The February 2024 Spine Roundup. 360. looks at: Surgeon assessment of bone – any good?; Robotics reduces radiation exposure in some spinal surgery; Interbody fusion cage versus anterior lumbar interbody fusion with posterior instrumentation; Is robotic-assisted pedicle screw placement an answer to the learning curve?; Acute non-traumatic spinal subarachnoid haematomas: a report of five cases and a systematic review of the literature; Is L4-L5 lateral interbody fusion safe and effective?

Purpose: We analysed the radiographic course of anterior lumbar interbody fusion achieved via a minimal anterior extraperitoneal approach. Material and methods: From January 1996 to December 2001, we operated 198 patients with this technique. Twenty-one patients were excluded from the analysis (two deaths, three tumours, 16 follow-ups less than 12 months). Mean age of the 177 patients retained for study was 53 years (range 22–78). Mean follow-up was 2.7 years. The 55 post-trauma cases involved essentially thoracolumbar junction. The 122 cases of degenerative lumbar spine included 14 cases of scoliosis, 26 cases of spondylolisthesis, 72 cases of unstable spines after primary posterior surgery, and 10 isolated degenerative discs. Only eight patients did not have posterior fixation. Fusion (globally 360 levels) concerned one disc in 89 patients, two discs in 71, three discs in 17. Cancellous autologous grafts were used with cages. Tricortical grafts were implanted after corporectomy (n=23). Radiological fusion was confirmed by the absence of a mobility chamber around the pedicular screws, the cages or the tricortical grafts, and by searching for loss of sagittal angles (digitalized scans and x-ray, Auto Cad L.T.2000). Results: 1) Early postoperative status. For the post-trauma cases (65 fused levels, 55 patients), a simple callus was observed in 28. For the others, mean correction was 4° per level. 2) Angle loss. For the trauma cases, mean angle loss was 3.9° in 36 cases (29 grafts on a single level). There were two partial expulsions of the tricortical grafts implanted in osteoporotic patients; revision was not attempted. Mean angle loss for the 65 grafted levels was 2°. For the degenerative cases, mean angle loss was 3.7° for 172 fused levels (112 patients). Cage expulsion on a grade 3 spondylolisthesis did not warrant revision. Two cage impactions did not cause significant loss of angle. 3) Anatomic status of the grafts. Fusion was achieved at all levels without cage or tri-cortical graft rupture. We observed a partial but stable lucent line around the case in five cases. Discussion: The rate of fusion reported after anterior lumbar interbody fusion has varied from 55 to 100% in the literature. This technique is an original approach for trauma victims avoiding the need for extensive posterior assemblies and/or the damage caused by a wide anterior approach. For the degenerative spine, the mediocre quality of the bone and the frequency of several level fusions is not a particular problem. Conclusion: Anterior lumbar interbody fusion is an interesting method for reinforcing posterior fixation with a real efficacy in terms of effective fusion

Introduction. Reported incidence of DVT after spinal surgery ranges from 0-15% and PE 0.5-2.7%. Theoretically, manipulation of the vessels and venous stasis caused by retraction during anterior lumbar inter-body fusion may increase the propensity for thrombosis. The reported incidence of DVT and PE following major abdominal and pelvic surgery are high (up to 23%) and all these patients routinely receive chemical prophylaxis. Aim. Should patients undergoing ALIF surgery receive chemical prophylaxis routinely?. Materials and Methods. Retrospective review of ALIF procedures done between Jan 2007- Jan 2010. Review of case notes, radiology reports and telephone call to the patients to exclude DVT. Total of 76 patients underwent ALIF during this period. Forty six were female(60.5%) and 36 were 2 level fusions(47%). L5-S1 being commonly fused (76%) followed by L4-L5 (23%). Average surgical time from theatre records is 115 minutes(31-369 minutes). All patients received mechanical prophylaxis in the form of thigh length TED stockings. None of the patients were on treatment for DVT prior to surgery. Results. Three patients (3.9%) had Doppler proved DVT which required anticoagulation treatment. There was no reported incidence of PE. Discussion. There is no definite evidence in the literature to suggest ALIF surgery has higher incidence of thromboembolic complications, though theoretical possibility of increased risk. Current study suggests that incidence is 3.9% with mechanical prophylaxis alone which is very small when compared to incidence after major abdominal, pelvic or gynaecological procedures. Our small study sample suggests routine use of chemical prophylaxis to reduce the risk of DVT for anterior lumbar inter-body fusion is not justified

