Limited Dynamic Hip Screw for Treatment of Intertrochanteric Fractures: A Biomechanical Study

BACKGROUND: The aim of this article is to introduce a novel technique of limited dynamic hip screw (LDHS) in the treatment of intertrochanteric fractures and to evaluate its biomechanical effects. MATERIAL/METHODS: Based on the principle of providing both dynamic and static pressure to stabilize the fracture, we improved the dynamic hip screw (DHS) and designed the LDHS. Six fresh cadavers were collected and intertrochanteric fracture models were established, including Evan’s type I fracture (n=3) and type II (n=3). We used the left-to-right comparison in this study. LDHS technique was performed on the left femoral head of each cadaver (LDHS group: n=6), while DHS was performed on the right side (DHS group: n=6). After fixation by either LDHS or DHS, compressive strength, rigidity, shear stress and strain, torsional properties, and ultimate loads were measured and compared in both groups. RESULTS: Under the 1200 N pressure, compressive strength, rigidity, shear stress and strain, and ultimate loads of LDHS were better than those of DHS in the 2 groups. All differences were statistically significant. Although LDHS enhanced the torsional properties, there was no significant difference. CONCLUSIONS: Our study demonstrates that the biomechanical effects of LDHS are superior than those of DHS, and there was no screw failure after implantation. Armed with those better properties, LDHS, as a new internal fixation device, may be a good alternative option in the treatment of intertrochanteric fractures.