Cam Type Research Articles

Evaluating the Relationship Between Ballet Dancers and Incidence of Femoroacetabular Impingement

Dance demands performers engage in rigorous artistic and physical movement patterns. Classical ballet dancers repeatedly perform extreme ranges of motion, which can lead to irregular stresses on the hip joints that may cause pathologies, such as femoroacetabular impingement of the cam, pincer, or mixed type. These pathologies can be detrimental in the long term to the dancing body. Is participation in classical ballet correlated to the incidence of femoroacetabular impingement? This paper will appraise the current evidence regarding hip injury incidence to identify potential factors, which may correlate with incidence of femoroacetabular impingement in ballet dancers.

Magnetic resonance imaging (MRI) in diagnosis of non-traumatic hip joint pain

Background: The hip is a significant weight bearing, highly mobile, ball-and-socket synovial joint. There are several reasons of hip pain, such as congenital and developmental, viral, arthritic, and malignant conditions. Magnetic resonance imaging is the method of choice for determining the severity of osseous, chondral, and soft-tissue abnormalities of the hip joint, as well as for characterizing numerous illnesses. This study investigate the role of MRI in identifying hip joint discomfort. Methods and Results: Seventy-five both sexes patients with unilateral or bilateral painful hip joint were examined. The patients with age ranged from 10 to 70 years (mean age 54.74 + 10.52years) were 42 males (mean age 51.44 + 11.50) and 33 females (mean age 42.75 + 12.24) with male to female ratio 1.3:1. All our patients subjected to careful history taking, thorough clinical examination, routine laboratory investigations and local examination of the diseased hip. The majority of patients were in the age group 40-50 years followed by the age group of 50-60 years, with a male preponderance. The commonest chief complaint, other than pain of the involved hip joint, was restricted movement. All patients underwent MRI examination of both hips using a TOSHIBA 1.5 Tesla MRI machine scanner. Unilateral hip involvement was more common than bilateral. The commonest hip disorder was osteoarthritis, followed by avascular necrosis (AVN) of femoral head, tendinopathy, bursitis, sacroiliitis, Cam type femoral-acetabular impingement, ischio-femoral- impingement and pertheʹs disease. Conclusion: The MRI is the diagnostic method of choice for evaluating hip issues. It can discover certain features that lead to an accurate diagnosis of the uncomfortable hip joint and play a vital role in treatment and monitoring of sick joint by doctors.

Characterizing femoroacetabular impingement in professional Nordic Skiers

ABSTRACT Objective Studies have shown a high prevalence of femoroacetabular impingement (FAI) among elite athletes yet there is a paucity of data on FAI in Nordic skiers. The purpose of this study was to determine the prevalence of radiographic FAI in professional Nordic Combined Skiers and Ski jumpers compared to controls and assess functional outcomes including hip range of motion (ROM) and pain in patients with radiographic evidence of FAI compared to those without it. Methods A cohort of elite Nordic Skiers underwent medical history, physical examination, and pelvic radiographs at their visit with a fellowship-trained sports medicine physician. On pelvis radiographs, Alpha angle>55 degrees was deemed cam-positive, and positive crossover signs, Tönnis<0, or LCEA>40 were deemed pincer positive. Further stratification was performed by sex, ski event type, hip pain, presence of cam lesions, and presence of pincer lesions. Spearman correlation matrix was performed to measure the association between radiographic measurements and ROM. Results Nineteen Nordic skiers and nineteen age, sex, and BMI matched controls were included in the study. There were no significant differences in age, sex, BMI, and hip pain between groups. While Nordic skiers demonstrated decreased ROM bilaterally on external rotation compared to controls, skiers had larger ROM bilaterally on extension, abduction, adduction compared to controls. Skiers were significantly more likely to have bilateral crossover sign and alpha angles>55 compared to controls. Subgroup analysis showed that Cam positive patients had higher flexion and adduction ROM and pincer positive patients had significantly higher flexion and abduction ROM compared to patients without cam and pincer lesions respectively. Patients with hip pain had significantly lower right hip abduction ROM compared to patients without hip pain. No significant correlations were seen between radiographic measurements and ROM. Conclusion Similar to other elite ‘hip heavy’ sport athletes, Nordic skiers gave a notably higher prevalence of radiographic cam and pincer type morphology and significantly higher ROM compared to nonathletic controls. Clinicians evaluating Nordic skiers should be aware of these baseline findings with respect to a possible elevated long-term risk of symptomatic FAI in these athletes as well as other conditions related to radiographic FAI.

