Minimally invasive dual incision with mini plate internal fixation improves outcomes over 30 months in 20 patients with Sanders type III calcaneal fractures

This study was approved by the Ethics Committee of our hospital, and all patients provided written informed consent to participate in the study and for all operative procedures performed.

Patients eligible for inclusion were those with a Sanders type III intra-articular calcaneal fracture and posterior subtalar articular displacement > 2 mm. Exclusion criteria were as follows: (1) open fractures accompanied by multiple injuries in the brain, chest, and/or abdomen; (2) computed tomography (CT) showing severe articular surface crushing that cannot be reconstructed; and (3) diabetes with blood glucose that is not well-controlled. Based on the above criteria, 20 patients received surgery and were included in the study.

All patients received CT scans of the injured foot, with a focus on the calcaneus, and also received preoperative calcaneal lateral and axial radiography. Fracture morphology and articular surface collapse were then evaluated by three-dimensional (3D) reconstruction to create an operative plan.

In all patients, the small lateral incision was planned to begin approximately 1.0–1.5 cm below the lateral malleolus tip, with slight extension centered on the tarsus sinus. The small medial incision was planned over the posterior tuberosity three fingers breadths below the medial malleolus. After administration of anesthesia, a thigh tourniquet was placed and inflated, and the skin of surgical area was sealed with surgical film. A small medial incision was made to expose the medial wall of calcaneus and sustentaculum tali. A small lateral incision was then made through the lateral tarsal sinus to expose the lateral calcaneal wall and to distract the tendon that protects the fibula and nervi suralis. The end of calcaneofibular ligament was sharply dissected to expose the rear surface of the subtalar joint. Two 1.5-mm Kirschner wires were inserted into the talar neck and bent to retract and protect the soft tissue. At this time, the condition of the fracture and collapse of the rear surface of the subtalar joint could be directly observed. A single 4.0-mm Steinmann wire was inserted transversely into the interior side of the calcaneus through the tuberosity of the calcaneus where the bone is thick. Subsequently, another 4.0-mm Steinmann wire was inserted transversely into the interior lower part of the tibia. A bone distractor was placed at the medial side via the Steinmann wire and then gradually distracted to reset the tuberosity of the calcaneus. In the course of this process, the tuberosity shifted up, with inversion backward to the lower part.

A miniature T-shaped bone plate was placed on the medial wall of the calcaneus, and the sustentaculum tali and the calcaneus tubercle were connected using a semi-cortical technique to fix the screws. Next, the lateral part of the articular surface was carefully distracted through the lateral incision of the calcaneus. A small bone pry was used to lift the middle bone block, which was collapsed into the posterior part of the calcaneus, using the medial part of the articular surface as a reference point. Two 1.2-mm Kirschner wires were fixed to and penetrated the sustentaculum tali. Then, the 2 Kirschner wires were retraced through the medial incision until the end of Kirschner wire was level with the bone surface. After repositioning the lateral articular surface and confirming that the articular facet was flat, two 1.2-mm Kirschner wires were introduced in parallel under the extrovert articular surface.

The anterior bone mass of the calcaneus was reduced and temporarily fixed with Kirschner wires at the position of the sustentaculum tali. To restore the width of the calcaneus, sideway extrusion was performed on the lateral portion of the calcaneus. One guide wire was introduced in the calcaneal tubercle from the lateral back lower portion to the medial front upper portion until the sustentaculum tali was reached. Another guide wire was drilled through the calcaneal tubercle from the upper medial back portion to the lower lateral front portion until the forepart of the calcaneus was reached. A 7-hole 2.5-mm plastic mini locking plate was shaped, and then inserted through the small lateral incision, slide along the lower edge of the articular surface of the calcaneus, and finally placed on the lateral side of the calcaneus. Multiple screws were placed at the lower part of the posterior articular surface of the calcaneus and the anterior portion of the calcaneus, and two 5-mm fully threaded cannulated screws were inserted through the previous two guide wires. One cannulated screw was fixed from the calcaneus tubercle to the anterior part of the calcaneus, and the other one was fixed from the calcaneus tubercle to the sustentaculum tali. For patients with a tongue-type fracture, a 4.0-mm fully threaded cannulated screws were used for fixation perpendicular to the fracture line.

After confirming reduction of the fracture and the length of the internal fixtures were appropriate by fluoroscopy, the operative area was flushed with saline solution. Bone allograft (Osteolink Co., Ltd., China) was placed based on the size of bone defect after fracture restoration. The incisions were closed in layers, and one indwelling rubber drain was placed in each wound.

Postoperative patients were scheduled for re-examination at 1, 2, 3, 6, 12, 18, 24, 30, and 36 months after surgery. Healing of the incisions was observed, and any complications were addressed. The quality of fracture reduction was evaluated by radiographs and CT. The Böhler angle, Gissane angle, and the length, width, height, and articular surface steps were recorded preoperatively, postoperatively, and at the final follow-up. The American College of Foot and Ankle Surgery (AOFAS) score was used for evaluation of functional outcomes [14]. A visual analogue scale (VAS) pain score was used to evaluate all patients. Functional outcomes and complications were assessed and recorded by an independent surgeon who was unaware of the study design.

Twenty patients, 16 males and 4 females, with a mean age of 39.75 ± 11.59 years, received surgery and were included in the study. In 95% of the patients, the mechanism of injury was a fall from height. Seven patients had left side fractures, and 13 right side fractures. Based on Tscherne soft tissue injury score, 13 patients were closed fracture grade I, and 7 patients were closed fracture grade II. The average time between hospital admission and surgery was 6.75 ± 3.26 days. The main reasons for the extended time were soft tissue swelling, comorbidities, and in some cases patients taking anticoagulant drugs. The mean follow-up period was 41.95 ± 4.41 months (Table 1).

As compared to the preoperative values, the calcaneal width and articular surface decreased after surgery, whereas the Böhler angle, Gissane angle, and calcaneal height and length increased after the surgery (Table 2). The mean Böhler angle increase was 48.60°; the mean Gissane angle increase was 25.00°; the mean calcaneal height increase was 14.17 mm; the mean calcaneal length increase was 2.05 mm; the mean calcaneal width decrease was 11.11 mm; the mean articular surface decrease was 5.45 mm (all, p < 0.01). Importantly, there were no significant differences in the aforementioned variables between those measured postoperatively and those measured at the final follow-up (data on file).

Preoperative and 40-month postoperative radiographs, CT images, and measurement of a representative case are shown in Figs. 1 and 2. Of note, as compared to the preoperative values, the calcaneal width and articular surface decreased after surgery, whereas the Böhler angle, Gissane angle, and calcaneal height and length increased after the surgery.

Based on AOFAS hindfoot scores, 7 patients (35%) had excellent results and 9 (45%) good results; thus, 80% of patients had good or excellent outcomes. Three (15%) patients had fair scores, and 1 (5%) patient had a poor score. The mean AOFAS score was 82.5 points (Table 3). The mean postoperative VAS pain score was 1.6 ± 1.35.

There were 8 postoperative complications: 6 cases of screw positioning deviation, 1 malunion, and 1 case of delayed wound healing. There were no postoperative wound infections.