Purpose: This prospective study was conducted to evaluate correction of post-traumatic deformity of the thoracolumbar and lumbar spine at consolidation after posterior instrumentation associated with transpedicular graft. Material and method: The analysis began in 1998 and included 11 patients (mean age 37 years, age range 19–62 years) with lumbar (two L2) or thoracolumbar (four T12 and five L1) fractures. The Magerl classification was A1=2, A2=3, mixed=3. Inclusion criteria were: age < 65 years, regional kyphosis > 10°), intact pedicles, relative gain on local and/or regional kyphosis peroperatively > 70% after correction for reduction-distraction. Posterior instrumentation used the V-V assembly in two cases and 2VV-1VC assembly in nine. Evaluation criteria were, postoperatively and at consolidation: local kyphosis, corrected regional kyphosis, Cobb angle in the frontal plane. Autologous graft tissue harvested from the iliac crest was introduced via the right and left pedicle into the damaged vertebra using an adapted funnel after raising the vertebral plate with a spatula. Results: Mean follow-up was 11 months (range 8–18). Associated procedures were laminectomy in three cases and posterior graft in two. Preoperatively local kyphosis was 19° (12° to 37°) and regional kyphosis was 17° (10° to 35°). Postoperatively, local and regional kyphosis were 4.5° (0–11°) and −2° (−10 to 5°) giving a mean relative gain of 80% (SD = 0.1). Mean relative gain at consolidation was 75% (SD = 0.2 for local kyphosis and 86% for regional kyphosis. The correction was statistically significant. There was no significant difference between the correction postoperatively and at consolidation. Discussion: Transpedicular grafting associated with posterior instrumentation can avoid anterior access in a certain number of cases. Indications are fractures in patients under 65 years of age with a regional kyphosis > 10° and an important anterior defect after reduction (> 40% reduction in height). All patients achieved bone healing without significant loss of correction. The limitations of this technique include the requirement for intact pedicles, a posterior wall displacement of less than 60% and a peroperative relative gain greater than 70% for the local and/or regional kyphosis. An anterior approach must be associated in other cases. Conclusion: Transpedicular grafting is a simple technique allowing true reconstruction of the vertebral body. It can avoid a certain number of supplementary anterior approaches

Purpose of the study: We report the results of a series of seven cases of non-tuberculos infectious lumbar spondylodiscitis treated by posterior instrumentation and secondary anterior curettage of the infectious focus with bone grafting. This particular osteosynthesis method produces a short monosegmentary fixation limited to the space of the infected disc. Material and methods: The series included six men and one woman (mean age 61.7 years, age range 37–82 years). The causal germ was identified in all cases: Staphylococcus aureus in five, and in one each, Staphylococcus epidermidis and Pseudomonas aeruginosa. Levels were L1L2 in one, L2L3 in two, L3L4 in three and L5S1 in one. Predisposing factors were history of prostatic cancer in two patients, coronary heart disease in one and chronic renal failure in one. One patient had received corticosteroid injections and two had no recognized co-morbid conditions. The surgical procedure was undertaken due to persistent pain in three patients (one with quadriceps amyotrophy and weakness), spinal instability with risk of neurological injury in two, and after failure of medical treatment in two patients who had persistent abscesses. Results: Excepting one patient who died from renal failure four months after the surgical procedure, mean follow-up was 31.5 months (range six months to six years). Outcome was excellent in four patients, good in one, and a failure in one patient who was operated on because of instability. Failure of the instrumentation required surgical revision to extend the initial assembly. At last follow-up, all patients had achieved fusion of the instrumented zone and were considered to be cured of their infection. Discussion: Classically, it is advisable to avoid instrumenting close to an infectious area in order to avoid the vicious circle of infection. Configurations described in the literature are usually extensive, blocking healthy levels beyond the infected area and compromising spinal mobility. However, a short instrumentation limited to one segment can be proposed when the end plates at the outer limits of the infectious focus are theoretically healthy. Careful analysis of the imaging data is required to carefully select patients who can benefit from this short configuration. Magnetic resonance imaging is most helpful

