“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusion” Dr. Donald W. Kucharzyk Dr. Michael Trainor Crown Point, Indiana, USA

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions”  Originally described for Pott’s disease  Cloward was the first to show its use in the treatment of low back pain  Lumbar interbody arthrodesis has become the treatment of choice for disabling low back pain  Graft placement is favorable for fusion being placed in compression and having a good vascular disc space

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  Anterior lumbar interbody fusion’s have been performed for many years  The goals have been to re-establish disc space height,the correction of malalignment, re-establish normal neuroforaminae, and achieve a solid arthrodesis  Autograft as well as allograft have been used in the past to achieve these goals

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions”  Graft material available include both allograft and autograft  Forms of allograft graft material include: rings, wedges, and cortical dowels  Autograft exists in the form of iliac crest wedges

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  Autograft was the gold standard for interbody fusion with favorable outcome studies  Allograft in the form of wedges, rings or dowels have also performed well with decreased complications  “Kanayama et al”: reported the superiority of allograft versus autograft in terms of strength and stability

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  Recent advancements in spine fusion technology has lead to the development of titanium cages  These new devices have shown biomechanical stability via reduced spinal segmental motion with arthrodesis  “Tsantrizos et al”: revealed in a study of ALIF constructs that cages reduced spinal motion similar to auto or allografts

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  A review of the published orthopaedic literature has revealed no study directly comparing allograft versus metallic interbody cages  A study was undertaken to randomly assess the results comparing anterior interbody fusion via femoral ring allograft versus a metallic interbody cage

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  Twenty patients with the diagnosis of one level spondylotic herniated nucleus pulposis with instability and radiculopathy were randomized  Two study groups were developed in which one received a femoral ring allograft (GROUP 1) and the other a BAK titanium metal cage (GROUP 2) with both receiving autogenous iliac crest graft

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions”  Patients were evaluated for average age, gender, average follow-up, risk factors, preoperative instability, operative time, blood loss, radiographic fusion, reconstruction of the disc height, migration of the graft, segmental lordosis, and revision rates

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions” INDICATIONS  Internal Disc Disruption  Post-Laminectomy Syndrome  Discogenic Instability  HNP with Instability (similar to the study pool indications of Kuslich et al and Ray et al)

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions” FUSION CRITERIA  Severe, disabling, intratable back pain  Symptoms for at least a year  Failure of conservative treatment  No previous arthrodesis at target level  Absence of degeneration at next level  Loss of disc height and instability (similar to criteria of Ray et al)

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  Average age : 52.3 yrs (range 32 to 58)  Gender: males: 8 females: 12  Average Follow-up: 4 yrs (3yrs to 5yrs)  Operative Time: GROUP 1: 63 minutes GROUP 2: 73 minutes range of time: minutes

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  Average Blood Loss: 50cc (range )  Risk factors: 10 patients were smokers  Preoperative Pain Levels: Disabling: 8 Marked: 8 Moderate: 4

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  Preoperative Instability: assessed on lateral flexion/extension radiograph to compare motion of the individual segment  Average Motion: 12 degrees range was from 10 to 24 degrees

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS PREOPERATIVE AND POSTOPERATIVE SEGMENTAL LORDOSIS (measured on a standing lateral) GROUP 1 GROUP 2 Preop: 3 deg. Preop: 5 deg. Postop: 16 deg. Postop: 11 deg.

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS RESTORATION OF DISC HEIGHT (measured preop, postop, and at follow-up) GROUP 1 GROUP 2 Preop: 2mm 5mm Postop: 8mm 9mm FU (2yrs) 7mm 6mm lost hgt. 4/11 4/9 maintained 7/11 5/9

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS DEPTH OF GRAFT PLACEMENT (measured posterior vertebral body to graft) GROUP 1 GROUP 2 6.2mm 7.7mm

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS GRAFT MIGRATION (measured posterior vertebral body to graft) GROUP 1 GROUP 2 1mm in 4 of 11 2mm in 4 of 9

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS SUBSIDENCE OF GRAFT (comparision preop and postop placement) GROUP 1 GROUP 2 1mm in 3 of 11 3mm in 4 of 9

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS POSTOPERATIVE MOTION (flexion/extension lateral radiograph) GROUP 1 GROUP 2 no change 7 of 11 no change in 5 of 9 4 deg. In 4 of 11 8 deg. In 4 of 9

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  Radiographic Fusion Criteria -range of motion on flexion/extension lateral of less than 2 degrees -postoperative migration of 1mm or less -no radiolucent lines

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  McAfee et al IMAST 2001 reported in the original BAK study of motion 7 degrees or less, migration of 2mm or less, and a 2mm lucent line as acceptable for fusion  Later the criteria was changed to 3 degrees, still 2mm migration and 2mm lucent line

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions”  Criteria for fusion was reviewed recently by McAfee et al “Critical Discrepancy: A Criteria for Successful Arthodesis following Interbody fusion”  Discrepancies exist in criteria for fusion  BAK Study: 5 degree’s  Ray et al (1997): 7 degree’s  BAK article Spine 1998: 3 degree’s

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions”  Zdeblick et al: “ A Prospective Randomized Study of Lumbar Fusion” Spine 1993 established the criteria that should be applied to all fusions whether anterior, posterior, or 360 degree approach  Criteria was: 2 degree’s of motion on F/E  This was the criteria we adapted in our review of the data for this study

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS  Fusion criteria was much more stringent in our study pool  Fusion failure was therefore defined as motion on F/E lateral radiograph, lucent line, collapse and subsidence, migration of the graft, and severe pain with functional limitations

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS RADIOGRAPHIC FUSION RESULTS GROUP 1 GROUP 2 Our Criteria 73% 56% BAK Study 93% 86%

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL RESULTS REVISION RATES GROUP 1 GROUP 2 3 of 11 4 of 9 27% 44%

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL CASE FEMORAL RING ALLOGRAFT

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL CASE BAK CAGE

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL CASE FEMORAL RING FAILURE

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CLINICAL CASE BAK FAILURE

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CONCLUSION  Femoral ring allograft group re-established disc heights better than the BAK group  Segmental lordosis was better re-established in the femoral ring allograft group than the BAK group  Subsidence was less in the femoral ring allograft group than the BAK group

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CONCLUSION  Motion was seen in both groups but was greater in the BAK group  Graft migration was seen in both groups but was greater in the BAK group  Revision rates were higher in the BAK group than the femoral ring allograft group

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions” CONCLUSIONS  Difference in fusion rates Femoral Ring versus BAK stems from the fact that the Femoral Ring pool was a complete discectomy versus the BAK which was partial reamed channel discectomy  Similar to a study by McAfee et al IMAST 2001

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Lumbar Fusions” CONCLUSIONS  Complete discectomy offer higher fusions rates than partial reamed channel discectomy due to more surface area, less avascular disc material remaining, better orientation, and restoration of disc height  Complete discectomy should be performed when utilizing any interbody device

“A Controlled Randomized Outcome Study of Femoral Ring Allograft versus BAK Instrumentation in Anterior Interbody Fusions” CONCLUSION  Finally, based upon the results of this study, the traditional more cost effective femoral ring allograft technique of interbody lumbar fusion performed comparably well next to the newer BAK technology

THANK YOU Dr. Donald W. Kucharzyk The Orthopeadic, Pediatric & Spine Institute