Experimental comparison of caudal wedge ostectomy to cranial wedge ostectomy for surgical treatment of overriding/impinging spinous processes in horses.
Authors: Connaughton Maurice Thomas, MacDonald Eilidh Janet, Ireland Jo L, Rocchigiani Guido, Stack John David
Journal: Equine veterinary journal
Summary
# Editorial Summary Overriding and impinging spinous processes (SPs) remain a source of back pain in horses, yet the optimal surgical approach has never been definitively established. Researchers compared two wedge ostectomy techniques—the established cranial wedge method against a novel caudal wedge approach—by performing cadaveric surgery and then analysing radiographs from 67 horses with naturally occurring SP impingement, calculating bone removal, exit angles, and surgical feasibility across different SP inclinations. The caudal wedge ostectomy proved technically straightforward with no operative errors recorded during cadaveric work. More significantly, this technique removed substantially less bone tissue relative to SP width in both caudally and cranially inclined spines (median reduction of approximately 44–40% depending on SP orientation), whilst achieving exit angles much closer to perpendicular—a critical factor for clean, controlled cuts. For caudally inclined processes specifically, the caudal wedge approach reduced the risk of "never-ending-cuts" (incomplete ostectomies that fail to exit the bone) from 96% down to 38%, a clinically meaningful improvement that could reduce operative time and tissue trauma. These findings suggest caudal wedge ostectomy warrants further clinical investigation, particularly for horses with caudally inclined processes where the technique demonstrates clear advantages in bone conservation and surgical precision. Farriers and veterinarians managing horses with dorsal back pain attributed to SP impingement should monitor emerging literature on this approach, as it may ultimately offer a less invasive alternative to conventional cranial wedge methods in suitable cases.
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Practical Takeaways
- •Caudal wedge ostectomy offers a technically feasible alternative to cranial wedge ostectomy for treating overriding spinous processes, particularly in caudally inclined cases
- •The technique preserves more bone while achieving better perpendicular exit angles, potentially reducing complications and tissue trauma
- •Further clinical investigation is needed before widespread adoption, but initial evidence suggests caudal wedge ostectomy may improve success rates and reduce surgical difficulty in horses with caudally inclined impinging spinous processes
Key Findings
- •Caudal wedge ostectomy was feasible with no surgical errors recorded in cadaver study
- •Caudal wedge ostectomy removed significantly less bone than cranial wedge ostectomy (median area/SP width 14.32 vs 25.57 in caudally inclined SPs, p<0.001)
- •Caudal wedge ostectomy produced more perpendicular exits from spinous processes with smaller deviation from 90° (34.77° vs 67.54° in caudally inclined SPs, p<0.001)
- •Caudal wedge ostectomy resulted in fewer never-ending-cuts in caudally inclined spinous processes (37.6% vs 96.2%, p<0.001) but showed no significant difference in cranially inclined cases (76.8% vs 84.3%, p=0.06)