Inßuence of scoliosis surgery on pulmonary changes and even upon thoracic deformity changes are still controversial. The purpose of the study was to determine thoracic volume (TV) changes in patients operated on by means of posterior and anterior surgery because of severe thoracic AIS. 50 patients, operated by þrst author randomly chosen from the period 1993–97 were selected. In 25 patients (21 girls, 4 boys) anterior instrumentation was used (group 1), and posterior instrumentation in other 25 patients (20 girls, 5 boys; group 2). TV calculation was performed basing on preoperative and postoperative plain x-rays, using a well known equation (second and third, independent author). The curves were 73û ± 12.4 pre op, and 19û ± 15 post op (group 1), and 75û ±13 pre op., 37û± 10 post op. (group2). Calculated TV for group 1 increased from 5234 ml to 6043 ml postoperatively (17% ± 16). In group 2, TV increased from 5155 to 5489 to 4,371 (6% ± 7). The correlation between the Cobb angle change and the thoracic volume change was poor (+0.2 for group 1, -0.4 for group 2). To determine the role of frontal, sagital and vertical thoracic diameters in TV increase, further correlation tests were performed. The best correlation was found between the frontal and vertical diameter increase in anterior instrumentation (r=0.62; 0.71), whereas the best correlation was found between TV and sagital parameters in posterior instrumentation (r=0.74). It is concluded that anterior instrumentation can increase TV more than posterior instrumentation

Open anterior surgery, including release and instrumentation, is a widely used technique for correction of dorsal and dorsolumbar curves. In the past we have used various different devices to maintain correction. These include Dwyer cable, Zeilke rods, Webb-Morley rods, vertebral staples and the Kaneda system. Any of these can be combined with posterior correction, stabilization and grafting. Several of these techniques have been successfully adapted for the treatment of our cases in Egypt. We encounter severe deformities due to their late presentation. Over the last five years we have used anterior endoscopic release. All had posterior instrumentation. Results: We did anterior release in 20 scoliosis cases and corpectomy in 10 cases. These were compared with another twenty cases who were treated by open anterior and posterior surgery. The results are very encouraging regarding degree of correction; hospital stay; and costs as compared with our historical series of conventional two-stage surgery. There are a number of constraints on using endoscopic techniques. Surgeons require long training and close co-operation. It is contraindicated in those cases with adhesions and patients unfit for one lung anaesthesia. We found the technique is safe and effective. We recommend it for treatment of rigid curves to gain good results and to reduce hospital costs

Both posterior and anterior surgery have potential for complete scoliosis correction. Significant difference in judging the procedures still persists. Aim. To establish objective advantages and risks of the procedures, basing upon long term results. Method. From 1982–2007, 859 anterior(A) and 388 posterior(P) instrumentations were performed by the same surgeon. Single level thoracotomy used even in double curves. Spinal canal was never opened, rib heads left intact, ribs were fractured at the top of rib hump. Zielke rod was used for correction, and another rod added for aditional correction and stabilisation. Various posterior instrumentations were used. Results. CORRECTION (A)frontal 67-45-16(76%), sagital +6, (P)frontal 66-44-29(56%), sag+3; OP. TIME (A)140(50–300), (P)155(110–350); BLOOD REPL. (A)18%, (P)92%; HOSP STAY (A)10, (P)13; VC (A)-10%, (P)0%; SPORT ACT. (A)3mths, (P)12mths; MAJOR COMPLICATIONS: no deaths, (A)1 aorta rupture, 1 bronchus penetration, 0,7% haematothorax, 0,6% reinstrumentation, 0,7% infections demanding op, (P)2 paraplegia (0,5%), 3.9% infections, 4.9% reinstrumentation. Discussion. (A)required no neuromonitoring, no intensive care unit. Blood replacement was occasionally used only for double curves (11 segm), and in preop. anemia. Most of the complications were preventable. Hospitalisation was longer in (P) group due to wound problems. Pulmonary decrease was found only in curves greater than 100 °. Halo traction improved VC, but both instr. had no influence on further improv. In (A)VC recovered in 6 months. Conclusions. (A) can be performed in less radical and agressive way. Anterior release significantly mobilizes the spine and decreases necessary corrective forces. Infection was more frequent in (P) but consequences were more dramatic in (A). All major complications in (A) were preventable. There is temporary decrease in pulmonary function after (A). We could not find objectives for (A) to have more morbidity than (P). Due to superior results we still prefer (A) in surgery of AIS. Our indications for (P) is VC<40%, age, poor bone quality, surgery in upper thoracic spine

Introduction

Transosseous flexion-distraction injuries of the spine typically require surgical intervention by stabilizing the fractured vertebra during healing with a pedicle-screw-rod constructs. As healing is taking place the load shifts from the implant back to the spine. Monitoring the load-induced deflection of the rods over time would allow quantifiable postoperative assessment of healing progress without the need for radiation exposure or frequent hospital visits. This approach, previously demonstrated to be effective in assessing fracture healing in long bones and monitoring posterolateral spinal fusion in sheep, is now being investigated for its potential in evaluating lumbar vertebra transosseous fracture healing.

