34th Annual Scientific Meeting proceedings

Humeral intracondylar fissure (HIF) is a partial or complete fissure present in the mid-sagittal plane of the humeral condyle with adjacent bony sclerosis.^1,2,3,4 Based on the current literature, the cause of HIF is poorly understood. Several etiologies, including a delay in ossification of the medial and the lateral aspects of the humeral condyle, incomplete ossification of the humeral condyle, and adult-onset fissure development from a stress fracture, may be causes.^1,4,5 These etiologies will affect the likelihood of achieving fusion of the fissure.

The definition of a delay in humeral ossification is when a fissure is detected after the age of 70 +/- 14 days, yet it is expected to progress and ossify without surgical intervention.^6,4 While current information is conflicting, a recent report of 12 juvenile French bulldogs (age ranging from 3-5 months) with HIF and follow-up CT, found that 11 of the 12 dogs progressed to ossification by 7 months of age without surgical intervention, suggesting that a delay in ossification is present.^3,4 Incomplete ossification of the humeral condyle of the contralateral limb was first described in detail in 1994 in dogs that presented with humeral condylar fractures.¹ Many dog breeds, including Spaniel breeds, Tibetan Mastiffs, Labradors, Rottweilers, and Yorkshire terriers have been diagnosed with IOHC.^1,2,7,8 Adult-onset HIF has been reported in 2 spaniel dogs with previous diagnostic imaging (CT or MR) documenting a normal condyle.^5,9 Both dogs presented for mild thoracic limb lameness and repeat imaging showed an intracondylar fissure. The overall prevalence of development of a fissure in previously normal adult dogs is currently not known and highlights the need for further research.

What is the evidence for healing?
Little is currently known about the healing of HIF and the ability to achieve complete resolution of a fissure is likely dependent on the underlying cause. In French bulldogs, 11 of 12 dogs progressed to achieve complete ossification over time, suggesting that surgical intervention may not be warranted. When sclerosis and fibrous tissue is present as in IOHC, it is unlikely that bone regeneration will initiate without the use of grafts. This is supported by a few case series published in dogs with transcondylar screw placement where long term radiographic follow-up showed evidence of persistent fissure along with a subset of cases with screw breakage.^10,11 Other studies reported mainly partial fissure ossification following the use of different types of transcondylar implants with bone grafting.^12,13 Considering the effect of antebrachial conformation on the presence of a fissure, a recent study investigated the use of an oblique proximal ulnar osteotomy as treatment for HIF in spaniel dogs, and reported similar results.¹⁴ It is important to recognize that many studies do not use diagnostic imaging to assess outcome in cases treated for HIF. Thus, the likelihood of achieving ossification of the fissure with the use of a transcondylar screw is still unknown.

Conclusion
Contralateral humeral intracondylar fissures are present in dogs presenting with humeral condylar fractures as well as dogs with thoracic limb lameness and transcondylar screw placement is the current surgical treatment of choice.

Current literature shows that while outcome is good in majority of surgical cases, complete healing of the fissure does not always occur following surgical intervention

It is likely that the underlying pathology varies amongst dogs and therefore, affect the likelihood of achieving complete ossification of the fissure

References

1. Marcellin-Little DJ, DeYoung DJ, Ferris KK, Berry CM. Incomplete ossification of the humeral condyle in spaniels. Vet Surg. 1994 Nov-Dec;23(6):475-87. 
2. Robin D, Marcellin-Little DJ. Incomplete ossification of the humeral condyle in two Labrador retrievers. J Small Anim Pract. 2001 May;42(5):231-4. 
3. Anderson OJ, Langley-Hobbs SJ, Parsons KJ. Humeral condylar fractures and fissures in the French bulldog. Vet Surg. 2023 Jan;52(1):134-145.
4. Hutchings VC, Rutherford S. Computed tomographic re-evaluation of skeletally immature French bulldogs previously diagnosed with humeral intracondylar fissure: 12 cases (2018-2022). J Small Anim Pract. 2024 Nov;65(11):817-821. 
5. Farrell M, Trevail T, Marshall W, Yeadon R, Carmichael S. Computed tomographic documentation of the natural progression of humeral intracondylar fissure in a cocker spaniel. Vet Surg. 2011 Dec;40(8):966-71.
6. Ticer JW: General principles, in Ticer J W (ed): Radiographic Technique in Small Animal Practice. Philadelphia, PA, Saunders, 1975, pp 97-I02.
7. Butterworth SJ, Innes JF. Incomplete humeral condylar fractures in the dog. J Small Anim Pract. 2001 Aug;42(8):394-8. 
8. Rovesti GL, Flückiger M, Margini A, Marcellin-Little DJ. Fragmented coronoid process and incomplete ossification of the humeral condyle in a rottweiler. Vet Surg. 1998 Jul-Aug;27(4):354-7. 
9. Piola V, Posch B, Radke H, Telintelo G, Herrtage ME. Magnetic resonance imaging features of canine incomplete humeral condyle ossification. Vet Radiol Ultrasound. 2012 Sep-Oct;53(5):560-5. 
10. Charles EA, Ness MG, Yeadon R. Failure mode of transcondylar screws used for treatment of incomplete ossification of the humeral condyle in 5 dogs. Vet Surg. 2009 Feb;38(2):185-91. 
11. Chase D, Sul R, Solano M, Calvo I, Joslyn S, Farrell M. Short- and long-term outcome after transcondylar screw placement to treat humeral intracondylar fissure in dogs. Vet Surg. 2019 Apr;48(3):299-308.
12. Walton MB, Crystal E, Morrison S, Onyett J, McClement J, Allan R, Straw M, Innes JF. A humeral intracondylar repair system for the management of humeral intracondylar fissure and humeral condylar fracture. J Small Anim Pract. 2020 Dec;61(12):757-765. 
13. Fitzpatrick N, Smith TJ, O'Riordan J, Yeadon R. Treatment of incomplete ossification of the humeral condyle with autogenous bone grafting techniques. Vet Surg. 2009 Feb;38(2):173-84.
14. Danielski A, Quinonero Reinaldos I, Solano MA, Fatone G. Influence of oblique proximal ulnar osteotomy on humeral intracondylar fissures in 35 spaniel breed dogs. Vet Surg. 2024 Feb;53(2):287-301.