Purpose of the Study

Assessment of long term results of Chemonucleolysis vs. surgery for soft disc herniation

Purpose

To compare the efficacy and safety of balloon kyphoplasty (BKP) to non-surgical management (NSM) over 24 months in patients with acute painful fractures by clinical outcomes and vertebral body kyphosis correction and surgical parameters.

Purpose

Lumbar paraspinal muscle dysfunction and low back pain are strongly correlated. Muscle atrophy is common in LBP and is recognised by MRI scan. Corticosteroid injections and physical rehabilitation programs are advocated for treatment of LBP.

The purpose is to evaluate efficacy of specific lumbar multifidus muscle retraining exercises and perifacet multifidus injections in treatment of Low Back Pain (LBP) and referred leg pain.

Objective

To identify any difference in clinical outcome between Intra-Capsular facet (IF) and Peri-facet (PF) injections in patients with low back pain (LBP). IF and PF joint steroid injections have been used for treatment of LBP with varied reports of pain relief for many years.

Balloon kyphoplasty (BKP) is a minimally invasive treatment for vertebral fractures (VCF) aiming to correct deformity using balloon tamps and bone cement to stabilize the body. Patients with 1 - 3 non-traumatic acute VCF were enrolled within three months of diagnosis and randomly assigned to receive either BKP (N=149) or nonsurgical care (N=151). Follow-up was 2 years.

The mean SF-36 physical component summary (PCS) score improved 5.1 points (95%CI, 2.8-7.4; p<0.0001) more in the kyphoplasty than the nonsurgical group at one month, the primary endpoint of the study.

Kyphoplasty improved the PCS score by an average of 3.0 points (95%CI, 1.6-5.4; p=0.002) during the two-year follow-up. There was a significant interaction between treatment and follow-up time (p=0.003), indicating that the treatment effect over the year is not uniform across follow-up; a result from early improvement that persists in the kyphoplasty group whereas the nonsurgical group shows more incremental improvement over time.

Overall, patients assigned to kyphoplasty also had statistically significant improvements over the two years compared to the control group in global quality of life (EQ-5D), pain relief (VAS), back disability (RMDQ) and days of limited activity (within a two-week period).

There was no statistical significant difference between groups in the number of patients with adverse events or new VCF's over 24 months.

Compared to the control, BKP improved quality of life and reduced back pain and disability and did not increase adverse events including the risk of new vertebral fractures over 2 years.

Assessment of long term results of Chemonucleolysis vs. surgical enucleation in soft disc herniation

From 1982 to 1985, 100 patients with symptomatic disc herniation were randomly allocated to receive either Chemonucleolysis or disc enucleation after all these patients had a trial of conservative treatment for three months.

The outcome of result was measured using MacNab Criteria with the help of

Questionnaire

Assessing the patients in clinic

44 patients out of original 100 patients were followed up in the clinic 25 years later. 24 were from chemonucleolysis group and 20 from the surgical group.

According to MacNab criteria 62.5% had excellent or good results and 25% poor results in chemonucleolysis group and in surgery group 70% had excellent or good results and 10% poor results. Patients with poor result in Chemonucleolysis group consisted of: a) 1 had poor result post TKR, b) 4 were offered surgical enucleation subsequent to failed Chemonucleolysis though they did not seem to benefit from surgery and 1 out of these 4 also had fibromyalgia. c) 1 had poor result after sustaining fracture neck of femur. Poor results in surgical group were due to persistent back pain.

The results at 25 year follow-up have shown no statistically significant difference between the patients treated by either chemonucleolysis or surgery. The added benefit of using the chymopapain injection is that it is of lower cost. Chemonucleolysis should have a wider role in treatment of intervertebral disc herniation.

Background

Vertebral body compression fractures (VCFs) impair quality of life (QOL) and increase patient morbidity and mortality. The international, multicentre, randomised, controlled Fracture Reduction Evaluation (FREE) trial was initiated to compare effectiveness and safety of Balloon kyphoplasty (BKP) to non-surgical management (NSM) for the treatment of acute painful VCFs. We describe the primary endpoint of the ongoing 2-year study.

Purpose: Correlation of clinical outcome of X stop interspinous process decompression in patients with symptomatic lumbar spinal stenosis is made with spinal canal area change on positional MRI.

Method and Results: Clinical outcome was assessed by ZCQ, ODI, SF36 and VAS scores. There is clinically significant improvement if two ZCQ domains improved > threshold or patients were satisfied. Dural sac area was measured standing erect and sitting, neutral, flexion and extension preoperatively and at 2 years. Increased dural sac area was taken as radiological improvement.

