the skin, bacterial infection, or
interference with the joint, unless an external skeleton fixation system is
used, in which case the pin should be left protruding.
Open fracture repair techniques necessitate appropriate
sterile working conditions, accompanied by profuse cleaning of the surgery
site. According
to the location of the fracture, padded bandages, auto-adhesive bandage or
casts can be used.
Post-surgical treatment Post-surgical
care includes regular examination of the mended fracture for bacterial
infection, loosening of the pin or needle, and fracture healing. The removal of
the pin is based on X-ray pictures. It is usually around 6 weeks
post-surgery. In rare cases, where the health of the rabbit is affected, the
pin can be left in the bone.
Pain is a signal that leads to a
decreased use of the body part, in order to avoid further damage. It is
deleterious, as lack of use and spasms lead to weakness, loss of muscle tone,
and irreversible damage. Pain medication is thus very important. A good
choice of analgesics is available for orthopedic pain: • Opioids: -
Butorphanol; -
Buprenorphine. • NSAIDs: -
Flunixin; -
Meloxicam; -
Aspirin. See
“Analgesics drugs for use in rabbits” for dosages. Pain will moreover cause a
loss of appetite and decreased water intake. It is thus important to keep the
rabbit well hydrated. Acknowledgement All my gratitude to Sandy Minshull and
Akira Yamanouchi (Veterinary Exotic Information Network, http://vein.ne.jp/),
for the permission to use their pictures. Thanks also to 11 year old Herman. Further information Flecknell P. BSAVA Manual of Rabbit
Medicine and Surgery, UK: British Small Animal Veterinary Association; 2000. Hillyer E.V. and Quesenberry K.E. Ferrets, Rabbits, and Rodents: Clinical
Medicine and Surgery, New York: Saunders; 1997. Manning
P.J., Ringler D.H., Newcomer C.E. The Biology of
the Laboratory Rabbit, New York: Academic Press; 1994. Richardson
V., Rabbits: Health, Husbandry and Disease. Blackwell Science; 2000. |
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