[Role of intercellular adhesion molecule-1 in adhesion and migration of mesenchymal stem cells in ankylosing spondylitis and its mechanisms].

Objective: To investigate the role and underlying mechanisms of intercellular adhesion molecule-1 (ICAM-1) in the adhesion and migration of mesenchymal stem cells (MSCs) in patients with ankylosing spondylitis (AS). Methods: Bone marrow and ligament tissues were collected during surgery from patients with AS and thoracolumbar fractures (as controls, HC) treated from October 2021 to October 2022 at Nanjing University Medical School Affiliated Nanjing Drum Tower Hospital. MSCs were isolated and cultured from the bone marrow using the Ficoll separation method. Cell morphology was observed under high-resolution microscopy, and differences in the cytoskeletal features between AS-and HC-MSCs were analyzed through immunofluorescence staining. The expression of ICAM-1 was quantified in both groups using real-time quantitative polymerase chain reaction (RT-qPCR) and flow cytometry. Transwell migration assays and wound healing experiments were conducted to evaluate the differences in migration rates between the two groups of MSCs. Results: The interspinous ligament and bone marrow was acquired in AS (2 males and 1 female; 33, 37, 32 years old, respectively) and no-AS patients (2 males and 1 female; 35, 32, 38 years old, respectively). AS-MSCs exhibited broader cell morphology compared to HC-MSCs under bright field and fluorescence microscopy. Immunofluorescence staining of the interspinous ligament showed higher expression of ICAM-1 (68.38±3.42 vs 48.31±2.43) and CD105 (37.97±2.16 vs 23.36±2.06) in AS patients (both P<0.001). Western blot and RT-qPCR analysis revealed significantly stronger protein expression and transcription levels of ICAM-1 in AS-MSCs when compared to those in HC-MSCs (both P<0.001). Flow cytometry confirmed greater mean fluorescence intensity of ICAM-1 in AS-MSCs than in that in HC-MSCs (924.30±54.99 vs 636.47±40.03, P=0.002). Regarding cell adhesion efficiency, it showed no significant difference between AS-MSCs and HC-MSCs in the early stage of adhesion (0.5 h: 1 496±213 vs 1 205±163, P=0.133), but they were all significantly higher in AS-MSCs in the later stage (1 h: 2 894±172 vs 1 908±155, P=0.002; 2 h: 4 540±286 vs 3 334±188, P=0.004; 3 h: 5 212±281 vs 4 208±303, P=0.014). Finally, cell migration experiments demonstrated a stronger migration capability of AS-MSCs compared to HC-MSCs (5 449±172 vs 4 016±155, P<0.001), and the inhibition efficiency of A-205804 on the migration rate of AS-MSCs was stronger than that on HC-MSCs (2 145±239 vs 3 539±316, P=0.004). Conclusions: The aberrant expression of ICAM-1 markedly influences the adhesion and migration dynamics of MSCs. Elevated ICAM-1 levels in MSCs derives from patients with AS significantly enhance their migratory capabilities.

[Clinical application of minimally invasive lumbar interbody fusion].

With the popularization of minimally invasive concept in the treatment of lumbar degenerative disease,minimally invasive lumbar interbody fusion has gradually developed into the mainstream technique of lumbar fixation and fusion.At present,there are many types of minimally invasive lumbar interbody fusion. In this paper, four kinds of minimally invasive lumbar interbody fusion (anterior lumbar interbody fusion,minimally invasive transforaminal lumbar interbody fusion,extreme lateral interbody fusion,oblique lumbar interbody fusion),which are widely used in clinical practice,are systematically described from the aspects of indication selection,technical characteristics, clinical efficacy and prevention of complications.In order to obtain the best treatment effect with the least trauma,it is necessary for the surgeons to formulate detailed surgical strategies on the basis of strictly grasping the indications,and choose the operation according to their own clinical experience and skills,so as to maximize the advantages of different minimally invasive lumbar interbody fusion.

