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K Daniel Riew

Publications and source records attributed to K Daniel Riew.

36 records · Page 2Linked to original sources
PubMed2004

Posterior instrumentation using compressive laminar hooks and anterior interbody arthrodesis for the treatment of tuberculosis of the lower lumbar spine.

STUDY DESIGN: A retrospective review with clinical and radiologic assessment was conducted. OBJECTIVE: To demonstrate the feasibility of posterior short segment augmentation with lamina hook and anterior lumbar interbody arthrodesis in tuberculosis of the lumbar spine by evaluating clinical results, fusion status, and sagittal angle. SUMMARY OF BACKGROUND DATA: There are few articles in the literature describing circumferential treatment of lumbar tuberculosis. We have had significant experience with a uniform operative technique for the treatment of this relatively rare condition and report our results with a minimum 2-year follow-up. METHODS: Twenty-three patients with tuberculosis of the lower lumbar spine underwent posterior instrumentation with laminar hooks and anterior interbody arthrodesis by a single surgeon. The clinical outcomes were evaluated with preoperative and postoperative questionnaires, and the radiographs were independently analyzed with respect to fusion status and sagittal angle. RESULTS.: The mean follow-up period was 28.7 months (range, 24-39 months). The average preoperative, immediate postoperative, and final follow-up sagittal angles were 2.7 degrees, -14.1 degrees, and -11.5 degrees, respectively. There was a mean reduction of 16.7 degrees (range, 9 degrees-23 degrees) after surgery. Two patients had a correction loss more than 5 degrees during the follow-up period. Bony fusion was obtained in all patients. There was no recurrence of the disease. CONCLUSION.: This technique appears to be effective in stabilizing the vertebrae, restoring lordosis, achieving a solid fusion, and improving clinical outcome without sacrificing additional motion segments.

Adult↗
PubMed2004

Free hand pedicle screw placement in the thoracic spine: is it safe?

STUDY DESIGN: A retrospective study. OBJECTIVE: To evaluate the safety of a free hand technique of pedicle screw placement in the thoracic spine at a single institution over a 10-year experience. SUMMARY OF BACKGROUND DATA: Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic. MATERIALS AND METHODS: Three hundred ninety-four consecutive patients who underwent posterior stabilization utilizing 3204 transpedicular thoracic screws by 2 surgeons from 1992 to 2002 were analyzed. The mean age was 27 + 10 years (range 5 + 3-87 + 0 years) at the time of surgery. Etiologic diagnoses were: scoliosis in 273, kyphosis in 53, other spinal disease in 68. Pedicle screws were inserted using a free hand technique similar to that used in the lumbar spine in which anatomic landmarks and specific entry sites were used to guide the surgeon. A 2-mm tip pedicle probe was carefully advanced free hand down the pedicle into the body. Careful palpation of all bony borders (floor and four pedicle walls) was performed before and after tapping. Next, the screw was placed, followed by neurophysiologic (screw stimulation with rectus abdominus muscle recording) and radiographic (anteroposterior and lateral) confirmation. An independent spine surgeon using medical records and roentgenograms taken during treatment and follow-up reviewed all the patients. RESULTS: The number of the screws inserted at each level were as follows (total n = 3204): T1, n = 13; T2, n = 60; T3, n = 192; T4, n = 275; T5, n = 279; T6, n = 240; T7, n = 230; T8, n = 253; T9, n = 259; T10, n = 341; T11, n = 488; T12, n = 572. Five hundred seventy-seven screws inserted into the deformed thoracic spine were randomly evaluated by thoracic computed tomography scan to assess for screw position. Thirty-six screws (6.2%) were inserted with moderate cortical perforation, which meant the central line of the pedicle screw was out of the outer cortex of the pedicle wall and included 10 screws (1.7%) that violated the medial wall. There were no screws (out of the entire study group of 3204) with any neurologic, vascular, or visceral complications with up to 10 years follow-up. CONCLUSIONS: The free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

Adolescent↗
PubMed2004

Accurate identification of adverse outcomes after cervical spine surgery.