Aim: To test the null hypothesis that interbody cage fusion does not improve clinical outcome.

Methods and materials: This is a prospective study of 87 patients. Seventy-one of the 87 patients followed to the conclusion of the study at two years. Inclusion criteria: Patients undergoing interbody cage fusion with the Ray threaded cage, made of Titanium, and posterior stabilisation with Diapason pedicle screw instrumentation, all operated by the same surgeon. Exclusions: Surgery for infection, or tumour. Tools used for assessment: Oswestry low back pain questionnaire; Visual analogue pain score (VAS); SF36 general health questionnaire. Assessment time points were 1) Pre-op, and post-operatively at 2) 3 months, 3) 6 months, 4) 1 year and 5) 2 years. SF 36 was introduced later recruiting 71 of the 87 patients.

Results: There were 31 males and 56 females. Average age was 46 years (range 14–76) Fifty-one of the patients had no previous surgery, while 36 had previous surgery.

There was a significant, gradual improvement in symptoms of an average of 20 points (p< .001) over the first year on the Oswestry score. However, this plateaued between the first and second years. Over two years there was a greater than 20 point increase in all but three concepts of SF36, general health, reported health and mental health improving around 15 points (p< .001). Sixty-five per cent of the patients reported an overall improvement and 12% were worse, with most changes occurring in the first year.

In assessing the symptoms with Oswestry questionnaire there was a significant difference between first time and revision surgical groups. The revision group showed an improvement of 11 points (p< .001) at two years, most occurring in the latter part of the first year followed by some deterioration between the first and second years. In the primary surgery group there is a 28 point (p< .0001) improvement by two years. Most of the improvement in the primary group is achieved by the first six months.

Conclusions: Interbody fusion can significantly improve health and function assessed by Oswestry and SF36 outcome tools. Additional observations – unsatisfactory outcome in 12% of patients; expected progress at fixed times after surgery can assist planned rehabilitation. This paper introduces the concept of time staged assessment of symptoms in spinal fusion.

Aim: In sub-axial cervical vertebrae the lamina appears to project perpendicular to the ipsilateral pedicle axis, and forms a reliable trajectory for avoidance of vertebral artery injury in lateral mass (LM) screw placement: the aim is to confirm these observations.

Material and Methods: 51 digital cervical spine CTs (255 vertebrae; 25 female 26 male; mean age 37.4 range:18–80). Exclusions: Severe degeneration, malformation, tumour, trauma.

Measurement (axial view):

Angle of ipsilateral outer lamina cortex to pedicle axis

Results: Average lamina-pedicle angle (standard deviation):

Females: Right: C3–84.8°(2.6), C4–85.2°(3.1), C5–86.7°(3.3), C6–89.2°(2.5), C7–92.3°(2.4);

Conclusion: The angle formed by the lamina and ipsilateral pedicle ranges from 84° at C3 to 92° at C7. Although the angle is not exactly perpendicular at all levels as hypothesised, the lamina forms a useful reference plane for pedicle screw insertion in the sub-axial cervical spine.

LM screws placed parallel to the lamina find sufficient LM width and are highly unlikely to injure the vertebral artery in bi-cortical placement. This technique appears favourable over conventional 30° LM placement.

Ethics approval: None needed

Interest Statement: None

Introduction: In rigid AIS, the main resistance for thoracic derotation are the anteriorly rotated ribs on the concavity. This study presents clinical and radiographic long term results of the CTP, which is a routine surgical procedure at the authors’ institution.

Material and Methods: Between 1996 and 1997 we have operated on 466 cases of scoliosis. 36 patients with thoracic AIS were evaluated. Technique: The ribs on the concave side are osteotomised close to the costo-transverse joint and elevated over the bended rod.

Results: Mean follow up was 6.4 y. Mean preoperative side bending flexibility was 21%. Mean correction rate was 68%, mean rib hump correction was 3cm. Mean loss of correction 4°. There was no neurological complication, and pulmonary morbidity was not increased.

Conclusion: In rigid thoracic scoliosis, a release of the concave ribs by means of the CTP can both significantly increase the extent of correction and contributes to an excellent cosmetic result.

Background and Purpose: Tuberculosis is a common cause of mortality and morbidity in our country. Late neurological deficits following conservative management can occur though not very common. Deformity correction and decompression at a single sitting in a healed tuberculous spine is a massive undertaking and it requires experience and appropriate technique to achieve a good correction.

