Medial Condyle Fracture (Kilfoyle Type III) of the Distal Humerus with Transient Fishtail Deformity after Surgery

A “Fishtail deformity” is one of the well-known complications following pediatric lateral condyle or supracondylar fractures of the humerus. We herein report a case of medial condyle fracture (Kilfoyle type III) in an 11-year-old boy. He had a transient “fishtail deformity” of the trochlear groove after open reduction and internal fixation. As occurred in the current case, the bone remodeling and the improvement of ischemia of the trochlea after medial condyle fracture may be associated with the likelihood of recovery from transient “fishtail deformity.”


Introduction
Distal humerus fracture is very common in pediatric patients; however, fracture of the medial condyle of the humerus is very rare, accounting for only 1-2% of all pediatric elbow fractures [1][2][3][4]. Kilfoyle classi ed these fractures into three types according to the degree of displacement [5]. He achieved favorable results with open reduction and internal xation, even in cases involving complete and displaced fractures (type III), by diagnosing them early. Some reports suggest that the outcomes of these fractures are uniformly poor when they are diagnosed late and treated with open reduction and internal xation [1,2,6,7]. erefore, the delay in the diagnosis results in poor outcomes; however, the decision to treat via open reduction and internal xation remains controversial. e clinical course of fracture of the medial condyle of the humerus is unclear. We herein report a case of medial condyle fracture (Kilfoyle type III) with transient shtail deformity of the trochlear groove due to failure of the lateral trochlear ossi cation centers to develop after open reduction and internal xation.

Case Report
An 11-year-old boy was injured after falling to the oor and landing on his right hand. He complained of severe pain in his dominant right elbow. He came to our hospital on the same day. e initial examination showed severe swelling on the medial side of his right elbow and pain. e initial X-ray studies of the elbow showed a fracture of the medial condyle of humerus. e bone fragment was displaced laterally by the traction of the exor muscles; however, dislocation of the humeroulnar joint was not observed ( Figure 1). We diagnosed the patient with a medial condyle fracture of the humerus (Salter-Harris [8] type IV, Milch type [9] I, and Kilfoyle type [5] III). On the next day, open reduction and internal xation of the fracture were performed under general anesthesia. An incision was made over the fragment. First, the ulnar nerve was identi ed ( Figure 2). e reduced bone fragment was xed with three Kirschner wires in the accurate position. Osteosynthesis with a compression screw would have been the optimal treatment. Since multiple temporary xations with wires were needed to x the unstable bone fragment, we were afraid of bursting the fragment with a compression screw ( Figure 3).
A long arm splint was applied from the upper arm to the metacarpophalangeal joints, with the forearm kept in a neutral position for four weeks. e three Kirschner wires were removed at 8 weeks after surgery under general anesthesia ( Figure 4). Ulnar nerve palsy was not noted during the follow-up period. At 1 year after surgery, the absorption of the trochlear groove was observed on an anteroposterior view radiograph of the elbow and thus demonstrated a so-called " shtail deformity." However, the patient did not complain of elbow pain, and the range of motion was not limited. e absorption of the trochlear groove was gradually remodeled before the most recent follow-up examination (at four years after surgery). At the latest follow-up examination, a good range of motion was observed, with 0 degrees of extension and 140 degrees of exion. e patient and the patient's parents were informed that this case study would be submitted for publication and provided their informed consent.

Discussion
Medial condyle fractures of the distal humerus are a very rare type of elbow injury [1][2][3][4]. e fracture line intersects the distal humerus and the medial metaphyseal-epicondylar segment [10]. Two mechanisms of fracture have been suggested. e rst involves direct force to the apex of the exed elbow as would occur in a fall which forces the olecranon into the medial condyle of the humerus [11]. e second proposed mechanism is an avulsion-type injury, which would be caused by stress to the medial collateral ligament and exor insertions due to a fall onto the outstretched arm [1,12].
Deformity of the trochlear groove after a lateral condyle fracture in children has been referred to as a " shtail deformity." Previous studies have reported that shtail deformity was found in 40-60% of children after a lateral condyle fracture with ≥ 2 mm of displacement [13,14]. Several authors described shtail deformities and deformities of the trochlea after supracondylar and transcondylar fractures of the distal humerus [15][16][17]. e frequency of " shtail deformity" after medal condyle fracture is unknown. It was previously suggested that " shtail deformity" seldom causes functional or cosmetic problems, despite the abnormal radiographic appearance [18,19]. However, one should note that an elbow with a shtail deformity is mechanically weak and fragile, and care should be exercised to avoid damage to the trochlea at the initial treatment for a pediatric lateral condyle fracture [14].
ere are some reports of distal humerus fracture due to the fragility caused by " shtail deformity" [14,20]. Moreover,    Case Reports in Orthopedics long-term follow-up suggests that patients with shtail deformity are prone to functional impairment, ongoing pain, and the development of early osteoarthrosis [21]. e blood supply to the trochlear epiphysis is important to the clinical outcome of medial or lateral condyle fractures of the elbow. Growth center involvement is another critical feature of pediatric medial humeral condyle fractures. e distal humerus is supplied by a solitary nutrient vessel [22]. us, vascular insult has a signi cant impact on healing and subsequent humeral development. Vascular supply to the trochlear epiphysis may be diminished, leading to the suppression of growth and/or fracture union, and results in cubitus varus deformity [23,24]. Alternatively, growth may be stimulated at the injury site, yielding a cubitus valgus state. Osteonecrosis will occur if blood ow to the area ceases [24].
us, while there have been no reports on the topic, it is inferred that there are more cases of " shtail deformity" after medial condyle fractures. As occurred in the current case, the improvement of ischemia of the trochlea after medial condyle fracture may be associated with the likelihood of recovery from transient " shtail deformity"; however, the number of the patients of medial condyle fracture is too small to investigate this possibility.
In the current case, the varus deformity was not observed, and the " shtail deformity" was transient. Although the " shtail deformity" showed gradual improvement, it is unknown whether the healing process occurred due to accurate reduction and secure xation, or whether it occurred due to the anatomical speci city of the vascular supply to the medial condyle.

Conclusions
We herein described a case of medial condyle fracture of the elbow with transient shtail deformity after open reduction and internal xation. e process by which ischemia of the trochlea improves is unknown. More case reports that include detailed follow-up examinations will be needed to further elucidate the pathophysiological characteristics of medial condyle fractures of the elbow.

Conflicts of Interest
e authors declare that they have no con icts of interest. Case Reports in Orthopedics 3