Computed tomographic documentation of a comminuted fourth carpal bone fracture associated with carpal instability treated by partial carpal arthrodesis in an Arabian filly.

This research article discusses the treatment of a complicated fracture to the fourth carpal bone in an Arabian horse filly. The young horse underwent a procedure called partial carpal arthrodesis, which stabilized the joint, allowed for correct limb alignment and enabled the horse to regain substantial limb function without lameness.

Methods and Procedure

• The researchers handled a case involving an 8-month-old Arabian filly. The filly had a slab fracture in her fourth carpal bone (C4), which was initially diagnosed via radiographic examination.
• The complexity of the fracture, known as comminution, was further confirmed using computed tomographic (CT) imaging.
• Upon realizing the extent of the fracture, the researchers carried out a partial carpal arthrodesis (PCA) of the middle carpal joint (MCJ) and the carpometacarpal joint (CMCJ), using two narrow dynamic compression plates.

Results

• Immediately after the surgery, the PCA provided the needed stability to the filly’s carpals and restored her limb alignment correctly.
• Within eight months post-surgery, the horse’s joints showed complete bony fusion and she was capable of significant level of carpal flexion (joint movement) without any signs of lameness while walking or lightly trotting.

Conclusions

• Compared to standard radiographic examination, CT imaging was found to be more effective and accurate in defining the extent and complexity of the fourth carpal bone fracture.
• PCA was chosen as a treatment procedure due to the instability and lateral collapse of the MCJ and CMCJ on the horse’s carpals that were identified during the diagnosis.
• Return to low-level pleasure riding may be possible as moderate MCJ osteoarthritis was seen but without any involvement of the radiocarpal joint, allowing substantial, pain-free carpal flexion.
• The research suggests that early PCA of the MCJ and CMCJ could be a useful alternative treatment for complicated fourth carpal bone fractures, especially when a reconstruction is not possible.