Objectives: To assess the outcome of patients undergoing anterior lumbar interbody fusion with the Hartshill Horseshoe cage device. Study Design: Prospective cohort of patients from a single centre in the UK. Methods: 20 patients underwent anterior lumbar inter-body fusion from September 1994 to November 2002. All patients underwent primary anterior fusion alone. The diagnosis was back pain alone in 10 patients, instability and back pain post discectomy in 9 patients and pseudoarthrosis in the remaining patient. The main outcome measures were oswestry disability index, low back outcome score, visual analogue scale for back and leg pain, modified somatic perception and modified zung depression score. Results: Follow-up data was available for 17 patients at two years (85%). There were 11 females and 9 males and there average age at operation was 39 years (range 30–50 years). The mean ODI pre-op was 56 and this improved to 30 post-op (p=0.004). The mean LBOS pre-op was 21 and this improved to 41 post-op (p=0.005). The VAS pre-op was 83mm and improved to 48mm postop (p=0.01). Overall 13 of the patients (76%) improved their ODI by a minimum of 10 points. When comparing the groups according to diagnosis, the patients with back pain alone had a 17 point improvement in ODI whereas the patients with back pain post discectomy had a 29 point improvement in ODI (p=0.33). The main complication of surgery was common iliac vein tear occurring in two patients which was repaired intra-operatively. Conclusion: Anterior lumbar interbody fusion using the Hartshill horseshoe cage device is a safe and effective method of achieving spine stabilisation in patients with back pain. It seems to be particularly effective for those patients who have instability and back pain post-discectomy

Objective: This is a prospective study by an independent observer in which outcomes of 118 anterior lumbar interbody fusions (ALIF), done for discogram-concordant axial low back pain, were evaluated. Aims of the study were to assess overall functional and comprehensive outcomes, predictors of outcome, and whether ALIF alone can be recommended for low back pain. Design: The functional and patient perception assessment was based on a self-evaluation back pain questionnaire, which consisted of Oswestry Disability Index, Pain Chart, Numerical Rating Scales (NRS) for back pain and leg pain and SF-36-Version II. The comprehensive outcomes were categorised as satisfactory (excellent, good or improved) and unsatisfactory (fair, poor, unimproved or worse). Results: Overall, we had 61% satisfactory outcomes. Average percentage change in ODI, NRS and SF-36 PCS scores was statistically quite significant. However, patients who had previous posterolateral fusion at the same level had satisfactory outcome in 81%. Incidence of non-union was higher in two-level fusions than one-level fusions, and cases that developed non-unions had unsatisfactory outcome. Conclusions: ALIF alone can be recommended for discogram-concordant axial low back pain. Radiographic evidence of spondylosis, lysis or listhesis, level of fusion, number of levels fused, floating/non-floating type of fusion, and previous back surgery did not affect the outcome. Cases in which the middle column was stabilised (such as those with (a) intervertebral cages extending up to the posterior longitudinal ligament and (b) previous posterolateral fusion at the same level), and hence biomechanically stable, showed better outcomes. Placement of intervertebral implants mainly in the anterior column lead to distraction of the disc anteriorly, resulting in compression of back wall of the disc and facet joints, and narrowing of intervertebral foramina and spinal canal at that level, thus compromising the outcome

