A comparative study of two percutaneous pinning techniques (lateral vs medial–lateral) for Gartland type III pediatric supracondylar fracture of the humerus
© The Author(s) 2016
Received: 28 August 2015
Accepted: 29 April 2016
Published: 16 June 2016
The management of displaced supracondylar fracture of the humerus with closed reduction and percutaneous pin fixation is the most widely accepted method of treatment, but controversy continues regarding the pin fixation techniques. A prospective randomized controlled study was undertaken to compare the stability, functional outcome and iatrogenic ulnar nerve injury between lateral pin fixation and medial–lateral pin fixation.
Material and method
Sixty-two patients with Gartland type III supracondylar fracture of the humerus were randomized into two groups—lateral pin fixation (n = 31) and medial–lateral pin fixation (n = 31). Primary assessment was performed for major loss of reduction and iatrogenic ulnar nerve injury. Secondary assessment included clinical outcome, elbow range of motion, radiographic measurements, Flynn grade, and complications.
There were two (6.5 %) iatrogenic ulnar nerve injury cases in the medial–lateral entry group and two (6.5 %) cases with mild loss of reduction in the lateral entry group. No major loss of reduction was observed in either of the groups. There was no statistically significant difference in change of Baumann angle, metaphyseal–diaphyseal angle, Flynn grade, carrying angle, and the total elbow range of motion (P < 0.05) between the two groups.
Lateral pin fixation offers similar functional and radiological outcome and almost equal mechanical stability compared with medial–lateral pinning without the risk of iatrogenic ulnar nerve injury.
Level of evidence [OCEBM 2011]
Supracondylar humerus fractures constitute 60–65 % of all the fractures around the elbow joint, with a peak incidence between 4 and 7 years of age in children . The main complications associated with supracondylar fractures are malunion, ischemic contracture and neurovascular damage [2, 3]. Of the methods described for the treatment of displaced extension-type supracondylar humeral fractures, closed reduction with percutaneous pin stabilization is the current preferred method of treatment . However, controversy persists between lateral or crossed medial and lateral pin fixation techniques .
Two major complications associated with percutaneous pinning are iatrogenic ulnar nerve palsy and loss of reduction, resulting in cubitus varus deformity [5, 6]. The optimal pin configuration that provides adequate stability of the fracture and minimizes the risk of iatrogenic neurovascular injury is still a matter of discussion.
The advantage of medial−lateral entry pin fixation is probably increased biomechanical stability, although iatrogenic ulnar nerve injury may result from placement of the medial pin [2, 4, 7]. Conversely, the advantage of lateral entry pin fixation is avoidance of iatrogenic ulnar nerve injury, although the construct may be less stable biomechanically [2, 8–10]. A few studies reported that there is no significant advantage of cross pins in comparison to lateral pins [11, 12].
The aim of this study was to compare the efficacy in terms of stability, functional outcome and iatrogenic ulnar nerve injury between lateral entry pin fixation and medial–lateral entry pin fixation of completely displaced (type-III) extension supracondylar fractures of the humerus in children. The null hypothesis was that there would be no difference between the pin fixation techniques in terms of major loss of reduction or iatrogenic ulnar nerve injury.
Materials and methods
We conducted a prospective, single-blinded randomized control trial in the Department of Orthopaedics, Gauhati Medical College and Hospital, Guwahati, Assam, India for a period of one year, after obtaining ethical committee approval. Full written informed consent was taken from parents/legal guardian before participating in this study. Inclusion criteria for this study were aged between 3 and 12 years, closed Gartland type III supracondylar humeral fracture , duration of injury <4 days, and competent neurological and vascular status of the affected limb. Exclusion criteria were duration of injury >4 days, inability to take part in postoperative rehabilitation, open fractures, medical contraindications to surgery, fracture requiring open reduction or neurovascular exploration, previous ipsilateral elbow fracture, and floating elbow injury.
