Locking plating is the most common operation for displaced proximal humerus fractures in active patients, and it is one of the least forgiving. The humeral head is a small ball of cancellous bone held by tuberosity fragments under rotator cuff pull, and the margin for error is measured in millimeters: a plate a few millimeters too high impinges under the acromion, a screw a few millimeters too long penetrates the joint, and a missing calcar screw lets the head drift into varus and take the construct with it. This guide walks through the technique using the proximal humerus plating systems we supply at BoneCraft as the hardware reference. Every final decision rests with the operating surgeon.
Fracture assessment and planning
True AP and axillary or scapular-Y views define the parts; a CT scan clarifies head-split fragments and the position of the articular segment. Planning answers four questions before the incision: how many parts are displaced, whether the medial calcar hinge is intact or disrupted, the bone quality of the humeral head, and whether the pattern is fixable at all — fracture-dislocations with head-splitting in elderly low-demand patients may be better served by arthroplasty, a decision made by the treating surgeon. Fixable patterns proceed to open reduction and locking plate fixation.
The deltopectoral approach
The patient is in beach-chair position with the arm draped free and a C-arm coming over the top. The incision runs from the coracoid toward the deltoid insertion along the deltopectoral groove, and the cephalic vein is taken with the deltoid. The clavicopectoral fascia is released, the conjoint tendon is retracted medially, and the fracture site is exposed without stripping the soft tissue envelope around the tuberosities — the blood supply to the humeral head travels through these attachments, and devitalized fragments collapse no matter how well they are plated. The long head of biceps serves as the orientation landmark between the greater and lesser tuberosity.
Reducing the head and the tuberosities
Heavy non-absorbable sutures are passed through the rotator cuff insertions on each tuberosity fragment — the cuff, not the bone, is what holds tension. The humeral head is reduced to the shaft first, restoring the medial cortical contact and the neck-shaft angle; a small elevator or joystick through the fracture line lifts a disimpacted head. The tuberosities are then brought down around the head and held provisionally with K-wires. Restoring the medial calcar — either by anatomic cortical contact or by stable impaction — is the mechanical foundation of the whole construct, because a head floating without medial support will drift into varus under load.
Plate position: the two millimeter rules
The locking plate is placed on the lateral aspect of the proximal humerus, posterior to the bicipital groove to spare the ascending branch of the anterior humeral circumflex artery. Two positional rules govern placement: the upper edge of the plate sits below the tip of the greater tuberosity — five to eight millimeters is the usual teaching — to avoid subacromial impingement; and the plate must sit distal enough that its divergent proximal screws still find the center of the humeral head. Position is confirmed under fluoroscopy before the first screw, because every later step inherits the plate position.
Screw and peg placement in the head
The shaft is fixed first through the slotted hole, which permits small height corrections. Head fixation then follows the system design: threaded locking screws for purchase in reasonable bone, smooth locking pegs where gentler fixation or later removal matters. The decisive screw is the calcar screw, directed from the plate up into the inferomedial quadrant of the head, close to the subchondral bone of the medial calcar. Biomechanical studies and clinical series agree that this screw is the main defense against varus collapse. BoneCraft stocks the proximal humerus locking plate for the locking construct, the proximal humerus plate with smooth locking pegs for the traditional peg construct, and smooth locking pegs across the range — all under the shoulder and humerus collection.
Checking for joint penetration
Screw length in the humeral head is checked by feel and by fluoroscopy, and neither alone is enough. Screws are placed slightly short of the subchondral bone — two to five millimeters — and the head is then screened through a full arc of rotation on multiple views, because a screw hidden on one projection appears clearly inside the joint on another. Any penetrated screw is exchanged before closure. This check matters twice: primary penetration at the table, and secondary penetration later if the head collapses onto screws that were placed too long.
Closure and aftercare
The tuberosity sutures are tied through the dedicated suture holes of the plate, adding soft-tissue fixation that unloads the screws. The wound is closed in layers over a drain where required. Passive pendulum motion begins early under the protocol set by the operating surgeon; active motion follows radiographic healing, and strengthening waits for solid union. The fixation goal is a construct stable enough for early motion without loading the head screws to failure.
The failure modes worth preventing
Three complications dominate the literature. Varus collapse follows a missing medial support — an unreduced calcar or an absent calcar screw. Screw cut-out and secondary joint penetration follow screws placed too long in a head that later settles. Subacromial impingement follows a plate placed too high. Each is a technique problem with a technique answer: restore the medial hinge, place the calcar screw, set screws short and verify on rotation views, and respect the plate height rule.
Sourcing proximal humerus plating systems
BoneCraft is an independent distributor of genuine Zimmer Biomet trauma implants, including the proximal humerus plating families referenced in this guide. Hospitals and distributors who need locking plates, peg constructs and calcar screws from stock can contact our team for availability and lot documentation.
Frequently asked questions
Which approach is standard for proximal humerus plating?
The deltopectoral approach. It preserves the deltoid and the soft tissue attachments of the tuberosities, through which the humeral head draws its remaining blood supply. An anterolateral deltoid split is the alternative for selected patterns.
How high should the plate sit on the humerus?
The upper edge stays below the tip of the greater tuberosity, commonly five to eight millimeters below, to avoid subacromial impingement while still letting the proximal screws reach the center of the humeral head.
What does the calcar screw do?
It runs from the plate into the inferomedial quadrant of the head, supporting the medial calcar region. It is the principal defense against varus collapse, the most common mechanical failure of proximal humerus plating.
How is screw penetration of the joint ruled out?
Screws are placed slightly short of subchondral bone and the head is screened through a full rotation arc on multiple fluoroscopy views. A screw that looks safe on one projection can appear inside the joint on another, so single-view checks are not accepted.
Are smooth pegs or threaded screws used in the humeral head?
Both are valid. Threaded locking screws give purchase in reasonable bone; smooth locking pegs are gentler on soft cancellous bone and easier to remove. The choice follows bone quality and the system design, judged by the operating surgeon.
Why are sutures tied through the plate?
The rotator cuff sutures placed in the tuberosities are tied through the plate suture holes, adding soft-tissue fixation that holds the tuberosities against pull and unloads the bone screws.
When can the shoulder move after plating?
Passive pendulum exercises usually begin within days under the surgeon's protocol. Active motion waits for early radiographic healing and strengthening for solid union; the schedule is set by fixation quality and fracture pattern.
Zimmer Biomet and ZPLP are trademarks of their respective owner. BoneCraft is an independent distributor of genuine Zimmer Biomet products and is not affiliated with, sponsored by, or endorsed by the trademark owner.
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