The presacral retroperitoneal approach for axial lumbar interbody fusion (presacral ALIF) is not widely reported, particularly with regard to the mid-term outcome. This prospective study describes the clinical outcomes, complications and rates of fusion at a follow-up of two years for 26 patients who underwent this minimally invasive technique along with further stabilisation using pedicle screws. The fusion was single-level at the L5-S1 spinal segment in 17 patients and two-level at L4–5 and L5-S1 in the other nine. The visual analogue scale for pain and Oswestry Disability Index scores were recorded pre-operatively and during the 24-month study period. The evaluation of fusion was by thin-cut CT scans at six and 12 months, and flexion-extension plain radiographs at six, 12 and 24 months. Significant reductions in pain and disability occurred as early as three weeks postoperatively and were maintained. Fusion was achieved in 22 of 24 patients (92%) at 12 months and in 23 patients (96%) at 24 months. One patient (4%) with a pseudarthrosis underwent successful revision by augmentation of the posterolateral fusion mass through a standard open midline approach. There were no severe adverse events associated with presacral ALIF, which in this series demonstrated clinical outcomes and fusion rates comparable with those of reports of other methods of interbody fusion

To assess the effectiveness of dynamic stabilisation as a treatment for discogenic pain compared to standard treatment of interbody fusion. All patients were referred for a 2 year back-pain management programme. Patients with continued pain following conservative treatment underwent discography & MRI. Patients with painful degenerate discs on the above investigations were selected. Patients underwent interbody fusion (PLIF/TLIF) or dynamic stabilisation. Mean follow-up was 24 months with a minimum follow-up of 12 months. All patients had pre-operative ODI and VAS scores. Patients were then sent further questionnaires at 6 month intervals. The mean improvement in ODI following dynamic stabilisation was 20% (-20% → 56%), the mean improvement in the pain score was 2.4 (0→8). The mean improvement in ODI following interbody fusion was 11% (-14%→48%), the mean improvement in the pain score was 2.6 (-4→9). 10 patients in the dynamic stabilisation group had a greater than 20% improvement in ODI, 7 patients in the interbody fusion group had similar results. The above results demonstrate that dynamic stabilisation is at least as effective at treating discogenic pain as interbody fusion. The results however do question the validity of either interbody fusion (PLIF/TLIF) or dynamic stabilisation in the management of discogenic pain

Objective. To assess the effectiveness of dynamic stabilisation as a treatment for discogenic pain compared to standard treatment of interbody fusion. Study Design & Subjects. All patients were referred for a 2 year back-pain management programme. Patients with continued pain following conservative treatment underwent discography & MRI. Patients with painful degenerate discs on the above investigations were selected. Patients underwent interbody fusion (PLIF/TLIF) or dynamic stabilisation. Mean follow-up was 24 months with a minimum follow-up of 12 months. Outcome Measures. All patients had pre-operative ODI and VAS scores. Patients were then sent further questionnaires at 6 month intervals. Results. The mean improvement in ODI following dynamic stabilisation was 20% (-20% → 56%), the mean improvement in the pain score was 2.4 (0→8). The mean improvement in ODI following interbody fusion was 11% (-14%→48%), the mean improvement in the pain score was 2.6 (-4→9). 10 patients in the dynamic stabilisation group had a greater than 20% improvement in ODI, 7 patients in the interbody fusion group had similar results. Conclusion. The above results demonstrate that dynamic stabilisation is at least as effective at treating discogenic pain as interbody fusion. The results however do question the validity of either interbody fusion (PLIF/TLIF) or dynamic stabilisation in the management of discogenic pain

We carried out a prospective study to determine whether the addition of a recombinant human bone morphogenetic protein (rhBMP-2) to a machined allograft spacer would improve the rate of intervertebral body fusion in the spine. We studied 77 patients who were to undergo an interbody fusion with allograft and instrumentation. The first 36 patients received allograft with adjuvant rhBMP-2 (allograft/rhBMP-2 group), and the next 41, allograft and demineralised bone matrix (allograft/demineralised bone matrix group). Each patient was assessed clinically and radiologically both pre-operatively and at each follow-up visit using standard methods. Follow-up continued for two years. Every patient in the allograft/rhBMP-2 group had fused by six months. However, early graft lucency and significant (> 10%) subsidence were seen radiologically in 27 of 55 levels in this group. The mean graft height subsidence was 27% (13% to 42%) for anterior lumbar interbody fusion, 24% (13% to 40%) for transforaminal lumbar interbody fusion, and 53% (40% to 58%) for anterior cervical discectomy and fusion. Those who had undergone fusion using allograft and demineralised bone matrix lost only a mean of 4.6% (0% to 15%) of their graft height. Although a high rate of fusion (100%) was achieved with rhBMP-2, significant subsidence occurred in more than half of the levels (23 of 37) in the lumbar spine and 33% (6 of 18) in the cervical spine. A 98% fusion rate (62 of 63 levels) was achieved without rhBMP-2 and without the associated graft subsidence. Consequently, we no longer use rhBMP-2 with allograft in our practice if the allograft has to provide significant structural support