Materials and Methods: We operated upon 22 patients with a deformed spine and a progressive neurological deficit following healed tuberculosis. All patients complained of pain and found the cosmetic appearance unacceptable. The average age was 29 years {19 – 35 years}. All patients had completed a course of four drugs anti tuberculous chemotherapy for a minimum period of 12 months. All patients were screened for disease activity before surgery. The average Konstam angle before surgery was 86 degrees {80–105 degrees}. All patients underwent single stage surgical correction by a posterior based pedicle subtraction osteotomy with excision of the internal gibbus and further decompression and posterior stabilization using a screw rod construct. The local bone chips removed during the surgical procedure was used to promote fusion.

Results: We achieved an average kyphosis correction of 60 degrees {52–75 degrees}. At an average follow up of 18 months the average loss of correction was 3 degrees. The mean operating time was 165 minutes {120 – 210 minutes}. The mean blood loss was 800 ml {700–1100 ml}. All patients had significant improvement in their post operative pain scores and disability outcome measures. All patients were greatly satisfied with the cosmetic result obtained. There were no major intra operative or post operative complications.

Conclusion: Transpedicular three-column osteotomy uses a posterior approach and generally leaves no gap anteriorly. The anterior column is not opened as in a Smith-Petersen osteotomy. Posterior approach offers access to all three columns of the spine and avoids the morbidity associated with the anterior approach. The internal gibbus can be addressed and the normal posterior bony elements in tuberculosis can be used for achieving fusion.

Introduction: Some authors (Suk, Barr, Hamill ...) showed that lumbar and thoracic pedicle screws provided adequate reduction of scoliosis. Quality of reduction depends on primary stability of the vertebral anchors. If the anchor has a good primary stability, reduction forces are entirely transferred to the vertebra, which results in reduction of the deformity, whereas, if the anchor has a poor primary stability, it will move when subjected to reduction forces, and this will result in inadequate reduction. Lumbar screws which are advocated by many authors, are extensively used. Thoracic screws are only used by a limited number of surgeons, as most surgeons favour hooks. Polyaxiality facilitates rod positioning; it eliminates the orthogonal stresses that are generated during tightening and which are known to be responsible for screw fracture. The drawback manoeuvre consists in applying forces directly to the vertebra via the anchor; the deformity is reduced by gently translating the vertebra towards the rod. The polyaxial vertebral claw that we are presenting here is a self-stabilising implant that provides the same primary stability as the screw and allows application of multidirectional drawback forces.

Materials and methods: The system consists of self-stabilising vertebral anchors, either screws or claws. Each anchor is polyaxial and features a threaded extension that allows translation of the vertebra towards the rod. Connection of the screw or claw to the rod is provided by connecting clamps. The first operative step consists of inserting the vertebral anchors, favouring the apex of the deformity. The insertion technique is described in detail. The claw is locked independently, prior to securing the rod on to the claw. The second operative step consists of positioning the rods which are bent to the ideal sagittal curve. Polyaxiality and threaded extensions make rod positioning an easy step. Progressive tightening of the nuts results in correction of the deformity as it slowly moves the vertebrae towards the rods. The translation force is distributed over all the anchors, ensuring a gentle reduction manoeuvre with no risk of back out of the implants. Approaching vertebrae at the end of the reduction manoeuvre results in vertebral derotation. It is not necessary to use distraction which is considered hazardous.

Results: 35 such instrumentations have been used in patients with idiopathic scoliosis over the previous 12 months. We have used an average of nine screws and four claws per patient, mainly thoracic pedicle/transverse claws. Main curve correction was 71% (average curve was 59° preoperatively and 17° postoperatively). Average correction of the uninstrumented lumbar curve was 73%. The upper curve improved from 34° to 15°. The slope of the first uninstrumented vertebra was 14° pre-operatively and 6° postoperatively. In the sagittal plane, the average angle of thoracic kyphosis in hollow backs (kyphosis less than 15°) was 9°, increasing up to 27° postoperatively.

Discussion: This instrumentation is characterised by stable implants which provide a quality of reduction similar to that achieved with pedicle screws. Vertebral claws are easy to insert and have a better primary stability than screws.

