34th Annual Scientific Meeting proceedings

Equine maxillary and mandibular fractures are common but sporadic, and literature reporting their treatment although widespread, comprises mainly multiple case reports¹, and in vitro biomechanical studies.

Appraisal of head trauma is beyond the scope of this presentation but thorough clinical, neurological, ocular and dental examinations should be included before planning treatments. Diagnostic imaging is possible using radiography but CT is vastly superior if available for fracture planning

Treatments used historically include conservative management, stabilization using cerclage and tension band wiring, narrow DCP and screw fixation, locking plate fixation; external co-aptation, titanium rosettes or a combination of techniques^2-7. In many cases an acceptable result is achieved using conservative management. However, more modern methods of fixation, including traditional internal fixation techniques, and more recent technology that has added the opportunity of lightweight malleable implants, have opened the possibility to better functional and cosmetic repair combined with a potentially shorter convalescent time. Due to advancement of techniques available, and lack of data making direct comparisons, publications comparing techniques are either in-vitro or based on retrospective data. Limitations of traditional methods include: the availability, size, weight and strength of implants; the likelihood of fractures being open; the potential costs of getting the best available outcome; and a conservative attitude to the importance of a functional cosmetic result.

In humans and small animals, titanium conformable LCP plates or synthetic resorbable implants have been the standard for craniofacial trauma for nearly 20 years, more recently utilizing 3-dimensional imaging and 3D printing techniques^{8, 9}.  Such implants have features suited for use in selected equine head fractures. Many fractures of the equine head are non-weight-bearing, which enables using implants that would mechanically fail under higher loads. In addition, the equine skull bone fractures have a greater tolerance to contamination than do limb bone fractures, enabling good outcomes in imperfect conditions for fracture fixation.

In addition to functional fracture repair, careful reconstruction to achieve a cosmetic result should be an aim.  Inadequate repair can result in facial distortion, airway occlusion, intra-nasal or intra-sinus fistulae or persistent draining tracts. 

The use of malleable or absorbable implants to manage head injuries in 7 horses is presented. Cases that underwent stabilisation/fixation of head fractures at B&W Equine hospital from 2017-2025 were analysed. Seven cases with injuries to the skull or mandible that underwent reconstruction in this manner were identified. Cases treated conservatively were excluded. Six cases underwent repair using conformable locking compression plates with self-tapping 3.5mm screws used alone or in combination. One horse underwent repair of a facial defect resulting from previous frontal osteotomy by using a biodegradable polymer implant with ultrasonically activated polymer weld fixation.

Surgical techniques
Surgical planning was undertaken based on clinical appraisal, degrees of comminution, contamination and diagnostic imaging. Open fractures underwent debridement surgically and lavage before implant placement.   Depressed vital fragments were elevated to attempt fracture reduction. Small fragments with no soft-tissue attachment were excised. Titanium polyaxial  locking plates (7-12 holes) were used with 3.5mm self-tapping screws^a. The plates were inserted and positioned using full length incisions or stab incisions with creation of a tunnel using a periosteal elevator, and stab incisions for screw insertion.  Screws were inserted at angles to enable the best screw-thread to bone contact and subsequently locked into the plates.  Screw holes overlying fracture planes were left vacant.  One horse (case 6) underwent repair of a frontal defect using an absorbable polymer plate fixed using ultrasound welded absorbable polymer pins^b. Implants remained in situ after healing, although individual screws were removed from the construct in two cases. Skin incisions were closed using 3mm polyglecaprone. Dressings were placed over plate incisions for 24-48 hours. All cases were radiographed post-operative radiography to assess implant placement. 

The horses ranged in age from 12-20 years and were of a range of breeds and activities and included hacking, retired racehorses and 3* event horses.  All patients had a history of trauma involving the head or mandible, that occurred from <1 day to several months prior to presentation. Signalment included head swelling (soft tissue or non-painful firm swelling), wound exudation or dysmastication in most cases.  All cases, except case 7, underwent CT examination that was undertaken with the horse sedated and standing in five cases, and one that was imaged while anaesthetised, en route to fracture repair.

Treatment and outcomes
Treatments are summarised in table 2.

