Stepwise reduction of bone mineral density increases the risk of cage subsidence in oblique lumbar interbody fusion patients biomechanically: an in-silico study.

BACKGROUND: Cage subsidence causes poor prognoses in patients treated by oblique lumbar interbody fusion (OLIF). Deterioration of the biomechanical environment initially triggers cage subsidence, and patients with low bone mineral density (BMD) suffer a higher risk of cage subsidence. However, whether low BMD increases the risk of cage subsidence by deteriorating the local biomechanical environment has not been clearly identified. METHODS: OLIF without additional fixation (stand-alone, S-A) and with different additional fixation devices (AFDs), including anterolateral single rod screws (ALSRs) and bilateral pedicle screws (BPSs) fixation, was simulated in the L4-L5 segment of a well-validated finite element model. The biomechanical effects of different BMDs were investigated by adjusting the material properties of bony structures. Biomechanical indicators related to cage subsidence were computed and recorded under different directional moments. RESULTS: Overall, low BMD triggers stress concentration in surgical segment, the highest equivalent stress can be observed in osteoporosis models under most loading conditions. Compared with the flexion-extension loading condition, this variation tendency was more pronounced under bending and rotation loading conditions. In addition, AFDs obviously reduced the stress concentration on both bony endplates and the OLIF cage, and the maximum stress on ALSRs was evidently higher than that on BPSs under almost all loading conditions. CONCLUSIONS: Stepwise reduction of BMD increases the risk of a poor local biomechanical environment in OLIF patients, and regular anti-osteoporosis therapy should be considered an effective method to biomechanically optimize the prognosis of OLIF patients.

The Mismatch Between Bony Endplates and Grafted Bone Increases Screw Loosening Risk for OLIF Patients With ALSR Fixation Biomechanically.

The mismatch between bony endplates (BEPs) and grafted bone (GB) triggers several complications biomechanically. However, no published study has identified whether this factor increases the risk of screw loosening by deteriorating the local stress levels. This study aimed to illustrate the biomechanical effects of the mismatch between BEP and GB and the related risk of screw loosening. In this study, radiographic and demographic data of 56 patients treated by single segment oblique lumbar interbody fusion (OLIF) with anterior lateral single rod (ALSR) fixation were collected retrospectively, and the match sufficiency between BEP and GB was measured and presented as the grafted bony occupancy rate (GBOR). Data in patients with and without screw loosening were compared; regression analyses identified independent risk factors. OLIF with different GBORs was simulated in a previously constructed and validated lumbosacral model, and biomechanical indicators related to screw loosening were computed in surgical models. The radiographic review and numerical simulations showed that the coronal plane's GBOR was significantly lower in screw loosening patients both in the cranial and caudal vertebral bodies; the decrease in the coronal plane's GBOR has been proven to be an independent risk factor for screw loosening. In addition, numerical mechanical simulations showed that the poor match between BEP and GB will lead to stress concentration on both screws and bone-screw interfaces. Therefore, we can conclude that the mismatch between the BEP and GB will increase the risk of screw loosening by deteriorating local stress levels, and the increase in the GBOR by modifying the OLIF cage's design may be an effective method to optimize the patient's prognosis.

Deterioration of the fixation segment's stress distribution and the strength reduction of screw holding position together cause screw loosening in ALSR fixed OLIF patients with poor BMD.

