Safety and effectiveness of retrorectal presacral approach for lumbosacral axial instrumentation. A clinical study.

This prospective study aimed to quantify the risks and complications associated with AxiaLIF in a series of 29 patients. AxiaLIF is a fusion technique using a percutaneous retrorectal, presacral corridor approach to access the L5-S1 and L4-L5 intervertebral spaces transaxially, through the body of S1 and L5 vertebrae. The fusion rate in the present series was 92% and the reported results ranged from 68% to 100%. The only serious complication in the authors' series was one presacral haematoma (1/29, or 35%). Symptomatic subsidence occurred in the stand alone group, resulting in foraminal stenosis and radiculopathy in two patients (7%) and back pain in one (3.5%). Painful radiolucent halo around the rod was noted in a spondylolytic case (1/29, or 3.5%); it resolved after transpedicular instrumentation. AxiaLIF is a novel truly minimally invasive technique not requiring blood transfusion and can be safely performed as a day surgery. Retroperitoneal haematoma, ureteral and vascular injuries can be avoided by respecting the regional anatomical landmarks as guided by accurate fluoroscopy. Only expanding haematomas may have to be drained. Bowel perforation can be prevented by gently sweeping away the rectum from the sacrum before inserting the guide probe.

Respiratory effects, hemodynamic changes and cement leakage during multilevel cement balloon kyphoplasty.

PURPOSE: The purpose of this study is to evaluate the effects of multilevel balloon kyphoplasty (BK) on blood pressure, blood gases and cement leakage. METHODS: This is a prospective study of 63 patients: 31 were treated for osteoporotic vertebral compressive fractures (OVCF) and 32 for osteolytic tumors (OT). Twenty-six patients were treated at 1 level, 15 at 2, 2 at 3, 6 at 4, 3 at 5, 4 at 6, 5 at 7 and 2 at 8. PPMA was used in 43 patients and calcium phosphate in 20. All patients were treated under general anesthesia with continuous invasive monitoring of hemodynamic changes, arterial blood gases and peripheral and regional cerebral oxygen saturation. RESULTS: Two patients had a transient drop in blood pressure between 21 and 42 % during simultaneous inflation of all four balloons at two levels and three more patients during cement injection (two PMMA, one calcium phosphate). Five patients had a cement leak (7.9 %), which was unrelated to the cement type or number of levels. Blood pressure, end-tidal carbon dioxide partial pressure and arterial oxygen partial pressure decreased statistically, but without any clinical significance after cement insertion. Peripheral and regional cerebral oxygen saturation remained unchanged. One-way ANOVA revealed no difference between these changes when clustered by the groups single level, two levels and three or more levels. CONCLUSION: BK performed under general anesthesia appears to be safe when applied in multiple levels in the same seating provided the balloons are inflated sequentially and not simultaneously and the cement is inserted slowly in a very doughy state. Close monitoring of cardiorespiratory factors is valuable. Its rare circulatory effects are unrelated to the number of levels or the cement type.

Kinematics of cervical total disc replacement adjacent to a two-level, straight versus lordotic fusion.

STUDY DESIGN: In vitro biomechanical study. OBJECTIVE: To characterize cervical total disc replacement (TDR) kinematics above two-level fusion, and to determine the effect of fusion alignment on TDR response. SUMMARY OF BACKGROUND DATA: Cervical TDR may be a promising alternative for a symptomatic adjacent level after prior multilevel cervical fusion. However, little is known about the TDR kinematics in this setting. METHODS: Eight human cadaveric cervical spines (C2-T1, age: 59 ± 8.6 years) were tested intact, after simulated two-level fusion (C4-C6) in lordotic alignment and then in straight alignment, and after C3-C4 TDR above the C4-C6 fusion in lordotic and straight alignments. Fusion was simulated using an external fixator apparatus, allowing easy adjustment of C4-C6 fusion alignment, and restoration to intact state upon disassembly. Specimens were tested in flexion-extension using hybrid testing protocols. RESULTS: The external fixator device significantly reduced range of motion (ROM) at C4-C6 to 2.0 ± 0.6°, a reduction of 89 ± 3.0% (P < 0.05). Removal of the fusion construct restored the motion response of the spinal segments to their intact state. The C3-C4 TDR resulted in less motion as compared to the intact segment when the disc prosthesis was implanted either as a stand-alone procedure or above a two-level fusion. The decrease in motion of C3-C4 TDR was significant for both lordotic and straight fusions across C4-C6 (P < 0.05). Flexion and extension moments needed to bring the cervical spine to similar C2 motion endpoints significantly increased for the TDR above a two-level fusion compared to TDR alone (P < 0.05). Lordotic fusion required significantly greater flexion moment, whereas straight fusion required significantly greater extension moment (P < 0.05). CONCLUSION: TDR placed adjacent to a two-level fusion is subjected to a more challenging biomechanical environment as compared to a stand-alone TDR. An artificial disc used in such a clinical scenario should be able to accommodate the increased moment loads without causing impingement of its endplates or undue wear during the expected life of the prosthesis.