To evaluate the findings of fusion of titanium interbody cages in a sheep lumbar interbody fusion model. Six sheep underwent lumbar discectomy and fusion at L3-L4 throught transperitoneal approach. An cervical threaded expanding and cylindrical cage packed with bone autografts was placed into intervertebral disc space. The sheeps were killed at 9, 12 and 18 months after surgery. The lumbar spines were excised, trimmed of residual musculature and underwent to plain radiographs and CT scans. The spines were dissected and sectioned using the EXAKT microgrinding device creating parasagittal and coronal sections. Plain radiographs demonstrated no lucent lines around the implants and no change in disc height. CT scans showed mineralized bone within the cages and bone in growth wit anterior bony bridging outside of the cages. Histologic characterizations indicated the presence of mature lamellar bone with osteonic systems filling the central area of the cage. Bone in growth on the surface of the implant is present near the fenestrations alone. A membrane of fibrous tissue layer is present on the external surface of any cage separating bone from the implant. Expanding titanium cages have shown mechanical and biological validity to achieve an optimal interbody fusion. Design of the cage showed a decisive role to provide superior endplate-to-endplate contact for unsurpassed strenght and stability and to agree the achievement of the interbody fusion across its fenestrations

Aims. The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique. Methods. This was a multicentre retrospective study involving consecutively enrolled patients who underwent L4-L5 LLIF by seven surgeons at seven institutions in three countries over a five-year period. The demographic details of the patients and the details of the surgery, reoperations and complications, including femoral and non-femoral neuropraxia, thigh pain, weakness of hip flexion, and abdominal complications, were analyzed. Neurological and psoas-related complications attributed to LLIF or posterior instrumentation and persistent symptoms were recorded at one year postoperatively. Results. A total of 517 patients were included in the study. Their mean age was 65.0 years (SD 10.3) and their mean BMI was 29.2 kg/m. 2. (SD 5.5). A mean of 1.2 levels (SD 0.6) were fused with LLIF, and a mean of 1.6 (SD 0.9) posterior levels were fused. Femoral neuropraxia occurred in six patients (1.2%), of which four (0.8%) were LLIF-related and two (0.4%) had persistent symptoms one year postoperatively. Non-femoral neuropraxia occurred in nine patients (1.8%), one (0.2%) was LLIF-related and five (1.0%) were persistent at one year. All LLIF-related neuropraxias resolved by one year. A total of 32 patients (6.2%) had thigh pain, 31 (6.0%) were LLIF-related and three (0.6%) were persistent at one year. Weakness of hip flexion occurred in 14 patients (2.7%), of which eight (1.6%) were LLIF-related and three (0.6%) were persistent at one year. No patients had bowel injury, three (0.6%) had an intraoperative vascular injury (not LLIF-related), and five (1.0%) had ileus. Reoperations occurred in five patients (1.0%) within 30 days, 37 (7.2%) within 90 days, and 41 (7.9%) within one year postoperatively. Conclusion. LLIF involving the L4-L5 disc level has a low rate of persistent neurological, psoas-related, and abdominal complications in patients with the appropriate indications and using a standardized surgical technique. Cite this article: Bone Joint J 2024;106-B(1):53–61

1. At the present stage of our experience, when 150 patients have been analysed over a period of five years, the conclusion has been reached that anterior interbody fusion in the lower lumbar spine is a procedure which should be added to our surgical armamentarium for use in selected cases. 2. Patients suffering from chronic intervertebral disc degeneration whose main symptoms are recurrent incapacitating backache derive the most benefit from this procedure. 3. When used as a salvage operation in patients who have had previous unsuccessful laminectomy or posterior fusion, good results can be expected. 4. In patients with spondylolisthesis anterior interbody fusion should be confined to cases in which the vertebral bodies have not slipped forward more than one-third

