- Types include: apical, midbody, basilar, abaxial, sagittal and comminuted.
- Cause : overload of sesamoid bones within the suspensory apparatus at maximal extension.
- Signs : acute - lameness, swelling, joint effusion, crepitus; chronic - may show few localizing signs.
- Diagnosis : radiography , ultrasound [Ultrasonography: bone joints] [Ultrasonography: musculoskeletal] , scintigraphy , perineural [Hindlimb: perineural analgesia] /-intra articular anesthesia .
- Treatment : depends on fracture type - apical → surgical removal , midbody → lag screw repair or circumferential wiring ; basilar → conservative or arthroscopic surgery [Joint: arthroscopy - overview] ; non-articular fractures → conservative.
- Prognosis : good to poor depending on fracture type.
- See also:
- Moderate to severe lameness (3-5/5) within 24 h of race.
- Weightbearing on toe to avoid tension on palmar fetlock.
- Joint effusion (not if non-articular fracture or recent intra-articular steroids).
- Pain on flexion (not marked, decreases with chronicity).
- Pain on digital palpation of apex of sesamoid (not consistent).
- Chronic: positive response to nerve joint blocks.
- More soft tissue swelling than apical fractures.
- Lameness can be severe.
- Usually non-articular, although articular fractures occur less commonly - joint effusion if articular fracture.
- Soft tissue swelling along palmar or plantar surface.
- Usually articular.
- Soft tissue swelling.
- Pain on flexion.
Comminuted or biaxial fractures
- Non-weightbearing lameness as often associated with suspensory apparatus breakdown.
- Fetlock swelling - fragments of sesamoids often palpable palmarly/plantarly.
- Joint effusion.
- Crepitus on manipulation.
- Hyperextended fetlock.
- Horse may present for more obvious condylar fracture.
- Depends on the size of the fragment and damage to the suspensory apparatus.
- Good - for small apical and basilar fragments.
- Poor - for larger fragments and midbody, sagittal, comminuted or biaxial fractures.
Reasons for treatment failure
- Septic arthritis .
- Implant failure.
- Contralateral limb complications.
- Loss of vascular integrity to distal limb in breakdown injuries.