Biomechanical evaluation of segmental occipitoatlantoaxial stabilization techniques.

STUDY DESIGN: Biomechanical study using human cadaveric cervical spines. OBJECTIVE: To evaluate the construct stability of 3 different segmental occipitoatlantoaxial (C0-C1-C2) stabilization techniques. SUMMARY OF BACKGROUND DATA: Different C0-C1-C2 stabilization techniques are used for unstable conditions in the upper cervical spine, all with different degrees of risk to the vertebral artery. Techniques with similar stability but less risk to the vertebral artery may be advantageous. METHODS: Six human cadaveric cervical spines (C0-C5) (age: 74 +/- 5.0 years) were used. After testing the intact spines, instability was created by transecting the transverse and alar ligaments. The spines were instrumented from the occiput to C2 using 3 different techniques which varied in their attachment to C2. All spines had 6 screws placed into the occiput along with lateral mass screws at C1. The 3 variations used in attachment to C2 were (1) C2 crossing laminar screws, (2) C2 pedicle screws, and (3) C1-C2 transarticular screws. The C1 lateral mass screws were removed before placement of the C1-C2 transarticular screws. Range of motion across C0-C2 was measured for each construct. The data were analyzed using repeated measures ANOVA. The following post hoc comparisons were made: (1) intact spine versus each of the 3 techniques, (2) laminar screw technique versus the pedicle screw technique, and (3) laminar screw technique versus the transarticular screw technique. The level of significance was alpha = 0.01 (after Bonferroni correction for 5 comparisons). RESULTS: All 3 stabilization techniques significantly decreased range of motion across C0-C2 compared to the intact spine (P < 0.01). There was no statistical difference among the 3 stabilization methods in flexion/extension and axial rotation. In lateral bending, the technique using C2 crossing laminar screws demonstrated a trend toward increased range of motion compared to the other 2 techniques. CT scans in both axial and sagittal views demonstrated greater proximity to the vertebral artery in the pedicle and transarticular screw techniques compared to the crossing laminar screw technique. CONCLUSION: Occipitoatlantoaxial stabilization techniques using C2 crossing laminar screws, C2 pedicles screws, and C1-C2 transarticular screws offer similar biomechanical stability. Using the C2 crossing laminar screw technique may offer an advantage over the other techniques due to the reduction of the risk to the vertebral artery during C2 screw placement.

Effect of two-level total disc replacement on cervical spine kinematics.

