Introduction Minimally invasive lumbar discectomy using the METRx™ System (MAST discectomy) has been advocated as an alternative to open microdiscectomy for symptomatic posterolateral lumbar disc herniation. This paper presents a quality assurance dual surgeon retrospective study with independent observer minimum twelve month follow-up.

Methods This study was approved by the Ethics Committee of the Princess Alexandra Hospital prior to commencement. All patients who underwent MAST discectomy using the METRx™ System for the management of radiculopathy caused by posterolateral lumbar disc herniation under the care of two surgeons (AN and RK) more than twelve months prior to the commencement of assessment were included in the study. The patient demographic data was collected contemporaneously, operation performance data was collected retrospectively from hospital databases and outcome data was collected by telephone interview by independent observers (PL, SO and JP) a minimum of twelve months after discharge from hospital.

Results 101 patients (53 males, 48 females) (average age 43 years, range 17 to 83 years) underwent 102 procedures between July 2001 and December 2004. Surgery was performed on the right side in 63 cases and was either at L4/5 (30%) or more commonly L5/S1 (70%). 21 were public patients and 80 private patients with 59 episodes of surgery occurring in a public hospital. 46 operations were performed with the METRx™ MED System and 56 with the METRx™ MD System. The average duration of surgery for patients at the Princess Alexandra Hospital (n = 48) was 88 minutes with an average length of post-operative hospital stay of 22 hrs 35 mins. 16 of these cases were performed as day surgery. Perioperative complications were: conversion to open (3), urine retention (7), nausea and vomiting (3), durotomy (5), wound haematoma not requiring surgery (1) and incorrect level surgery identified and rectified during surgery (1). The average length of time from surgery to independent follow-up was 679 days (range: 382 to 1055) with 78% successful contact. On the Modified McNabb Outcome Scale, 83% reported an excellent or good outcome, 9% reported a fair outcome and 8% a poor outcome. The time until return to work was identified as less than two weeks in 28% and between 2 weeks and 3 months in 39%. Patients whose surgery was funded by Workers Compensation were over-represented in both the poor outcomes and delayed return to work. 4 patients reported progressive severe low back pain, 10 patients reported ongoing lower limb pain (severe in 1 and mild in 9) and 1 patient underwent surgery for a recurrent disc prolapse. Further disc prolapse at different sites was identified in five patients.

Discussion The retrospective data in this study forms class IV evidence for efficacy. As a quality assurance exercise it suggests an acceptable level of safety and efficacy to allow further technique development and study. A prospective randomized controlled study is proposed. The high incidence of urine retention early in the series of one surgeon is considered to be related to the practice of placing depot morphine in the operative bed. The reduction in complications in general and the improvement in duration of surgery over the series is evidence of the learning curve for this procedure.

Introduction A prospective, randomised, controlled study has been conducted to compare the clinical outcomes of patients treated with a Presige® artificial cervical disc (Medtronic Sofamor Danek, Memphis, TN) to patients who receive fusion after cervical discectomy for the treatment of primary cervical disc disease. It is hypothesized that maintenance of motion after anterior cervical discectomy will prevent the high rate of adjacent level premature degeneration. The primary purposes of the study are to (1) prove equivalence (non inferiority) of outcome of the disc prosthesis in the short term compared with fusion; and (2) to asses the ability of the prosthesis to maintain motion. Enrolment has closed and this is a report of the data with 50 cases with 6 month follow-up and 9 cases having reached 24 month final follow-up.

Methods In four centres, 52 patients with primary, single level cervical disc disease producing radiculopathy and/or myelopathy were randomised prospectively to receive anterior cervical discectomy with either fusion or artificial cervical disc replacement. The patients were evaluated with pre and postoperative serial flexion-extension cervical x-rays at 6 weeks, 3, 6, 12, and 24 months. At the same intervals, the patients had pre and postoperative neck disability indexes, visual pain analogue scales, European myelopathy scores, SF-36 general health scores, and neurological status examinations assessing the patient’s reflex, motor and sensory function.

