Experiences with using e-learning tools in orthopedics in an uncontrolled field study application.

BACKGROUND: E-learning is widely used in undergraduate medical education and often in blended learning settings for students learning at home. This study should assess the educative value of e-learning tools in orthopedics and traumatology when used under "field" conditions, in comparison with a controlled laboratory-like setting. MATERIALS AND METHODS: Medical students were invited for their voluntary online participation in an uncontrolled study (UCS). They were randomly exposed to digital book chapters or podcasts on four different orthopedic diseases, and then filled in pre-/post-tests and evaluations. Test results indicating insufficient study participation were not included in the subsequent analysis. Results in a gain of knowledge and student's satisfaction were compared to existing data of a randomized controlled trial with the same tools in a laboratory environment (RCT). RESULTS: Among 84 included UCS students and 130 RCT students, podcast learners showed a significantly higher gain of knowledge compared to text learners independent of the learning setting (UCS p<0.011; RCT p<0.001). There were no significant differences in the gain of knowledge for the two different learning tools when comparing each the UCS and RCT settings. Evaluations showed positive ratings for both tools, while podcasts were on the average rated higher than texts were. Significantly more UCS participants (n=46) compared to the RCT (n=34) showed signs of disengagement with the study (p<0.05). DISCUSSION: The findings suggest that it is possible to achieve a similar gain of knowledge with e-learning tools in uncontrolled settings and in RCTs. The role of e-learning materials in voluntary and formative learning settings is of value and should be explored in future studies. LEVEL OF EVIDENCE: III, case-control study.

A New Navigational Tool for Pedicle Screw Placement in Patients With Severe Scoliosis: A Pilot Study to Prove Feasibility, Accuracy, and Identify Operative Challenges.

STUDY DESIGN: Pilot study. OBJECTIVE: To develop and validate the feasibility and accuracy of a newly designed navigational spinal instrument guiding tool for patient-matched thoracic and lumbar pedicle screw placement in patients with severe scoliosis, and to identify intraoperative challenges that may be relevant. SUMMARY OF BACKGROUND DATA: Pedicle screw placement is challenging in severely rotated scoliotic spine with small diameters and asymmetrical shape of the pedicles and vertebrae. Patient-specific drill/positioning guides with preplanned trajectory have been developed as a promising solution in spinal surgery for precise screw insertion. METHODS: In 4 patients with severe scoliosis, navigational templates and models of all vertebrae to be instrumented were manufactured using a computed tomography (CT)-based 3-dimensional model of the thoracic and lumbar spine. The guides were designed differently for thoracic and lumbar segments according to the individual anatomy to achieve an optimal coupling to the surface of the patient's spine, to maximize the stability of the device itself, and to increase user friendliness for the complete screw positioning process. Intraoperative challenges and opportunities for device and process improvements regarding the handling of the guides during the surgery were recorded. Postoperatively, the intrapedicular screw positions were evaluated versus the preoperative plan and evaluated for cortical violation based on CT scans. RESULTS: A total of 76 pedicle screws were implanted (56 thoracic, 20 lumbar). Two screws (2.6%) were assessed to be misplaced intraoperatively and repositioned. Eighty-four percent of the pedicle screws were completely intrapedicular, 96.1% within <2 mm cortical breech. CT scans did not demonstrate medial pedicle violation, or misplaced screw contact to neurovascular structures. No screw-related clinical complaints were reported postoperatively. CONCLUSIONS: The new custom-made positioning guide is a feasible navigational tool that permits a safe and accurate implantation of pedicle screws in patients with severe scoliosis.

Superior Gain in Knowledge by Podcasts Versus Text-Based Learning in Teaching Orthopedics: A Randomized Controlled Trial.