BACKGROUND: Retrospective clinical studies frequently utilize surgeon records as a source of outcomes data. The accuracy of data derived from surgeon records, however, is unknown. The purpose of the present study was to evaluate the accuracy of surgeon records in documenting the prevalence of subjective adverse outcomes. METHODS: Consecutive patients who had undergone anterior cervical arthrodesis by four spine surgeons during a ten-month period were included. Surgeon records from the routine six-week, three-month, and six-month postoperative visits were examined for documentation of persistent dysphagia and dysphonia. Patients completed surveys inquiring about the presence and magnitude of symptoms at these three time-points. Agreement between the surgeon records and the patient surveys was analyzed with use of the kappa coefficient. RESULTS: One hundred and sixty-six patients had 342 postoperative visits. Dysphagia was documented twenty-six times in the surgeon records, compared with 107 times on the patient surveys. Dysphagia was thus underreported in 80% of cases. Similarly, dysphonia was documented ten times in the surgeon records, compared with seventy-two times on the patient surveys. Poor correlation between the surgeon records and the patient surveys was observed regardless of symptom severity, previous anterior cervical surgery, anterior arthrodesis of three motion segments or more, arthrodesis cephalad to the fifth cervical level, and anterior cervical plate use. Poor correlation between the surgeon records and the patient surveys also was observed for each surgeon, regardless of subspecialty or institution. CONCLUSIONS: Correlation between the surgeon records and the patient surveys was consistently poor, regardless of the specific patient and surgeon factor analyzed. While we chose to study dysphonia and dysphagia, it is conceivable that the results may be generalizable to many situations in which office notes are utilized to ascertain the prevalence of subjective adverse outcomes. These results suggest that the prevalence of such outcomes may be seriously underreported in studies that rely on the retrospective analysis of surgeon records.

Adolescent↗
PubMed2004

A comparison of simulator-tested and -retrieved cervical disc prostheses. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004.

OBJECT: Total joint arthroplasties most commonly fail because the implant becomes worn and a host inflammatory response subsequently develops. Both the material response to the biological environment and the host response to the device must be thoroughly evaluated to establish the efficacy of cervical arthroplasty. Analyses of devices explanted in humans allow evaluation of both responses. Hypothetical wear rates can be determined by comparing in vivo wear with simulator-derived wear. The purpose of this study was to perform explant analyses involving the Bryan and Prestige discs and compare these results with those obtained using spine simulators. METHODS: Of the approximately 5500 patients treated with the Bryan disc, 11 have undergone explantation of the device. Six of these devices were analyzed for dimensional and chemical changes. Three of the approximately 300 implanted Prestige discs were retrieved, and two were examined microscopically. Histological specimens were assessed for wear particles and host inflammatory response. Additionally, the extent of simulator-produced wear was compared with that demonstrated in the retrieved specimens. CONCLUSIONS: The simulator-generated results predict adequate wear-related characteristics for both the Bryan and Prestige prostheses for a minimum of 40 years. Comparison of data with those of the retrieved specimens indicates that the wear was more minimal than predicted in simulators by five- to 10-fold. In no instance did the revisions result from failure of the device due to a reaction to wear debris, fracture, polymer oxidation, or metal corrosion. The inflammatory response seen in the periprosthetic tissues was minimal and not characteristic of inflammatory responses in failed diarthrodial joint arthroplasties.

Alloys↗
PubMed2003

Time-dependent inhibitory effects of indomethacin on spinal fusion.

