34th Annual Scientific Meeting proceedings

Standing orthopaedic surgery is regularly performed in horses for a variety or reasons (1). Reasons for this include to avoid the risks associated with general anaesthesia, to avoid the need for specialised equipment/facilities associated with surgery performed under general anaesthesia, to reduce costs, to allow multiple surgeries to be carried out concurrently in busy hospitals.

When deciding to perform a surgery standing a number of questions need to be asked. Am I performing the surgery standing for the right reasons? Is it easier to perform the surgery standing or anaesthetised? Is it safe for the patient and operating team to perform the surgery standing? Can I do as good a job, if not better, with the horse standing rather than anaesthetised? Will the outcome be jeopardised or enhanced by performing the surgery standing?

Generally I try to avoid doing surgery standing if its solely motivated by reducing the costs. For example in my experience the expertise required to perform a fracture repair with the horse standing, coupled with the additional risk carried by the operating team, preclude a cost reduction when compared to performing the same surgery under general anaesthesia. Clients being motivated to have a surgery performed with their horse standing as a cost saving measure should be avoided.

For the purposes of this talk I will be focusing on the types of cases I typically perform surgery on with the patient standing. Again safety of the operating team is a priority. Appropriate sedation and restraint of the horse is necessary in all cases and the team involved should have a good understanding of the various steps of the procedure. I like to wear a safety helmet when performing regional anaesthesia prior to surgery and I wear the helmet when performing the surgery as well.

Standing fracture repair
Many incomplete fractures of the third metacarpal/metatarsal bones and proximal phalanx (P1) are amenable to repair with the horse standing and sedated (2,3,4). Simple non-displaced fractures of the distal cannon bone and proximal phalanx are easily repaired with the horse standing and it is a relatively quick and efficient procedure to perform. Other more complex fractures such as proximally propagating/spiralling fractures of the distal cannon bone carry a risk of catastrophic failure during recovery from anaesthesia and my preference is to repair this fracture configuration with the horse standing. While repair of other fracture configurations, such as those of the ulna/olecranon, are described (5) I have not repaired these fractures in the standing horse.

Implant Removal
Transphyseal implants, placed for the correction of angular limb deformities in juvenile thoroughbreds, can be easily removed with the patient standing. Following routine surgical preparation of the surgery site local infiltration of the surgery site allows removal of the implant through a stab incision created directly over the head of the implant. While placement of transphyseal screws in the standing animal has been descried (6) it is not a procedure I perform. When the implant has been placed on the medial aspect of the leg I typically remove the implant under general anaesthesia.
Following repair and subsequent healing of fractures of the distal cannon bone or proximal phalanx it may be necessary to remove the implants for a variety of reasons. Again this is well tolerated in the standing horse. In some instances bony proliferation around the implants, particularly in P1, make implant removal a little more challenging and removal under general anaesthesia is preferable.

Sequestrum removal
Many sequestra of long bones are amenable to removal in the standing horse and surgery, following appropriate desensitisation of the site with local anaesthetic, is well tolerated by the patient.

Conditions of the Foot
Removal of sequestra from the pedal bone or debridement of necrotic pedal bone is easily performed with the horse standing. Additionally hoof wall keratomas can also be removed with the horse standing. Regional anaesthesia at the level of the proximal sesamoid bones and application of a tourniquet followed by surgical preparation of the foot are all that is required.

Cast Appliction
Application of casts to the distal limb for the purposes of immobilisation for wound healing or following fracture repair is well tolerated in the standing horse. In my experience I am less likely to get complications associated with cast immobilisation when a cast is applied with the horse standing versus anaesthetised.

References

1. O'Brien T, Hunt RJ. Recent advances in standing equine orthopedic surgery. Vet Clin North Am Equine Pract. 2014 Apr;30(1):221-37. doi: 10.1016/j.cveq.2013.11.006. Epub 2014 Jan 25. PMID: 24680214.
2. Russell TM, Maclean AA. Standing surgical repair of propagating metacarpal and metatarsal condylar fractures in racehorses. Equine Vet J. 2006 Sep;38(5):423-7. doi: 10.2746/042516406778400664. PMID: 16986602.
3. Perez-Olmos, J.F., Schofield, W.L., Mcgovern, F., Dillon, H. and Sadlier, M. (2006), Standing surgical treatment of spiral longitudinal metacarpal and metatarsal condylar fractures in 4 horses. Equine Veterinary Education, 18: 309-313.
4. Payne RJ, Compston PC. Short- and long-term results following standing fracture repair in 34 horses. Equine Vet J. 2012 Nov;44(6):721-5. doi: 10.1111/j.2042-3306.2012.00569.x. Epub 2012 Apr 17. PMID: 22506811.
5. Jimenez-Rihuete, P. & O’Meara, B. (2023) Three cases of olecranon fracture repair in the standing horse. Equine Veterinary Education, 35, e 193–e 199
6. Modesto RB, Rodgerson DH, Masciarelli AE, Spirito M. Standing placement of transphyseal screw in the distal radius in 8 Thoroughbred yearlings. Can Vet J. 2015 Jun;56(6):605-9. PMID: 26028683; PMCID: PMC4431159.