Sesamoid: developmental malformation

• Cause: developmental malformation of the plantar or palmar sesamoid bones. May arise from multiple centers of ossification. Included under the general heading sesamoid disease in some texts.
• Signs: generally asymptomatic: usually incidental finding on radiography of the pes. More commonly found in the manus.
• Diagnosis: radiography. The sesamoid can be bipartite or multipartite.
• Treatment: if lame: rest and analgesia.
• Prognosis: good.

• Generally incidental finding on radiographs of the pes or manus.
• Occasionally displace causing pain on direct palpation and on flexion of the digits.

• Incidental finding when radiographed for another reason, so identified at any age.
• Assumed to be developmental, so probably occurs at stage of ossification of the sesamoid bones.

• Rottweiler Rottweiler.
• Greyhound Greyhound.

• If problems arise they often resolve with rest and analgesia.

• Two possible mechanisms suggested:
  • Multiple centers of ossification that failed to unite; or
  • Incomplete ossification of cartilage template.
• Sesamoid bones 2 and 7 most commonly affected, numbering medial to lateral. This is thought to be from pressure from the overlying flexor tendons during hyperextension as the metacarpo/metatarso-phalangeal joints 2 and 5 are slightly outwardly rotated.

• Developmental disorder, detailed pathogenesis unknown.

• Sesamoid bones located in tendon of insertion of the interosseous muscles at the metacarpo-phalangeal joints.
• Multiple centers of ossification during development may result in multipartite or bipartite sesamoid bone formation.
• Incomplete ossification of a cartilage template would also be a possible etiology.
• Restriction of vascular foramina in sesamoids 2 and 7 was found in dogs with sesamoid disease and not in clinically normal dogs.
• There is an over-representation in the right manus of the racing Greyhound suggesting a traumatic component.

• Usually asymptomatic.
• May manifest as pain on manipulation of the foot.

• Incidental finding on radiography, generally no lameness.
• Occasionally displaced causing discomfort and pain on direct palpation.

• See radiography of the manus Radiography: carpus and forefoot and pes Radiography: tarsus and hindfoot.
• Differentiate from fractures radiographically:
  • A fracture has a sharp, irregular well-defined fragment outline   ; bipartite sesamoids have smooth outlines  .
• Differentiate from degenerative disease radiographically:
  • Degenerative disease has pain on palpation, joint swelling or thickening, calcified periarticular bodies and osteophytosis.

• Sesamoiditis Sesamoid: disease.
• Sesamoid fracture Sesamoid: fracture.

• No treatment in most cases.
• If painful, rest and anti-inflammatory treatment Analgesia: NSAID in the acute stage resolves most cases.
• Chronic painful cases, consider surgical removal of the painful sesamoid bone.

Monitoring

• If acutely painful, radiography to monitor any secondary degenerative change development.
• Conservative management: monitor lameness related to pain on direct palpation → should resolve in 4-6 weeks.
• Asymptomatic: no further monitoring or treatment needed.

• Good.

• If painful, surgical excision indicated if lameness persists after conservative management.
• In the long term surgical treatment has been shown to be no better than conservative management.
• Incidental finding on survey radiographs: no treatment needed - no further monitoring required.

• Incorrect diagnosis. Eliminate other causes of lameness especially elbow dysplasia in young Rottweilers Elbow: dysplasia.
• Osteoarthritis of the metacarpo/metatarso-phalangeal joint Arthritis: osteoarthritis.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Harasen G (2009) Sesamoid disease. Can Vet J 50 (10), 1095 PubMed.
• Daniel A, Read R A & Cake M A (2008) Vascular foramina of the metacarpophalangeal sesamoid bones of Greyhounds and their relationship to sesamoid disease. Am J Vet Res 69 (6), 716-721 PubMed.
• Vaughan L C & France C (1986) Abnormalities of the volar and plantar sesamoid bones in Rottweilers. JSAP 27 (9), 551-8 VetMedResource.
• Bennett D & Kelly D F (1985) Sesamoid disease as a cause of lameness in young dogs. JSAP 26 (10), 567-79 VetMedResource.
• Bateman J K (1959) Fractured sesamoids in the greyhound. Vet Rec 71, 101.

Other sources of information

• Robins G M & Read R A (1998)diseases of the sesamoid bones.In:Canine Sports Medicine and Surgery.Bloomberg M S, Dee J F & Taylor R A (eds). Saunders W B Company, Philadelphia, pp 255-264.
• Robins G E & Read R A (1993)diseases of the sesamoid bones.In:Disease mechanisms in small animal surgery.pp 1094.