BACKGROUND: The use of nonsteroidal anti-inflammatory drugs following spine arthrodesis is discouraged because of the negative effects on bone-healing. We are not aware of any data regarding when nonsteroidal anti-inflammatory drugs may be safely resumed postoperatively. We hypothesized that these drugs have a time-dependent deleterious effect on fusion, with the greatest inhibition during the early phases of fusion. METHODS: Seventy New Zealand White rabbits underwent posterior intertransverse process arthrodesis at L5-L6 with use of iliac autograft. Rabbits randomly received indomethacin (10 mg/kg orally) starting at two weeks after surgery (twenty-four animals), indomethacin starting at four weeks postoperatively (twenty-three), or saline starting at two weeks postoperatively (twenty-three) (the control group). The animals were killed at six weeks, and the spines were denuded of soft tissues and palpated for L5-L6 motion. Fusion was defined as the complete absence of motion. RESULTS: Sixty-five percent (fifteen) of the twenty-three spines in the control group and 48% (eleven) of the twenty-three in the four-week group fused. However, only 21% (five) of the twenty-four spines in the two-week group fused. The difference between the two-week and control groups was significant (p < 0.002), as was the difference between the two and four-week groups (p = 0.05). The difference between the four-week and control groups was not significant (p = 0.2). CONCLUSIONS: The earlier that indomethacin was resumed postoperatively, the greater was its negative effect on fusion. Indomethacin appears to play a significant inhibitory role in the early phase of healing. Initiating indomethacin treatment in the latter phase of healing does not appear to significantly affect fusion rates, although there was a nonsignificant trend toward inhibition. To our knowledge, this is the first investigation of the time-dependent nature of indomethacin's effect on bone-healing.

Animals↗
PubMed2003

Thoracoscopic intradiscal spine fusion using a minimally invasive gene-therapy technique.

BACKGROUND: Gene therapy has been utilized to achieve posterior intertransverse process fusion in rodents. To our knowledge, however, no one has previously reported on the use of this technique to achieve anterior spinal fusion in mammals. The purpose of the present study was to determine if a gene-therapy technique can be utilized to achieve anterior intradiscal fusion in pigs with use of minimally invasive techniques. METHODS: Mesenchymal stem cells were isolated from each of three pigs, expanded in culture, and transduced with an adenovirus carrying either the gene for bone morphogenetic protein-2 (Adv-BMP2) or the control gene, beta-galactosidase (Adv-betagal). In vitro, assays were performed to detect BMP-2 expression as well as protein markers of bone formation. In vivo, four thoracic disc spaces in each of three pigs were injected thoracoscopically with cells after 1 cm (3) of the disc had been removed. In each of the three pigs, two discs were injected with autologous mesenchymal stem cells transduced with Adv-BMP2, the third disc was injected with cells transduced with Adv-betagal (control 1), and the fourth disc served as the sham-operated control (control 2). The three animals were killed six weeks after the implantation. Computerized tomographic scanning was performed on two of the specimens, and histological examination was performed on all specimens. The computerized tomographic scans and histological examinations were then interpreted in a blinded fashion. RESULTS: In the in vitro study, a human BMP-2 protein band was detected in the medium of Adv-BMP2-transduced stem cells but not in that of the control cells. The Adv-BMP2-transduced stem cells were associated with a fivefold increase in alkaline phosphatase activity compared with the controls as well as with matrix mineralization and increased protein expression of type-I collagen, osteopontin, and bone sialoprotein. In the in vivo study, radiographic examination demonstrated anterior spinal fusion in all six disc spaces that had been treated with implantation of Adv-BMP2-transduced stem cells. In contrast, the six control disc spaces had little or no intervening bone. Histological examination demonstrated bridging bone from end plate to end plate in all six disc spaces that had been treated with implantation of Adv-BMP2-transduced stem cells. The six control disc spaces had no bridging bone. CONCLUSION: The Adv-BMP2-transduced mesenchymal stem cells produced BMP-2 protein. Further, the cells differentiated into osteoblasts and induced anterior spinal fusion in six of six disc spaces in this pig model. Although many technical and practical challenges remain, the results of the present study suggest that it may eventually be possible to use similar techniques to achieve anterior spinal fusion in humans.

Animals↗
PubMed2003

Microsurgery for degenerative conditions of the cervical spine.

Although the operating microscope has been used for spine surgery for more than 20 years, its use is still not widely accepted by orthopaedic spine surgeons. Nevertheless, surgeons who have used the operating microscope are well aware of its many advantages in performing spine surgery. Most notably, the superior visualization it provides allows for faster, safer, and more extensive decompressions. The reluctance of many surgeons to use the operating microscope often has to do with trepidation regarding new technology. The use of the operating microscope when performing anterior and posterior cervical spine surgery makes these procedures easier to carry out and decreases the risk of complications during decompression of the spinal cord.