Aims. We compared the clinical and radiological outcomes of using a polyetheretherketone cage with (TiPEEK) and without a titanium coating (PEEK) for instrumented transforaminal lumbar interbody fusion (TLIF). Materials and Methods. We conducted a randomised clinical pilot trial of 40 patients who were scheduled to undergo a TLIF procedure at one or two levels between L2 and L5. The Oswestry disability index (ODI), EuroQoL-5D, and back and leg pain were determined pre-operatively, and at three, six, and 12 months post-operatively. Fusion rates were assessed by thin slice CT at three months and by functional radiography at 12 months. Results. At final follow-up, one patient in each group had been lost to follow-up. Two patients in each of the PEEK and TiPEEK groups were revised for pseudarthrosis (p = 1.00). The rate of complete or partial fusion at three months was 91.7% in both groups. Overall, there were no significant differences in ODI or in radiological outcomes between the groups. Conclusion. Favourable results with identical clinical outcomes and a high rate of fusion was seen in both groups. The titanium coating appears to have no negative effects on outcome or safety in the short term. A future study to determine the effect of titanium coating is warranted. Cite this article: Bone Joint J 2017;99-B:1366–72

We evaluated the efficacy of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E-BMP-2) in a mini-pig model of spinal anterior interbody fusion. A total of 14 male mini-pigs underwent three-level anterior lumbar interbody fusion using polyether etherketone (PEEK) cages containing porous hydroxyapatite (HA). Four groups of cages were prepared: 1) control (n = 10 segments); 2) 50 μg E-BMP-2 (n = 9); 3) 200 μg E-BMP-2 (n = 10); and 4) 800 μg E-BMP-2 (n = 9). At eight weeks after surgery the mini-pigs were killed and the specimens were evaluated by gross inspection and manual palpation, radiological evaluation including plain radiographs and micro-CT scans, and histological analysis. Rates of fusion within PEEK cages and overall union rates were calculated, and bone formation outside vertebrae was evaluated. One animal died post-operatively and was excluded, and one section was lost and also excluded, leaving 38 sites for assessment. This rate of fusion within cages was 30.0% (three of ten) in the control group, 44.4% (four of nine) in the 50 μg E-BMP-2 group, 60.0% (six of ten) in the 200 μg E-BMP-2 group, and 77.8% (seven of nine) in the 800 μg E-BMP-2 group. Fusion rate was significantly increased by the addition of E-BMP-2 and with increasing E-BMP-2 dose (p = 0.046). In a mini-pig spinal anterior interbody fusion model using porous HA as a carrier, the implantation of E-BMP-2-loaded PEEK cages improved the fusion rate compared with PEEK cages alone, an effect that was significantly increased with increasing E-BMP-2 dosage. Cite this article: Bone Joint J 2013;95-B:217–23

Anterior decompression and adequate spine fixation in patients with cervical radiculopathy and myelopathy are essential for functional restoration of cervical spine. In this study, we performed evaluation and comparative radiological assessment of several types of spinal implants in terms of bone block formation, sagittal alignment and effectiveness as a structural support. Materials and Methods: From 1993 to 2003, 165 patients with radiculopathy and myelopathy due to degenerative disease of cervical spine were operated on. The age of patients was 32–74 years (mean age 57, 8). The interbody fusion was performed by several methods. Group1. Autograft – 91 patients. Group 2. TiNi alloy cages – 74 patients. Group 3. Varilift expandable cages without plate fixation – 22 patients. Group 4. Verilift cages with plate fixation – 8 patients. Group 5. Bone substitute spacer and plate fixation – 3 patients. Results: In groups 1 and 2, the bone and bone-metal block was formed during the first 3–4 months after surgery in all patients. There were no cases of bone resorbtion around the TiNi cages or loosening of the device. In patients with one-level (15 patients) interbody fusion by Varilift cages (group 3); formation of the bone block during the same time period was observed in 14 out of 15 patients. In cases with two-level fusion (7 patients), the bone block at the second level was not formed for longer than 6 months. There were 7 cases of subsiding and segmental kyphosis. In group 4, we did not detect any cases of loosening, subsiding or segmental kyphosis. In group 5, no bone block formation was observed after 6 months despite plate fixation. Conclusions: A high fusion rate was achieved after a single or multi-level discectomy and interbody fusion by autograft and TiNi cages, which did not subside due to their design and superelasticity and can therefore be used without plate fixation. Varilift cages were also very effective, but if used without plate fixation may be associated with subsiding effect. The use of the bone substitute spacer is questionable in cervical spine surgery. Cervical plate fixation is effective as a prophylactic measure against segmental kyphosis in all types of interbody fusion