Results At 6 weeks the neck disability index reduced by 34.1 for the investigational group compared to 35.2 for the fusion group. The improvement seen in the treatment groups was statistically equivalent (p < 0.05, non-inferiority margin = 10) up to the 24-month follow-up interval. The pain score had reduced by 7.7 for the investigational group and by 9.7 for the control group. Both groups improved statistically from preoperatively though statistical equivalence could not be shown. This improvement appeared to be maintained until the 12 month follow-up. Mean arm pain scores improved in both groups with statistical equivalence being demonstrated (p < 0.05, non-inferiority margin = 10). The adverse events in both groups were similar. Analysis of range motion showed a mean preoperative range of motion in the arthroplasty group of 5.9 degrees and 6.3 degrees in the fusion group. At twelve months the arthroplasty group had a mean range of motion of 5.9 degrees and the fusion group had a mean range of motion of 1.1 degrees

Discussion Anterior cervical discectomy and fusion has a good short term outcome though there is a high incidence of failure at adjacent levels over time. It is hypothesised that the maintenance of motion of a segment will prevent adjacent premature degeneration. It will take long term follow-up studies however to prove this. In the mean time, the justification to insert artificial cervical prostheses rests on being able to prove equivalence of outcome between fusion and prosthesis in the short term. This paper shows that, in the short to medium term, the clinical outcomes appear to be equivalent to fusion. And that range of motion is maintained.

Introduction: A prospective, randomized, controlled study has been conducted to compare the clinical outcomes of patients treated with an artificial cervical disc to patients who receive fusion after cervical discectomy for the treatment of primary cervical disc disease. It is hypothesized that maintenance of motion after anterior cervical discectomy will prevent the high rate of adjacent level premature degeneration. The primary purpose of the study is to prove equivalence (non inferiority) of outcome of the disc prosthesis in the short term compared with fusion. Enrolment has closed and this is a report of the data with 50 cases with 6 month follow-up and 9 cases having reached 24 month final follow-up.

Methods: In four centres, 52 patients with primary, single level cervical disc disease producing radiculopathy and/or myelopathy were randomised prospectively to receive anterior cervical discectomy with either fusion or artificial cervical disc replacement. The patients were evaluated with pre- and post-operative serial flexion-extension cervical x-rays at 6 weeks, 3, 6, 12, and 24 months. At the same intervals, the patients had pre and postoperative neck disability indexes, visual pain analogue scales, European myelopathy scores, SF-36 general health scores, and neurological status examinations assessing the patient’s reflex, motor and sensory function.

Results: At 6 weeks the neck disability index reduced by 34.1 for the investigational group compared to 35.2 for the fusion group. The pain score had reduced by 7.7 for the investigational group and by 9.7 for the control group. This improvement appeared to be maintained until the 12 month follow-up. The mean pain scores at 24 months were similar (4.3 and 5.6 respectively) In general there appeared to be a slightly better outcome for the investigational group, though the investigational group showed slightly less preoperative pain (p=0.091) and disability (p=0.055) than the fusion group. Both pain score and disability scores improved statistically significantly compared to the pre op scores (p< 0.001 all comparisons). Analysis of non-inferiority of outcome for the investigational group using ANCOVA with the preoperative score as the covariate and a non-inferiority margin of 5 points (5%) showed statistical significance at 12 weeks for Neck Disability Index.

Discussion: Anterior cervical discectomy and fusion has a good short-term outcome though there is a high incidence of failure at adjacent levels over time. It is hypothesized that the maintenance of motion of a segment will prevent adjacent premature degeneration. It will take long term follow-up studies however to prove this. In the mean time, the justification to insert artificial cervical prostheses rests on being able to prove equivalence of outcome between fusion and prosthesis in the short term. This paper shows that the outcomes appear to be equivalent. Though there is insufficient power to prove equivalence with a clinical margin of 5%.

