Use Of Spinal Instrumentation Research Articles

Operační léčba tuberkulózní spondylodiscitidy

PURPOSE OF THE STUDY The paper presents a monocentric retrospective study of patients treated surgically for spinal tuberculosis. Clinical and radiological results are analysed, early and late complications are recorded. The study aims to answer the following questions. 1. Can we use instrumentation to restore the stability and alignment in the infected spinal focus? 2. Should we always perform radical anterior resection of TBC lesions? 3. What is the prognosis of surgical treatment of TBC patients with neurological deficit manifestation? MATERIAL AND METHODS Between 2010 and 2020, a total of 12 patients were treated for spinal tuberculosis at our department, of whom 9 patients (5 men, 4 women) with the mean age of 47.3 years (range 29 to 83 years) underwent a surgery. A total of three patients were operated on before the final confirmation of the TBC and treatment with antituberculosis medication, four patients in the initial therapy phase and two patients in the continuous phase. Two patients only underwent a non-instrumented decompression surgery followed by external support fixation. In the other seven patients, always with spinal deformity, instrumentation was used (3 cases of isolated posterior decompression, transpedicular fixation, posterior fusion, 4 cases of anteroposterior instrumented reconstruction). In 2 cases a structural bone graft and in 2 cases an expandable titanium cage were used for anterior column reconstruction. RESULTS Of the total number of patients, altogether eight patients were assessed at 1 year after surgery (one 83-year-old patient died from heart failure 4 months after surgery). Of the remaining eight patients, three patients exhibited a neurological deficit and postoperative regression of the finding. The McCormick score improved from the preoperative mean score of 3.25 to 1.62 at 1 year after surgery (p < 0.001). The clinical VAS score regressed from 5.75 to 1.63 at 1 year after surgery (p < 0.001). Radiographic healing of the anterior fusion was achieved in all patients, both after decompression and instrumented surgery. The initial mean kyphosis of 20.36 degrees of the operated segment measured by the mCobb angle was corrected to 14.6 degrees postoperatively, with a subsequent slight deterioration to 14.86 degrees (p < 0.05). The greatest correction was achieved in patients who had undergone a two-stage surgery with anterior resection and AP reconstruction. DISCUSSION In our cohort, titanium instrumentation was used in seven of nine patients. One patient only manifested persistent tuberculosis with nonspecific bacterial flora superinfection. Revision surgery with anterior radical debridement and subsequent treatment with antituberculotic drugs healed the patient. There were four patients with major preoperative neurological deficit persisting more than 2 weeks before the final treatment with subsequent improvement in all cases. These patients were treated with anteroposterior reconstruction and anterior radical debridement. CONCLUSIONS No increased risk of recurrent infection associated with the use of spinal instrumentation was found in the study. Anterior radical debridement is performed in patients with manifested kyphotic deformity and spinal canal compression, followed by reconstruction with a structural bone graft or a titanium cage. The other patients are treated based on the principle of "optimal" debridement with or without the use of transpedicular instrumentation. If adequate spinal canal decompression and stability are achieved, neurological improvement can be anticipated even in case of a major neurological deficit. Key words: spine tuberculosis, tuberculous spondylitis, Pott's disease, anterior debridement, spine instrumentation.

Osteoconductivity and neurotoxicity of silver-containing hydroxyapatite coating cage for spinal interbody fusion in rats.