Introduction Numerous in-vitro studies demonstrating increased stress at levels adjacent to a lumbar fusion have raised concerns of accelerated degeneration. However, the significance of this increased stress in the in-vivo setting remains unclear, especially with long-term follow-up. The objective of this study was to assess the level of degeneration on MRI in this same cohort of patients at a minimum of 20 years follow-up. Methods Thirty-seven patients undergoing lower lumbar anterior lumbar interbody fusion with a minimum of 20 years follow-up were identified. Only patients with normal pre-operative discograms at the level adjacent to the fusion were considered in this study. MRI scans were performed and evaluated for any evidence of degeneration by an independent radiologist. Advanced degeneration was defined as either: (1) absence of T2 signal intensity in the disk, (2) disk herniation, or (3) spinal canal stenosis. Results Advanced degeneration was identified in eight (22%) patients, with five (14%) being isolated to the adjacent level. Nineteen (51%) other patients had evidence of early degeneration in their lumbar spine. Overall, 10 (26%) patients had some evidence of degeneration isolated to the level adjacent to the disk whereas 17 (31%) patients had multilevel degeneration and six patients (16%) had degeneration in their lumbar spine but preservation of the adjacent level. There was no relationship between function and radiographic degeneration. Conclusions Without a control group, it is difficult to make firm conclusions on whether the changes seen on MRI represent the natural history of spinal deterioration or represent accelerated degeneration. However, after 20 years, only a handful of patients developed advanced adjacent level degeneration. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors inherent within the individual as opposed to the increased biomechanical stresses at the adjacent levels

Introduction: Numerous in-vitro studies demonstrating increased stress at levels adjacent to a lumbar fusion have raised concerns of accelerated degeneration. However, the significance of this increased stress in the in-vivo setting remains unclear, especially with long-term follow-up. The objective of this study is to assess the level of degeneration on MRI in this same cohort of patients at a minimum of twenty years follow-up. Methods: Twenty-five patients undergoing one or two level anterior lumbar interbody fusion at the L5-S1 or L4–5 levels with a minimum of twenty-years follow-up were identified. Only patients with normal preoperative discograms at the level adjacent to the fusion were considered in this study. MRI scans were performed and evaluated for any evidence of degeneration by an independent radiologist. Advanced degeneration was defined as either: (1) absence of T2 signal intensity in the disk, (2) disk herniation, or (3) spinal canal stenosis. Results: Advanced degeneration was identified in five (20%) patients, with three (12%) being isolated to the adjacent level. Fourteen (56%) other patients had evidence of early degeneration in their lumbar spine. Overall, eight (32%) patients had some evidence of degeneration isolated to the level adjacent to the disk whereas seven (28%) patients had multilevel degeneration and four patients (16%) had degeneration in their lumbar spine but preservation of the adjacent level. Discussion & Conclusion: Without a control group, it is difficult to make firm conclusions on whether the changes seen on MRI represent the natural history of spinal deterioration or represent accelerated degeneration. However, after twenty-years, only a handful of patients developed advanced adjacent level degeneration. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors inherent within the individual as opposed to the increased biomechanical stresses at the adjacent levels

INTRODUCTION: Numerous in-vitro studies demonstrating increased stress at levels adjacent to a lumbar fusion have raised concerns of accelerated degeneration. However, the significance of this increased stress in the in-vivo setting remains unclear, especially with long-term follow-up. The objective of this study is to assess the level of degeneration on MRI in this same cohort of patients at a minimum of twenty years follow-up. METHODS: Twenty-five patients undergoing one or two level anterior lumbar interbody fusion at the L5-S1 or L4-5 levels with a minimum of twenty-years follow-up were identified. Only patients with normal pre-operative discograms at the level adjacent to the fusion were considered in this study. MRI scans were performed and evaluated for any evidence of degeneration by an independent radiologist. Advanced degeneration was defined as either: (1) absence of T2 signal intensity in the disk, (2) disk herniation, or (3) spinal canal stenosis. RESULTS: Advanced degeneration was identified in five (20%) patients, with three (12%) being isolated to the adjacent level. Fourteen (56%) other patients had evidence of early degeneration in their lumbar spine. Overall, eight (32%) patients had some evidence of degeneration isolated to the level adjacent to the disk whereas seven (28%) patients had multilevel degeneration and four patients (16%) had degeneration in their lumbar spine but preservation of the adjacent level. DISCUSSION AND CONCLUSION: Without a control group, it is difficult to make firm conclusions on whether the changes seen on MRI represent the natural history of spinal deterioration or represent accelerated degeneration. However, after twenty years, only a handful of patients developed advanced adjacent level degeneration. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors inherent within the individual as opposed to the increased biomechanical stresses at the adjacent levels