ACETABULAR DYSPLASIA AND CAM MORPHOLOGY ARE FEATURES OF SEVERE HIP OSTEOARTHRITIS: FINDINGS FROM A CROSS-SECTIONAL STUDY IN UK BIOBANK

Purpose: Abnormalities in hip shape are thought to represent an important predisposing factor for the development of hip osteoarthritis (HOA). Whereas developmental dysplasia of the hip (DDH) is linked to early onset HOA, more subtle changes in hip shape are also thought to contribute to HOA. These include cam and pincer type morphology, which are thought to lead to femoro-acetabular impingement (FAI), and acetabular dysplasia. We aimed to (i) evaluate relationships between radiographic hip shape derived from UK Biobank DXA images, and osteoarthritis based on definitions of varying severity and (ii) determine to what extent radiographic hip shape-HOA relationships are modified by alpha angle (AA) and lateral centre edge angle (LCEA), reflecting cam morphology and acetabular dysplasia, respectively.

Complementary and Alternative Medicine among Inpatient Pediatric Under One Year of Age in Baghdad City-Iraq

The aim of this study to measure the prevalence of complementary and alternative medicine CAM (one type of CAM called saqua) use in acutely sick children (complaining from gastro intestinal symptom) and factors associated with it.

Rotor Profile Design and Motion Simulation Analysis of Hydrogen Circulating Pump

With the development of automotive fuel cells towards high power and high efficiency, higher requirements are put forward for the speed and boost ratio of hydrogen circulation pump, while high speed and boost ratio increase the pulsation characteristics and accelerate the aging of hydrogen fuel cells. Cam type hydrogen cycle pump has the advantages of compact structure, high efficiency under low boost ratio, and good adaptability to low temperature, so it has become an important research direction. The efficient and reasonable rotor profile design can improve the volumetric efficiency of the cam rotor pump. It can reduce the pressure pulsation and flow pulsation in the pump. The equation of multi-stage circular arc rotor profile is established according to the meshing principle of the rotor. Motion Simulation module in UG NX is employed to conduct dynamic interference detection of rotor mechanism and simulation analysis of rotor mechanism meshing motion on the rotating parts of the hydrogen circulating pump. So the angular velocity curve and meshing force change curve of the driven gear is obtained. In order to verify the rationality of rotor profile design, the meshing force is compared with the standard spur gear.

Femoracetabular impingement treated with surgical hip dislocation: Short-term results

Background and objectiveMost of the studies available in the literature related to the treatment of femoroacetabular impingement (FAA) with surgical hip dislocation (CLD) come from Europe and North America. This study describes the short-term results of the LQC technique for treating PFA in a cohort of Colombian patients. Patients and methodsWe retrospectively analysed 42 cases of PFA treated with LQC from 2006 to 2018. The same orthopaedic surgeon performed all surgeries. Clinical outcome was assessed using the Merle d’Aubigné scores, while radiological assessment was performed using the Tönnis score. ResultsFifteen women and 25 men were included in the study, with a mean age of 36.3 years. Two patients had bilateral symptomatic involvement. Of the 42 cases, there were 13 cam type, 11 pincer type and 18 mixed. Preoperatively, 31 hips were classified as poor and moderate, and 11 as good according to the Merle d’Aubigné scale. The preoperative Tönnis radiological classification showed grade 0 in half of the cases. The mean duration of follow-up was 24 months (12–37). The final postoperative Merle d’Aubigné scores classified 7 cases as poor or moderate, and 35 as good to excellent (p < 0.05). The postoperative Tönnis score showed no significant variation. As complications, one patient had heterotopic ossification, and three had trochanteric nonunion requiring refixation. ConclusionOur results suggest that the LQC technique for the treatment of patients with PFA shows satisfactory short-term results with a low complication rate. To our knowledge, this is the first report of results of the surgical procedure for hip dislocation in our region.

