The SNAP trial: a double blind multi-center randomized controlled trial of a silicon nitride versus a PEEK cage in transforaminal lumbar interbody fusion in patients with symptomatic degenerative lumbar disc disorders: study protocol.

BACKGROUND: Polyetheretherketone (PEEK) cages have been widely used in the treatment of lumbar degenerative disc disorders, and show good clinical results. Still, complications such as subsidence and migration of the cage are frequently seen. A lack of osteointegration and fibrous tissues surrounding PEEK cages are held responsible. Ceramic implants made of silicon nitride show better biocompatible and osteoconductive qualities, and therefore are expected to lower complication rates and allow for better fusion.Purpose of this study is to show that fusion with the silicon nitride cage produces non-inferior results in outcome of the Roland Morris Disability Questionnaire at all follow-up time points as compared to the same procedure with PEEK cages. METHODS/DESIGN: This study is designed as a double blind multi-center randomized controlled trial with repeated measures analysis. 100 patients (18-75 years) presenting with symptomatic lumbar degenerative disorders unresponsive to at least 6 months of conservative treatment are included. Patients will be randomly assigned to a PEEK cage or a silicon nitride cage, and will undergo a transforaminal lumbar interbody fusion with pedicle screw fixation. Primary outcome measure is the functional improvement measured by the Roland Morris Disability Questionnaire. Secondary outcome parameters are the VAS leg, VAS back, SF-36, Likert scale, neurological outcome and radiographic assessment of fusion. After 1 year the fusion rate will be measured by radiograms and CT. Follow-up will be continued for 2 years. Patients and clinical observers who will perform the follow-up visits will be blinded for type of cage used during follow-up. Analyses of radiograms and CT will be performed independently by two experienced radiologists. DISCUSSION: In this study a PEEK cage will be compared with a silicon nitride cage in the treatment of symptomatic degenerative lumbar disc disorders. To our knowledge, this is the first randomized controlled trial in which the silicon nitride cage is compared with the PEEK cage in patients with symptomatic degenerative lumbar disc disorders. TRIAL REGISTRATION: NCT01557829.

Comparison of polyetheretherketone versus silicon nitride intervertebral spinal spacers in a caprine model.

Polyetheretherketone (PEEK) is commonly used as a spinal spacer for intervertebral fusion surgery. Unfortunately, PEEK is bioinert and does not effectively osseointegrate into living bone. In contrast, comparable spacers made of silicon nitride (Si3 N4 ) possess a surface nanostructure and chemistry that encourage appositional bone healing. This observational study was designed to compare the outcomes of these two biomaterials when implanted as spacers in an adult caprine model. Lumbar interbody fusion surgeries were performed at two adjacent levels in eight adult goats using implants of PEEK and Si3 N4 . At six-months after surgery, the operative and adjacent spinal segments were extracted and measured for bone fusion, bone volume, bone-implant contact (BIC) and soft-tissue implant contact (SIC) ratios, and biodynamic stability. The null hypothesis was that no differences in these parameters would be apparent between the two groups. Fusion was observed in seven of eight implants in each group with greater bone formation in the Si3 N4 group (52.6%) versus PEEK (27.9%; p = 0.2). There were no significant differences in BIC ratios between PEEK and Si3 N4 , and the biodynamic stability of the two groups was also comparable. The results suggest that Si3 N4 spacers are not inferior to PEEK and they may be more effective in promoting arthrodesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 688-699, 2019.

Temporary Segmental Distraction in a Dog with Degenerative Lumbosacral Stenosis.

