Equine bone cysts: What do we know about them and their treatment?

Equine bone cysts and bisphosphonates

“…I enjoyed your clinical commentary in the March issue of EVE on equine bone cysts (Bonilla 2021); however, I am concerned with some of the text describing bisphosphonate use. The safety of bisphosphonates as a class of drug is a discussion that should be addressed through research upon which we both agree.…”

Treatment of osseous cyst‐like lesions

“…Osseous cyst‐like lesions (OCLL) are focal, radiolucent areas with a sclerotic rim and a dome, conical or spherical shape typically located within the epiphyseal trabecular bone adjacent to a weight‐bearing area of the articular surface (Jeffcott et al 1983; von Rechenberg et al 1998; Sherlock and Mair 2011; Denoix et al 2013; Balducci et al 2019; Bonilla 2019). Most OCLLs communicate with the joint through tracts of varying sizes.…”

“…Osseous cyst‐like lesions, which were traditionally called subchondral bone cysts, are the most common of the three types of bone cysts recognised in the horse, which also include the rarely reported aneurysmal and unicameral bone cysts (von Rechenberg et al 1998; Sherlock and Mair 2011; Denoix et al 2013; Stöcker et al 2017; Balducci et al 2019; Bonilla 2019). While aneurysmal and unicameral cysts are true bone cysts, which are defined as closed cavities lined by epithelium, OCLLs lack an epithelial lining and usually have articular communication and thus are more appropriately termed osseous/subchondral cyst‐like lesions (Sherlock and Mair 2011; Bonilla 2019).…”

“…Osseous cyst‐like lesions, which were traditionally called subchondral bone cysts, are the most common of the three types of bone cysts recognised in the horse, which also include the rarely reported aneurysmal and unicameral bone cysts (von Rechenberg et al 1998; Sherlock and Mair 2011; Denoix et al 2013; Stöcker et al 2017; Balducci et al 2019; Bonilla 2019). While aneurysmal and unicameral cysts are true bone cysts, which are defined as closed cavities lined by epithelium, OCLLs lack an epithelial lining and usually have articular communication and thus are more appropriately termed osseous/subchondral cyst‐like lesions (Sherlock and Mair 2011; Bonilla 2019). Osseous cyst‐like lesions in horses are most commonly found in males (62%) in the medial condyle of the femur (45.8%), followed by phalanges (26.2%), carpal bones (7.1%), metacarpal and metatarsal bones (6%), tibia (4.4%), radius (3%), talus, sesamoid bones, humerus, patella, scapula and tarsal bones (von Rechenberg et al 1998).…”

“…Osseous cyst-like lesions in horses are most commonly found in males (62%) in the medial condyle of the femur (45.8%), followed by phalanges (26.2%), carpal bones (7.1%), metacarpal and metatarsal bones (6%), tibia (4.4%), radius (3%), talus, sesamoid bones, humerus, patella, scapula and tarsal bones (von Rechenberg et al 1998). They can be an incidental finding but often are associated with variable degrees of lameness ranging from mild to severe with an insidious or acute onset (Bonilla 2019).…”