Cervical Vertebrae↗
PubMed2002

The use of titanium mesh cages in the cervical spine.

Titanium mesh cages have been used widely for spinal reconstruction since 1986 when they first were introduced. Despite their popularity, relatively few studies have been published on their use in the cervical spine. These cages can be used as structural devices containing autologous local bone or iliac crest bone graft, obviating the need to harvest large structural bone grafts. The main disadvantages of their use are the increased costs and the difficulty of assessing fusion status. The authors review surgical techniques that can be used using titanium mesh cages in cervical spine applications and discuss some of their advantages and disadvantages.

Cervical Vertebrae↗
PubMed2002

Mesh cages for spinal deformity in adults.

Correction of deformity including restoration of sagittal plane malalignment in patients with spinal disorders is facilitated by placement of structural allografts and cages into the anterior column. The effectiveness of these implants will be reviewed with a focus on anterior column implantation of titanium mesh cages. In a consecutive study of adult patients who had spinal fusions for sagittal plane deformities using structural titanium mesh cages, cage status, fusion status, and outcome were assessed. Followup ranged from 24 to 62 months (average, 33 months). No cage failure of extrusion was observed. The average segmental improvement in lordosis with cage implantation was 11 degrees with a loss of correction of less than 1 degree at latest followup. No radiographic gold standard for fusion assessment with metallic implants in the anterior column could be found in the literature. The use of radiographic techniques for fusion assessment and functional outcome data for patients with implanted titanium mesh cages will be discussed.

Adult↗
PubMed2002

The effect of cyclooxygenase-2 inhibitors on spinal fusion.

BACKGROUND: Spine surgeons discourage the use of nonsteroidal anti-inflammatory drugs following spine arthrodesis because of their inhibitory effect on bone-healing. To our knowledge, there are no data on the effects of the new cyclooxygenase-2 inhibitors on bone-healing. We undertook this study to determine the effects of these more selective nonsteroidal anti-inflammatory drugs on spinal fusion in a rabbit model. METHODS: Seventy-two New Zealand White rabbits underwent a posterolateral intertransverse process arthrodesis with use of autologous iliac crest bone. Sixty-six rabbits survived the surgical procedure and the perioperative period and had an uneventful postoperative course. These rabbits were randomly divided into three groups. One group received 10 mg/kg of celecoxib orally, the second group received 10 mg/kg of indomethacin orally, and the third group (the control group) received 1 cm (3) of saline solution orally. The rabbits received the treatment daily for eight weeks, after which they were killed and the lumbar spine was harvested. The specimens were palpated for motion, radiographed, and prepared for histological analysis. The quality of the fusion was graded at each level by assigning a histological score of 0 to 7. RESULTS: Gross inspection and palpation revealed that 64% (fourteen) of the twenty-two control spines and 45% (ten) of the twenty-two spines in the rabbits treated with celecoxib were fused. With the numbers available, this difference was not significant (p = 0.224). Of the twenty-two spines in the indomethacin-treated rabbits, 18% (four) were fused, and this percentage was significantly different from the control value (p = 0.002). On radiographic assessment, the spine segment was deemed to be fused in 82% (eighteen) of the twenty-two controls, 86% (nineteen) of the twenty-two rabbits treated with celecoxib, and 41% (nine) of the twenty-two indomethacin-treated animals. Only the difference between the indomethacin-treated and control groups was significant (p = 0.004). The histological scores averaged 5.2, 4.8, and 3.5 for the control, celecoxib, and indomethacin groups, respectively. There was a significant difference between the control and indomethacin groups (p = 0.002) but not between the celecoxib and control groups (p = 0.161). CONCLUSIONS: These results suggest that celecoxib does not significantly inhibit the rate of spinal fusion in rabbits. They also suggest that the inhibitory effects of nonsteroidal anti-inflammatory drugs on bone-healing are likely mediated by inhibition of cyclooxygenase-1 and that celecoxib is the better choice if treatment with nonsteroidal anti-inflammatory drugs is deemed necessary following spinal arthrodesis.

