Interbody Height Research Articles

Safety and Efficacy of Local Bone with PEEK Cage versus Iliac Bone Graft in Anterior Cervical Discectomy and Fusion: A Prospective Study

Introduction A prospective study was performed to compare the clinical and radiological results between the use of local bone graft with a PEEK cage versus an iliac bone graft in anterior cervical discectomy and fusion (ACDF). Materials and Methods A total of 60 consecutive patients who underwent ACDF were evaluated from January 2010 to January 2013. 29 patients received an ACDF with a PEEK cage combined with local bone graft (local bone cohort) and 31patients received an ACDF with tricortical iliac bone graft (iliac bone cohort). The intraoperative and perioperative complications of both cohorts were recorded. Preoperative and postoperative radiographs were taken to calculate the ratio of interbody height to the disc height and the interbody bony fusion rate. The Japanese Orthopedic Association (JOA) score and visual analogue scale (VAS) were used to estimate postoperative clinical outcomes. Results The mean follow-up time was 25.0 ± 3.8 months in the local bone cohort and 24.4 ± 3.4 months in the iliac bone cohort ( p = 0.56). Although there was no statistically significant difference between the two cohorts in terms of blood loss ( p = 0.17), the length of surgery was significantly less in the local bone cohort compared with that of the iliac bone cohort ( p = 0.01). Postoperatively, VAS scores were significantly decreased, and JOA scores were improved in both cohorts. However, no statistically significant difference was found between the two cohorts at final follow up ( p = 0.45, p = 0.93). The disc space height and segmental interbody angle at the surgical segment were greater in local bone cohort than those in the iliac bone cohort ( P < 0.001 and P < 0.001). The fusion rates were 93.1% (27/29) in local bone cohort and 90.3% (28/31) in the iliac bone cohort at last follow up ( p = 0.70). Perioperative complication rates in local bone cohort and iliac bone cohorts were 6.8% and 29%, respectively ( p = 0.04). Conclusions In a prospective study of 60 patients receiving ACDF with either local bone graft with a PEEK cage or an iliac bone graft alone, the former had a statistically shorter operation time, lower perioperative complications rate, and better radiological results. Although further long-term studies will delineate whether these improved radiographic findings will translate into better clinical outcomes, the local bone graft with a PEEK cage appears to be a safe alternative to the iliac bone graft during the perioperative period.

Early Clinical Outcomes and Radiographic Features After Treatment of Cervical Degenerative Disk Disease With the New Zero-Profile Implant: A 1-Year Follow-up Retrospective Study.

Retrospective study of 52 patients who underwent anterior cervical fusion with the new implant. To investigate the clinical outcomes and complications of the new implant for anterior cervical discectomy and fusion, and evaluate the radiographic features in the treatment of cervical degenerative diseases. Although high fusion rates can be achieved with the anterior cervical plate, plate-related morbidity affects the patient's satisfaction with the surgical outcomes. A retrospective study was performed in 52 consecutive patients who used the new implant at 106 levels. The clinical outcomes were evaluated preoperatively and postoperatively using the visual analog scale score for neck and arm pain and the Japanese Orthopedic Association and ASIA motor score for myelopathy preoperatively and postoperatively. The cervical curvature, the segment height, and fusion status were assessed on radiographs during a mean 12-month follow-up period. There was statistically significant difference in perioperative neck and arm visual analog scale pain score. The preoperative Japanese Orthopedic Association and ASIA motor scores were significantly lower than those before surgery (P<0.05), and this difference was maintained at the last follow-up. The occurrence of dysphagia was 11.5%, which was significantly lower than that reported in the previous literature. There was significant difference in lordosis before and after surgery (10.9±12.2 vs. 23.7±11.3, P<0.01) in the trisegmental group. The anterior disk height and interbody height of targeting segments increased from preoperative 5.1±1.56 and 31.9±3.43 to postoperative 9.1±1.02 and 36.7±2.44, respectively. Firm fusion was observed in all patients. Our investigations suggest that this new implant facilitates anterior cervical surgery with satisfactory clinical outcomes and a low rate of dysphagia. Our study has demonstrated that this new implant is able to restore and maintain physiological lordosis and segment height of the cervical spine postoperatively.

