Polyetheretherketone Cage with Demineralized Bone Matrix Can Replace Iliac Crest Autografts for Anterior Cervical Discectomy and Fusion in Subaxial Cervical Spine Injuries

OBJECTIVE: This study aimed to compare the clinical and radiologic outcomes of patients with subaxial cervical injury who underwent anterior cervical discectomy and fusion (ACDF) with autologous iliac bone graft or polyetheretherketone (PEEK) cages using demineralized bone matrix (DBM). METHODS: From January 2005 to December 2010, 70 patients who underwent one-level ACDF with plate fixation for post-traumatic subaxial cervical spinal injury in a single institution were retrospectively investigated. Autologous iliac crest grafts were used in 33 patients (Group I), whereas 37 patients underwent ACDF using a PEEK cage filled with DBM (Group II). Plain radiographs were used to assess bone fusion, interbody height (IBH), segmental angle (SA), overall cervical sagittal alignment (CSA, C2–7 angle), and development of adjacent segmental degeneration (ASD). Clinical outcome was assessed using a visual analog scale (VAS) for pain and Frankel grade. RESULTS: The mean follow-up duration for patients in Group I and Group II was 28.9 and 25.4 months, respectively. All patients from both groups achieved solid fusion during the follow-up period. The IBH and SA of the fused segment and CSA in Group II were better maintained during the follow-up period. Nine patients in Group I and two patients in Group II developed radiologic ASD. There were no statistically significant differences in the VAS score and Frankel grade between the groups. CONCLUSION: This study showed that PEEK cage filled with DBM, and plate fixation is at least as safe and effective as ACDF using autograft, with good maintenance of cervical alignment. With advantages such as no donor site morbidity and no graft-related complications, PEEK cage filled with DBM, and plate fixation provide a promising surgical option for treating traumatic subaxial cervical spine injuries.

Usefulness of Anterior Cervical Interbody Fusion Using Locally Harvested Bone: Locally Harvested Bone Versus Autogenous Iliac Bone / 대한정형외과학회잡지

PURPOSE: The purpose of this study is to evaluate the usefulness of locally harvested bone in anterior cervical interbody fusion. MATERIALS AND METHODS: A retrospective review was conducted, including 31 patients who underwent anterior cervical interbody fusion using a polyetheretherketone (PEEK) cage and anterior plate fixation. We randomly divided the patients into two groups, local bone group and iliac bone group. In 15 patients of the local bone group, the cage was filled with locally harvested bone, and in another 16 patients of the iliac bone group, the cage was filled with autogenous iliac bone. RESULTS: Improvements in mean visual analogue scale (VAS) scores, from 5.8 and 7.7 to 1.6 and 2.3 for neck pain and arm pain, respectively, were observed in cases using locally harvested bone, while the improvements were from 5.7 and 7.2 to 1.4 and 2.2, respectively, in those using autogenous iliac bone grafts. However, no significant differences in mean VAS and neck disability index were observed between the two groups at the last follow up (p>0.05). Radiologic union was achieved at 14.0+/-2.50 weeks in the local bone group, and at 12.62+/-1.58 weeks in the iliac bone group. However, no significant difference was observed between the two groups (p=0.076). CONCLUSION: Utilization of locally harvested bone for packing in a PEEK cage for anterior cervical interbody fusion is considered a useful method because it gives satisfactory clinical results for retention of bone union and lordosis angles.

Subsidence of Polyetheretherketone Cage after Anterior Cervical Fusion / 대한정형외과학회잡지

