Rationale for Interbody Fusion With Threaded Titanium Cages at Cervical and Lumbar Levels. Results on 357 Cases

Summary ? Study Design. Retrospective analysis of 357 cases of degenerative disc disease treated by interbody fusion with threaded titanium cages.  Objective. To determine the safety and efficiency of cervical and lumbar interbody fusions using threaded titanium cages and autogenous bone.  Summary of Background Data. Stabilizing the anterior column by interbody fusion, though reported over 50 years ago, is less commonly done than posterior fusions. The recent development of rigid cages housing autogenous bone simplifies the technique of interbody fusion. This report shows our combined results using this technique.  Materials and Methods. One hundred thirty-five patients had cervical fusions at 175 levels between C3 and C7. Two hundred twenty-two patients had lumbar fusion at 243 levels between L2 and S1. All surgeries involved one or two disc spaces except for one three level cervical fusion. We implanted all disc spaces with threaded cages containing autogenous bone.  Results. In the cervical area, 95% of the radiculopathic patients had a good to excellent result, but only 50% of the myelopathic patients did so. At lumbar level, 80% of the patients were classified as good to excellent, 15% improved but remained disabled, 5% had minimal or no improvement. The cervical fusion rate was 90% at 6 months and 100% at one year. Lumbar fusion rate was 91% at one year and 96% at 2 years. No late breakage or cage displacement occurred.  Conclusions. Cervical and lumbar interbody fusions with threaded titanium cages appear to be efficacious with few complications. Long term follow-up (4 years cervical, 7 years lumbar) confirms that impression.     

Translaminar facet joint screws to enhance segmental fusion of the lumbar spine

Summary From 1984 to 1988, 70 consecutive lumbar and lumbosacral spine fusions enhanced with translaminar facet joint screws were performed for segmental degenerative disease. Twenty patients had partial decompression of central stenosis, 15 concomitant discectomy, and 19 lateral nerve root decompression. The mean time to fusion was 4.5 months (range 2–7 months). At follow-up (average 45 months; range 24–74 months) 98.5% were judged to have solid fusion. Satisfactory results were observed in 84% of cases, 91% without previous surgery and 75% after previous discectomy. Supplementation of posterolateral fusion by translaminar facet screws significantly improved time to fusion, fusion rate, and clinical outcomes with no significant increased complications.     

Facet fusion in the lumbosacral spine: a 2-year follow-up study

OBJECTIVE: A clinical and radiological follow-up study was undertaken to assess the safety, efficacy, and complication rate associated with instrumented facet fusion of the lumbar and lumbosacral spine. METHODS: This study involved 99 patients with degenerative lumbar disorders who were treated surgically at the authors' neurosurgical department and followed for more than 2 years. Eighty-two patients underwent one-level fusion for the treatment of Grade I or II degenerative spondylolisthesis and accompanying spinal canal stenosis (44 patients) or recurrent disc herniation (38 patients). Seventeen patients underwent two-level fusion for the treatment of either double instances of the above indications (seven patients) or concurrent stenosis at the adjacent level (10 patients). RESULTS: There were no technique-related complications. The overall 2-year success rate of fusion was 96%; the success rates by fusion type were 99% in one-level fusions and 88% in two-level fusions. Degenerative spondylolisthesis had the highest success rate at 100%, whereas the success rate in patients who had not responded to previous discectomy was 93%. Patients with concurrent stenosis experienced the lowest success rate: 80%. Excellent or good clinical results were obtained for 85% of patients with one-level fusions and for 65% of patients with two-level fusions. CONCLUSION: Instrumented facet fusion alone is a simple, safe, and effective surgical option for the treatment of patients with single-level disorders, especially patients with degenerative spondylolisthesis.     

Computed tomography-guided percutaneous facet screw fixation in the lumbar spine. Technical note

The authors describe a new minimally invasive technique for posterior supplementation using percutaneous translaminar facet screw (TFS) fixation with computed tomography (CT) guidance. Oblique axial images were used to determine facet screw fixation sites. After the induction of local anesthesia and conscious sedation, a guide pin was inserted and guided with a laser mounted on the CT gantry. Cannulated TFSs were placed via a percutaneous approach. From December 2002 to August 2003, 18 patients underwent CT-guided TFS. In 17 of these patients this procedure was supplementary to anterior lumbar interbody fusion, which had been performed several days earlier; in the remaining patient, CT-guided TFS fixation was undertaken as the primary therapy. Twelve patients had painful degenerative disc disease or unstable degenerative spondylolisthesis, three had infections, and three had deformities. All screws were inserted accurately and there were no complications. This new minimally invasive surgical technique may offer an alternative to pedicle screw fixation as a method of posterior supplementation.     