New Cage for Posterior Minimally Invasive Lumbar Interbody Fusion: a Study in Vitro and in Vivo

To design a new type of interbody fusion device made of nickel titanium NiTi shape memory alloy and to compare segmental stiffness after various posterior lumbar interbody fusion (PLIF) procedures in vitro and in vivo. Twelve sheep lumbar functional spinal units were randomly allocated to four groups. One acted as controls (N); the other three were treated with autogenous iliac crest bone dowel graft (L), a threaded cylindrical titanium (KC) interbody fusion device (TFC) or a new type of interbody fusion device made of NiTi shape memory alloy (NT) containing autogenous iliac crest graft. In addition, 15 sheep were allocated to three groups; one served as controls and the other two underwent TFC (KC) or NiTi-FC (NT). Nondestructive mechanical tests were performed in pure compression, extension, lateral bending and torsion. The operated spines were photographed regularly to assess changes in interbody height and degree of fusion. The animals were killed at 6 months for histologic testing. Biomechanical tests showed both the strength and axial stiffness of the NT and KC groups were significantly higher than those of the control group and L group (P < 0.05). When the mechanical performance in torque and torsion of each group were compared, the same results could be obtained. The maximal destructive load of the NiTi-TFC was 11 200 N and the safety coefficient was above 1.2. Radiological observations revealed that the bone callus around the interbody fusion device were gradually increased postoperatively (2 months, no obvious; 4 months, poorly define; 6 months, dense). The KC and NT group had lost 16% and 16.5% of their postoperative height but remained well above normal disc height (P < 0.05). Histologic examination showed new trabeculation connected with that of the host. The mechanical characteristics of the NiTi-TFC are excellent and it is safe and reliable.

Surgical Outcome of a Zero-profile Device Comparing with Stand-alone Cage and Anterior Cervical Plate with Iliac Bone Graft in the Anterior Cervical Discectomy and Fusion

ObjectiveA Zero-profile device is a cervical stand-alone cage with integrated segmental fixation device. We characteristically evaluated the radiological changes as well as clinical outcomes in the application of Zero-profile devices compared with stand-alone cages and anterior cervical plates with iliac bone grafts for the cervical disease.MethodsRetrospectively, total 60 patients at least more than one year follow-up were enrolled. Twenty patients were treated with Zero-profile devices (Group A), twenty patients with stand-alone cages (Group B) and twenty patients with anterior cervical plates and iliac bone grafts (Group C) for a single level cervical disease. The clinical outcomes were evaluated by Odom's criteria and Bazaz-Yoo dysphagia index. The radiologic parameters were by subsidence and the changes of the midpoint interbody height (IBH), the segmental kyphotic angle (SKA), the overall kyphotic angle (OKA) in index level.ResultsAlthough there was no significant clinical difference according to the Odom's criteria among them(p=0.766), post-operative dysphagia was significantly decreased in the Group A and B compared with the Group C (p=0.04). From the immediate postoperative to the last follow-up time, the mean change of IBH decrement and SKA increment were significant in the Group B compared with the Group A (p=0.025, p=0.033) and the Group C (p=0.001, p=0.000). The subsidence rate was not significant among all groups (p=0.338).ConclusionThis Zero-profile device is a valuable alternative to the anterior cervical discectomy and fusion with a low incidence of postoperative dysphagia and without segmental kyphotic change.

Endoscopic foraminal decompression preceding oblique lateral lumbar interbody fusion to decrease the incidence of post operative dysaesthesia.

