Aims. Surgical approaches to cervical ossification of the posterior longitudinal ligament (OPLL) remain controversial. The purpose of the present study was to analyze and compare the long-term neurological recovery following anterior decompression with fusion (ADF) and posterior laminectomy and fusion with bone graft and internal fixation (PLF) based on > ten-year follow-up outcomes in a single centre. Methods. Included in this retrospective cohort study were 48 patients (12 females; mean age 55.79 years (SD 8.94)) who were diagnosed with cervical OPLL, received treatment in our centre, and were followed up for 10.22 to 15.25 years. Of them, 24 patients (six females; mean age 52.88 years (SD 8.79)) received ADF, and the other 24 patients (five females; mean age 56.25 years (SD 9.44)) received PLF. Clinical data including age, sex, and the OPLL canal-occupying ratio were analyzed and compared. The primary outcome was Japanese Orthopaedic Association (JOA) score, and the secondary outcome was visual analogue scale neck pain. Results. Compared with the baseline, neurological function improved significantly after surgery in all patients of both groups (p < 0.001). The JOA recovery rate in the ADF group was significantly higher than that in the PLF group (p < 0.001). There was no significant difference in postoperative cervical pain between the two groups (p = 0.387). The operating time was longer and intraoperative blood loss was greater in the PLF group than the ADF group. More complications were observed in the ADF group than in the PLF group, although the difference was not statistically significant. Conclusion. Long-term neurological function improved significantly after surgery in both groups, with the improvement more pronounced in the ADF group. There was no significant difference in postoperative neck pain between the two groups. The operating time was shorter and intraoperative blood loss was lower in the ADF group; however, the incidence of perioperative complications was higher. Cite this article: Bone Jt Open 2024;5(9):768–775

Ossification of the posterior longitudinal ligament (OPLL) is a condition found predominantly in the oriental population and is rarely seen in non orientals. OPLL can present with cervical canal stenosis and myelopathy (including central cord syndrome), often following minor trauma. Co-existence of OPLL with diffuse idiopathic skeletal hyperostosis (DISH) is a rare condition and very few reports of such patients exist in literature. Here we report the case of a Caucasian with co-existing DISH and OPLL, presenting with acute central cord syndrome associated with fracture of the ossification. A 64 year old Caucasian farmer was transferred to our spinal unit with weakness in the right upper limb following a road traffic accident. On examination he had hyperaesthesia in both upper limbs and motor power of grade 4 in the right upper limb with a distal motor power of grade 3 in the hand. There was no motor deficit in the left upper limb or lower limbs. Radiographs revealed an ossification of the posterior longitudinal ligament with a break at C2 and C3 levels. He also had exuberant soft tissue ossification in the cervical and thoracic spines, suggestive of diffuse idiopathic skeletal hyperostosis (DISH). He recovered completely in 6 weeks with non operative treatment. Fracture of the posterior longitudinal ligament has not been widely reported, although it is possibly more prevalent than is recognised. We report this case in order to highlight the importance of recognising this condition in non oriental populations and to demonstrate that non operative treatment has a good prognosis

In 141 patients with ossification of posterior longitudinal ligament, open-door expansive laminoplasty was done from 1980 to 1998. A follow-up study was made. 10 patients with cervical cord injury and cerebral diseases before or after operation were excluded. 121 of 131 patients were followd directly one to fifteen years(mean: 5 years and 3 months). Subjects included 93 male and 28 female. At the time of operation, their ages ranged from 40 to 80 years(mean:59.5). Operative results were evaluated using the Japanese Orthopaedic Association’s Score(JOA Score) and Hirabayashi’s improvement rate. X-ray was taken to measure the range of cervical spine motion, curvature of the cervical spine and progression of ossified masses. Preoperative JOA scores ranged from 2 to 14 points(mean:9.1), postoperative JOA scores ranged 7 to 17 points(mean:14.1). The mean improvement rate was 62%. The range of cervical spine motion decreased from 26.6 degrees prior to operation to 10.8 degrees after operation. Lordotic curvature also fell from 11.8 degrees before operation to 6.6 degrees after operation. In 20 patients, the postoperative kyphotic curvature increased to 5 degrees of more, although no difference was seen in their improvement rates compared with patients whose lordosis remained unchanged. 80 of 121 patients experienced progression of ossified masses. Three patients underwent additional laminectomy due to progression of ossification or insufficient expansion. Operation took an average 80 minutes and mean amount of blood loss was 215 ml. No patients had postoperative motor paralysis caused by C5 or C6 nerve damage and no serious complications were seen

