The clinical data of ASD patients who underwent ACR via a minimally invasive hybird approach in the Second Affiliated Hospital of Dalian Medical University from January 2018 to June 2021 were retrospectively collected and analyzed. This study was approved by the Ethics Review Committee of the Second Affiliated Hospital of Dalian Medical University and obtained the unique identification number of research registration. This study met guidelines of the responsible local governing agency and complied with the principles of the Declaration of Helsinki. Each patient signed a written informed consent form.
Inclusion and exclusion criteria
The inclusion criteria include: ① Patients with clinically diagnosed adult spinal deformity. ② Radiographic assessment: SVA>5 cm, PI-LL mismatch>10 ◦, PT>25 º, TK>60 º,Coronal Cobb angle>20º;③ACR via a minimally invasive hybrid approach was performed.
The exclusion criteria include: ①Lack of information including demographics, surgical data, radiographic data. ②Adolescent idiopathic scoliosis patients who developed later in adulthood. ③ Trauma, inflammation, tumor or neuromuscular origin; ④Severely rigid spinal sagittal imbalance (SVA>20cm or PI-LL>40 °); ⑤with previous lumbar surgery.
A total of 64 patients were enrolled after applying the inclusion and exclusion criteria.
Data collection
The patient's clinical and radiological information is obtained by accessing the electronic record system. The standard demographics, including age, sex. Several variables pertinent to the operative data were recorded for each patient, including operative time, estimated blood loss (EBL), method for interbody fusion. The imaging data mainly includes: pelvic incidence (PI), lumbar lordosis (LL), Intervertebral space angle of the surgical segment (IVA);sagittal vertical axis (SVA). Intraoperative or postoperative complications were recorded.
At 1, 3, and 6 months postoperative follow-up, frontal and lateral radiographs of the lumbar spine were obtained to measure IVA, lumber lordosis, and sagittal vertebral axis respectively. CT examinations were performed at 3 months postoperatively to assess fusion and internal fixation stability. Pre-operative and post-operative follow-ups were performed using the visual analog scale (VAS) and lumbar JOA score to assess the clinical outcome.
Surgical technique
The anterior longitudinal ligament(ALL) can enhance the stability of the spine and as a barrier to prevent anterior dislodgement of the interbody cage. However, concerning sagittal deformity correction, ALL is also the main obstacle to against anterior column lengthening and deformity correction. Therefore, ACR technology includes the release of ALL and lateral ligament complex, and the placement and fixation of a hyperlordotic cage to correct focal kyphosis.
In the pre-operative stage of the procedure, the patient was placed in the standard lateral position in the same manner as for a lateral lumbar interbody fusion. Use the retroperitoneal approach to access the intervertebral disc space, and then the retractor is placed to expose the intervertebral disc in front of the posterior retractor blade. Gentle dissection is performed to identify and separate the plane between ALL and the anterior structure. Two-thirds of all anterior intervertebral discs must be removed to facilitate ALL release. Release the anterior longitudinal ligament and anterior vascular structure, a narrow abdominal retractor is inserted between them, and then release ALL with a long-handled scalpel. Use a reamer to break through and disconnect the contralateral remaining annulus. After that, sequential implant trialing and insertion are then performed using standard techniques.
Considering that ALL release will make the fusion cage move forward, it is very important to Internal fixation the implants to the vertebral body with 1 or 2 screws to reduce the risk of implant movement. When posterior pressure release and additional lordosis are generated, fixing the cage to only 1 vertebral body is recommended. For the high iliac crest, L5/S1 segment cannot be performed at the same incision. Usually, the anterior approach is via the abdominal or retroperitoneal approach. Posterior routine percutaneous screw fixation, and screw compression if necessary to obtain additional lordosis correction.
Perioperative management
On the first or second day after the operation, lumbar spine x-rays was repeated with the duration postoperative activity determined by the patient's status. Most patients were able to walk after surgery day 1-3, protected by a lumbar brace. Methylprednisolone, omeprazole, parecoxib, and rivaroxaban were used for conventional treatment 3 days after operation.
Data analysis
The SPSS 25.0 software was used to analyze the data. The statistical results were described, with continuous variables shown as means and standard deviations, and classification shown as a percentage. To compare the differences between pre-and post-operative related parameters, the Paired samples t-test has been used. P < 0.05 was regarded as statistically significant.