Purpose: Interbody fusion cages have met with great success as an adjunct in the treatment of painful degenerative disc disease. One of the limitations is the need for the use of autogenous cancellous bone graft. In preclinical studies recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered in a variety of carriers has been shown to be an effective substitute for autogenous bone, resulting in more rapid and reliable healing than that seen in control groups. The goal of this study was to report the early results of the first human trial attempting to use rhBMP-2 in interbody fusion cages. Methods: This study was an FDA approved IDE multicenter pilot study. From 1/97 to 4/97, 14 patients were entered into a prospective, randomized trial. All patients had single level lumbar degenerative disc disease that was refractory to prolonged nonoperative care and were candidates for anterior interbody fusion of L4-5 or L5-S1. After consent, patients were randomized to either the control group (N-3) and received autogenous bone inside tapered titanium fusion cages (NOVUS LT, Sofamor Danek Memphis, TN) or to the investigational group (N = 11) and received rhBMP-2 (1.5 mg/ml)(Genetics Institute, Cambridge MA) delivered in a collagen sponge (Helistat, Integra Life Sciences, Plainsboro, NJ) inside the fusion cages. Depending on the size, the sponge in each cage was soaked with from 1.3 to 2.6 ml of the rhBMP2 solution. Patients were followed at regular intervals with plain x-ray, CT scan with reconstruction, and a full panel of blood tests. Radiographs were reviewed by an independent blinded radiologist with fusion defined as < 5 degrees of sagittal motion, absence of radiolucent lines, and presence of continuous bone through the cages. Clinical results were assessed using an outcomes questionnaire including the SF-36 general health status and Oswestry low back specific instruments. Results: All 14 patients were available for 1-year follow-up. No cages displaced and no further surgeries were required. Mean hospital stay was 2.0 days for the rhBMP-2 patients compared to 3.3 days for the autograft controls. Of the 11 rhBMP2 patients, 10 of 11 were judged to be fused at 3 months. At 6 months and 1-year all 11 rhBMP-2 patients were noted to have a solid arthrodesis. Of the 3 control patients, 2 had solid arthodesis and one had an apparent nonunion at 1 year. On sagittal CT scan reconstruction new bone growth was seen throughout and anterior to the cages that were filled with rhBMP-2. No patients had bone formation outside of the desired area. The control patient with the nonunion had a halo surrounding the cage on the sagittal CT reconstruction. This patient had persistence of low back pain. Compared to preop, the Oswestry scores at 3 months were decreased in the rhBMP-2 group (39 to 30) compared to controls which were increased (35 to 43) and both mean scores were similar at 6 months (28 and 27). Conclusion: The preliminary results from this clinical trial with rhBMP-2 inside interbody fusion cages were excellent and support a larger pivotal trial. The arthrodesis was found to occur more rapidly and reliably than in the controls, although the sample size was limited. In addition to faster bone healing, a major advantage was the elimination of bone graft donor site morbidity and realization of decreased hospital stay. No evidence of excessive bone formation or systemic complications occurred. Moreover, this study provides one of the first demonstrations of consistent and unequivocal osteoinduction by a recombinant growth factor in humans