The use of spinal instrumentation is an established risk factor for postoperative infection. To address this problem, we prepared silver-containing hydroxyapatite coating, consisting of highly osteoconductive hydroxyapatite interfused with silver. The technology has been adopted for total hip arthroplasty. Silver-containing hydroxyapatite coating has been reported to have good biocompatibility and low toxicity. However, no studies about applying this coating in spinal surgery have addressed the osteoconductivity and direct neurotoxicity to the spinal cord of silver-containing hydroxyapatite cages in spinal interbody fusion. In this study, we evaluated the osteoconductivity and neurotoxicity of silver-containing hydroxyapatite-coated implants in rats. Titanium (non-coated, hydroxyapatite-coated, and silver-containing hydroxyapatite-coated) interbody cages were inserted into the spine for anterior lumbar fusion. At 8 weeks postoperatively, micro-computed tomography and histology were performed to evaluate the osteoconductivity of the cage. Inclined plane test and toe pinch test were performed postoperatively to assess neurotoxicity. Micro-computed tomography data indicated no significant difference in bone volume/total volume among the three groups. Histologically, the hydroxyapatite-coated and silver-containing hydroxyapatite-coated groups showed significantly higher bone contact rate than that of the titanium group. In contrast, there was no significant difference in bone formation rate among the three groups. Data of inclined plane and toe pinch test showed no significant loss of motor and sensory function in the three groups. Furthermore, there was no degeneration, necrosis, or accumulation of silver in the spinal cord on histology. This study suggests that silver-hydroxyapatite-coated interbody cages produce good osteoconductivity and are not associated with direct neurotoxicity.

The clinical utility of the Spinal Instability Neoplastic Score (SINS) system in spinal epidural metastases: a retrospective study.

A retrospective study. This study assessed the clinical utility of the Spinal Instability Neoplastic Score (SINS) in relation to the surgical treatment of spinal epidural metastasis and factors important for surgical decision-making. These factors include epidural spinal cord compression (ESCC), patient prognosis and neurologic status. Queen Elizabeth II Health Sciences Centre, Halifax, Canada. We identified 285 patients with spinal metastatic disease. Data were extracted through a retrospective review. SINS and ESCC were scored based on CT and MRI, respectively. Patients were grouped into stable (35%), potentially unstable (52%), and unstable (13%) groups. The overall incidence of metastatic spinal deformity was 9%. Surgical interventions were performed in 21% of patients, including decompression and instrumented fusion (70%), decompression alone (17%), percutaneous vertebral augmentation (9%), and instrumented vertebral augmentation (5%). The use of spinal instrumentation was significantly associated with unstable SINS (p = 0.005). Grade 3 ESCC was also significantly associated with unstable SINS (p < 0.001). Kaplan-Meier analysis revealed that SINS was not a predictor of survival (p = 0.98). In the radiotherapy-alone group, a significant proportion of patients with potentially unstable SINS (30%) progressed into unstable SINS category at an average 364 ± 244 days (p < 0.001). This study demonstrated that more severe categories of SINS were associated with higher degrees of ESCC, and surgical interventions were more often utilized in this group with more frequent placement of spinal instrumentation. Although SINS did not predict patient prognosis, it correlates with the progression of metastatic instability in patients treated with radiotherapy.

Effective Protocol to Treat Patients with Deep Wound Infection after Spinal Lumbar Fusion

Introduction Deep wound infection (DWI) is a complication associated with poorer outcome and increased costs. The DWI rates increased in the last decade especially because of the use of spinal instrumentation. Although this condition is important for the surgical outcome, there is still no agreement about the about the need to remove the instrumentation. The objective is to describe the authors' experience in managing DWI without the removal of instrumentation after performing a procedure on the lumbar spine and the clinical and functional long-term course of these patients. Patients and Methods A prospective cohort study with the patients who presented deep infection of the surgical wound. All the patients with a clinical suspicion of this complication were submitted to an aggressive protocol of wound opening, collection of material for a microbiological examination, exhaustive washing, debridement, implementation of a continuous washing system, primary suturing of the wound, and treatment with antibiotics IV and then orally. The instrumentation was not removed from any patient. The patients were evaluated radiologically, clinically, functionally, and by blood test examination, white blood cell count, erythrocyte sedimentation rate, and C-reactive protein, during the follow-up. Paired analyses were performed using the Wilcoxon test to evaluate changes in the instrument scores. Results The mean age was 59.31 ( ± 13.17) and most of the patients were female (94.7%; 18/19). At least one comorbidity was observed in 68.4% of the patients, the most frequent being obesity, present in 26.3% of the patients. The mean period for the identification of DWI was 2 weeks and 57.9% underwent only one wound exploration. Staphylococcus aureus was the most common microorganisms ( n = 13 cases, 68.4%). Blood tests showed a significant decrease of the WBC, ESR, and CRP 6 weeks' posttreatment when compared with pretreatment values. Comparing the 6 weeks' posttreatment evaluation and the final evaluation, a significant reduction of ESR and CRP was also observed. Conclusion Patients with DWI after posterior lumbar spinal instrumentation fusion can be treated without removal of the instrumentation through an aggressive protocol of wound exploration, extensive washing, debridement of necrotic tissue, closed irrigation system during 5 days, and proper antibiotic therapy. The WBC, ESR, and CRP blood tests were not useful to predict the need for surgical reinterventions. Despite the complication, the patients presented improvement with respect to pain, functional capacity, and preoperative quality of life.