PURPOSE: The purpose of this study is to evaluate the rate and direction of subsidence that occurred after anterior cervical discectomy and fusion using the polyetheretherketone (PEEK) cage and to analyze the risk factors of subsidence. MATERIALS AND METHODS: Thirty two patients (36 segments) who underwent anterior cervical discectomy and fusion using the PEEK cage and autologous cancellous iliac bone graft from July 2003 to November 2011 were enrolled in this study. anterior segmental height (ASH), posterior segmental height (PSH) and cage corner distance (CCD) were measured on plain radiographs. Subsidence was defined as > or =2 mm decrease in the average of ASH and PSH at the final follow up compared to that measured in the immediate postoperative period. A decrease of more than 3 mm was defined as severe subsidence for further statistical analysis. RESULTS: Subsidence of more than 2 mm was observed in 14 segments (38.9%) and severe subsidence (> or =3 mm) was observed in seven segments (19.4%). The direction of subsidence was examined by comparison of means of decreased ASH and PSH and anterior subsidence outweighed posterior subsidence (p<0.001). Examination of CCD showed that inferior subsidence was more frequent than superior subsidence (p<0.001, p=0.047). Among the suspicious risk factors for subsidence, intraoperative disc space distraction (anterior distraction: p=0.031, posterior distraction: p=0.007) and height of inserted cage (p=0.032) showed statistical significance. CONCLUSION: Considerable incidence of subsidence was observed after use of the cage. Using a cage of appropriate height and prevention of intraoperative over-distraction of disc space will be helpful to prevention of subsidence of the cage after anterior cervical discectomy and fusion using the PEEK cage.

ACDF Using the Solis Cage with Iliac Bone Graft in Single Level: Clinical and Radiological Outcomes in Average 36 months Follow-up

OBJECTIVE: To evaluate the utility of anterior cervical discectomy and fusion (ACDF) with polyetheretherketone (PEEK) cage and autograft through long term(average 36 months) follow-up. METHODS: Thirty selected patients (male:20/female:10) who suffered from cervical radiculopathy, myelopathy or radiculomyelopathy underwent a single level ACDF with PEEK cage and autograft from iliac crest from March 2006 to July 2008 in single institute. We followed patients for an average 36.4+/-8.1 months (ranged from 23 to 49 months). The Japanese Orthopedic Association (JOA) score for evaluation of myelopathy and visual analogue scale (VAS) for radiating pain was used to estimate postoperative clinical outcome. Plain x-ray on true lateral standing flexion, extension and neutral position view and 3D CT scan were used every 6 months after surgery during follow-up period. RESULTS: The mean VAS and JOA scoring improved significantly after the surgery and radiological fusion rate was accomplished by 100% 36 months after the surgery. We had no complication related with the surgery except one case of osteomyelitis. There was one case of Grade I fusion, four cases of grade II, and 25 cases of grade III by radiologic evaluation. CONCLUSION: This long term follow-up study for ACDF with PEEK cage shows that this surgical method is comparable with other anterior cervical fusion methods in terms of clinical outcomes and radiologic fusion rate.

Subsidence and Nonunion after Anterior Cervical Interbody Fusion Using a Stand-Alone Polyetheretherketone (PEEK) Cage

BACKGROUND: The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. METHODS: Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as > or = a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being > or = 2 mm in the interspinous distance on the flexion-extension lateral radiographs. RESULTS: The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 +/- 1.46 mm and 0.81 +/- 1.27 mm, respectively. Subsidence > or = 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). CONCLUSIONS: Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.

Efficacy of Posterior Lumbar Interbody Fusion using PEEK Cage and Pedicle Screw Stabilization in Degenerative Lumbar Spinal Disorders: Minimum 3 Years Follow up Results

