Modified percutaneous Kirschner wire with mutual linking technique in proximal humeral fracture: a technique note and preliminary results


 Background: The percutaneous pinning technique (PPT) with multiple Kirschner wires (K-wires) is one of common surgical options in proximal humeral fractures. However, complications including pin migration and loss of reduction have been re-ported. We aimed to describe a novel technique employing modified percutaneous pin-ning with mutual linking for the treatment of proximal humerus fractures, which may decrease such complications. Methods: 6 patients (5 female, 1male ; mean age 60.1 years) received close reduction and the modified percutaneous Kirschner wire fixation with mutual linking technique. All wires were removed about 6 weeks postoperatively followed by progressive reha-bilitation. We used following radiograph to evaluate bony union, wires migration, and fragment displacement. Clinical outcomes were evaluated using range of motion of af-fected glenohumeral joint, a 1-10 visual analog score (VAS), UCLA shoulder rating score (UCLA), and the American Shoulder and Elbow Surgeons Shoulder Score (ASES). Outcomes were evaluated during the 2-month follow up and at the final follow up. Results: All cases were followed-up after an average of 12.6 months (range, 12-13.5 months). The mean of anterior forward flexion of the injured shoulder were 152.5 degrees (range, 145-160 degrees) during the 2-month follow up and 166.7 degrees (range, 150-180 degree) at the final follow up respectively. The means of the VAS, UCLA score, and the ASES of the injured shoulders were 0.3 (range, 0-1), 31.8 (range, 27-34), and 92.4 (range, 82-100) respectively. No wire migrations or fracture displacements were noted in our cases. There were also no deep infection, nonunion, implant failure, or avascular necrosis of the humeral head observed during the follow-ups. Conclusions:With this modified percutaneous Kirschner wire mutual linking technique, minimal invasive approach could be achieved and additional stability was provided by mutually linking the wires to reduce pin migration and fracture displacement in proximal humeral fracture.

technique, minimal invasive approach could be achieved and additional stability was provided by mutually linking the wires to reduce pin migration and fracture displacement in proximal humeral fracture.

Surgical Procedure
After general anesthesia or brachial plexus block, the patient was placed in the beach-chair position. The injured extremity was prepared, draped, and freely movable. Close reduction of the fracture was achieved by manual traction and gentle manipulation; and when needed, additional wires were used as joysticks or the Kapandji technique was applied in case of difficult reductions. The fixation technique was adapted from Jaberg's technique using four to six K-wires (diameter 2-2.5mm), depending on the fragments [3] (Figs. 1-3). After reduction, two parallel wires were inserted through the greater tuberosity and anchored to the medial cortex of the humeral shaft through the fracture site; the other two parallel wires were inserted from the lateral cortex of the humeral shaft and anchored to the subchondral bone of the humeral head. Two additional parallel wires were inserted from the lateral cortex of the humeral shaft to the calcar area to provide additional stabilization (Fig. 4). Several intramedullary wires could also be applied in cases where the reduction is difficult to maintain. After K-wire application, all wires were bent at a position about 1cm above the skin to prevent skin irritation, and then mutually hooked with adequate tension as a universal construct. The K-wires were then cut at appropriate lengths with a wire cutter (Figs.1d, e, Fig. 2d). The tension of the wires' links was considered adequate if no loosening was noted after applying a gentle passive range of motion of the injured shoulder. Additionally, stability of the wires' links can be augmented using cerclage rubber bands at the connection sites (Fig. 5).

Postoperative Rehabilitation
The shoulder was then immobilized with an arm sling for 4 weeks following surgery, after which all wires were removed contingent on the radiograph exam (Figs. 1c, 2c, and 3c). Patients were encouraged to start a passive pendulum exercise after removal of the wires. Assisted or active exercise without resistance was encouraged after diagnosis of radiological healing (usually 6 weeks postoperatively).

Outcome measures
We used following radiograph to evaluate bony union, wires migration, and fragment displacement. Postoperative clinical outcomes were evaluated using range of motion of affected glenohumeral joint, a 1-10 visual analogue score (VAS) for pain assessment, UCLA shoulder rating score (UCLA) [20], and the American Shoulder and Elbow Surgeons Shoulder Score (ASES) [21]. Outcomes were evaluated during the 2-month follow up and at the final follow up.