Acellular Matrix-Induced Chondrogenesis Technique Improves the Results of Chondral Lesions Associated With Femoroacetabular Impingement

The study's main objective was to evaluate, in the short-term, the result of the autologous acellular matrix-induced chondrogenesis (AMIC) technique in a selected group of patients with 2-4 cm2 full-thickness chondral lesions, undergoing hip arthroscopy for femoroacetabular impingement (FAI). A retrospective single-center Level IV case series of 25 patients (28 hips) who underwent an arthroscopic hip surgery with a liquid acellular collagen matrix. Inclusion criteria for implantation were FAI diagnosis (cam or pincer type), grade IV chondral lesions (Outerbridge size 2-4 cm2); Tönnis stage 0-II, minimum follow-up of 24 months, and 1 year (12-15 months) evaluation with very high field 3-T MRI arthrography. Exclusion criteria were Tönnis III, joint space <2 mm, center-edge angle <20°, and <24 months of follow-up. Clinical assessments involved symptoms duration until surgery, changes in physical and work activity and range of motion, modified Harris Hip Score, reporting percentages of patient acceptable symptomatic state (PASS) and minimal clinically important difference (MCID), pain with a VAS, and level of satisfaction. Radiological assessments: Tönnis stage, articular space, alpha and lateral center edge angle (Wiberg), and generated tissue characteristics at 1 year (based on the MOCART score), through 3-T MRI. 25 patients (28 hips) treated; 19 men and 6 women (mean age: 40.5 years; range: 25-55). Two women underwent joint replacement surgery. Thus, 23 patients (26 hips) were analyzed. At 29 months following surgery (range: 24-48), a significant improvement was obtained in all parameters assessed, focusing on the characteristics of the generated tissue in the MRI (MOCART scores). 95% of the patients met the MCID (improvement >12 points in the modified Harris Hip Score), and 100% scored >74 points, achieving the PASS. Patients' satisfaction was 86.6% (SD 16.4). All patients who practiced sports resumed them. The liquid AMIC is a safe technique that shows good clinical and radiological outcomes in a 2-year follow-up in patients with femoroacetabular impingement and grade IV acetabular 2-4 cm2 chondral defects. Level IV, retrospective case series.

A three-dimensional measurement method on MR arthrography of the hip to classify femoro-acetabular impingement

Purpose(1) To investigate correlations between different types of FAI and the ratio of acetabular volume (AV) to femoral head volume (FV) on MR arthrography. (2) To assess 2D/3D measurements in identifying different types of FAI by means of cut-off values of AV/FV ratio (AFR).Materials and methodsAlpha angle, cranial acetabular version, acetabular depth, lateral center edge angle, AV, and FV of 52 hip MR arthrography were measured. ANOVA test correlated different types of FAI with AFR. ROC curves classified FAI by cut-off values of AFR. Accuracy of 2D/3D measurements was calculated.ResultsANOVA test showed a significant difference of AFR (p value < 0.001) among the three types of FAI. The mean values of AFR were 0.64, 0.74, and 0.89 in cam, mixed, and pincer types, respectively. Cut-off values of AFR were 0.70 to distinguish cam types from mixed and pincer types, and 0.79 to distinguish pincer types from cam and mixed types. Cut-off values identified 100%, 73.9%, and 55.6% of pincer, cam, and mixed types. 2D and 3D classifications of FAI showed accuracy of 40.4% and 73.0%.Conclusions3D measurements were clearly more accurate than 2D measurements. Distinct cut-off values of AFR discriminated cam types from pincer types and identified pincer types in all cases. Cam and mixed types were not accurately recognized.