Administration, Oral↗
PubMed2002

A comprehensive study of patients with surgically treated lumbar spinal stenosis with neurogenic claudication.

BACKGROUND: The relationship between objective measurements and subjective symptoms of patients with spinal stenosis and the degree of narrowing of the spinal canal is not clear. The purpose of this study was to evaluate patients undergoing surgery for lumbar spinal stenosis and intermittent neurogenic claudication with functional testing, quantitative imaging, and patient self-assessment. METHODS: Sixty-two patients with lumbar spinal stenosis and neurogenic claudication were prospectively enrolled in the study. All underwent preoperative magnetic resonance imaging and/or computed tomography myelography, and all were treated with decompressive surgery and were followed for a minimum of two years. The evaluation included treadmill and bicycle exercise tests as well as patient self-assessment with use of the Oswestry Disability Index and a visual analog pain scale preoperatively and postoperatively. RESULTS: Preoperatively fifty-eight (94%) of the patients had a positive result (provocation of symptoms) on the treadmill test and twenty-seven (44%) had a positive result on the bicycle test, whereas postoperatively six and twelve, respectively, had positive results. The mean preoperative scores on the Oswestry Disability Index and visual analog pain scale were 58.4 and 7.1, respectively. Postoperatively, these scores decreased to 21.1 and 2.3, respectively, and both decreases were significant (p < 0.05). Forty-seven (76%) of the patients were seen to have central stenosis on the preoperative imaging studies; forty-one of them had a cross-sectional area of the dural tube of <100 mm (2) at at least one level and twelve had a cross-sectional area of <100 mm (2) at at least two levels. CONCLUSIONS: A positive treadmill test was consistent with a diagnosis of spinal stenosis and neurogenic claudication in >90% of the patients preoperatively. Following surgical decompression of the lumbar spinal stenosis, more functional improvement was demonstrated by the treadmill test than by the bicycle test. The scores on the Oswestry Disability Index and visual analog pain scale also improved postoperatively. The severity of central canal narrowing at a single level does not appear to limit the postoperative improvement in either functional ability or patient self-assessment. Patients with multilevel central stenosis were, on the average, older and walked a shorter distance preoperatively and postoperatively, although the improvement in their postoperative self-assessment scores was similar to that of patients with single-level stenosis.

Aged↗
PubMed2002

Microsurgical techniques in lumbar spinal stenosis.

The rationale for microsurgical decompression is to maximize neural decompression while minimizing the destabilization and resection of uninvolved structures. Microsurgical decompression is appropriate for most degenerative lumbar spinal stenosis because the pathoanatomy tends to be concentrated at the levels of the disk space and foramen. Careful preoperative analysis of the imaging studies will guide the surgeon to the most appropriate method of decompression for a particular patient and help focus the decompression to the appropriate regions. Thorough knowledge of surgical spinal anatomy is mandatory because the exposure is limited with a microsurgical approach; however, visualization can be excellent with proper attention to surgical technique.

Decompression, Surgical↗
PubMed2001

Long-term complications in adult spinal deformity patients having combined surgery a comparison of primary to revision patients.