Introduction Anterior column reconstruction and fusion remains the gold standard of treatment for a number of spinal pathologies. One of the challenges of interbody fusions cages is the footprint of the cage reducing the surface area of endplate available for fusion. Biodegradable polymer implants will over time present a greater area for fusion and may help to reduce problems such as stress shielding, particulate debris and retained foreign body response. Resorbable cages have been have been prepared from a number of different materials, including inorganic composites (eg hydroxyapatite / tricalcium phosphate) and polymers (Poly L-lactide-co-D,L-lactide (PDLLA)). However all of the current options for interbody fusion have reported deficiencies or complications. The synthesis, mechanical properties, and degradation behaviour of two novel biopolymers are presented and the applicability for use as materials in interbody fusion devices is discussed. Methods Methacrylated adipic anhydride (MAA) and methacrylated sebacic anhydride (MSA) pre-polymers were synthesized by melt condensation. Conversion of the acid to the anhydride was confirmed using 1H nuclear magnetic resonance (NMR) (Bruker, Alexandria, NSW) and FT- Infrared spectroscopy (Nicolet, Waltham MA). These pre-polymers were subsequently co-polymerized with methyl methacrylate (MMA) and 0.25 wt% benzoyl peroxide at 65oC for 16hrs and post-cured at 120oC under vacuum for 2 hrs to form biodegradable networks. The co-polymerization behaviour was monitored by FT-Raman spectroscopy. The compressive mechanical properties of the polymer were determined using an Instron 5567 (Bayswater Vic.). The polymer networks were degraded in phosphate buffered saline (PBS) with various amounts of MAA and MSA. Results The formation of the pre-polymer was confirmed with the observation of NMR peaks at 5.8 and 6.2 ppm and FT-IR peaks at 1637cm-1. Copolymerization was followed with consecutive FT-IR acquisitions with 100% conversion achieved between 10 and 30 hrs depending on the ratio of MMA to MSA or MAA. Increasing the fraction of methacrylated anhydride slowed the reaction rate. The compressive strength of the MAA and MSA based copolymers was measured as a function of anhydride concentration. Compressive strength for MMA increased (90±9 to 140±10 Mpa) in an approximately linear manner for MAA concentrations from 10 to 40 wt.% but decreased markedly for MAA concentration of 45% (62±14 Mpa). The compressive strength of MSA decreased exponentially for concentrations ranging from 10 to 45 wt.% (140±18 to 39±1 Mpa). Discussion The use of poly-L-lactic acid in lumbar interbody cages has been shown to be mechanically feasible with the mechanical strength of the cage material reported to be 93 Mpa (. 1. ). The material described here has controlled mechanical properties in the required range as well as a degradation behaviour that lends itself better to spinal applications than current materials

The purpose of the study was to determine the effectiveness of rhBMP-2 when applied to an absorbable collagen sponge for interbody fusion with allograft spacers. Seventy-seven consecutive patients requiring inter-body fusion with one hundred and eighteen levels were included in the study. In thirty-six patients cervical or lumbar interbody fusions were performed using allograft and rhBMP-2. In the remaing allograft was used with demineralised bone matrix. In patients undergoing anterior cervical decompression and fusion (ALIF) machined allograft spacers were supplemented with anterior locking plates. In those scheduled for anterior lumbar inter-body fusion (ALIF) or transforaminal lumbar interbody fusion (TLIF), machined allograft spacers were supplemented with posterior pedicle screw constructs. There were no stand alone ALIF procedures. All patients undergoing surgery were assessed preoperatively and at two weeks, six weeks, three, six, twelve, twenty-four months following surgery.Their Oswestry disability index (ODI) questionaires, Visual analogue scale (VAS) scores and a pain diagram were recorded. Radiographic measurements were made on the electronic public access computer system (EPACS). All patients with allograft plus rhBMP-2 showed radiographic evidence of fusion by six months following surgery. The allograft with demineralised bone matrix group took considerably longer to achieve the same radiographic end plate appearance. Subsidence was obvious on radiographs in greater than 50% of cases with allograft and rhBMP-2 at three months. It was noted to occur between six weeks and three months and there was no significant subsidence after six months. This was statistically significant with a p< 0.0001 (fisher exact test). The average subsidence for the entire rhBMP-2 group at twelve months was 16.5%(SE 2.5% and range 0–58%) and for the allograft and bone matrix group was 4.6%(SE.74% range 0–15%)with a p< 0.0001 (independant t test). Although high rates of fusion can be accomplished with allograft and rhBMP-2 (100%), significant subsidence occurs in greater than 50% of lumbar spine cases and 30% of cervical spine cases. This is possibly a result of early bone turnover with loss of structural support of the allograft spacer and end plate resorption

