Fragmented coronoid process

From Dog
Fragmnted coronoid process in a German Shepherd dog[1]

Fragmented coronoid process (loose processus coronoideus) is a common genetic disease of the coronoid process of the canine elbow resulting in elbow dysplasia, osteoarthritis and lameness[2].

This condition is usually associated with severe elbow incongruity and characterized by a distracted coronoid fragment abrading the adjacent humeral cartilage, causing arthritis and pain[3].

The cause(s) of this disease are numerous such as genetic predisposition, over-nutrition and heavy exercise while young, leading to unusual weight-bearing on an eccentrically-deformed and immature joint[4]. Trauma may also cause this disease, and has been reported in toy-breeds[5].

Like osteochondritis dissecans, fragmented coronoid process is observed in fast growing large-breed dogs such as the Rottweiler, Golden Retriever, St. Bernard, Bernese Mountain Dog, Newfoundland and German Shepherd[6].

The medial coronoid process of the distal elbow joint consists of cartilage until the 4 -5 months of age, when ossification starts. During this period it is very sensitive to stress. Frequently both front legs are affected. Most of the affected dogs show a higher bodyweight compared to other puppies of the same age ( weight about 17-25 kg and higher), and males are more commonly affected.

The development of OCD and/or FCP is promoted by overnutritition (high protein, high energy, additional supply of minerals, Ca++) because the genetic predisposition for fast growing will be used and disturbances of enchondral ossification becomes more likely. Dogs with early exercise are more often affected.

Clinical signs are often apparent by 7 - 8 months of age and include lameness, decreased joint movement during manipulation of the elbow joint, pain and joint effusion.

Diagnosis is usually confirmed by radiography, which can be difficult due to superimposition of the joints of the elbow and may required varying angle shots or use of CT scans[7].

Osteophytes and osteosclerosis are good indicators of disease, best visualized on a flexed lateral view, especially at the proximal aspect of the anconeal process. Craniocaudal views show lipping and osteophytosis in the region of the medial coronoid process and epicondyles. Other radiographic signs include abnormal shape of the joint, sclerosis and lucency affecting the medial coronoid process, subchondral sclerosis of the ulna and humerus and irregular radial incisure of the ulna[8].

A differential diagnosis would include osteochondrosis, osteomyelitis, osteochondritis dissecans, ununited anconeal process, panosteitis and hypertrophic osteodystrophy.

Medical treatment (e.g. carprofen, meloxicam) may be advised in cases with intermittent lameness. Dietary restrictions appear to have limited ability in corecting teh developing inflammatory joint disease[9].

Surgical removal of the fractured coronoid process is usually recommended, but is not without disadvantages[10].

The prognosis is guarded since dogs with fragmented coronoid process invariably develop varying degrees of osteoarthrosis of the elbow joint despite conservative or surgical treatment.


  1. Phillipe Duponant
  2. Temwichitr J et al (2010) Fragmented coronoid process in the dog: a heritable disease. Vet J 185(2):123-129
  3. Samoy Y et al (2012) Arthroscopic Findings in 32 Joints Affected by Severe Elbow Incongruity with Concomitant Fragmented Medial Coronoid Process. Vet Surg Mar 5
  4. Burton NJ et al (2010) Comparison of bone mineral density in medial coronoid processes of dogs with and without medial coronoid process fragmentation. Am J Vet Res 71(1):41-46
  5. Hadley HS et al (2009) Traumatic fragmented medial coronoid process in a Chihuahua. Vet Comp Orthop Traumatol 22(4):328-331
  6. Hartmann P et al (2012) Multivariate prediction of breeding values for canine hip and elbow dysplasia as well as humeral osteochondrosis in the Bernese mountain dog. Berl Munch Tierarztl Wochenschr 125(9-10):432-440
  7. Samoy Y et al (2012) Computed tomography findings in 32 joints affected with severe elbow incongruity and fragmented medial coronoid process. Vet Surg 41(4):486-494
  8. Groth AM et al (2009) Spectrum of computed tomographic findings in 58 canine elbows with fragmentation of the medial coronoid process. J Small Anim Pract 50(1):15-22
  9. Huck JL et al (2009) A longitudinal study of the influence of lifetime food restriction on development of osteoarthritis in the canine elbow. Vet Surg 38(2):192-198
  10. Bouck GR et al (1995) A comparison of surgical and medical treatment of fragmented coronoid process and osteochondritis dissecans of the canine elbow. Vet Comp Orthop Traumatol 8:177-183