OBJECTIVE: Digital learning (e-learning) has become a firm part of surgical undergraduate education. However, there is still a lack in analyzing e-learning tools in experimental settings without potentially biasing curricular influences. This study should compare students' learning outcome with podcasts versus book texts under laboratory conditions in the field of orthopedics. METHODS: Voluntary medical students were randomly assigned for learning either with a book chapter or a podcast about common orthopedic diseases in an isolated computer room. Before and after intervention, students answered multiple-choice tests and questionnaires about their attitudes and satisfaction. The study was conducted from November 2012 to February 2013. RESULTS: Totally, 130 students were included (55 text users and 75 podcast users, 52 males and 78 females). There was a significant increase in the overall knowledge for both groups (p < 0.001). Podcast users scored significantly better in the posttests (p < 0.021) and achieved a significantly higher gain of knowledge compared to text users (p < 0.001). The evaluation also showed a significantly higher approval of podcasts regarding comprehensibility, teaching efficacy, or fun learning with it (p < 0.05). Females gained significantly more knowledge by the use of texts than males did (p = 0.04), without any sex difference when using podcasts. CONCLUSIONS: This study showed a significantly higher gain of knowledge and higher satisfaction from learning with podcasts compared to book texts among students. Podcasts seem to be beneficial when teaching defined orthopedic topics to medical students. Sex plays an additional independent role in the impact of e-learning tools on students' learning outcome.

Postoperative posterior lumbar muscle changes and their relationship to segmental motion preservation or restriction: a randomized prospective study.

OBJECTIVE: To date, it remains unclear whether the preservation of segmental motion by total disc replacement (TDR) or motion restriction by stand-alone anterior lumbar interbody fusion (ALIF) have an influence on postoperative degeneration of the posterior paraspinal muscles or the associated clinical results. Therefore, the purpose of the present prospective randomized study was to evaluate the clinical parameters and 3D quantitative radiological changes in the paraspinal muscles of the lumbar spine in surgically treated segments and superior adjacent segments after ALIF and TDR. METHODS: A total of 50 patients with chronic low-back pain caused by single-level intervertebral disc degeneration (Pfirrmann Grade ≥ III) and/or osteochondrosis (Modic Type ≤ 2) without symptomatic facet joint degeneration (Fujiwara Grade ≤ 2, infiltration test) of the segments L4-5 or L5-S1 were randomly assigned to 2 treatment groups. Twenty-five patients were treated with a stand-alone ALIF and the remaining 25 patients underwent TDR. For ALIF and TDR, a retroperitoneal approach was used. At 1 week and at 12 months after surgery, CT was used to analyze paraspinal lumbar muscle tissue volume and relative fat content. Residual muscle tissue volume at 12 months and change in the relative fat content were compared between the groups. In addition, clinical parameters (visual analog scale [VAS] for low-back pain and Oswestry Disability Index [ODI] Questionnaire Version 2 for function) were compared. RESULTS: Compared with 1 week after surgery, the radiological analysis at 12 months revealed a small decrease in the posterior muscle volume (the mean decrease was < 2.5%), along with a small increase in the relative fat content (the mean increase was < 1.9%), in both groups at the index and superior adjacent segments. At the adjacent segment, the ALIF group presented significantly less muscle tissue volume atrophy and a smaller increase in fat content compared with the TDR group. At final follow-up, the clinical parameters related to pain and function were significantly improved in both groups compared with 1 week postsurgery, but there were no differences between the groups. CONCLUSIONS: Motion restriction via stand-alone ALIF and motion preservation via TDR both present small changes in the posterior lumbar paraspinal muscles with regard to volume atrophy or fatty degeneration at the index and superior adjacent segments. Therefore, although the clinical outcome was not affected by the observed muscular changes, the authors concluded that the expected negative influence of motion restriction on the posterior muscles compared with motion preservation does not occur on a clinically relevant level.

ALIF and total disc replacement versus 2-level circumferential fusion with TLIF: a prospective, randomized, clinical and radiological trial.

STUDY DESIGN: Prospective, randomized trial. PURPOSE: The treatment of degenerative disc disease (DDD) with two-level fusion has been associated with a reasonable rate of complications. The aim of the present study was to compare (Hybrid) stand-alone anterior lumbar interbody fusion (ALIF) at L5/S1 with total disc replacement at L4/5 (TDR) as an alternative surgical strategy to (Fusion) 2-level circumferential fusion employing transforaminal lumbar interbody fusion (TLIF) with transpedicular stabilization at L4-S1. METHODS: A total of 62 patients with symptomatic DDD of segments L5/S1 (Modic ≥2°) and L4/5 (Modic ≤2°; positive discography) were enrolled; 31 were treated with Hybrid and 31 with Fusion. Preoperatively, at 0, 12, and a mean follow-up of 37 months, clinical (ODI, VAS) and radiological evaluations (plain/extension-flexion radiographs evaluated for implant failure, fusion, global and segmental lordosis, and ROM) were performed. RESULTS: In 26 of 31 Hybrid and 24 of 31 Fusion patients available at the final follow-up, we found a significant clinical improvement compared to preoperatively. Hybrid patients had significantly lower VAS scores immediately postoperatively and at follow-up compared to Fusion patients. The complication rates were low and similar between the groups. Lumbar lordosis increased in both groups. The increase was mainly located at L4-S1 in the Hybrid group and at L1-L4 in the Fusion group. Hybrid patients presented with increased ROM at L4/5 and L3/4, and Fusion patients presented with increased ROM at L3/4, with significantly greater ROM at L3/4 compared to Hybrid patients at follow-up. CONCLUSIONS: Hybrid surgery is a viable surgical alternative for the presented indication. Approach-related inferior trauma and the balanced restoration of lumbar lordosis resulted in superior clinical outcomes compared to two-level circumferential fusion with TLIF.

