Lack of fifth anchoring point and violation of the insertion of the rotator cuff during antegrade humeral nailing

Abstract

Antegrade nailing of proximal humeral fractures using a straight nail can damage the bony insertion of the supraspinatus tendon and may lead to varus failure of the construct. In order to establish the ideal anatomical landmarks for insertion of the nail and their clinical relevance we analysed CT scans of bilateral proximal humeri in 200 patients (mean age 45.1 years (sd 19.6; 18 to 97) without humeral fractures. The entry point of the nail was defined by the point of intersection of the anteroposterior and lateral vertical axes with the cortex of the humeral head. The critical point was defined as the intersection of the sagittal axis with the medial limit of the insertion of the supraspinatus tendon on the greater tuberosity. The region of interest, i.e. the biggest entry hole that would not encroach on the insertion of the supraspinatus tendon, was calculated setting a 3 mm minimal distance from the critical point. This identified that 38.5% of the humeral heads were categorised as 'critical types', due to morphology in which the predicted offset of the entry point would encroach on the insertion of the supraspinatus tendon that may damage the tendon and reduce the stability of fixation. We therefore emphasise the need for 'fastidious' pre-operative planning to minimise this risk.

Displaced proximal humeral fractures: When is surgery necessary?

“…As mentioned above, these results could be explained by the additional damage to rotator cuff tendons caused by the insertion of PHN in older individuals [22,23]. Accordingly, the use of PKW could be a better option than PHN in older patients.…”

“…Elderly patients with debilitated rotator cuff tendons could be less tolerant to the iatrogenic injuries caused by the anterograde surgical approach used in PHN. In addition, poor bone quality in elderly individuals could also condition the mechanical stability of proximal humeral fractures leading to deficient primary fixations and implant failure [22,23]. These factors could explain why PHN seems to achieve better results in younger individuals.…”

Biomechanical evaluation of straight antegrade nailing in proximal humeral fractures: the rationale of the “proximal anchoring point”

“…1) [5]. -The medialization of the proximal part of the nail within the humeral head preserves a larger amount of bony substance lateral to the nails rim (Blateral bony bridge^), additionally increasing the constructs capability to resist varus displacing forces (Fig.…”

“…Although this concept of the Bproximal anchoring point( PAP) has been described in the literature, its potential biomechanical advantage has never been biomechanically proven [5].…”

Clinical outcomes and prognostic factors depending on implant design in the treatment of proximal humeral fractures: A retrospective study

“…However, since curved nail designs are associated with several complications (e.g., iatrogenic greater tuberosity fracture, varus malalignment related to a lateral entry point or a violation of supraspinatus on a greater tuberosity), a straight intramedullary nail design was developed to minimize these complications and catch the densest part of the humeral head. 5,6 Currently, different designs of nails are used, but there are few reports on outcome in comparative studies on the intramedullary nail design. 5 The aim of this study was to examine the clinical outcome of proximal humeral fractures treated surgically with two different shapes of intramedullary nails, and to determine the prognostic factors that affect these outcomes, with a focus on the specific fracture location.…”