Thirty-six patients had MRI at 2 years. Using paired t test we noted statistically significant increase in mean dural sac area in all four positions mentioned above. There was clinical improvement in 26 and some or no improvement in 10 patients. Number with increase in canal cross sectional area was 28 and that with reduced area was 8. Clinical and canal area improvement was seen in 20 (56%) patients and clinical improvement with reduced canal area was seen in 5 (14%). Some or no clinical improvement with canal area improvement occurred in 8 (22%) patients and no significant clinical or canal area improvement in 3 (8%).

Conclusions:

Majority of patients (56%) showed clinical and cross sectional area improvement at 2 years.

Interest statement: Commercial/industry support: Medtronics

Purpose: Correlation of the clinical outcome of X stop interspinous process decompression (IPD) in patients with symptomatic lumbar spinal stenosis (LSS) is made with their preoperative disc heights.

Method: 45 patients, who had clinical follow-up at 2 years, had pre-operative erect positional MRI scans. Clinical outcome was assessed by Zurich Claudication Questionnaire,ODI,SF36 and VAS scores.ZCQ is the most condition specific for LSS and was used. There is clinically significant improvement if two ZCQ domains improved > threshold (SS> 0.46, PF> 0.42, PS< 2.4) or patients were satisfied. Disc heights were measured in the standing erect posture. Osiris 4.17 software program was used for measurements. Statistics used was Chi-Square test with cross tabulation.

Results: There was clinical improvement in 33 and some or no improvement in 12 patients. Overall preoperative range of disc heights was 1.8 to 10.05 mm, median 5.93. Disc height was less than or equal to 5mm in 21 patients and it was > 5 mm in 24 patients.19 patients who had initial disc height of > 5 mm and 14 patients who had disc height of less than or equal to 5 mm had clinically significant improvement. In the group of patients who had some or no improvement the numbers were 5 and 7 respectively. We found a difference between the groups with bigger and smaller preoperative disc heights and a larger proportion of patients with bigger preoperative disc height had better clinical outcome. This difference was not statistically significant, P = 0.350.

Conclusions: The X stop device remains clinically effective at the end of 2 years in the majority of patients. Overall patients who had bigger preoperative disc heights 79% (i.e. 19/24 who had > 5mm initial disc height) had better clinical outcome compared to those with smaller preoperative disc heights.

Interest statement: Commercial/industry support: Medtronics

Background: The X stop interspinous process decompression device has been used effectively in symptomatic lumbar spinal stenosis. It holds the spinal segment in a flexed position maintaining increase in dural sac and foraminal areas.

Aim: To study the effect of X-stop on the lumbar spine kinematics at 24 months post operatively at the instrumented and adjacent levels.

Design: Prospective Observational Study of 48 patients.

Methods: Patients had a positional MRI scan preoperatively, 6 and 24 months post operatively in erect, flexion, extension and neutral positions. Disc heights, endplate angles, segmental and lumbar spine motion were measured at stenosed instrumented and adjacent levels. Osiris 4.17 software program was used for measurements. The data was analysed using paired t test on SPSS ver.15.01.

Results: 48 patients underwent scans preoperatively. At 2 years 40 patients were scanned (3 patients had removal of X stop and 5 were not scanned). Of these, 38 scans were complete. Mean anterior disc height reduced from 7.2 mm to 5.9 mm (p< 0.001) at 24 months at the instrumented level. There were no significant changes in posterior disc height at instrumented or adjacent levels. The mean lumbar spine motion was 22o and 20o (p=0.366) in single level cases and 24.5o and 22.8o (p=0.547) in double level cases preoperatively and at 24 months. There was no significant change in the segmental range of motion at instrumented or adjacent levels.

Conclusion: X-stop device does not significantly alter the kinematics of lumbar spine at instrumented or adjacent levels at 24 months postoperatively.

Purpose: Balloon kyphoplasty (BKP) is a minimally invasive treatment for acute vertebral compression fractures (VCF) that aims both to correct associated vertebral deformity (reduce) and stabilize the fracture by injecting bone cement. We performed the first multicenter randomized trial to assess the effect of BKP.

Method: Patients with 1–3 non-traumatic vertebral compression fractures diagnosed within 3 months were randomly assigned to receive either BKP (N=149) or usual nonsurgical care (NSC) (N=151). Measurements of quality of life, back pain and function, days of disability and bed rest were assessed at baseline, 1, 3, 6 and 12 months.