STUDY DESIGN: Biomechanical study using human cadaver spines. OBJECTIVE: To characterize kinematics of cervical spines implanted with total disc replacement (TDR) at 2-levels referencing the implanted and adjacent levels. SUMMARY OF BACKGROUND DATA: Cervical TDR is an appealing alternative to fusion particularly when treating multilevel disease, where the advantages of maintaining motion and reducing adjacent level stresses with TDR are compelling. To our knowledge there are no biomechanical studies evaluating multilevel cervical TDR. METHODS: Six human cadaveric cervical spine specimens (C3-C7, age: 57 +/- 12 years) were tested (i) intact, (ii) after TDR (Discover, DePuy, Raynham, MA) at C5-C6, and (iii) after additional TDR at C6-C7. Specimens were subjected to flexion/extension, lateral bending and axial rotation (+/-1.5 Nm). Segmental range of motion (ROM) was measured using optoelectronic instrumentation and fluoroscopy. RESULTS: Insertion of TDR at C5-C6 increased flexion/extension ROM of the implanted segment compared with intact (8.6 +/- 1.0 vs. 12.3 +/- 3.3 degrees , P < 0.025). The TDR maintained ROM to intact levels in lateral bending (7.4 +/- 2.6 vs 6.0 +/- 1.6, P > 0.025) and axial rotation (5.5 +/- 1.9 vs. 6.0 +/- 2.9, P > 0.025). The TDR at C5-C6 did not affect ROM at the adjacent levels. Implantation of a second TDR at C6-C7 maintained the ROM at that segment to intact values in flexion/extension (9.6 +/- 4.3 vs. 11.2 +/- 5.5, P > 0.025), lateral bending (6.1 +/- 4.0 vs. 4.1 +/- 2.1, P > 0.025), and axial rotation (6.7 +/- 3.6 vs. 5.5 +/- 3.7, P > 0.025). The second TDR at C6-C7 did not affect the ROM of the prosthesis implanted at C5-C6. Two-level TDR at C5-C6-C7 did not affect the ROM at C4-C5 in flexion/extension or axial rotation, however, in lateral bending a small increase occurred (8.9 +/- 3.6 vs. 10.1 +/- 4.5, P < 0.025). CONCLUSION: Cervical TDR at 2 levels can provide near-normal mobility at both levels without destabilizing the implanted segments or affecting adjacent segment motions. These observations lend support to the notion that single or multilevel cervical TDR may be advantageous when compared to fusion.

Percutaneous core excision and radiofrequency thermo-coagulation for the ablation of osteoid osteoma of the spine.

Percutaneous radiofrequency ablation is the treatment of choice for osteoid osteoma of the appendicular skeleton. However, difficulties in localizing the lesion in the spine and its proximity to neural elements have yet to make it the prevalent treatment for spine. This study assesses the safety and effectiveness of two percutaneous techniques for ablating osteoid osteoma of the spine. Seven patients were treated between 1998 and 2005. Four patients underwent percutaneous radiofrequency coagulation. The lesions were located at the articular processes of L3 and L4, the lamina of L3 and in the head of the 11th rib. Three patients with lesions in close proximity to neural structures (pedicle of T9, the posterolateral inferior aspect of L3 vertebral body and the inferior articular process of C5) were subjected to percutaneous core excision. Mean follow-up was 4.2 +/- 1.6 years. Three out of four patients who underwent radiofrequency ablation had an immediate and sustained response. One patient with a lesion in the head of the rib failed to respond. The three patients in the group of pecutaneous core excisional biopsy demonstrated immediate relief of pain. However, one patient experienced relapse of symptoms 6 months after transpedicular core excision. CT scan suggested partial targeting of the lesion that corroborated with histologic examination revealing only reactive tissue. Subsequent percutaneous core excision was successful. Therefore, the overall success rate was 85.7%. Mean VAS improved dramatically from 9 +/- 1 to 2 +/- 1 after surgery (P < 0.05). No neurological or other complications were encountered. This study indicates that radiofrequency ablation of spinal osteoid osteomas is safe and reasonably effective when an intact cortical shell separates the nidus from the neural elements. Percutaneous core excision can obviate the risk of thermal damage for lesions located in close proximity to the neural elements. Effectiveness of treatment can also be evaluated by CT scan and histological examination. Difficulties in targeting the nidus can lead to treatment failure. The minimal morbidity and the effectiveness of these minimally invasive procedures make them a valid alternative in the treatment of spinal osteoid osteoma.

Effect of the Total Facet Arthroplasty System after complete laminectomy-facetectomy on the biomechanics of implanted and adjacent segments.