STUDY DESIGN: This is a comparison of primary (N = 18) to revision (N = 26) combined (anterior and posterior surgery) adult spinal deformity patients with regard to late (>6 months) complications and radiographic/functional outcomes at a minimum 2-year follow-up. OBJECTIVES: To determine whether revision status increases the risk of late complications or offers a poor prognosis for functional outcome in adult deformity patients. SUMMARY OF BACKGROUND DATA: It is known that patients who have combined surgery for adult deformity have a high incidence of perioperative complications. Long-term complications and the effect of revision status have not been clarified in the literature. The functional outcomes for these patients are unclear as to whether or not there is a difference between primary and revision patients. Outside the arena of adult spinal deformity the functional outcomes for revision cases have been disappointing. METHODS: A consecutive series of 44 patients who underwent combined procedures for adult spinal deformity were followed for a minimum of 2 years (average follow-up 42 months). Clinical data were obtained by chart and radiographic review. Major complications were considered to be deep wound infection, pseudarthrosis, transition syndrome, neurologic deficit, and death. Minor complications considered were asymptomatic instrumentation failure (without loss of correction), instrumentation prominence requiring removal, and proximal or distal junctional segmental kyphosis (5-10 degrees ) or subsequent disc space narrowing of 2-5 mm without clinical symptoms. The patients also completed the AAOS Lumbar/Scoliosis MODEMS questionnaires aimed at assessing pain, function, and satisfaction. RESULTS: Minor complications were comparable in both groups: 4 of 18 (22%) in the primary group and 6 of 26 (23%) in the revision group. Major complications were slightly more frequent in the primary group with five complications in 4 patients (4 of 18 patients) (22%) compared with 3 of 26 patients (12%) in the revision group. The incidence of pseudarthrosis was 22% (4 of 18) for the primary group and 4% (1 of 26) for the revision group (P< 0.14). Forty of 44 patients completed the questionnaires. The primary patients functioned at a slightly higher level after surgery than the revision group. The level of pain was also slightly lower at final follow-up in the primary group. Despite these differences, the revision group had a higher level of patient satisfaction. CONCLUSION: At a minimum 2-year follow-up the late complications were not higher in the revision patients than in the primary group. The rate of major long-term complications, specifically pseudarthroses, was higher in the primary group. Patient satisfaction was higher in the revision patients, probably because they were experiencing a greater level of perceived pain and dysfunction at the time of their reconstruction.

Adult↗
PubMedDate not supplied

Influence of needle-tip position on the incidence of immediate complications in 2,217 selective lumbar nerve root blocks.

BACKGROUND CONTEXT: Selective lumbar nerve blocks (SLNBs) are a popular, minimally invasive treatment and diagnostic tool for lumbar radiculopathy. It is therefore relevant to determine the complication rate for SLNBs, as well as examine the association between needle-tip position and complication rates in order to improve safety. PURPOSE: The purposes of the present study are to determine the overall rate of immediate, postprocedural complications in a large cohort of patients who received SLNBs and determine if certain needle-tip positions are less likely to cause complications. To our knowledge, this is the first paper to examine the relationship between needle-tip position and complications. STUDY DESIGN: A large retrospective cohort was assembled from patients who had undergone a SLNB. We determined the overall immediate complication rate for all injections. In addition, all patients who received only a single injection were compiled into another cohort, and needle-tip position was determined. The complication rate was determined for each needle-tip position. PATIENT SAMPLE: All adult patients who underwent a SLNB in a single radiology department from April 1, 1997 to May 31, 2002. OUTCOME MEASURES: Patients were observed for 15-30 minutes after their procedure, then interviewed about any self-reported weakness, light-headedness, increase in pain from the preprocedural levels, or development of new pain. Their postprocedural pain was then rated on the Visual Analogue Scale. The radiologic notes from each examination were reviewed for incidence of these, or any other, complications. METHODS: SLNBs were performed as they would be in the normal course of care, using fluoroscopic guidance and methodology established by a single radiologist overseeing the procedures. The radiologist's record of each visit was examined for note of immediate, postprocedural complications. The radiographs from the patients who received a single injection during their visit were examined to determine the position of the needle tip during the procedure. The needle-tip positions from the "Complications" and "No Complications" single injection cohorts were compared to determine if certain needle-tip positions cause less complications than others. RESULTS: Minor complications were encountered in 98 of the 1,777 total patient visits, for an overall complication rate of 5.5%. All complications were transient, and no patient suffered lasting harm. There were 1,232 procedures in which the patient received a single injection, and a minor complication was encountered in 62 of these visits. The complication rate approached 5% for all needle-tip positions, which is not statistically different from the overall complication rate. However, there was an increased likelihood of complications in patients undergoing a multiple injection procedure vs. those who had only one injection. CONCLUSIONS: Our results suggest that SLNBs performed with fluoroscopic guidance have a low incidence of complications. All of our complications were minor. The specific needle-tip position within or adjacent to the lumbar neural foramen does not appear to be associated with the incidence of complications.