The vertebral body's Hounsfield unit (HU) value can credibly reflect patients' bone mineral density (BMD). Given that poor bone-screw integration initially triggers screw loosening and regional differences in BMD and strength in the vertebral body exist, HU in screw holding planes should better predict screw loosening. According to the stress shielding effect, the stress distribution changes in the fixation segment with BMD reduction should be related to screw loosening, but this has not been identified. We retrospectively collected the radiographic and demographic data of 56 patients treated by single-level oblique lumbar interbody fusion (OLIF) with anterior lateral single rod (ALSR) screw fixation. BMD was identified by measuring HU values in vertebral bodies and screw holding planes. Regression analyses identified independent risk factors for cranial and caudal screw loosening separately. Meanwhile, OLIF with ALSR fixation was numerically simulated; the elastic modulus of bony structures was adjusted to simulate different grades of BMD reduction. Stress distribution changes were judged by computing stress distribution in screws, bone-screw interfaces, and cancellous bones in the fixation segment. The results showed that HU reduction in vertebral bodies and screw holding planes were independent risk factors for screw loosening. The predictive performance of screw holding plane HU is better than the mean HU of vertebral bodies. Cranial screws suffer a higher risk of screw loosening, but HU was not significantly different between cranial and caudal sides. The poor BMD led to stress concentrations on both the screw and bone-screw interfaces. Biomechanical deterioration was more severe in the cranial screws than in the caudal screws. Additionally, lower stress can also be observed in fixation segments' cancellous bone. Therefore, a higher proportion of ALSR load transmission triggers stress concentration on the screw and bone-screw interfaces in patients with poor BMD. This, together with decreased bony strength in the screw holding position, contributes to screw loosening in osteoporotic patients biomechanically. The trajectory optimization of ALSR screws based on preoperative HU measurement and regular anti-osteoporosis therapy may effectively reduce the risk of screw loosening.

Adductor canal block versus femoral nerve block for total knee arthroplasty: a meta-analysis of randomized controlled trials.

Femoral nerve blocks (FNB) can provide effective pain relief but result in quadriceps weakness with increased risk of falls following total knee arthroplasty (TKA). Adductor canal block (ACB) is a relatively new alternative providing pure sensory blockade with minimal effect on quadriceps strength. The meta-analysis was designed to evaluate whether ACB exhibited better outcomes with respect to quadriceps strength, pain control, ambulation ability, and complications. PubMed, Embase, Web of Science, Wan Fang, China National Knowledge Internet (CNKI) and the Cochrane Database were searched for RCTs comparing ACB with FNB after TKAs. Of 309 citations identified by our search strategy, 12 RCTs met the inclusion criteria. Compared to FNB, quadriceps maximum voluntary isometric contraction (MVIC) was significantly higher for ACB, which was consistent with the results regarding quadriceps strength assessed with manual muscle strength scale. Moreover, ACB had significantly higher risk of falling versus FNB. At any follow-up time, ACB was not inferior to FNB regarding pain control or opioid consumption, and showed better range of motion in comparison with FNB. ACB is superior to the FNB regarding sparing of quadriceps strength and faster knee function recovery. It provides pain relief and opioid consumption comparable to FNB and is associated with decreased risk of falls.

Complications of Lumbar Disc Herniation Following Full-endoscopic Interlaminar Lumbar Discectomy: A Large, Single-Center, Retrospective Study.

BACKGROUND: The new surgical procedure of full-endoscopic interlaminar lumbar discectomy (FILD) has achieved favorable effects in the treatment of lumbar disc herniation (LDH). Along with the wide range of applications of FILD, a series of complications related to the operation has gradually emerged. OBJECTIVE: To describe the types, incidences, and characteristics of complications following FILD and to explore preventative and treatment measures. STUDY DESIGN: Retrospective, observational study. SETTING: A spine center affiliated with a large general hospital. METHOD: In total, 479 patients with LDH underwent FILDs that were performed by a single experienced spine surgeon between January 2010 and April 2013. Data concerning the complications were recorded. RESULTS: All 479 cases successfully underwent the procedure. A total of 482 procedures were completed. The mean follow-up time was 44.3 months with a range of 24 to 60 months. The average patient age was 47.8 years with a range of 16 to 76 years. Twenty-nine (6.0%) related complications emerged, including 3 cases (0.6%) of incomplete decompression in which the symptoms gradually decreased following 3 - 6 weeks of conservative treatment, 2 cases (0.4%) of nerve root injury in which the patients recovered well following 1 - 3 months of neurotrophic drug and functional exercise treatment, 15 cases (3.1%) of paresthesia that gradually improved following 1 - 8 weeks of rehabilitation exercises and treatment with mecobalamin and pregabalin, and 9 cases of recurrent herniation (1.9%). The latter condition was controlled in 4 cases with a conservative method, and 5 of these cases underwent reoperations that included 3 traditional open surgeries and 2 FILDs. Furthermore, the complication rate for the first 100 cases was 18%. This rate decreased to 2.9% for cases 101 - 479. The incidence of L4-5 herniation (8.2%) was significantly greater than that of L5-S1 (4.5%). LIMITATIONS: This is a retrospective study, and some bias exists due to the single-center study design. CONCLUSION: FILD is a surgical approach that has a low complication rate. Incomplete decompression, nerve root injury, paresthesia, and recurrent herniation were observed in our study. Some effective measures can prevent and reduce the incidence of the complications including strict indications for surgery, a thorough action plan, and a high level of surgical skill. Key words: Complication, lumbar disc herniation, lumbar discectomy, endoscopic, inter-laminar discectomy, minimally invasive spine surgery.