BACKGROUND CONTEXT: Lumbar fusion is traditionally used to restore stability after wide surgical decompression for spinal stenosis. The Total Facet Arthroplasty System (TFAS) is a motion-restoring implant suggested as an alternative to rigid fixation after complete facetectomy. PURPOSE: To investigate the effect of TFAS on the kinematics of the implanted and adjacent lumbar segments. STUDY DESIGN: Biomechanical in vitro study. METHODS: Nine human lumbar spines (L1 to sacrum) were tested in flexion-extension (+8 to -6Nm), lateral bending (+/-6Nm), and axial rotation (+/-5Nm). Flexion-extension was tested under 400 N follower preload. Specimens were tested intact, after complete L3 laminectomy with L3-L4 facetectomy, after L3-L4 pedicle screw fixation, and after L3-L4 TFAS implantation. Range of motion (ROM) was assessed in all tested directions. Neutral zone and stiffness in flexion and extension were calculated to assess quality of motion. RESULTS: Complete laminectomy-facetectomy increased L3-L4 ROM compared with intact in flexion-extension (8.7+/-2.0 degrees to 12.2+/-3.2 degrees, p<.05) lateral bending (9.0+/-2.5 degrees to 12.6+/-3.2 degrees, p=.09), and axial rotation (3.8+/-2.7 degrees to 7.8+/-4.5 degrees p<.05). Pedicle screw fixation decreased ROM compared with intact, resulting in 1.7+/-0.5 degrees flexion-extension (p<.05), 3.3+/-1.4 degrees lateral bending (p<.05), and 1.8+/-0.6 degrees axial rotation (p=.09). TFAS restored intact ROM (p>.05) resulting in 7.9+/-2.1 degrees flexion-extension, 10.1+/-3.0 degrees lateral bending, and 4.7+/-1.6 degrees axial rotation. Fusion significantly increased the normalized ROM at all remaining lumbar segments, whereas TFAS implantation resulted in near-normal distribution of normalized ROM at the implanted and remaining lumbar segments. Flexion and extension stiffness in the high-flexibility zone decreased after facetectomy (p<.05) and increased after simulated fusion (p<.05). TFAS restored quality of motion parameters (load-displacement curves) to intact (p>.05). The quality of motion parameters for the whole lumbar spine mimicked L3-L4 segmental results. CONCLUSIONS: TFAS restored range and quality of motion at the operated segment to intact values and restored near-normal motion at the adjacent segments.

Altered disc pressure profile after an osteoporotic vertebral fracture is a risk factor for adjacent vertebral body fracture.

This study investigated the effect of endplate deformity after an osteoporotic vertebral fracture in increasing the risk for adjacent vertebral fractures. Eight human lower thoracic or thoracolumbar specimens, each consisting of five vertebrae were used. To selectively fracture one of the endplates of the middle VB of each specimen a void was created under the target endplate and the specimen was flexed and compressed until failure. The fractured vertebra was subjected to spinal extension under 150 N preload that restored the anterior wall height and vertebral kyphosis, while the fractured endplate remained significantly depressed. The VB was filled with cement to stabilize the fracture, after complete evacuation of its trabecular content to ensure similar cement distribution under both the endplates. Specimens were tested in flexion-extension under 400 N preload while pressure in the discs and strain at the anterior wall of the adjacent vertebrae were recorded. Disc pressure in the intact specimens increased during flexion by 26 +/- 14%. After cementation, disc pressure increased during flexion by 15 +/- 11% in the discs with un-fractured endplates, while decreased by 19 +/- 26.7% in the discs with the fractured endplates. During flexion, the compressive strain at the anterior wall of the vertebra next to the fractured endplate increased by 94 +/- 23% compared to intact status (p < 0.05), while it did not significantly change at the vertebra next to the un-fractured endplate (18.2 +/- 7.1%, p > 0.05). Subsequent flexion with compression to failure resulted in adjacent fracture close to the fractured endplate in six specimens and in a non-adjacent fracture in one specimen, while one specimen had no adjacent fractures. Depression of the fractured endplate alters the pressure profile of the damaged disc resulting in increased compressive loading of the anterior wall of adjacent vertebra that predisposes it to wedge fracture. This data suggests that correction of endplate deformity may play a role in reducing the risk of adjacent fractures.

Intradural tumours of the lumbar spine presenting with low back pain: report of two cases and review of the literature.