Background and purposes of study The objective of this study is to report the preliminary clinical data from a stand-alone interbody fusion cage (Stabilis™) from two centres. Methods and results This was a retrospective group comparative study. Anterior lumbar interbody fusion was performed using Brantigan (n=6) or Stabilis™ cages (n=19). Clinical assessment was performed using standardised questionnaires. Lumbar flexion/extension views were used to assess union and implant subsidence. There were no significant differences between the groups for ODI, VAZ, MZ and MSPQ pre-operatively. The Stabilis group showed an improvement in ODI (pre: 49.4; post: 39.3; p=0.024), VAS (pre: 76.1; post: 47.8; p< 0.01) and MZ (pre 32.9; post: 20.6; p< 0.01). There was no statistical improvement in the Brantigan cage group. Despite clinical improvement, five patients in the Stabilis group failed to unite and six demonstrated subsidence of the implant. The relationship between non-union and subsidence was statistically significant (p = 0.017). Furthermore, the change in ODI between patients who united and those who did not was both statistically significant (p=0.03) and the difference in mean ODI between the two groups was considerable (21%). Conclusions: Stand-alone cages show promise, involve a shorter operating time and less tissue trauma for the patient. This study has identified a high rate of non-union and implant subsidence. This did not appear to be clinically relevant

Introduction: Anterior lumbar interbody fusion (ALIF) with posterior stabilisation is an established treatment for degenerative disc disease. 1. Some previous reports have advocated a goal of 360 degree fusion, and condemned posterior stabilisation as it does not achieve fusion of the posterior facet joints. 2. Others have claimed that the concept of a ‘locked pseudarthrosis’ gives satisfactory clinical results. 3. There is also a contention that private or self-funding patients achieve better results after spinal fusion compared to those treated under compensation or Dept. Veterans Affairs (DVA) schemes. Methods: Twenty patients who had undergone an ALIF with posterior stabilisation were retrospectively reviewed. All had a follow-up greater than 12 months. 13 patients were private and 7 non-private. The groups were aged and sex matched. Radiological assessment of fusion was made with reconstruction CT scans. Oswestry Disability Index (ODI) scores were recorded preoperatively, 6 months and 12 months post operation. Results: Patients with locked pseudarthrosis showed no significant difference in outcome compared to those with radiological fusion. Both groups showed signifi cant improvement in ODI scores after ALIF (mean preop. = 52 – range 16-74; mean postop. = 18 – range 0-52; p< 0.01). There was a significantly greater improvement (p< 0.02) in ODI scores in private patients (mean reduction = 41 points) compared to worker’s compensation or DVA patients (mean reduction = 22 points). Discussion: The results indicate that ALIF with posterior stabilisation can achieve good clinical results even with a ‘locked pseudarthrosis’. While there is no significant difference between outcomes in different health funding groups shown in the study, carefully patient select for this treatment is the key to success