Introduction: Patients with malignant spinal disease who have neurologic symptoms are often considered poor surgical candidates. The aim of this paper is to review the effect on neurologic symptoms of surgical management of malignant spinal disease.

Methods: A retrospective review of patients treated from January 1993 to June 2003 was undertaken. Pain status was assessed using patient statements and recorded analgesic requirements. Neurologic symptoms were assessed using Frankel’s grading.

Results: There were 95 patients (32 females aged 26–83; 63 males aged 15–89). No patients were asymptomatic. 61 of 109 presentations were with multiple symptoms. The most common symptom was pain (99) – either localised (8), non-specific back (56) and/or radicular (57). The next most frequent symptom was weakness (54). The time course of onset varied from acute ward deterioration, with urgent surgery, to slow progression over weeks, prior to elective surgery. 8 cases had sphincteric dysfunction.

There were 98 tumours treated. In females, the most common tumours were breast (8) and renal (4) and in males, prostate (13), multiple myeloma (12) and lung (10). The thoracic spine was involved in 62, the lumbar in 18, cervical in 16 and sacral in 2. The vertebral body was involved in 76.

There were 109 operations. An instrumented fusion was performed in 82. Surgical approach was anterior in 17 (9 cervical, 8 thoracic) and posterior in 80 (5 cervical, 56 thoracic and 17 lumbar). Six patients had combined approaches (2 cervical, 3 thoracic and 1 lumbar). Two patients were treated for metachronous tumours. One patient had non-contiguous metastases treated separately. One patient was treated for local recurrence. One patient had revision for implant failure (anterior thoracic). One patient was explored after deterioration due to loss of autoregulation. Thoraco-abdominal approaches (12) were associated with ileus (2) and pneumonia (3). Of four cases with deep wound infections, three had received prior local irradiation. Two patients died of pulmonary embolus. 83 patients survived beyond three months.

All patients demonstrated improvement in pain status. Thirteen of 29 non-ambulatory cases were able to mobilise postoperatively. There were 32 whose Frankel grades improved. Seventeen of these returned to normal (15 from Grade 4 and 2 from Grade 3). One patient with complete motor and sensory loss improved to useful but subnormal status, three others improved to residual motor function. 11 other patients improved one grade. Of those whose scores did not change (76), 53 remained normal, eight maintained useful but subnormal status, five were stabilised with residual motor function, three kept some sensory perception and two had complete motor and sensory loss. One patient deteriorated from residual motor function to complete motor loss. The outcome for sphincter dysfunction (8) was not clear from the notes. In no case was a specific change in function documented.

Discussion: Surgical treatment of malignant spinal tumours is worthwhile. Posterior approaches are versatile and should be considered. Surgery is effective in the management of pain and preserves or may significantly improve neurologic function.

Introduction: A prospective, randomized, controlled study has been conducted to compare the clinical outcomes of patients treated with an Artificial Cervical Disc to patients who receive fusion after cervical discectomy for the treatment of primary cervical disc disease. It is hypothesized that maintenance of motion after anterior cervical discectomy will prevent the high rate of adjacent level premature degeneration. The primary purpose of the study is to prove equivalence (non inferiority) of outcome of the disc prosthesis in the short term compared with fusion.

Methods: In four centers, 60 patients with primary, single level cervical disc disease producing radiculopathy and/or myelopathy are randomized prospectively to receive anterior cervical discectomy with either fusion or artificial cervical disc placement. The patients are evaluated with pre and postoperative serial flexion-extension cervical x-rays at 6 weeks, 3, 6, 12, and 24 months. At the same intervals, the patients have pre and postoperative neck disability indexes, visual pain analogue scales, European myelopathy scores, SF-36 general health scores, and neurological status examinations assessing the patient’s reflex, motor and sensory function.