[Occurrence of rod fracture and salvage methods after primary surgery of the congenital lumbosacral deformity associated with sacral agenesis].

Objective: To analyze the occurrence of rod fracture after surgery for lumbosacral deformity associated sacral agenesis and discuss the relevant salvage methods. Methods: The clinical records of 19 patients who underwent surgical treatment for lumbosacral deformity associated sacral agenesis from January 2001 to January 2018 were retrospectively reviewed, including 11 boys and 8 girls. The average age was (9.6±5.2) years. The outcomes of surgical correction and internal fixation were evaluated by postoperative regular follow-up. We also recorded the time and position of rod fracture occurrence. The Cobb angle, coronal balance and sagittal balance were measured and compared to analyze the corresponding salvage methods and revision outcomes. Results: Three patients encountered rod fracture during follow-up, so the incidence of rod fracture after surgery for lumbosacral deformity associated sacral agenesis was 15.8%(3/19). Based on their own conditions, we formulated the individualized strategy and performed the revision surgery through the posterior-only approach. The most critical step was abundant bone-grafting and fusion in the defected sacroiliac joint. After revision, the scoliotic Cobb angle improved in two patients (91.5° vs 47.5°, 49.0° vs 28.0°) and coronal balance improved in one patient (40.3 mm vs 24.3 mm). No complication reoccurred during follow-up. Conclusion: The rod fracture after surgery for lumbosacral deformity associated sacral agenesis is quite common, which is probably correlated with its unique deformed structure and biomechanical characteristics. The individualized salvage methods and adequate bone-grafting and fusion for the defected sacroiliac joint will guarantee the reconstruction and maintenance of spine balance after revision.

[Comparison of clinical outcomes between type B and type C coronal pattern patients with degenerative scoliosis].

Objective: To investigate the differences of the radiographic and clinical outcomes after posterior correction surgeries between degenerative scoliosis (DS) patients with type B and type C coronal pattern. Methods: From March 2010 to August 2017, the clinical data of 38 patients (type B: 24; type C: 14) who were treated with posterior correction surgeries for DS were retrospectively reviewed. Radiographic parameters including Cobb angle of main curve, coronal imbalance (CI), lumbar lordosis (LL), global kyphosis (GK) and sagittal vertical axis (SVA) were measured on standing anteroposterior and lateral radiographs of the whole spine before and after surgery. Patient-reported outcomes were evaluated by using the visual analogue scale (VAS), the Oswestry disability index (ODI) and SF-36 questionnaire. The independent t-test was applied to compare the difference for statistical analysis. Results: There was no significant differences between the two groups in terms of age, gender, follow-up duration, preoperative curve magnitude, severity of CI, sagittal malalignment and surgical strategies (all P>0.05). In patients with type B coronal pattern, the main curve was corrected from 44°±19° before surgery to 19°±7° immediately after surgery (t=8.496, P<0.001) and to 19°±6° at the last follow-up (t=-0.657, P=0.518). In patients with type C coronal pattern, the main curve was corrected from 43°±9° before surgery to 21°±4° immediately after surgery (t=13.537, P<0.001) and to 21°±5° at the last follow-up (t=-0.186, P=0.856). No significant difference of Cobb angle of main curve was found between the two groups either before the operation or immediately post operation (all P>0.05). In addition, significant improvement of CI was observed after surgery in both groups and the correction was maintained well at the last follow-up. However, patients with type C coronal pattern had greater CI than that in those with type B coronal pattern immediately post operation (t=-2.401, P=0.022) and at the last follow-up (t=-2.659, P=0.012). At the last follow-up the scores of SF-36 questionnaire, ODI and VAS showed significant improvement in both groups (all P<0.05). Conclusion: Posterior correction surgery could provide remarkable radiographic and clinical outcomes in DS patients with type B and type C coronal pattern, and DS patients with type B coronal pattern could achieve a more satisfied coronal balance after surgery.