Two cases of spinal cord tumours (one schwannoma and one ependymoma) of the lumbar spine are reported. The treatment with radical excision and posterolateral fusion, along with adjuvant radiation therapy in the case with ependymoma was successful, with follow-up of six and seven years respectively. A literature review is presented, and a possible presentation with low back pain is analysed.

An evidence-based medicine approach in determining factors that may affect outcome in lumbar total disc replacement.

STUDY DESIGN: Literature research. OBJECTIVE: To analyze the available evidence about a variety of factors that might affect outcome of lumbar artificial disc replacement. SUMMARY OF BACKGROUND DATA: Evaluating the scientific merit of new technology is important for a clinician considering incorporating these techniques. An evidence-based medicine approach can aid in this decision-making process. METHODS: Eleven questions were asked about patient selection issues, surgical accuracy of placement, and evidence that motion preservation alters the natural history of degeneration. Studies where answers were found were ranked according to their level of evidence. RESULTS: The majority of studies found were level IV, with only limited numbers of higher level studies. Only lower level studies with conflicting results assess the effect on outcomes of single versus multilevel surgery, L4-L5 versus L5-S1 implantations, patient's age, and history of previous surgery. One lower level study suggests that mild-to-moderate facet degeneration does not influence outcomes. The extent of preoperative facet degeneration that can be accepted remains unclear, as level IV studies report degradation of facet degeneration after implantation. Higher level studies support the importance of surgical precision on clinical outcome and lower level studies give mixed results on the same issue. A level III prognostic study suggests that higher range of motion of the implanted segment may be associated with better outcomes, whereas 2 level IV therapeutic studies provide conflicting results. The incidence of adjacent level degeneration in lower level studies ranges between 17% and 28.6%, and can require additional surgery in 2% to 3% of patients. Two level IV studies suggest that preservation of motion may have a prophylactic effect on adjacent discs. CONCLUSION: Existing evidence does not provide definite conclusions in the majority of the questions regarding indications and factors that may affect outcomes. Where feasible, conclusions are mainly drawn from lower level, least reliable evidence. Highest quality data are short-term whereas longer-term data are of lower quality and in many instances conflicting. More high level studies with long-term follow-up are necessary to shed light to important clinical issues.

Enhancing the stability of anterior lumbar interbody fusion: a biomechanical comparison of anterior plate versus posterior transpedicular instrumentation.

STUDY DESIGN: Biomechanical study using human cadaver spines. OBJECTIVE: To assess the stabilizing effect of a supplemental anterior tension band (ATB, Synthes) plate on L5-S1 anterior lumbar interbody fusion (ALIF) using a femoral ring allograft (FRA) under physiologic compressive preloads, and to compare the results with the stability achieved using FRA with supplemental transpedicular instrumentation. SUMMARY OF BACKGROUND DATA: Posterior instrumentation can improve the stability of ALIF cages. Anterior plates have been proposed as an alternative to avoid the additional posterior approach. METHODS: Eight human specimens (L3 to sacrum) were tested in the following sequence: (i) intact, (ii) after anterior insertion of an FRA at L5-S1, (iii) after instrumentation with the ATB plate, and (iv) after removal of the plate and adding transpedicular instrumentation at the same level. Specimens were tested in flexion-extension, lateral bending, and axial rotation. Flexion-extension was tested under 0 N, 400 N, and 800 N compressive follower preload to simulate physiologic compressive preloads on the lumbar spine. RESULTS: Stand-alone FRAs significantly decreased the range of motion (ROM) in all tested directions (P < 0.05); however, the resultant ROM was large in flexion-extension ranging between 6.1 +/- 3.1 degrees and 5.1 +/- 2.2 degrees under 0 N to 800 N preloads. The ATB plate resulted in a significant additional decrease in flexion-extension ROM under 400 N and 800 N preloads (P < 0.05). The flexion-extension ROM with the ATB plate was 4.1 +/- 2.3 under 0 N preload and ranged from 3.1 +/- 1.8 to 2.4 +/- 1.3 under 400 N to 800 N preloads. The plate did not significantly decrease lateral bending or axial rotation ROM compared with stand-alone FRA (P > 0.05), but the resultant ROM was 2.7 +/-1.9 degrees and 0.9 +/- 0.6 degrees , respectively. Compared with the ATB plate, the transpedicular instrumentation resulted in significantly less ROM in flexion-extension and lateral bending (P < 0.05), but not in axial rotation (P > 0.05). CONCLUSION: The ATB plate can significantly increase the stability of the anterior FRA at L5-S1 level. Although supplemental transpedicular instrumentation results in a more stable biomechanical environment, the resultant ROM with the addition of a plate is small, especially under physiologic preload, suggesting that the plate can sufficiently resist motion. Therefore, clinical assessment of the ATB plate as an alternative to transpedicular instrumentation to enhance ALIF cage stability is considered reasonable.