BackgroundLumbar interbody fusion has become a well established method to diminish axial back pain as well as radiculopathy in patients with degenerative disc disease, stenosis, and instability. The concept of indirect decompression of the neural foramen and spinal canal while performing fusion became popular in the mid 1990’s with description of ALIF techniques. Morphometric analysis confirmed the extent of decompression of posterior elements with interbody height restoration. In an attempt to diminish potential complications associated with anterior or posterior approaches to the spine for interbody fusion, and with the hope of accomplishing fusion in a less invasive manner, lateral lumbar interbody fusion has become quite popular. This transpsoas approach to the disc space has been associated with a high incidence of neurologic complications. Even though this is the first technique to routinely recommend EMG monitoring to increase safety in the approach, neurologic injuries still occur. A newer oblique lateral lumbar interbody (OLLIF) approach has recently been described to lessen the incidence of neurologic injury. This technique also advocates use of EMG testing to lessen neurologic trauma. In spite of this precaution, neurologic insult has not been eliminated. In fact, even in patients whose electrical stimulation thresholds suggested a safe entry space into the disc, transient dysaesthesia continues to occur in 20-25 percent of cases.PurposeThis pilot study reflects data and observations of a subset of patients treated with endoscopic foraminotomy preceding oblique lateral lumbar interbody fusion (OLLIF) to assess specifically potential improvements in dysaesthesia rates.MethodsA select subset of patients undergoing OLLIF failed to meet electrodiagnostic criteria for safe disc access through Kambin’s triangle. These patients underwent an endoscopic foraminotomy and exiting nerve decompression prior to discectomy, endplate preparation and cage insertion.ResultsDysaesthesia did not occur in these patients whom otherwise would have likely been at risk for neurologic deficit.ConclusionsThese findings suggest that patients at risk for neurologic insult during oblique lateral lumbar interbody fusion can be protected by foraminoplasty.

Clinical and radiographic outcomes of cervical disc replacement with a new prosthesis

Background contextAnterior cervical discectomy and interbody fusion was a classical treatment for cervical degenerative disc disease (CDDD). However, the rigid fusion also leads to a reduction in normal cervical spine motion and to increased biomechanical stress at adjacent levels, which in turn accelerates degenerative changes of the discs at these levels. Cervical disc replacement (CDR) is a new technology with the aim of addressing the limitations of fusion procession and preserving motion at the treated level. Discover prosthesis (DePuy Spine, Raynham, MA, USA) is a new type artificial disc and there are few reports about it. PurposeThe purpose of this study was to analyze the primary clinical and radiographic outcomes of CDR with Discover prosthesis to treat mono- or bi-segment CDDD in a Chinese population. Study designThe study design was prospective and single-center clinical trial of the Discover prosthesis in the treatment of patients with mono- or bi-segment CDDD. Patients sampleSeventy-nine patients with 102 Discover prosthesis arthroplasty performed (56 mono-segment and 23 bi-segment) were evaluated. Outcome measuresClinical outcomes based on Japanese Orthopaedic Association (JOA), visual analog scale (VAS) pain score, and Odom's scale and radiographic outcomes including the anterior disc heights (ADH), posterior disc heights (PDH), range of motion, and performance of heterotopic ossification (HO) of the operative segment were assessed. MethodsClinical and radiographic follow-up was performed. Preoperative and postoperative ADH, PDH, and range of motion were measured from lateral and flexion-extension radiographs. The paired t test was used to assess the difference of clinical and radiographic outcomes before and after operation. The performance of HO was observed by two independent MD. ResultsThe mean follow-up time for all the patients was 31.6 months, ranging from 24 to 43 months. Mean preoperative JOA score was 9.5, and VAS overall pain score was 7.2. At 2-, 6-, 12-, and 24-month follow-up, the mean JOA score was 14.1, 14.7, 15.3, and 14.9, whereas the mean VAS overall pain score was 1.9, 1.7, 1.8, and 1.4, respectively. Mean JOA and VAS scores showed statistical improvements in the postoperative period. Seven patients had mild dysphagia within the first month after operation. According to Odom's scale, 52 patients had excellent outcomes, 25 patients had good outcomes, and 2 patients had fair outcomes at 2-year follow-up. The Mean preoperative ADH and PDH of the operative segment were 4.9 mm and 3.1 mm. Compared with preoperative, there were significantly increased and maintenance well at 2- (7.5 mm, 5.1 mm), 6- (7.5 mm, 5.0 mm), 12- (7.4 mm, 4.9 mm) and 24-month (7.2 mm, 5.0 mm) follow-up. Range of motion of the operative segment in the postoperative follow-up was slightly increased than the preoperative follow-up but not statistically significant. Heterotopic ossification was presented in six replaced levels at 1-year follow-up including 4 Grade I and 2 Grade II and 18 replaced levels at the follow-up more than 2 years including 8 grade I and 10 grade II. No prosthesis subsidence or excursion was identified. ConclusionsThe use of Discover prostheses in our study resulted in satisfactory clinical and radiographic outcomes. The prostheses can restore and maintain interbody height, while preserve the motion of the treated segment. Although the results of this study demonstrate initial safety and effectiveness in a Chinese population, we need further studies to know more about the impact of CDR with Discover prosthesis, especially on HO and adjacent segment degeneration.

