Keywords
spontaneous regression - French bulldog - humeral intracondylar fissure
Introduction
Humeral intracondylar fissure (HIF) is a widely reported condition associated with
variable degrees of morbidity.[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8] Presentation ranges from clinically silent, to variable thoracic limb lameness,
or as a precursor to condylar fractures with or without prodromal lameness. The aetiology
remains controversial and may vary between breed or individuals. Normal anlage ossification
of the canine humeral condyles originates from discrete ossification centres, radiographically
evident at 14 ± 8 days after birth. As ossification progresses these centres remain
separated by a cartilaginous plate until ossification occurs at 70 ± 14 days after
birth.[1]
[9] Thereafter, only the distal humeral physeal plate is present with subsequent closure
reported between 5 and 8 months of age.[10]
[11]
There are several proposed aetiopathologies for HIF development including failure
of routine humeral epiphyseal ossification[1]; stress fracture propagation[2]
[3]
[4]
[5]; secondary to dysplastic elbow joints presenting as either humeroanconeal impingement[12] or radioulnar incongruency[2]
[13]; or as a heritable defect[1]. De novo HIF formation has also been reported in two Spaniel dogs with previously
documented unaffected condyles.[14]
[15] While HIF in dogs is typically seen in skeletally mature individuals, it has been
documented in patients as young as 4 months of age.[3]
[5]
In addition to the classically recognized Spaniel signalment, French bulldogs have
been reported as an at-risk breed for HIF and associated humeral condylar fractures.[16]
[17]
[18] The prevalence of HIF has recently been reported in two discrete populations of
French bulldogs. While absent in non-lame populations presenting for non-orthopaedic
conditions, a high prevalence of contralateral HIF was noted where French bulldogs
present with documented humeral condylar fractures.[16]
[19]
[20] To the best of the authors' knowledge, there are no reports of spontaneous resolution
of HIF lesions in French bulldogs within the literature.
Case Description
A 4-month-old (115 days) old male entire French bulldog weighing 7 kg was presented
because of an acute onset left thoracic limb lameness after normal exercise 48 hours
previously. Previous lameness had not been noted by the owner. Orthopaedic examination
revealed diffuse periarticular soft tissue swelling, pain and crepitus of the left
elbow with intact neurological function and no visible skin wounds. No additional
trauma or comorbidities were recognized during the remainder of the routine physical
or orthopaedic examination.
Under general anaesthesia, computed tomography (CT) imaging of the elbows was performed
using a 32-slice helical scanner (SOMATOM go.Now, Siemens Healthcare Ltd, Park View,
Watchmoor Park, Camberley, Surrey, UK). Key radiological findings included a non-displaced
Salter Harris IV fracture of the left medial humeral condyle and a HIF affecting the
right condyle. This was characterized by a faint, ill-defined hypoattenuating line
with sclerotic margins bisecting the humeral condyle from the articular surface to
the supratrochlear fossa ([Fig. 1]).
Fig. 1 Day 0 right humeral condyle (W/L 500:2500) viewed in serial transverse images through
the humeral condyle showing hypoattenuating intracondylar line bordered by hyperattenuating
sclerotic bone.
Left humeral medial condylar fracture osteosynthesis was performed by open reduction
and internal fixation with a combination of a transcondylar screw and caudomedial
locking plate in neutralisation mode. Postoperative orthogonal radiographs demonstrated
anatomic fracture reduction and appropriate implant positioning, and the patient was
discharged the following day. Postoperative care instructions comprised strict cage
rest, with short leash walks three to four times daily for several minutes. Once daily
oral meloxicam (Loxicom 1.5 mg/mL oral suspension, Norbrook Laboratories Ltd) for
14 days was prescribed. Serial orthopaedic and CT examinations were performed to assess
both fracture healing and the right elbow HIF at 36 and 105 days postoperatively.
Computed tomographic examination at 36 days revealed union of the left humeral condyle
fracture characterized by an absence of visible intracondylar lucency immediately
cranial and caudal to the transcondylar screw with complete uniform cortical margins
of subchondral bone, supratrochlear foramen and the medial epicondylar crest in agreement
with the visible findings on orthogonal radiographs. The previously described HIF
was still visible but less evident than in the initial images; the hypoattenuating
line was narrower, and bordered on each side with a narrow sclerotic zone ([Fig. 2]). Following documented fracture healing all medications were withdrawn and a staged
increase in activity was recommended by gradually increasing the duration of lead-controlled
walks. At final CT examination of the right elbow joint (105 days postoperatively),
the previously noted hypoattenuating line was no longer present, and there was no
irregularity in the subchondral bone contour. A small, ill-defined area of sclerosis
was still visible within the humeral intracondylar region ([Fig. 3]). Resumption of normal unrestricted activity was allowed again, based on these findings.