The August 2014 Spine Roundup. 360 . looks at: rhBMP complicates cervical spine surgery; posterior longitudinal ligament revisited; thoracolumbar posterior instrumentation without fusion in burst fractures; risk modelling for VTE events in spinal surgery; the consequences of dural tears in microdiscectomy; trends in revision spinal surgery; radiofrequency denervation likely effective in facet joint pain and hooks optimally biomechanically transition posterior instrumentation

Background. Microdiscectomy involves substantial aggressive excision of disc material from the intervertebral space to prevent reherniation. However, the recent trend is towards conservative disc removal and simple fragment excision (sequestrectomy). Aim. To compare the clinical outcome of microdiscectomy and sequestrectomy. Methods. During the 2-year study period, we performed 196 lumbar microdiscectomies for disc herniation. One hundred and one patients met the inclusion criteria: unilateral single level lumbar disc herniation. Cases suitable for sequestrectomy were based on intraoperative assessment (stable fibrous ring without significant disc bulge; posterior longitudinal ligament perforation of < 5mm). Results. Five patients were lost to follow-up, 72 patients underwent conventional microdiscectomy and 24 patients were suitable for sequestrectomy and included in the final analysis. There was no significant difference in terms of age and pre-operative VAS in both groups (p >0.05, unpaired t test. In the microdiscectomy group, 17/31 patients with motor deficit and 34/66 patients with sensory deficit showed post-operative improvement, but in sequestrectomy group, only 1 of 5 patients with motor deficit and 8 of 13 with sensory deficit recovered but this was not statistically significant (p>0.05, Fisher's exact test). Conclusion. In the sequestrectomy group, patients had significantly better improvement in VAS score. There was no significant difference between either group with regards to reherniation or post-operative neurological deficit. In a selected group of patients with single level lumbar disc herniation, clinical outcome of sequestrectomy is comparable to conventional microdiscectomy

The evaluation of early results of combined percutaneous pedicle screw fixation and kyphoplasty for the management of thoraco-lumbar burst fractures. Between October 2008 and April 2009, 9 patients with thoracolumbar burst fractures underwent percutaneous short-segment pedicle screw fixation and augmentation kyphoplasty with calcium phosphate cement. All patients were selected according to the type of fracture (unstable type A3 fractures based on the Magerl classification) the absence of neurological signs and an intact posterior longitudinal ligament on the pre-operative MRI scan. Patient demographics, co-morbidities and complications were recorded. The main endpoints included Cobb angle correction, vertebral body height restoration and the length of hospital stay. There were 3 male and 6 female patients with an average age of 43.6 years. The average follow-up was 2.4 months. The mean kyphotic angulation improved from 18.40 pre-operatively to 6, 80 post-operatively. The loss of vertebral body height improved from a mean of 38.7 % pre-operatively to 12.1 % post-operatively. The average duration of surgery was 40 minutes with insignificant blood loss. There were no post-operative complications. The average length of hospital stay was 3.2 days. The combination of percutaneous short-segment pedicle screw fixation supplemented by balloon kypho-plasty for the management of thoracolumbar burst fractures with no neurological deficit offers correction of the normal thoracolumbar anatomy as well as augmentation of the anterior load-bearing column, using a minimally invasive technique. The early results are promising

Vertebral fracture due to a metabolic bone disease or a neoplastic disease is a common and debilitating condition. It most often is associated with either osteoporosis or metastatic bone disease. Some of the patients suffering from such fractures continue to complain of back pain and deformity despite optimal medical therapy, including radiotherapy and biphosphonates. Vertebroplasty, i.e. transcutaneous injection of bone cement into the vertebral body can serve as an internal fixation device and allows restoration of mechanical strength and partial restoration of the vertebral height. During the year 2000, 17 vertebrae in 12 patients were injected. These were either lumbar or thoracic vertebrae. All patients reported decrease in pain and improved ambulation capacity. Two minor complications were encountered including headache lasting for 72 hours prior to spontaneously resolving. This possibly indicates a transarachnoidal approach, the other complication has been cement leak below the posterior longitudinal ligament. The patient reported pain amelioration. No emergency surgical interventions were necessary to date. Treatment of metastatic bone disease should be staged, with only a few vertebrae injected in each session, to prevent pulmonary embolization. Vertebroplasty appears to allow excellent palliative treatment in patients suffering from unresectable primary tumors of the vertebrae, or more commonly, metastatic bone tumors as well as osteoporotic fractures