A total of 216 patients with supracondylar humerus fractures were admitted to the orthopedic wards either through the outpatient department or emergency services. Of the 216 patients, 140 were excluded from the present study as they did not fulfill the inclusion criteria. These included compound fractures (10 cases), aged >12 years (12 cases), were not fit for surgery/refused surgery (15 cases), were associated with ipsilateral forearm fractures (6 cases), or were being treated conservatively for Gartland I and II fractures (46 cases). The remaining 76 patients were enrolled in the study. The method of patient selection for lateral entry or medial−lateral entry was random, using a computer-generated randomization table from http://www.randomization.com. The seed for the random number generator was obtained from the clock of the local computer and was printed at the bottom of the randomization plan. Fourteen patients were excluded from the final analysis because of lost to follow-up. Our analysis included 62 patients who were followed up for at least 6 months at 1, 3, 6, 14, 18, and 24 weeks and then at 3-month intervals.
All the children with suspected supracondylar fractures of the elbow were assessed for vascular and neurological status. Anteroposterior and lateral radiographs were performed. All displaced supracondylar fractures were admitted and the injured elbow was immobilized in an above-elbow splint with the elbow at 30°–45° of flexion and limb elevation. Pulseless viable limbs [absent radial pulse because of complete transaction, intimal tear or compression (temporary compression or reversible spasm) of brachial artery, but hand viable because of good collaterals around elbow] were also included in the study. In all such cases a vascular surgeon was present for the surgery but radial pulsation appeared in all cases after close reduction and pinning. Therefore, brachial artery exploration was not needed for any of our cases.
A single preoperative parenteral dose of cefuroxime was given at the time of induction and postoperatively, and oral cefuroxmime was given for three days at the time of discharge. Postoperatively, the extremity was placed in a well-padded posterior splint with the elbow flexed to 90°. Any patients with immediate postoperative ulnar nerve deficit were investigated and the pin was placed in another location. For all patients, immediate postoperative radiographs were taken to determine the maintenance of the reduction. The operated limb was elevated and carefully observed at regular intervals for any neurovascular deficit.
During follow-up in the outpatient department, clinical-radiological evaluation was performed for maintenance of reduction (at first follow-up) and functional outcome, which included passive range of motion, measurement of carrying angle, Baumann angle, metaphyseal–diaphyseal (MD) angle, neurovascular status, superficial and deep infection, and the necessity to re-operate. Clinical evaluation was graded according to carrying angle and elbow range of motion using the criteria of Flynn et al. . Radiographic evaluation was performed by anteroposterior and true lateral view at 1, 3, and 6 weeks and at 3 and 6 months. In the third week, the pins were removed without anesthesia. At 3- and 6-month follow-up, the children were evaluated for full function, minor limitation of function and major loss of function.
The final results were graded as excellent, good, fair and poor, according to the loss of range of motion and loss of carrying angle using the criteria of Flynn et al. Loss of reduction was graded by the loss of Baumann angle using the classification of Gordon et al. . Statistical screening of treatment effects was measured by relative risk reduction, absolute risk reduction with adjustment for a small sample size and confounders in the study. The Fisher exact test and unpaired t test were applied to check for the presence of a significant difference in outcome variable between the two groups. The software InStat version 3.10, 32 bits from GraphPad was used in the statistical analysis. A P value of <0.005 % was considered significant.
Analysis of carrying angle loss, Baumann angle loss, MD angle loss and range of motion loss at 6-month follow-up
Lateral entry group (mean ± SD)
Medial–lateral entry group (mean ± SD)
Loss of carrying anglea
4.12 ± 2.10
3.80 ± 2.02
Loss of Baumann anglea
4.74 ± 1.29
4.99 ± 0.87
Loss of MD anglea
2.34 ± 0.65
2.21 ± 0.61
Loss of range of motiona
8.03 ± 3.65
7.54 ± 1.89
Comparison of variables
Lateral entry (n = 31)
(n = 31)
Mean age of the patient (years)b
8.25 ± 2.26
8.55 ± 2.33
26 (83 %)
22 (71 %)
5 (17 %)
9 (29 %)
Hospital stay (days)b
2.32 ± 0.50
2.51 ± 0.64
25 (87 %)
23 (74 %)
6 (13 %)
8 (26 %)
Average delay from injury to surgery (days)b
2.25 ± 0.68
2.35 ± 0.66
Average follow-up (weeks)b
35.29 ± 9.84
33.529 ± 10.36
Pin tract infectiona
3 (9.6 %)
1 (3.2 %)
Iatrogenic ulnar nerve injurya
0 (0 %)
2 (6.5 %)
Functional results (Flynn grading)a
23 (74.19 %)
26 (83.87 %)
8 (25.82 %)
5 (16.12 %)
The ideal treatment for completely displaced (type-III) extension supracondylar fractures of the humerus in children is closed reduction and percutaneous pin fixation. However, controversy regarding the optimal technique, whether lateral or crossed medial–lateral pin fixation is still debatable.