Risk factors for adjacent segment disease after lumbar fusion

The incidence of adjacent segment problems after lumbar fusion has been found to vary, and risk factors for these problems have not been precisely verified, especially based on structural changes determined by magnetic resonance imaging. The purpose of this retrospective clinical study was to describe the incidence and clinical features of adjacent segment disease (ASD) after lumbar fusion and to determine its risk factors. We assessed the incidence of ASD in patients who underwent lumbar or lumbosacral fusions for degenerative conditions between August 1995 and March 2006 with at least a 1-year follow-up. Patients less than 35 years of age at the index spinal fusion, patients with uninstrumented fusion, and patients who had not achieved successful union were excluded. Of the 1069 patients who underwent fusions, 28 (2.62%) needed secondary operations because of ASD and were included in this study. In order to identify the risk factors, we matched a disease group and a control group. The disease group consisted of 26 of the 28 patients with ASD, excluding the 2 patients for whom we did not have initial MRI data. Each patient in the disease group was matched by age, sex, fusion level and follow-up period with a control patient. The assumed risk factors included disc and facet degeneration, instability, listhesis, rotational deformity, and disc wedging. The mean age of the 28 patients with ASD requiring surgical treatment was 58.4 years, which did not differ significantly from that of the population in which ASD did not develop (58.2 years, p = 0.894). Of the 21 patients who underwent floating fusion, only 1 developed distal ASD. Facet degeneration was a significant risk factor (p < 0.01) on logistic regression analysis. The incidence of distal ASD was much lower than that of proximal ASD. Pre-existing facet degeneration may be associated with a high risk of adjacent segment problems following lumbar fusion procedures.     

Unilateral transforaminal posterior lumbar interbody fusion.

A prospective analysis of consecutive patients who had lumbar fusion using the unilateral transforaminal posterior lumbar interbody fusion with pedicle screw fixation is presented to assess the clinical and radiographic outcomes of the transforaminal posterior lumbar interbody fusion procedure and describe the technique and indication in the treatment of degenerative disease of the lumbar spine. Forty patients treated with transforaminal posterior lumbar interbody fusion for degenerative diseases of the lumbar spine (with anterior column deficiency) were followed up for a minimum of 3 years (mean, 3.4 years; range, 3-3.9 years). Radiographic assessment included plain and flexion and extension radiographs. Clinical outcome was based on pain relief, ability to do activities of daily living, and return to work. Thirty-six patients (90%) had solid fusions and at latest followup, segmental lordosis has increased in all patients. Eighty-five percent of patients had excellent or good clinical outcome(s). The unilateral transforaminal posterior lumbar interbody fusion provides bilateral anterior column support through a unilateral approach. The patients had high fusion rates and patient satisfaction as reported with similar complications found in other methods commonly used for spinal decompression and stabilization.     

Long-Term Results in Patients Treated with Posterior Instrumentation and Fusion for Degenerative Scoliosis of the Lumbar Spine

Summary  The authors report a homogeneously investigated and surgically treated series of 4 0 patients with degenerative scoliosis of the lumbar spine. The series included 22 females and 18 males with a mean age of 62.8 years. The clinical presentation, the diagnostic work-up, the indication for surgery, the surgical techniques and results are reported. Final evaluation was possible in 30 patients at a mean period of observation of 59.5 months. Following a very precise diagnostic and therapeutic protocol excellent, good and satisfactory surgical results were obtained in 13 (43.3%), 16 (53.3%) and 1 (3.3%) patients, respectively. While scoliosis was converted from a mean preoperative Cobb angle of 18.7° to 7.6° mean pre-operative lumbar lordosis was slightly augmented from 37° to 41.5°. The results suggest that maintainance or correction of lumbar lordosis is more important than the conversion of the scoliotic deformity which is probably treated sufficiently by partial correction and stabilization.  Observation over time indicates that the degenerative cascade evolves despite internal fixation and fusion in the majority of the patients until a stable state is reached. This stable state is probably rather the result of ankylosis of the facet joints than the effect of posterolateral fusion.     