[Comparison of hybrid and traditional growing rod techniques in the treatment of early-onset congenital scoliosis].

Objective: To compare the surgical outcomes between hybrid and traditional growing rod (GR) techniques in the treatment of early-onset congenital scoliosis (C-EOS). Methods: A review was conducted of C-EOS patients who had undergone hybrid GR treatment at Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School. Another group of patients who had undergone traditional GR were well matched to the hybrid GR group at a 1∶1 ratio in terms of main Cobb angle, age at initial surgery, and lengthening numbers. There were 5 boys and 8 girls with an age of (5.6±2.8) years in the hybrid GR group, and 6 boys and 8 girls with an age of (6.1±3.0) years in the traditional GR group, respectively. All patients had minimum 2-year follow-up and over 2 lengthening procedures. Radiographic data were compared with paired t tests in either group between each visit, and with independent t tests between the two groups. Results: On average, the hybrid group had a follow-up of (42.2±13.4) months (range:27-81 months), and had (4.0±1.8) lengthening procedures with a lengthening interval of (10.5±1.0) months; and the traditional GR group had a follow-up of (45.4±15.2) months (range: 24-76 months), and experienced (4.2±1.9) lengthenings with an interval of (10.8±1.1) months. After the index surgery, the major Cobb angle, C(7) translation, apical vertebral translation, and thoracic kyphosis (TK) had remarkable improvement in both groups. Notably, the hybrid GR group had significantly higher correction rates of major Cobb angle (t=2.348, P=0.027) and TK (t=3.768, P<0.001) than the traditional GR group. At the latest follow-up, the hybrid GR group had remarkably smaller Cobb angle of the major curve than the traditional GR group (t=2.790, P=0.010). At the same time, the hybrid GR group had higher T(1)-S(1) height gain than the traditional GR group (t=2.846, P=0.008) after the index surgery. Whereas, non-significant difference was noted between two groups with regards to the T(1)-S(1) growth rate during follow-up (t=0.516, P=0.610). Ten complications occurred during the follow-up period, including 2 in the hybrid GR group and 8 in the traditional GR group. The incidence of rod breakage and PJK in the traditional group was 3 and 4 times as high as that of the hybrid GR group, respectively. Conclusions: The hybrid growing rod can not only help to improve the correction of spinal deformity but also decrease postoperative complications during follow-up. Moreover, apical short fusion shows no significant influence on spinal growth.

[Comparison of spontaneous correction in thoracic curves after anterior versus posterior selective fusion in Lenke type 5C adolescent idiopathic scoliosis].

Objective: To analyze the long-term results and the influence factors of spontaneous correction of unfused thoracic curves in anterior and posterior selective fusions in Lenke type 5C adolescent idiopathic scoliosis (AIS). Methods: From January 2005 to December 2011, 89 Lenke type 5C AIS patients with a minimum of 5-year follow-up who underwent thoracolumbar/lumbar (TL/L) selective fusion in Spine Surgery of Nanjing Drum Tower Hospital were reviewed.Forty-six patients underwent anterior fusion (anterior group), while 46 underwent posterior fusion (posterior group). The following radiological parameters were measured and analyzed at pre-operation, post-operation, and latest follow-up: curve magnitude of primary thoracolumbar/lumbar and secondary thoracic curve, trunk shift, thoracic apical vertebral translation, upper instrumented vertebra tilt, thoracic kyphosis, proximal junctional angle, sagittal vertical axis. Independent sample t test was used to compare the above parameters between the two groups. Results: Compared with those in posterior group, anterior group were found with less fusion levels (5.4±0.6 vs 5.9±0.8, t=3.318, P=0.001) and longer operation time[(276±28)min vs (186±36)min, t=13.101, P<0.001]. Immediately after surgery, the spinal deformity was significantly corrected in the two groups. The mean spontaneous correction rates of the minor curve were 50%±21% and 56%±20% in anterior and posterior groups, respectively (t=1.489, P=0.140). After a mean follow-up of (6.8±1.7) years in anterior group and (6.3±1.3) years in posterior group, the spontaneous correction rate of minor curve was maintained at 46%±22% and 49%±19%, respectively (t=0.703, P=0.484), with no significant correction loss. Other radiographic parameters were also stably maintained. According to the correlation analysis, the spontaneous correction rate was significantly correlated with upper instrumented vertebra (UIV) tilt in both groups (anterior: r=-0.526, posterior: r=-0.399, both P<0.05). Conclusions: Both anterior and posterior selective fusion can achieve satisfactory spontaneous correction of unfused thoracic curves in Lenke type 5C AIS, with no significant difference between the two surgical approaches. UIV tilt is a key influence factor of spontaneous correction of thoracic curves.

