Narrow Results

The energies of cosmic rays, fully ionized charged nuclei, extend over a wide range up to 10²⁰ eV. A particularly interesting energy region spans from 10¹⁴ to 10¹⁸ eV, where the all-particle energy spectrum exhibits two interesting structures, the "knee" and the "second knee". An explanation of these features is thought to be an important step in understanding the origin of the high-energy particles. Recent results of air shower experiments in this region are discussed. Special attention is drawn to explain the principle of air shower measurements — a simple Heitler model of (hadronic) air showers is developed.

An overview is given on results from direct and indirect measurements of galactic cosmic rays. Their implications on the contemporary understanding of the origin of cosmic rays and the knee in their energy spectrum are discussed.

We summarize the main results reported by EAS-TOP in the study of cosmic rays in the energy range 10¹² – 10¹⁶ eV (from the direct measurements up to above the "knee"), i.e. the region which is generally considered to represent the high energy galactic radiation.

The origin of the knee in the energy spectrum of cosmic rays is one of the central questions of high-energy astrophysics. One possible explanation is the energy dependent leakage of nuclei from the Galaxy due to their propagation. The latter is investigated in a combined method using numerical calculations of trajectories and the diffusion approximation. The life time of cosmic rays in the Galaxy and the corresponding pathlength are presented. The resulting energy spectra as observed at Earth are discussed and compared to experimental data.

Knee formation in the EAS size spectrum as a possible result of some portion of EAS's energy carried away by some missing EAS component is discussed. To explain the absence of the bump in calculated EAS size spectrum for the standard EAS development in the present day experiments, the model of "catastrophic" EAS development was proposed. The hypothesis that all the energy lost for the further shower development E_LT finally passes into neutrino (¾E_LT) and muons (¼E_LT) is shown to be practically excluded by present experimental data.

A rare giant loose body in the knee joint and the treatment carried out were reported. Two loose bodies sized 5.5 and 1.5 cm were extracted from the knee of a patient who suffered from pain and knee motion restricted chronically. The histopathological evaluation revealed normal bone, hyaline cartilaginous tissue, and partly fibrocartilaginous tissue. These loose bodies suggested that they were separated in small pieces from the femoral condyles and were nourished by the synovial fluid. Over time, they adhered to each other in the knee joint.

This study was performed to assess the effect of intra-articularly-injected 3.0% povidone-iodine solution and 2% H₂O₂ on the joint cartilage. Ninety 12-week-old Spraque Dawley rats, weighing 250 g on average, were used; ten were used as controls without any treatment, and 80 were equally divided into four groups for the experiment. In group I, 0.05 ml of normal saline was injected twice into the right knee joints at intervals of one week each, and a running load over a treadmill was added until the animals were sacrificed. In group II, 0.05 ml of 2% H₂O₂ was injected twice into the right knees over the same interval. In group III, 0.05 ml of 2% H₂O₂ was injected twice into the right knees over the same weekly interval, and a running load was added until the knees were sacrificed. In group IV, 0.05 ml of 3.0% povidone-iodine was injected twice into the right knees at one week intervals and a running load was also added until their sacrifice. In each experimental group, five rats were sacrificed at two, four, six and eight weeks after the first intra-articular injection, respectively, and the medial femoral condyles of the joints were taken for histological study of the articular cartilage. After saline injection and running load were applied, stage-I cartilage degeneration was observed at eight weeks after the first saline injection. After H₂O₂ injection only, stage-I cartilage degeneration was observed at four and six weeks, and the changes progressed to Wagenhäuser stage-II degeneration at eight weeks. After H₂O₂ injection and running load were applied, there were no histologic changes by two weeks, but stage-II cartilage degeneration was induced as early as six weeks after the first H₂O₂ injection. After povidone-iodine injection and running load were applied, stage-I cartilage degeration was observed at two weeks, and was maintained up to six weeks. Stage-II degeneration was observed at eight weeks. The matriceal proteoglycan contents was relatively high in comparison with the other groups. Safranin-O stain reduction was observed in groups I, II, III and IV before the histological changes were being observed. From the results, it was found that 3.0% povidone-iodine and 2% H₂O₂ with running loads could induce cartilage damage, and that 3.0% povidone-iodine solution induced more damage to the cartilage than 2% H₂O₂.

The effect of two different concentrations of povidone-iodine (PVI) solution, an antiseptic, on joint synovium was investigated. In Group I, 0.05 ml of 10% PVI was used, while in Group II, 0.05 ml of 2.5% of PVI was used. PVI solution was injected twice into both knee joints with one week interval. Ten rats were used as control and 70 rats as experimental.

In the two experimental groups four rats were sacrificed after 6, 12, 24 hours and three day and six rats at the end of the week after the second PVI injection. Synovial reaction was assessed histologically in both groups, based on the pathological parameters.