Alternative grafts in anterior cervical fusion

ObjectiveThe present retrospective study was conducted to compare the clinical and radiographic outcomes in patients undergoing anterior cervical discectomy with fusion (ACDF) using carbon fiber reinforced polymer (CFRP) cages, or allograft. MethodsWe retrospectively reviewed cases of ACDF using allograft in 20 patients, and CFRP in 19 who had sequential radiographs before and after surgery, and at 1 year. ResultsThere were no apparent significant differences between the 2 groups in age (p=0.057), gender (p=0.635), or complications (p=0.648). At 12 months, there were no cases of construct failure, and fusion appeared to have been achieved in patients of both groups. Lordosis was increased significantly in both groups after surgery (p<0.001 in allograft and p=0.025 in CFRP), and was maintained up until 1 year (p<0.018 in allograft and p=0.05 in CFRP) without a difference between groups (p=0.721). Anterior interbody height was significantly increased (p<0.001 in both groups at each time points) after surgery, without a significant difference between groups (p>0.21). This increase in height was greatest in magnitude immediately after surgery, and declined with the passage of time. There was no detectable health-related quality of life difference between allograft and CFRP group after surgery (p>0.05). ConclusionThe present study demonstrates that CFRP cages appear to have comparable fusion rates, restoration of lordosis and disc space height, and complication rates to patients who undergo ACDF with allograft.

Anterior Cervical Discectomy and Fusion Using a Stand-Alone Polyetheretherketone Cage Packed with Local Autobone : Assessment of Bone Fusion and Subsidence

ObjectiveIt remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Cortical and subcortical bone from the anterior and posterior osteophytes of the segment could be used to fill the cage. The purposes of the present study are to evaluate the clinical outcomes and radiological outcomes including bone fusion and subsidence that occurred after anterior cervical discectomy and fusion using a stand-alone cage packed with local autobone graft.MethodsThirty-one patients who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage packed with local autobone graft from July 2009 to december 2011 were enrolled in this study. Bone fusion was assessed by cervical plain radiographs and computed tomographic scan. Nonunion was evaluated according to the absence of bony bridge on computed tomographic scan. Subsidence was defined as a ≥2 mm decrease of the interbody height at the final follow-up compared to that measured at the immediate postoperative period.ResultsSubsidence was observed in 7 patients (22.6%). Of 7 patients with subsidence greater 2 mm, nonunion was developed in 3. Three patients with subsidence greater 2 mm were related with endplate damage during intraoperative endplate preparation. Solid bone fusion was achieved in 28 out of 31 patients (90.3%).ConclusionWith proper patient selection and careful endplate preparation, anterior cervical discectomy and fusion (ACDF) using a stand-alone PEEK cage packed with local autobone graft could be a good alternative to the standard ACDF techniques with plating.

Improvement of sagittal balance and lumbar lordosis following less invasive adult spinal deformity surgery with expandable cages and percutaneous instrumentation