Poly-axiality is a common feature to all the implants of this system; it greatly facilitates placement of the implants and allows to apply traction simultaneously to all the anchors, which results in progressive, gentle reduction. Simultaneous traction application ensures adequate correction of the thoracic kyphosis (gain of 18°). As a matter of fact, severe kyphosis can be bent into the rods, and translation of the vertebrae towards the rods is very easy. Adequate reduction of the main curve results in correction of the underlying lumbar curve and shifting of the first uninstrumented vertebra into a more horizontal position.

Conclusion: This instrumentation based on stable poly-axial implants, should allow to improve the quality of reduction of scoliosis.

Objective: To evaluate the effect of spinal fusion from T1, T2 to the sacrum with pelvic fixation using unit rod instrumentation on the ambulatory potential of pediatric patients with cerebral palsy.

Study Design: A retrospective study of 24 ambulatory pediatric patients with spastic cerebral palsy and neuro-muscular scoliosis was performed.

Summary of Background Data: Spinal deformities, occurring in patients with cerebral palsy and good ambulatory capacity, are infrequently associated with pelvic obliquity, and so instrumented spinal fusions traditionally do not extend to the pelvis.

Methods: The medical charts and radiographs were reviewed, and the patients’ ambulatory ability was assessed clinically, with video tape or complete gait analysis. A questionnaire assessing patients’ functional improvement was given to the caretakers.

Results: The study group included 17 female and 7 male patients, 19 quadriplegics and 5 diplegics. Follow-up evaluations for ambulatory function occurred at a mean of 2.86 years after surgery. Mean age at surgery was 15.4 years. Twenty patients underwent posterior spinal fusions and 4 patients combined anterior-posterior procedures. The patients were evaluated clinically pre-operatively, postoperatively and at follow-up with no alteration in their ambulatory status, except one patient who developed bilateral hip heterotopic ossification and gradually lost her ability to ambulate. Thirteen patients had both preoperative and postoperative gait analysis, showing no change in their ambulatory function. The surgical outcome survey demonstrated significant improvement in the child’s physical appearance, head and trunk balance, sitting ability, amount of back pain, respiration, and no change in ambulatory capacity.

Conclusions: Spine surgery with fusion extending to the pelvis in ambulatory patients with cerebral palsy provided excellent deformity correction and preserved their ambulatory function.

Purpose: A retrospective study comparing the fusion rate and, the incidence of junctional spinal stenosis between a rigid (Wiltse) and a semirigid (Varifix) posterior spinal fusion system.

Material & Methods: 92 patients, mean age 52.3 year old, underwent posterior fusion with semirigid Varifix system (rod diameter 5.0 mm), and 89 patients, mean age 49.8 year old, with rigid Wiltse system (6.5 mm). The mean follow-up was 4.8 years (range 2–9) for Varifix group and 11.7 years (range 9–17) for Wiltse group. Preoperative diagnosis was spinal stenosis (n=56), disc degenerative disease (n=43), degenerative spondylolisthesis (n=37), post-laminectomy instability (n=34), and isthmic spondylolisthesis (n=11). In all patients autologous iliac crest bone graft was used. Spinal fusion was confirmed by A-P, lateral, and flexion-extension radiographic studies, or by direct surgical exploration and observation. Pain intensity was recorded using the Visual Analogue Scale (VAS).

Results: Successful fusion was achieved in 92.4% in the semirigid group and in 93.2% for the rigid group. There was no statistical difference in fusion rate between these two groups (p=0.82). Eight patients with pseudoarthrosis were treated by anterior fusion and 5 by repaired posterior fusion, with a fusion rate of 100%. Postoperative infection was diagnosed in 5 patients (5.4%) in the semirigid group and in 4 patients (4.5%) in the rigid group. They were treated by debridement, irrigation, and intravenous antibiotics. Hardware removal because of pain was performed in 9 patients (9.8%) in the semirigid group, and 17 patients (19.1%) in rigid group. Removal of hardware resulted in improvement in pain in all patients. Junctional spinal stenosis was diagnosed in 2 patients (2.2%) in semirigid group and in 7 patients (7.9%) in rigid group. There was a trend for higher incidence of adjacent level stenosis in rigid group (p=0.07).

Conclusion: Biomechanical studies have shown that the stiffness of spinal construct depends on rod diameter and a decrease in rod rigidity can increase the risk of implant failure. In our study we didn’t find any difference in the fusion rate and in complication rate between these two systems. The increased percentage of the junctional spinal stenosis in rigid group may be explained by the longer follow-up in this group. According to our data the semirigid system may be better tolerated than the rigid system.

Objective: To evaluate the outcome of spinal fusion with unit rod in pediatric patients with cerebral palsy who were treated by the two senior authors using the same operative technique.