RhBMP2 was used in thirty-six consecutive patients requiring interbody fusion with fifty-five levels (thirteen patients twenty levels ALIF, twelve patients seventeen levels TLIF, eleven patients eighteen levels ACDF) using anterior cervical locking plates and lumbar posterior pedicle screw constructs. All patients showed radiographic fusion at six months. Early lucency, subsidence, and increased pain occurred between six weeks and three months in 70% of ALIFS, 53% of TLIFS and 33% of ACDF’s. The average subsidence was 27% in ALIFS, 24% in TLIFS, and 53% in ACDF. Pain improved by the sixth month. We recommend alternative structural support when using RhBMP2. To determine effectiveness of RhBMP2 in interbody fusion with machined allograft spacers (MTF Synthes Spine USA femoral ring, TLIF and fibular ring cervical spacers). A prospective study of thirty-six consecutive patients requiring interbody fusion with fifty-five levels (thirteen patients twenty levels ALIF, twelve patients seventeen levels TLIF, eleven patients eighteen levels ACDF). Machined allograft spacers and RhBmp2 were supplemented with anterior locking plates in the cervical spine while the lumbar segments were supplemented posterior pedicle screws constructs. Patients were followed at two weeks, six weeks, three months, six months, one year. Patients were examined, had xrays, completed Oswestry scores, pain diagrams, and VAS for pain preoperatively and at every follow up appointment. All the patients showed radiographic evidence of fusion at six months after surgery. Early lucency and subsidence of allografts was observed in 70% of ALIFS, 53% of TLIFS and 33% of ACDF’s. The average subsidence was 27% (range13–42%) in ALIFS, 24% in TLIFS (range 13–40%), and 53% in ACDF. Subsidence and reporting of increased pain occurred between the six- week and three month follow up after which patients improved. Although high rates of early fusion can be accomplished with allograft spacers and rhBMP2 significant subsidence occurs in greater than 50% of lumbar cases and 30% of cervical cases due to early turnover and loss of structural support of the allograft. We recommend alternative structural support when using RhBMP2

The management of discogenic pain continues to be controversial. The results for operative and non-operative management are variable. This study aims to look at the results of interbody fusion versus dynamic stabilisation in patients with discogenic pain. Diagnosis was made by use of MRI and provocative discography. All patients had pre-operative Visual Analogue Scores and Oswestry Disability Index scores. Patients were then assessed in the post-operative period at 6 months, 1 year and 2 years. Case matched series with 19 patients in each group with a mean follow-up of 24 months. In comparison of both techniques there were no statistically significant differences but the dynamic stabilisation group had improved outcomes with both measures. The results did raise some further issues, as several patients in each group were either worse or had no significant improvement following surgery. In conclusion this paper raises concerns regarding the use of surgery for patients with discogenic pain. If surgery is however considered, dynamic stabilisation is a valid alternative to interbody fusion

Objective: To determine if a porous, coralline-derived hydroxyapatite block (ProOsteon 500. TM. , Interpore, Irvine, CA) is a suitable substitute for tricortical iliac crest autograft in cervical interbody fusion. Design: A prospective randomised trial with two-year follow-up comparing clinical and radiographic outcomes in patients receiving either iliac crest or hydroxyapatite grafts in cervical interbody fusion. Subjects: Twenty-nine patients undergoing cervical fusion and anterior plating were randomised to receive either iliac crest (Group I) or hydroxyapatite (Group II) interbody grafts. Fourteen patients (19 grafts) in Group I and twelve patients (18 grafts) in Group II were available for final analysis. Both groups were similar with respect to age, sex, diagnosis and levels fused. Outcome Measures: The SF-36 and Oswestry Disability Index were used to measure clinical outcome. Post-op and final follow-up radiographs were analysed for graft fragmentation, loss of height, loss of angular alignment and hardware failure to assess structural integrity of the graft. Computed or plain tomography was used to evaluate fusion. Results: Groups I and II demonstrated improvement in preoperative scores for bodily pain (p=. 016 and. 016 respectively) and physical functioning (p=. 050 and. 016 respectively) at final follow-up. There was no significant difference in SF-36 and Oswestry scores between the two groups. Successful radiographic fusion was similar in both groups (79% in Group I and 76% in Group II). Graft fragmentation occurred in 89% of the hydroxyapatite grafts and 11% of the autografts (p=. 001). Greater than 2mm of graft height and 3° of segmental lordosis were lost in 55% of hydroxyapatite grafts vs. 11% of autografts (p=. 009). One patient in Group II and none in Group I required revision surgery for graft failure. The high rate of early radiographic failure in the hydroxyapatite grafts prompted suspension of further enrolment in the clinical trial. Conclusions: ProOsteon 500 coralline hydroxyapatite blocks do not possess adequate structural integrity to resist axial loading and maintain disc height or segmental lordosis during cervical interbody fusion