The treatment of adult spinal deformity (ASD) remains a challenge for the spine surgeon. While minimally invasive surgery (MIS) has many favorable attributes that would be of great benefit for the ASD population, improvements in lordosis and sagittal balance have remained elusive in cases involving the MIS approach. This report describes the evolution of an MIS method for treating ASD with attention to sagittal correction. Over an 18-month period 25 patients with thoracolumbar scoliosis were treated surgically. The mean patient age was 72 years, and 68% of the population was female. Patients were treated with multilevel facet osteotomies and interbody fusion in which expandable cages (mean 3.2 levels) were placed and percutaneous screw fixation (mean 5.3 levels) was performed. Seven patients underwent supplemental percutaneous iliac fixation. All patients underwent MIS without conversion to a traditional open procedure. The mean operative time was 273 mins and the mean blood loss was 416 ml. There were no intraoperative complications. The Cobb angle over the scoliotic deformity improved from a mean of 29.2° to that of 9.0° (p < 0.001). Lumbar lordosis between L-1 and S-1 improved from a mean of 27.8° to one of 42.6° (p < 0.001). Sagittal vertical axis improved from 7.4 cm to 4.3 cm (p = 0.001). Numeric pain scale scores improved as well, an average of 3.3 and 4.2 for the leg and back, respectively. A mean improvement of 20.8 points on the Oswestry Disability Index was seen at 12 months. Complications included: two cases requiring hardware repositioning, one case of screw pullout, one asymptomatic pedicle screw breach, prolonged hospitalization from constipation, and one acute coronary syndrome developing 3 days after surgery without myocardial damage. An expanding body of evidence suggests that sagittal balance remains a keystone for good outcomes after ASD surgery. Minimally invasive surgery that involves a combination of osteotomies, interbody height restoration, and advanced fixation techniques may achieve this goal in patients with less severe deformities. While feasibility will have to be proven with larger series and improved surgical methods, the present technique holds promise as a means of reducing the significant morbidity associated with surgery in the ASD population.

Fate of Posterior Osteophytes in Fused Segments After Anterior Cervical Discectomy and Fusion

Prospective cohort study. To investigate the fate of posterior osteophytes after anterior cervical discectomy and fusion (ACDF) using computed tomography. As a method of ACDF, indirect decompression through interbody height distraction and spontaneous posterior osteophyte resorption has the advantage of reducing complications that can occur during direct decompression. However, the outcome of resorption, of the posterior osteophytes, has not been considered to be satisfactory. Thirty-one patients underwent ACDF with plate fixation for cervical spondylotic radiculomyelopathy. The areas and lengths of the most prominent posterior osteophytes in each patient and the anteroposterior diameter of the intervertebral foramen were measured from computed tomographic images using commercial software. Among 31 patients, the posterior osteophytes decreased in 7 (23%), increased in 5 (16%), and were unchanged in 19 (61%). The mean change of area of prominent posterior osteophytes (ΔArea(5 years - 3 months)) was -0.42 ± 4.21 mm. There was no statistically significant change between Area(3 months) and Area(5 years) (P = 0.82). The mean change of length (ΔLength(5 years - 3 months)) was -0.02 ± 0.41 mm. There was no statistically significant difference between Length(3 months) and Length(5 years) (P = 0.84). The mean anteroposterior diameter of each intervertebral foramen of fused segments did not change significantly between 3 months and 5 years postoperatively on oblique foraminal images (C5 Rt. P = 0.31, Lt. P = 0.56; C6 Rt. P = 0.61, Lt. P = 0.49) and axial images (C5 Rt. P = 0.61, Lt. P = 0.49; C6 Rt. P = 0.71, Lt. P = 0.51). Contrary to previous reports, there was no evidence of consistent posterior osteophyte resorption during 5 years of follow-up.

Polyetheretherketone Cage filled with Beta-Tricalcium Phosphate versus Autogenous Tricortical Iliac Bone Graft in Anterior Cervical Discectomy and Fusion

Objective: To compare clinical and radiologic results of two graft materials for anterior cervical discectomy and fusion (ACDF) with rigid plate fixation for cervical spinal disorder. Methods: Twenty-eight patients treated with single-level ACDF with rigid plate fixation were retrospectively reviewed. They were divided into twogroups: Polyetheretherketone (PEEK) cage filled with beta-tricalcium phosphate (β-TCP) in Group A (n=15); and autogenous tricortical iliac bone graft in group B (n=13). The average follow-up durations were 16.3 months and 19.90 months for group A and group B, respectively. Clinical outcomes were graded using the visual analogue scale (VAS) score and neck disability index (NDI). Interbody height, segmental kyphotic angle and overall kyphotic angle were used as parameters to evaluate radiographic change in the 2 treatment groups. Results: Clinically, VAS scores and NDI significantly improved after the surgery in both groups (p 0.05). The fusion rates after 12 months in group A and B were 93.3% and 100%, respectively. One case of cage subsidence which resulted in pseudoarthrosis occurred in group A. However, statistical analysis did not show difference in fusion rate between the two groups (p>0.05). Conclusion: ACDF using PEEK cage filled with β-TCP showed comparable clinical and radiologic results with the standard of autogenous iliac bone graft. However, pseudoarthrosis did occur even with rigid plate and screw fixation in ACDF using PEEK cage filled with β-TCP. There is high likelihood of emerging pseudoarthrosis, especially when there is a sign of chronic and progressive cage subsidence.

