Humans ; Internal Fixators ; Lumbar Vertebrae ; surgery ; Spinal Fusion ; instrumentation ; methods ; Spinal Stenosis ; surgery

Humans ; Lumbar Vertebrae ; surgery ; Spinal Diseases ; surgery ; Spinal Fusion ; instrumentation ; methods

We have made a biomechanical evaluation of titanium mesh with anterior plate fixation in anterior cervical decompression. Six fresh cervical spine specimens (C3-7) of young cadavers were used in the biomechanical test. Subtotal vertebrectomy was performed on C5, C5-6 and C4-6. We accomplished two constructions: (1) bone graft; (2) titanium mesh with anterior plate fixation. Then their biomechanic stabilities were tested in all groups and compared with those of intact specimens. We found that titanium mesh with anterior plate fixation improved the stability of the unstable spine, showing a significant difference when compared with that of the intact group (P < 0.05). The anterior cervical interbody fusion by bone graft and the titanium mesh implantation is stabler than the intact cervical sample, and the stability decreases with the increase in number of cervical segment.
Biomechanical Phenomena ; Cadaver ; Cervical Vertebrae ; surgery ; Decompression, Surgical ; instrumentation ; methods ; Humans ; Internal Fixators ; Spinal Fusion ; instrumentation ; methods ; Stress, Mechanical ; Titanium

OBJECTIVETo investigate the anatomical feasibility and the technique of T(1)-T(3) crossing laminar screws fixation in the adult population.

METHODSThere were 33 dry upper thoracic vertebras specimen which included respectively T(1), T(2), T(3) were studied. Spinous process height (Hs), bilateral laminar height (H), length of superior laminar screws (Ls), length of inferior laminar screws (Li), bilateral thickness of laminar (TL) and crossing angle the laminar (A) were measured. On the basis of modified Kretze's technique, T(1) crossing laminar screws implantation was performed under visual control. The crossing laminar screws position were evaluated by X-ray and visualizing.

RESULTSThe mean Hs of T(1) was the highest which was (15.7 ± 1.6) mm; the mean H of T(3) was the highest which was (18.7 ± 1.1) mm; the TL and A of T(1) were (6.3 ± 0.9) mm and 101.8° ± 4.5°, that of T(2) were (6.9 ± 1.0) mm and 101.9° ± 4.3°, that of T(3) were (6.5 ± 0.9) mm and 102.9° ± 4.4°, respectively. There were no significant differences between the values of the H and TL on left and right sides (P > 0.05). The Ls of T(1), T(2), T(3) were shorter than Li of that [(31.7 ± 2.4) mm vs. (37.3 ± 2.3) mm, (25.8 ± 2.2) mm vs. (32.3 ± 2.7) mm, (25.3 ± 2.7) mm vs. (31.2 ± 2.9) mm, respectively]. There was significant statistically difference between the values of the Ls and Li on the same vertebra (P < 0.05). The mean TL of T(2) was the thickest, which was significant statistically thicker than that of T(1) (t = 8.876, P < 0.01), which was not significant statistically thicker than that of T(3) (t = 1.919, P > 0.05). The T(1) crossing laminar screws were successfully placed, without impingement of the spinal canal.

CONCLUSIONSIt is feasible to place T(1), T(2), T(3) crossing laminar screws in most people. This study provides anatomic guidelines to allow for accurate screw selection and insertion.

Adult ; Aged ; Bone Screws ; Feasibility Studies ; Humans ; Middle Aged ; Spinal Fusion ; instrumentation ; methods ; Thoracic Vertebrae ; surgery

The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR.
Adolescent ; *Bone Screws ; Humans ; Orthopedic Procedures/instrumentation/*methods ; Rotation ; Scoliosis/*surgery ; Spinal Fusion

OBJECTIVETo explore the effect of clinical application of stand-alone MC+PEEK cage in anterior cervical fusion.

METHODSFrom January 2011 to January 2014,50 patients were treated with the MC+PEEK cage filled with autogenous cancellous illic-bone graft after anterior cervical discectomy. There were 22 patients with cervical spondylosis,26 patients with traumatic cervical disc herniation, 2 patients with cervical instability in these patients. There were 32 males and 18 females, aged from 30 to 79 years old with an average of 53.30 years old. There were 32 patients with single segment, 15 patients with double segments and 3 patients with three segments. Cervical AP and lateral and the flexion-extension X-rays were regularly taken in order to assess the cervical physiological curvature, the graft fusion and internal fixation related complications. Nerve function, clinical effect and bone fusion were respectively evaluated according to Japan Orthopedic Association (JOA), Otani grade and Suk method.