[Similar coronal curvature may not represent the same 3-dimensional deformity in adolescent idiopathic scoliosis: a matched-pair study using EOS imaging system].

Objective: To analyze the preoperative axial plane and the surgical outcomes of the Lenke type 1A patients with adolescent idiopathic scoliosis (AIS) whose coronal curve type was matched but thoracic kyphosis (TK) was different. Methods: This study retrospectively reviewed a series of Lenke type 1A female AIS patients who underwent corrective surgery in the Department of Spine Surgery of Nanjing Drum Tower Hospital from May to August 2017. After matched with the Cobb angle of the main thoracic curve, the apical vertebral, the vertebra number included in the curve, the lumber modifier in the Lenke classification and Risser sign, 12 pairs of AIS patients, whose coronal curve was matched but thoracic kyphosis was different, were included in this study. The patients were divided into normal TK group and thoracic hypokyphosis group. EOS whole-body images were taken preoperatively and reconstructed by three-dimensional reconstruction. The whole spine anteroposterior X-ray was taken at 3 weeks after surgery. The radiographic parameters were measured on the preoperative and postoperative two-dimensional X-ray images: coronal Cobb angle, TK, lumbar lordosis (LL), pelvic incidence (PI) and pelvic tilt (PT). The vertebra rotation was obtained on the EOS three-dimensional reconstructed image, and the average vertebral rotation of the major thoracic curve (MTR), the average vertebral rotation of the proximal thoracic curve (PTR) and the average vertebral rotation of the lumbar curve (LR) were calculated. The paired sample t test was used to compare the difference of preoperative and postoperative radiographic parameters between the groups. Results: A total of 24 patients (12 pairs) were included in this study with an average age of (13.7±2.9) years. The preoperative Cobb angle was similar in the two groups (53.8°±10.2° vs 51.0°±11.1°, t=0.27, P=0.81). The average preoperative TK of the normal TK groups was 28.2°±6.1°, while that of the thoracic hypokyphosis group was 11.2°±5.6°(t=7.68, P<0.01). The MTR in the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (10.2° vs 12.7°, t=-3.74, P<0.01), and there was a significant correlation between TK and MTR (r=0.30, P=0.03). As for the lumbar curve rotation, the LR of the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (t=-2.65, P=0.002), but the absolute value of the two groups was similar (t=-0.33, P=0.31). The lumbar Cobb angle correction rate was significantly greater in patients with thoracic and lumbar curve rotating in the same direction than that in the opposite direction (81.1% vs 61.9%, t=4.24, P=0.005). Conclusions: It indicated that when the coronal deformity is matched, the MTR of the patients with thoracic hypokyphosis is significantly larger than that in the patients with normal thoracic kyphosis. The direction of the thoracic and lumbar curve rotation is required to be well concerned in the preoperative surgical planning.

[Effects of Scoliosis Research Society-Schwab grade â £ osteotomy for post-traumatic thoracolumbar kyphosis].

