Incomplete Ossification Humeral Condyle (IOHC)
At birth, the two humeral condyles are connected by a fibrotic band, that fuses (complete ossification) between 8 and 12 weeks of age. Failing of the ossification results in a permanent fissure between the two condyles (incomplete ossification).
This pathology is called Incomplete Ossification of the Humeral Condyle (IOHC), and commonly affects Spaniels but also Labrador, Pointer, Rottweiler, German Shepperd, and Yorkshire Terrier.
The fissure is often bilateral (in both elbows) and results in weakness of the elbow joint. During the exercise, the loading of the weight on the elbow joint causes micromovement between the condyles resulting in pain and lameness. In the most severe cases, or following jumping or intense exercise, the micromovements may cause a fracture of the elbow.
Diagnosis
IOHC can be diagnosed on XR, where the fissure is seen as a very thin line between the condyles. However, sometimes this is not visible on XR; in this case, either CT or arthroscopy exam may be required.
The red circle highlights a thin (radiolucent) black line between the condyle. The black line shows the lack of bone between the condyles (fissure).
Normal Elbow
Treatment
Medical treatment could be often associated with a fracture of the hummers; therefore, surgical treatment is commonly considered the treatment of choice.
A trans-condylar screw is placed between the two condyles and this should be as large as possible to reduce as much as possible the risk of screw rupture due to fatigue failure.
Complications
Infection, seroma (post-operative swelling), and fatigue rupture of the screw are the most common complications.
Whereases seroma resolves within a few weeks, rupture of the screw requires a review surgery. Our surgical choice is to use as large a trans-condylar screw as possible, to avoid or reduce the risk of implant failure.
Infections are treated with antibiotics; however, if antibiotics are not enough a further surgery may be required.
Case studies
Postoperative XR Mediolateral View
Fracture
Patient: Dog
Typology: IOHC
Repairing Method: A screw 4.5mm was placed in lag fashion between the two condyles
Pre-opertive XR,
Post operative XR craniocaudal view
Lameness was detected on the left thoracic limb
A few months after surgery