Transforaminal lumbar interbody fusion: clinical and radiographic results and complications in 100 consecutive patients

OBJECTIVE: We retrospectively reviewed the results of 100 consecutive transforaminal lumbar interbody fusions (TLIFs) performed at one institution. The preoperative diagnoses included degenerative disk disease (55), spondylolisthesis (41; 22 isthmic, 19 degenerative), and degenerative adult scoliosis (4). There were 64 single-level, 33 two-level, 2 three-level, and 1 four-level TLIF (140 levels). METHODS: The fusion mass was assessed by an independent observer using biplanar radiography, whereas clinical outcomes were assessed by means of several established outcome measures. RESULTS: By level, the posterolateral fusion was judged to be probably or definitely solid in 78% of levels, whereas the interbody fusion was radiographically solid in 88% of levels, for an overall 93% fusion success/patient (94%/level). All patients had >24 months of postoperative clinical follow-up, and 82 patients (82%) were available for outcome measure assessment at an average follow-up of 34 months (range 24-61 months) postoperatively. Eighty-one percent of these patients reported a >50% decrease in their symptoms, and 76% of patients were satisfied with their results to the degree that they would have the procedure again. However, a large percentage of patients experienced incomplete relief of their symptoms. Twenty patients sustained minor complications, and there were no major complications. CONCLUSIONS: We conclude that TLIF is a safe and effective method of achieving lumbar fusion with a 93% radiographic fusion success and a nearly 80% rate of overall patient satisfaction but frequently results in incomplete relief of symptoms. Complications resulting from the procedure are uncommon and generally minor and transient.     

Closed loop instrumentation of the lumbar spine

A review of 40 consecutive nonreported multilevel lumbar fusions revealed an unacceptable pseudarthrosis rate of 32.5%. In an attempt to reduce this complication, a modification of segmental spinal instrumentation with use of a closed loop was performed on 50 consecutive patients treated by multilevel lumbar stabilizations. The primary diagnoses were degenerative disc and/or facet disease in 32, spondylolisthesis in 14, and pseudarthrosis in four. Thirty-eight percent had three or more levels to be fused. Thirty-two percent had had previous spinal surgery. Follow-up study was a minimum of one year. Seventy-three percent had posterior facet fusions. Twenty-seven percent had bilateral transverse process fusions. A pseudarthrosis occurred early in six patients, an incidence of 12%; three of the six occurred in patients with spondylolisthesis. Four of the six pseudarthroses occurred following posterior fusions. Subjective symptoms were improved in 80%. Working capacity was the same or better in 56%. Closed loop instrumentation (CLI) decreased the overall incidence of pseudarthrosis. When combined with transverse process fusion, CLI produced a slightly higher rate of success (90%) than did posterior fusion alone (87%) but did not reduce the incidence of pseudarthrosis in patients with spondylolisthesis.     

Extension CT scan: its suitability for assessing fusion after posterior lumbar interbody fusion

Posterior lumbar interbody fusion (PLIF) is a popular procedure for treating lumbar canal stenosis with spinal instability, and several reports concerning fusion assessment methods exist. However, there are currently no definitive criteria for diagnosing a successful interbody fusion in the lumbar spine. We suggested evaluating fusion status using computed tomography (CT) in extension position to detect pseudoarthrosis more precisely. The purpose of this study was to evaluate its usefulness for determining bone union quality after PLIF. Eighty-one patients who underwent PLIF at 97 levels were retrospectively enrolled. The study population included 48 men and 33 women (mean age 58.9 years, range 21–85 years). Patients were followed up for more than 12 months after surgery. The mean follow-up period was 27.6 months (range 14–49 months). Fusion status was evaluated using three ways: flexion–extension radiographs, CT images in flexion and extension position. In the flexion–extension radiographs, mobility of more than 3°, a remaining clear zone, or an uncertain bone connection constituted an incomplete union. For CT images, a remaining clear zone, a gas pattern, or an uncertain bone connection constituted an incomplete union. Flexion–extension radiographs demonstrated a solid fusion in 90.7% of the 97 levels at 10.7 months postoperatively. When fusion was demonstrated on flexion–extension radiographs, the rate of fusion affirmed by flexion CT and extension CT was 87.6 and 69.1% of the levels assessed, respectively. The rate of pseudoarthrosis detected on extension CT images was significantly higher than that on flexion–extension radiographs (P < 0.001) and flexion CT (P < 0.01). The rate of fusion achieved on extension CT was 85.6% at 15.1 months postoperatively. Extension CT could detect pseudoarthrosis more clearly than flexion–extension radiography and flexion CT. The CT images are influenced by body position and dilating anterior disc space in extension CT contributes to detect pseudoarthrodesis. Thus, extension CT was a useful method for assessing fusion status after PLIF.     