Results: The primary outcome measure, the difference between groups in change from baseline scores in the physical component summary of the SF-36 questionnaire, improved 3.5 points (95% CI, 1.6 to 5.4; p=0.0004) more in the BKP group when averaged across 12 months of follow-up. Compared with the NSC group, those assigned to BKP also had greater improvement in quality of life and back function throughout 12 months of follow-up as measured by the EuroQol and Roland-Morris scales; a difference of 0.14 points (95% CI, 0.05 to 0.23; p=0.0023) more and 3.2 points (95% CI, 1.7 to 3.8; p< 0.0001) and reported fewer days of limited activity in the previous 2 weeks due to back pain (2.5 fewer days; 95% CI, 1.2 to 3.8; p=0.0001). New radiographically detected vertebral fractures occurred in 41.8% of subjects in the kyphoplasty and 37.8% in the nonsurgical group (4% difference; 95% CI −7.5 to 15.6; p=0.5).

Conclusion: Compared to nonsurgical treatment, balloon kyphoplasty improved multiple measurements of quality of life, back pain and disability that last at least one year after the procedure. No difference is seen between groups in radiographically detected VCF’s (Clinicaltrials.gov number, NCT00211211).

Background: X stop interspinous decompression device has been used effectively in symptomatic patients with lumbar canal stenosis. The positional MRI scanner images patients in the erect weight bearing position and is used here to evaluate the efficacy of the X stop in maintaining increase in dural sac and foraminal areas.

Aim: To assess the clinical effectiveness of X stop in patients with lumbar canal stenosis and measure its effect in decompressing the spinal canal two years postoperatively.

Design: Prospective Observational Study.

Methods: Clinical outcome was assessed by ZCQ, VAS, ODI and SF36 questionnaires. Clinical and radiological outcomes were measured preoperatively and at 2 years. Foraminal area was measured in flexion and extension whereas dural sac area was measured in erect, neutral, flexion and extension. Osiris 4.17 software program was used for the measurements. The data was analysed using paired t test on SPSS ver.15.01.

Results: With ZCQ overall 57% of patients had clinically significant improvement at 24 months. The mean ODI and VAS scores showed improvement. The SF-36 improved in four domains. Radiologically we noted increase in mean dural sac area in all positions. There was a small increase in foraminal areas and statistically significant increase in dural sac areas at 24 months.

Conclusion: The X stop device remains clinically effective at the end of 2 years. It is a relatively less invasive procedure without major complications and can be performed as a day case procedure. X stop maintains increase in dural sac and foraminal areas at 24 months postoperatively.

Introduction: Deep Venous Thrombosis (DVT) and pulmonary embolism (PE) cause significant morbidity and mortality in orthopaedic surgical practice, although the incidence following surgery to the lumbosacral spine is less than following lower limb surgery. Our objective was to compare our rate of thromboembolic complications with those published elsewhere and investigate whether the adoption of additional pharmacological and physical measures had reduced the incidence of clinically evident deep venous thrombosis (DVT) and pulmonary embolism (PE).

Materials and Method: This study was undertaken to investigate the incidence of DVT/PE during the 10 years from 1/1/1985 to 31/12/1994, and then to assess the effectiveness of an anticoagulant policy introduced during 1995 using low dose aspirin or LMH in high risk cases. All records for spinal operations were reviewed for thromboembolic complications by reference to the Scottish Morbidity Record form SMR1. To ensure that all patients were compliant with the policy, data for the whole of 1995 was omitted and the period 1/1/1996 to 31/12/2003 was taken to assess its effectiveness.

Surgery was done with the patient in the kneeling, seated prone position which leaves the abdomen free and avoids venous kinking in the legs.

Results: Records of a total of 1111 lumbar spine operations were performed from 1/1/1985 to 31/12/2004 were reviewed. The overall incidence of thromboembolic complications was 0.29%. A total of 697 operations were performed from 1/1/1985 to 311994 with two cases of DVT and no cases of PE giving thromboembolic complication rate of 0.29%. During the period 1/1/1996 to 31/12/2003, 414 operations resulted in one case of DVT and no cases of PE, a rate 0f 0.24%.

Conclusion: The incidence of thromboembolic complications is low whether or not anticoagulation is used. We believe that the kneeling, seated prone operating position is a significant contributing factor.