Long term results of anterior cervical interbody fusion using coral bone spacer for cervical spondylosis

目的 研究珊瑚人工骨在颈前路手术中的愈合情况.方法应用珊瑚羟基磷灰石人工骨替代自体髂骨进行颈椎前路减压人工骨植骨融合钢板内固定手术180例(男126例、女54例),根据影像学资料,统计椎间隙高度、椎间角、颈前屈术前与随访时的变化.结果通过总结6年的随访结果,珊瑚人工骨得到了良好的愈合,使患者术后椎间隙高度、椎间角、颈前屈的纠正得到了的保持.结论珊瑚人工骨具有良好的愈合效果,可以达到和目体髂骨同样的临床作用。

Anterior cervical corpectomy and strut graft fusion using a different method

Background context: Strut graft fusion after corpectomy is frequently indicated for certain pathologies in the cervical spine. The “key-hole” technique and “dove-tail” technique are the popular methods used to insert the strut graft at present. Segmental collapse secondary to seating of the graft on cancellous bone and cord injury from placement or dislodgement the graft are our concerns. Our method was designed to solve these possible problems without affecting the arthrodesis. Purpose: To evaluate the results of this method that allows the graft to seat on both the hard end plate and cancellous bone of the upper and lower contacting vertebrae in a easy and safe way after varying levels of corpectomy in the cervical spine. Study design: A retrospective clinical and radiographic study conducted by an independent observer was performed on 23 patients treated with this different strut grafting method after cervical corpectomy, with at least 2 years of follow-up. Patient sample: A total of 23 patients from 1983 to 1994 underwent fusion using our strut grafting method with fibular allograft packed with autogenous bone. No augmented internal instrumentation was used in all these patients. The patients with an incomplete record or less than 2 years of follow-up were excluded beforehand. Outcome measures: Clinical outcome was assessed by a score based on three factors: neck pain, dependence on medicine and ability to return to work. The total score of these factors was seven. A score from 0 to 3 was defined as satisfactory, and a score from 4 to 7 was defined as unsatisfactory. The result of graft fusion, collapse of interbody height and loss of lordotic angle corrected by the graft were evaluated through the radiographic studies. Methods: The operative technique creates a notch in the anterior cortex and end plate of the respective superior and inferior vertebraes. Cylinder allograft filled with autogenous cancellous bone was used as bone graft for all patients. The bone graft is cut with corresponding pegs at both ends. The graft is inserted into the corpectomy space with the pegs inserted into the notches and the remainder of the graft placed onto the preserved superior and inferior bony end plates. Results: Twenty patients achieved successful fusion (87%). On average, the loss of anterior and posterior interbody height was 2.79 mm and 2.93 mm, respectively. The average loss of lordotic correction was 2.83 degrees. Eighty-three percent achieved satisfactory clinical outcomes. There were no neurologic injuries encountered during the operation. Partial graft dislodgment occurred in two patients (8.7%). Conclusions: This different method of strut grafting after cervical corpectomy has proven its safety and efficacy in its fusion and clinical results.

A new anterior cervical instrumentation system combining an intradiscal cage with an integrated plate: an early technical report.