Introduction: Anterior lumbar interbody fusion has become a frequently utilised procedure. The trend has been towards less invasive techniques including laparascopic and mini-open techniques. This report examines the results of one procedure and suggests appropriate tools to decrease the learning curve. Methods: Twenty-two patients with a mean age of 41 (17–78) underwent mini-open ALIF with threaded cortical bone dowels. The same senior surgeon performed all procedures (RFD). Indication for the procedure was discogenic pain verified by concordant discography after a failure of a minimum of six months non-operative treatment. Patients were followed at standard intervals. Complications as well as the evolution of surgical technique were recorded prospectively for all patients. Results: Twenty-one of 22 patients had the successful implantation of two dowels at each level. Intraoperative fluoroscopy and auditory EMG monitoring was used in all cases. Thirty-two levels were fused from L2–S1 (Average =1.39 levels). Average length of stay was 2.96 days (1–14). Follow-up averaged 24.93 months (2–36). Fusion was achieved in 15/16(93%) of the one level cases but only 3/6 (50%) of the two level cases. Posterior reoperation with posterolateral fusion and pedicle screws was performed in 2/3 of these patients. Use of a dedicated pin-based anterior lumbar retractor enabled a 45% reduction in incision length with a 40% decrease in operative time. Complications included: massive bleeding (1), post-operative dysesthetic leg pain (2), postoperative kyphosis (2), lateral graft displacement (1). Discussion and conclusion: ALIF remains a formidable surgical procedure. Precise identification of the midline and use of fluoroscopy assures good placement of the devices. Preoperative osteopenia should be recognised and treated with posterior stabilisation. Posterior stenosis should be a relative contraindication. We have abandoned multilevel standalone procedures given the poor fusion rate. A pin-based retractor allows a smaller incision with less operative time. Attention to myriad technical details remains paramount

Anterior lumbar interbody fusion (ALIF) is an accepted surgical treatment for disabling discogenic pain. Additional posterior fixation has been advocated. This is a prospective clinic al study evaluating a stand-alone anterior fusion cage with an integrated titanium plate and four divergent locking screws. Patients who had failed conservative management for lumbar discogenic pain were recruited into the study. All underwent diagnostic discography. Surgery was performed through an anterior retro-peritoneal approach. The fusion cage was packed with autogenous bone graft. Outcome measures included: Visual Analogue Scores (VAS), Oswestry Disability Index (ODI) and SF-36 data. Fine-cut CT was performed at one and two years post-operatively. Fusion was defined as continuous bony trabeculae joining the vertebral bodies. Fifty levels were operated on in 39 patients with a mean age of 40.8 years (22–55). The mean operative time was less than 120 minutes, and mean blood loss less than 100 mls. Radiographic fusion at one year was 78% and 100% at two years. Two year mean VAS sc ores for back pain improved from 7.0 to 3.7 (p< 0.01) and for leg pain from 6.1 to 3.1 (p< 0.01). The mean ODI scores decreased from 50.7 to 31.7 (p< 0.01), and SF-36 (PCS) scores increased from 28.4 to 37.5 (p< 0.01). There were no major complications and no patients have required supplementary posterior fixation. This technique is safe and is as effective as 360° fusion in achieving fusion in the management of discogenic back pain over one and two levels. This technique has the advantage of avoiding the morbidity associated with additional posterior fixation

Introduction The unacceptably low fusion rate with stand-alone ALIF cages led to the practice of combining ALIF with posterior instrumentation. Recently ALIF combined with anterior lumbar plate fixation has been promoted to obviate the need for additional posterior surgery. The purpose of this study is to compare the multidirectional flexibility of ALIF combined with posterior instrumentation (either translaminar facet screws or pedicle screws) to that combined with anterior plate fixation.

Methods Ten human lumbar cadaveric motion segments were tested in the following sequence: (i) intact, (ii) stand alone ALIF cages, (iii) ALIF and anterior lumbar plate, (iv) ALIF with translaminar facet screws, (v) ALIF with pedicle screws. In each condition, the specimens were tested under bending moments of 0–8 Nm flexion, 0–6 Nm extension, 0–6 Nm lateral bending and 0–5 Nm axial rotation. 3D motions were measured using an optoelectronic motion monitoring system.