STUDY DESIGN: A retrospective study. OBJECTIVES: To evaluate the three-plus year follow-up results of patients who underwent posterior lumbar interbody fusion with PEEK cage and pedicle screw fixation for lumbar degenerative disease. SUMMARY OF LITERATURE REVIEW: There are few previous reports addressing posterior lumbar interbody fusion using PEEK cage with mid-term follow up periods. MATERIALS AND METHODS: 260 patients who underwent posterior lumbar interbody fusion with PEEK cage and pedicle screw fixation for lumbar degenerative disease were enrolled. We classified patients into three groups according to their fusion level: group A (n=151) had one-level fusion, and group B (n=91) had two-level fusion, and group C (n=18) had three-level fusion. Clinical outcomes were evaluated by pre- and post-operative Visual analogue scale (VAS) scores, the Oswestry Disability Index (ODI), and complication and reoperation rates. Radiologic outcomes were measured by the fusion rate, sagittal alignment, disc height and changes. RESULTS: VAS (pre-operative to final follow-up) changed from 7.62+/-2.03 (5-10) to 3.19+/-1.94 (1-8) in group A, from 6.83+/-2.28(4-9) to 4.51+/-2.18(2-9) in group B and from 7.17+/-2.46 (5-10) to 4.63+/-1.97(1-9) in group C. Final follow-up ODI also decreased in group A (17.6+/-8.56%), group B (15.4+/-5.46%) and group C (24.7+/-7.46%). This corresponds to scores of 94.7% in group A, 92.3% in group B and 94.4% in group C. There were significant differences between preoperative, post-operative and final follow-up lumbar lordosis [p=0.042(group A), 0.036(group B), 0.045(group C)], segmental lordosis [p=0.036(group A), 0.039(group B), 0.047(group C)]. Reoperation was performed in patients 8 group A, 4 group B, and 1 group C, and there is no significant diffrence between groups. Adjacent segmental change was found in all reoperation patients, but showed no correlation with clinical results. CONCLUSIONS: Posterior lumbar interbody fusion with PEEK cage and pedicle screw fixation in lumbar degenerative disease showed excellent clinical results and fusion rates, regardless of patient fusion levels.

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 (beta-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 (p0.05). 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 alpha-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 beta-TCP. There is high likelihood of emerging pseudoarthrosis, especially when there is a sign of chronic and progressive cage subsidence.

Comparison between Carbon Fiber Composite Frame and PEEK(Polyetheretherketone) Cages in the Efficiency of Interbody Fusion for Surgical Treatment of Cervical Disc Diseases

OBJECTIVE: To evaluate the efficiency of carbon fiber composite frame and polyetheretherketone(PEEK) cages in the interbody fusion for surgical treatment of cervical disc diseases, we analyzed fusion time and subsidence rate. METHODS: From March 2004 to February 2007 fifty patients with cervical disc diseases underwent anterior discectomy and interbody fusion in 60 levels. The subjects were 26 men and 24 women with a mean age of 57.2 years ranging from 29 to 67. Among them 25 patients underwent operations using carbon fiber composite frame cages (Osta-Pek(R), Co-Ligne, Zurich, Switzerland) in 30 levels, and 25 patients using PEEK cages(Cornerstone(R), Medtronic, TN, USA) in 30 levels. The cages were packed with allograft bone or bone substitute(demineralised bone matrix). On lateral flexion-extension radiographs anterior disc height and posterior disc height were measured at preoperative time, postoperative 1, 3, 6 and 12 month respectively. Segmental stability(lordotic angle) was measured at postoperative 3, 6, and 12 months in all 60 levels for fusion time. RESULTS: The anterior disc height and posterior disc height were 4.87+/-1.36mm and 3.25+/-0.73mm at preoperative time, 7.32+/-1.41mm and 4.77+/-0.80mm at postoperative 1month, and 5.87+/-1.47mm and 3.22+/-0.93mm at posto- perative 12 months respectively in carbon fiber composite frame cage group(30 levels). The anterior disc height and posterior disc height were 4.88+/-1.18mm and 3.75+/-0.75mm at preoperative time, 7.26+/-1.17mm and 5.27+/-0.55mm at postoperative 1month, and 6.23+/-1.16mm and 3.96+/-0.69mm at postoperative 12months respectively in PEEK cage group(30 levels). The angular motion at the fused segment was measured in carbon fiber composite frame cage and PEEK group for segmental stability(two degrees or less flexion-extension range of motion at the fusion site). The carbon fiber composite frame cage group was stabilized between postoperative 3 months and 6 months, but PEEK cage group was stabilized between 6 months and 9 months. This result was statistically significant(p-value =0.003)(Fig. 2). Fusion rate of carbon composite frame cage group was 28%, 67% and 83% at 3, 6, 12 months after operation, and that of PEEK cage group was 24%, 48% and 86% at postoperative 3, 6 and 12 months respe- ctively. Complications included transient hoarseness, cage migration and subsidence. There was no persistent hoar- seness or Horner syndrome. We have observed severe subsidence(above 3mm) in two cases(6.7%) of carbon fiber composite frame cage group only. Anterior cage migration was shown in each one case(3.3%) of carbon fiber composite frame and PEEK cage group. CONCLUSION: The carbon fiber composite frame cage group showed a tendency of earlier fusion than PEEK cage group but both cages were same in the fusion rate at postoperative 1 year. But, restoration or maintenance of inter- vertebral height was much better in PEEK cage group than carbon fiber composite frame cage group. Subsidence rate was higher in carbon fiber cage group rather than PEEK cage group.