Background: Balloon kyphoplasty is a minimally invasive treatment for acute vertebral fractures that aims to reduce and correct vertebral deformity by inserting expandable balloon tamps and then stabilize the body by filling it with bone cement. The effect of balloon kyphoplasty on quality of life has not been tested in a randomized trial.

Methods: Patients with up to 3 non-traumatic acute vertebral compression fractures were enrolled within 3 months of diagnosis and randomly assigned to receive either balloon kyphoplasty (N=149) or usual nonsurgical care (N=151). Measurements of quality of life, back pain and function, and days of disability and bed rest and spine radiographs were assessed through 12 months of follow-up.

Results: Compared with those assigned to nonsurgical care, participants assigned to balloon kyphoplasty had 5.2 points (95% CI, 2.9 to 7.4; p< 0.0001) greater improvement in the physical component of the SF-36 quality of life questionnaire at one month and 1.5 points (95% CI, − 0.8 to 3.8; p=0.2) at twelve months. Those in the balloon kyphoplasty group also had greater improvement in quality of life by the EuroQol questionnaire at one (0.18 points; 95% CI, 0.08 to 0.28; p=0.0003) and twelve months (0.12 points; 95% CI, 0.01 to 0.22; p=0.025) and improved disability by the Roland-Morris scale at one month (4.0 points; 95% CI, 2.6 to 5.5; p< 0.0001) and twelve months (2.6 points; 95% CI, 1.0 to 4.1; p=0.0012). Balloon kyphoplasty patients had less back pain on a 0 to 10-point numeric rating scale at seven days (2.2 points; 95% CI, 1.6 to 2.8; p< 0.0001) and twelve months (0.9 points; 95% CI, 0.3 to 1.5; p=0.0034) and reported fewer days of limited activity at one month (2.9 days per 2 weeks; 95% CI, 1.3 to 4.6; p=0.0004) and twelve months (1.6; 95% CI, − 0.1 to 3.3; p=0.068). Fewer patients assigned to balloon kyphoplasty took pain medications or used walking aids during follow-up. There was no significant difference in the number of patients with adverse events or serious adverse events in the kyphoplasty and nonsurgical groups. New radiographically detected vertebral fractures occurred in 41.8% of subjects in the balloon kyphoplasty and 37.8% in the nonsurgical group (4% difference; 95% CI − 7.5 to 15.6; p=0.5) and were not statistically different.

Conclusion: Compared to nonsurgical treatment, balloon kyphoplasty safely improved quality of life and reduced back pain, disability and the use of pain medications and walking aids. Significant improvements in multiple measurements of quality of life, pain and disability continue for at least 1 year. Balloon kyphoplasty did not increase adverse events including the risk of vertebral fractures (Clinicaltrials.gov number, NCT00211211).

Aim: To measure the effect of X-stop interspinous decompression device on the dural sac and foraminal area at 6 and 24 months post operatively at the instrumented level in patients with symptomatic lumbar canal stenosis.

Design: Prospective Observational Study of 48 patients.

Methods: Patients due to have an X stop procedure were included and had a positional MRI scan preoperatively and 6 & 24 months post operatively. Foraminal area was measured in flexion and extension position whereas dural cross sectional area was measured in erect, neutral, flexion and extension positions. Osiris 4.17 software program was used to measure the canal and foraminal dimensions. The data was analysed using paired t test on SPSS ver.15.01.

Results: Forty-eight patients (25 male and 23 female) underwent scans preoperatively and at six months. Twenty-nine patients had single level and 19 had double level procedures. Three patients had removal of X stop and 5 did not have scan at 24 months leaving 40 patients scanned at 24 months. Of these 38 scans were complete and were included. We noted increase in mean dural sac area in all positions. The mean dural sac area increased from 131 mm2 to 143 mm2 (p=0.144) at 6 months and from 137 mm2 to 202 mm2 (p= 000) at 24 months in standing position. The difference in pre-operative measurements in the six and 24-month measurements is because of the different patient numbers scanned. There were similar increased dural sac areas in the other positions. The mean foraminal areas were measured in flexion and extension and the measurements in extension were increased from 66.58 mm2 to 79.51 mm2 (p=. 001) at 6 months and from 68.10 to 69.57 mm2 (p=0.752) at 24 months on left side; and increased from 63.75 mm2 to 71.65 mm2 (p=0.036) at 6 months, from 65.54 mm2 to 68.01mm2 (p=0.440) at 24 months on right side. Thus there is a small increase in foraminal areas and statistically significant increase in dural sac areas at 24 months.

