Fusion rates based on type of bone graft substitute using minimally invasive scoliosis surgery for adolescent idiopathic scoliosis.

BACKGROUND: Minimally invasive scoliosis surgery (MISS) is currently introduced on novel technique for surgical treatment of adolescent idiopathic scoliosis (AIS). This study is aimed to evaluate the efficacy of facet fusion in MISS compared to posterior fusion in conventional open scoliosis surgery (COSS) and compare facet fusion rates based on three bone graft substitutes in MISS for adolescent idiopathic scoliosis (AIS). METHODS: Eighty six AIS patients who underwent scoliosis surgery were divided into two groups: the COSS group and the MISS group. COSS was performed through posterior fusion with allograft. MISS was applied via facet fusion with three bone graft substitutes. The MISS group was further divided into three subgroups based on graft substitute: Group A (allograft), Group B (demineralized bone matrix [DBM]), and group C (demineralized cancellous bone chips). Fusion rate was measured using conventional radiographs to visualize loss of correction > 10°, presence of lysis around implants, breaks in fusion mass, and abnormal mobility of the fused segment. RESULTS: The fusion rates showed no significant difference in COSS and MISS groups (p = 0.070). In the MISS group, the fusion rates were 85, 100, and 100% in groups A, B, and C, respectively, with no significant difference (p = 0.221). There were no statistical differences between groups A, B, and C in terms of correction rate, fusion rate, and SRS-22 scores (p > 0.05). CONCLUSIONS: The facet fusion in MISS showed comparable to posterior fusion in COSS with regard to radiological and clinical outcomes. Furthermore, the type of graft substitute among allograft, DBM, and demineralized cancellous bone chips did not affect facet fusion rate or clinical outcomes in MISS. Therefore, MISS showed comparable fusion rate (with no influences on the type of graft substitute) and clinical outcomes to those of COSS in the surgical treatment of AIS.

Usefulness of MRI in determining the appropriate level of cement augmentation for acute osteoporotic vertebral compression fractures.

STUDY DESIGN: This is a prospective study on consecutive patients with acute osteoporotic vertebral compression fractures (OVCFs). OBJECTIVES: To evaluate the usefulness of magnetic resonance imaging (MRI) for diagnosing appropriate acute lesions before a percutaneous cement augmentation technique. BACKGROUND: Vertebral compression fractures related to osteoporosis are very common in the elderly. Acute OVCFs are usually treated conservatively. In recent years, minimally invasive percutaneous cement augmentation techniques, vertebroplasty and kyphoplasty, have been introduced as alternative treatment options. However, the localization of acute fractures of the spine can be difficult, yet is critical in implementing these treatments. METHODS: A total of 168 patients were enrolled in this study. All participants were 50 years of age or older and were admitted via the emergency room because of acute severe back pain with suspected OVCFs with or without a history of trauma. Standard plain radiographs and a computed tomography (CT) scan of the spine were initially obtained in the emergency room. An MRI scan with short-tau inversion recovery (STIR) sequencing of the spine was performed within 3 days of hospitalization. Patients were divided into 2 groups: single group and multiple group. The single group consisted of those with a single fracture, and the multiple group consisted of those with multiple fractures of the vertebral body, as diagnosed using only standard radiographs and CT scans. We compared the level and number of fractures from the initial findings of the standard radiographs and CT scans with the MRI scan results within each group. RESULTS: The mean age of the study participants was 68.9 years. Forty-nine patients were male and 119 were female. In the single group, the concordance rate of diagnosis was 77% (97/125) and the discordance rate was 23% (28/125). In the multiple group, the discordance rate was 65% (28/43). There was a significantly higher rate of misdiagnosis in the multiple group compared with the single group (P < 0.01). CONCLUSIONS: MRI with STIR sequencing exhibited a multitude of benefits in the exact identification of acute lesions and hidden lesions. Because of the high rate of misdiagnosis using standard plain radiographs and CT scans of the spine for OVCFs, MRI with STIR sequencing should be considered before cement augmentation procedures. Moreover, in cases with multiple lesions or severe osteoporosis, the importance of MRI should be further emphasized.

3D finite element analysis of changes in stress levels and distributions for an osseointegrated implant after vertical bone loss.

PURPOSE: The effect of stress levels and distributions around the internal nonsubmerged type implants after vertical bone resorption was investigated in this study. MATERIALS AND METHODS: An HSII implant was placed in 4 cylindrical alveolar bone models with differing degrees of thread exposures. The load applied to each implant was von Mises stress and principal stress, 250 N in axial direction and 30 degrees lateral pressure. The difference in the load between the bone and the connective portion of the implant was obtained using ANSYS analysis. RESULTS: Bone loss in the cervical area of the implant was more obvious under lateral pressure. When more threads were exposed, bone level decreased and the maximum load applied on the fixture increased. CONCLUSIONS: It was concluded that higher bone level has a biomechanical advantage with respect to stress concentration.

