Rabbit Model of Osteoarthritis

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Rabbit Model of Osteoarthritis

• By Emily Zhang, Walter Herzog, David Longino

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Agenda

• Introduction
• Objectives
• Methods
• Results
• Discussion
• Conclusion

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Introduction

• Currently no direct etiologic factor for
  osteoarthritis (OA).
• Muscle weakness has been hypothesized to lead to
  the onset OA.
• Deficiency of the ACL has been linked to
  degenerative change in the knee and is suggested
  as a risk factor for OA.

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Objectives
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Methods

• Seven test groups of rabbits
• 1 (7) 3.5U/kg of Botox injected into
  quadriceps
• muscles in one limb
• 2 (7) ACL transection in one limb
• 3 (2) Botox injection ACL transection in the
• same limb
• 4 (5) ACL transection Exercise
• 5 (7) Botox ACL transection Exercise
• 6 (2) Sham
• 7 (2) Sham Exercise

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Methods

• Specifications
• Botox injections were placed in three spots on
  quadriceps for even distribution
• Botox injections ACL transections were
  performed on random hind limbs
• Exercise began one week following surgery to
  allow for some recovery

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Results
Table 1 Group 1 Botox
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Results
Table 2 Group 2 ACL transection
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Results
Table 3 Group 3 ACL transection Botox
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Results
Table 4 Group 4 ACL transection Exercise
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Results
Table 5 Group 5 ACL transection Botox
Exercise
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Results
Table 6 Group 6 Sham
Table 7 Group 7 Sham Exercise
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Discussion

• Group 1
• Change in muscle mass indicated Botox is
  effective in inducing muscle atrophy.
• Higher percentage differences in muscle mass were
  seen in rabbits kept for a longer period of time,
  indicating that Botox caused further muscle
  atrophy as time progressed.
• Torque data indicated that Botox is effective in
  inducing weakness of the quadriceps.

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Discussion

• Group 2 ACL transection
• Data showed muscle weakness and atrophy
• It appeared that the effects of ACL transections
  were not as great as that of Botox.
• Group 4 ACL transection Exercise
• Data showed little difference between this group
  and group 2, indicating no signs that exercise
  improves the affected limbs condition.

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Discussion

• Group 3 ACL transection Botox
• As expected, data showed this combination clearly
  had a greater effect than each of the procedures
  alone.
• Group 5 - ACL transection Botox Exercise
• The two-week rabbits showed muscle atrophy to the
  same degree as the non-exercised three-week
  rabbits.
• The four-week exercised rabbits showed further
  muscle atrophy, likely due to the continuing
  effect of Botox. However, there is less muscle
  weakening which may be a positive effect of
  exercise.

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Discussion

• Groups 6 and 7
• Rabbits in these groups show insignificant
  differences between the sham group and the
  exercised sham group.
• In fact, these rabbits appear to have normal
  joints after four weeks.

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Discussion

• Video analysis of the rabbit gait helped to
  analyze the ground reaction force data.
• The ACL transected limbs exert very little force
  in both the medial-lateral and vertical
  directions while the control limb shows normal
  gait patterns.
• Botox limbs exert less force from the toes ijn
  pushing off compared to the control limb.
• ACL transection Botox rabbits land with less
  force from the affected hind limb. The front
  limbs took on most of the load.

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Conclusion

• Botox effectively induces atrophy of the knee
  extensor muscles in rabbits as well as increased
  weakness.
• ACL transections also produces these effects, but
  to a lesser extent.
• ACL transection Botox injections shows
  significant decrease in muscle strength and mass
  in the affected limb.
• Sham groups appear to be normal.