Minimally invasive TLIF leads to increased muscle sparing of the multifidus muscle but not the longissimus muscle compared with conventional PLIF-a prospective randomized clinical trial.

BACKGROUND CONTEXT: An overload of the paravertebral muscles after surgical intervention is suggested to be the major cause of postoperative pain. In cross-sectional area analyses, increased atrophy of the multifidus muscle (MF) after conventional open versus minimally invasive posterior lumbar interbody fusion (PLIF) has been described. The three-dimensional characteristics of the paravertebral muscles and separate evaluation of the longissimus muscle (LS) have not been addressed in analyses thus far. PURPOSE: The purpose of the present study was to compare the MF and LS volume atrophy and fatty degeneration between single-level minimally invasive transforaminal lumbar interbody fusion (miTLIF) and conventional midline approach-based PLIF (coPLIF) of L4/L5 or L5/S1 at the index and superior adjacent segments. DESIGN: This was a prospective, randomized, controlled, non-blinded study. PATIENT SAMPLE: Fifty patients with single-level segment degeneration (Pfirrmann ≥III and Modic ≥3) of L4/L5 or L5/S1 not requiring decompression were randomly assigned to two groups. OUTCOME MEASURES: Paraspinal lumbar residual muscle tissue volume, change in the relative fat content of MF and LS at the index and superior adjacent segments, and clinical parameters, including a visual analogue scale (VAS) for low back pain and the Oswestry Disability Questionnaire (ODI) were the outcome measures in this study. METHODS: Twenty-five patients were treated with miTLIF, and the remaining patients were treated with coPLIF (both with transpedicular fixation). Clinical scoring was performed preoperatively and at 1 week and 12 months postoperatively, and computed tomography was performed at the latter two follow-ups. RESULTS: The LS damage at the index segment was similar in both groups (3% greater fat content increase in the coPLIF vs. the miTLIF group, p=.032), whereas MF atrophy and degeneration were increased (p<.001) in the coPLIF group. At the adjacent segment, muscle atrophy and increased fatty infiltration (p<.05) were minimal in both muscles but were similar in both groups. Visual analogue scale and ODI scores improved (p<.001), without differences between the groups. CONCLUSIONS: The muscle damage after miTLIF was inferior to that after coPLIF; spatially, however, the muscle sparing was predominantly attributed to the MF and, surprisingly, not to the LS.

Influence of the Type of Sagittal Profile on Clinical Results of Lumbar Total Disk Replacement After a Mean Follow-Up of 39 Months.

STUDY DESIGN: Retrospective analysis of clinical and radiologic data of a prospective cohort study. OBJECTIVE: To research the clinical differences after lumbar total disk replacement (TDR) with respect to the preoperative global and the adaptation at the local sagittal profile (SP) of the spine. SUMMARY OF BACKGROUND DATA: It was suggested that facet loads and degeneration are dependent on epidemiologically defined types of SP. Moreover, the success of TDR was related to segmental facet joint loads. The influences of the preoperative SP or of the changes of the local SP after TDR on the clinical outcome after TDR remain unclear. METHODS: Fifty-two patients included in a prospective cohort study regarding lumbar single-level TDR L4/5 (n=22) or L5/S1 (n=30) because of degenerative disk disease (Modic ≤2 degrees) were clinically (visual analog scale for back, leg, and overall pain; Oswestry Disability Index) and radiologically (extension-flexion radiographs, plain-spine, and whole-spine lateral radiographs in upright standing position) reevaluated after a minimum follow-up of 24 (24-69) months. On the basis of preoperative plain radiographs in upright standing position, patients were retrospectively assigned to 4 groups according to the individual sagittal profile type (SPT). In patients with persistent back pain, a facet infiltration at the index level was performed. RESULTS: For all patients, an SPT could be defined. Global SP did not change compared with the preoperative state. All groups improved clinically over follow-up. At the last follow-up, types 1 and 4 demonstrated significantly inferior scores for pain and function. TDR-induced changes at the superior adjacent segment and the posterior disk height at the index level were also correlated to inferior clinical results. Infiltration test was positive in type 1-4: 67%, 40%, 33%, and 75%, respectively, of the symptomatic patients. CONCLUSIONS: We suggest SPTs 1 and 4 to represent a contraindication for lumbar TDR of levels L4/5 or L5/S1. Local adaptation in the adjacent segment to TDR may influence the clinical outcome as well.

