Abstract
Closed reduction and percutaneous pinning is preferred method of treatment for displaced supracondylar fractures in children. A crossed pin configuration is considered to be biomechanically more stable than lateral pins alone, however, ulnar nerve can be injured by medial entry pin. We conducted a prospective study of 19 cases of Gartland Type 3 supracondylar fracture humerus in children which were fixed by K wires using a novel technique of pin passage. This technique involves passage of two parallel lateral smooth Kirschner wires and another antegrade lateral K wire passed from the lateral supracondylar ridge proximal to the fracture site crossing the previous two pins taking purchase in the subchondral bone of the medial condyle. A good alignment was achieved by closed reduction under image intensifier in 15 cases while open reduction was required in 4 cases. There was no incidence of loss of reduction in the post operative period. K wires were removed after 3 to 5 weeks postoperatively and mobilisation was started. All the patients regained full range of motion at 6 to 8 weeks following surgery. There were no nerve palsies, cubitus varus or hyperextension deformity in our patients. This pin construct represents a good option in the treatment of Gartland type 3 supracondylar fractures in children.

Introduction
Gartland type 3 supracondylar humerus fracture is conventionally treated by closed reduction and percutaneous cross K wire fixation or if required open reduction with the same modality of fixation. Different pin passage constructs have been used which offer different grades of stability.

Medial pin passage percutaneously puts the ulnar nerve to risk of injury. Various studies put down the risk of ulnar neuropraxia from 3% to 5%.1-3 To avoid this iatrogenic ulnar nerve palsy, lateral pin constructs have been used but at the cost of compromising fracture stability.

Our technique involves passages of two Kirschner wires from the lateral condyle and a 3rd K wire from the lateral supracondylar pillar proximal to the fracture site crossing the previous two pins taking purchase in the subchondral bone of the medial condyle. This construct represents a good option in the treatment of grade 3 supracondylar fractures in children providing the biomechanical advantages of cross wiring and eliminating the risk of iatrogenic ulnar nerve palsy.

Material and Methods
We have conducted a prospective study of 19 cases of Gartland type 3 supracondylar humerus fractures of extension type. As per Gartland's classification, types 1 and 2 fractures were excluded from the study. Good reduction was achieved with closed reduction in 16 cases while open reduction was required in 3 cases. For all open reductions the lateral approach was used, followed by our pin construct.

Table 1 : Patient demographics Age Number of cases Male Female 3-5 7 5 2 6-9 6 4 2 10 and above 6 4 2 Total 19 13 6

The fracture was encountered more on the left side (12) than the right side.⁷ Average age was 7.1 years.
On an average surgery was undertaken within 25.7 hours of injury.
The timing of K wire removal was 3 weeks post operatively in closed pinning and 5 weeks following open reduction.

Technique
Closed reduction and percutaneous pinning

All the patients were operated under general anaesthesia with the patient placed in supine position by the edge of the table. Fracture reduction was achieved by closed manipulation. Reduction was confirmed on the image intensifier in anteroposterior and lateral planes. Care was taken to ensure that the image intensifier is rotated and not the patient's limb to avoid any slippage of reduction.

Two 1.6 mm smooth Kirschner wires are passed superiorly from the lateral condyle at an angle of 30 degrees to the humeral axis across the fracture site to obtain purchase in the medial cortex. A 3rd K wire was passed from the lateral supracondylar pillar proximal to the fracture site in a downward direction to gain purchase in the subchondral bone of the medial condyle under image intensifier. Care was taken not to breach the subchondral bone so as to avoid ulnar nerve injury. Reduction and position of the wires was once again confirmed and stability was checked by rotation in real time in imaging.

Open reduction

Fig.1 : Pre-operative AP X-ray of type 3 supracondylar fracture

In 4 cases open reduction was required in view of inability to achieve acceptable reduction. Open reduction by the lateral approach was employed by the same pin construct. We favour lateral approach over posterior as it involves approach through intermuscular planes and avoids postoperative stiffness. Additionally, the lateral approach can be done in the supine position and there is no need to shift to lateral position in case closed reduction is not possible.

Postoperative care
Wires were bent, cut and kept proud to facilitate removal of K wires.

Above elbow plaster splint was applied for a period of 3 weeks, at the end of which active assisted mobilisation was started.

Patients were examined on 5th day, 3 weeks, 6 weeks and 3 months for assessment of nerve injury, stiffness, deformity, elbow range of motion. Wires were removed on the appearance of callus, which was 3 weeks for closed pinning and approximately 5 weeks for open pinning.