Statistical analyses
All parameters were analyzed statistically. Data are presented as mean and range.

Results
We identified 6 consecutive patients (5 women and 1 man; mean age 60.1 years; age range 16-79 years) with displaced proximal humeral fracture received close reduction and the modified percutaneous Kirschner wire fixation with mutual linking technique. All 6 patients had been injured in either a traffic accident or a simple fall (Table 1). Radiographic bony union were noted in all cases 6 weeks after surgery, and all cases were followed-up after an average of 12.6 months (range, 12-13.  (Table   1). There were no wire migrations or fracture displacements noted in our cases.
There were also no deep infection, nonunion, implant failure, or avascular necrosis of the humeral head observed during the follow-ups.

Discussion
There are various treatment options for proximal humeral fractures. Although the PPT has advantages associated with minimally invasive surgery, it is sometimes difficult to achieve anatomical reduction with the PPT compared to open reduction and internal fixation (ORIF) [12]. Close reduction is very difficult to achieve anatomical reduction but suboptimal reduction. Nevertheless, several studies have revealed that satisfactory clinical results can be obtained despite suboptimal reduction of the fracture, particularly in the elderly [3,[22][23][24]. Similar results were also founded in our study [ Fig.1-3]. Some complications related to the PPT have been reported, including pin migration [3,16,17] leading to serious complications [25,26], loss of reduction [3,18,19], infection and arm-length discrepancy in children [24,25].
Some efforts have been dedicated to decreasing the wire-migration rate and enhancing the stability of the pinning fixation via the use of a locking device applied to the pins (Table 2) [11,12,27]. One such locking device is called the "Humerus block", in which two crossed K-wires at the fracture site are held at a fixed angle with the block and locking screw. Additional percutaneous screws can be inserted for the fixation of other fragments [11]. Another device, Minimally Invasive Reduction and Osteosynthesis System, also called "MIROS", involves placing four pins through the fracture site and then blocking with a metallic clip above the skin [12]. A third method is called the "Hybrid technique", in which open reduction is performed and K-wires are applied and secured by an external fixator [27]. All these semi-rigid instruments achieve satisfactory clinical and radiographic outcomes, and generally have lower complication rates, lower revision rates, and lower rates of pin migration than the PPT alone [12,27]. Moreover, the rationale of these techniques is to augment pin stability and structural strength via an external locking instrument. However, only a limited number of K-wires can be used in the humerus block and MIROS devices; namely, two wires for the humerus block and four wires for the MIROS device. Another limitation is the fixed direction for anchoring the Kwires in the locking device. Unfortunately, these limitations may lead to insufficient fragment fixation. The hybrid technique, combining multiple K-wires and an external fixator, can offer additional fixation points for the fragments; however, the bulky external fixator is the major concern. In contrast, our modified technique has the advantage of sufficient K-wires with freedom of direction and position to fix multiple fragments. The construct is smaller and more cost-effective than previous devices.
In addition, the bending and mutual linking of the wires can provide additional valgus force to resist the deforming force from the deltoid and supraspinatus muscles; however, further biomechanical studies are needed to confirm this point.
There are some possible disadvantages of our technique, including pin-tract infection and immobilization in the early postoperative period. Nevertheless, we expect benefits including improved clinical outcomes, less pin migration, better stability of fragment fixation, and less overall complications compared to the PPT.
We have already performed this technique on 5 patients, in whom no wire migration or fracture displacement were noted with the mutually linked K-wires. Accordingly, we believe that this technique could also be applied to other fracture fixations, such us distal radio-ulnar fracture, as well as metatarsal and metacarpal bone fractures.

Consent for publication
Not applicable

Availability of data and materials
The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests.

Funding
The authors received no financial support for the research, authorship, and/or publication of this article.  Schematic of the percutaneous Kirschner wires with mutual linking technique for proximal hu Figure 5 Cerclage rubber bands were used at the connection sites to augment the stability of the wire