The results suggest that intra-articular injection of 10% and 2.5% PVI induces synovitis with focal ulceration which gradually subsides, and finally, the synovium becomes normal, though various degrees of subsynovial dense fibrosis complication arise.

Mechanical loading of articular cartilage affects the synthesis and degradation of matrix macromolecules. Much of the work in this area has involved mechanical loading of articular cartilage explants or cells in vitro and assessing biological responses at the mRNA and protein levels. In this study, we developed a new experimental technique to load an intact patellofemoral joint in vivo using muscle stimulation. The articular cartilages were cyclically loaded for one hour in a repeatable and measurable manner. Cartilage was harvested from central and peripheral regions of the femoral groove and patella, either immediately after loading or after a three hour recovery period. Total RNA was isolated from the articular cartilage and biological responses were assessed on the mRNA level using the reverse transcriptase-polymerase chain reaction. Articular cartilage from intact patellofemoral joints demonstrated heterogeneity at the mRNA level for six of the genes assessed independent of the loading protocol. Cyclical loading of cartilage in its native environment led to alterations in mRNA levels for a subset of molecules when assessed immediately after the loading period. However, the increases in TIMP-1 and decreases in bFGF mRNA levels were transient; being present immediately after load application but not after a three hour recovery period.

Objective: To assess effect of physical therapy including both physical agents and exercise on pain, physical functioning and quality of life in patients with knee osteoarthritis.

Methods: Twenty-seven patients (25 female and two male) with knee osteoarthritis were included in the study. Besides sociodemographic variables, presence of chronic diseases, analgesic use, recreational activites were recorded. A standard knee examination was performed and anteroposterior and lateral knee radiographs were obtained. Pain was measured using visual analogue scale (VAS), numeric scale and Likert scale. Pain, stiffness and physical function was assessed using Likert-scaled version of the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). For quality of life evaluation Medical Outcomes Study Short Form 36 (SF-36) was utilized. Evaluations were done at baseline and 1 month after completion of physical therapy sessions.

Results: Significant reduction of pain measurements namely VAS, numeric scale and Likert scale was observed as a result of physical treatment (p = 0.0001, p = 0.0001 and p = 0.001 respectively). In all 3 subscores of WOMAC (pain, stiffness and physical function) significant improvement was noted due to treatment (p = 0.0001, p = 0.012 and p = 0.0001 respectively). Similarly, physical functioning, role-physical, bodily pain and vitality and social functioning subscores demonstrated significant reductions after therapy. (p = 0.039, p = 0.001, p = 0.0001, p = 0.001 and p = 0.035 respectively).

Conclusion: Physical therapy including both physical agents and exercise leads to signifcant improvements in pain, physical functioning and quality of life. This change was demonstrated by both generic and disease specific outcome measures.

The purposes of this study are to describe the sonographic findings of the injured medial collateral ligament (MCL) of the knee, to perform a sonographic valgus stress test, and to correlate these findings in order to advance the proper treatment for these patients. We examined 23 patients with clinical diagnosis of MCL injury. We evaluated proximal and distal MCL thickness, free fluid, and avulsion fractures. In addition, we performed a sonographic valgus stress test in the stress and rest positions. We also examined the knee joint on the same side in 18 sex- and age-matched patients with no history of knee injury as a control. The average thickness of proximal MCL was 6.4 mm (range, 4.2–8.1 mm) in injured MCL and 4.3 mm (range, 3.2–6.2 mm) in normal MCL. The average thickness of distal MCL was 4.4 mm (range, 2.4–6.1 mm) in injured MCL and 3.1 mm (range, 2.1–4.1 mm) in normal MCL. The average joint space width of the injured knee at rest was 6.1 mm (range, 4.0–8.5 mm) and increased to 10.5 mm (range, 7.6–14.0 mm) after stress. The average joint space width of the normal knee at rest was 6.7 mm (range, 5.0–7.7 mm) and increased to 9.6 mm (range, 7.7–10.4 mm) after stress. In conclusion, the combination of the sonographic findings in MCL injury and the real-time sonography valgus stress test can support the clinical diagnosis and pinpoint the exact location of isolated MCL injury, thus advancing the proper treatment of the patient.

Purpose: Component position is critical in knee arthroplasty. We propose using a navigated knee axis (NKA) that is kinematically determined using a navigation system as an alignment reference, instead of defining the transepicondylar axis (TEA) with bony landmarks. This paper investigates whether this NKA should be computed over small arc segments versus over a full range of motion. Methods: Twelve unembalmed cadaver knees were tested. A navigation system computed the NKA for segments and for the full arc of motion in multiple planes. Results: The NKA computed near extension was different from the plane perpendicular to the mechanical axis (P > 0.005), while the NKA computed in flexion matched the TEA. Conclusion: The NKA determined from the full arc of motion was more reproducible and more closely estimated important knee parameters.