Sex differences in the prevalence of radiographic findings of structural hip deformities in patients with symptomatic femoroacetabular impingement.

ABSTRACTThe purpose of this study was to determine the sex differences in the overall prevalence of radiographic femoroacetabular impingement (FAI) deformity patients presenting with hip pain and to identify the most common radiographic findings in male and female patients. A geographic database was used to identify patients between the age of 14 and 50 years with hip pain from 2000 to 2016. A chart and radiographic review was performed to identify patients with cam, pincer and mixed-type FAI. A total of 374 (449 hips) out of 612 (695 hips) male patients and 771 (922 hips) out of 1281 (1447 hips) female patients had radiographic features consistent with FAI. Ninety-four male hips (20.9%) and 45 female hips (4.9%) had cam type, 20 male hips (4.5%) and 225 female hips (24.4%) had pincer type and 335 male hips (74.6%) and 652 female hips (70.7%) had mixed type. The overall prevalence of radiographic findings consistent with FAI in male and female patients with hip pain was 61.1% and 60.2%, respectively. Mixed type was the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°, and the most common radiographic finding for pincer-type FAI was a crossover sign. Male patients were found to have a higher prevalence of cam-type deformities, whereas female patients were found to have a higher prevalence of pincer-type deformities.

Maglev weft knitting needle driving modeling and PID controller design

Maglev driving method is a novel needle driving technology for weft knitting machine, which uses the non-contact hybrid magnetic driving method to replace the traditional cam type knitting needle driving method. This method can alleviate the problems of noise, heating and broken knitting needle during the operation of knitting machine. This paper designs a hybrid magnetic levitation needle drive structure. Based on the structure and driving mode, the equivalent magnetic circuit model and the axial mechanical model of the needle are established. The state equation is used to analyze the axial displacement response of the needle under setting voltage. Moreover, the closed-loop controller of the needle drive is optimized to make the needle have stable axial displacement response. A hybrid maglev needle driving experimental device is also designed. The relationship between the axial displacement and the coil driving voltage is calculated by using the analytical method and the numerical finite element method. The results show that the hybrid maglev knitting needle axial drive structure and drive control method can meet the requirements of needle drive height. This study provides a reference for the design of new hybrid magnetic suspension knitting machine.

Pinzamiento femoroacetabular tratado con luxación quirúrgica de la cadera: resultados a corto plazo

Background and objectiveMost of the studies available in the literature related to the treatment of femoroacetabular impingement (FAA) with surgical hip dislocation (CLD) come from Europe and North America. This study describes the short-term results of the LQC technique for treating PFA in a cohort of Colombian patients. Patients and methodsWe retrospectively analysed 42 cases of PFA treated with LQC from 2006 to 2018. The same orthopaedic surgeon performed all surgeries. Clinical outcome was assessed using the Merle d’Aubigné scores, while radiological assessment was performed using the Tönnis score. ResultsFifteen women and 25 men were included in the study, with a mean age of 36.3 years. Two patients had bilateral symptomatic involvement. Of the 42 cases, there were 13 cam type, 11 pincer type and 18 mixed. Preoperatively, 31 hips were classified as poor and moderate, and 11 as good according to the Merle d’Aubigné scale. The preoperative Tönnis radiological classification showed grade 0 in half of the cases. The mean duration of follow-up was 24 months (12 to 37). The final postoperative Merle d’Aubigné scores classified 7 cases as poor or moderate, and 35 as good to excellent (p<0.05). The postoperative Tönnis score showed no significant variation. As complications, one patient had heterotopic ossification, and three had trochanteric nonunion requiring refixation. ConclusionOur results suggest that the LQC technique for the treatment of patients with PFA shows satisfactory short-term results with a low complication rate. To our knowledge, this is the first report of results of the surgical procedure for hip dislocation in our region.