Conclusion: X-stop interspinous device remains effective in decompressing the stenosed spinal segment by increasing the anatomic dural cross sectional areas and foraminal areas of spinal canal at 24 months post operatively, thus providing symptomatic relief from lumbar canal stenosis.

Aim: To study the effect of X-stop interspinous decompression device on the lumbar spine kinematics at 6 and 24 months post operatively at the instrumented and adjacent levels in patients with symptomatic lumbar canal stenosis.

Design: Prospective Observational Study of 48 patients.

Methods: Patients due to have an X stop procedure were included and had a positional MRI scan preoperatively, 6 and 24 months post operatively in erect, flexion, extension and neutral position. Disc heights, endplate angles, segmental and lumbar spine motion was measured at stenosed instrumented and adjacent levels. Osiris 4.17 software program was used to measure the canal and foraminal dimensions. The data was analysed using paired t test on SPSS ver.15.01.

Results: Forty-eight patients (25 Male and 23 Female) underwent scans preoperatively and at 6 months. Twenty-nine patients had single level and 19 had double level procedures. Three patients had removal of X stop and 5 did not have scan at 24 months, leaving 40 patients scanned at 24 months. Of these, 38 scans were complete and were included. Mean anterior disc height reduced from 7.1 mm to 6.3 mm (p=0.004) from 48 scans at 6 months and from 7.2 mm (pre-operative) to 5.9 mm (at 24 months) – (p=0.000) from 38 scans at 24 months at the instrumented level. We hypothesise that the reduction in anterior disc heights could be a result of the interspinous distraction plus the natural progression of spinal stenosis and ageing. There was no significant change in posterior disc heights at instrumented level or adjacent levels. The mean lumbar spine motion was 22.89o, 21.3 o and 21o (p=0.183) preoperatively, 6 and 24 months respectively. The total range of movements of lumbar spine and individual segments were measured. There was no significant change in the segmental range of motion at instrumented and adjacent levels.

Conclusion: X-stop interspinous device does not significantly alter the kinematics of lumbar spine at instrumented and adjacent levels at 6 and 24 months postoperatively.

Aim: To assess the clinical effectiveness of X stop interspinous decompression device in patients with neurogenic claudication due to lumbar canal stenosis at 24 months post surgery.

Design: Prospective Observational Study of 57 patients with X stop procedure.

Methods: Fifty-seven patients with unilateral or bilateral leg pain due to lumbar canal stenosis, who had significant relief from sitting or flexing the lumbar spine, were treated with X stop.

Clinical outcome was assessed by Zurich claudication questionnaire (ZCQ), visual analogue score (VAS), Oswestery disability index (ODI) and SF36 questionnaires preoperatively and at 2 years. ZCQ has three components- symptom severity, physical function and patient satisfaction. ZCQ is considered the most precise, reliable and condition specific questionnaire for lumbar canal stenosis.

Out of 57 patients, 2 died due to unrelated causes, 3 withdrew from study and 3 had the device removed within 2 years. Forty-five, 44, 42 and 48 completed ZCQ, ODI, SF-36 and VAS respectively at 24 months.

Results: The mean age was 71(53–94) and M: F ratio 29:28. X stop device was inserted at single level in 32 (56%) and double levels in 25(44%) patients. In single level cases, 72% reported improvement in symptom severity, 65% in physical function, 68% were satisfied with the procedure, and overall 55% made a clinically significant improvement at 24 months. In double level cases, the figures were 62%, 68%, 78% and 40% respectively. The threshold for changes in symptom severity was 0.46, physical function was 0.42 and patient satisfaction 2.42. Overall clinically significant improvement requires that a patient achieves at least 2 criteria.

The mean ODI improved by 6.5 in single level and 10.8 in double level cases. The SF-36 showed improvement in physical function, role physical, bodily pain and vitality social domain.

Average hospital stay for the procedure was 1.6 days. One patient stayed for 10 days for investigation unrelated to the procedure. There were no major complications.

Conclusions: The results of our study show that the X stop interspinous decompression device remains clinically effective at the end of 2 years. X stop is a relatively less invasive procedure, especially suitable for patients with other co-morbidities, which can be performed as a day case procedure without major complications.

