From March 2017 to September 2019, 31 patients with intra-articular calcaneal fractures who had met our inclusion criteria were treated with external fixator-assisted reduction and percutaneous screw fixation at our hospital.
The inclusion criteria were as follows: 1) age between 18 and 60 years; 2) unilateral intra-articular calcaneal fractures; 3) Sanders II–III fractures; and 4) surgical treatment involving external fixator-assisted reduction and percutaneous screw fixation.
The exclusion criteria were as follows: 1) childhood fracture, osteoporotic fracture, or pathological fracture; 2) bilateral calcaneal fractures; 3) multiple injuries or compound injuries, such as pelvic fracture, spinal cord injury, chest and abdominal injury, burns, etc.; 4) old fractures; and 5) absence of informed consent from patients and their families.
This retrospective study was approved and authorized by the Ethics Committee of the Fourth Medical Center of PLA General Hospital. The description of surgical technique, informed consent, surgical mechanism, expected therapeutic effect, potential risk, and iatrogenic injury was approved.
Bastiani external fixator (Xinzhong Medical Instrument Co., LTD., China), self-tapping cortical bone screws with a diameter of 3.5 mm, and cannulated screws with a diameter of 3.0 mm or 4.0 mm (Johnson (Shanghai) Medical Devices Co., Ltd., USA) were used.
The type of intra-articular calcaneal fractures were classified according to the Sanders classification. A personalized treatment plan was developed for each patient. A patient with Sanders IIab (Fig. 1) is used as an example to describe the technical notes regarding the treatment of calcaneal intra-articular fractures with external fixator-assisted reduction and percutaneous screw fixation.
Preoperative computed tomography (CT) (Philips Medical Technologies, The Netherlands) with a thickness of 1.25 mm was used to scan the bilateral calcaneus and endoplants. Cortical bone and cannulated screws of different sizes were placed beside next to the heel during examination. The image was converted into Digital Imaging and Communications in Medicine format (DICOM) and downloaded and imported into the Mimics V16.0 software system. Taking the shape of the healthy calcaneus as reference, the system was used to simulate reduction of the mess fracture blocks and the subtalar articular surface (Fig. 2). Cortical bone screws or cannulated screws were placed parallel from the exterior to the interior below the subtalar articular surface, and at least two screws were used to fix each mess fracture. The following parameters were recorded during the simulated reduction and fixation process: the direction and distance of the traction reduction of the main fracture block; direction of elevating compressed subtalar articular surface; and position, direction, and size of the inserted screw for reference during the operation.
After general or epidural anesthesia, the patient was positioned on a fluoroscopic table in a lateral position with the injured limb on top; a tourniquet was not required. The G-arm fluoroscopy machine was placed diagonally under the fluoroscopy bed and adjusted to the appropriate position so that the lateral, axial, and Broden projection fluoroscopy could be conveniently carried out during the operation (Fig. 3).
Step 1: Reduce the calcaneal length and height and correct calcaneal varus or valgus (Fig. 4).
Before the surgery, the insertion points of external fixator needles in the talus and calcaneus were located under fluoroscopy. Then, an arc-shaped incision of approximately 2 cm was made at lateral calcaneus, and a part of the lateral calcaneus cortex was exposed by periosteal elevator. Then, two K-wires with a diameter of 3.0 mm were inserted parallelly into the calcaneus and talus according to the positioning of the insertion point. Then, bilateral external fixator was installed on the K-wire. According to the traction direction and distance obtained in the Mimics V16.0 software system before surgery, the bilateral nuts of external fixator were tightened to reduce the length and height of the calcaneus under radiological monitoring. The nut of unilateral external fixation was loosened or continuously tightened to correct calcaneal varus or valgus.
Step 2: Reduce the subtalar articular surface and percutaneous screw fixation (Fig. 5).
A 0.5-cm fissure was opened from the lateral calcaneal incision of the cortical bone, and a periosteal elevator was used to elevate the compressed subtalar articular surfaces. After the anterior, middle, and posterior articular surfaces of the subtalar joint were reduced under radiological supervision of border projections, K-wires were used for temporary fixation. Then, under radiological monitoring, two cannulated screws were implanted from the calcaneal tubercle toward the calcaneocuboid joint, one cannulated screw was implanted from the calcaneal tubercle toward the subtalar joint to maintain the calcaneus length and height, and two cortical bone screws were implanted below the subtalar articular surface to fix the subtalar joint fracture
Step 3: Reduce the calcaneus width and percutaneous screw fixation.
Point contact reduction forceps was placed on the medial and lateral walls of the calcaneus, or both hands were used to compress the calcaneus to reduce the width of the calcaneus. Then a cortical bone screw was inserted from the lateral of calcaneus into the sustentaculum tali to maintain the width of the calcaneus. Before the end of the operation, lateral, axial, and border projection radiographs of the calcaneus were retaken to confirm whether the reduction and fixation were satisfactory. Then, the external fixator was removed, and the wound was sutured.
Active toe flexion and extension, active ankle flexion and extension, active pronation and inversion, and passive subtalar pronation and inversion activities were performed immediately after surgery. Non-weight-bearing ambulation was begun on the second day postoperatively and partial weight-bearing ambulation at 6 weeks postoperatively. If the calcaneal fracture had healed, the patient could begin full weight-bearing ambulation at 3 months after surgery.
The time from injury to surgery and the duration of hospital stay were recorded. The operative time, amount of intraoperative blood loss, and changes in surgical procedures were recorded. After surgery, the patient was observed for wound infection, necrosis and sural nerve injury, etc.. Bilateral lateral and axial calcaneus radiographs, and bilateral calcaneus CT was performed before surgery. Lateral and axial radiographs, and CT of the injured calcaneus were performed on the second day, at 6 months after surgery and at the last follow-up. The length, height, width, Böhler angle, and Gissane angle of calcaneus were measured by radiography, and the reduction of the subtalar articular surface was observed by CT. According to the subtalar articular surface reduction criteria proposed by Kurozumi et al., no step, no defect, or no angulation was considered excellent reduction; step < 1 mm, defect < 5 mm, or angulation < 5° was considered good; step 1–3 mm, defect 5–10 mm, or angulation 5–15° was considered fair; and step ≥ 3 mm, defect ≥ 10 mm, or angulation ≥ 15° was considered poor. At the last follow-up, American Orthopaedic Foot & Ankle Society (AOFAS) scores were obtained, and bilateral ankle and subtalar joint flexion and extension range of motion were examined. Lateral and axial calcaneus x-ray and CT were performed to observe fracture healing and the presence of traumatic arthritis. Traumatic arthritis can be considered when there is joint space narrowing, periarticular bone hyperplasia, or subarticular bone cyst formation.
All data were analyzed using SPSS (Statistical Product and Service Solutions, USA) 26.0. Patient age, operation time, AOFAS score, and other numerical variables were analyzed using descriptive statistics. An independent sample t-test was used to compare the mean range of flexion and extension motion of the bilateral ankle and subtalar muscles. Analysis of variance was used for x-ray and CT follow-up data of the calcaneus, the least significant difference test was used for analysis between different time points, and Tamhane’s T2 was used to analyze data that did not meet the homogeneity of variance test. P < 0.05 was considered statistically significant.