Study Design-Methods: This is a retrospective study of 288 patients with mean age at surgery 13.9 years (SD: 3.26), whose medical charts and radiographs were reviewed. A questionnaire including 14 questions assessing patients’ functional improvement was given to the caretakers.

Results: Mean radiographic follow up of 3.2 years (range: 1–9.9) was available in 213 patients. In 46 patients anterior-posterior fusion was performed and in 242 only posterior. The preop. Cobb angle was 740(range: 6–176o) corrected by 68% to 230 (p< .01) and increased by 20 in the last follow-up (p< .01). The preop. pelvic obliquity was 170(range: 0–57o), corrected by 73% to 4.70 (p< .01) and increased by 0.40 at follow-up. The preop. kyphosis angle was 560(range: −44–130o), corrected by 37% to 350 (p< .01) and increased by 20 at follow-up. The preop. lordosis angle was 380(range: −50–140o), corrected by 14% to 430 (p< .05) and increased by 1.40 at follow-up. There was a strong correlation between hyperlordosis and days of hospitalization, blood loss and surgical time (r= −.22,. 23,. 24). Patients with lordotic angle > 600 developed 15.1% technical problems related to pelvic fixation, whereas only 3.4% of those with < 600. The mean days of hospitalization were 19.6, the mean blood loss 2.9lt (1.2BV), the mean surgical time 4.4h (Anterior-Posterior: 7h, Posterior only: 3.9h) and the mean ICU stay 5 days. There was a difference only in surgical time (p< .01) if an anterior procedure was required. The major complications included 3 perioperative deaths, 14 deep infections, 13 (4.5%) reoperations for mechanical problems and no detected pseudarthrosis. The answers received by the caretakers were 99% positive, emphasizing the improvement in child’s appearance, sitting ability and respiratory function.

Conclusions: Spine surgery in patients with cerebral palsy was accompanied by a considerable blood loss and multiple medical complications. A very satisfactory correction of spinal curvatures was achieved and maintained in follow up. Excessive lumbar lordosis was associated with a high incidence of technical problems and an increased morbidity. There were no pseudarthrosis and the overall number of reoperations for technical reasons was very low. The caretakers were extremely pleased with the outcome of this procedure. Unit rod is a very effective instrumentation system, providing excellent results and a low mechanical complication rate in the treatment of cerebral palsy patients with spinal deformities.

Introduction. In daily clinical practice, progression of spinal fusion is typically monitored during clinical follow-up using conventional radiography and Computed Tomography scans. However, recent research has demonstrated the potential of implant load monitoring to assess posterolateral spinal fusion in an in-vivo sheep model. The question arises to whether such a strain sensing system could be used to monitor bone fusion following lumbar interbody fusion surgery, where the intervertebral space is supported by a cage. Therefore, the aim of this study was to test human cadaveric lumbar spines in two states: after a transforaminal lumbar interbody fusion (TLIF) procedure combined with a pedicle-screw-rod-construct (PSR) and subsequently after simulating bone fusion. The study hypothesized that the load on the posterior instrumentation decreases as the segment stiffens due to simulated fusion. Method. A TLIF procedure with PSR was performed on eight human cadaveric spines at level L4-L5. Strain sensors were attached bilaterally to the rods to derive implant load changes during unconstrained flexion-extension (FE), lateral bending (LB) and axial rotation (AR) loads up to ±7.5Nm. The specimens were retested after simulating bone fusion between vertebrae L4-L5. In addition, the range of motion (ROM) was measured during each loading mode. Result. The ROM decreased in the simulated bone fusion state in all loading directions (p≤0.002). In both states, the measured strain on the posterior instrumentation was highest during LB motion. Furthermore, the sensors detected a significant decrease in the load induced rod strain (p≤0.002) between TLIF+PSR and simulated bone fusion state in LB. Conclusion. Implant load measured via rod strain sensors can be used to monitor the progression of fusion after a TLIF procedure when measured during LB of the lumbar spine. However, further research is needed to investigate the influence of daily loading scenarios expected in-vivo on the overall change in implant load