The efficacy of direct current electrical stimulation to enhance canine spinal fusions

A prospective experimental study was devised to examine the effect of direct current electrical stimulation on the healing of lumbar spinal fusions. Twelve mongrel dogs had posterior facet fusion bilaterally at L1-L2 and L4-L5. A direct current electrical stimulator was placed through each facet fusion. One-half of the electrodes were functional, while the remainder served as controls. Two animals were killed at two and four weeks, and four animals were killed at six and 12 weeks, postoperatively. Each facet fusion was evaluated using high-resolution roentgenograms and routine histology. In the two-, four-, and six-week specimens, there was little difference in the roentgenographic or histologic appearance of the control and stimulated fusions. However, by 12 weeks, all eight stimulated facet joints showed roentgenographic and histologic evidence of solid bony fusion, but none of the eight control facet joints demonstrated osseous bridging of the fusion site. The results of this study suggest that direct current electrical stimulation appears to enhance the bony union of facet fusions in the canine lumbar spine.     

Unilateral transforaminal posterior lumbar interbody fusion (TLIF): indications, technique, and 2-year results

A prospective analysis of consecutive cases of lumbar fusion using the unilateral transforaminal posterior lumbar interbody fusion (TLIF) technique with pedicle screw fixation. The objective of the study was to assess the clinical and radiographic outcome of TLIF and describe the technique and indications in the treatment of degenerative disease of the lumbar spine. Forty patients treated with TLIF for degenerative diseases of the lumbar spine were followed up for a minimum of 2.5 years (mean: 36 months; range: 30-42 months). Twenty-three patients had degenerative disc disease alone, 13 had associated isthmic or degenerative spondylolisthesis, and 4 had recurrent disc herniations at the L4-L5 level. Thirty-six (90%) had solid fusions radiographically at latest follow-up. Seventy-nine percent had excellent or good clinical outcomes. Our patients demonstrated high fusion rates and patient satisfaction.     

Anterior lumbar fusion using a hybrid interbody graft

Summary This is a radiographic report of 40 patients (20 men, 20 women) who underwent anterior lumbar interbody fusions (73 levels) utilizing a “hybrid” interbody graft composed of femoral cortical allograft (FCA) bone and iliac crest cancellous autograft bone. The average age at surgery was 38 years (range 17–64 years), and follow-up averaged 1.4 years (range 1.0–2.4 years). Nineteen of the patients had undergone previous lumbar surgery. Thirty-two patients (63 levels) underwent anterior fusion combined with some type of posterior fixation, and eight patients (10 levels) had no posterior fixation. Types of posterior fixation included: for 20 patients (36 levels) Steffee variable screw placement fixation, for 10 patients (23 levels) translaminar facet screws (TFS), for 1 patient (3 levels) Knodt rods and for 1 patient (1 level) facet screws. Based on the persistence of lucent lines at the graft-host interface, three patients (one level each) were felt to have non-unions at their latest follow-ups at 1.4, 1.5 and 2.0 years, respectively. Two of these patients had no posterior fixation, and the other had TFS fixation. The overall fusion rate was 96% (70 of 73 levels). The fusion rate for all levels treated with posterior fixation was 98% compared with 75% for those without fixation. Intervertebral disc heights (IVDH) were measured on all films and corrected for magnification with computer assistance. On average, the IVDH was increased postoperatively but returned to preoperative values at follow-up. IVDH loss was independent of the type of instrumentation used. No complications arose from the use of the hybrid graft. Incorporation of the allograft portion of the graft is slow and was felt to be complete in only 7 of the 73 levels at follow-up. We conclude that the hybrid interbody graft technique is a safe and reliable method for performing anterior lumbar interbody fusions and should be combined with some type of posterior fixation. Long-term follow-up will be required to assess the behaviour of the allograft until incorporation is complete.     

Retrospective study of 77 patients harbouring lumbar synovial cysts: Functional and neurological outcome

