Experimental comparison of caudal wedge ostectomy to cranial wedge ostectomy for surgical treatment of overriding/impinging spinous processes in horses

Connaughton, MT ORCID: 0009-0001-5060-0691, MacDonald, EJ ORCID: 0009-0009-2576-0309, Ireland, JL ORCID: 0000-0002-5737-1502, Rocchigiani, G ORCID: 0000-0002-3742-7636 and Stack, JD ORCID: 0000-0003-0064-7923 (2025) Experimental comparison of caudal wedge ostectomy to cranial wedge ostectomy for surgical treatment of overriding/impinging spinous processes in horses Equine Veterinary Journal, 57 (5). pp. 1395-1404. ISSN 0425-1644, 2042-3306

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Abstract

Background: Caudal wedge ostectomy has not been investigated for overriding or impinging spinous processes (SPs). Objectives: To establish the feasibility of caudal wedge ostectomy and compare measures of surgical trauma and error between hypothetical caudal and cranial wedge ostectomies on SPs of different inclinations. Study Design: Experimental, method comparison study. Methods: Computed tomography and caudal wedge ostectomy surgery were performed on four cadavers. Observations, technical difficulties, and surgical errors were recorded. Radiographs from 67 horses with overriding/impinging SPs were reviewed. Hypothetical ‘ideal’ caudal and cranial wedge ostectomies, and ‘error’ ostectomies 12° from ideal, were drawn at sites of impingement. Ostectomy area/SP width, ostectomy length/SP width, absolute difference of exit angles (angle ostectomy exits the SP) from 90°, and number of error ostectomies failing to exit the SP (never-ending-cuts [NEC]) were calculated. Continuous variables were compared between techniques in caudally and cranially inclined SP groups using Wilcoxon signed-rank tests. Proportions of NEC were compared using McNemar's tests. Results: No surgical errors were recorded with caudal wedge ostectomy. Median ostectomy area/SP width was lower for caudal versus cranial wedge ostectomy in caudally (14.32, interquartile-range [IQR] 9.72–20.34 vs. 25.57, IQR 17.74–33.06; p < 0.001) and cranially inclined SP groups (11.78, IQR 7.98–17.19 vs. 19.62, IQR 13.65–28.68; p < 0.001). Median difference in exit angles from 90° was smaller for caudal versus cranial wedge ostectomies in caudally (34.77°, IQR 26.85°–45.91° vs. 67.54°, IQR 58.13°–74.55°; p < 0.001) and cranially inclined SP groups (49.14°, IQR 35.61°–59.33° vs. 62.84°, IQR 55.34°–70.61°; p < 0.001). The proportion of NEC was lower for caudal versus cranial wedge ostectomy in caudally (37.6%, 95% confidence interval [CI] 29.4%–45.8%; n = 50/133 vs. 96.2%, 95% CI 93.0%–99.5%; n = 128/133; p < 0.001), but not in cranially inclined SP groups (76.8%, 95% CI 70.9%–82.7%; n = 152/198 vs. 84.3%, 95% CI 79.3%–89.4%, n = 167/198; p = 0.06). Main Limitations: Potential bias drawing ‘ideal’ ostectomy. Conclusions: Experimentally, caudal wedge ostectomy was feasible, removed less bone, and resulted in fewer NEC in caudally inclined SPs. Further investigation of the technique is warranted.

Item Type:	Article
Uncontrolled Keywords:	Animals, Horses, Spinal Diseases, Horse Diseases, Cadaver, Tomography, X-Ray Computed, Osteotomy, Female, Male
Divisions:	Faculty of Health & Life Sciences Faculty of Health & Life Sciences > Inst. Infection, Vet & Ecological Sciences
Depositing User:	Symplectic Admin
Date Deposited:	28 Mar 2025 13:31
Last Modified:	23 Jan 2026 00:01
DOI:	10.1111/evj.14498
Open Access URL:	https://doi.org/10.1111/evj.14498
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3191115
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