Objective: To evaluate the effectiveness of Scoliosis Research Society (SRS)-Schwab grade Ⅳ osteotomy in the treatment of post-traumatic thoracolumbar kyphosis (PTK). Methods: From October 2012 to January 2015, a total of 31 patients [12 males, 19 females, mean age (43±10) years] with symptomatic PTK undergoing SRS-Schwab grade Ⅳ osteotomy in Nanjing Drum Tower Hospital were retrospectively reviewed.Radiographic changes were evaluated with preoperative, postoperative and follow-up X-ray.The measurements included thoracic kyphosis (TK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), focal kyphosis (FK), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and sagittal vertical axis (SVA). Clinical outcome was assessed using the visual analogue scale (VAS), the Oswestry disability index (ODI) and Frankel neurological grade before surgery and during follow-up.The preoperative, postoperative and follow-up data were compared with paired t test. Results: All patients were followed-up for 28±5 months (24-38 months). The TK and LL improved significantly postoperatively from 15.6°±7.8° and 67.3°±12.2° to 28.1°±6.2° and 48.1°±9.3°(t=-6.985, 6.968, both P<0.05), and maintained at 27.3°±6.9° and 49.4°±7.9° at last follow-up, respectively.The TLK and FK improved significantly postoperatively from 29.4°±12.2° and 36.4°±9.5° to 7.7°±5.3° and 5.6°±4.2°(t=9.083, 16.510, both P<0.05), with a correction loss of 2.4°±2.0° and 2.3°±2.2° at final follow-up, respectively.No significant difference was observed in the PI, PT, SS and SVA among preoperative, post-operative and the last follow-up data.In addition, the VAS and ODI improved significantly at the final follow-up.Four cases with Frankel D experienced complete neurological recovery at the final follow-up.Radiographic evaluation showed solid bony fusion.No instrument-related complication was observed during the follow up. Conclusions: The SRS-Schwab grade Ⅳ osteotomy brings satisfactory sagittal alignment and good clinical outcomes in patients with PTK.

[Outcome of traditional growing rods for correction of apical vertebra rotation in early-onset scoliosis].

Objective: To evaluate the correction result of traditional dual growing rods on apical vertebral rotation. Methods: This study recruited 19 early-onset scoliosis patients (6 boys and 13 girls) who had received traditional dual growing rods treatment at Department of Spine Surgery, Nanjing Drum Tower Hospital from January 2009 to July 2015. The age at initial surgery was (5.7±1.7)years(range, 3 to 9 years). Measurements of primary curve magnitude, height of T(1)-S(1), apical vertebral translation(AVR), apical vertebral body-rib ratio, apical vertebral rotation, thoracic rotation and rib hump were compared between pre-operatively, post-operatively, and at latest follow-up, through a paired-t test. Pearson correlation test was used for correlation analysis between parameters. Results: All patients had a follow-up of (49.5±12.8)months(range, 24 to 71 months). A total of 111 operative procedures were performed, among which there were 92 lengthening procedures, averagely 4.8 lengthening procedures per patient. The average interval for each lengthening procedure was 10 months. The Cobb angle of primary curve was notably decreased from (66.5±13.2)° to (35.2±10.9)°(t=24.013, P<0.01), and no significant correction loss was found at the latest follow-up ((36.7±10.7)°)(t=-1.324, P=0.202). In addition, significant correction of AVR, thoracic rotation, apical vertebral translation, apical vertebra body-rib ratio, and rib hump were noted after initial surgery. Whereas, these parameters significant increased during follow-up(all P <0.05) except for thoracic rotation. Pearson correlation analysis showed that the increase of AVR during follow-up significantly correlated with change of apical vertebra translation, apical vertebral body-rib ratio, and rib hump(r=0.652, 0.814, 0.695; all P<0.05). Conclusions: Significant correction of AVR can be achieved after initial surgery in early-onset scoliosis patients treated with traditional dual growing rods. However, such a technique can hardly prevent the deterioration of AVR during follow-up.

[Comparison of clinical outcome between utilized second sacral alar-iliac and iliac screw on kyphoscoliosis patients].