Humans↗
PubMedDate not supplied

Cervical myelopathy. current diagnostic and treatment strategies.

Cervical myelopathy is a varied clinical syndromes resulting from spinal cord dysfunction. Underlying causes are numerous, but spondylosis at one or more levels is the most common etiology. Natural history studies have demonstrated a variable clinical course with gradual neurologic deterioration in a majority of patients. While prospective clinical comparisons are limited, existing literature suggests that operative management reliably arrests the progression of myelopathy and may lead to functional improvement in a majority of patients. The selection of surgical procedures must be carefully individualized based on specific clinical and radiographic factors. Whereas anterior decompression and fusion procedures at one or two motion segments have predictable results, procedures involving three or more levels are associated with increased morbidity. Newer techniques for the treatment of multilevel cervical myelopathy include anterior decompression with 360-degree fusion, hybrid corpectomy/anterior cervical discectomy and fusion techniques and the use of dynamic anterior cervical plates. An alternative technique for patients with a lordotic sagittal alignment is laminoplasty, which has a proven track record of long-term good to excellent results.

Cervical Vertebrae↗
PubMedDate not supplied

The effect of alendronate sodium on spinal fusion: a rabbit model.

BACKGROUND CONTEXT: Bisphosphonates affect bone remodeling and increase bone mass through the inhibition of osteoclasts. Their effect on osteoblasts, and the balance between osteoblastic and osteoclastic activity on bone turnover and healing, is not completely understood. Specifically, the effect of bisphosphonates on spinal fusion has yet to be determined. With the increasing use of bisphosphonates in the elderly population, this effect needs to be delineated. PURPOSE: To evaluate the effect of alendronate sodium after an intertransverse process spinal fusion in a rabbit model. STUDY DESIGN/SETTING: Randomized double-blinded in vivo study of the effect of alendronate sodium in a spinal fusion model. METHODS: Fifty New Zealand white rabbits underwent a posterolateral L5-L6 intertransverse process arthrodesis with autogenous iliac crest bone graft. The rabbits were then randomly divided into two groups. Group I received 3 cc of saline placebo per oral gavage, and Group II received 200 micrograms (approximately 0.05 mg/kg/day) of alendronate sodium dissolved in 3 cc of saline per day for 8 weeks. Upon completion, the rabbits were sacrificed and the lumbar spines harvested, radiographed and graded for motion across the fusion site with manual palpation. Two independent pathologists then prepared and sectioned each left and right fusion mass. Three random x10 fields were examined and graded for both the cephalad and caudad ends of each section (516 fields). Fusion quality was graded using an established histological scoring scale (score 0 to 7 based on fibrous and bone content of the fusion mass). RESULTS: Two rabbits died on the day of operation, and 48 rabbits survived the operation. Five additional rabbits died within the first 2 postoperative weeks. Thus, 43 rabbits (21 in Group I, 22 in Group II) completed the 8-week course of treatment. Grading each side separately, 26 of 42 fusion masses (62%) in Group I and 24 of 44 fusion masses (55%) in Group II had radiographic evidence of fusion (p=.76). With gross palpation, 11 of 21 motion segments (52%) in Group I versus 13 of 22 motion segments (59%) in Group II were determined to have a solid fusion (p=.76). Histologically, Group I had a higher median score (6.0; range, 0 to 7 vs. 1.0; range, 0 to 7; p<.0001) and a higher fusion rate (76% vs. 45%; p=.004) than Group II. CONCLUSIONS: Alendronate sodium appears to inhibit or delay bone fusion in a rabbit model. Presumably, this occurs as a result of uncoupling the balanced osteoclastic and osteoblastic activity inherent to bone healing. These findings suggest that a discontinuance of alendronate sodium postoperatively during the acute fusion period may be warranted.

Administration, Oral↗