Results The ALIF cages decreased the ROM in the sagittal and frontal planes (p< 0.05). Their effectiveness improved in the sagittal plane with the combination of either anterior plate or posterior fixation (p< 0.05). There was no statistical difference between the ALIF/ Plate and translaminar screws or pedicle screws in flexion-extension and axial rotation ROM. There was a difference in the lateral bending ROM between the ALIF with anterior plate and ALIF with either translaminar facet screws or ALIF with pedicle screws (p< 0.05) favouring posterior fixation. However there was no statistical difference between the combined ROM for ALIF/Plate and translaminar screws or pedicle screws.

Discussion This study shows that the stability achieved with the combination of ALIF with an anterior plate is comparable to that achieved with posterior instrumentation with translaminar facet screws or pedicle screws. This suggests that sufficient segmental stability may be provided by anterior plating, obviating the need for a concomitant posterior approach.

Objectives: To evaluate the clinical and radiological outcome following anterior interbody fusion using a femoral cortical allograft packed in the centre with autogenous iliac graft combined with posterior pedicle fixation.

Design: A prospective study of 30 consecutive adult patients diagnosed with lumbar degenerative disc disease.

Summary of background data: Various fusion options have been described in the literature with various clinical and radiological outcomes. Narrowing of the disc space is thought to be the primary cause of all the potential secondary spondylotic changes; the ideal corrective surgery would be one that reconstitutes the disc space interval. A hybrid graft consisting of a femoral cortical allograft (FCA) ring packed in the centre with autogenous cancellous iliac graft seems to be an ideal option as one should capitalize on the mechanical strength of the cortical ring and the biological strength of the cancellous autogenous graft.

Methods: 15 patients with failed back surgery, 15 patients with primary degenerative disc disease. Mean age was 43 years. All patients had preoperative radiographs, MRI scanning, discography was not used in this study. All femoral allografts were processed by freeze drying and sterilized using ethylene oxide. The protocol for surgery consisted of:

* Left sided retroperitoneal muscle splitting approach

Results: There were no complications from using the allograft. Intraoperative and postoperative complications were seen in 3 patients. After a minimum follow up of 2 years good clinical outcome was achieved in 83 % using Ricciardi et al criteria, solid fusion was achieved in 98%.

Conclusion: The results in this study continue to support the efficacy of using hybrid interbody grafts to achieve a successful fusion, however there is discrepancy between the radiological and clinical outcome which merits additional investigations

Purpose: Infection of a posterior fixation can lead to a therapeutic dilemma, particularly if the extensive fixation involves a demineralised spine.

Material and methods: From 1998 to 2001, seven patients aged 19 to 76 years (mean 58) were treated with an interbody cage and an autologous graft. Four patients with scoliosis had had prior posterior surgery (mean five operations, range 3 – 9 operations). All had exhibited non-union with repeated fistulisation at each prior anterior approach, in four cases with meti-R Staphylococcus associated once with a Streptococcus and twice with an Enterococcus. Three patients suffered severe radicular pain. Three of the post-trauma patients had undergone revision procedures to remove the posterior implants. All had developed nonunion with total loss of the initial correction in two cases, one with septic instability concerning the level above the fixation. Both infections were caused by meti-R Staphylococcus, associated with an Enterococcus in one case. Two persistent posterior fistulae had been reoperated earlier. The grafts involved one to four levels with no new posterior fixation except for one patient (two accesses to the thoracolumbar junction, five lumbosacral fusions, immobilisation for four to six months with a corset). Mean duration of postoperative antibiotics was four months (3–12 months). Fusion was confirmed by the radiological aspect of the grafts on the scan obtained at a mean 22 months follow-up (minimum follow-up 12 months).

Results: There were no cases of anterior infection except for one post-trauma patient where a posterior screw touched the disc (reactivation of infection without anterior abscess, posterior approach for revision and final fusion in kyphosis). There was no appreciable improvement in correction, but the six other patients fused with a clear clinical improvement (removal of rigid corset, reduction of antalgesics, mean time 6 months). Improvement was observed in the three patients with radicular pain. One patient who had undergone three prior anterior operations underwent the minimally invasive posterior revision with no particular intraoperative problem but later presented ureteral necrosis (secondary nephrectomy).