Clinical Outcomes of Hip Arthroscopy for Hip Labrum Calcification in Young and Middle-Aged Patients.

ObjectiveTo investigate the methods and outcomes of hip arthroscopy for hip labrum calcification, and to discuss the clinical, imaging, and intraoperative findings of hip labrum calcification.MethodsThis is a therapeutic case series study. From January 2015 to June 2018, 15 patients who met the inclusion and exclusion criteria were followed up for at least 2 years for an analysis on the outcomes of arthroscopy in the treatment of hip labrum calcification and the clinical, imaging, and intraoperative findings of the patients. There were eight males and seven females, with an average age of 38.9 ± 8.8 years (range, 23–50 years). The visual analog scale (VAS), the modified Harris hip score (mHSS), and the international hip outcome tool (iHOT‐12) were used to evaluate the outcomes of surgery.ResultsA total of 15 patients were followed up for at least 2 years (28.1 ± 2.9 months). The average calcified volume was 118.0 mm3 (range, 19.4–609.2 mm3) and calcified volume was related to the preoperative hip function score. Thirteen patients had pain in the groin area (86.7%). Labrum calcifications were located (according to the clock distribution) as follows: 14 patients were anterior and superior (11:00–3:00); 12 cases of femoroacetabular impingement (FAI) were observed during operation, including five cases of pincer type, two cases of cam type, and five cases of mixed type. VAS pain score means were 7.73 ± 1.28 before surgery, decreasing to 2.0 ± 0.89 and 1.73 ± 0.79 at 1 and 2 years post‐surgery, respectively. mHSS scores were 57.40 ± 6.23 before surgery and 82.10 ± 4.76 and 83.18 ± 4.07, 1 and 2 years post‐surgery, respectively; iHOT‐12 mean score pre‐surgery was 37.67 ± 4.85, increasing to 67.64 ± 5.30 and 72.18 ± 4.49, 1 and 2 years post‐surgery, respectively. Compared with preoperative values, postoperative VAS, mHSS, and iHOT‐12 scores were significantly improved (P < 0.01); iHOT‐12 scores also significantly decreased from 1 to 2 years postoperatively (P = 0.034). No patient had complications.ConclusionHip arthroscopy is an effective method for the treatment of hip labrum calcification. The size of calcification influenced preoperative symptoms and function. Long‐term irritation from FAI may be one important cause of labrum calcification.

Factors influencing the usage of complementary and alternative medicine by patients with cancer

IntroductionThe interest in CAM among cancer patients is constantly growing and about 50% already used CAM alongside cancer therapy. Little is known on the factors influencing patients' choice of type of CAM used. MethodsA questionnaire consisting of two validated instruments (the ASKU (Allgemeine Selbstwirksamkeit Kurzskala), the PAM 13-D (Patient Activation Measure) and the structured AKKOM questionnaire on CAM usage was distributed at a German university hospital. Results639 patients (male 32.9%, female 63.2%; gynecological cancer 41%, gastrointestinal 19.2%, urogenital 15.6%) took part. 60% had used CAM in the last 3 months (biological 73%, holistic 63%, mind-body-methods 62%). Participants up to 30 years preferred biologically (p = 0.001), while women with gynecological cancer favored holistic based methods (p < 0.0001). There was no association between patients' beliefs on cancer causes and the chosen CAM method. ConclusionImproving knowledge in patients on cancer etiology and treatments could facilitate the understanding of additional complementary treatments.