Aims. Minimally invasive transforaminal lumbar interbody fusion (MITLIF) has been well validated in overweight and obese patients who are consequently subject to a higher radiation exposure. This prospective multicentre study aimed to investigate the efficacy of a novel lumbar localisation system for MITLIF in overweight patients. Patients and Methods. The initial study group consisted of 175 patients. After excluding 49 patients for various reasons, 126 patients were divided into two groups. Those in Group A were treated using the localisation system while those in Group B were treated by conventional means. The primary outcomes were the effective radiation dosage to the surgeon and the exposure time. Results. There were 62 patients in Group A and 64 in Group B. The mean effective dosage was 0.0217 mSv (standard deviation (. sd. ) 0.0079) in Group A and 0.0383 mSv (. sd. 0.0104) in Group B (p <  0.001). The mean fluoroscopy exposure time was 26.42 seconds (. sd. 5.91) in Group A and 40.67 seconds (. sd. 8.18) in Group B (p < 0.001). The operating time was 175.56 minutes (. sd. 32.23) and 206.08 minutes (. sd. 30.15) (p < 0.001), respectively. The mean pre-operative localisation time was 4.73 minutes (. sd. 0.84) in Group A and 7.03 minutes (. sd. 1.51) in Group B (p < 0.001). The mean screw placement time was 47.37 minutes (. sd. 10.43) in Group A and 67.86 minutes (. sd. 14.15) in Group B (p < 0.001). The pedicle screw violation rate was 0.35% (one out of 283) in Group A and 2.79% (eight out of 287) in Group B (p = 0.020). Conclusion. The study shows that the localisation system can effectively reduce radiation exposure, exposure time, operating time, pre-operative localisation time, and screw placement time in overweight patients undergoing MITLIF. Cite this article: Bone Joint J 2017;99-B:944–50

Aims. To determine the effectiveness of prone traction radiographs in predicting postoperative slip distance, slip angle, changes in disc height, and lordosis after surgery for degenerative spondylolisthesis of the lumbar spine. Methods. A total of 63 consecutive patients with a degenerative spondylolisthesis and preoperative prone traction radiographs obtained since 2010 were studied. Slip distance, slip angle, disc height, segmental lordosis, and global lordosis (L1 to S1) were measured on preoperative lateral standing radiographs, flexion-extension lateral radiographs, prone traction lateral radiographs, and postoperative lateral standing radiographs. Patients were divided into two groups: posterolateral fusion or posterolateral fusion with interbody fusion. Results. The mean changes in segmental lordosis and global lordosis were 7.1° (SD 6.7°) and 2.9° (SD 9.9°) respectively for the interbody fusion group, and 0.8° (SD 5.1°) and -0.4° (SD 10.1°) respectively for the posterolateral fusion-only group. Segmental lordosis (ρ = 0.794, p < 0.001) corrected by interbody fusion correlated best with prone traction radiographs. Global lumbar lordosis (ρ = 0.788, p < 0.001) correlated best with the interbody fusion group and preoperative lateral standing radiographs. The least difference in slip distance (-0.3 mm (SD 1.7 mm), p < 0.001), slip angle (0.9° (SD 5.2°), p < 0.001), and disc height (0.02 mm (SD 2.4 mm), p < 0.001) was seen between prone traction and postoperative radiographs. Regression analyses suggested that prone traction parameters best predicted correction of slip distance (Corrected Akaike’s Information Criterion (AICc) = 37.336) and disc height (AICc = 58.096), while correction of slip angle (AICc = 26.453) was best predicted by extension radiographs. Receiver operating characteristic (ROC) cut-off showed, with 68.3% sensitivity and 64.5% specificity, that to achieve a 3.0° increase in segmental lordotic angle, patients with a prone traction disc height of 8.5 mm needed an interbody fusion. Conclusion. Prone traction radiographs best predict the slip distance and disc height correction achieved by interbody fusion for lumbar degenerative spondylolisthesis. To achieve this maximum correction, interbody fusion should be undertaken if a disc height of more than 8.5 mm is attained on preoperative prone traction radiographs. Level of Evidence: Level II Prognostic Study. Cite this article: Bone Joint J 2020;102-B(8):1062–1071