Aims. A variety of surgical methods and strategies have been demonstrated for Andersson lesion (AL) therapy. In 2011, we proposed and identified the feasibility of stabilizing the spine without curettaging the vertebral or discovertebral lesion to cure non-kyphotic AL. Additionally, due to the excellent reunion ability of ankylosing spondylitis, we further came up with minimally invasive spinal surgery (MIS) to avoid the need for both bone graft and lesion curettage in AL surgery. However, there is a paucity of research into the comparison between open spinal fusion (OSF) and early MIS in the treatment of AL. The purpose of this study was to investigate and compare the clinical outcomes and radiological evaluation of our early MIS approach and OSF for AL. Methods. A total of 39 patients diagnosed with AL who underwent surgery from January 2004 to December 2022 were retrospectively screened for eligibility. Patients with AL were divided into an MIS group and an OSF group. The primary outcomes were union of the lesion on radiograph and CT, as well as the visual analogue scale (VAS) and Oswestry Disability Index (ODI) scores immediately after surgery, and at the follow-up (mean 29 months (standard error (SE) 9)). The secondary outcomes were total blood loss during surgery, operating time, and improvement in the radiological parameters: global and local kyphosis, sagittal vertical axis, sagittal alignment, and chin-brow vertical angle immediately after surgery and at the follow-up. Results. Data for 30 patients with AL were evaluated: 14 in the MIS group and 16 in the OSF group. All patients were followed up after surgery; no nonunion complications or instrumentation failures were observed in either group. No significant differences in the VAS and ODI scores were identified between the two groups. Mean ODI improved from 51 (SE 5) to 17 (SE 5) in the MIS group and from 52 (SE 6) to 19 (SE 5) in the OSF group at the follow-up. There were significant improvements in total blood loss (p = 0.025) and operating time (p < 0.001) between the groups. There was also no significant difference in local kyphosis six months postoperatively (p = 0.119). Conclusion. Early MIS is an effective treatment for AL. MIS provides comparable clinical outcomes to those treated with OSF, with less total blood loss and shorter operating time. Our results support and identify the feasibility of solid immobilization achieved by posterior instrumentation without bone graft via MIS for the treatment of AL. Cite this article: Bone Jt Open 2024;5(10):886–893

The development of spinal deformity in children with underlying neurodisability can affect their ability to function and impact on their quality of life, as well as compromise provision of nursing care. Patients with neuromuscular spinal deformity are among the most challenging due to the number and complexity of medical comorbidities that increase the risk for severe intraoperative or postoperative complications. A multidisciplinary approach is mandatory at every stage to ensure that all nonoperative measures have been applied, and that the treatment goals have been clearly defined and agreed with the family. This will involve input from multiple specialities, including allied healthcare professionals, such as physiotherapists and wheelchair services. Surgery should be considered when there is significant impact on the patients’ quality of life, which is usually due to poor sitting balance, back or costo-pelvic pain, respiratory complications, or problems with self-care and feeding. Meticulous preoperative assessment is required, along with careful consideration of the nature of the deformity and the problems that it is causing. Surgery can achieve good curve correction and results in high levels of satisfaction from the patients and their caregivers. Modern modular posterior instrumentation systems allow an effective deformity correction. However, the risks of surgery remain high, and involvement of the family at all stages of decision-making is required in order to balance the risks and anticipated gains of the procedure, and to select those patients who can mostly benefit from spinal correction

Use of ultrasonic bone scalpel (UBS) is becoming popular in spinal surgery. This study presents the safety profile of UBS for posterior release in surgical correction of adolescent idiopathic scoliosis (AIS). From 2016 to 2018, UBS (Misonix) was used by the senior author in a variety of spinal operations. Data for intraoperative complications when this devise was used for posterior correction of AIS were collected. Revision cases were excluded. UBS was used for posterior release of AIS in 65 patients (58 female, seven male) with an average age of 15.6 years (range 11–23). Average length of posterior instrumentation was 12 levels (range 6–14). Instrumentation was exclusively from T2 to L4. To achieve adequate release for correction, UBS was used to perform a total of 644 modified in-situ chevron osteotomies (average ten, range six to 12) and 31 rib osteotomies. Overall, three complications (4.6 %) were directly related to the use of UBS: one haemopneumothorax, which was successfully treated with a chest drain; and two loss of motor-evoked potentials during monitoring, which led to the postponement of the final correction. These two patients did not have any neurological problems and their surgery was completed successfully within 1 week of the initial surgery. One late deep infection was reported. This was not thought to be directly related to the use of UBS. Use of UBS in the posterior surgical treatment of AIS appears to be relatively safe with a low level of acceptable complications. However, appropriate training is required for the use of UBS

