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BackgroundThis study aimed to determine whether the accelerometer-based navigation (ABN) could improve the accuracy of restoring mechanical axis (MA), component positioning, and clinical outcomes compared to conventional (CON) total knee arthroplasty (TKA).MethodsA total of 301 consecutive patients (ABN: 27, CON: 274) were included. A 1:4 propensity score matching (PSM) was performed between the two groups according to preoperative demographic and clinical parameters. The postoperative MA, femoral coronal angle (FCA), femoral sagittal angle (FSA), tibial coronal angle (TCA) and tibial sagittal angle (TSA) were compared. Absolute deviations of aforementioned angles were calculated as the absolute value of difference between the exact and ideal value and defined as norms if within 3°, otherwise regarded as outliers. Additional clinical parameters, including the Knee Society knee and function scores (KSKS and KSFS) and range of motion (ROM), were assessed at final follow-up (FU) (mean FU was 21.88 and 21.56 months respectively for ABN and CON group). A secondary subgroup analysis and comparison on clinical outcomes were conducted between norms and outliers in different radiological parameters.ResultsA total of 98 patients/102 knees were analyzed after the PSM (ABN: 21 patients/24 knees, CON: 77 patients/78 knees). In the ABN group, the mean MA, FCA and TSA were significantly improved (p = 0.019, 0.006, p = 0.003, 0.021, 0.042, 0.013, respectively for MA, FCA, FSA, and TSA). The absolute deviations of FSA and TSA were also significantly lower in the ABN group (p = 0.020, 0.048, respectively). No significant differences were found in either mean value, absolute deviation or outlier ratio of TCA between two groups. On clinical outcomes, there were no significant differences between two groups, although KSKS, KSFS and ROM (p ConclusionsThe ABN could improve the accuracy and precision of mechanical alignment and component positioning without significant improvement of clinical outcomes. Further high quality studies with long term FU are warranted to comprehensively evaluate the value of the ABN.

Total knee arthroplasty (TKA) for patients with valgus deformity (> 10 degrees) is technically challenging and has produced variable clinical results in terms of deformity correction, instability, and overall outcomes. The lateral parapatellar approach (LPA) is an alternative to the traditional medial parapatellar approach with potential advantages of direct access for release of tight lateral ligamentous structures with preservation of the medial structures, optimized patellar tracking, preserved medial blood supply to the patella, and less use of constrained implants. We present a case series of a single institution's experience with use of a modified LPA using a Z-capsuloplasty for 35 primary TKA cases in 30 patients with osteoarthritis and Ranawat's type-II fixed valgus deformity with attenuation of medial soft tissues. The mean age of patients was 64.8 years (range: 42–78 years). Follow-up duration was a mean of 47.3 months (range: 3–130 months). The patients were assessed pre- and postoperatively using radiographic measurement of the anatomic femorotibial angle (FTA) and clinical measurement of range of motion (ROM) and the Chinese knee society score (KSS). Complications and reoperations were recorded. The mean coronal alignment was corrected from 20.4 degrees of valgus (range: 11.3–42 degrees) preoperatively to 7.0 degrees of valgus (range: 3.6–15.1 degrees) postoperatively. One case required use of a constrained condylar design implant. At a mean of 47.3 months, the mean Knee Society objective and functional scores improved to 91.8 ± 6.6 and 84.3 ± 18.2 points, respectively. Mean ROM was 94.9 degrees preoperatively and 105.7 degrees postoperatively. Three cases (8.6%) had postoperative complications, including transient common peroneal nerve palsy, hematoma, and deep infection. One patient underwent two-stage revision for infection. There were no cases of late instability. The modified LPA using a Z-capsuloplasty is a reproducible and effective surgical technique for performing TKA in the setting of osteoarthritis and severe valgus deformity.

We sought is to determine the mechanism of failure among primary total knee arthroplasties (TKAs) performed at a single high-volume institution by asking the following research questions: (1) What are the most common failure modes for modern TKA designs? and (2) What are the preoperative risk factors for failure following primary TKA?From May 2007 to December 2012, 18,065 primary TKAs performed on 16,083 patients at a single institution were recorded in a prospective total joint arthroplasty registry with a minimum of 5-year follow-up. We retrospectively reviewed patient charts to determine a cause of failure for primary TKAs. A cox proportional hazard model was used to determine the risk of revision surgery following primary TKA.The most common reasons for failure within 2 years after TKA were infection and stiffness. The multivariable regression identified the following preoperative risk factors for TKA failure: history of drug abuse (hazard ratio [HR] 4.68; P = 0.03), deformity/mechanical preoperative diagnosis (HR 3.52; P.01), having a constrained condylar knee implant over posterior-stabilized implant (HR 1.99; P.01), post-traumatic/trauma preoperative diagnosis (HR 1.78; P = .03), and younger age (HR 0.61; P.01) CONCLUSION: These findings add to the growing data that primary TKAs are no longer failing from polyethylene wear-related issues. This study identified preoperative risk factors for failure of primary TKAs, which may be useful information for developing strategies to improve outcomes following TKA.

