Biomechanical evaluation of a modified proximal humeral locking plate application for distal extra‐articular diaphyseal humeral fractures

Abstract

The extra-articular distal humerus locking plate (EADHP) is widely used for distal extra-articular diaphyseal humeral fracture fixation. However, it occasionally causes skin prominence and discomfort. The upside-down use of a proximal humerus internal locking system (PHILOS) plate is suggested as an alternative option, but it lacks biomechanical evidence. The purpose of this study was to compare the biomechanical performance between two different fixation methods: the modified use of the PHILOS plate on the anterior cortex versus conventional use of an EADHP on the posterior cortex. Twelve pairs of fresh-frozen cadaveric humeri were used and 7 mm gap osteotomy was performed at 50 mm proximal to the lateral epicondyle to simulate an AO/OTA 12-C1.3 fracture type. Single load to failure was measured after five stiffness tests of the plate-bone constructs in anterior/posterior bending, internal/external torsion, and axial compression. There were no significant differences in metrics between the two groups, except for the load to failure in posterior bending, which was significantly higher for PHILOS (1589.3 ± 234.5) compared to EADHP (1430.1 ± 188.6), p < .023. In conclusion, the modified use of the PHILOS plate showed comparable biomechanical performance compared to the conventional EADHP. The new fixation method offers potential clinical advantages, considering the patient's position and surgical approach at the time of surgery as well as postoperative soft tissue irritation. Therefore, this could be an option for distal humeral extra-articular diaphyseal fracture fixation when the use of EADHP is not suitable or preferred.

Biomechanical performance evaluation of a modified proximal humerus locking plate for distal humerus shaft fracture using finite element analysis

“…The simulation results of the EADHP and PHILOS are summarized in Table 3 . As in a previous biomechanical study using cadavers 18 , the EADHP and PHILOS exhibited adequate biomechanical performance and stability under axial, bending and varus load conditions. The maximum von-Mises stress of the EADHP on the plate was 300.54 MPa under the axial force, while those of the PHILOS were 109.62 MPa and 83.63 MPa on the humerus under the bending and varus forces, respectively.…”

“…In the 30 mm space, at least four locking screws can be used to perform distal fixation on the anterior plating with the PHILOS. The 10 mm gap was aimed at causing extreme instability in a biomechanical DHSF model 14 , 18 .…”

“…However, concerns have been raised about unstable fixation because of fixation directly above the coronoid fossa. Lim et al 18 reported that anterior plating with a modified proximal humerus locking plate (PHILOS; DePuy Synthes Inc.) exhibited a fixation and biomechanical performance comparable to that of posterior plating with the EADHP in bending, torsion, and compression force. Sohn and Shin 22 suggested anterior plating with a modified PHILOS as an alternative treatment for a DHSF.…”

Modified medial minimally invasive plate osteosynthesis techniques for the treatment of distal third diaphyseal fracture of humerus using a double plate technique

“…Immobilization is often required in the early postoperative period, thus losing the opportunity of early functional exercise. Many studies [17,18] have shown through biomechanical analysis that a single plate is suitable for fracture types of the middle and upper part of the humerus, while a double plate and double column xation can provide better antibending and anti-torsion forces for fractures of the distal humerus. Since the fracture characteristics of the distal third diaphyseal fracture of the humerus determine if the distal end of the fracture is xed with a single plate, it is di cult to achieve with three screws and six cortical xations, and therefore, the xation can be unstable.…”

Anatomic fit of precontoured extra-articular distal humeral locking plates: a cadaveric study

“…The cutoff value was 60.5 mm for distal humeral width, which corresponds to a sensitivity of 100% and a specificity of 81.8%. pared to EADHP [21]. Yin et al [22] suggested both an anterolateral approach and a lateral approach to distal humeral extra-articular fractures as alternative surgical methods.…”