Background. It is known that severe cases of intervertebral disc (IVD) disease may lead to the loss of natural intervertebral height, which can cause radiating pain throughout the lower back and legs. To this point, surgeons perform lumbar fusion using interbody cages, posterior instrumentation and bone graft to fuse adjacent vertebrae together, thus restoring the intervertebral height and alleviating the pain. However, this surgical procedure greatly decreases the range of motion (ROM) of the treated segment, mainly caused by high cage stiffness. Additive manufacturing can be an interesting tool to reduce the cage's elastic modulus (E), by adding porosity (P) in its design. A porous cage may lead to an improved osteointegration since there is more volume in which bone can grow. This work aims to develop a finite element model (FEM) of the L4-L5 functional spinal unit (FSU) and investigate the loss of ROM induced by solid and porous cages. Materials and Methods. The Intact-FEM of L4-L5 was created, which considered the vertebrae, IVD and ligaments with their respective material properties. 1. The model was validated by comparing its ROM with that of other studies. Moments of 10 Nm were applied on top of L4 while the bottom of L5 was fixed to simulate flexion, extension, lateral bending and axial rotation. 2. The lumbar cages, posterior instrumentation and bone graft were then modelled to create the Cage-FEMs. Titanium was chosen for the instrumentation and cages. Cages with different stiffness were considered to represent porous structures. The solid cage had the highest modulus (E. 0. =110 GPa, P. 0. =0%) whereas the porous cages were simulated by lowering the modulus (E. 1. =32.8 GPa, P. 1. =55%; E. 2. =13.9 GPa, P. 2. =76%; E. 3. =5.52 GPa, P. 3. =89%; E. 4. =0.604 GPa, P. 4. =98%), following the literature. 3. The IVD was removed in Cage-FEMs to allow the implant's insertion [Fig. 1] and the previous loading scenarios were simulated to assess the effects of cage porosity on ROM. Results. The Intact-FEM presents acceptable ROM according to experimental and numerical studies, as shown by the red line in Figure 2. After insertion, lower ROM values in Cage-FEMs are measured for each physiological movement [Fig. 3]. In addition, highly porous cages have greater ROM, especially in axial rotation. Discussion. Significant reduction of ROM is expected after cage insertion because the main goal of interbody fusion is to allow bone growth. As such, the procedure's success is highly dependent on segmental stability, which is achieved by using cages in combination with bone graft and posterior instrumentation. Furthermore, higher cage porosities seem to affect the FSU. In fact, ROM increases more as the cage modulus approaches that of the cancellous bone (E. canc-bone. =0.2 GPa. 1. ). Next step will be to assess the effects of cage design on the L4-L5 FSU mechanical behavior and stress distribution. To conclude, additive manufacturing offers promising possibilities regarding implant optimization, being able to create porous cages, thus reducing their stiffness. For any figures or tables, please contact the authors directly

Introduction. Pedicle screw loosening in posterior instrumentation of thoracolumbar spine occurs up to 60% in osteoporotic patients. These complications may be alleviated using more flexible implant materials and novel designs that could be optimized with reliable computational modeling. This study aimed to develop and validate non-linear homogenized finite element (hFE) simulations to predict pedicle screw toggling. Method. Ten cadaveric vertebral bodies (L1-L5) from two female and three male elderly donors were scanned with high-resolution peripheral quantitative computed tomography (HR-pQCT, Scanco Medical) and instrumented with pedicle screws made of carbon fiber-reinforced polyether-etherketone (CF/PEEK). Sample-specific 3D-printed guides ensured standardized instrumentation, embedding, and loading procedures. The samples were biomechanically tested to failure in a toggling setup using an electrodynamic testing machine (Acumen, MTS) applying a quasi-static cyclic testing protocol of three ramps with exponentially increasing peak (1, 2 and 4 mm) and constant valley displacements. Implant-bone kinematics were assessed with a stereographic 3D motion tracking camera system (Aramis SRX, GOM). hFE models with non-linear, homogenized bone material properties including a strain-based damage criterion were developed based on intact HR-pQCT and instrumented 3D C-arm scans. The experimental loading conditions were imposed, the maximum load per cycle was calculated and compared to the experimental results. HR-pQCT-based bone volume fraction (BV/TV) around the screws was correlated with the experimental peak forces at each displacement level. Result. The nonlinear hFE models accurately (slope = 1.07, intercept = 0.2 N) and precisely (R. 2. = 0.84) predicted the experimental peak forces at each displacement level. BV/TV alone was a weak predictor (R. 2. <0.31). Conclusion. The hFE models enable fast design iterations aiming to reduce the risk of screw loosening in low-density vertebrae. Improved flexible implant designs are expected to contribute to reduced complication rates in osteoporotic patients