We retrospectively studied all of the patients admitted to our hospital for the repair of intra-articular calcaneal fractures between July 2016 and September 2018. All methods were carried out in accordance with relevant guidelines and regulations. The ethics committee of the Second Affiliated Hospital of Soochow University reviewed and approved this study. Informed consent was obtained from all subjects. The inclusion criteria were as follows: ① patient between 20 and 70 years old, ② patient with closed intra-articular calcaneal fractures classified as Sander’s type II~IV, ③ all patients received ORIF via the MSTA or ELA, ④ patient had no major medical comorbidities, such as severe hypertension, diabetes, cancer, history of myocardial infarction or stroke, ⑤ patient was followed up for at least 12 months. The exclusion criteria were as follows: ① patient suffered extra-articular or open calcaneal fractures, ② other fresh fractures or neuromuscular injuries existed on the affected side of foot, ③ patient had rheumatoid arthritis or osteoarthritis, severe osteoporosis, severe peripheral vascular disease, and a history of calcaneal fractures. ④ patient was followed up for less than 12 months.
A total of 108 patients (117 feet) met these inclusion criteria and were included for analysis. Fifty-two patients (56 feet) who were treated by the modified sinus tarsal approach were assigned to the MSTA group and 56 patients (61 feet) who were treated by the extensile lateral approach were assigned to the ELA group. All operations were performed by the same surgeon (Jiang Bo), and all of the patients were required to cease alcohol consumption and smoking after the calcaneal fractures.
There were 39 males (75.00%) and 13 females (25.00%) in the MSTA group, and their average age was 41.69±10.57 years. According to the Sander’s classification, there were 19 feet that were type II, 31 feet that were type Ⅲ, and 6 feet that were type Ⅳ. The time that had elapsed between injury and surgical intervention ranged from 2 to 8 days with an average of 4.11±1.27 days. The total length of the hospital stay for patients was 8.23±1.73 days. There were 43 males (76.79%) and 13 females (23.21%) in the ELA group and their average age was 44.95±10.62 years. According to the Sander’s classification, there were 19 feet that were type II, 37 feet that were type Ⅲ, and 5 feet that were type Ⅳ. The time that had elapsed between injury and surgical intervention ranged from 5 to 12 days with an average of 7.05±1.45 days. The total length of the hospital stay for patients was 12.66±2.26 days. Additional demographic data were collected for both groups, including the injured side and the mechanism of injury (Table 1).
Modified Sinus tarsi approach
General anaesthesia or spinal anaesthesia was administered in all of the patients. While under anaesthesia, the patient was placed in the lateral position with the affected side on the upper side, and a pneumatic tourniquet was applied to the thigh of affected side. The prone position was used if the patient had a bilateral calcaneal fracture. An incision was made from the tip of the lateral malleolus to the point of the anterior calcaneal process. The direction of the incision was parallel to the plane of the plantar (Fig. 1). The main sural nerve was located in the area below the incision and did not need to be exposed during the dissection. The skin, subcutaneous tissue, and inferior extensor retinaculum were cut along the skin incision to expose the peroneal tendon sheath which was pulled downward. It was important to maintain the integrity of the tendon sheath and surrounding subcutaneous tissue. The extensor digitorum brevis terminal tendon was carefully stripped off and the sinus tarsi was exposed. The subtalar joint capsule was cut open to explore the posterior articular surface of the calcaneus, and the haematoma and adipose tissue were cleaned. The lateral calcaneal wall was stripped by sharp dissection through the sinus tarsi incision and the calcaneus ligament was cut off. Then, it was possible to expose and further reduce the collapsed posterior articular surface of the calcaneus using a periosteum stripper (Fig. 2a). A Kirschner wire was drilled below the articular surface along the direction of the sustentaculum tali for temporary fixation. A percutaneous Steinmann pin was drilled into the calcaneal tuberosity, which was used to reduce the varus deformity of the calcaneus and the comminuted lateral wall. The percutaneous Kirschner wires were then drilled along the long axis of the calcaneus for temporary fixation. Next, the lateral and axial positions of the calcaneus were observed by C-arm fluoroscopy to ensure that the length, width, and height of the calcaneus, the posterior articular surface, the Bohler Angle and the Gissane Angle were satisfactorily restored. Finally, a locking plate was inserted and placed on the lateral side of the calcaneus through the modified sinus tarsi incision (Fig. 2b). Several small incisions were made on the lateral calcaneal skin according to the location of the screw holes, through which the screws were inserted (Fig. 2c,2d). In this group, no ligamentum calcaneus was repaired, and no bone grafting was performed on the bone defect. The incision was sutured after placing a negative pressure drainage ball or drainage strip. The affected limb was fixed with plaster or braces for 2-3 weeks after the operation, and postoperative weight-bearing began at the eighth week.
Extensile lateral approach
In this group, the standard ELA was used for reduction and fixation of the calcaneal fractures. First, a smooth L-shaped incision was made from between the lateral malleolus and the Achilles tendon to the bottom of the fifth metatarsal (Fig. 3a). The full-thickness flap which contained the sural nerve and peroneal tendons was separated at the periosteum level and fixed temporarily with three Kirschner wires. Next, the collapsed articular surface was pried up and the articular fragments were fixed with Kirschner wires. The calcaneus was restored to its normal shape by extruding and pulling. After the length, width, and height of calcaneus, the posterior articular surface, the Bohler Angle and the Gissane Angle were satisfactorily restored, a calcaneal locking plate was used for fixation (Fig. 3b). Postoperative management was the same as in the MSTA group described above.
Functional and radiological evaluation
All patients underwent pre- and postoperative clinical and radiological evaluations. The results of the clinical evaluation were obtained from the American Orthopaedic Foot and Ankle Society (AOFAS) and included hindfoot score, the visual analogue scale (VAS), and the Short Form-36 Health Survey (SF-36) questionnaire. At the same time, we collected the postoperative complications experienced by all of the patients. The AOFAS score assigns 100 points to normal hindfoot and ankle joints, including pain (50 points), function (40 points) and alignment (10 points). We set a score of 90-100 as excellent, 75-89 as good, 50-74 as medium, and below 50 as poor. The VAS, which ranges from 0 (no pain) to 10 (extreme pain, seriously affects work and life), was used to measure the amount of pain. The SF-36 is a questionnaire that contains 36 items grouped into eight domains as follows: physical function, role physical, bodily pain, general health, vitality, social function, role emotional and mental health. Based on all of the items, a physical component summary (PCS) and a mental component summary (MCS) of health can be calculated. The SF-36-PCS comprises PF, RP, BP and GH. The SF-36-MCS comprises VT, SF, RE and MH.
Radiological assessment indicators include the following aspects. Preoperative lateral and axial X-ray imaging and a CT scan were performed on the damaged calcaneus to evaluate the condition and classify the fractures. Lateral and axial X-ray radiographs of the damaged calcaneus were performed at 4 weeks, 3 months and 12 months after the operation. Then, the preoperative and postoperative changes of the Bohler Angle, Gissane Angle, calcaneal length, calcaneal width, and calcaneal height were calculated based on the X-ray imaging and CT scan results (Fig. 4,5). Meanwhile, the healing of the calcaneal fractures and the incidence of complications were evaluated.
Statistical analyses were performed using SPSS software (version 20.0). In this study, continuous variables were expressed as the means±standard deviations (SDs) and categorical variables were expressed as numbers (N) and percentages (%). The independent sample t-test and ANOVA were employed to compare differences between the two groups. A paired Student’s t-test was performed to compare differences within the same group, and categorical variables were compared by a chi-square test. P values < 0.05 were considered statistically significant.