• Midbody fractures of the proximal sesamoid bones Proximal sesamoid: fracture require internal fixation to achieve a bony union and to restore the function of the suspensory apparatus and fetlock joint.
• Constant tension on the fracture line by the suspensory apparatus → instability with poor healing, often fibrous union and chronic pain in midbody fractures unless internal fixation is used.
• Initially a circumferential transfixation wiring technique was reported but this was found to be associated with high postoperative morbidity and complications of wire slippage and breakage. Subsequently, a hemicircumferential wiring technique was published and this is the technique reported here. Initially this was via an open technique but recently an endoscopic guided technique has been published.

Approaches

• Arthroscopic: via the palmar/plantar pouch of the fetlock joint and the proximal digital flexor tendon sheath Fetlock: arthroscopy.
• Arthrotomy: of the palmar/plantar fetlock joint and synoviotomy of the digital flexor tendon sheath via desmotomy of the palmar/plantar annular ligament.

• Mid-body fractures of the proximal sesamoid bone not amenable to other forms of surgical fixation Proximal sesamoid bone: fracture repair – lag screw.

Advantages

• Improves fracture stability → bony union and restoration of suspensory apparatus function.
• Requires no special equipment.
• Technically less demanding than lag screw fixation Proximal sesamoid bone: fracture repair – lag screw but requires good anatomical knowledge.

Disadvantages

• Can be difficult to achieve good apposition and stable reduction.
• Less stable than lag screw technique Proximal sesamoid bone: fracture repair – lag screw leading to fracture distraction, gap formation and consequently worse prognosis for successful repair.
• Requires longer period of cast immobilization than lag screw fixation.
• Possible irritation of the tendon sheath, wire migration and impingement on adjacent soft tissues.

• Conservative treatment Proximal sesamoid: fracture.
• Surgical removal Proximal sesamoid: fracture – arthroscopic removal of very small fragments.
• Lag screw fixation Proximal sesamoid bone: fracture repair – lag screw.
• Cast immobilization.

Preparation

• General anesthesia induction and maintenance: 20 min.
• Aseptic preparation: 10 min.

Procedure

• Surgery (including bone grafting): 60-70 min.
• Cast application: 20-30 min Musculoskeletal: external fixation – casts.

Criteria for choosing test/procedure

• Complete assessment of case Proximal sesamoid: fracture with use of radiography Forelimb: radiography to determine fracture type and ultrasound Ultrasonography: flexor tendon to assess soft tissue suspensory apparatus damage.
• Other injuries of fetlock region may be present.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Busschers E, Richardson D W, Hogan P M et al (2008) Surgical repair of mid-body proximal sesamoid bone fractures in 25 horses. Vet Surg 37 (8), 771-780 PubMed.
• Rothaug P G, Boston R C, Richardson D W et al (2002) A comparison of ultra-high-molecular weight polyethylene cable and stainless steel wire using two fixation techniques for repair of equine midbody sesamoid fractures: an in vitro biomechanical study. Vet Surg 31 (5), 445-454 PubMed.
• Woodie J B, Ruggles A J & Litsky A S (2000) In vitro biomechanical properties of 2 compression fixation methods for midbody proximal sesamoid bone fractures in horses. Vet Surg 29 (4), 358-363 PubMed.
• Martin B B, Nunamaker D M, Evans L H et al (1991) Circumferential wiring of mid-body and large basilar fractures of the proximal sesamoid bone in 15 horses. Vet Surg 20, 9-14 PubMed.

Other sources of information

• Wright I M (2020) Fractures of the Proximal Sesamoid Bones. In: Equine Fracture Repair. Ed: Nixon A J. Wiley Blackwell, USA. ISBN 9780813815862.