Image-Guided Spinal Navigation for C1-C2 Instrumentation: Part I.

Disorders of the spine are one of the oldest known human maladies, with descriptions found in ancient medical literature. As in many other areas of medicine, treatment of patients with these disorders has undergone rapid progress over the last century. Among treatment modalities, spinal instrumentation has been a significant technical advancement. Increased use of spinal instrumentation has spurred the need for accurate positioning of screws/instrumentation and enhanced stability of the construct. Traditionally, these have been placed using anatomic landmarks and intraoperative fluoroscopy. In patients with advanced degenerative disease or trauma, or in those with severe curvature deformity, anatomy can be of limited help. With intraoperative fluoroscopy, limited visualization can be a significant issue, especially in patients with a large body habitus. Image guidance, by providing live, accurate information for placement of instrumentation, significantly improves upon these issues. Image guidance has been used in neurologic surgery during recent decades. It was employed initially for intracranial applications, including treatment of brain disorders, with significant benefits and is now used routinely as an important adjunct tool in the operating room for intracranial neurologic surgery. Only more recently has image guidance been used in spine surgery.

Vertebral body reconstruction using antibiotic impregnated bone cement (PMMA) in osteomyelitis of lumbar spine: Case reports

Osteomyelitis has long been one of the most common, difficult and challenging problem confronted by the surgeons in daily practice. The key to successful management is early diagnosis and appropriate treatment. The first line in treatment of vertebral osteomyelitis is conservative. There is an increased risk of deep infection with the use of spinal instrumentation. Therefore, the placement of implants in an infected area remains a matter of debate. We present two patients with lumbar vertebral osteomyelitis using antibiotic impregnated PMMA for vertebral body reconstruction and pedicle screw fixation. Post-operative follow-up showed satisfactory results both symptomatically and neurologically. The antibiotic impregnated bone cement acts as both interbody spacer and an antibiotic carrier. However, long term outcomes in both the cases requires further evaluation.

The Postoperative Spine

Potential complications following spinal surgery include neural compression due to hematoma, recurrent disk herniation, epidural fibrosis, dural tear with pseudomeningocele formation, and infection. Specific complications relate to the use of spinal instrumentation that include incorrectly positioned instrumentation and failure of spinal fusion leading to instrumentation loosening or breakage. To interpret the postoperative imaging correctly, it is necessary to understand the nature of the surgical procedure that has been performed and the normal postoperative appearances. Magnetic resonance imaging is the mainstay in the evaluation of the postoperative spine. Radiographs and computed tomography continue to have a major role in assessing fusion and in the assessment of complications related to instrumentation.

Spontaneous spinal epidural abscess in patients 50 years of age and older: a 15-year institutional perspective and review of the literature