To provide a technical report on a new device. Early outcome assessment of patients undergoing anterior cervical decompression and stabilization with the described technique. To detail the operative and technical aspects of the new anterior cervical instrumentation and to identify its suitability for an extensive clinical study. The controversy over the need for fusion in the surgery of cervical disc disease is in part fueled by the absence of an ideal technique. However, the design of the integrated anterior cervical plate and cage device (PCB) appears to provide immediate stability and to restore disc height and cervical lordosis in addition to reducing graft recipient and donor site-related complications. After a standard anterior cervical discectomy and preparation of the disc space, the correct size of the cage with integrated plate is inserted. Self-tapping screws are inserted without image intensifier. Cancellous bone chips are used. The technique was used in 29 patients that were followed prospectively from 5 to 24 months (median 8 months, interquartile range 6-15 months). The technique was easy to learn and implement. The authors' experience has been free of intraoperative complications. After surgery no screw backout or device failure was identified. Twenty-seven patients improved clinically. Donor site morbidity was trivial. No collars were applied after surgery. The design of the system appears to prevent bone-graft recipient site and donor site complications, provides immediate biomechanical stability, prevents screw backout or breakage, and restores posterior interbody height and lordosis. The device is of sufficient promise to warrant further close evaluation focusing on long-term outcome. The new radiolucent version has potential advantages for the assessment of fusion.

Ｃａｇｅ単独で行ったＬ５／Ｓ１後方進入腰椎椎体間固定術（ＰＬＩＦ）の治療経験

The purpose of this study was to evaluate the clinical outcome of posterior lumber interbody fusion (PLIF) with the interbody fusion cage for L5/S1. PLIF was performed on 18 patients consisting of 12 males and 6 females. 8 were diagnosed as disc degeneration, 7 as spondylolisthesis, 3 as spondylolytic spondylolisthesis. The average patients age was 38.2 years. The mean JOA score improved to 25.3 on the last follow-up from the preoperative score of 14.2. Posterior elements were preserved as much as possible, and two cages were then inserted into both sides.Low back pain and leg pain recurred in all patients. No breakage, displacement, backout of cage, progress of slipping, nor sinking was observed. In all cases, the interbody height was enlarged. Four cases showed clear zones less than 1mm around the cages. No motion was seen at the fusion level in all cases on dynamic radiographs.We believe that PLIF with interbody fusion cage for L5/S1 is useful for cases with diminished disc space.

On Some Points in the Treatment of Diabetes

<h3>ABSTRACT</h3> <h3>Study design</h3> Retrospective case series <h3>Objective</h3> Describe subsidence in lumbar interbody fusion using an expandable meshed allograft containment device with 12-month minimum radiographic follow-up. <h3>Background</h3> We have previously reported the use of a minimally invasive allograft-filled expandable meshed-bag containment system in the lumbar spine. Subsidence has not been reported with this device. <h3>Methods</h3> Consecutive adult patients that underwent 1- or 2-level interbody fusion with at least 1 year of follow-up were included in this study. Preoperative, postoperative, and final follow-up lumbar radiographs were analyzed to measure disc height at the anterior and posterior margins of the disc space, as well as the neuroforaminal height. <h3>Results</h3> Forty-one patients were identified, with a mean age of 63.4 years (± 11.8). A total of 61 levels were treated, with successful fusion observed in 54 levels (88.5%). The mean radiographic follow-up was 24.3 months (± 11.2). The mean disc height pre- and postoperatively was 6.9 mm (± 3.2) and 10.1 mm (± 2.9, <i>P</i> &lt; .001), respectively. The mean disc height at final follow-up was 8.3 mm (± 2.4). Average disc height subsidence was 1.8 mm (± 1.7, <i>P</i> &lt; .001). Overall, average disc height increased by a net 1.3 mm (± 2.5, <i>P</i> &lt; .001). The mean neuroforaminal height pre- and postoperatively was 18.0 mm (± 3.3) and 20.7 mm (± 3.6, <i>P</i> &lt; .001), respectively. The mean neuroforaminal height at final follow-up was 19.2 mm (± 3.4). Average neuroforaminal height subsidence was 1.3 mm (± 3.4, <i>P</i> = .012). Overall, average neuroforaminal height increased by a net 1.7 mm (± 2.8, <i>P</i> = .004). No significant difference in subsidence was observed between 1- and 2-level surgeries. <h3>Conclusion</h3> An expandable allograft containment system is a feasible alternative for lumbar interbody fusion. Due to its biologic and mechanical nature, the surgeon using such constructs should account for an anticipated average of 18% loss of interbody height due to subsidence during the bony remodeling/fusion process.