Research Article: Non-rotational medial pinning with the K-Hammer technique in pediatric supracondylar fractures: a retrospective case-control study
Abstract:
Pediatric Gartland type III–IV extension-type supracondylar humeral fractures are associated with a risk of iatrogenic ulnar nerve injury during medial percutaneous pin insertion. The optimal technique for medial pin placement during crossed pin fixation remains debated.
A retrospective case-control study was conducted involving 80 pediatric patients treated between September 2020 and September 2025. All patients had isolated closed extension-type Gartland III–IV supracondylar humeral fractures treated with two lateral and one medial crossed K-wires, with a minimum follow-up of 6 months. Patients were divided into the K-Hammer group, in which medial pinning was performed using a non-rotational K-Hammer-assisted technique with the elbow in 30°–60° extension, and the Freehand group, in which medial pinning was performed using conventional low-speed drilling with the elbow flexed at 90°. The primary outcome was symptomatic iatrogenic ulnar nerve injury within 2 weeks postoperatively. Secondary outcomes included medial pin attempts, operative time, radiographic alignment, elbow range of motion, Flynn functional grade, and postoperative complications.
The K-Hammer group had significantly fewer medial pin attempts [1.0 (IQR: 1.0–1.0) vs. 2.0 (IQR: 1.0–2.0), P <?0.001] and shorter operative time (32.8?±?6.9 vs. 37.9?±?9.2?min, P =?0.006). Intraoperative pink pulseless hand rates were comparable (10.5% vs. 4.8%, P =?0.416), and all patients recovered radial pulse postoperatively. Iatrogenic ulnar nerve injury occurred in 0% (0/38) of the K-Hammer group vs. 11.9% (5/42) of the Freehand group ( P =?0.056), corresponding to an exploratory absolute risk reduction (ARR) of 11.9% and a number needed to treat (NNT) of approximately 8.4. No secondary displacement or reoperation occurred in either group. Pinsite infection and myositis ossificans rates were low and similar. At a median follow-up of 7.5 months (IQR: 6.2–11.8; range: 6–36 months), radiographic and functional were comparable between groups.
The K-Hammer technique improves operative efficiency, reduces pin insertion attempts, and demonstrates a favorable trend toward reduction in iatrogenic ulnar nerve injury risk (ARR 11.9%, NNT?=?8.4), without compromising radiographic or functional outcomes. Although statistical significance was not reached ( P =?0.056), likely due to limited sample size, these findings suggest it is a potential technical option for medial pin placement in severe pediatric supracondylar humeral fractures, warranting confirmation in larger prospective studies.
Introduction:
Pediatric Gartland type III–IV extension-type supracondylar humeral fractures are associated with a risk of iatrogenic ulnar nerve injury during medial percutaneous pin insertion. The optimal technique for medial pin placement during crossed pin fixation remains debated.
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