Radiological and Clinical Comparison of 1 Cage versus 2 Cages for Posterior Lumbar Interbody Fusion with PEEK Cage and Local Bone Graft / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study. OBJECTIVES: We wanted to compare and evaluate the results of using one cage and two cages with local bone grafting for each segment when performing posterior lumbar interbody fusion (PLIF). Summary of Literature Review: Some authors have reported that unilateral one-caged PLIF with local bone grafting and posterior instrumentation was no difference from bilateral two-caged PLIF regard to the fusion rates and the radiologic or clinical results. MATERIALS AND METHODS: From March 2005 to February 2006, PLIF was performed on 36 patients who had lumbar degenerative disease. They were categorized as the cases for which one cage was used for a segment and the cases for which 2 cages were used for a segment. The clinical and radiological results in each group were compared. RESULTS: There was complete union in 11 segments with using one cage (55%), complete union in 12 segments using two cages (77%) and incomplete unions in 9 segments with using one cage (45%) and incomplete union in 4 segments with using 2 cages (25%), and there wasn't any case of nonunion (p>0.05). The postoperative changes of the intervertebral disc space were a 2.0 mm increase with using one cage and a 2.2 mm increase with using two cages, yet these values decreased by 0.4 mm and 0.3 mm, respectively, on the last follow-up. The mean operation time was 89 minutes for one segment with one cage and 105 minutes for one segment with two cages. The blood loss was a mean of 602 ml with one cage and 802 ml with two cages (p<0.05). There was no significant difference between the one cage group and the two cages group for the Kirkadly-Willis criteria. CONCLUSION: Posterior decompression and PLIF with one PEEK cage for treating degenerative lumbar disease was more effective for the operation time and the amount of blood loss than that with two cages, but the fusion rate, the alteration of the intervertebral disc space, the improvement of pain and the clinical results were no different. However, these results are from short term follow up, so continuous follow up will be necessary in the future for assessing the long term prognosis.

Posterior Lumbar Interbody Fusion Using New Hydroxyapatite Block: Comparison with Metal and PEEK Cages / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study OBJECTIVES: This study compared the clinical outcomes of posterior lumbar interbody fusion (PLIF) using hydroxyapatite blocks with PLIF using a metal or poly-ether-ether-ketone (PEEK) cage. SUMMARY OF THE LITERATURE REVIEW: There are few reports on the clinical outcomes of PLIF using a hydroxyapatite block for treating lumbar degenerative disease. MATERIALS AND METHODS: The 27 PLIF cases (62 units, HA block) that were followed up for 1-year were compared with 13 cases using a metal cage and 13 cases using a PEEK cage. Pedicle screw fixation was performed for all the cases. If the local bone is deficient, then an additional bone graft with autogeous iliac bone or bone substitute was used. The visual analog scale(VAS) for low back pain and radiating pain, the Oswestry disability index (ODI), the intervertebral height and the halo sign around the cages and pedicle screws were comparatively analyzed. RESULTS: The mean VAS score for low back pain before PLIF and using the HA block, the metal cage and the PEEK cage was 7.5, 8.3 and 6.2, respectively, and this was 3.3, 2.9 and 4.8 after PLIF (P0.05, One-way ANOVA). CONCLUSION: PLIF using a HA block showed improvements, including the back pain, and the ODI was satisfactory and this didn't fall below those ODIs of using metal or PEEK cages. Although a HA block may have higher tendency to break, there was no breakage at the 1-year follow up.

