Percutaneous Pinning of Proximal Humerus Fractures

Edward J. Harvey M.D., MSc, FRCSC
Montreal, QC

The myriad of treatment protocols for the proximal humerus fracture means only one thing - this fracture is probably inadequately treated by all modalities1. Percutaneous pinning is possible in almost all fractures of the proximal humerus. Certain steps must be taken in order to ensure the success of the fixation. Bouquet fixation, or the use of flexible nailing systems, are possible choices but these have been associated with frequent complications. A systematic approach (similar to that of Jaberg et al2) to both the reduction of the fracture through stab incisions and the placement of 2.5 mm wires will maximize chances of success. The implant of choice is the 2.5 mm terminally threaded k-wire (easily obtainable from the AO small external fixators set).

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Figure 1a Typical axillary view of comminuted proximal humerus fracture in a 65 year old male. Mechanism of injury was a fall from 2nd floor roof.

 

 The patient is placed on either a Jackson table or a conventional table with an adjustable arm board. If the conventional table is used, the fluoroscan is set up parallel to the table entering from the head. The arm board is abducted 45 degrees so that a lateral shot through the axilla can be obtained. Sometimes severe comminution is better appreciated with this view (Figure 1a).Reduction of even a dislocated shoulder can be carried out through multiple stab incisions through the deltoid less than five centimetres distal to the acromion. Final reduction of the shaft angle to the head is usually obtained at 45 degrees of shoulder flexion. The first step in reduction is the head to the shaft to reform the calcar as anatomically as possible.

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Figure 1b Orthogonal view reveals a head splitting fracture (arrow) which may persuade the surgeon to perform hemiarthroplasty for this fracture. Because of the relative small displacement apparent, and the patients desire to remain an active person, a percutaneous pinning was carried out as per the text.

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Figure 2 Final fixation of the fracture with percutaneous k-wires. The calcar has been reduced. Because of comminution, the inferior wires (large arrow) are placed just at the shaft fracture margin. This prevents migration of the head inferiorly. The greater tuberosity wires are through the cortex on the medial shaft (multiple small arrowheads). A wire is driven to the subchondral surface of the head (single small arrow). This is a safe placement of the wire if the final tightening is done by hand and the wire has not been backed out (even a half turn) in order to obtain this position. This wire was placed as a fifth wire because the four other wires were inferior to the head halfway point.

Sometimes due to comminution, the k-wires aid in giving some biomechanical support to the calcar (Figure 2). This may leave a large gap laterally where the greater tuberosity must be reduced to prevent the head from falling back into valgus. The head is held to the shaft with four k-wires placed through a fluoroscan-guided quadrangle near the deltoid insertion. The lower k-wires are inserted first. These wires are advanced under power until they are five millimetres from the subchondral surface. They are then turned into the subchondral bone by hand. It is imperative that these wires are never backed out a few turns if they are into the joint space. If a wire has entered the joint, that k-wire must be completely removed and a new wire inserted. This is the only way to prevent migration in either direction. The two superior k-wires are inserted in the same way. Care must be taken during insertion to ensure that they do not block the reduction of the greater tuberosity. Depending on the fracture fragment size, these wires may be inferior in the head fragment. If they are below the midline of the head, thought must be given to a more inferior lateral starting point.

Assuming anatomic reduction of the calcar and head; the next reduction is the greater tuberosity. Wires are inserted posterior and superior into the tuberosity through stab incisions. The tuberosity can be manipulated with a Steinman pin on a T-handle. The wires are driven down the shaft of the humerus on the lateral view and stuck through cortex inferior to the calcar (Figure 2). Slow pressure on the power driver while at full speed will ensure cortical support rather than an intramedullary wire. If the wires are intramedullary they must be replaced. This is the support to prevent the head fragment from falling into valgus. The lesser tuberosity, if fractured, may be held in place with a single wire but the angle of the wire will increase risk to the neurovascular bundle. The wires at the greater tuberosity are bent to 90 degrees and cut one centimetre above the skin. They are removed in clinic in three to four weeks and the patient is not allowed to abduct the shoulder until that time. The wires at the deltoid insertion are cut below the skin as far as possible. Detumescence of the arm at six to eight weeks postop will allow easy identification of the pins for clinic removal.

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Figure 3 Radiographic postoperative result. Full ROM at four months was obtained in this motivated patient


References

1. Koval K.J., Blair B., Takei R., Kummer F.J., Zuckerman J.D. Surgical neck fractures of the proximal humerus: a laboratory evaluation of ten fixation techniques. J Trauma. 1996 May; 40 (5): 778-83.

2. Jaberg H., Warner J.J., Jakob R.P. Percutaneous stabilization of unstable fractures of the humerus. J Bone Joint Surg Am. 1992 Apr; 74 (4): 508-15.

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