Results: Data is presented for the first 47 patients. At 6 weeks the neck disability index reduced by 36.1 for the investigational group compared to 34.8 for the fusion group. The pain score had reduced by 8.2 for the investigational group and by 9.9 for the control group. This improvement appeared to be maintained until the 12 month followup. In general there appeared to be a slightly better outcome for the investigational group. Both pain score and disability scores improved statistically significantly compared to the pre op scores (p< 0.001 all comparisons). Analysis of non inferiority of outcome for the investigational group using ANCOVA with the preoperative score as the covariate and a non inferiority margin of 5 points showed statistical significance at 6 and 12 weeks for Neck disability index. Operative time appeared slightly less (2.3 hrs) for the investigational group compared to the fusion group(2.5hrs). Blood loss also appeared higher in the fusion group (165 mls compared to 91 mls). Hospital stay was equivalent (2.8 days and 2.9 days).

Discussion: Anterior cervical discectomy and fusion has a good short term outcome though there is a high incidence of failure at adjacent levels over time. It is hypothesized that the maintenance of motion of a segment will prevent adjacent premature degeneration. It will take long term followup studies however to prove this. In the mean time, the justification to insert artificial cervical prostheses rests on being able to prove equivalence of outcome between fusion and prosthesis in the short term. This paper shows that the outcomes appear to be equivalent. Early statistical evidence is available for some of the outcome measures at early post op followup. Further statistical power will be available when the full 60 cases are available for study and this may give further weight to the hypothesis of equivalence of outcome.

INTRODUCTION: A prospective, randomised, controlled study has been conducted to compare the clinical outcomes of patients treated with an Artificial Cervical Disc to patients who receive fusion after cervical discectomy for the treatment of primary cervical disc disease. It is hypothesised that maintenance of motion after anterior cervical discectomy will prevent the high rate of adjacent level premature degeneration. The primary purpose of the study is to prove equivalence (non inferiority) of outcome of the disc prosthesis in the short term compared with fusion.

METHODS: In four centres, 60 patients with primary, single level cervical disc disease producing radiculopathy and/or myelopathy are randomised prospectively to receive anterior cervical discectomy with either fusion or artificial cervical disc placement. The patients are evaluated with pre- and post-operative serial flexion-extension cervical X-rays at six weeks, three, six, 12, and 24 months. At the same intervals, the patients have pre- and post-operative neck disability indexes, visual pain analogue scales, European myelopathy scores, SF-36 general health scores, and neurological status examinations assessing the patient’s reflex, motor and sensory function.

RESULTS: Data are presented for the first 47 patients. At six weeks the neck disability index reduced by 36.1 for the investigational group compared to 34.8 for the fusion group. The pain score had reduced by 8.2 for the investigational group and by 9.9 for the control group. This improvement appeared to be maintained until the 12 month follow-up. In general there appeared to be a slightly better outcome for the investigational group. Both pain score and disability scores improved statistically significantly compared to the pre-operative scores (p< 0.001 all comparisons). Analysis of non inferiority of outcome for the investigational group using ANCOVA with the pre-operative score as the covariate and a non inferiority margin of five points showed statistical significance at six and 12 weeks for Neck disability index. Operative time appeared slightly less (2.3 hours) for the investigational group compared to the fusion group (2.5 hours). Blood loss also appeared higher in the fusion group (165 mls compared to 91 mls). Hospital stay was equivalent (2.8 days and 2.9 days).

DISCUSSION: Anterior cervical discectomy and fusion has a good short term outcome though there is a high incidence of failure at adjacent levels over time. It is hypothesised that the maintenance of motion of a segment will prevent adjacent premature degeneration. It will take long term follow-up studies however to prove this. In the meantime, the justification to insert artificial cervical prostheses rests on being able to prove equivalence of outcome between fusion and prosthesis in the short term. This paper shows that the outcomes appear to be equivalent. Early statistical evidence is available for some of the outcome measures at early post-operative follow-up. Further statistical power will be available when the full 60 cases are available for study and this may give further weight to the hypothesis of equivalence of outcome.