Radiologic Assessment of Subsidence in Stand-Alone Cervical Polyetheretherketone (PEEK) Cage

OBJECTIVE: Aim of study was to find a proper method for assessing subsidence using a radiologic measurement following anterior cervical discectomy and fusion (ACDF) with stand-alone polyetheretherketone (PEEK), Solis(TM) cage. METHODS: Forty-two patients who underwent ACDF with Solis(TM) cage were selected. With a minimum follow-up of 6 months, the retrospective investigation was conducted for 37 levels in 32 patients. Mean follow-up period was 18.9 months. Total intervertebral height (TIH) of two fused vertebral bodies was measured on digital radiographs with built-in software. Degree of subsidence (DeltaTIH) was reflected by the difference between the immediate postoperative and follow-up TIH. Change of postoperative disc space height (CT-MR DeltaTIH) was reflected by the difference between TIH of the preoperative mid-sagittal 2D CT and that of the preoperative mid-sagittal T1-weighted MRI. RESULTS: Compared to preoperative findings, postoperative disc height was increased in all cases and subsidence was observed only in 3 cases. For comparison of subsidence and non-subsidence group, TIH and CT-MRDeltaTIH of each group were analyzed. There was no statistically significant difference in TIH and CT-MR DeltaTIH between each group at 4 and 8 weeks, but a difference was observed at the last follow-up TIH (p=0.0497). CONCLUSION: ACDF with Solistrade mark cage was associated with relatively good radiologic long-term results. Fusion was achieved in 94.5% and subsidence occurred in 8.1% by the radiologic assessment. Statistical analysis reveals that the subsidence seen later than 8 weeks after surgery and the development of subsidence does not correlate statistically with the change of the postoperative disc space height.

The Results of Posterior Lumbar Inter-body Fusion using PEEK Cage andPedicle Screw Stabilization in Degenerative Lumbar Spinal Disorders / 대한정형외과학회잡지

PURPOSE: To evaluate the results of posterior lumbar interbody fusion (PLIF) using PEEK cage with local laminectomized bone and pedicle screws stabilization in multiple segment degenerative lumbar spinal disorders. MATERIALS AND METHODS: We performed a retrospective analysis (1 yr follow-up examination) on 152 patients with PLIF using PEEK cage. The 152 patients, were sub-categorized as follows: 1) group A - one level fusion (80 cases), 2) group B - two level fusion (60 cases), and 3) group C - three level fusion (12 cases). We compared each group based on operation time, amount of bleeding, number of complications, sagittal alignment, fusion rate, adjacent segment problems, and evaluation of the clinical result as per the criteria in Kim et al (1991). RESULTS: For operation time group A took 190.25+/-40.89 min, group B took 230.46+/-39.13 min, and group C took 243.25+/-39.13 min (p=0.08). Furthermore, amount of bleeding for group A was 1,140+/-704 ml, group B was 1,328+/-776 ml, and group C was 1,688+/-756 ml (p=0.07). Consequently, no significant difference was observed between each group. For lumbar lordosis, segmental lordosis, anterior and middle disc height, the last follow-up value was significantly greater than the preoperative value in all three groups. For the adjacent segmental problem, group A had 6 cases, group B had 6 cases, and group C had 2cases. The clinical result revealed a good result in 93.25% for group A, 91.67% for group B, 91.67% for group C. In addition, the fusion rate was 93.75% for group A, 95.00% for group B, and 91.67% for group C. Moreover, the number post-operative complication cases for group A totaled 2 postoperative infections with metal loosening, 5 non-union, and 2 hematomas. Group B had 1 postoperative infection with metal loosening, 3 nonunion, 1 dural tear, and 1 incomplete root injury. Lastly, in group C, 1 complete root injury occurred. CONCLUSION: A PLIF using PEEK cage with local laminectomized bone and posterior pedicle screw stabilization in multiple segments should be considered to be a useful surgical method as a result of favorable clinical results and a fusion rate similar to the rate of a single segment.