Outcomes of femoral de-rotation osteotomy for treatment of femoroacetabular impingement in adults with decreased femoral anteversion

Decreased femoral anteversion is an often overlooked factor in femoroacetabular impingement (FAI), with potential to exacerbate both cam and pincer type impingement, or itself be the primary cause. Femoral de-rotation osteotomy (FDO) is a surgical option for symptomatic patients with such underlying bony deformity. This study aimed to investigate outcomes of FDO for management of symptomatic FAI in the presence of decreased (<5°) femoral anteversion. Secondary aims were to describe the surgical technique and assess complications. This study included 33 cases (29 patients) with average pre-operative anteversion measuring –3.1° (true retroversion). At an average follow-up of 1.5 years (19.8 months), 97% reported significant improvement. The overall average post-operative International Hip Outcome Tool (iHOT-33) score of 70.6 points (r: 23–98) compared to the average pre-operative score of 42.8 points (r: 0–56) for the 11 patients with available pre-operative scores suggests an overall improvement. The minimal clinically important difference for the iHOT-33 is 6.1 points. Patients with both pre- and post-operative iHOT-33 scores available demonstrated a statistically and clinically significant improvement of 37.7 (r: 13–70) points. There were three cases (9%) of delayed union and two cases (6%) of non-union early in the series which prompted evolution of the technique. Locking screw removal was performed in 33% of patients for a resultant overall re-operation rate of 45%. The findings suggest improvement in patient-reported outcomes can be achieved with FDO for symptomatic FAI in the setting of decreased femoral anteversion (<5°).

Motion Simulation Analysis of the Horizontal Sealing Device for the Bulk Material Packaging Machine Based on SOLIDWORKS Motion

In the past, the horizontal sealing mechanism of the bulk material packaging machine has a cam type and a cylinder type. The cylinder type horizontal sealing mechanism has a great impact when the speed changes, while the cam type horizontal sealing mechanism will cause noise and vibration. In this paper, the three-dimensional model of horizontal sealing device for bulk material packaging machine is carried out by SOLIDWORKS software, and the motion simulation analysis is carried out by using the add-in SOLIDWORKS motion. The results show that the acceleration of the horizontal sealing head for the horizontal sealing device occurs in 1/4 and 3/4 of the entire movement cycle. The horizontal sealing device can adjust the speed to meet the horizontal sealing requirements of different packaging bags. The horizontal sealing device of the bulk material packaging machine designed in this paper provides a reference for improving the packaging efficiency of products.

The Evaluation Indicators of X-ray Radiographs for Femoroacetabular Impingement Syndrome

Objective: To explore the evaluation indicators of X-ray radiographs for femoroacetabular impingement (FAI) syndrome, and to propose therapeutic plans for FAI syndrome by using X-ray radiographs. Methods: From June 2016 to May 2018, patients who were diagnosed as FAI syndrome by hip joint anteroposterior radiographs in Second Yinzhou District Hospital were selected as research objects. After screening, the surgical treatment group included 52 cases, totally. Another 30 healthy adults who received X-ray radiography were included as the control group. Each included patient underwent minimally invasive surgery under hip arthroscopy. The efficacy indicators were evaluated, and the data were statistically analyzed. Results: By analyzing the basic data of the subjects, it was found that there was no significant difference in gender and body mass index between the healthy people and FAI patients (P &gt; 0.05), but the VAS and Harris scores of 7d, 30d, 90d, and 180d after surgery were significantly higher than those before the operation, and with the prolongation of the treatment time, the scores increased continuously, the difference had statistical significance (P &lt; 0.05). By analyzing patients' knee joint mobility, it was found that after therapy, the flexion, pronation, abduction, and extension of knee joint at 30d, 90d, and 180d were distinctly increased compared with those before therapy. Also, the difference had statistical significance (P &lt; 0.05) with the treatment time increasing; the X-ray films of hip joint of the subjects were observed, and it was found that there were healthy people, clamp type FAI, and cam type FAI three typical kinds. There were significant differences in the angle, eccentricity, depth of acetabulum, coverage rate of acetabulum, and CE angle among cam type patients, clamp type patients, and healthy people (P &lt; 0.05). Conclusion: The research in this study found that when using the X-ray radiographs to determine the FAI syndrome, the differences between the classification of FAI symptoms and the healthy adults were obvious. In addition, the knee joint gradually recovered significantly in the range of movement (RM) after treatments, thereby providing experimental basis for diagnosing and treating the FAI syndrome in the later clinical stage.

