Core decompression of the equine navicular bone: an in vivo study in healthy horses

Objective: To determine the physiologic response of the equine navicular bone to core decompression surgery in healthy horses. Study Design: Experimental in vivo study. Materials: Healthy adult horses (n=6). Methods: Core decompression was completed by creating three 2.5‐mm‐diameter drill channels into the navicular bone under arthroscopic control. The venous (P_V), arterial (P_A), articular (P_DIPJ), and intraosseous pressures (IOP) were recorded before and after decompression drilling. Each IOP measurement consisted of a baseline (IOP_B) and a stress test (intramedullary injection of saline solution, IOP_S) recording. Lameness was assessed subjectively and using force plate gait analysis. Fluorochrome bone labeling was performed. Horses were euthanatized at 12 weeks. Navicular bone mineral density (BMD) was measured, and bone histology evaluated. Results: Peak IOP (IOP_max) after stress testing was significantly (P<.05) reduced immediately after core decompression; however, the magnitude of these effects was decreased at 3 and 6 weeks after decompression. A significant (P<.05) correlation existed between IOP_max and BMD. No lameness was observed beyond the first week after surgery. Substantial remodeling and neovascularization was evident adjacent the surgery sites. Conclusion: Navicular bone core decompression surgery reduced IOP_max, and, with the exception of a mild short‐lived lameness, caused no other adverse effects in healthy horses during the 12‐week study period.