Discussion: This interbody grafting strategy is a possible solution to salvage mechanical failures subsequent to recurrent severe infection often due to multiple germs. The technique is more difficult in older patients with complex malformations. A positive disc sample is a factor of less satisfactory outcome. In the event of prior anterior revision, an ureteral catheter is advisable to limit the risk of necrosis. Use of intersomatic cages is not a problem and has allowed us to achieve primary and secondary stability in these patients with poor bone stock and this without supplementary infection problems.

To compare the effectiveness of ALIF, using the Hartshill Horseshoe cage, and Graf ligamentoplasty for stabilisation of comparable severity of degenerative disc disease.

Between 1995 and 1997, 27 patients who had single level ALIF with Hartshill Horseshoe cage [group A], and 28 patients who had single level Graf ligamentoplasty [group B] were assessed by Oswestry disability index, a subjective score, Zung Depression Scale [ZDS], and Modified Somatic Perception Questionnaire [MSPQ]. The two groups were similar in age and sex distribution. The patients were randomized, and procedures were all undertaken primarily for symptoms of back pain, although some patients in each group reported some leg pain. No patients with the ALIF group had any MRI evidence of neurological compromise. Where there was any degeneration at more than 1 level, discography was undertaken (8 patients in each group) confirming an isolated pain source at a single level. The duration of back symptoms and leg symptoms in the two groups was similar. There was some difference in the distribution of the MRI grade of disc degeneration between the 2 groups, but this did not reach statistical significance. Following is the characteristic of the 2 groups:

In this group, Graf ligamentoplasty procedure had a statistically significant better outcome than ALIF with the Hartshill horseshoe cage.

This may be due to the retention of some degree of normal mobility of the affected segments after stabilisation with Graf ligaments. However, at a minimum follow-up of 2 years, these represent only medium term results. There is a potential for a change in the outcome in the long term.

Introduction: Lumbar fusion is one of the most frequently recommended treatments in spinal surgery, whereas ALIF and PLF are discussed controversially. This prospective and consecutive study examined if complications and rehabilitation differed between patients with a degenerated lumbar spine, who had been treated with ALIF or PLF.

Methods: Between 04/2002 and 12/2005 clinical data of 39 patients, who were treated with ALIF, and of 296 patients, who received PLF, were submitted to the European Spine Register SSE Spine Tango. Complications and rehabilitation process were documented after a median follow-up time of 9 weeks (IQR 8–24 weeks). Analysis was performed with non-parametric tests. The study corresponds with an EBM-level 3.

Results: The median age of patients with ALIF was 56 years (IQR 37-66 yrs) vs. 64 yrs in the PLF group (IQR 54–72 yrs) with a male to female ratio 10:29 vs. 108:188.

Patients after ALIF and PLF had an even complication rate (5/39 vs. 26/296, p = 0,41). The types of complications in the ALIF group were less severe (sensory and motoric disturbance vs. implant failure and implant malposition). All five patients needing reintervention belonged to the PLF group. Three quarters of all patients underwent rehabilitation. The proportion of patients with outpatient rehabilitation was higher in the ALIF group (14/39 vs. 50/296 patients, p = 0,05).

Conclusions: Patients with degenerative lumbar spine disease have a less severe type of complications after ALIF than after PLF, whereas the complication rate is even. Concerning the higher proportion of patients with outpatient rehabilitation in the ALIF group, one has to consider their lower age compared with patients in the PLF group. Except for the severeness of complications and the proportion of outpatient rehabilitation one cannot conclude an advantage of either of the two surgical methods.

Study Design

Single surgeon prospective cohort with radiological follow-up.