Implant malalignment in primary TKA has been reported to increase stresses placed on the bearing surfaces of implant components. We used a longitudinally maintained registry coupled with an implant retrieval program to consider whether preoperative, postoperative, or prerevision malalignment was associated with increased risk of revision surgery after TKA. (1) What is the relative polyethylene damage on medial and lateral compartments of the tibial plateaus from revised TKAs? (2) Does coronal TKA alignment affect implant performance, such that TKAs aligned in varus are predisposed to experience increased polyethylene damage? (3) Does TKA alignment differ between postoperative and prerevision radiographs, and if so, what does this difference suggest about the mechanical contact load placed on a knee with a TKA? Between 2007 and 2012, we performed 18,065 primary TKAs at our institution. By March 2016, 178 of those TKAs (1%) were revised at our center at least 2 years after primary surgery at our institution. Eighteen of those TKAs were excluded from this analysis because the tibial insert was not explanted during revision surgery, and four more were excluded because the inserts were lost or returned to the patient before the study was initiated, leaving 156 retrieved polyethylene tibial inserts (in 153 patients) revised at greater than 2 years after the primary TKA for this retrospective study. Patients who underwent revision surgery elsewhere were not considered here, since this study depended on having retrieved components. Polyethylene damage modes of burnishing, pitting, scratching, delamination, surface deformation, abrasion, and third-body debris were subjectively graded on a scale of 0 to 3 to reflect the extent and severity of each damage mode. On preoperative, postoperative, and prerevision radiographs, overall alignment, femoral alignment, and tibial alignment in the coronal plane were measured according to the protocol recommended by the Knee Society. Knees with more overall varus alignment after TKA had increased total damage on the retrieved tibial inserts (Spearman’s rank correlation coefficients of −0.3 [95% CI, −0.4 to −0.1; p = 0.001]). We also found revised TKAs tended to drift back into greater varus before revision surgery, with a mean (SD) of 3.6° ± 4.0° valgus for postoperative alignment compared with 1.7° ± 6.4° prerevision (p = 0.04). Despite surgical efforts to achieve neutral mechanical alignment, remaining varus alignment places an increased contact load on the polyethylene articular surfaces. The drift toward further varus alignment postoperatively is consistent with the knee adduction moment remaining high after surgery. While we found a predisposition toward recurrence of the preoperative varus deformity, we did not find increased medial as opposed to lateral polyethylene damage, which may be explained by the curve-on-curve toroidal design of the articulating surfaces of the TKA implants in this study.

Tourniquets are still widely used in total knee arthroplasty (TKA), although they may be associated with several adverse effects. An observer-blinded, randomized, controlled trial was performed to evaluate the effects of tourniquet use in TKA. Fifty participants who underwent staged bilateral TKA were recruited for this study. The first-side TKA was randomly allocated to either long-duration tourniquet use or short-duration tourniquet use followed by a 3-month washout period and crossover to the other tourniquet strategy for the opposite-side TKA. Blood loss was monitored perioperatively. The operating time, allogeneic blood transfusion rate, thigh pain, knee pain, limb swelling, clinical outcome as measured by the Likert-type Western Ontario and McMaster University (WOMAC) score, straight leg raising and knee active range of motion (ROM) were also recorded. The long-duration tourniquet group exhibited reduced total blood loss [−99.1 ml, 95 % confidence interval (CI) −168.1 to −30.1, P = 0.0411] and intraoperative blood loss (−225.2 ml, 95 % CI −369.5 to −80.9, P = 0.0071) compared with the short-duration tourniquet group. However, there were greater postoperative blood loss (69.6 ml, 95 % CI 21.1 to 118.2, P = 0.0282) and hidden blood loss (52.8 ml, 95 % CI 10.5 to 95.1, P = 0.0332) in the long-duration tourniquet group. The short-duration tourniquet group showed better outcomes for thigh and knee pain, limb swelling, WOMAC score at 6-week follow-up, straight leg raising and knee ROM. Similar allogeneic blood transfusion rates were observed for both groups. Total and intraoperative blood losses were reduced with the long-duration tourniquet use, whereas the short-duration tourniquet use would reduce postoperative and hidden blood losses without increasing the allogeneic blood transfusion rate. In addition, short-duration tourniquet use would result in faster recovery and less pain during the early rehabilitation period following TKA. I.