A spinal epidural abscess (SEA) is a rare but severe infection requiring prompt recognition and management. The incidence of SEA has doubled in the past decade, owing to an aging population and to increased use of spinal instrumentation and vascular access. The optimal management of SEAs in patients 50 years of age and older remains a matter of considerable debate. In an older patient population with multiple comorbidities, whether intravenous antibiotics alone or in combination with surgery lead to superior outcomes remains unknown. The present study retrospectively analyzes cases of SEAs, in patients 50 years of age and older, treated at Duke University Medical Center over the past 15 years. Eighty-two patients underwent treatment for a spinal epidural abscess between 1999 and 2013. There were 46 men and 36 women, whose overall mean age (± SD) was 65 ± 8.58 years (range 50-82 years). The mean duration of clinical follow-up was 41.38 ± 86.48 weeks. Thirty patients (37%) underwent surgery for removal of the abscess, whereas 52 (63%) were treated more conservatively, undergoing CT-guided aspiration or receiving antibiotics alone based on the results of blood cultures. The correlation between pretreatment variables and outcomes was evaluated in a multivariate regression analysis. Back pain and severe motor deficits were the most common presenting symptoms. Compared with baseline neurological status, the majority of patients (68%) reported being neurologically "better" or "unchanged." Twelve patients (15%) had a good outcome (7 [23%] treated operatively vs 5 [10%] treated nonoperatively, p = 0.03), while clinical status in 41 patients (50%) remained unchanged (10 [33%] treated operatively vs 31 [60%] treated nonoperatively, p = 0.01). Overall, 20 patients (25%) died (9 [30%] treated operatively vs 11 [21%] treated nonoperatively, p = 0.43). In a multivariate logistic regression model, an increasing baseline level of pain, the presence of paraplegia or quadriplegia on initial presentation, and a dorsally located SEA were independently associated with poor outcomes. The results of the study suggest that in patients 50 years of age and older, early surgical decompression combined with intravenous antimicrobial therapy was not associated with superior clinical outcomes when compared with intravenous antimicrobial therapy alone.

Pedicle Subtraction Osteotomy in the Cervical Spine

Description of surgical technique with review of literature. To describe the surgical management of cervical spine deformity, using pedicle subtraction osteotomy. Previous articles have primarily described Smith-Petersen osteotomies and Simmons' modifications to correct fixed cervical deformity. Those were typically performed with the patient awake and sedated in a seated position and without the use of spinal instrumentation. Description of a single surgeon's technique for performing pedicle subtraction osteotomy to treat fixed cervical deformity. The use of pedicle subtraction osteotomy in the cervical spine is a safe and effective procedure when performed by experienced surgeons and can result in a satisfying outcome for both the patient and the surgeon.

Infections in spinal instrumentation

Surgical-site infection (SSI) in the spine is a serious postoperative complication. Factors such as posterior surgical approach, arthrodesis, use of spinal instrumentation, age, obesity, diabetes, tobacco use, operating-room environment and estimated blood loss are well established in the literature to affect the risk of infection. Infection after spine surgery with instrumentation is becoming a common pathology. The reported infection rates range from 0.7% to 11.9%, depending on the diagnosis and complexity of the procedure. Besides operative factors, patient characteristics could also account for increased infection rates. These infections after instrumented spinal fusion are particularly difficult to manage due to the implanted, and possibly infected, instrumentation. Because the medical, economic and social costs of SSI after spinal instrumentation are enormous, any significant reduction in risks will pay dividends. The goal of this literature review was to analyse risk factors, causative organisms, diagnostic elements (both clinical and biological), different treatment options and their efficiency and consequences and the means of SSI prevention.

Risk Factors for Postoperative Infection Following Posterior Lumbar Instrumented Arthrodesis

