We’ve all had the panicked emergency call from an owner:- ‘My Spaniel jumped off a wall/ chased a rabbit/ put its’ foot down a hole, screamed and is non weight bearing on a front leg. We take a radiograph and consider ourselves lucky if there is ‘only’ a lateral or medial humeral condyle fracture (HCF). Not often is an articular fracture considered ‘lucky’ but the challenges of the alternative intercondylar ‘Y or T’ fracture are far greater.
In both cases the principles of articular fracture management hold ie. accurate anatomic reduction, rigid fixation, early return to function and protection of soft tissues (median and ulnar nerves medially and radial nerve laterally). The HCF usually requires reduction of the condyle using a transcondylar screw and fixation of the epicondyle (plate and screws in an adult but possibly k-wire or screw alone in a pup). The Y-T fracture however is generally a 2-3 hour marathon. A medial approach to the elbow is made and the medial epicondyle reduced and stabilised with a plate and screws. Following this, assuming the medial condyle is accurately reduced, the limb is repositioned to allow management of the remaining lateral condyle component using the transcondylar screw and epicondylar plate. Any fracture comminution increases the complexity of management many fold. Outcomes of articular fractures in general and elbow fractures in particular must be guarded with significant risk of short term complications including infection, and failure of stabilisation. In the longer term ongoing lameness, infection, osteoarthritis, and recurrence of lameness associated with implant failure are all a concern.
So! Why the Spaniel and could we have predicted/prevented this?
Many dogs presenting for elbow fracture have a prior history of lameness. Spaniel breeds, particularly the Springer but all others including Cocker, Clumber and Cavalier, are heavily predisposed to what has been described as Incomplete ossification of the humeral condyles (IOHC) – A fissure partially or completely traversing the intercondylar region of the humerus. This disrupts the robust triangle of bone created by the epicondyles and the condyle and allows for excessive load transfer along one or both epicondyles resulting in fracture often associated with apparently ‘normal’ loading. In all dogs the humeral condyle has a medial and a lateral centre of ossification distal to the distal humeral growth plate. These centres fuse by 70days ± 14days and ossification is considered complete by 32 weeks. This led to an assumption that transcondylar fissures are the result of failure of fusion hence the term IOHC. However complete fissures extend beyond the ossification line traversing the distal growth plate to the supracondylar foramen. It has also been documented and is our experience that a dog that is negative for transcondylar fissure using CT can subsequently develop a fissure and associated lameness. Other theories relate to conformation, excessive activity, abnormal vasculature (this may be effect rather than cause) and also a recessive mode of heritability has been suggested with strong supporting evidence in Springers.
The reality is that IOHC or possibly more accurately humeral intercondylar fissure (HIF) remains a mystery and it is likely that the aetiology is some combination of the above and there may be more than one ‘syndrome’.
So What! The solution is simple?
– image every lame Spaniel and stabilise identified fissures?
In a referral environment it seems that every lame Spaniel must be a fracture risk, but of course the population seen is massively skewed with the multitude of other causes of lameness (ranging from nail avulsion and foreign bodies to shoulder injuries and even cervical spinal lesions often already considered and sifted out prior to referral. It is neither necessary, practical nor economic to take this approach.
However, IOHC/HIF should always be on the differential list for thoracic limb lameness in Spaniels. The condition is not uncommonly bilateral so lameness may not be evident but rather, a reluctance to descend steps/jump down. There is often pain to elbow manipulation, especially full extension and sometimes to pressure applied across the condyles. A good rule of thumb would be to suspect IOHC in any Spaniel with elbow pain, and in any Spaniel with unexplained thoracic limb lameness. If IOHC is a suspicion, strict restriction of activity (especially high risk activity that preferentially loads the thoracic limbs like descending stairs, jumping and ball chasing) should be advised. Images should be acquired. A positive radiographic diagnosis is 100% reliable. A negative radiographic diagnosis is not as fissures may be partial and even complete fissures will only be evident if imaged parallel to the beam. Computed tomography (CT) gives an accurate assessment and also allows for assessment of the other common cause of elbow pathology in the Spaniel- medial coronoid process pathology. A CT assessment of non lame Springer Spaniels presented to a referral centre for other reasons identified partial fissures in 14% of elbows, osteophytes in 60% and medial coronoid process pathology in 44%. Where a dog is investigated for lameness and both conditions coexist, the IOHC/HIF should be treated as the priority.
Treatment of the condition remains a source of some controversy and is associated with high complication rates. The current approach is to reinforce the humeral condyle using some form of implant, with standard lag and positional screws, the Fitz tubular transcondylar screw, various compression screws and the 4.5mm shaft screw all reported. The window for screw placement is small with malpositioning resulting in joint impingement, pain and osteoarthritis. Post-operative infection rates are high despite the short surgical time and limited approach, seroma is common and in the long term there remains a risk of implant fatigue leading to failure and lameness or in some case leading to fracture. Achievement of fissure union is unpredictable and at present unrelated to technique and so there is a long term dependence on the implant. A study of the 4.5mm shaft screw revealed no incidence of implant failure and the mechanical properties of the 4.5mm shaft traversing the fissure are far superior to the 4.5mm cortical screw (3.2mm shaft).
There are reported lower infection rates using lag screws vs positional screws, and medial screw placement whilst more challenging due to a narrower insertion window is also suggested to result in lower infection rates. Following screw placement and hopefully resolution of lameness, recurrence of lameness should prompt reassessment of implant integrity (often challenging due to minimal displacement and sometimes requiring surgical assessment if the index of suspicion is high) and joint fluid aspiration. Screw replacement and upsizing where possible is recommended.
In all respects these are challenging cases to manage but identification and management of dogs with humeral intercondylar fissures prior to fracture rather than as a result of fracture is eminently preferable.
This blog was written by Eandil Maddock, Adavanced Practitioner in Veterinary Orthopaedic Surgery