High efficacy and students' satisfaction after voluntary vs mandatory use of an e-learning program in traumatology and orthopedics--a follow-up study.

INTRODUCTION: Within the last decade, e-learning has gained a consistent place in surgical teaching. However, as the use of new programs is often voluntary, more information on the implications of the data regarding user acceptance and knowledge with mandatory use is desirable, especially in the context of the long-term developments of courses. MATERIALS: Starting in 2009, the e-learning program Network for Students in Traumatology and Orthopedics was offered in a voluntary blended learning context. Students' satisfaction and increase in knowledge were evaluated using questionnaires and written tests. With proven effectiveness, the program became a mandatory part of the curriculum, and students' attitudes and gain of knowledge were re-evaluated in 2010 and 2011 to detect differences in voluntary vs mandatory use. RESULTS: In the evaluation questionnaires (n = 108 voluntary vs n = 361 mandatory), the overall appreciation regarding the offerings remained high. Significantly more students felt better prepared for clinical situations (p < 0.001) and asked for e-tutoring (p = 0.025) with mandatory use. In written tests, both voluntary (n = 70) and mandatory (n = 147) users showed significantly increased knowledge (p < 0.001). Starting with a lower base level (p < 0.001), mandatory users had a significantly higher absolute increase compared with voluntary users (p = 0.015), leading to a similar final level. DISCUSSION: The presented blended learning concept was an efficient way to teach students orthopedics and traumatology. Data can support the assumption that even if the voluntary evaluation of e-learning offerings might be subject to a selection bias, the results can serve as a representative impression for the students' overall mood and their gain in knowledge. However, as changes would have to be anticipated when shifting to mandatory use, users' perceptions should be constantly evaluated.

Blended learning approach improves teaching in a problem-based learning environment in orthopedics - a pilot study.

BACKGROUND: While e-learning is enjoying increasing popularity as adjunct in modern teaching, studies on this topic should shift from mere evaluation of students' satisfaction towards assessing its benefits on enhancement of knowledge and skills. This pilot study aimed to detect the teaching effects of a blended learning program on students of orthopedics and traumatology in the context of a problem-based learning environment. METHODS: The project NESTOR (network for students in traumatology and orthopedics) was offered to students in a problem-based learning course. Participants completed written tests before and directly after the course, followed by a final written test and an objective structured clinical examination (OSCE) as well as an evaluation questionnaire at the end of the semester. Results were compared within the group of NESTOR users and non-users and between these two groups. RESULTS: Participants (n = 53) rated their experiences very positively. An enhancement in knowledge was found directly after the course and at the final written test for both groups (p < 0.001). NESTOR users scored higher than non-users in the post-tests, while the OSCE revealed no differences between the groups. CONCLUSIONS: This pilot study showed a positive effect of the blended learning approach on knowledge enhancement and satisfaction of participating students. However, it will be an aim for the future to further explore the chances of this approach and internet-based technologies for possibilities to improve also practical examination skills.

Noninvasive monitoring of training induced muscle adaptation with 31P-MRS: fibre type shifts correlate with metabolic changes.

PURPOSE: To evaluate training induced metabolic changes noninvasively with (31)P magnetic resonance spectroscopy ((31)P-MRS) for measuring muscle fibre type adaptation. METHODS: Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks). Prior to and following each training period, needle biopsies and (31)P-MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[P(i)], [PCr]/[ßATP] and [PCr + P(i)]/[ßATP]). The correlation between the changes of the (31)P-MRS parameters during training and the resulting changes in fibre composition were also analysed. RESULTS: We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[P(i)]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[P(i)] (r = 0.70, P < 0.01) or [PCr]/[ßATP] (r = 0.69, P < 0.01); the correlations between its changes (delta) and the fibre-shift were significant as well (delta[PCr]/[P(i)] r = 0.66, delta[PCr]/[ßATP] r = 0.55, P < 0.01). CONCLUSION: Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore (31)P-MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.

