Malunion

Cubitus varus is defined as a loss of carrying angle of more than 5° compared with the contralateral elbow. It is the most common angular deformity following supracondylar humerus fractures. Historically, it has been reported in up to 58% of nonoperatively treated patients. Pirone and colleagues observed a 3% incidence after operative management of supracondylar humerus fractures. In current practice, an estimated 5% to 10% of supracondylar humerus fractures develop cubitus varus ; although rates are lower with operative treatment, varus deformity can occur, typically caused by suboptimal Kirschner wire (K-wire) placement. The typical deformity includes varus malalignment, internal malrotation, and hyperextension or recurvatum ( Fig. 1 ).

( A , B ) Clinical photographs and ( C ) anterior-posterior (AP) radiograph showing left cubitus varus malunion following supracondylar humerus fracture.

Cubitus varus has traditionally been regarded as a cosmetic concern but recent studies have shown the potential for functional complications. Two recent studies have identified cubitus varus as a risk factor for subsequent fracture. Davids and colleagues reported on 6 children who sustained lateral condyle fractures at an average of 32 months after their initial elbow fracture. These patients had cubitus varus as a sequela of their initial injury (supracondylar fracture in 5 and lateral condyle in 1), and the investigators suggest that varus deformity increases both the shear force and torsional moment generated by a fall. In a similar study, Takahara and colleagues described 9 patients with previous supracondylar fractures who sustained epiphyseal injuries (8 lateral condyle fractures and 1 physeal separation). These patients all had cubitus varus deformity following their initial fracture, and sustained the second fracture at an average of 18 months after the first.

Cubitus varus from remote fracture was also identified as a contributing factor in 18 patients with posterolateral rotatory instability (PLRI). The average varus was 15° and the tardy PLRI presented more than 20 years following the fracture. The investigators illustrate the mechanism whereby cubitus varus leads to chronic attenuation of the lateral collateral ligament complex.

Multiple studies have also identified cubitus varus as a precursor to tardy ulnar nerve palsy, despite being more commonly associated with cubitus valgus. Various mechanisms by which varus deformity leads to ulnar nerve symptoms have been described. In 14 of their 15 patients, Abe and colleagues found the ulnar nerve to be constricted by a fibrous band between the 2 heads of the flexor carpi ulnaris; 9 of these patients also had an ulnar nerve that ran anterior to the deformity. Spinner and colleagues reported on 5 patients with snapping (dislocation) of the medial portion of the triceps with the ulnar nerve, leading to either friction neuritis or compression of the ulnar nerve by the snapping triceps muscle. In contrast, Mitsunari and colleagues showed a significant association between tardy ulnar palsy and the internal rotation deformity that occurred as a sequela of supracondylar humerus fracture, rather than the varus deformity. They proposed that the internal rotation involves posterior displacement of the distal medial fragment, which causes stretching of the ulnar nerve with elbow flexion.

Various osteotomies have been advocated, all of which attempt to correct varus angulation; complex and dome osteotomies may also improve rotation or hyperextension, or minimize lateral prominence. Proponents of complex osteotomies cite better correction and cosmesis, whereas advocates for simple closing wedge osteotomies cite functional improvement and lower complication rates.

In most cases, a simple closing wedge osteotomy fixed with percutaneously placed K-wires suffices. In a systematic review of 40 studies involving nearly 900 patients, Sofelt and colleagues found a mean angular correction of 27.6° across all osteotomy types. No technique showed statistically significant superiority to another, and there were no differences in complication rates. The overall complication rate was 14.5%, with transient nerve palsy being the most common. In a recent retrospective study of 90 patients treated with a French osteotomy (a lateral closing wedge osteotomy that relies on an intact medial hinge and lateral screw and wire tension-band construct), North and colleagues reported a complication rate of 3.3% and no nerve injuries.

The timing of corrective osteotomy is controversial. At a minimum, surgery should be delayed until the fracture has healed, remodeling is mature, and range of motion has reached maximum improvement. Ippolito and colleagues recommended waiting until close to skeletal maturity because several of their patients showed loss of correction with continued growth. However, Voss and colleagues found that 11% of the patients in their series showed disruption of medial-sided growth. They thought that this could lead to progressive worsening of deformity and recommended corrective osteotomy at least 1 year after injury, but not necessarily waiting until skeletal maturity.

Nonunion and Malunion

Nonunion is more common in lateral condyle fractures than supracondylar humerus fractures ( Fig. 2 ). The reason for this is likely multifactorial and may involve the intra-articular nature of the fracture, poor blood supply of the epiphyseal fragment, and the pull of the common forearm extensor tendon. Risk factors for nonunion include delayed diagnosis and nonoperative treatment. Symptomatic patients may complain of ulnar nerve dysfunction, pain, instability, or deformity. Treatment depends on the timing of diagnosis and the distinction between delayed union and nonunion. Most investigators agree that acute fractures (<3 weeks from injury) with more than 2 mm of displacement should be reduced and stabilized surgically. In addition, there is agreement that symptomatic nonunions (>12 weeks from injury) also benefit from surgery.