Objective: To compare the clinical outcome and health related quality of life(HRQoL)of patients with degenerative spinal deformity who underwent spino-pelvic fixation utilized second sacral alar-iliac(S(2)AI)with patient utilized traditional iliac screw(IS). Methods: Patients diagnosed as degenerative spinal deformity who underwent spino-pelvic fixation utilized either S(2)AI screw or Iliac screw at Department of Spine Surgery of Drum Tower hospital from January 2013 to January 2016 were retrospectively analyzed. Patients were divided into two groups according to the pelvic fixation technique. Cobb's angle, coronal balance distance(CBD), regional kyphosis(RK), sagittal vertical axis(SVA)were recorded at pre-operation, post-operation and last follow up. The MOS item short from the health survey(SF-36), visual analogue scale(VAS), Oswestry disability index(ODI) were also recorded at pre-operation and last follow up. Five physical examinations were administered to all patient at the last follow up to diagnose sacroiliac joint dysfunction, three tests resulting positive were regarded as dysfunction. Repeated measurement analysis of variance, t-test or non-parametric test was used to analyzed the data, respectively. Results: A total of 22 patients who met the inclusion were recruited in this study. Fourteen patients were utilized S(2)AI screw and 8 patients were utilized iliac screw.There were no significant differences in age, gender, follow up time between two groups. Cobb's angle, CBD, RK, SVA at pre- and post-operation and last follow up showed no significant difference between two groups.SF-36, ODI, VAS at pre-operation and last follow up showed no significant difference between two groups. Compared with baseline, Cobb's angle(44.4°±14.0° vs. 20.2°±7.2° vs. 18.3°±7.1°), C(7)PL-CSVL((25.3±16.0)mm vs. (10.3±5.7)mm vs. (9.2±4.2)mm), RK(33.0°(-12.0°, 50.0°) vs. 20.0°(-33.0°, 8.5°) vs. -19.0°(-29.0°, 19.0°)), SVA((31.5±34.4)mm vs. (12.1±8.4)mm vs. (10.9±7.2)mm), SF36-physical function summary(PCS)(39.8±14.3 vs. 68.2±21.5), SF36-mental component summary(MCS)(44.9±14.8 vs. 73.9±19.9), ODI(37.7±16.9 vs. 19.8±15.8), VAS(4.8±2.1 vs. 1.8±0.9) were significantly improved postoperatively in S(2)AI group(P<0.05). In the IS group, compared with baseline, Cobb's angle(54.3°±18.3° vs. 26.1°±13.2° vs. 25.6°±18.3°), C(7)PL-CSVL((31.0±16.0)mm vs. (13.9±7.0)mm vs. (12.4±6.6)mm), RK (47.0°(15.0°, 57.0°) vs. 4.0°(-10.0°, 16.0°) vs. 7.0°(-9.0°, 12.0°)), SVA((27.1±23.9)mm vs.(13.1±7.5)mm vs. (13.6±6.0)mm), SF36-PCS(29.7±7.1 vs. 61.1±11.2), SF36-MCS(35.9±7.1 vs. 64.0±11.1), ODI(48.6±13.4 vs. 19.0±10.7), VAS(4.9±1.8 vs. 2.6±1.3) were also significantly improved postoperatively(all P<0.05). There were two patients need revision surgery in the IS group due to the instrumentation-related complication. None of the patients in the S(2)AI group needed revision surgery. There were no instances of sacroiliac joint dysfunction in both groups at last follow up. Conclusion: Spino-pelvic fixation utilizing S(2)AI screw could provide similar correction rate to iliac screw and the sacroiliac joint penetration due to S(2)AI won't affect the HRQoL in patient with degenerative deformity who utilized S(2)AI.

[Proximal junctional kyphosis after posterior hemivertebra resection and instrumented fusion in young children with congenital scoliosis].