Parameters influencing the outcome after total disc replacement at the lumbosacral junction. Part 2: distraction and posterior translation lead to clinical failure after a mean follow-up of 5 years.

PURPOSE: The aim of the second part of the study was to investigate the influence of parameters that lead to increased facet joint contact or capsule tensile forces (disc height, lordosis, and sagittal misalignment) on the clinical outcome after total disc replacement (TDR) at the lumbosacral junction. METHODS: A total of 40 patients of a prospective cohort study who received TDR because of degenerative disc disease or osteochondrosis L5/S1 were invited to an additional follow-up for clinical (ODI and VAS for overall, back, and leg pain) and radiographic analysis (a change in disc height, lordosis, or sagittal vertebral misalignment compared with the preoperative state). Based on the final ODI, patients were retrospectively distributed into groups N (normal: <25 %) or F (failure ≥ 25 %) for radiographic parameter comparison. A correlation analysis was performed between the clinical and radiological results. RESULTS: A total of 34 patients were available at a mean follow-up of 59.5 months. Both groups (N = 24; F = 10 patients) presented a significant improvement in overall pain, back pain, and ODI over time. At the final follow-up, higher clinical scores correlated with a larger disc height, increased lordosis, and posterior translation of the superior vertebra, which was also reflected by significant differences in these parameters in the group comparison. CONCLUSIONS: Parameters associated with increased facet joint capsule tensile forces lead to an inferior clinical outcome at mid-term follow-up. When performing TDR, we therefore suggest avoiding iatrogenic posterior translation and overdistraction (and consecutive lordosis).

Can discoblock replace discography for identifying painful degenerated discs?

OBJECTIVES: The aim of the present study was to intra-individually compare provocative discography and discoblock (disc analgesia) of idiopathic degenerated discs (IDD) results to each other, to clinical parameters, and to MRI findings. By this the value of both diagnostic features should be critically reevaluated. METHODS: 31 intervertebral IDD (Pfirrmann III°-IV°) of 26 patients were analyzed for surgery decision making by combined discoblock/discography procedure in an open MRI at 1T. A correlation analysis was performed between the Dallas Discogram Scale, pain discrimination score (PDS: concordant/discordant/no pain), positive discoblock (Numerical Rating Scale [NRS] reduction by ≥ 3, 60 min after intervention), presence of Modic changes or high intensity zones (HIZ), patient sex and age, intervention level, injection pressure and discography endpoint analysis (pain/pressure/anatomic/volume). RESULTS: Concordant pain could be evoked in 35% of the IDDs whereas discoblock was positive in 64%. Patients' age, sex, Dallas I, Dallas II, and Pfirrmann scores, as well as the presence of HIZ did not correlate to PDS or discoblock results. Discoblock correlated positively to concordant pain. Further positive correlation was found between PDS and intervention level/pressure, between discoblock and Modic changes/discography endpoint as well as between HIZ and discography endpoint. CONCLUSIONS: We suggest discoblock to be an additional tool for surgery decision making in patients with IDD because it correlates to concordant pain evoked by provocative discography as well as to presence of Modic changes. Additionally, assessment of a release instead of provocation of pain can be of advantage.

Sequestrectomy with additional transpedicular dynamic stabilization for the treatment of lumbar disc herniation: no clinical benefit after 10 years follow-up.