Comparison of surgical correction rates between titanium and cobalt-chrome-alloy as rod materials in adolescent idiopathic scoliosis.

Numerous biomechanical studies comparing titanium (Ti) and cobalt-chrome-alloy (CCM) rods are described in the literature. However, there is a dearth of literature comparing the two rod materials in adolescent idiopathic scoliosis (AIS). Therefore, the purpose of this study is to compare the correction rates of Ti and CCM rods in the treatment of AIS with double major curves. We enrolled 45 patients with AIS who underwent surgery between 2009 and 2012. We divided patients into two groups, Group A (n = 29) treated with six-millimeter Ti rods and Group B (n = 16) treated with six-millimeter CCM rods. The rod-derotation maneuver was used for correction. We measured pre- and postoperative indices of coronal alignment (Cobb's angle, coronal balance, T1-tilt, clavicle angle) and sagittal alignment (sagittal vertical axis, thoracic kyphosis, lumbar lordosis). In our study, there were no significant differences between the two groups with respect to demographics or curve characteristics (P > 0.05). In Group A, thoracic and lumbar curvature correction rates were 71.2% and 66.8% respectively, and in Group B they were 71.2% and 73.3%, respectively (P = 0.664 and 0.09). There were no significant differences between the two groups in coronal or sagittal factors (P > 0.05) except for greater postoperative lumbar lordosis in the CCM group (P < 0.001). In conclusion, Ti and CCM rods showed similar correction rates in the sagittal and coronal planes for the surgical correction of AIS with double major curves. Biomechanical studies of Ti and CCM rods in vitro is different in biological condition.

Efficacy of cortico/cancellous composite allograft in treatment of cervical spondylosis.

This was a prospective comparative study.The aim of this study was to compare the clinical and radiologic outcomes of patients treated with cortico/cancellous composite allograft or autoiliac bone graft in anterior cervical discectomy and fusion.Several methods have been developed to fuse the cervical spine for treatment of cervical spondylosis. Cortico/cancellous composite allograft might be another alternative.A total of 46 patients who underwent surgery for treatment of cervical spondylosis were evaluated between September 2010 and January 2015. The duration of operation, blood loss, perioperative complications, neck disability index (NDI), visual analogue scale (VAS), and fusion rates were compared between the 2 groups.There were no significant differences in clinical or radiologic outcomes between the patients treated with cortico/cancellous composite allograft and those treated with autoiliac bone graft. The 2 groups showed similar improvements in clinical symptoms and fusion rates. Although not statistically significant, the subsidence rate was lower in the cortico/cancellous composite group.Cortico/cancellous composite allograft is an effective alternative to conventional allograft or autograft in anterior cervical discectomy and fusion.

Upper cervical spine instability in pseudoachondroplasia.

BACKGROUND: Pseudoachondroplasia (PSACH) is a rare autosomal dominant skeletal dysplasia associated with os odontoideum and atlantoaxial instability. This study aims to define the characteristics of upper cervical spine instability in patients with PSACH and analyze the relation between the incidence of upper cervical instability and os odontoideum. METHODS: Fifteen patients (10 women and 5 men) with PSACH of Korean ethnicity with mean age of 23.7 years (range, 3-44 years) at presentation to our hospital with varied complaints, including short stature, limb deformity, neck pain, and neurological symptoms, were evaluated clinicoradiologically for upper cervical spine instability. The patients were separated into group 1 (n = 9) with os odontoideum and group 2 (n = 6) without os odontoideum. Comparisons were made using parameters such as instability index, rotational instability, atlantodens interval and space available for cord, and analysis done to correlate cervical instability with age and Japanese Orthopedic Association (JOA) score. RESULTS: Significant differences were found statistically when the 2 groups were compared on the basis of the space available for the cord (SAC), JOA scoring, and rotational instability. Linear relationship was found between instability and age and JOA score. Incidence of os odontoideum was 60% in our study group. CONCLUSIONS: Os odontoideum led to an increase in the incidence of upper cervical spine instability. Instability increased with the age. The presence of os odontoideum and atlantoaxial instability did not warrant for surgery because no signs of cervical myelopathy developed or progressed in our patients during the follow-up period, but these patients should undergo regular clinical and radiological evaluation. LEVEL OF EVIDENCE: Level IV prognostic study.