Effect of uncovertebral joint excision on the motion response of the cervical spine after total disc replacement.

STUDY DESIGN: In vitro biomechanical study. OBJECTIVE: To quantify the effects of uncinatectomy on cervical motion after total disc replacement (TDR). SUMMARY OF BACKGROUND DATA: The effect of uncinatectomy on TDR motion is unknown. Partial uncinatectomy may be required to decompress the foramen; however, the residual uncinates can potentially limit TDR motion and serve as a source of progressive spondylosis. Complete resection of the uncinates may decrease this risk yet endanger destabilizing the segment. METHODS: Seven human cervical spines (C3-C7) (age, 63.4 +/- 6.9 years) were tested first intact and then after implantation of a metal-on-polyethylene ball-and-socket semiconstrained prosthesis at C5-C6. Following this, gradually increased uncinatectomy was performed in the following order: 1) right partial-posteromedial (two thirds), 2) right complete, and 3) bilateral complete resection. Specimens were tested in flexion-extension, lateral bending, and axial rotation (+/-1.5 Nm). Flexion-extension was tested under 150 N follower preload. RESULTS: TDR without uncinatectomy increased C5-C6 flexion-extension range of motion from 8.4 degrees +/- 3.5 degrees to 11.6 degrees +/- 3.4 degrees, but statistical significance was not reached (P > 0.05). Lateral bending decreased from 6.2 degrees +/- 2.2 degrees to 3.1 degrees +/- 1.4 degrees, with a trend for statistical significance (P = 0.07). Axial rotation decreased from 5.5 degrees +/- 2.4 degrees to 4.3 degrees +/- 1.4 degrees after the implantation (P > 0.05). Both right partial and right complete uncinatectomy resulted in nearly symmetrical restoration of lateral bending to intact values and significantly increased flexion-extension compared with intact (P < or = 0.05); however, axial rotation still did not differ from intact (P > 0.05). Complete bilateral resection also restored lateral bending to intact values (7.3 degrees +/- 2.7 degrees, P > 0.05); however, it resulted in significant increase in range of motion in flexion-extension (14.1 degrees +/- 3.0 degrees, P < or = 0.05) and axial rotation (8.7 degrees +/- 2.4 degrees, P < or = 0.05). CONCLUSION: Unilateral complete or even partial uncinatectomy can normalize lateral bending after TDR. Bilateral complete uncinatectomy is not necessary to restore lateral bending and may result in significantly increased range of motion in flexion-extension and axial rotation compared with intact values.

Biomechanics of the posterior lumbar articulating elements.

The clinical success of lumbar spinal fusion varies considerably, depending on techniques and indications. Although spinal fusion generally helps to eliminate certain types of pain, it may also decrease function by limiting patient mobility. Furthermore, spinal fusion may increase stresses on adjacent nonfused motion segments, accelerating the natural degeneration process at adjacent discs. Additionally, pseudarthrosis, that is, incomplete or ineffective fusion, may result in an absence of pain relief. Finally, the recuperation time after a fusion procedure can be lengthy. The era of disc replacement is in its third decade, and this procedure has demonstrated promise in relieving back pain through preservation of motion. Total joint replacement with facet arthroplasty of the lumbar spine is a new concept in the field of spinal surgery. The devices used are intended to replace either the entire functional spinal unit (FSU) or just the facets. These devices provide dynamic stabilization for the functional spinal segment as an adjunct to disc replacement or laminectomy and facetectomy performed for neural decompression. The major role of facet replacement is to augment the instabilities created by the surgical decompression or to address chronic instability. Additionally, facet joint replacement devices can be used to replace the painful facet joints, restore stability, and/or to salvage a failed disc or nucleus prosthesis without losing motion. In this paper the authors review and discuss the role of the lumbar facet joints as part of the three-joint complex and discuss their role in intersegmental motion load transfer and multidirectional flexibility in a lumbar FSU.