Objective: To evaluate the association between vitamin supplements and the incidence and progression of radiographic knee osteoarthritis (OA). Study Design: Prospective cohort. Methods: Men and women aged 40 years and older (N = 2239) participating in the community-based Clearwater Osteoarthritis Study (1988–current) with biennial, sequential radiographs. The Lawrence & Kellgren ordinal scale was used to determine evidence of the study outcome, radiographic knee OA, and progression of radiographic knee OA. The study exposure was baseline history of self-reported vitamin supplement usage. Results: Individuals without baseline knee OA who self-reported vitamin supplement usage were 12% less likely to develop knee OA than were those individuals who self-reported no vitamin supplement usage (RR = 0.88; 95% C.I. 0.86–0.89). Those with baseline knee OA who self-reported vitamin supplement usage were 7% less likely to experience knee OA progression than were those individuals who self-reported no vitamin supplement usage (RR = 0.93; 95% C.I. 0.87–0.99). Conclusion: After consideration of BMI, gender, age, history of knee trauma, exercise and vitamin supplement usage prior to study baseline, these findings suggest that vitamin supplement usage may play a protective role in knee OA. Vitamin supplements may be a cost-effective strategy to reduce the incidence and/or slow the progression of knee OA. As many approved OA drugs are accompanied by adverse side effects, the role of vitamin supplements in the development and progression of knee OA warrants further investigation.

Purpose: The increasing use of electrogoniometry (ELG) in clinical research requires the validation of different instrumentation. The purpose of this investigation was to examine the concurrent validity of an ELG system during activities of daily living. Methods: A total of 10 asymptomatic participants gave informed consent to participate. A Biometrics SG150 electrogoniometer was directly compared to a 12 camera three-dimensional motion analysis system during walking, stair ascent, stair descent, sit to stand, and stand to sit activities for the measurement of the right knee angle. Analysis of validity was undertaken by linear regression. Standard error of estimate (SEE), standardized SEE (SSEE), and Pearson's correlation coefficient r were computed for paired trials between systems for each functional activity. Results: The 95% confidence interval of SEE was reasonable between systems across walking (LCI = 2.43°; UCI = 2.91°), stair ascent (LCI = 2.09°; UCI = 2.42°), stair descent (LCI = 1.79°; UCI = 2.10°), sit to stand (LCI = 1.22°; UCI = 1.41°), and stand to sit (LCI = 1.17°; UCI = 1.34°). Pearson's correlation coefficient r across walking (LCI = 0.983; UCI = 0.990), stair ascent (LCI = 0.995; UCI = 0.997), stair descent (LCI = 0.995; UCI = 0.997), sit to stand (LCI = 0.998; UCI = 0.999), and stand to sit (LCI = 0.996; UCI = 0.997) was indicative of a strong linear relationship between systems. Conclusion: ELG is a valid method of measuring the knee angle during activities representative of daily living. The range is within that suggested to be acceptable for the clinical evaluation of patients with musculoskeletal conditions.

The Oxford Hip Score (OHS) and Oxford Knee Score (OKS) are validated, reliable and reproducible outcome measures, however their use retrospectively has not been examined. The aim of this prospective cohort study was to examine the accuracy and reliability of patients' ability to recall their OHS and OKS in a retrospective manner. A total of 137 patients undergoing primary hip (40) or primary knee (97) arthroplasty with a mean age of 70.8 years (range, 47–88) and a mean time to follow up of 27.2 months (range, 6–46) were included in the study. The mean retrospective OHS and OKS decreased compared to the pre-operative score (OHS = 1.6 ± SD, p = 0.36, OKS = 4.7 ± SD, p < 0.001). There was only a weak positive relationship between the actual pre-operative scores and the retrospective scores (OHS: r² = 0.30, OKS: r² = 0.19). Bland–Altman analysis demonstrated 95% limits of agreement between scores of -19.9 to 23.1 for the OHS and -15.3 to 24.8 for the OKS. This study shows that patients are poor at retrospectively recalling their pre-operative OHS and OKS and therefore these scores should not be used in a retrospective manner.