OBJECTIVES: Degenerative lumbosacral stenosis (DLSS) is characterized by intervertebral disc degeneration and causes lower back pain in dogs. Temporary distraction in rabbit models with induced intervertebral disc degeneration showed signs of intervertebral disc repair. In the present study, we assessed safety and efficacy of temporary segmental distraction in a dog with clinical signs of DLSS. METHODS: Distraction of the lumbosacral junction by pedicle screw-rod fixation was applied in a 5-year-old Greyhound with DLSS and evaluated by radiography, magnetic resonance imaging, and force plate analysis before and after distraction. RESULTS: Safe distraction of the lumbosacral junction was demonstrated, with improvement of clinical signs after removal of the distraction device. Signal intensity of the intervertebral disc showed no changes over time. T2 value was highest directly after removal of the distraction device but decreased by 10% of the preoperative value at 9 months of follow-up. Disc height decreased (8%) immediately after removal of the distraction device, but recovered to the initial value. A decrease in the pelvic/thoracic propulsive force during pedicle screw-rod fixation and distraction was demonstrated, which slowly increased by 4% compared with the initial value. CLINICAL SIGNIFICANCE: Temporary pedicle screw-rod fixation in combination with distraction in a dog with DLSS was safe, improved clinical signs and retained disc height at 9 months of follow-up.

After total knee arthroplasty, many people are not active enough to maintain their health and fitness: an observational study.

QUESTIONS: What proportion of people after total knee arthroplasty adheres to the physical activity regimen recommended for maintenance of health (moderate intensity physical activity for at least 30min on 5 days/week)? What proportion adheres to the activity regimen recommended to improve fitness (vigorous intensity physical activity for at least 20min on 3 days/week)? What factors are associated with adherence to these recommendations? DESIGN: An observational study. PARTICIPANTS: 830 adults who underwent a total knee arthroplasty between 2002 and 2006 at University Medical Center Gronigen or Martini Hospital Gronigen, the Netherlands. OUTCOME MEASURES: The Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH) was used to measure the physical activity behaviour of the participants. These data were analysed as adherence to each recommendation. RESULTS: The health recommendation was adhered to by 51% of the participants. The fitness recommendation was adhered to by 53% of participants. Almost half (46%) of the participants fulfilled both recommendations, and 42% did not fulfil either recommendation. Males and more educated participants had higher odds of meeting the health, fitness, and both recommendations. Respondents living with family had higher odds of meeting the fitness recommendation. CONCLUSION: After total knee arthroplasty, 42% of people are not active enough to maintain their health and fitness. Physiotherapists should encourage people with a total knee arthroplasty to undertake the recommended exercise regimens to maintain health and fitness, with particular attention to those people with characteristics known to be associated with poor adherence to the recommendations.

Habitual physical activity after total knee replacement.

BACKGROUND: Previous studies on physical activity after total knee arthroplasty (TKA) concentrated mainly on a return to sports activities. OBJECTIVE: The objectives of this study were to determine the habitual physical activity behavior of people who had undergone TKA (TKA group) 1 to 5 years after surgery and to examine to what extent they adhered to international guidelines for health-enhancing physical activity. Additional aims were to compare younger (<65 years old) and older (≥ 65 years old) people as well as men and women in the TKA group and to compare the results for the TKA group with those for a sex- and age-matched normative population (normative group). DESIGN: This investigation was a cohort study. METHODS: All people who had a primary TKA at 1 of 2 participating hospitals between 2002 and 2006 were sent the Short Questionnaire to Assess Health-Enhancing Physical Activity at least 1 year after surgery. RESULTS: The TKA group spent, on average, 1,347 minutes per week on physical activity, most of which was light-intensity activity (780 minutes per week). Participants younger than 65 years of age spent significantly more time on physical activity than participants 65 years of age or older. There was no significant difference between male and female participants. Compared with the sex- and age-matched normative group, the TKA group spent significantly less time on the total amount of physical activity per week and met the guidelines for health-enhancing physical activity less often (55% versus 64%). LIMITATIONS: A self-administered questionnaire was used to assess habitual physical activity, and presurgery data on physical activity were not available. CONCLUSIONS: Almost half of the TKA group did not meet the health-enhancing physical activity guidelines, and the TKA group was not as physically active as the normative group. People who have undergone TKA should be encouraged to be more physically active.