Necrotizing enterocolitis (NEC) is a life-threatening condition that can occur in about 7% of pre-term infants, and approximately 20% to 30% of the cases will end in death. An overactive immune response is thought to be a primary instigator of many symptoms during NEC. Hence, we hypothesized that NEC patients might present impairment in regulatory T (Treg) cells that limited their capacity to contain the excessive inflammation-induced damage. To investigate this, peripheral blood mononuclear cells were collected from NEC and non-NEC infants with matching age and weight. Treg cells, identified as CD3+CD4+CD25+/hiFoxp3+ T cells, were present at significantly lower frequency in NEC infants than in non-NEC infants. We also observed that the frequency of IL‑17+ CD4+ T cells was significantly higher in NEC infants, while the frequencies of IL‑10+ and TGF‑β+ CD4+ T cells were significantly lower in NEC infants. The CD4+CD25+/hi Treg cells from NEC infants were capable of suppressing CD4+CD25− T conventional cell proliferation, but with significantly reduced potency than the CD4+CD25+/hi Treg cells from non-NEC infants. In addition, the CD4+CD25+/hi Treg cells from non-NEC infants, but not those from NEC infants, were capable of suppressing IL‑17 expression. Furthermore, the CD4+CD25+/hi Treg cells from NEC infants displayed reduced expression of CTLA‑4, LAG‑3, and Helios, compared to those from non-NEC infants. Overall, these results demonstrated that Treg cells from NEC infants displayed a multitude of functional impairments, and suggested that Treg cells might serve as a treatment target in NEC.

Necrotizing enterocolitis (NEC) is a potentially fatal disease that develops in the intestinal tract of newborn infants. An overactive immune system in the intestinal tract of NEC patients not only propagates inflammation and mediates tissue damage, but may also radiate the disease systemically and impose injury to distant organs. We previously identified impairment in the Treg compartment in NEC patients. Here, we hypothesized that monocytes, which could promote iTreg differentiation both in vitro and in vivo , were dysregulated in NEC infants. In age-, sex-, and weight-matched NEC infants and healthy control infants, the monocytes from PBMCs were investigated. Monocytes from NEC infants presented significantly higher TLR4 expression. With or without LPS stimulation, monocytes from NEC infants presented elevated TNF-α and IL-6 expression, together with reduced expression of TGF-β. When incubated with autologous CD4 + T cells, monocytes from NEC infants preferentially promoted the differentiation of RORγt-expressing Th17 cells, but not Foxp3-expressing Treg cells. However, using exogenous TGF-β and IL-10, the development of Foxp3 expression could be significantly elevated. Together, these results demonstrate that monocytes in NEC patients displayed a proinflammatory profile that might contribute to the production of proinflammatory cytokines and the suppression of Treg cells.

To acquire a better understanding of how individuals adapt to knee osteoarthritis (KOA) and assess the effect of TKA, 3D gait analysis was conducted 17 pre-TKA KOA patients, 10 post-TKA KOA patients and 12 age-matched control subjects. Principle component analysis was used to extract waveform characteristics. Improved function was observed after TKA, but the overall lower limb capacity of post-TKA patients at 4 month post-surgery was still far below that of the control subjects. Post-TKA patients were characterized by reduced knee flexion, delayed joint motion and more gentle moments and ground reaction curves compared to controls.

As one of the most frequently used grafts in anterior cruciate ligament (ACL) reconstruction, hamstring tendon (HT) grafts are prepared with different lengths and fixed by specific fixations in knee joints. However, there are incomplete studies to investigate both the joint kinematics and graft biomechanics in the ACL reconstructions with different HT graft lengths. In this paper, three different graft lengths (i.e., 30, 50, and 70 mm) were developed in the ACL reconstruction and analyzed using finite element method under two usual clinical test loads (i.e., 134 N anterior tibial drawer and pivot shift test load). The different mechanical properties of the corresponding fixations were also considered for each graft length. It was revealed that the change in HT graft length would cause different strain and stress results in the grafts, but did not greatly influence joint stabilities under the two clinical test loads. The graft reaction force at the femoral fixation was always greatly lower than that at the tibial fixation regardless of load and graft length. The comparison of stress and strain results also indicated that more graft tissues inside the femoral and tibial tunnels could decrease the stress and strain values at the femoral and tibial fixation sites, respectively.

The musculoskeletal ligament is a kind of multiscale composite material with collagen fibers embedded in a ground matrix. As the major constituent in ligaments to bear external loads, collagens are composed mainly of two collagen contents with different mechanical properties, i.e., types I and III collagen. The constitutive relation of ligaments plays a critical role in the stability and normal function of human joints. However, collagen types have not been distinguished in the previous constitutive relations. In this paper a constitutive relation for ligament tissues was modified based on the previous constitutive relation by considering the effects of collagen types. Both the collagen contents and the mechanical properties of sixteen ligament specimens from four cadaveric human knee joints were measured for determining their material coefficients in the constitutive relation. The mechanical behaviors of ligaments were obtained from both the uniaxial tensile and simple shear tests. A linear regression between joint kinematic results from in vitro and in silico experiments was made to validate the accuracy of this constitutive relation. The high correlation coefficient (R(2)=0.93) and significance (P

A Q- value of 4.046 ±0.102 MeV has been determined for the two protons transfer reaction 160Gd(18O, 20Ne) 158Sm at 98.95 MeV. This result yields a first experimental measured value of − 65.738 ± 0.102 MeV for the mass excess of 158Sm, the nucleus far from stability. The result is compared with current theoretical predictions.