Keywords elbow dysplasia - humeral intracondylar fissure - dog
Introduction
Erratum: Healing of Humeral Intracondylar Fissure Following Distal Ulnar Ostectomy
to Treat Concurrent Elbow Joint Incongruity in a Dog
The etiology of humeral intracondylar fissures (HIF) has been widely investigated
in previous studies,[1 ]
[2 ]
[3 ]
[4 ]
[5 ]
[6 ] but its etiology remains largely unclear.[1 ]
[2 ]
[4 ]
[5 ] Previous hypotheses proposed that HIF represent an incomplete fusion/ossification
of the secondary ossification centers of the humeral condyle[5 ] or can be a manifestation of a stress fissure occurring following complete ossification.[1 ]
[2 ]
[4 ]
[7 ] A genetic,[5 ] metabolic,[8 ] conformational,[2 ]
[3 ]
[9 ] and an environmental component in dogs with high levels of activity[10 ]
[11 ] have also been considered. Regardless of its etiopathogenesis, a proposed theory
attributes condylar failure to the presence of biomechanical abnormalities caused
by elbow incongruity, which produces aberrant shear forces onto the humeral condyle.[1 ]
[2 ]
[11 ]
[12 ]
[13 ] Shear forces may prevent or delay ossification or may generate a fissure/fracture
secondary to abnormal mechanical stress.[1 ]
[2 ]
[3 ]
[4 ]
[5 ] Previous literature reported significant association between elbow dysplasia and
HIF,[2 ]
[5 ]
[12 ]
[14 ] although there are no conclusive studies that directly link these two processes.
Humeral intracondylar fissures are of highest prevalence in English Springer Spaniels,
American Cocker, and French Bulldog,[1 ]
[11 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ] but this condition has also been reported in other breeds (Labrador Retriever, English
Pointer, German Shepherd Dog, Rottweiler, Tibetan Mastiff, and German Wachtel).[1 ]
[11 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ] This report aims to describe the case of a Labrador Retriever diagnosed with severe
negative radioulnar incongruity (RUI) suspected to be secondary to distal ulna retained
cartilaginous core. A computed tomography (CT) study revealed bilateral complete HIF
and bilateral medial compartment disease (MCD). Following treatment involving bilateral
distal ulnar ostectomy (DUO), follow-up CT revealed bilateral improvement of elbow
congruence and complete fusion of the left HIF ([Fig. 1 ]). To the best of the authors' knowledge, this is the first report of ossification
of an HIF after performing DUO surgery to address RUI.
Fig. 1 Two-dimensional reconstructed views of the (A –D ) left and (E –H ) right humeral condyle acquired by computed tomography showing healing of the previously
detected complete fissure of the left condyle visible in the transverse plane (A –D ) and a progression on the right intracondylar fissure after initial improvement.
Case Description
A 22-week-old entire female Labrador Retriever, weighing 16 kg and a body condition
score of 5/9, was presented for investigation of bilateral forelimb lameness persisting
for 2 months. The referring veterinarian and owners reported that the lameness began
following a short period of generalized illness, characterized by lethargy, anorexia,
reluctance, and inability to stand. Diagnostic investigations at the referring practice
included standard bilateral orthogonal radiographic views of shoulders, elbows, and
carpi, revealing no abnormalities in the shoulders or carpi but indicating retained
cartilage cores in the distal ulnas and subchondral sclerosis at the level of the
semilunar notch. On the day of the referral, the patient's lameness was subjectively
evaluated, revealing bilateral forelimb lameness, with the right forelimb being more
affected. Bilateral moderate elbow effusion was palpable, and there was severe discomfort
upon extension of the elbows.
A CT study of the antebrachia was performed under sedation using butorphanol (Torbugesic;
Zoetis US) 0.3 mg/kg and medetomidine (Domitor, Orion Pharma) 20 µg/kg, both intravenously.