Postoperative infections of the thoracic and lumbar spine: a review of 18 cases.

We retrospectively reviewed 18 consecutive patients (age range, 19-81 years; average age, 55 years) with postoperative infections of the spine. Postdiscectomy-laminectomy infections confined to the disc space (n = 2) were treated with percutaneous transpedicle drainage. Open débridement was performed in patients with an epidural or paraspinal abscess (n = 3). Infections after posterior instrumentation that manifested during the first postoperative month were treated with single (n = 3) or multiple débridements and delayed closure (n = 7), with preservation of instrumentation. Infections that presented more than 9 months after the initial operation (n = 3) were treated with open débridement and removal of instrumentation. The minimum followup was 1 year (mean 2 years, range, 1-4 years). Infections in 17 of the 18 patients resolved effectively and one patient with metastatic cancer died of sepsis. Transpedicle drainage resulted in immediate relief of back pain. Instrumentation can be retained safely in patients with infections that manifest during the first month after implantation. Single surgical débridement is effective in selected cases. After repeated débridements, the presence of healthy granulation tissue in the wound and decreasing C-reactive protein activity were associated with safe and effective wound closure. Despite radiographic evidence of hardware loosening in infections manifested more than 9 months after implantation, we removed hardware without destabilizing the spine.

Surgical treatment of spinal brucellosis.

UNLABELLED: We retrospectively reviewed 10 patients with spinal brucellosis of the thoracic and lumbar spine who were treated successfully with a combination of surgery and antibiotics. All patients had back pain; six patients had radiculopathy and one patient had paraparesis. Patients with spondylodiscitis without epidural abscesses (n = 3) had transpedicle discectomy and drainage. Epidural abscesses in the lumbar area caused by spondylodiscitis (n = 3), spondylitis (n = 2), and discitis with infected disc herniation (n = 1), were drained using a posterior approach combined with posterolateral fusion in two patients with spondylodiscitis and discectomy in the patient with a herniated disc. One patient presented with a pathologic fracture and neural compression and was treated with anterior corpectomy and reconstruction. Antibiotic treatment was given for 3 to 9 months. Mean followup was 3 years. Back pain improved soon after surgery. Recovery from radiculopathy and paraparesis was complete. One patient had recurrence of infection 9 months after initial treatment. Clinical manifestation of spinal brucellosis can include spondylitis, spondylodiscitis, discitis, epidural abscess, paraspinal abscess, and vertebral collapse. Transpedicle drainage allows tissue diagnosis and facilitates treatment. Because brucellosis usually responds to antibiotics, surgery is considered as the last resort in treating spinal brucellosis, but severe neurologic deficit and incapacitating back pain often necessitate surgical intervention. LEVEL OF EVIDENCE: Therapeutic study, level IV (case series). Please see the Guidelines for Authors for a complete description of levels of evidence.

Balloon kyphoplasty for the treatment of pathological vertebral compressive fractures.