Surgical site infection in the spine is a serious postoperative complication. Factors such as posterior surgical approach, arthrodesis, use of spinal instrumentation, age, obesity, diabetes, tobacco use, operating-room environment, and estimated blood loss are well established in the literature to affect the risk of infection. The goal of this study was to analyze and identify independent risk factors for surgical site infection among spine patients undergoing posterior lumbar instrumented arthrodesis. The medical records of 3218 patients who underwent posterior lumbar instrumented arthrodesis from January 2000 to December 2006 were reviewed to identify those who developed a postoperative infection (eighty-four patients; 2.6%). The size of this single-institution patient group allowed construction of a multivariate logistic regression model to evaluate the independent associations of potential risk factors for surgical site infection in the spine. In the final regression model, obesity, estimated intraoperative blood loss, ten or more people in the operating room, a dural tear, history of diabetes, chronic obstructive pulmonary disease, coronary heart disease, and osteoporosis were critical risk factors for the onset of spinal surgical site infection. Obesity and a history of chronic obstructive pulmonary disease were the strongest risk factors for postoperative spinal infection after adjusting for all other variables. The most common pathogen was methicillin-resistant Staphylococcus aureus with a prevalence of 34.5%. This study established a single institution infection rate for posterior lumbar instrumented arthrodesis at 2.6%. This analysis confirms previously demonstrated risk factors for postoperative infection while reporting on new potential independent risk factors of osteoporosis, chronic obstructive pulmonary disease, and dural tears in the setting of posterior lumbar instrumented arthrodesis. Areas of new research can focus on the roles these novel factors may play in the pathogenesis of surgical site infections in the spine.

Perioperative complications and adverse events after lumbar spinal surgery: evaluation of 1012 operations at a single center

BackgroundLumbar surgery and associated complications are increasing as society is aging. However, definitions of complications after lumbar surgery have not been established and previous reports have varied in the definition of, and focus on, intraoperative or major postoperative complications. We analyzed the frequency and severity of perioperative complications and all minor adverse events in lumbar surgery at a single center. MethodsWe retrospectively reviewed all lumbar surgery, including decompression surgery with or without fusion, at Meijo Hospital over a 10-year period. Perioperative complications and all surgery-related adverse events until 1 month postoperatively were reviewed for 1012 operations on 918 patients (average age 54 years old). The incidence of intraoperative complications was compared between junior (<10 years experience of spine surgery) and senior (≥10 years experience) surgeons. ResultsPerioperative complications and adverse events occurred in 159 operations (15.7%) on 127 patients (13.8%). There were a variety of perioperative adverse events, including digestive problems. Of the 159 complications and events, 24 (2.4%) were intraoperative and 135 (13.3%) were postoperative. Incidence of intraoperative complications was not significantly higher for junior surgeons; however, the operations performed by senior surgeons were significantly more invasive. Complications were more frequent in elderly patients (p < 0.01) and in operations that were longer (p < 0.0001), had greater estimated blood loss (p < 0.0001), and involved use of spinal instrumentation (p < 0.0001). Psychotic symptoms occurred significantly more often in older patients (p < 0.001). ConclusionThe absence of a relationship between the experience of the surgeon and incidence of intraoperative complications may be because of the greater effect of invasive surgery. Although age and invasiveness were associated with more perioperative adverse events, we do not conclude that major surgery should be avoided for elderly patients. In contrast, careful focus on the surgical indication and procedure is required for these patients.

Closed Suction Irrigation for the Treatment of Postoperative Wound Infections Following Posterior Spinal Fusion and Instrumentation

Retrospective review of clinical cases. This study describes the success rate of closed suction irrigation system (CSIS) in the treatment of post operative spinal infections. Given the widening use of spinal instrumentation, the management of related postoperative deep wound infections has become increasingly important. In the literature, there have been reports of several treatment methods yet no firmly established protocol for management of postoperative deep wound infections exists. The goal of this study was to determine the effectiveness of our protocol employing (CSIS) in the treatment of postoperative deep wound infections. A retrospective record review of 500 posterior instrumented fusions between 1990 and 2002. Twenty-eight consecutive infections (5%) were diagnosed and treated by a standardized treatment protocol of Incision and Drainage, and CSIS. Cultures were obtained, wounds closed primarily, and appropriate intravenous antibiotic treatments initiated. For statistical evaluation, patients were assigned a risk factor (RF) described by Levi et al (J Neurosurg. 1997;86:975-980). Point values were assigned to medical comorbidities that may contribute to postoperative infection risk; higher RF values indicate an increased risk. Twenty-one acute and 7 late (>6 months) infections were followed for 22.3 months (1-86 months), post-CSIS treatment. Twenty-one (75%) resolved without recurrence with one CSIS treatment. Seven acute infections (25%) required a second course of treatment. Hospitalization for the index procedure averaged 15.4 days; 28.9 days for reinfections. No patient with an acute infection required implant removal. The reinfection group had higher blood loss, more levels fused, and longer hospitalization. The reinfection group was comprised entirely of pediatric patients. No correlation was found between RF values and greater risk of recurrent infection. Removal of implants is unnecessary in acute infections, provided the infection does not return. CSIS is an effective method for treatment of postoperative wound infections following instrumented spinal fusion avoiding the need for secondary closure.