Right thoracic limb lameness was not seen at follow-up orthopaedic re-examination
(105 days postoperatively) or reported by the owners at telephone follow-up 389 days
following original HIF diagnosis.
Fig. 2 Day 36 right humeral condyle (W/L 500:2500) viewed in serial transverse images through
the humeral condyle showing a faint hypoattenuating intracondylar line bordered by
hyperattenuating sclerotic bone.
Fig. 3 Day 105 right humeral condyle (W/L 500:2500) viewed in serial transverse images through
the humeral condyle showing a faint hypoattenuating ovoid intracondylar region bordered
by mildly hyperattenuating sclerotic bone. A discrete hypoattenuating line is not
present.
Discussion
Spontaneous resolution of HIF has not, to our knowledge, been previously documented.
As stated, the aetiopathogenesis of HIF remains elusive with various hypotheses proposed
and broadly considered as failure of normal ‘anlage’ ossification or fracture propagation
secondary to an underlying pathology.[1]
[2]
[3]
[4]
[5]
[12]
[13]
[19]
[20]
[21]
[22]
[23] Indeed, the possibility that a different process causes these fissures in different
breeds or individuals at different ages cannot be excluded.
In this skeletally immature dog, it would seem plausible that resolution of an abnormality
of ossification could have permitted spontaneous healing of the fissure. Ossification
is a complex physiological process, regulated by both intrinsic and extrinsic mechanisms.
The effect of external forces on the natural epiphyseal ossification process is important
and has been demonstrated experimentally.[24] Forces applied parallel to the direction of axial loading promote early ossification,[25]
[26] while perpendicular or shear forces may cause radiographic physeal widening but
not a delayed closure.[27] In this present case, it is also possible that strict cage rest, as part of the
recommended postoperative management for contralateral humeral condylar fracture repair,
leads to a period of reduced forces acting on the condyles providing a biomechanical
environment to allow the fissure to ossify. Alternatively, a potential spontaneous
resolution of a transient elbow incongruity may have occurred during this time period.
The latter possibility has been suggested to play a role in the development of medial
coronoid process disease, and, as in that condition might be expected to vary in its
effect between individuals.[28]
[29] However, elbow joint incongruity was not detected on initial CT examination to support
this theory.
In the case presented here we could argue_an alternative hypothesis that this was
not resolution of a HIF but rather delayed ‘normal’ ossification of the humeral condyle
in an individual compared with what is typically described (70 ± 14 [standard deviation]
days). The frequently referred to timeframe of 70 ± 14 days after birth was derived
from a combination of dog breeds including German Shepherd, Beagle, Collie and bulldogs
in a single study.[9] In the latter breed, Hare's (1961) study noted ossification centres were found to
develop comparatively later.[19] Such breed-specific delayed ossification could result in mechanically compromised
condylar structures in French bulldogs at a time in life when intensity of exercise
typically increases. The median age of 5 months at which French bulldogs present with
humeral condylar fractures reported by Sanchez Villamil and colleagues,17 and the 56% incidence of contralateral HIF in French bulldogs aged more than 13 weeks
with condylar fractures reported by Strohmeier and Harris16 could also be supported by this proposed delayed ossification.
Further investigation would be needed to differentiate between these hypotheses; however,
the implication of these findings suggests that there is a possibility for spontaneous
HIF resolution or delayed ossification which should be considered when approaching
clinical cases. Where incidental HIF is detected in skeletally immature patients,
it may be prudent to re-take radiographs of the condyles to assess the status of the
HIF at subsequent points of time prior to prophylactic surgical stabilization. By
extension, such a staged approach could arguably be preferable to concurrent treatment
of a fracture and contralateral HIF. Clearly the benefit of potentially avoiding an
unnecessary surgery for any incidentally diagnosed HIF in a young French bulldog must
be balanced against the risk of fracture. It has been shown that a minority (24%)
of incidentally-diagnosed HIFs in a single cohort of adult Spaniels required surgical
intervention, and fractures can occur without prodromal lameness.[5] Unfortunately, as is the nature of single case reports, we lack the data to make
an informed decision where the balance of risk lies in such cases. If an initial conservative
approach is adopted, it would seem prudent to minimize the risk of fracture by strict
exercise moderation and specific attention to lameness monitoring with serial imaging.
In conclusion, we report the presence of HIF in a skeletally immature French bulldog
at an age beyond the reported time for closure, which was noted to spontaneously resolved
at follow-up cross-sectional imaging.