RESULTSAll patients were followed up from 6 to 36 months with an average of 20 months. No correlated surgical complications were found and all patients obtained bony fusion with an average time of 4.30 months. JOA score had significantly improvement after surgery (P < 0.05). The JOA score was 10.60 ± 3.00 before surgery and 16.10 ± 2.20, 16.40 ± 2.35 at one week and six months after surgery respectively. According to Otani grade,40 cases got excellent results, 9 good, 1 fair. No significant dysphagia and internal fixation related complications such as displacement of cages were found during the follow-up period.

CONCLUSIONUsing this cage in anterior cervical fusion can obtain satisfactory clinical effect with less operation injury and reduce the complications. It is a better fusion method in anterior cervical fusion.

Adult ; Aged ; Cervical Vertebrae ; surgery ; Female ; Humans ; Male ; Middle Aged ; Spinal Fusion ; adverse effects ; instrumentation ; methods

BACKGROUNDAdjacent segment degeneration could seriously affect the long-term prognosis of lumbar fusion. Dynamic fixation such as the interspinous fixation, which is characterized by retaining the motion function of the spinal segment, has obtained satisfactory short-term effects in the clinical setting. But there are few reports about the biomechanical experiments on whether dynamic fixation could prevent adjacent segment degeneration.

METHODSThe surgical segments of all 23 patients were L4/5. Thirteen patients with disc herniation of L4/5 underwent Wallis implantation surgery, and 10 patients with spinal stenosis of L4/5 underwent posterior lumbar interbody fusion (PLIF). L3-S1 segmental stiffness and displacement were measured by a spine stiffness gauge (SSG) device during surgery when the vertebral plate was exposed or during spinal decompression or internal fixation. Five fresh, frozen cadavers were used in the self control experiment, which was carried out in four steps: exposure of the vertebral plate, decompression of the spinal canal, implantation of a Wallis fixing device, and PLIF of L4/5 after removing the Wallis fixing device. Then, L3-S1 segment stiffness was measured by an SSG device.

RESULTSThe experiments showed that the average stiffness of the L4/5 segment was (37.1 ± 8.9) N/mm after exposure of the vertebral plate, while after spinal decompression, the average stiffness fell to (26.2 ± 7.1) N/mm, decreasing by 25.8% (P < 0.05). For the adjacent segments L3/4 and L5/S1, their stiffness showed no significant difference between the L4/5 segment decompression and the exposure of the vertebral plate (P > 0.05). After Wallis implantation of L4/5, the stiffness of the cephalic adjacent segment L3/4 was (45.8 ± 10.7) N/mm, which was 20.5% more than that after the exposure of the vertebral plate (P < 0.05); after L4/5 PLIF surgery, the stiffness of L3/4 was (35.3 ± 10.7) N/mm and was decreased by 12.4% more than that after the exposure of the vertebral plate (P < 0.05). The stiffness of the cephalic adjacent segment L3/4 after fixation in the Wallis group was significantly higher than that of the PLIF group (P < 0.05). Cadaver experiments showed that the stiffness of the cephalic adjacent segment in the Wallis group was significantly higher than that of the PLIF group after L4/5 segment fixation (P < 0.05); the stiffness of the L5/S1 segment showed no significant difference between PLIF surgery and Wallis implantation (P > 0.05).

CONCLUSIONSAfter interspinous (Wallis) fixation, the stiffness of the cephalic adjacent segment increased. After PLIF with pedicle screw fixation, the stiffness of the cephalic adjacent segment decreased. An interspinous fixation system (Wallis) has a protective effect for cephalic adjacent segments for the immediate post-operative state.

Adult ; Bone Screws ; Female ; Humans ; Lumbar Vertebrae ; surgery ; Male ; Middle Aged ; Spinal Fusion ; instrumentation ; methods

OBJECTIVETo evaluate the mid-term effectiveness of nano-hydroxyapatite/polyamide66 (n-HA/PA66) cage in the anterior spinal reconstruction.

METHODSThere were 177 patients who undergone the anterior decompression and fusion with n-HA/PA66 cage and internal fixation between January 2008 and January 2010 included in this study. There were 117 male and 60 female patients aged from 18 to 74 years. The diagnoses included cervical fracture in 47 patients, thoracic or lumbar fracture in 50 patients, cervical spondylopathy in 58 patients, spinal tuberculosis in 17 patients and spinal tumor in 5 patients. The X-ray and three-dimensional CT were followed up in all these patients to observe the spinal alignment, the rate of fusion and the rate of n-HA/PA66 cage subsidence and translocation. The neurological functions of patients with spinal fracture were evaluated by Frankel grading; the improvement of the clinical symptoms of the other patients were assessed by visual analogue scale (VAS) scores and Japan Orthopaedic Association (JOA) scores or SF-36 scores.

