I’ve spent most of my professional life in areas where English Springer Spaniels are hugely popular (the west country and Hampshire). As a consequence I’ve seen a lot of dogs with what we used to call incomplete ossification of the humeral condyle (IOHC) and now call humeral intracondylar fissure (HIF). This means I’ve also seen a lot of dogs with humeral condylar (elbow) fractures related to this condition.

Humeral intracondylar fissure has always fascinated me. Over the years I’ve published a number of research papers on the condition, more than anyone else world-wide,  and I am now regarded as an expert on the condition. I’ve been invited to lecture on this condition at major conferences and in 2020 I was asked to write a review of HIF for the prestigious Veterinary Clinics of North America. In very basic terms HIF is a fissure (crack) in the humeral condyle (the part of the humerus that contributes to the elbow). The presence of the fissure weakens the condyle. This can cause lameness in its own right but also predisposes dogs to complete condylar fracture. HIF may be partial (not completely crossing the condyle) or complete (crossing the condyle fully) and the former may progress to the latter.  Although it can affect many different breeds, it is most often seen in spaniels and particularly English Springer Spaniels.

2D coronal CT scan (left) and 3D reconstruction with part of the condyle removed (right) of a humeral intracondylar fissure (arrow)
Postoperative x-ray showing placement of a 5.0 locking screw across a HIF

The origins of Humeral Intracondylar Fissure 

The history of HIF is really interesting. For a start, it’s only been recognised relatively recently. For a long time we knew that spaniels were prone to fractures of the humeral condyle and these often occurred during normal activity, but we did not know why. It was only in 1989 that HIF was first described in 4 dogs and then in 1994 it was described in more detail. This was when the term incomplete ossification of the humeral condyle was coined.

In the 2000s HIF would regularly be a topic of heated discussion at orthopaedic meetings. Placing a screw across the humeral condyle to bridge the fissure was widely accepted as the treatment of choice. Yet it seemed that every surgeon had their own preference for which type of screw to place and how to place it (to some extent this remains the case!). And everyone recognised that despite our best efforts, for what should be a relatively simple surgery, there was a high complication rate. Most commonly these would be wound complications and infections, which could drag on for months. I still remember the name of one dog from over 20 years ago because I saw it back so many times trying to resolve its complication! Fortunately, we now know that with the correct surgical approach and an appropriate implant we can reduce the risk of complications dramatically. In the right hands HIF surgery can have a complication rate comparable to other surgeries.

How to diagnose Humeral Intracondylar Fissure

HIF can be difficult to diagnose with x-rays, hence why it went unrecognised for so long. I’ve been working with CT since 2002 and our understanding of HIF has developed alongside greater access to CT imaging. CT is now indispensable for the diagnosis of HIF and for surgical-planning. CT has helped our understanding of what causes HIF. The term IOHC was coined in 1994 because it was thought that HIF was a developmental problem -i.e. a failure of normal development of the humerus in puppies as they grow. Sequential CT scans have shown us, that at least in most dogs, HIF is a type of stress-fracture that develops over time in predominantly adult dogs. Hence the change of name from IOHC which implies a developmental cause, to HIF which simply describes the lesion.

HIF does not always cause symptoms and it will not always progress to complete fracture of the condyle. My research has identified HIF in 14% of normal English Springer Spaniels -those with no history of forelimb lameness. Additional research followed non-symptomatic dogs with HIF that did not have surgery. We showed that 18% of dogs went on to develop complete fractures of the humeral condyle; i.e. not every dog diagnosed with HIF is going to have a problem. Unfortunately, we don’t yet have a way of identifying which dogs will go on to fracture or which will not. By continuing to track these cases with CT I am hopeful that we can change that.

So how do we treat dogs with HIF and counsel their owners?

Firstly, if a dog has a complete fracture of the humeral condyle, whether associated with pre-existing HIF or not, they will always need surgery to reconstruct the condyle. Being part of the elbow, it is important that the condyle is reconstructed as accurately as possible to mitigate the risk of arthritis. The more accurately the condyle is reconstructed, the less severe the arthritis will be over the longer term, so this is definitely a situation where experience and expertise pay huge dividends.

If a dog has a HIF diagnosed in the absence of a complete fracture and it is causing lameness and pain, then we will advise surgery. Surgery will invariably be placement of a large screw across the humeral condyle. When performed well this carries a good prognosis for improving the lameness with a low complication rate. It is important that an appropriate implant is used and that this is placed accurately, and this is where experience and expertise pay dividends again. The implant needs to be relatively large -too small and it may break- but the condyle is relatively small. Accurate placement is critical!

Where HIF is diagnosed in a dog without any symptoms then we counsel each owner on the risk of fracture (18%) and the pros and cons of surgery. Some owners will prefer to ‘wait and see’ and in these cases we will advise CT follow-up of the fissure in 4-6 months. Others will prefer the greater certainty that screw placement gives in avoiding a complete fracture.

Looking forward

And what about the future? Our understanding of this condition has increased hugely over the past 10-15 years but there is still a lot we don’t know. We don’t know why some dogs develop this stress-fracture and others do not. It is likely that the shape (congruity) of the elbow joint plays a role here, but this is not well understood at all. Some surgeons have started to trial surgeries which change the congruity of the elbow (ulnar osteotomy) but these surgeries are not without risk.  Dogs will be a lot more painful after this type of surgery than after screw placement. Furthermore, they remain at risk of condylar fracture (and some will fracture) and the aftercare is much more restrictive for longer because of this. For me it is hard to justify this approach given that these days transcondylar screw placement has a low complication rate, has a good success rate and dogs are comfortable very soon after surgery.

Rest-assured, at The Moores Orthopaedic Clinic we will continue to collect data and work to increase our understanding of this condition. If you are an owner of a dog with HIF or a vet with such a case, then please get in touch because we would love to help you and at the same time generate the data we need to help other dogs in the future.

For more info on HIF see Andy’s Vet Clinics review here

Click here for Andy’s research publications including those on HIF

To read more blogs from cruciate disease to total hip replacement head on over to our website. 

Andy Moores

Andy Moores is one of the most qualified and experienced small animal orthopaedic surgeons in the UK. He has been a referral-only orthopaedic surgeon for over 20 years, an EBVS Specialist since 2005 and an RCVS Specialist since 2006. He has treated thousands of cats and dogs with orthopaedic problems during this time. This experience is now available to your clients and patients at The Moores Orthopaedic Clinic. If you would like to discuss a case or make a referral then you can contact Andy and the rest of the team at info@mooresortho.com. You can subscribe to our newsletter and be informed of future blogs and articles at www.mooresortho.com