Awake Rapid Heavy-Weight Closed Reduction (ARHWCR) with weights from 18 to 72 kg was used to reduce six unilateral and nine bilateral cervical facet dislocations. Frankel grading ranged from A to E. Reduction was achieved in all 15 patients with no neurological deterioration. Motor ASIA score improved from a prereduction mean of 64 points to 73 after reduction. Before and after reduction, MRI studies were done on all 15 patients. ARHWCR was done irrespective of the MRI findings. The MRI results were evaluated by five orthopaedic surgeons, five neurosurgeons and five radiologists. The radiologists reported 55% disc herniation in four neurologically-intact patients. On pre-reduction MRI, 34% of anterior longitudinal ligaments and 64% of posterior longitudinal ligaments were reported to be disrupted. They were reported intact on post-reduction MRI. These findings indicate that MRI studies may be open to misinterpretation. Viewing the prereduction MRI, the orthopaedic and neurosurgeons opted for surgical decompression and reduction in 53% of cases. Looking at the post-reduction MRI, they felt that reduction was adequate in 80.6% of cases, but on personal judgment believed that surgical decompression might be of benefit in the remaining 19.4%. ARHWCR is an effective, safe and rapid way of relieving cord compression. Prereduction MRI, irrespective of the patient’s neurological status, is not indicated in acute cervical facet dislocations and can lead to unnecessary surgical intervention

Introduction: Current diagnostic labels used to dictate the prescription of treatment have been derived from studies of cadavers and surgery performed upon the unconscious patient. Methods: In 800 patients, feedback during aware state surgery was independently recorded . Pain sources were detected by spinal probing and verified by endoscopy in the extra foraminal, epidural, foraminal and intradiscal zones. Results: The nerve was found variously painfully tethered to the ascending facet joint, the superior foraminal ligament, superior notch osteophytes, shoulder osteophytes and directly tethered to the disc. In addition, the disc pad, posterior longitudinal ligament and tissues on the dorsum of the vertebra were found to be individually sensitive. These sources produced both local and referred pain. In two thirds of patients with back pain, the disc itself was quiescent to both external and internal manipulation. In a third of patients, the inflamed nerve produced atypical peripheral radicular symptoms on direct probing. Discussion: These unrecognised pain sites and the atypical peripheral symptoms they produce may lead to atypical presentations and mal-targeted interventions. Their persistence may account for failures following conventional surgery. Endoscopy offers an intriguing method of localising and understanding the pathology that underlies diagnostic labels such as failed back syndrome, failed back surgery syndrome, instability and lateral recess stenosis. It is suggested that future surgery be based upon the findings of spinal probing with endoscopic verification. Dynamic retrolisthesis and olisthesis aggravates inflammation in these foraminal sites

Introduction The precise contribution of the posterior longitudinal ligament (PLL) and disc annulus in the burst fracture setting and their potential relative roles during intra operative reduction manoeuvres remains unclear. The anatomical attachments of the posterosuperior fragment most often associated with canal occlusion and potential neurological compromise are not well described in a reproducible model. Methods Burst fractures were induced using a pendulum impact tester. The jig allowed for accurate positioning in all planes and for precise delivery of both the magnitude and vector of the impact force. This allowed for creation of fracture all three major groups of the AO classification. The A3 (burst fracture) was produced in 10 cadaveric sheep spines by delivering a neutral force vector on a physiologically flexed spine. The morphology of the fracture was confirmed by CT. Subsequent laminectomy was performed and the anatomical attachments of the large fragments were identified. Results The PLL was identified following laminectomy in each case. In six of the ten spines there had been significant disruption of the longitudinal structure of the PLL .In a further two cases there had been stripping of the PLL from the posterior aspect of the vertebral body in association with the retropulsed canal fragment. Subsequent excision of the PLL from the posterior aspects of vertebral body and discs did not compromise the attachment of the retropulsed fragment to the disc annulus in any case. Discussion This study confirms the anatomical relationship between disc fragment and disc annulus in the burst fracture setting. The strong attachment between fragment and disc facilitate rotation of the fragment about this hinge and into the canal. Subsequent intraoperative reduction of this fragment by restoration of disc height may require contribution both from this annular attachment and from tension set up in an intact PLL. The relative contributions of each of these structures in the reduction manoeuvre remains unclear