Surgical treatment of metastatic vertebral tumors.

Surgical treatment of metastatic spinal cord compression is controversial. The purpose of this study was to investigate the effectiveness of our current surgical treatments and the use of spinal instrumentation. In this retrospective study covering the years between 1990 and 2006, 100 patients with spinal metastases which were secondary to various cancers underwent posterior and/or anterior decompression with spinal stabilization for the purposes of reduction of pain, and/or to help correct or improve neurological deficits. The group was made up of 60 men and 40 women whose ages ranged from 16 to 83 years (average of 60 years), and the average follow-up period was 14 months. The effect of treatment upon pain relief and neural deficits was assessed, and the cumulative survival rate was calculated by the Kaplan-Meier method. The average surgical time was 185 min. This was calculated based on the following times, listed here with the surgery type: 178 min for posterior surgery; 245 min for anterior surgery;465 min for combined surgery;and 475 min for total en bloc spondylectomy. Average blood loss during surgery was 1,630 ml for posterior surgery, 1,760 ml for anterior surgery, 1,930 ml for combined surgery, and 3,640 ml for total en bloc spondylectomy. Preoperative pain and paralysis were improved by 88% and 53%, respectively. In regards to surgical complications, postoperative epidural hematoma was observed in 2 patients, and instrumentation-related infection was observed in 1. Only 2 patients died within 2 months of surgery. In conclusion, posterior and/or anterior decompression with spinal stabilization is a safe and effective treatment for patients with spinal metastases, and can improve their quality of life.

Translaminar screw fixation in the subaxial pediatric cervical spine

The use of spinal instrumentation to stabilize the occipitocervical junction in pediatric patients has increased and evolved in recent years. Wiring techniques have now given way to screw-rod or screw-plate techniques with or without postoperative external immobilization. Although C-2 translaminar screws have been used in these constructs, subaxial translaminar screws have not, to date, been described in either the pediatric or adult patient populations. The authors describe the feasibility of translaminar screw placement in the C-3 lamina. Rigid fixation with translaminar screws offers an alternative to subaxial fixation with lateral mass screws, allowing for formation of biomechanically sound spinal constructs and minimizing potential neurovascular morbidity. Their use requires careful analysis of preoperative imaging studies, intact posterior elements, and avoidance of violation of the inner laminar wall.

Does Acute Placement of Instrumentation in the Treatment of Vertebral Osteomyelitis Predispose to Recurrent Infection

Single institution, prospective observation study. To determine the long-term clinical outcomes of immune-suppressed patients with pyogenic vertebral osteomyelitis (PVO) treated with spinal instrumentation in the setting of active infection. The mainstay of treatment for PVO remains nonoperative. Surgical indications include neurologic compromise, deformity, abscess and failure of medical management. Some authors have been concerned regarding risk of local infection reoccurrence when spinal instrumentation has been placed in the setting of active infection. To our knowledge no long-term follow-up has been reported for this condition. Thirty-two consecutive immune compromised patients with PVO were treated with debridement and spinal instrumentation in the setting of acute infection at a single institution. Patients were observed by a set protocol and evaluated for reoccurrence of infection at regular intervals for up to 10 years. The 32 patients in our study group had significant medical comorbidities and were immune compromised. All patients were treated with single stage debridement and instrumented fusion during active infection. Twenty-two patients had a full 10 years follow-up without clinical recurrence of the local infection. Four patients died during the observation period, and none had clinic or autopsy evidence of recurrence. One patient developed recurrent infection after 14 months and was successfully treated with repeat debridement and retention of the instrumentation. Although this patient had a chronically infected vascular shunt, he was disease free at final follow-up of 10 years. Four patients had their implants removed for pain, suspected nonunion or suspected recurrent infection. None of these patients had histologic or microbacteriological evidence of injection. The use of spinal instrumentation in immune-compromised patients with PVO is associated with a low risk of long-term recurrent infection.

