Incomplete Ossification of the Humeral Condyle (IOHC)
Incomplete ossification of the humeral condyle (IOHC) is also known as humeral intracondylar fissure (HIF) or Humeral Condylar Fiissure (HCF). IOHC is a congenital condition in which there is a weakness in the humeral condyle (part of the elbow). It is most commonly seen in spaniels, especially Springer Spaniels in the UK. This condition predisposes to fractures of the humeral condyle and can also cause lameness without fracture. Some dogs show no signs at all and so an owner may not know their dog has the condition. There may be a genetic basis to the condition.
The end of the upper arm bone (humerus) looks like this:
The cartilage between the bone at the bottom of the arm (under the hole) goes through a process called ossification. Ossification is the term for forming new bone. The bone should replace the cartilage completely with no gaps by the time the dog is 4 months old. In IOHC, the bone does not completely form properly within this area.
Humeral intracondylar fissure (HIF) is the same area of weakness in the elbow but develops in older dogs. Dogs that have normal elbows as a puppy can go on to develop a stress fracture in this area that can lead to an elbow fracture with minimal trauma. This is why the condition is now more commonly called Humeral Condylar Fiissure (HCF).
Knowledge of IOHC is limited and the average age of diagnosis is 3-4 years. It is unknown why these stress fractures happen and why spaniel breeds seem to be predisposed. IOHC can not be easily detected by XRay as it is found within the humerus, between the lateral and medial condyles. Only around 60% of IOHC cases may be detected by a faint white line on an XRay whereas over 90% of elbows with IOHC will have degenerative changes in addition to the IOHC that could be responsible for the lameness. IOHC is often diagnosed secondary to a fracture following minimal trauma.
The picture with the screw through is the elbow fixation. The level where the screw has been placed is the angle of the CT scan revealing the fissure (hole) within that part of bone. The green circle indicates a slice of the lower arm and within it, the red arrow points to the hole (black dot).
Clumber Spaniel Health is working with Embark to research this condition. If your dog has diagnosed IOHC, HCF or HIF, please email us at email@example.com. We will send you a free testing kit (mouth swab) for your dog and a link for the Embark website for you to enter your dogs details. We would just require your name and address for postage. Embark will batch test all samples once they have enough and you will receive your results at that point (it may be some time!). Embark are exploring a genetic link between dogs that have been affected with the condition. If a link is found then it can be tested for and then we will be able to breed away from the condition.
Prevalence of incomplete ossification of the humeral condyle and other abnormalities of the elbow in English Springer Spaniels - A. P. Moores, P. Agthe, I. A. Schaafsma
Epidemiology and clinical management of elbow joint disease in dogs under primary veterinary care in the UK - D.G. O'Neill, D. C. Brodbelt, D.B. Church, R. L. Meeson
Treatment of Incomplete Ossification of the Humeral Condyle with Autogenous Bone Grafting Techniques - N. Fitzpatrick, T. J. Smith, J. O'Riordan, R. Yeadon