The patient was positioned on the CT table in sternal recumbency with the elbows parallel
and extended cranially. Slice thickness was 1.1 mm, with 0.6-mm bed increment to ensure
high-quality reconstruction. CT image interpretation confirmed the diagnosis of bilateral
retained endochondral cartilage cores on the ulnar physis. The images also revealed
an irregular and elongated trochlear notch and a widened humeroulnar space ([Fig. 2 ]). A well-defined hypoattenuating line extending from the distal articular surface
to the supratrochlear foramen compatible with bilateral complete HIF was bilaterally
detected in the bone window reconstruction. The coronoid process appeared bilaterally
irregular and hypoattenuating, which was suggestive of medial coronoid disease and
mild secondary osteoarthritis, which prompted bilateral dynamic DUO. The surgery was
scheduled for the following day. The patient was premedicated using methadone (Comfortan;
Dechra) 0.3 mg/kg intravenous (iv) and medetomidine (Domitor; Orion Pharma) 5 µg/kg
iv and anesthesia induced using propofol (Abbott Laboratories) 1 mg/kg iv and maintained
with isoflurane (IsoFlo; Abbott Laboratories Ltd) in oxygen. Surgical intervention
involved bilateral caudolateral approaches to the distal ulnar diaphysis. The DUO
were performed using a long, narrow microsagittal saw blade, oriented based on intraoperative
and subjective assessment, approximately 2 to 3 cm proximal to the distal ulnar physis
line, allowing for the removal of approximately 10-mm sections of bone. The surgical
site was then closed: the fascia was sutured using 2–0 polydioxanone (PDS; Ethicon),
the subcutaneous tissue and skin were closed with 3–0 poliglecaprone (Monocryl; Ethicon)
utilizing an intradermal pattern, and the wound was covered with cyanoacrylate tissue
adhesive (Dermabond; Ethicon). The postoperative radiographs confirmed the accurate
positioning of the ostectomies. The patient recovered uneventfully from anesthesia.
Computed tomography studies were performed at 2, 4, and 10 months postoperatively.
On every occasion, sedation was induced as described earlier for the original CT imaging.
Assessment of the images of the left elbow revealed an improvement in congruence ([Fig. 2 ]) despite the humeroulnar space remaining markedly widened and uneven. The right
elbow initially demonstrated residual marked incongruity, featuring an increased humeroulnar
space. Subsequent to the surgical intervention, a mild improvement in congruence was
observed at the 2-month postoperative CT study. However, no further improvement in
congruence was noted in subsequent CT series ([Fig. 2 ]). The studies revealed progressive radiographic evidence of bone healing in the
left HIF, resulting in complete radiographic attenuation of the previously detected
defect as depicted in [Fig. 1 ]. On the right side, a similar decrease in size of the HIF was observed in line with
the contralateral joint. However, at the 4-month postoperative evaluation, a significant
widening of the HIF on the right was observed, prompting the decision for prophylactic
transcondylar screw placement. Additionally, a bilateral elbow arthroscopy was performed
to assess the articular cartilage, evaluate the HIF, and remove the medial coronoid
process fragment in the right elbow ([Fig. 3 ]). Four months after surgery, bilateral callus formation was observed bridging the
ulnar ostectomy, with mild irregular periosteal reaction along the caudal cortex of
the radius diaphysis. At this stage, persistent right forelimb lameness was noted,
and this further supported the decision to address the widening of the HIF and medial
coronoid process fragmentation. The patient was sedated using medetomidine (Domitor;
Orion Pharma) 5 µg/kg iv, methadone (Comfortan; Dechra) 0.3 mg/kg iv, and acepromazine
(Acetate; Novartis Animal Health) 10 mg/kg iv. Propofol (Abbott Laboratories) 1 mg/kg
iv was used to induce the anesthesia, which was maintained with isoflurane (IsoFlo;
Abbott Laboratories Ltd) in oxygen. An approach to the right medial humeral epicondylar
region facilitated transcondylar sequential drilling under fluoroscopic guidance to
permit placement of a transcondylar 5-mm, 40-mm-long titanium locking screw. Following
thorough lavage, closure was routine with intradermal suture and tissue adhesive (cyanoacrylate).
Elbow arthroscopy was subsequently conducted with a 2.7-mm-diameter 30-degree oblique
arthroscope, with the use of medial elbow portals. Joint exploration revealed a modified
Outerbridge score of 3 out of 5 on the base of the right medial coronoid process,
with a well-demarcated medial coronoid fragment that was readily detached and removed.
The affected cartilage was removed with a probe and the underlying sclerotic bone
was debrided with a hand burr until healthy bleeding subchondral bone was encountered.