Purpose of the Study: To ascertain the role of Dynesys system (Zimmer Spine, Minneapolis) in the surgical management of chronic low back pain

Methods: 55 patients with persistent low back pain despite conservative measures were treated with Dynesys over a period of two and a half years. Participants either underwent Dynesys procedure alone or in combination with fusion or decompression surgery. Oswestry Disability Index (ODI), Visual Analogue Scores (VAS) and SF-36 questionnaires were completed pre-operatively and at one and two years post-operatively. Pre-operative testing using the Distress and Risk Assessment Method (DRAM) identified psychological distress prior to surgery. Patient Oriented Outcome questionnaires were circulated retrospectively following surgery to obtain data regarding patient’s perceptions and expectations of their outcome.

Results: Overall, the mean ODI reduced by 10.23% after one year and 16.15% after two years following surgery. VAS improved by 12mm one year and by 17mm two years after operation. Patients with psychological distress pre-operatively showed less improvement in their ODI and VAS at two-year follow up. The results of fusion were similar to Dynesys alone, and patients who also had decompression had best results. 72.2% patients reported an improvement following their surgery and the same percentage would have the operation again in retrospect.

Conclusion: This is the first study exploring clinical outcomes following surgery using Dynesys dynamic stabilization system in patients with disabling low back pain. Previous studies have reported good outcome in the treatment of spinal stenosis. Over 70% patients in our study reported improvement following the procedure but more evidence is needed to determine if it is a viable alternative to spinal fusion.

Aim: To assess the kinematic changes that occur within the lumbar spine 2 years following insertion of the Dynesys Spinal stabilisation implant.

Materials and Methods: Twenty patients who were treated with Dynesys surgical stabilisation for dominant lower back pain underwent positional MRI scanning before and two years following surgery.

The patients were divided into two groups, A and B. The first, Group A, in which only Dynesys was used and the second, Group B, in which Dynesys was used adjacent to one or more fused segments.

Results: The results of the pMRI measurements showed that the range of movement (ROM) of the L1/S1 angle in Group A reduced by 11.8o{pre-op=37.9o, postop=26.1o(p=0.085)} while in Group-B reduced by 12.3o {pre-op=37.8o, postop=25.5o(p=0.017)}.

The ROM of the end plate angle at the instrumented segments in Group A reduced from 5.72^o to 1.44^o{difference 4.28^o(p=0.005)} and in Group B reduced from 6.00^o to 2.17^o,{difference 3.83^o(p=0.001)}.

The ROM of the end plate angle at the level above instrumentation in Group A reduced from 8.2^o to 5.1^o {reduction 3.1^o(p=0.085)}, while in group-B increased from 7.3^o to 7.5^o, a difference of 0.2^o (p=0.877).

The mean anterior disc height in Group A reduced by 2.1mm (p< 0.001) from 9.59mm to 7.44mm. The posterior disc height also reduced from 6.56mm to 6.26mm, a difference of 0.3mm, (p=0.434). In Group B, the anterior disc height reduced by 1.98mm (pre-op=9.04mm, post-op= 7.06mm, p=0.001) and the posterior height by 0.35mm (pre-op 6.14mm to post op 5.79mm, p=0.443)

Discussion: This study shows that the Dynesys stabilisation system allows some movement at the operated segment two years following surgery. The study also confirms that the adjacent segment hypermobility often seen following spinal fusion surgery is eliminated.

Purpose of the Study: To assess the use of synthetic hydroxyapatite for postero-lateral spinal fusion using a new classification system

Methods: This is a prospective study on 30 patients who underwent bilateral postero-lateral spinal fusion between October 2002 and January 2004. The sides were randomised to synthetic phase pure Hydroxyapatite (Apapore® 70) mixed with bone marrow and autologus bone on one side and Apapore® 70 with bone marrow on the other. Plain Antero-posterior and Lateral x-rays were done in the immediate post-operative period and at 3, 6, 12 and 24 months. Two independent observers assessed the Antero-posterior films using a new classification system. Spine was considered fused when either or both sides showed good evidence of bone formation between the graft particles and graft and transverse process.

Results: In 6 patients x-rays were lost and 2 did not have two year follow-up. Twenty of the remaining 22 patients (90.9%) showed evidence of fusion as documented by both the observers. Good evidence of bone formation was noted as early as 6 months on the side where Apapore was used with bone marrow with 90.9 % achieving fusion at 2 years as against 57.1 % on the opposite side. The inter-observer agreement was good (mean 81.6%) with kappa score of 0.736.

Conclusion: The Hydroxyapatite based bone graft substitutes behave differently than autologus bone graft and poses difficulty in assessing fusion according to the radiographic classification systems described. The classification described above is useful in such situations and has shown to have good inter-observer reliability. With the increasing use of bone substitutes this classification system may be valuable in assessment of fusion and inter-study correlation.