Closed Suction Drainage Is Not Associated with Faster Recovery after Total Knee Arthroplasty: A Prospective Randomized Controlled Study of 80 Patients.

OBJECTIVE: To evaluate whether closed suction drainage (CSD) is associated with early recovery of knee function in patients undergoing total knee arthroplasty (TKA). METHODS: Between January 2015 and September 2015, 80 consecutive patients were prospectively randomized into two groups: a CSD group (40 cases; average age, 66.9 ± 8.6 years; male, 8; female, 32) and a non-CSD group (40 cases; average age, 66.8 ± 10.1 years; male, 9; female, 31). Local inflammation outcomes (assessed by a visual analog scale [VAS], swelling and skin temperature), calculated total blood loss (CBL), hidden blood loss (HBL), blood transfusion requirements and hemoglobin concentrations were recorded. Hospital for Special Surgery (HSS) knee scores, range of motion (ROM), limb swelling, tension vesicles, ecchymosis, time to regaining straight leg raising and duration of hospital stay were documented. All surgeries were performed by the same surgeon and followed up for 3 months. RESULTS: The peri-wound skin temperature and knee VAS pain scores were lower in the non-CSD group. Patients in the non-CSD group had significantly better knee ROM (P = 0.028). The time to regaining active straight leg raising was significantly shorter in the non-CSD groupN than in the CSD group (P = 0.014). In addition, patients in the non-CSD group had a shorter length of hospital stay (P = 0.004) than those in the CSD group, indicating earlier recovery of knee function. HBL was significantly less in the CSD group than the non-CSD group (P = 0.006) on postoperative day (POD) 5. However, CBL did not differ significantly between the two groups on POD5. There were no significant differences between two groups in all other assessed variables. CONCLUSION: In this randomized study, primary TKA without CSD was associated with faster recovery related to less local inflammation and better early knee function. Furthermore, use of a drain had no significant advantage with respect to other outcome measures and may have increased costs. Based on these data, CSD after primary TKA is not routinely indicated.

Prognostic role of the lymph node ratio in node positive colorectal cancer: a meta-analysis.

The lymph node ratio (LNR) (i.e. the number of metastatic lymph nodes divided by the number of totally resected lymph nodes) has recently emerged as an important prognostic factor in colorectal cancer (CRC). However, the tumor node metastasis (TNM) staging system for colorectal cancer does not consider it as a prognostic parameter. Therefore, we conducted a meta-analysis to evaluate the prognostic role of the LNR in node positive CRC. A systematic search was performed in PubMed, Embase and the Cochrane Library for relevant studies up to November 2015. As a result, a total of 75,838 node positive patients in 33 studies were included in this meta-analysis. Higher LNR was significantly associated with shorter overall survival (OS) (HR = 1.91; 95% CI 1.71-2.14; P = 0.0000) and disease free survival (DFS) (HR = 2.75; 95% CI: 2.14-3.53; P = 0.0000). Subgroup analysis showed similar results. Based on these results, LNR was an independent predictor of survival in colorectal cancer patients and should be considered as a parameter in future oncologic staging systems.