BACKGROUND: Previous clinical studies have shown the safety and effectiveness of balloon kyphoplasty in the treatment of pathological vertebral compression fractures (VCFs). However, they have not dealt with the impact of relatively common comorbid conditions in this age group, such as spinal stenosis, and they have not explicitly addressed the use of imaging as a prognostic indicator for the restoration of vertebral body height. Neither have these studies dealt with management and technical problems related to surgery, nor the effectiveness of bone biopsy during the same surgical procedure. This is a prospective study comparing preoperative and postoperative vertebral body heights, kyphotic deformities, pain intensity (using visual analogue scale) and quality of life (Oswestry disability questionnaire) in patients with osteoporotic vertebral compression fractures (OVCFs) and osteolytic vertebral tumors treated with balloon kyphoplasty. METHODS: Thirty-two consecutive patients, 27 OVCFs (49 vertebral bodies [VBs]) and 5 patients suffering from VB tumor (12 VBs) were treated by balloon kyphoplasty. The mean age was 68.2 years. All patients were assessed within the first week of surgery, and then followed up after one, three and six months; all patients (27 OVCFs and 5 tumor patients) were followed up for 12 months, 17 patients (14 OVCFs and 3 tumors) were followed up for 18 months and 9 patients (8 OVCFs and 1 tumor) were followed up for 24 months (mean follow up 18 months). The correction of kyphosis and vertebral heights were measured by comparing preoperative and postoperative radiographic measurements. RESULTS: Thirty-one patients (96.9%) exhibited significant and immediate pain improvement: 90% responded within 24 h and 6.3% responded within 5 days. Daily activities improved by 53% on the Oswestry scale. In the OVCF group, kyphosis correction was achieved in 24/27 patients (89.6%) with a mean correction of 7.6 degrees . Anterior wall height was restored in 43/49 VBs (88%) (mean increment of 4.3 mm), and mid vertebral body height was restored in 45/49 VBs (92%) (mean increment of 4.8 mm). Edema (high intensity signal) on short tau inversion recovery (STIR) was evidenced in all OVCF patients who experienced symptoms for less than nine months and was associated with correction of deformity. Cement leakage was the only technical problem encountered; it occurred in 5/49 VBs (10.2%) of the osteoporotic group and 1/12 VBs (8.3%) of the tumor group but had no clinical consequences. The incidence of leakage to the anterior epidural space was 2%. Spinal stenosis was present in three patients (11.1%) who responded successfully to subsequent laminectomy. Retrieval of tissue samples for biopsy was successful in 10/15 cases (67%). New fractures occurred in the adjacent level in 2/27 OVCF patients (7.4%). CONCLUSIONS: Associated spinal stenosis with OVCF should not be overlooked; STIR MRI is a good predictor of deformity correction with balloon kyphoplasty. The prevalence of a new OVCF in the adjacent level is low.

Principles of management of osteometabolic disorders affecting the aging spine.

Osteoporosis is the most common contributing factor of spinal fractures, which characteristically are not generally known to produce spinal cord compression symptoms. Recently, an increasing number of medical reports have implicated osteoporotic fractures as a cause of serious neurological deficit and painful disabling spinal deformities. This has been corroborated by the present authors as well. These complications are only amenable to surgical management, requiring instrumentation. Instrumenting an osteoporotic spine, although a challenging task, can be accomplished if certain guidelines for surgical techniques are respected. Neurological deficits respond equally well to an anterior or posterior decompression, provided this is coupled with multisegmental fixation of the construct. With the steady increase in the elderly population, it is anticipated that the spine surgeon will face serious complications of osteoporotic spines more frequently. With regard to surgery, however, excellent correction of deformities can be achieved, by combining anterior and posterior approaches. Paget's disease of bone (PD) is a non-hormonal osteometabolic disorder and the spine is the second most commonly affected site. About one-third of patients with spinal involvement exhibit symptoms of clinical stenosis. In only 12-24% of patients with PD of the spine is back pain attributed solely to PD, while in the majority of patients, back pain is either arthritic in nature or a combination of a pagetic process and coexisting arthritis. In this context, one must be certain before attributing low back pain to PD exclusively, and antipagetic medical treatment alone may be ineffective. Neural element dysfunction may be attributed to compressive myelopathy by pagetic bone overgrowth, pagetic intraspinal soft tissue overgrowth, ossification of epidural fat, platybasia, spontaneous bleeding, sarcomatous degeneration and vertebral fracture or subluxation. Neural dysfunction can also result from spinal ischemia when blood is diverted by the so-called "arterial steal syndrome". Because the effectiveness of pharmacologic treatment for pagetic spinal stenosis has been clearly demonstrated, surgical decompression should only be instituted after failure of antipagetic medical treatment. Surgery is indicated as a primary treatment when neural compression is secondary to pathologic fractures, dislocations, spontaneous epidural hematoma, syringomyelia, platybasia, or sarcomatous transformation. Five classes of drugs are available for the treatment of PD. Bisphosphonates are the most popular antipagetic drug and several forms have been investigated.