FUNCTIONAL OUTCOMES OF ARTHROSCOPIC TREATMENT IN 230 FEMOROACETABULAR IMPINGEMENT CASES.

ABSTRACTObjective: To analyze the functional outcomes after arthroscopic treatment of femoroacetabular impingement (FAI). Methods: 194 patients (131 males and 63 females), with a mean age of 39 (15-68) years old for men and 43 (16-58) years old for women. The average follow-up was 17 months (2 to 71). 103 patients presented Cam-type FAI, 102 mixed and 25 Pincer. “Unilateral” arthroscopy was performed in 161 cases, “Bilateral” (only once each side) in 46 cases and, “Multiple” (more than one procedure on the same hip) in 23. The female sex was prevalent in the Pincer type FAI (76%), while males were prevalent in Mixed and Cam type, 74.5% and 72.8%, respectively. Results: The mean HHSpre score was 63.7 and 87.1 for HHSpost, i.e. 73.11%. Differences appeared between “mixed” and “unilateral” groups. The complications percentage in this series was 18.7% and 7% progressed to total hip arthroplasty. Conclusion: The arthroscopic FAI treatment improved the postoperative clinical scores of these patients, especially in cases of mixed-type FAI, which presented a higher improvement rate. Insufficient femoral osteoplasty was the main cause for surgical re-intervention, particularly in the initial cases of this series. Level of Evidence II, Retrospective study.

Кинематический расчет и построение графиков высоты подъема и скорости толкателя тангенциальных кулачков с использованием программы MATHCAD

The article shows the design features of tangential cams with a rounded top, provides a method for determining the lifting height and speed of the pusher when the roller is rolling in a straight line and in contact with the actual profile of the cam. The formulas for the kinematic calculation of the tangential cam are refined taking into account the radius of the initial circumference of the shaft, the radius of the rounding of the cam tip and the value of the radius of the pusher roller. Calculations are given to determine the stroke and speed of the pusher when the roller is rolling on the sections of the straight and arc-shaped surface of tangential cams with a radius of rounding of 6 and 10 mm. Formulas are proposed for determining the lift of the pusher in the rolling section of the roller along the radius of the cam tip at a constant coefficient λ = 1 and λ = 1,5. Using the Mathcad program calculations are performed and combined graphs of the pusher lift and the change in its speed are constructed for two types of tangential cams

Inter-observer concordance in normal and pathological findings of the hip joint in plain radiographs.

Background and aim:The purpose of the study was to compare the data obtained by two independent observers and statistically analyse the results using Cohen’s K to highlight the concordance or discordance in the diagnosis of normality, pathology and, in particular, the type of femoroacetabular impingement (FAI) on plain films.Methods:the study was conducted retrospectively. The only inclusion criterium was the minimum age of 20 years. All patients underwent a radiographic examination of the pelvis in standard anteroposterior projection in orthostasis.Results:A hundred patients were evaluated. A good concordance between the two operators in the examination of normal hip joint (k= 0.68 right/ 0,74 left) was found; a similar grade of agreement was found for the analysis of “pincer” type FAI (k = 0.73 right, 0,67 left). The best results in concordance were achieved in the examination of “cam” type FAI (k= 0.82 right, 0,88 left), “mixed” type FAI (k = 0.85 right, 0,86 left), and in findings of “coxa profunda” (k = 0.92 right, 0,88 left).Conclusion:We found a good concordance between the two readers; a few cases of disagreement were found in the diagnosis of “pincer” type FAI and absence of disease. This discrepancy may be due to the different weight given by the single observer to the clinical indication that leads the patient to examination, but also by the difficulty of a not dedicated radiologist to show some subtle signs indicative of early FAI.