All fractures were considered to be open, although in case 6, the historical surgically created defect had healed. Four horses underwent repair while anaesthetised and three while standing, sedated and with regional analgesia as determined by the horses’ character and injury location, the configuration of the injury and the likely efficacy of regional analgesia. Sedation was achieved using detomidine in combination with opiate analgesia.  Regional analgesia comprised local infiltration, maxillary or ethmoidal nerve blocks. Where possible, plates were inserted through incisions smaller than the plate or stab incisions to minimise soft tissue trauma and reduce wound dehiscence. Plates were left in situ in call cases. In two cases, discharging tracts persisted and loosened screws were removed. In case 5, the bio-absorbable implant was successfully incorporated although the intra-sinus cyst re-occurred and the horse underwent minimally invasive sinus surgery 12 months later. All cases resumed their previous activities (Case 7 is still convalescing).

Craniofacial titanium and biodegradable polymers offer attractive options for equine craniofacial repair and unstable suture periostitis¹¹. Implants are well-tolerated in contaminated open fractures, and can sometimes be inserted in the conscious patient through minimally-invasive incisions. Stabilisation is effective and smaller implants can be used with newer, innovative constructs, than with than with conventional internal fixation techniques^12,.

1. Vetlox, Freelance Surgical , Wrington, UK.
2. VetWelding AG, Muehlebach 2, Switzerand

References

1. Henninger RW; Beard WL;Schneider RK;; Bramlage LRBurkhardt HA Fractures of the rostral portion of the mandible and maxilla in horses: 89 cases (1979-1997) Journal of the American Veterinary Medical Association [J Am Vet Med Assoc] 1999 Jun 01; Vol. 214 (11), pp. 1648-52
2. Beard, W. (2009), Fracture repair techniques for the equine mandible and maxilla. Equine Veterinary Education, 21: 352-357. 
3. Tremaine W.H. (2004) Management of skull fractures in the horse. In Practice (0263841X); Apr2004, Vol. 26 Issue 4, p214-222
4. Peavey, C.L., Edward, R.B., III, Escarcega, A.J., Vanderby, R., Jr and Markel, M.D. (2003), Fixation Technique Influences the Monotonic Properties of Equine Mandibular Fracture Constructs. Veterinary Surgery, 32: 350-358. Leps, A., Haardt, H., Vanderperren, K., Vlaminck, L. & Martens, A. (2023) Successful treatment of an open incisive bone fracture using a locking compression plate combined with intraoral cerclage wiring. Equine Veterinary Education, 35, e378–e384.
5. Kuemmerle JM;Kummer M; Auer JA; Nitzl D;Fürst AE Locking compression plate osteosynthesis of complicated mandibular fractures in six horses. Veterinary and comparative orthopaedics and traumatology : V.C.O.T [Vet Comp Orthop Traumatol] 2009; Vol. 22 (1), pp. 54-8
6. Henriksson, S., Gorvy, D. & Skärlina, E. (2024) Successful reconstruction of a bilateral comminuted mandibular fracture in a foal using 2.7 locking compression plates. 
7. Nelson BB, Easley J, Steward SKT, et al. Polyaxial pedicle screw external fixation to stabilize oblique mandibular fractures in three standing, sedated horses. Veterinary Surgery. 2021; 50: 659–667.
8. Gareb B, Van Bakelen NB, Vissink A, Bos RRM, Van Minnen B. Titanium or Biodegradable Osteosynthesis in Maxillofacial Surgery? In Vitro and In Vivo Performances. Polymers (Basel). 2022 Jul 7;14(14):2782.
9. Takahiro Kanno; Shintaro Sukegawa; Yoshihiko Furuki; Yoshiki Nariai; Joji Sekine (2018) Overview of innovative advances in bioresorbable plate systems for oral and maxillofacial surgery. Japanese Dental Science Review, Open Access Journals
10. Monck SL, McGilvray KC, Easley JT. Biomechanical comparison of locking compression plate fixation and a novel pedicle screw external fixation to repair equine mandibular fractures. Veterinary Surgery. 2020; 49: 997–1006.
11. Verwilghen, D;Easley, J;Zwick, T; et al (2022) Equine Suture Exostosis: A Review of Cases from a Multicenter Retrospective Study. Veterinary Sciences; Jul2022, Vol. 9 Issue 7, 14.
12. Tomlinson AW; Comerford EJ;Birch RS;Innes JFWalton MB (2015) Mechanical performance in axial compression of a titanium polyaxial locking plate system in a fracture gap model. Veterinary and comparative orthopaedics and traumatology  V.C.O.T [Vet Comp Orthop Traumatol] 2015; Vol. 28 (2), pp. 88-94.

Acknowledgements
Consumables and ultrasonic unit for case 6 loaned by VetWelding AG, Muehlebach 2, CH-6362 Stansstad/NW, Switzerland.