Objective: To investigate the risk factors of proximal junctional kyphosis(PJK) in young children who underwent posterior hemivertebra resection and instrumented fusion. Methods: This study reviewed the charts and radiographs of 136 consecutive young children with congenital scoliosis who underwent posterior hemivertebra resection and instrumented fusion in Department of Orthopaedics, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School from January 2009 to June 2014, including 75 males and 61 females, with an average age of (5.0±1.7)years(3-10 years). Proximal junctional angle(PJA), spino-pelvic parameters and segmental kyphosis (SK) were recorded pre- and post-operation and at last follow-up.The changes of PJA and radiographic features of proximal junction were also observed.χ(2) test and t-test were used to analyzed enumeration data and measurement data, respectively. Results: The average follow-up period was (32.8±10.3)months (ranging from 24 to 73 months) by June 2016. Among these patients, PJK occurred in 19 cases. Fifteen patients developed PJK during the first 3 months after surgery.The most common type of PJK was ligamentous failure.Compared with the non-PJK group (22.2%, 37.6%, 13.7%), the PJK group showed higher rate of preoperative TK>40°(9/19), fusion levels >4 (13/19) and greater SK change > 30°(9/19)(χ(2)=7.259, 6.375, 12.368; all P<0.05), while there were no difference between the two groups in terms of preoperative PJA, lumbar lordosis, SVA and upper instrument vertebra location(all P>0.05). The average PJA increased from 7.5°±2.9° to 21.3°±4.3° at 3 months after surgery to 20.6°±3.7° at the final follow-up visit in the PJK group.At the time of the final follow-up visit, ten patients received brace treatment, with no significant progression of PJA. Conclusions: PJK might mainly occurs within 3 months postoperatively.Its prognostic factors include preoperative hyperkyphosis, over correction of kyphosis and ligamentous failure.

[A novel self-growing rod technique for early onset scoliosis: an experimental study based on a porcine scoliosis model].

OBJECTIVE: To evaluate the efficacy of a growth-guidance growing rod in an established porcine scoliosis model via the Cobb angle correction and the continued spinal growth. METHODS: Immature pigs (age: 6 weeks old, weight: 6-8 kg) were instrumented and tethered using a three separate incisions fashion.After considerable scoliosis was induced, the pigs were randomly assigned to an experiment group (EG) and a sham group (SG). In EG, the growing rod was implanted and the pigs were euthanized 8 weeks postoperatively; while in SG, the whole instrumentations were only removed and the pigs were followed up over a 8-week period.Dorsoventral (DV) X-ray radiographs were taken prior to and immediately after the growing rod implanting surgery, and at 4-week intervals to assess the Cobb angle orrection and instrumentation positioning.The continued spinal growth and the rod sliding were also assessed from the radiographs. RESULTS: Of the 16 pigs, one pig encountered infection during the inducement of the experimental scoliosis and thus was excluded from analysis.Of the remaining 15 pigs, all animals developed progressive, structural scoliosis.The 15 pigs were randomized into EG(n=10) and SG(n=5). Two pigs in EG encountered infection and were also excluded from analysis.Of the remaining 8 pigs in EG, no neurologic complications, implant failure or infection were observed.In EG, the Cobb angle of the scoliosis before the growing rod implanted was (52.1 ±14.1)° and it decreased to (25.4±15.2)° postoperatively.After 8 weeks, the Cobb angle was (20.2±11.4)°.In SG, the Cobb angle of the scoliosis after 8-week tethering period was (55.2±15.7)° and it decreased to (53.6±15.8)° after removal of the tethering.The curvature remained stable (51.2°) during the subsequent 8 weeks.During the 8-16th week, the spinal height increased 14.2 cm and radiographic analysis of the growing rod sliding revealed an average distraction of 39.8 mm in EG; while in SG, the increased spinal height was 14.9 cm.The difference of the increased spinal height between EG and SG was not significant (P=0.821). CONCLUSION: The novel growing rod system can provide substantial correction of deformity, and additionally, allow for continually spinal growth without significant growing disturbance.