Summary Background. Synovial cysts represent an uncommon and probably underestimated pathological entity of the degenerative lumbar spine. The authors report a retrospective analysis of the clinical presentation, radiological studies and operative findings in 77 patients surgically treated for symptomatic lumbar synovial cysts at their institution. Materials and method. Between January 1992 and June 1998, a total of 77 patients presenting with symptomatic lumbar synovial cysts were operated on in the author’s department. Operative procedure, complications, results and pathological findings were correlated with preoperative assessment. There were 41 men and 36 women with an average age of 63 years (range 44–90 years). Results. On the basis of their symptom complex on presentation, two populations were identified: patients who presented with a single radicular pain (group I = 51 patients), and patients who presented with bilateral neurogenic claudication (group II = 26 patients). Neurological examination on presentation demonstrated motor deficit (12%), sensory loss (26%) and reflex changes (35%). Degenerative disc disease and facet joint osteoarthritis was a frequent finding in patients with pre-operative MRI. Facet joint orientation was >45° in 76.6% of patients. Preoperative spondylolisthesis was found in 48% on radiological studies. All the patients were treated surgically with resection of the cyst. No fusion was performed as a first line procedure. However subsequent fusion was necessary in one patient who developed symptomatic spondylolisthesis. Mean follow-up period was of 45 months ranging from 18 to 105 months. Only one recurrence occurred during the follow-up period. An excellent or good functional outcome was seen in 97.4% of cases, and 89% of the patients with motor deficit recovered. Conclusions. Surgical resection of lumbar synovial cysts is an effective treatment associated with very low morbidity. Synovial cysts are associated with increased grade and frequency of facet joint asteoarthritis but not with increased grade or frequency of degenerative disc disease compared with patients without cysts. In the author’s opinion, at the present time, there is no reliable criterion which allows the development of a symptomatic spinal instability to be predicted in patients with a preoperative spondylolisthesis and therefore fusion as a first line procedure is still debatable.     

关节突自体骨移植后路腰椎间盘植骨融合固定术的临床分析

目的探讨关节突自体骨移植后路腰椎间盘植骨融合固定术治疗椎间盘退变的远期疗效。方法自2001年10月至2007年10月本组收治腰椎退变病人50例(平均53.2岁),用这一方法进行椎间融合,平均随访3年。用日本矫形协会标准(JOA)评分:痊愈率、并发症和X线片的结果进行综合的评定。结果关节突自体骨移植后路腰椎间盘植骨融合固定术,椎间融合率(92.0%),临床效果(JOA评定治愈率78.3%),在治疗椎间盘退变、椎体滑脱锥体骨折取得了良好的效果,术后有3个病人出现了并发症。结论关节突自体骨移植后路腰椎间盘植骨融合固定术治疗椎间盘退变疾病手术疗效满意,显著提高融合率,预防神经根管狭窄、神经卡压的发生,减少术后断钉和椎体滑脱复发等问题。     

Radiological follow-up of the degenerated facet joints after lateral lumbar interbody fusion with percutaneous pedicle screw fixation: Focus on spontaneous facet joint fusion

BackgroundLateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion.MethodsWe retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints’ fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively.ResultsThe fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade ≧ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion.ConclusionsOur study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.     

Union versus nonunion after posterolateral lumbar fusion: a comparison of long-term surgical outcomes in patients with degenerative lumbar spondylolisthesis

It has been reported that in patients undergoing posterolateral lumbar fusion (PLF), the fusion status is not related to the short-term operative results. To determine whether the fusion status influences the long-term operative results of PLF, we retrospectively examined the surgical outcomes of uninstrumented PLF for a minimum of 8 years (average, 9.5 years), by comparing cases exhibiting union with those exhibiting nonunion. Uninstrumented PLF was performed for the treatment of lumbar canal stenosis (LCS) with degenerative spondylolisthesis. Since nine patients were lost to final follow-up, the study included 42 patients, and the follow-up rate was 82.4%. The mean age of the patients was 64.1 years (range 46–77 years). Eight patients exhibited fusion at the L3–4 level and 34 patients, at the L4–5 level. The fusion status was assessed using plain radiographs. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scores. Nonunion was noted in 26% (11/42) of the patients. There were no statistically significant differences between the groups exhibiting union and nonunion with respect to age, sex, preoperative JOA score, or preoperative lumbar instability. The union group achieved better operative results than the nonunion group at the 5-year and final follow-up (P = 0.006 and 0.008, respectively) although there was no significant difference in the percent recovery at 1 and 3-year follow-up (P = 0.515 and 0.506, respectively). A stepwise regression analysis revealed that the best combination of predictors for percent recovery at the time of final follow-up included the fusion status and the presence of comorbid disease. The results indicate that the fusion status following PLF is a critical factor influencing the long-term but not short-term operative results in the treatment of LCS with degenerative spondylolisthesis.     