RESULTSAll the 177 patients had been followed-up for 36 to 70 months after surgery (average 51 months). Except the slight cage translocation been found in the only one patient with cervical fracture, no cage prolapsed or breakage was exist in our patients up to the last follow-up. In the patients with spinal fracture, the mean time for fusion was 4.5 months, the rate of fusion was 95.9% and the rate of cage subsidence was 5.2%; while in the patients with cervical spondylopathy, the mean time for fusion was 4.4 months, the fusion rate was 96.5% and the subsidence rate was 5.2%; while in patients with spinal tuberculosis, the mean fusion time was 5.5 months, the rate of fusion was 94.0%, the rate of subsidence was 5.9%; and in the patients with tumor, the mean time for fusion was 6.0 months, the fusion rate was 100%, and the cage subsidence was found in only one patient. The preoperative symptoms of each patient were improved to varying degrees after surgery. At the last follow-up, the Frankel grading of patients of spinal fracture with incomplete paralysis improved 0 to 2 classes; the VAS, JOA or SF-36 scores of the other patients were improved significantly than their respective scores before surgery (t = 2.982, 4.126 and 3.980, P < 0.05).

CONCLUSIONSThe n-HA/PA66 cage has much higher rate of osseous fusion and lower cage subsidence, it is an ideal cage which can provide effective restoring and maintaining for the spinal alignment and intervertebral height. Moreover, the mid-term clinical results of anterior reconstruction with this cage in the patients with spinal trauma, degeneration, tuberculosis or tumor are well content.

Adolescent ; Adult ; Aged ; Durapatite ; Female ; Fracture Fixation, Internal ; instrumentation ; Humans ; Male ; Middle Aged ; Nanostructures ; Nylons ; Spinal Diseases ; surgery ; Spinal Fusion ; instrumentation ; methods ; Treatment Outcome ; Young Adult

OBJECTIVETo determine the initial stability of a novel construct in cadaveric cervical spine in comparison with a conventional method.

METHODSTwelve specimens of fresh human cadaveric cervical spines (C(3)-C(7)) were randomly divided into the test group and control group. In the former group, one-level corpectomy of C(5) and three cortical iliac step-cut grafting with absorbable screw fixation was performed, and one-level corpectomy of C(5) and three cortical iliac strut grafting with anterior plate fixation in the control group. Flexibility test and graft push of strength test were carried out before and after grafting and fixation to determine the range of motion (ROM), neutral zone (NZ) and graft push out strength (POS).

RESULTSThe cervical spines of the two groups all had increased initial stability in all 6 rotational degrees of freedom with also enhanced graft POS after fixation. Compared with the control group, the test group had higher stability in extension and comparable stability in flexion and axial rotation, but lower stability in lateral bending. The graft POS after fixation in the test group, however, was lowered in comparison with the control group.

CONCLUSIONStep-cut grafting and absorbable screw fixation provides sufficient stability potential for the cervical spine in vitro and allows optimum biomechanical and biological environments to enhance graft fusion and reduce complications.

Absorbable Implants ; Biomechanical Phenomena ; Bone Screws ; Bone Transplantation ; methods ; Cadaver ; Cervical Vertebrae ; physiopathology ; surgery ; Humans ; Joint Instability ; physiopathology ; prevention & control ; Orthopedic Procedures ; instrumentation ; methods ; Spinal Fusion ; instrumentation ; methods

We performed biomechanical comparison of a xenograft bone plate-screw (XBPS) system for achieving cadaveric lumbar transpedicular stabilization (TS) in dogs. Twenty dogs' cadaveric L2-4 lumbar specimens were harvested and their muscles were removed, but the discs and ligaments were left intact. These specimens were separated to four groups: the L2-4 intact group as control (group I, n = 5), the L3 laminectomy and bilateral facetectomy group (LBF) (group II, n = 5), the LBF plus TS with metal plate-screw group (group III, n = 5) and the LBF plus TS with XBPS group (group IV, n = 5). Five kinds of biomechanical tests were applied to the specimens: flexion, extension, left-right bending and rotation. The averages of the 16 stiffness values were calculated and then these were statistically analyzed. The statistical results show that the XBPS system contributes spinal stability and this system can be a good choice for achieving TS.
Animals ; Biomechanics ; Bone Plates/*veterinary ; Bone Screws/*veterinary ; Cadaver ; Dogs ; Lumbar Vertebrae/physiology/*surgery ; Range of Motion, Articular/physiology ; Spinal Fusion/instrumentation/*methods ; Transplantation, Heterologous/instrumentation/*methods