Purpose. Degenerative changes of the lumbar motion segment often lead to stenosis of the spinal canal or neuroforamen. Axial lumbar interbody fusion (AxiaLIF) is intended to indirectly increase and stabilize foraminal dimensions by restoring disc height in patients with degenerative disc disease, thereby relieving axial and radicular pain. Therefore, this study investigated the effects of AxiaLIF on anterior disc height, posterior disc height, foraminal height and foraminal width as well as to determine the effectiveness of this minimally-invasive technique for indirect decompression and restoration of disc height. Method. Eighty-one patients who underwent a 360 degree lumbar interbody fusion at L4-S1 and L5-S1 with AxiaLIF between November 2008 and May 2010 and satisfied all inclusion criteria were included. The preoperative and three-month postoperative digital radiographs were reviewed and analyzed. Disc heights were measured in the planes of the anterior and posterior surfaces of the adjacent vertebral bodies. Foraminal height was measured as the maximum distance between the inferior margin of the pedicle of the superior vertebra and the superior margin of the pedicle of the inferior vertebra. Foraminal width was measured as the shortest distance between the edge of the superior facet of the caudal vertebra and the posterior edge of inferior endplate of the cranial vertebra. Potential magnification error between pre- and post-operative radiographs was corrected using the anterior vertebral height of L5 vertebra. Results. Our study shows that there is a mean increase of 42.0% in posterior disc height (PDH) at L4-5 and 21.5% in anterior disc height (ADH) at L4-5 and PDH mean increase of 33.6% and 16.3% in ADH at L5-S1 in two-level AxiaLIF cases. Similarly the mean change in foraminal height (FH) was 12.6% at L4-5 and 10.8% at L5-S1 in 2-levels AxiaLIF. The mean change in foraminal width (FW) at L4-L5 was 19.9% and 29.1% at L5-S1 in 2-levels AxiaLIF. In the single level AxiaLIF group, the mean change in PDH was 43.1%, the ADH change was 17.5%, the average change in FH was 14.4%, and mean change in FW was 25.3%. The change is reflected as a percentage of the preoperative value. All changes from preoperative to postoperative values were statistically significant. Conclusion. AxiaLIF appears to be an effective minimally invasive device to increase disc height and neuroforaminal area. Our findings appear equivalent to anterior lumbar interbody fusion and transforaminal lumbar interbody fusion in terms of indirect decompression and increase in disc height. This, in combination with the added benefit of preserving the annulus, anterior longitudinal ligament, and posterior longitudinal ligament, suggests the AxiaLIF is an excellent alternative for this patient population. However, additional follow-up studies are necessary to confirm the long-term ability of the implant to maintain fusion and preserve the improvements in disc and foraminal area

Signal intensity changes of the spinal cord on MRI in chronic cervical myelopathy are thought to be indicative of the prognosis. However, the prognostic significance of signal intensity change remains controversial. The purpose of this study was to investigate the characteristics of MR findings in cervical compression myelopathy that reflect the clinical symptoms and the prognosis and to determine the radiographical and clinical factors that correlate to the prognosis. The subjects were 73 patients who underwent cervical expansive laminoplasty. Their mean age was 64 years, and the mean postoperative follow-up was 3.4 years. The pathological conditions were cervical spondylotic myelopathy in 42 and ossification of the posterior longitudinal ligament in 31.MRI (spin-echo sequence) was performed in all patients. Three patterns of spinal cord signal intensity changes on T1-weighted sequences/T2-weighted sequences were detected as follows: normal/ normal. (N/N); normal/ high signal intensity changes (N/Hi); and low signal intensity changes/high signal intensity changes (Lo/Hi). Surgical outcomes were compared among these three groups. The most useful combination of parameters for predicting prognosis was determined. There were 2 patients with N/N, 67 with N/Hi and 4 with Lo/Hi signal change patterns before surgery. Regarding postoperative recovery, the preoperative Lo/Hi group was significantly inferior to the preoperative N/Hi group. The best combination of predictors for surgical outcomes included age, preoperative signal pattern and duration of symptoms. The low signal intensity changes on T1-weighted sequences indicated a poor prognosis. We speculate that high signal intensity changes on T2-weighted images include a broad spectrum of compressive myelomalacid pathologies and reflect a broad spectrum of recuperative potentials of the spinal cord. Predictors for surgical outcomes are preoperative signal intensity change pattern of the spinal cord on radiological evaluations, age at the time of surgery and chronicity of the disease