Congenital Scoliosis

Vertebral anomalies causing congenital scoliosis are classified on the basis of failures of formation, segmentation, or both. The natural history depends on the type of anomaly and the location of anomaly. Patient evaluation focuses on the history and physical examination, followed by appropriate imaging modalities. The hallmark of surgical treatment is early intervention before the development of large curvatures. The surgical treatment of a congenital deformity mandates the use of neurological monitoring to minimize the risk of perioperative neurological deficit. Modern surgical techniques have evolved to include the routine use of spinal instrumentation. Patients with associated chest wall deformities or large compensatory curves may be candidates for vertical expansion prosthetic titanium rib placement or growing rods insertion to maximize growth.

Spinal Epidural Abscess

Spinal epidural abscesses are often initially misdiagnosed, particularly in neurologically intact patients. Epidural infections can cause injury to the spinal cord. The incidence of these infections has increased with increasing use of spinal instrumentation, vascular access, and injection drugs. This review explains the diagnostic and therapeutic challenges and how to avoid spinal cord infarction.

Nationwide survey on complications of spine surgery in Japan

AbstractThe Japan Spine Research Society carried out a nationwide survey on complications of the spine, enrolling a total of 16 157 patients who had undergone spine surgery in 196 institutes in the 1-year period from January to December 2001. Diseases, surgical procedures, and complications were surveyed in detail. Forty-nine percent of patients were aged 60 years or older, which was remarkably increased in comparison with the percentage reported by the 1994 survey (37.3%). The number of cases with degenerative spinal diseases comprised 78.2% of the total number of spine surgery cases. The percentage of patients with stenosis was the greatest (38.5%), reflecting the increase in the elderly population undergoing spine surgery. Spinal instrumentation was used with 5497 patients (34.0%). The frequency of its use was much greater than that reported in 1994 (27.0%). The pedicle screw was the most frequently used instrument (54.6%). The use of spinal instrumentation greatly increased for spinal deformity, trauma, and tumors. Posterior lumbar interbody fusion has been increasingly used in cases of lumbar degenerative disease. Complications of spinal surgery were reported in 1383 patients (8.6%). The incidence of complications associated with instrumentation surgery was 12.1%, being twice as much as that associated with noninstrumentation surgery (6.8%).

Immediate stiffness of the C5-C6 segment after discectomy with the Cloward technique: an in vitro biomechanical study on a human cadaveric model.

To determine whether the Cloward technique of cervical discectomy and fusion increases immediate postoperative stiffness of single cervical motion segment after application of interbody dowel bone graft. We measured and compared the stiffness of single-motion segments in cadaveric cervical spines before and immediately after interbody fusion with the Cloward technique. Changes in range of motion and stiffness of the C5-C6 segment were measured in a bending flexibility test (flexion, extension, lateral bending and axial rotation) before and after a Cloward procedure in 11 fresh-frozen human cadaveric specimens from the 4th through the 7th vertebrae. The Cloward procedure produced a statistically significant increase in stiffness of the operated segment in flexion and lateral bending when compared with the intact spine. The less stiff the segment before the operation, the greater the increase in its postoperative flexural stiffness (statistically significant). The Cloward procedure produced nonuniform changes in rotational and extensional stiffness that increased in some specimens and decreased in others. Our data demonstrate that Cloward interbody fusion increases immediate postoperative stiffness of an operated segment only in flexion and lateral bending in cadaveric specimens in an in vitro environment. Thus, Cloward fusion seems a relatively ineffective method for increasing the stiffness of a construct. This may add to discussion on the use of spinal instrumentation and postoperative management of patients after cervical discectomy, which varies from bracing in hard collars through immobilization in soft collars to no external orthosis.