Arthroscopic examination of the humeral intracondylar region revealed a line of fibrous
tissue in the humeral condyle in the location of the HIF. Absorbable cruciate sutures
(3–0 poliglecaprone; Monocryl, Ethicon) were used to close the skin incision. Arthroscopy
of the contralateral (left) elbow had a modified Outbridge score of 0, with no overt
articular portion of the partial intracondylar fissure or any medial coronoid changes
suggestive of fissuring or coronoid fragmentation. The dog recovered uneventfully
from anesthesia. The patient returned to the hospital 6 weeks postoperatively. The
owner reported a progressive improvement of forelimb function following surgery. On
presentation, the patient showed a mild bilateral lameness, as well as a mild loss
of muscle mass in the forelimbs. Elbow manipulation revealed bilateral mild pain response
to extension. Six months after transcondylar screw placement (10 months after bilateral
DUO), the patient returned for a follow-up examination and repeated CT scan. According
to the owner, the patient had experienced fluctuating mild lameness in the right forelimb,
while the overall function of the left forelimb was deemed satisfactory. On examination,
moderate muscle atrophy in the right forelimb and severe right elbow effusion were
detected. Manipulation of the right elbow was moderately painful, particularly during
extension. There was a mild reduction in the range of motion during extension of the
left elbow. Manipulation of the left carpus elicited discomfort during flexion, and
manipulation of the left elbow elicited mild pain during full extension. Mild periarticular
new bone formation was observed bilaterally, suggesting a progression of osteoarthritis.
On the left elbow, there was no evidence of HIF, although the condyle demonstrated
persistent sclerosis. Conversely, the HIF remained apparent on the right elbow, despite
the presence of a transcondylar screw ([Fig. 1 ]). The left elbow showed minimal incongruity, transitioning from a negative to a
positive radioulnar step, as indicated by the circles of best fit. The right elbow
demonstrated persistent moderate RUI ([Fig. 2 ]). At this stage, the ostectomies had fully ossified.
Fig. 2 Quantification of incongruence on the left and right elbows using a circle superimposition
technique for preoperative computed tomography (CT) images and 10 months after a distal
ulnar ostectomy (DUO) surgery.
Fig. 3 Arthroscopic image of the right elbow. A humeral intracondylar fissure HIF (red arrows ) is visible in the center of the humeral condyle. The yellow star indicates the humeral condylar trochlea articular surface. The blue star indicates the trochlear notch.
Discussion
The etiology of HIF has been a subject of interest and debate. One widely discussed
theory proposes that abnormal loading forces acting on the condyle might hinder ossification
in immature patients or lead to stress (fatigue) fissures/fractures in older patients.[1 ]
[2 ]
[3 ]
[4 ]
[5 ] Regarding the timing of union of the medial and lateral condyle ossification centers,
there is a lack of up-to-date advanced imaging-based studies. Current publications[20 ]
[21 ] estimate that ossification begins during the first 3 weeks of life, but the specific
union time varies significantly, ranging from 8 weeks to 4 months. Caution should
be exercised when diagnosing HIF in skeletally immature animals, since these estimations
are derived from old radiograph studies with inconsistent results. The term incomplete
ossification of the humeral condyle encompasses nonunion of the secondary centers
of ossification of the humeral condyle, and its etiology may involve genetic causes,
abnormal loading on the elbow joint, vascular abnormalities, hormonal variations,
or a combination of these factors.[1 ]
[2 ]
[4 ]
[5 ]
[7 ]
[8 ] The lesion's location and a potential breed predisposition in Spaniels and French
Bulldogs have led to hypotheses of problems in ossification.[1 ]
[11 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ] However, some authors have reported HIF in healthy and normally ossified elbows,
challenging the assumption of ossification issues in all cases.[4 ]
[6 ]
[22 ] On the other hand, stress fissures/fractures resulting from chronic abnormal stress
forces on healthy bone have been proposed as a contributing factor.[1 ]
[2 ]
[3 ]
[7 ]
[12 ] Evidence supporting the presence of abnormal forces on elbows with HIF comes from
a study that observed complex multidirectional patterns of screw fractures used to
treat HIF, hinting at intracondylar instability that hinders regeneration.[3 ] Histological samples from the fracture site also align with the presence of abnormal
forces, showing fibrous tissue with increased osteoclastic activity, plasma cells,
osteonecrosis, and sclerosis, with an absence of chondrocytes or cartilage matrix.[5 ]