Objective: This is a prospective study by an independent observer in which outcomes of 118 anterior lumbar interbody fusions (ALIF), done for discogram-concordant axial low back pain, were evaluated. Aims of the study were to assess overall functional and comprehensive outcomes, predictors of outcome, and whether ALIF alone can be recommended for low back pain. Design: The functional and patient perception assessment was based on a self-evaluation back pain questionnaire, which consisted of Oswestry Disability Index, Pain Chart, Numerical Rating Scales (NRS) for back pain and leg pain and SF-36-Version II. The comprehensive outcomes were categorised as satisfactory (excellent, good or improved) and unsatisfactory (fair, poor, unimproved or worse). Results: Overall, we had 61% satisfactory outcomes. Average percentage change in ODI, NRS and SF-36 PCS scores was statistically quite significant. However, patients who had previous posterolateral fusion at the same level had satisfactory outcome in 81%. Incidence of non-union was higher in two-level fusions than one-level fusions, and cases that developed non-unions had unsatisfactory outcome. Conclusions: ALIF alone can be recommended for discogram-concordant axial low back pain. Radiographic evidence of spondylosis, lysis or listhesis, level of fusion, number of levels fused, floating/non-floating type of fusion, and previous back surgery did not affect the outcome. Cases in which the middle column was stabilised (such as those with (a) intervertebral cages extending up to the posterior longitudinal ligament and (b) previous posterolateral fusion at the same level), and hence biomechanically stable, showed better outcomes. Placement of intervertebral implants mainly in the anterior column lead to distraction of the disc anteriorly, resulting in compression of back wall of the disc and facet joints, and narrowing of intervertebral foramina and spinal canal at that level, thus compromising the outcome

The posterior ligament complex (PLC) in the cervical spine comprises the posterior longitudinal ligament, ligamentum flavum and ligamentum nuchae, the latter homologous with the supraspinous and interspinous ligaments at other levels of the spine. In determining instability, evaluation of the PLC is an essential part of the assessment of cervical spine injuries. Disruption of the PLC occurs following flexion injuries, both in compression and in distraction, and following extension injuries with compression. PLC disruption, diagnosed when clinical examination reveals localised posterior spinal tenderness and/or a widened interspinous gap, is confirmed on standard and dynamic flexion-extension radiographs and MRI. This paper is a retrospective review of 162 patients treated for cervical injuries between 1997 and 2001. There were 83 (51%) distraction flexion, 37 (23%) compression flexion, 18 (11%) compression extension, 17 (10%) vertical compression, six (4%) distraction extension and one (1%) lateral flexion injuries. In 79 patients with pure ligamentous instability, an interspinous stabilisation procedure was performed, using a titanium cable. When associated fractures occurred with PLC disruption, neurologically intact patients were managed conservatively with traction followed by a spinal brace. Patients with a neurological deficit underwent surgery. Using delayed dynamic flexion-extension views and MRI, PLC disruption was diagnosed late in nine flexion distraction injuries without facet dislocation. At follow-up, flexion-extension views showed that all PLC disruptions with associated fractures had stabilised. There were two broken cables in patients who underwent surgery. Patients with cervical instability following trauma may be treated non-operatively when there are associated fractures, while patients with pure ligamentous instability should undergo fusion. Further, to exclude occult PLC disruption, all cervical injuries should be reviewed on flexion-extension views once the paraspinal muscle spasm has settled

The accuracy of pedicle screw placement is essential for successful spinal reconstructive surgery. The authors of several previous studies have described the use of image-based navigational templates for pedicle screw placement. These are designed based on a pre-operative computed tomographic (CT) image that fits into a unique position on an individual's bone, and holes are carefully designed to guide the drill or the pedicle probe through a pre-planned trajectory. The current study was conducted to optimise navigational template design and establish its designing method for safe and accurate pedicle screw placement. Thin-section CT scans were obtained from 10 spine surgery patients including 7 patients with adolescent idiopathic scoliosis (AIS) and three with thoracic ossification of the posterior longitudinal ligament (OPLL). The CT image data were transferred to the commercially available image-processing software and were used to reconstruct a three-dimensional (3D) model of the bony structures and plan pedicle screw placement. These data were transferred to the 3D-CAD software for the design of the template. Care was taken in designing the template so that the best intraoperative handling would be achieved by choosing several round contact surfaces on the visualised posterior vertebral bony structure, such as transverse process, spinous process and lamina. These contact surfaces and holes to guide the drill or the pedicle probe were then connected by a curved pipe. STL format files for the bony models with planned pedicle screw holes and individual templates were prepared for rapid prototype fabrication of the physical models. The bony models were made using gypsum-based 3D printer and individual templates were fabricated by a selective laser melting machine using commercially pure titanium powder. Pedicle screw trajectory of the bony model, adaptation and stability of the template on the bony model, and screw hole orientation of the template were evaluated using physical models. Custom-made titanium templates with adequate adaptation and stability in addition to proper orientation of the screw holes were sterilised by autoclave and evaluated during surgery. During segmentation, reproducibility of transverse and spinous processes were inferior to the lamina and considered inadequate to select as contact surfaces. A template design with more bone contact area might enhance the stability of the template on the bone but it is susceptible to intervening soft tissue and geometric inaccuracy of the template. In the bony model evaluation, the stability and adaptation of the templates were sufficient with few small round contact surfaces on each lamina; thus, a large contact surface was not necessary. In clinical patients, proper fit for positioning the template was easily found manually during the operation and 141/142 screws were inserted accurately with 1 insignificant pedicle wall breach in AIS patient. This study provides a useful design concept for the development and introduction of custom-fit navigational template for placing pedicle screws easily and safely

