This retrospective study consists of 58 patients with tibial shaft fractures, who were admitted to our department and consented to hexapod external fixator (Tianjin Xinzhong Medical Instrument Co., Ltd., Tianjin, China) treatment from January 2015 to April 2019. Inclusion criteria were open fractures and closed fractures with poor surrounding soft tissues. Patients with pathological fractures, age > 65, poor compliance, and patients treated initially with the HEF but converted to internal fixation were excluded. Informed consent was obtained from all patients for their data to be documented and published in our study. The Ethical Committee of our institution approved this study.
Twenty-three patients (Group Ⅰ) underwent intraoperative acute correction, from January 2015 to October 2016. There were 20 males and 3 females with an average age of 39 years (range 19 to 64 years), including 13 left extremities and 10 right extremities. This group included 15 open fractures and 8 closed fractures. The fractures were divided by the OTA classification system. The injury mechanism was road traffic accident in 17 patients, fall from height in 4 patients, and crushing injury in 2 patients. The mean time elapsed since the injury to the HEF installed was 3.9 days (range 1 to 8 days). The physiological instability and associated soft-tissue injury contributed to the delayed installation of the HEF.
Starting in November 2016, the other 35 patients (Group Ⅱ) all underwent postoperative gradual correction. This group consists of 27 males and 8 females with a mean age of 41 years (range 26 to 61 years), containing 21 left extremities and 14 right extremities. There were 24 open fractures and 11 closed fractures. The injury mechanism was road traffic accident in 25 patients, fall from height in 7 patients, and crushing injury in 3 patients. The mean time elapsed since the injury to the HEF installed was 3.2 days (range 1 to 9 days).
The same medical team performed all the surgical procedures. The demographic data, operation duration, original residual deformities before correction, residual deformities after correction, and external fixation time were collected and analyzed. The intraoperative and perioperative difficulties were subclassified according to Paley11. The clinical outcomes were evaluated by the Johner-Wruhs criteria12 at the last clinical visit.
The Technique Of Deformity Correction
For intraoperative acute correction, the HEF was installed using a method similar to Gantsoudes et al.13. The reference ring must be mounted vertically to the long axis of the proximal bony fragment. The deformity parameters were measured using intraoperative fluoroscopy. For mounting parameters, one nut was placed firstly at the midpoints of the anteroposterior (AP) view on the reference ring. Subsequently, the anterior marker (a rod with a cube) was placed at the center hole of the master tab (anterior tab) on the reference ring. With the injured limb is slowly rotated, projections of these two markers were overlapped under static or live fluoroscopy, and the distance of the rod (representing the center of the ring) to the center of the tibia was measured with a sterile ruler directly off of the cube. The AP view frame offset and lateral view frame offset were measured by the method mentioned above. The axial view frame offset was calculated by the distance from the reference ring to the origin point. All the parameters were entered in the computer program, and the residual deformities were corrected acutely depending on the electronic prescription.
As for postoperative gradual correction, the “ring-first” technique was used in all the patients. The reference ring was perpendicular to the long axis of the corresponding bony segment in an orthogonal manner. Standard postoperative orthogonal AP and lateral radiographs were used to evaluate the residual deformities and calculate the mounting parameters. The AP view frame offset was measured using the distance of the line perpendicular to the anatomical axis of the reference bony fragment from the center of the reference ring to the origin point. The lateral view frame offset was calculated in the same way. The axial view frame offset was calculated using the distance of the line parallel to the anatomical axis of the reference bony fragment from the center of the reference ring to the origin point. All the residual deformities were corrected by gradual strut adjustment postoperatively within seven days, according to the electronic prescription.
The translation and angulation in the coronal and sagittal plane, according to the standard AP and lateral X-rays after correction, was used to evaluate the effectiveness. Isometric muscle and joint range of motion exercises were recommended for all patients on the second day after the operation. The foot was kept in a neutral position to prevent ankle equines contractures using a rigid shoe with an elastic band. Daily pin site care with alcoholic chlorhexidine was performed to avoid pin tract infection.
The patients were followed up and taken a radiograph monthly until the bone union was achieved. The HEF was removed when sufficient union (corticalization in 3 of 4 cortices) was shown in radiographs. The functional brace was used to prevent refracture for four weeks after frame removal in all patients.
Statistical analysis was performed with the SPSS 22.0 (IBM Corp, USA). Continuous variables were analyzed by Independent-samples T-tests and expressed as the mean, standard deviation, and range of the observations. And the count variables were analyzed by the Chi-square or Fisher’s test, expressing as a number. A statistically significant difference was set at P < 0.05.