Objective: To evaluate whether 60${}^{\circ }$ and 90${}^{\circ }$ V-shaped osteotomies in sheep femurs have statistically significant differences when submitted to compressive strength tests. Material and Methods: A total of 30 left femurs of recently slaughtered sheep were removed, the proximal segment was discarded, and the bones were randomly divided into two groups of 15 specimens each. The bones underwent distal osteotomy at the supracondylar region at a 90${}^{\circ }$ angle between cuts, in group 1, and at a 60${}^{\circ }$ angle in group 2. The osteotomy was V-shaped and the distal apex started in the lateral face of the femur; medial cortical bone remained intact. Compressive tests were conducted, and four points of the deformation curve were collected for the calculation of the deformation rate using an interpolation scheme. Deformation patterns were evaluated according to two groups: intercondylar fracture and medial cortical fracture. Results: Group 1 had a mean resistance to failure to compressive load of 232kgf (SD 59.551; 150-400), whereas in group 2, mean resistance to failure to compressive load was 157.13kgf (SD 67.4; 70-346); this difference was statistically significant ($p=0.000619$, Kruskal–Wallis). Conclusions: Osteotomy at a 90${}^{\circ }$ angle had a greater resistance to compression and resulted in less weakening of the distal area of the femur after osteotomy. There were no differences in the pattern of fracture generated by compression according to osteotomy angle.

In this paper, several finite element models of an equine stifle joint with varying meniscal properties and attachments are compared to understand the effects of meniscal attachment complexity and material property changes on bone stresses. We found that the complexity in the meniscal attachment is critical when evaluating tensile stresses in the bone. We also demonstrate that simplified material properties may be justified when the relationship between each material property and the desired output variables is well understood. The choice of the most efficient, and yet appropriate, meniscal modeling method depends on the goals of the model.

Purpose: Most interference screws (IFS) for anterior cruciate ligament (ACL) reconstruction are manufactured from traditional materials like titanium. The advent of degradable metals (i.e. magnesium (Mg) alloys) has shown great promise for numerous orthopedic applications, including IFS for ACL replacement. Questions surrounding the mechanical integrity of degradable Mg alloys, as well as the impact of design changes on behavior, are still unanswered. The purpose of this research was to determine the impact of thread shape, diameter and screw taper on pullout strength of Mg-based IFS. Methods: Four different thread shapes were modeled, and analyzed, using finite element analysis. It was hypothesized that the thread shape, diameter and taper of the screw would significantly impact the pullout performance of the screw. Results: A buttress design resulted in the highest reaction (pullout) force (1247N) providing the greatest hold. Conclusion: Results of this study indicate that design factors impact pullout force and suggest thread shape, taper, and major diameter having the greatest impact.

Purpose: This study was conducted to histopathologically compare the results of the administration of intra-articular PDRN and HA injections in experimentally induced OA in rats. Methods: Osteoarthritis of the knee joints was induced in a total of 30 rats. Rats were randomly divided into three groups; polydeoxyribonucleic (PDRN) acid group, hyaluronic acid (HA) group, and saline group. The PDRN group was injected with 12 mg/0.05 ccPDRN acid. The HA group was injected with 12 mg/0.05 ccHA, whereas the saline group was injected with 50 $\mu$l (0.05 cc) of 0.9% sodium chloride solution. All rats were sacrificed on postinjection day 29, and the right knee joints were prepared and evaluated histologically using the Mankin scoring system. Results: Total Mankin scores showed a significant difference among all groups ($p$ = 0.001). According to bilateral comparisons performed to identify the group that showed a difference, the total Mankin scores of the PDRN acid and HA groups were found to be significantly lower than those of the saline group. In PDRN acid group, tidemark continuity wasobserved in all specimen. Conclusion: Intra-articular injections of PDRN acid resulted in greater chondroprotective effects and less degeneration than those of HA and saline in experimentally induced OA of the knee joints in rats.

Introduction: One of the most challenging and serious complications associated with total joint arthroplasty is prosthetic joint infection (PJI). Advancements in prevention, diagnosis, and treatment of PJI seem promising. Accurate identification of the causal pathogen is a key factor for successful treatment and also for choosing antibiotic treatment. This study was aimed to evaluate the prevalence of PJI and distribution of causative pathogen using microbiological culture and pathological examination.

Methods: A retrospective descriptive study was conducted by collecting data from our center registry from 2018 to 2020. The inclusion criteria of this study were patients diagnosed with hip or knee PJI based on the diagnostic criteria for PJI. The exclusion criteria were incomplete microbiology data which were either refusal to participate or loss of contact. The data extracted from medical records are demographic data such as age, sex, and microbiology and pathological examination data.

Results: A total of 1359 total hip/ knee arthroplasty surgeries were performed during the years 2018–2020. Among them, 1031 were total knee arthroplasty (TKA) and 321 were total hip arthroplasties (THA). During the same period, a total of 52 patients with PJI were treated at our center. There were 31 knee PJI cases (59.61%) and 21 were hip PJI cases (40.38%). Microbiology culture and pathologic anatomy results showed gram positive Staphylococcus sp bacteria, which was the common causal pathogen of PJI. Negative culture results were found in 10/52 (19.23%) of cases.

Conclusions:Staphylococcus sp was the most common causal pathogen of Hip/ Knee PJI in our center. Relatively high rate of culture-negative PJI was observed in this study, further strategies are needed to increase the rate of causal pathogen isolation in hip/ knee PJI cases in our center.