The thoracoscopic technic is a minimal surgical approach that minimizes the skin, muscle and ribs trauma without altering the effectiveness of the treatment. This type of surgery has been gaining importance due to its advantages: excellent lighting, visualization and magnification. It offers an acute visual control during manipulation and dissection of delicate structures. We aim to assess the anterior release and the thoracic spine arthrodesis through thoracoscopic approach and measure the effectiveness and security of anterior thoracoscopic instrumentation in an experimental study in pigs. The study was performed on 18 pigs which weighed between 40 and 60 kg. The surgical procedures were conducted at the Hospital Italiano in Buenos Aires. A thoracoscopic surgery was performed as an access to the spine. The quality of the anterior release ranged significantly from cases in which the incision of the common anterior vertebral ligament could not be finished to cases in which more than 75% of the anterolateral disk circumference was released. In the subjective thoracoscopic assessment of the surgeon the screws were placed successfully in all The radiographic assessment confirmed the surgeon’s presumption, all the screws had been placed correctly. The rod presented complications in several cases. The radiographic assessment showed that 40.6% (13 patients) of the disc spaces were pseudoarthrosic or with a delayed union. The macroscopic examination confirmed this finding and raised the number of pseudoarthrosic spaces up to 46.8% (15 patients) revealing 4 discs that still had a nucleus pulposus. The data were reinforced by histologic examination. This histologic cuts were performed using the E & O method. The fibrous ring was clearly identified in the pseudoarthrosic cases as well as the processes of the osteochondral bone formation in its different phases of maturation. It is very important to highlight that in our experience we had found a direct relationship between the quality of the disectomy, the fusion technique and the experience of the surgeon. The surgical technique, the rod placement on the screws needs proper positioning and depth. The radiographic and microscopic examination confirmed that the posterior longitudinal ligaments was not damaged. The thoracoscopic instrumentations in pigs using a rod and screws of third generation is a secure technique. It is essential the development of instrumentation which allows effective thoracoscopic distraction and compression

Introduction: The clinical condition was described as Ankylosing Hyperostosis of the Spine by Forestier (1950. 1. ), was expanded by Resnick (1975) with the Extraspinal Manifestations. 2. What is the nature of this unique formation, asymptomatic in 90% of cases? Several researchers questioned whether the hyperostosis was physiological or pathological. Initially, in 1985 B.M. Rotschild called it a phenomenon . 3. Schlapbach in 1989 found no associated pathological condition . 4. Hutton in his Editorial “Hyperostosis…a State not a Disease“ was doubtful . 5. . In recent personal observations, protection by ossification was recorded in a severe trauma case and in vertebrae weakened by malignant infiltration. Methods: A phylogenetic review of the animal world, followed by an ontogenetic study of mammals/ humans, could assist in a decision regarding the nature (physio-or pathological) of the hyperostosis. Results: The phylogenetic lineage on one side showed the oldest record of hyperostosis in dinosaur (144 million years ago=mya). Ossifications were found in the anterior, lateral, posterior longitudinal ligaments, in C1–C2 transverse ligament. In the other phylogenetic, Hyperostosis was in historic and contemporary mammals. The next step in this study is in the ontogenetic line of the Humans. The oldest skeleton (Ethiopia, 4.5 mya) showed “bridged vertebrae“. The first definite hyperostosis was in the Shanidar skeleton (Iraq, 40–12,000 BCE) with“flowing osteophytes”. In the historic Humans since 9500 BCE, hyperostosis was found in Europeans, Egyptians, Indians (Chile) and Incas. In the Christian era, hyperostosis was present in Roman-British/ Celt populations, Franks, Saxons, British, Swiss and N. Americans. In the 20th C, it is pandemic. Discussion: a. Impressions from the animal world: Paleopathology was established as a scientific branch in 1912 (Ruffer), and exemplified its value in understanding the nature of diseases. Moodie questioned the function of the long spinal “bony rods”, considered them with a protective function. Others . 6. suggested spinal hyperostosis as induced by “mechanical stress”. Shore. 7. (1936) described the spondylitis ossificans ligamentorum as due to mechanical strain. b. Impressions from the Hominid world: The ontogenetic line shows a constant presence of hyperostosis in prehistoric and historic periods. Parallel to human migration from Africa, hyperostosis expanded globally. c. The theory of logical probability: It is postulated that hyperostosis is a condition, as no pathology (other than inflammatory) could have expanded and persisted in many species along millions of years, as it would have been removed by the rules of the Darwinian Selection. Possibly triggered by strain in younger age, functional in the past, it is today an atavistic older age “condition“, with increased osteoblastic activity in connective tissues of ligaments and tendons. At times it is incidentally discovered and is occasionally excessive. Once presented with clinical manifestations, it becomes defined an illness and should be called the Forestier-Resnick syndrome