Stand-alone anterior lumbar interbody fusion (ALIF) provides the opportunity to avoid supplemental posterior fixation. This may reduce morbidity and complication rate, which is of special interest in patients with reduced bone mineral density (BMD). This study aims to assess immediate biomechanical stability and radiographic outcome of a stand-alone ALIF device with integrated screws in specimens of low BMD. Eight human cadaveric spines (L4-sacrum) were instrumented with SynFix-LR™ (DePuy Synthes) at L5/S1. Quantitative computed tomography was used to measure BMD of L5 in AMIRA. Threshold values proposed by the American Society of Radiology 80 and 120 mg CaHa/mL were used to differentiate between Osteoporosis, Osteopenia, and normal BMD. Segmental lordosis, anterior and posterior disc height were analysed on pre- and postoperative radiographs (Fig 1). Specimens were tested intact and following instrumentation using a flexibility protocol consisting of three loading cycles to ±7.5 Nm in flexion-extension, lateral bending, and axial rotation. The ranges of motion (ROM) of the index level were assessed using an optoelectronic system. BMD ranged 58–181mg CaHA/mL. Comparison of pre- and postoperative radiographs revealed significant increase of L5/S1 segmental lordosis (mean 14.6°, SD 5.1, p < 0.001) and anterior disc height (mean 5.8mm, SD 1.8, p < 0.001), but not posterior disc height. ROM of 6 specimens was reduced compared to the intact state. Two specimens showed destructive failure in extension. Mean decrease was most distinct in axial rotation up to 83% followed by flexion-extension. ALIF device with integrated screws at L5/S1 significantly increases segmental lordosis and anterior disc height without correlation to BMD. Primary stability in the immediate postoperative situation is mostly warranted in axial rotation. The risk of failure might be increased in extension for some patients with reduced lumbar BMD, therefore additional posterior stabilization could be considered. For any figures or tables, please contact the authors directly

Introduction. The placement of a large interbody implant allows for a larger surface area for fusion, vis a vis, via retroperitoneal direct anterior, antero-lateral and lateral approaches. At the same time, spinal navigation facilitates a minimally invasive fixation for inserting posterior pedicle screws. We report on the first procedures in the United Kingdom performed by a single-surgeon at a single- centre using navigated robot-assisted spine surgery without the need for guide-wires. Materials and Methods. Whilst positioned in the supine or lateral position, a routine supine anterior lumbar interbody fusion (ALIF), and/or antero-lateral ALIF (AL-ALIF) and/or lateral lateral interbody fusion (LLIF) is performed. The patient is then turned prone or kept in the single lateral position (SPL) for insertion of the posterior screws performed under robotic guidance. Intraoperative CT scan 3D images captured then are sent to the Robotic software platform for planning of the screw trajectories and finally use again at the end of the procedure to confirm screw accuracy. We identified 34 consecutive patients from October 2019 to January 2020 who underwent robotic assisted spine surgery. The demographic, intraoperative, and perioperative data of all these patients were reviewed and presented. Results. Of the 34 patients, 65 levels were treated in total using 204 screws. Of the 21 patients (60%) who underwent single-level fixation, 14 of them (67%) were treated at the L5/S1 level, 3 at L3/L4, 3 at L4/L5 and 1 at L2/L3 level. The remaining 13 patients (40%) underwent multi-level fixation, of which 4 were adult scoliosis. 15 underwent a supine ALIF approach, 1 underwent AL-ALIF, 8 patients underwent combined LLIF and AL-ALIF approach in a lateral decubitus, whilst 9 underwent pure LLIF approach (of which 3 patients were in the single position lateral) and one patient had previous TLIF surgery. The average estimated blood loss was 60 cc. The average planning time was 10 min and the average duration of surgery was 50 min. The average patient age was 54 years and 64% (22/34) were male. The average BMI was 28.1 kg/m. 2. There were no re-interventions due to complications or mal positioned screws. Conclusion. Minimally invasive spine surgery using robot-assisted navigation yields an improved level of accuracy, decreased radiation exposure, minimal muscle disruption, decreased blood loss, shorter operating theatre time, length of stay, and lower complication rates. Further follow-up of the patients treated will help compare the clinical outcomes with other techniques