STUDY DESIGN: Single-center prospective study. OBJECTIVE: Clinical and radiological long-term evaluation of the effects of transpedicular dynamic stabilization after sequestrectomy. SUMMARY OF BACKGROUND DATA: Short- and mid-term investigations have shown that additional dynamic stabilization is appropriate to prevent progression of initial segment degeneration after sequestrectomy and associated with superior clinical outcome compared with sequestrectomy alone. Long-term data are missing. METHODS: Eighty-four patients with symptomatic disc herniation and initial osteochondrosis (Modic = I°) of the lumbar spine underwent sequestrectomy. Additional dynamic stabilization was performed in 35 subjects (group D); the remaining 49 subjects were treated with sequestrectomy alone (group S). Clinical (Oswestry Low Back Pain Disability Questionnaire, Version 2.0; visual analogue scale) and radiological (plain and extension-flexion radiographs and magnetic resonance images) parameters were collected preoperatively, at 3 months postoperatively, as well as at a mean follow-up of 2.8 and 10.2 years. RESULTS: Twenty-nine of 35 (83%, group D) and 38 of 49 (78%, group S) patients were available at the final follow-up. Reoperation rate in group D was 34% (10/29) due to implant failures or progression of degeneration at the index or the adjacent segments. In group S, 5 of 38 (13%) underwent further operation because of a reprolapse or progression of degeneration of the index level. In the remaining patients, clinical scores (Oswestry Low Back Pain Disability Questionnaire, Version 2.0; and visual analogue scale) improved significantly, with similar results in both groups at the final follow-up. The rate of progression of disc degeneration was lower when the patients were also dynamically stabilized than sequestrectomy alone, but the rate of adjacent segment degeneration superior to the operated segment was significantly higher in group D. CONCLUSION: Additional dynamic stabilization does not lead to a clinical benefit in patients with symptomatic disc herniation and initial segment degeneration compared with sequestrectomy alone after a long-term follow-up. Because of this and the high rate of necessary reoperations, we do not recommend this surgical strategy for this indication. LEVEL OF EVIDENCE: 4.

Which radiographic parameters are linked to failure of a dynamic spinal implant?

BACKGROUND: Knowledge about factors leading to failure of posterior dynamic stabilization implants is essential to design future implants and establish surgical indications. Therefore, we analyzed an implant for single-level or hybrid configuration (adjacent to spondylodesis), which was recalled due to high failure rates. QUESTIONS/PURPOSES: We asked: (1) Were postoperative radiographic changes linked to implant failure? (2) Were radiographic parameters different between the two configurations? And (3) was implant failure related to inferior clinical scores? METHODS: The implant was used in 18 patients with lumbar single-level spinal stenosis or with (recurrent) disc herniation and concurrent degenerative disc disease and in 22 patients with an initially degenerated segment adjacent and superior to a fusion site. We prospectively obtained preoperative and postoperative (immediate, 6-, 12- and 24-month) clinical and radiographic evaluations; 37 of the 40 patients completed the 24-month followup. Using plain and extension-flexion radiographs, we compared implant failure rates and their association with postoperative implant translation, anterior and posterior disc height, and ROM for each configuration and between configurations. We assessed associations between clinical scores (VAS pain scores for back and leg, Oswestry Disability Index) and implant failure. RESULTS: Implant failure occurred in 10 of the 37 implants and corresponded to greater posterior disc height (single-level only) and implant translation. Adjacent-segment ROM increases and posterior disc height decreases over time were greater with the hybrid configuration. Implant failure rate related to higher Oswestry Disability Index (single-level only) and higher back pain scores. CONCLUSIONS: Implant translation is associated with failure likely due to insufficient resistance to shear forces. Load transfer may cause progressive degeneration in the dynamic and adjacent segments, especially in the hybrid configuration.

Stand-alone anterior versus anteroposterior lumbar interbody single-level fusion after a mean follow-up of 41 months.

STUDY DESIGN: Prospective cohort study comparing evaluations of single-level anterior lumbar interbody fusion (ALIF) versus anteroposterior lumbar fusion (APLF). OBJECTIVE: To clinically and radiologically compare the outcome after angle-stable, locked, stand-alone ALIF with that obtained after APLF, in cases with degenerative disc disease (DDD). SUMMARY OF BACKGROUND DATA: Fusion rates have been reported to be highest after interbody fusion with transpedicular fixation. However, transpedicular fixation is linked to significant damage of the paravertebral muscles, to screw displacement-related neurological and vascular complications, and to an increased rate of adjacent segment degeneration. When performed as a stand-alone procedure, the disadvantages of transpedicular fixation can be completely avoided by ALIF. METHODS: Eighty patients with chronic low-back pain due to a single-level DDD (Modic ≥2) and facet joint arthritis (Fujiwara ≥3) were enrolled in this study. Forty patients received an anteroposterior fusion (ALIF with transpedicular fixation: APLF group) and 40 patients (ALIF group) were treated with a stand-alone ALIF using the Synfix-LR device. At 7 days, 3, 6, 12, and 24 months, and at a mean follow-up of 41 months, patients were clinically (visual analog scale, Oswestry Low Back Pain Disability Index, satisfaction) and radiologically (x-ray, and at 12 months, thin-slice computed tomography) compared. RESULTS: Blood loss and duration of surgery were significantly lower in the ALIF group (P<0.001). Visual analog scale and Oswestry Low Back Pain Disability Index improved significantly over time (analysis of variance, P<0.001) in both groups, but both scores were significantly better in ALIF group (analysis of variance, P<0.001). Patients' satisfaction consistently ranked higher in the ALIF group (P=0.042 at 12 mo). No significant difference was found in the fusion rate throughout the study. CONCLUSIONS: Stand-alone ALIF leads to better clinical results than APLF, without differences in fusion rates after 41 months. Therefore, when a posterior approach is not needed for decompression or reposition, we suggest performing a stand-alone ALIF in cases with single-level DDD.