Surgical management of lumbar spinal stenosis

Eighty consecutive patients with lumbar spinal stenosis surgically treated during a 5-year period by the author were reviewed. Patients were placed in the following categories: lateral spinal stenosis (10), central-mixed stenosis (29), spinal stenosis after laminectomy and/or fusion (32), and spinal stenosis with degenerative scoliosis (9). Contrast-enhanced computed tomographic (CT) scans were helpful in determining the levels requiring decompression. However, in the multiply operated patient, contrast-enhanced CT scans were misleading in six patients. Patients with lateral spinal stenosis were treated with unilateral laminectomy and partial facetectomy. The 29 patients with central-mixed stenosis underwent decompressive laminectomy and bilateral facetectomies. Six fusions were done. In the nine patients with spinal stenosis and scoliosis, concaveside partial facetectomies and laminectomies were done as well as spinal fusions. The 32 patients with spinal stenosis after previous laminectomy and spinal fusions were the most difficult group to analyze, and their treatment was the least standardized. There were 19 good, eight fair, and five poor results in those who had undergone previous surgery. Fifty-seven of the 80 patients (71%) experienced a good result from their surgical treatment.     

Radiographic fusion rate after implantation of facet bone dowels

Background contextAchieving a posterolateral fusion in conjunction with performing decompressive laminectomies can prevent recurrence of stenosis or worsening of spondylolisthesis. Facet bone dowels have been introduced and marketed as a less invasive alternative to pedicle screws. Surgeons have been placing them during lumbar laminectomy surgery and coding for intervertebral biomechanical device and posterolateral fusion. These bone dowels have also been placed percutaneously in outpatient surgery centers and pain clinics for facet-mediated back pain.PurposeTo describe fusion outcomes in patients who underwent facet bone dowel placement.Study design/settingRetrospective analysis of a single center's experience.Patient sampleNinety-six patients comprise the entire cohort of patients who underwent facet bone dowel implantation at our institution with adequate postoperative imaging to determine fusion status.Outcome measuresFusion rates as determined on postoperative computed tomography (CT) scans and dynamic lumbar X-rays if CT is not available.MethodsThreaded facet bone dowels in this study were placed according to the manufacturer's recommended methods. The bone dowels were placed after open exploration of the facet complex or percutaneously through a tubular retractor on the contralateral side from a microdiscectomy or synovial cyst resection. The most recent available postoperative imaging was reviewed to determine fusion status.ResultsOf 96 patients in our series, 6 (6.3%) had a fusion seen on CT and 4 did not exhibit any movement on dynamic lumbar X-rays for a total fusion rate of 10.4% (10/96). Eighty-six (89.6%) patients were shown on imaging to not have a solid fusion either by visualizing a patent facet joint on CT or measurable movement between the flexion and the extension lumbar X-rays.ConclusionsThis article is mainly intended to question whether the implantation of facet bone dowels can produce a solid fusion radiographically. In our experience, the placement of facet bone dowels does not equal the time, skill, or attention to detail that is necessary for a posterolateral lumbar arthrodesis, and our follow-up radiographic studies clearly demonstrate an inadequate fusion rate.     

The translaminar approach to canalicular and cranio-dorsolateral lumbar disc herniations

Summary. Summary.   Introduction: The interlaminar approach is the standard procedure for most disc herniations in lumbar spine surgery. However, in cranially extruded disc herniations including canalicular herniations, partial or complete facetectomy is necessary with increased risk of postoperative spinal instability. We present the translaminar technique which allows a more direct and less destructive operative approach.   Methods: 30 patients using the translaminar fenestration were analysed by a postoperative follow-up of 6 weeks and one year. The mean-age was 57.2 years. For resection of the disc herniation, a small round or oval fenestration (6–8 mm) in the hemilamina, craniomedially to the facet joint, was performed. No patient received a partial or total facetectomy.   Results: The majority of affected discs were at the L4-L5 level (53%). An extruded fragment was found in 28 patients (93%). In 5 patients bleeding from epidural veins complicated the intra-operative course. In 50% the nerve root was visually exposed. 15 patients (50%) had an intervertebral discectomy additional to the fragment excision.  One patient was re-operated on after 10 days because of persisting radicular pain by using the same translaminar approach. 28 patients showed complete or nearly complete relief of radicular pain. Using this approach we have seen no major complication or clinical instability during a follow-up of at least one year.   Conclusions: The translaminar approach is an effective and minimally invasive technique in both canalicular and cranio-dorsolateral disc herniations. It gives an additional possibility to avoid partial removal of the facet joints, can be performed in all lumbar segments and preserves structures important for segmental spinal stability. The approach allows access to the extruded disc fragment and intervertebral disc space comparable to classical approaches and is a frequently used operative technique in our department.