INTRODUCTION: The clinical condition was described as Ankylosing Hyperostosis of the Spine by Forestier (1950. 1. ), was expanded by Resnick (1975) with the Extraspinal Manifestations. 2. What is the nature of this unique formation, asymptomatic in 90% of cases? Several researchers questioned whether the hyperostosis was physiological or pathological. Initially, in 1985 B.M. Rotschild called it a phenomenon. 3. Schlapbach in 1989 found no associated pathological condition. 4. Hutton in his Editorial “Hyperostosis…a State not a Disease“ was doubtful. 5. . In recent personal observations, protection by ossification was recorded in a severe trauma case and in vertebrae weakened by malignant infiltration. METHODS: A phylogenetic review of the animal world, followed by an ontogenetic study of mammals/ humans, could assist in a decision regarding the nature (physio-or pathological) of the hyperostosis. RESULTS: The phylogenetic lineage on one side showed the oldest record of hyperostosis in dinosaur (144 million years ago=mya). Ossifications were found in the anterior, lateral, posterior longitudinal ligaments, in C1-C2 transverse ligament. In the other phylogenetic, Hyperostosis was in historic and contemporary mammals. The next step in this study is in the ontogenetic line of the Humans. The oldest skeleton (Ethiopia, 4.5 mya) showed “bridged vertebrae“. The first definite hyperostosis was in the Shanidar skeleton (Iraq, 40–12,000 BCE) with “flowing osteophytes”. In the historic Humans since 9500 BCE, hyperostosis was found in Europeans, Egyptians, Indians (Chile) and Incas. In the Christian era, hyperostosis was present in Roman-British/Celt populations, Franks, Saxons, British, Swiss and N. Americans. In the 20th C, it is pandemic. DISCUSSION: (a) . Impressions from the animal world. : Paleo-pathology was established as a scientific branch in 1912 (Ruffer), and exemplified its value in understanding the nature of diseases. Moodie questioned the function of the long spinal “bony rods”, considered them with a protective function. Others. 6. suggested spinal hyperostosis as induced by “mechanical stress”. Shore. 7. (1936) described the spondylitis ossificans ligamentorum as due to mechanical strain. (b . Impressions from the Hominid world. : The ontogenetic line shows a constant presence of hyperostosis in prehistoric and historic periods. Parallel to human migration from Africa, hyperostosis expanded globally. (c) . The theory of logical probability. : It is postulated that hyperostosis is a condition, as no pathology (other than inflammatory) could have expanded and persisted in many species along millions of years, as it would have been removed by the rules of the Darwinian Selection. Possibly triggered by strain in younger age, functional in the past, it is today an atavistic older age “condition“, with increased osteoblastic activity in connective tissues of ligaments and tendons. At times it is incidentally discovered and is occasionally excessive. Once presented with clinical manifestations, it becomes defined an illness and should be called the Forestier-Resnick syndrome