Lateral condyle nonunion in a 5-year-old boy. ( A ) At 7 weeks postinjury, the lateral condyle shows evidence of nonunion on this AP radiograph. ( B ) AP and ( C ) lateral radiographs following open reduction and internal fixation.

Delayed presentation (3–12 weeks from injury) of a displaced fracture continues to be a controversial problem. Cited reasons for nonoperative treatment include the possibility of asymptomatic malunion with immobilization alone, difficulty with reduction given soft tissue swelling and callus formation, tenuous blood supply to the distal fragment, and the risk of physeal arrest. Although older studies found no benefit with surgery in patients treated greater than 3 to 6 weeks after injury, newer studies advocate open reduction and fixation. Wattenberger and colleagues reported on 9 patients who underwent open reduction and pin fixation greater than 3 weeks postinjury. Union was universal and there was no avascular necrosis. Similarly, Agarwal and colleagues treated 22 patients greater than 4 weeks from injury with open reduction and pinning or screw fixation in older children. They reported overall favorable results, with 2 cases each of nonunion and physeal arrest, and 1 case of avascular necrosis. Both studies emphasized the importance of maintaining the posterior soft tissue attachments in order to avoid avascular necrosis.

Treatment of an established nonunion should be guided by the severity of symptoms, patient age, and functional goals, as well as the patient’s and family’s expectations and commitment to participate in therapy. Risks of surgery include osteonecrosis, loss of range of motion, physeal arrest, and persistent nonunion. Long-standing nonunions from fractures extending lateral to the capitellotrochlear groove (Milch type I) are more likely to be symptomatic, and may benefit from surgical correction more than fractures with an intact radiocapitellar joint.

Given the complexity of lateral condyle nonunion, multiple surgical strategies have been suggested. Papandrea and Waters describe the surgeon’s dilemma as choosing between fixation in situ with the potential for angular deformity, or reduction with the potential for avascular necrosis. Either choice may also require a supracondylar osteotomy, bone grafting, and nerve decompression/transposition, which can be performed at the time of fracture fixation or in a staged fashion.

High union rates with good functional outcomes have been reported with fibrous take-down, reduction, and fixation with K-wires, as long as soft tissue stripping is minimized. These investigators recommend ranging the joint after provisional anatomic fixation; if range of motion is decreased compared with baseline, the fragment is replaced in its displaced location and stabilized. They also recommend fixation adjuncts, as needed, including cancellous screws for large fragments, a tension-band technique, or a narrow plate. If the pull of the common extensor tendon makes reduction difficult, a lengthening of the common extensor aponeurosis can be performed.

An alternative is in situ stabilization with supracondylar osteotomy to treat the resulting valgus angulation. Knight and colleagues showed good results with fragment compression alone using a percutaneously placed cancellous screw, as long as the interval between injury and nonunion diagnosis was less than 16 weeks.

The timing of corrective osteotomy is subject to the same considerations cited earlier for varus deformity. Correction is generally delayed until the child has neared skeletal maturity and most investigators recommend waiting at least 1 year from initial injury before pursuing late angular correction.

In the rare case of lateral condyle malunion, an intra-articular osteotomy can improve elbow range of motion by more than 35°; there was a trend toward better results in Milch type I fractures. For all treatment strategies of nonunions and malunions, the authors emphasize the importance of maintaining the posterior soft tissue attachments to the lateral fragment in order to avoid osteonecrosis.

Lateral spurring or overgrowth following lateral condyle fracture is common. In a study of 212 fractures, spurring was seen in 73%, and the size of the spur correlated with the degree of displacement. Range of motion was not significantly affected in this series. Although potentially a cosmetic concern, the lateral spur seems to be of no functional importance.

Nonunion

Medial epicondyle nonunion or fibrous union is reported in most displaced fractures treated nonoperatively ; however, only 21% of all nonunions are symptomatic. Symptoms may include pain, weakness, decreased range of motion, and ulnar nerve compression. Treatment should be tailored accordingly. Fragment excision and fixation have both been advocated. Smith and colleagues reported union in 7 out of 8 patients and return to athletics in all patients treated with open reduction and screw fixation. In 5 patients with valgus instability at an average of 10 years from injury, Gilchrist and McKee performed fragment excision and advancement of the ulnar collateral ligament; all patients had good patient-reported outcome scores. In contrast, Farsetti and colleagues reported poor results from fragment excision at 34 years of follow-up. Complications included pain, weakness, paresthesias, and instability. In an effort to decrease hardware-related complications, Shukla and Cohen performed open reduction and internal fixation (ORIF) using a tension-band technique for symptomatic nonunions in 5 patients. They achieved union in all patients and reported high satisfaction and no complaints related to elbow stiffness or prominent hardware.