Introduction and Objective. Posterior and transforaminal lumbar interbody fusion (PLIF, TLIF) represent the most popular techniques in performing an interbody fusion amongst spine surgeons. Pseudarthrosis, cage migration, subsidence or infection can occur, with subsequent failed surgery, persistent pain and patient’ bad quality of life. The goal of revision fusion surgery is to correct any previous technical errors avoiding surgical complications. The most safe and effective way is to choose a naive approach to the disc. Therefore, the anterior approach represents a suitable technique as a salvage operation. The aim of this study is to underline the technical advantages of the anterior retroperitoneal approach as a salvage procedure in failed PLIF/TLIF analyzing a series of 32 consecutive patients. Materials and Methods. We performed a retrospective analysis of patients’ data in patients who underwent ALIF as a salvage procedure after failed PLIF/TLIF between April 2014 to December 2019. We recorded all peri-operative data. In all patients the index level was exposed with a minimally invasive anterior retroperitoneal approach. Results. Thirty-two patients (average age: 46.4 years, median age 46.5, ranging from 21 to 74 years hold- 16 male and 16 female) underwent salvage ALIF procedure after failed PLIF/TLIF were included in the study. A minimally invasive anterior retroperitoneal approach to the lumbar spine was performed in all patients. In 6 cases (18.7%) (2 infection and 4 pseudarthrosis after stand-alone IF) only anterior revision surgery was performed. A posterior approach was necessary in 26 cases (81.3%). In most of cases (26/32, 81%) the posterior instrumentation was overpowered by the anterior cage without a previous revision. Three (9%) intraoperative minor complications after anterior approach were recorded: 1 dural tear, 1 ALIF cage subsidence and 1 small peritoneal tear. None vascular injuries occurred. Most of patients (90.6%) experienced an improvement of their clinical condition and at the last follow-up no mechanical complication occurred. Conclusions. According to our results, we can suggest that a favourable clinical outcome can firstly depend from technical reasons an then from radiological results. The removal of the mobilized cage, the accurate endplate and disc space preparation and the cage implant eliminate the primary source of pain reducing significantly the axial pain, helping to realise an optimal bony surface for fusion and enhancing primary stability. The powerful disc distraction given by the anterior approach allows inserting large and lordotic cages improving the optimal segmental lordosis restoration

The use of lumbar fusion procedures in the USA and Europe has rapidly increased over the last decade and a large number of these procedures involve the use of bone grafts. Despite of technical progress of spinal surgery and operative materials the risk of vertebral fusion failure occurs in 5 – 35 % of cases. Autografting has been considered the gold standard for bone graft procedures. However, the harvesting from the iliac crest can be associated with short and long-term morbidity in up to 22 % of cases. Main goal of this experimental study was to compare newly developed hybrid biodegradable nanocomposit porous implant (HBNPI) against bone craft from iliac crest as a new and better alternative for lumbar interbody fusion. 24 male pigs 4 months old weighting around 40 Kg were included in our study. These pigs were divided into two study groups depending on fusion method. Group A – 12 pigs underwent lateral lumbal interbody fusion (L2/3) with implantation of iliac crest bonegraft. Group B - 12 pigs underwent lateral lumbal interbody fusion (L2/3) with newly developed HBNPI. Each group were divided into two subgroups from these 6 spines were harvested 8 weeks (subgroup A1, B1) and 6 spines 16 weeks (group A2, B2) after surgery. After sacrifice, the lumbar spines were taking out and micro-CT, biomechanical testing and histomorphological analysis in all groups were performed to evaluate a quality of intervertebral fusion. As controls (group N), 6 cadaveric intact lumbar spines underwent biomechanical, micro-CT and histological testing. All 24 animals recovered from general anesthesia without unusual events. The operations lasted between 50–90 minutes (mean 70) in Group A and between 35–72 minutes (mean 43) in Group B. All of the pigs from group A could stand up and were mobile within 20 hours (range 7–20). When bone graft harvesting was not necessary (group B) this time was shortened, ranging from 1 – 1,5 hour. All pigs from Group A were limping on the first postoperative day. No limping animal was observed in group B. Total body weight of the pigs increased from 37 kg (range 36–40) at the start to 85 (range 80–89) at sacrifice. Biomechanics evaluation shows that extension flexural stiffness values are statistically significantly different between A2 (16 weeks post-implant) and A1 (8 weeks post-implant). Group A2 achieves higher values than Group A1, which is attributed to the adhesion of the implant to the surrounding vertebrae. Similarly, this also applies to groups B2 and B1. The flexural stiffness at group B2 extension is statistically significantly higher than the A2 group and also than the native N group. Biomechanical evaluation supports findings on micro-CT and histological specimens, where both adjacent vertebrae are completely fused in groups B2, unlike in group A2, where there is no or incomplete fusion. Newly developed HBNPI represents new possibility how to do intervertebral fusion, and simultaneous become chance how to improve and accelerate bone healing process against standard procedures