Introduction: Spinal cord injury (SCI) continues to challenge the healthcare and the adjunct social welfare systems. Significant advances have been made in our understanding of the pathological cascade following the initial insult. However, this has yet to be translated into clinically significant treatments and one possible reason for this is that little is known about the actual interaction between the cord and the spinal column at the moment of impact; a factor that is becoming increasingly recognised as important. Burst fractures are a common cause of SCI and are sufficiently well defined to allow significant advances to be made in developing laboratory models of the fracture process. Following on from these advances an in-vitro model of the interaction between the cord and burst fracture fragment was developed and used to perform preliminary experiments to establish those factors that are important in determining the extent of probable cord damage. Methods: A rig was developed that reliably reproduced a range of fragment-cord impact scenarios previously observed in the development of a model of the burst fracture process. In summary, a simulated bone fragment of mass 7.2 g was fired, transversely, at explanted bovine cord (within 3 hours of slaughter) with a velocity of 2.5, 5.0 or 7.5 ms-1. The cords were mounted in a tensile testing machine using a novel clamping system and held at 8 % strain. A surrogate posterior longitudinal ligament (PLL) was included and simulated in three biomechanically relevant conditions: absent, 0 % strain and 14 % strain. The posterior elements were represented by an anatomically correct surrogate. The impacts were recorded by using either a high speed video camera (4500 frames/s) or a series of fine pressure transducers. Results: The fragments were recorded to undergo the same occlusion profile as previously reported in the burst fracture model, except that the cord itself reduced the level of maximum occlusion possible. All tests displayed the fragment recoiling following maximum occlusion. The maximum occlusion and the time to this position were found to be significantly dependent on both the fragment velocity and the condition of the PLL. Similar results were observed for peak pressure. One surprising result was that maximum occlusion or time to this event did not change with or without the cord being encased in the dura mater; a structure that is thought to protect the cord from external impacts. Discussion: The model developed here of the cord-column interaction for the burst fracture produced useful initial insights into the factors that affect the impact on the cord. The PLL has a significant role to play in both reducing the peak pressures and the spreading the energy imparted over a longer period. The model has several areas in which it could be improved and these include 1) the incorporation of the perfusion pressure which tends to hydraulically stiffen the cord and 2) the inclusion of the cerebrospinal fluid, which may operate in unison with the dura in protecting the cord from impacts. Future work includes the incorporation of the CSF into the model, the development of surrogate cords and the generation of computational models using novel programming techniques

Introduction The early clinical results of cervical disc replacement surgery are encouraging but the in vivo kinematics of prostheses remains poorly understood. Two recent published reports suggest that use of a prosthesis with an unconstrained (over normal range of motion) biconvex nucleus (Bryan Cervical Disc® – Medtronic Sofamor Danek, Memphis, TN) can be associated with post-operative segmental kyphosis. This study examines post-operative kyphosis and segmental imbalance following cervical disc replacement using the Bryan Cervical Disc prosthesis and factors which may influence this. In particular, the influence of change in disc space height as a result of surgery was studied. Methods 67 patients underwent prosthetic disc replacement by one of three surgeons (19, 25 and 23 patients, respectively) using the Bryan prosthesis. 46 single, 20 double and 1 triple level were operated. Neutral pre- and post-op erect and intra-operative x-rays were examined manually and using digital image analysis software (Medical Metrics, Inc. Houston, TX). Possible contributing factors to segmental alignment were studied including: pre-op alignment, angle of prosthesis insertion, disc space degeneration and sacrifice of the posterior longitudinal ligament (PLL). Particular attention was given to changes in disc space height and factors which may influence this. Inter- and intra-observer agreement was assessed. Non-parametric tests were used for assessment of categorical and skewed continuous variables. Multivariate linear regression was used to adjust significant correlation coefficients. Significance was set at p< 0.05. Results The median pre-op focal lordosis of +0.5° (range: 21 to −14°, −ve = kyphotic) changed by −1° (+14 to −17°), to post-op: 0° (+11.5 to −16°). There was a significant difference in the median change in focal lordosis for surgeon 1 (−3°) vs. surgeons 2 & 3 (−1°) (p< 0.005) and in the loss of disc space height. Median loss of disc space height for surgeon 1 was 22% vs. 8% for surgeons 2 & 3 (p< 0.002). Correlation co-efficient (Spearman) for change in disc space height vs. change in disc space angulation was 0.67 (p< 0.0001). No single pre- or intra-operative factor was found to clearly correlate with subsequent loss of disc space height apart from a trend towards a weak correlation with the angle of prosthesis insertion (r=0.24, p=0.06). Discussion The median change (loss) in focal lordosis was −1.5° but there was considerable range: from +14° to −17°. Attempts to identify contributing factors suggest that a number may be involved but there did appear to be a highly significant correlation between loss of disc space height following surgery and subsequent focal kyphosis. While the difference in outcomes between Surgeon 1 and Surgeons 2 & 3 is probably not clinically significant, it does suggest that intra-operative factors such as the angle of prosthesis insertion may be important. We are continuing to study these factors