[11 ] These findings resemble those seen in fatigue fissures/nonhealing fractures observed
in other contexts.[4 ]
[5 ]
[11 ] A suggested relationship between HIF and other elbow abnormalities has been mentioned
previously.[2 ]
[12 ] The concomitant presence of HIF with MCD and elbow incongruity has been observed,
leading to the hypothesis that incongruity may be a potential cause of condylar failure
of fusion.[2 ]
[12 ] Recent arthroscopy-based findings describing humero-anconeal incongruity in cases
of HIF and its absence in healthy elbows support the notion of a possible causal association
between these two processes.[12 ] In the case presented here, the clinical signs and examination findings localized
the source of the lameness to the elbows. The patient exhibited severe bilateral RUI
due to premature closure of the ulnar physis ([Fig. 2 ]) as well as bilateral HIF. In consideration of the patient's age and skeletal maturity,
a DUO was chosen over a proximal osteotomy.[23 ]
[24 ]
[25 ]
[26 ] The initial treatment plan included a staged approach, wherein the first step involved
DUO, followed by the subsequent placement of prophylactic transcondylar screws. Subsequent
evaluation after the ostectomies revealed partial bilateral ossification of the HIF.
Considering this observation, a conservative approach was initially taken, opting
to monitor the condition and repeat imaging tests. The left side showed a complete
union of the HIF and satisfactory improved incongruity correction ([Figs. 1 ] and [2 ]). In contrast, the right side exhibited less successful incongruity correction,
along with HIF progression and concurrent fragmentation of the medial coronoid process.
These findings prompted the decision to intervene, and a subtotal coronoid ostectomy
and placement of a transcondylar screw were performed on the right side to address
the underlying pathology.
The reasons for the variation in incongruity progression between the two sides remain
speculative. The right elbow incongruity was more severe, which could have contributed
to the suboptimal outcome. Although no complications were observed with the healing
of the ostectomies, there is a possibility that the right side ulnar ostectomy healed
prematurely, potentially explaining the less favorable outcome. It is worth noting
that cases of spontaneous ossification of HIF are exceedingly rare and have not been
widely reported in the literature. Despite multiple methods of healing enhancement,
rate of HIF healing remains lower than expected, with some authors reporting low rates
of healing[1 ] and others reporting more positive results.[14 ]
[27 ] However, there exists a single case report of a spontaneous resolution of an HIF
in a very young French Bulldog puppy.[28 ] Although this report suggests a possibility of spontaneous healing, it is crucial
to acknowledge that the tendency of these defects is typically not to heal. Furthermore,
given the age of the animal in the mentioned case, the presence of a definitive HIF
diagnosis might be questionable. While this report provides interesting insights,
it remains an isolated and exceptional observation in contrast to the established
understanding of HIF cases.
The authors speculate that improved elbow congruence after ulnar osteotomy procedures
may permit condylar healing. This suggests a possible correlation between HIF development,
healing, and abnormal forces generated by elbow incongruity. Recently, a similar healing
outcome in bilateral HIF was reported in a case report where proximal osteotomies
of the ulna were performed,[29 ] and a series of cases utilizing this treatment approach was presented at a recent
congress, providing further support to our observations.[30 ] It is important to acknowledge that this study is based on a single case report,
and further research is warranted to draw definitive judgment.
In conclusion, RUI and HIF, although seen only in this singular case, raise the intriguing
possibility of a potential relationship between the two. Such assumed association
prompts the need for further investigations into joint incongruity and HIF, and, in
particular, to assess whether DUO in juvenile patients may enhance HIF healing. Recent
investigations[12 ]
[29 ]
[30 ] support this suggested link between incongruity and HIF, reinforcing a cause-and-effect
hypothesis. Caution is advised in attributing the healing of the left-sided HIF solely
to DUO, as there may be cases of spontaneous resolution or delayed ossification in
dogs with HIF. This single case report, although yielding interesting insights, cannot
provide far-reaching recommendations on possible effects of osteotomy on cases with
HIF. Additional clinical research will be necessary to better understand the postulated
intricate effects of joint incongruity on HIF and the value of treatment by corrective
osteotomies.