Table 3 : Results   Loss of elbow ROM (degrees) Loss of carrying angle (degrees) Excellent 0-5 0-5 Good 6-10 6-10 Fair 11-15 11-15 Poor More than 15 More than 15

Results
Patients were assessed on the basis of Flynn's criteria.⁴ Flynn's criteria is stringent in grading the result since it takes into consideration both the factors of loss of carrying angle and loss of range.

By this grading system, 16 cases had excellent results while 3 patients had good results. None of the cases had fair or poor outcome.

Patients were followed for a mean of 11 week None of the patients had any post-operative nerve palsy, pin tract infection or loss of reduction, cubitus varus or hyperextension deformity.

Fig. 2: Pre-operative lateral X-ray of type 3 supracondylar fracture	Fig. 3: Post-oprative AP X-ray.

Discussion
Closed fracture reduction and percutaneous K wire fixation is an accepted modality of treatment for displaced supracondylar fractures in children.

Various treatment modalities have been described for the treatment of this fracture. E. Ippolito et al and Williams et al are among the few researchers advocating only closed reduction and plaster application.⁵ On the other hand, Kurer et al have advocated open reduction internal fixation to achieve good results.⁶ However, most of the studies strongly favour closed reduction and percutaneous pinning as the most successful modality of treatment. Excellent work by Joseph Flynn et al, Barbara Minkowitz et al and others have conclusively proved that closed percutaneous pinning is the best treatment option for type 3 supracondylar fracture.^7-13 But the issue of optimal pin construct remains control controversial.^14-15

Fig. 4: Post-oprative lateral X-ray.

In closed pinning, various pin constructs have been employed to fix this fracture-medio-lateral crossed pin construct, two lateral divergent wires, lateral parallel wires, lateral convergent wires, three lateral wires. Zionts et al¹⁶ and Lee et al¹⁷ have assessed the strengths of the above pin constructs by applying rotational force to recreated fractures in cadaveric bones. They have found the medio-lateral crossed pin construct to be the strongest followed by lateral divergent pins and lateral parallel pins. The lateral convergent construct was found to be the weakest. Although these studies provide an insight into inherent stability of certain pin configuration, application of three findings to clinical setting is limited since studies were done on sawbones and or cadaveric species without soft tissue attachment.

Additionally, most of the studies suggest that the mediolateral cross pin construct is biomechanically quite rigid, but carries the risk of ulnar nerve injury (2-5%) during the passage of the medial K wire^2,3 since the ulnar nerve is very difficult to palpate around the medial epicondyle due to the presence of oedema. Also during the flexion reduction manoeuvre the ulnar nerve is pushed close to the medial epicondyle risking it to injury. Royce et al reported neurological complications in 4 of 143 children (2.7%) after Kirschner wire fixation of supracondylar fractures.³ Late ulnar neurapraxia occurred in 2 patients and in the other 2 patients nerve injuries (one ulnar and one radial) were caused during insertion of the Kirschner wires. Lyons et al described ulnar nerve palsies after closed or open reduction and percutaneous pinning for supracondylar fractures in 17 patients who had normal neurologic examinations preoperatively. Only 4 had the medial pins removed and 2 others required explorations, which showed no interruption of the nerve. Although all patients had complete return of function eventually, some did not have complete return of function even after 4 months.
The lateral pinning techniques although, avoids injury to the ulnar nerve but carries the disadvantage of inadequate stabilisation with risk of postoperative loss of fixation.¹³

Our technique involved passage of two smooth lateral K wires followed by an antegrade pin from the lateral supracondylar ridge crossing the fracture site to gain purchase in the medial condyle subchondral bone without breaching it. We advocate using two lateral wires instead of one as the additional wire adds to the stability of the construct without any complications. Since the medial condyle is not breached there is absolutely no risk of ulnar nerve injury as observed in our series. The absence of any post-operative loss of reduction and cubitus varus, hyperextension in our series confirms the stability of this pin construct.

Although our study lacks the support of relevant biomechanical data but the cross wire configuration achieved by inserting wires from the lateral aspect is similar to that obtained via the conventional medial and lateral technique.

When we embarked on this technique there were concerns raised about the risk of radial nerve injury during insertion of the proximal K wire, but at the point of entry of the antegrade wire on the lateral ridge the radial nerve is situated anterior to the lateral intermuscular septum and injury to it can be avoided by entering the skin slightly posterior to the midcoronal plane. This is substantiated by the fact that there was no incidence of radial nerve palsy in our study.

Conclusion
Our technique of fixation offers the following advantages

1. It is a safe technique with no risk of injury to radial or ulnar nerves.
2. Provides stable fixation
3. Technically not very difficult to execute
4. Achieves reproducible good results

Considering the above advantage we recommend this technique as a sound option for the treatment of grade 3 supracondylar fractures in children.

References

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