According to earlier studies, the advantage of medial–lateral entry pin fixation is increased biomechanical stability [7, 15], although iatrogenic ulnar nerve injury may result from placement of the medial pin . Conversely, the advantage of lateral entry pin fixation is avoidance of iatrogenic ulnar nerve injury, although the construct may be less stable biomechanically [10, 11, 16, 17] and failure to provide torsional stability, for which some have suggested adding a third medial pin [11, 18]. A biomechanical study by Zionts et al.  demonstrated that crossed pinning is more stable than lateral pinning in rotational testing as well as varus and valgus loading. However, a study by Skaggs et al.  demonstrated no clinical difference in stability between crossed and lateral pins.
The average loss of the carrying angle, Baumann angle, M–D angle and range of motion in the lateral pinning cases in our study may be related to a comparatively less stable construct with two lateral pins compared to crossed medial–lateral pins. According to the classification by Gordon et al. , the mild loss of reduction in two cases of lateral entry group in our study suggest that lateral entry is biomechanically weaker. Although radiological and clinical union occurred in a similar time period without any residual deformity, the loss of both the range of motion and the carrying angle was greater in these two patients, compared to those without loss of reduction. In a recent analysis of the two techniques by Lee et al. , the loss of reduction in the lateral entry group was 0–11.8 %. An older study by Kallio et al. found a reduction of 14 % , a study by Davis et al. found 29 % , while a study by Skaggs et al. found 0 % . The risk of loss of reduction after lateral entry pin fixation can be minimized by following proper pin placement technique, with divergent pins, pins that engage the lateral and central columns, and the use of a third lateral pin if needed.
The reported risk of iatrogenic ulnar nerve injury from medial entry pin fixation has been found to range from 1.4−15.6 % [6, 21], and depends on the technique of pin insertion. In a recent trial by Lee et al. , the risk of iatrogenic ulnar nerve injury was 0–6.8 %. In our study, the risk was 6.5 % (2 cases) in the medial–lateral entry group—one case showed only paraesthesia along the ulnar nerve distribution, which subsided spontaneously within one week while the other case of nerve palsy with both motor and sensory deficits, showed complete neurological recovery after 4 months. The incidence of ulnar nerve injury in our study was low because of precautions such as inserting the lateral pin first, avoiding hyperflexion of the elbow during medial pin placement and by retracting the nerve more posteriorly by the digital method before medial pin insertion. The risk of iatrogenic ulnar nerve injury can be further reduced with a mini medial incision as reported by Kocher et al.  and with extension of the elbow during medial pin placement. Iatrogenic ulnar nerve injuries associated with medial pin fixation resolve after replacement of the medial pin at a new location , as occurred in our two cases.
In our study, the difference with regard to the loss of range of movement between the two groups was statistically insignificant (P = 0.51), with both groups showing an excellent or good range of movements. The functional outcome following medial and lateral pinning was excellent in 83 % and good in 17 % of cases. There were no poor results, while cases treated with lateral pinning showed 74 % excellent and 26 % good results with no poor results. Similar results were shown by Kocher et al. , Mostafavi and Spero , and Aronson and Prager . The difference in functional outcome between the two groups in our study was not statistically significant (P = 0.53).
One of the strengths of this study was being a prospective randomized clinical trial with the patients randomized at the time of fracture treatment. Furthermore, both the lateral entry and the medial–lateral entry techniques were standardized in terms of pin size, pin location, and the position of the elbow for medial pin placement. Full clinical and radiographic evaluation was performed at regular intervals. The major limitation of the study was the small number of cases in each group. A randomized controlled trial (possibly triple blind) involving a large number of patients with long-term follow-up is clearly needed to clarify the differences between the two techniques.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
(1) All patients provided informed consent prior being included into the study. (2) All procedures involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments. (3) The study was approved by the Research Ethics Committee.
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