Dynamic stabilization adjacent to single-level fusion: part I. Biomechanical effects on lumbar spinal motion.

Progression of superior adjacent segment degeneration (PASD) could possibly be avoided by dynamic stabilization of an initially degenerated adjacent segment (AS). The current study evaluates ex vivo the biomechanics of a circumferential fixation connected to posterior dynamic stabilization at the AS. 6 human cadaver spines (L2-S1) were stabilized stepwise through the following conditions for comparison: intact spine (ISP), single-level fixation L5-S1 (SLF), SLF + dynamic AS fixation L4-L5 (DFT), and two-level fixation L4-S1 (TLF). For each condition, the moments required to reach the range of motion (ROM) of the intact whole spine segment under ±10 Nm (WSP10) were compared for all major planes of motion within L2-S1. The ROM at segments L2/3, L3/4, and L4/5 when WSP10 was applied were also compared for each condition. The moments needed to maintain WSP10 increased with each stage of stabilization, from ISP to SLF to DFT to TLF (p < 0.001), in all planes of motion within L2-S1. The ROM increased in the same order at L3/4 (extension, flexion, and lateral bending) and L2/3 (all except right axial rotation, left lateral bending) during WSP10 application with 300 N axial preload (p < 0.005 in ANOVA). At L4/5, while applying WSP10, all planes of motion were affected by stepwise stabilization (p < 0.001): ROM increased from ISP to SLF and decreased from SLF to DFT to TLF (partially p < 0.05). The moments required to reach WSP10 increase dependent on the number of fixated levels and the fixation stiffness of the implants used. Additional fixation shifts motion to the superior segment, according to fixation stiffness. Therefore, dynamic instrumentation cannot be recommended if prevention of hyper-mobility in the adjacent levels is the main target.

Dynamic stabilization adjacent to single-level fusion: part II. No clinical benefit for asymptomatic, initially degenerated adjacent segments after 6 years follow-up.

Progression of degeneration is often described in patients with initially degenerated segment adjacent to fusion (iASD) at the time of surgery. The aim of the present study was to compare dynamic fixation of a clinically asymptomatic iASD, with circumferential lumbar fusion alone. 60 patients with symptomatic degeneration of L5/S1 or L4/L5 (Modic ≥ 2°) and asymptomatic iASD (Modic = 1°, confirmed by discography) were divided into two groups. 30 patients were treated with circumferential single-level fusion (SLF). In dynamic fixation transition (DFT) patients, additional posterior dynamic fixation of iASD was performed. Preoperatively, at 12 months, and at a mean follow-up of 76.4 (60-91) months, radiological (MRI, X-ray) and clinical (ODI, VAS, satisfaction) evaluations assessed fusion, progression of adjacent segment degeneration (PASD), radiologically adverse events, functional outcome, and pain. At final follow-up, two non-fusions were observed in both groups. 6 SLF patients and 1 DFT patient presented a PASD. In two DFT patients, a PASD occurred in the segment superior to the dynamic fixation, and in one DFT patient, a fusion of the dynamically fixated segment was observed. 4 DFT patients presented radiological implant failure. While no differences in clinical scores were observed between groups, improvement from pre-operative conditions was significant (all p < 0.001). Clinical scores were equal in patients with PASD and/or radiologically adverse events. We do not recommend dynamically fixating the adjacent segment in patients with clinically asymptomatic iASD. The lower number of PASD with dynamic fixation was accompanied by a high number of implant failures and a shift of PASD to the superior segment.