The Biomechanical Effect of Platform Switching on External- and Internal-Connection Implants

ObjectiveThe Thessaly test is a commonly used orthopedic test for meniscus tear evaluation. The study’s objective is to evaluate the degree of medial meniscal extrusion during different loading phases of the Thessaly test.MethodsA convenience sample of 60 healthy knees (35 participants) was examined and the data sets were collected from October 8, 2018 through February 8, 2019. Sonographic measurement of the degree of physiologic extrusion of the medial meniscus deep to the medial collateral ligament was taken by two examiners at six different loading phases: supine, standing, 5° knee-flexion with internal (IR)/external (ER) rotation and 20° knee-flexion with IR/ER. The difference in meniscal extrusion by knee position was compared with ANOVA. Interexaminer reproducibility assessment was analyzed using limits of agreement.ResultsThe mean meniscal extrusion for each position was—supine: 2.3 ± 0.5 mm, standing: 2.8 ± 0.8 mm, 5° IR: 2.3 ± 0.9 mm, 5° ER: 2.4 ± 0.7 mm, 20° IR: 1.9 ± 0.8 mm, and 20° ER: 2.3 ± 0.7 mm. Significant increase in extrusion was observed from supine to standing (p < 0.05) and from 20° IR to 20° ER (p = 0.015). Significant decreased measurement was observed from standing to 5° IR (p < 0.05), 5° ER (p < 0.05), 20° IR (p < 0.05) and 20° ER (p < 0.05). There is no significant change between 5° IR and 5° ER (p = 1.0). Agreement parameters revealed that the differences between examiner measurements were minimal; 75% of both examiners’ meniscal extrusion measurements were within 1.0 mm with 97% of measurements falling within 2.0 mm.ConclusionOur study’s novel findings showed various degrees of physiological extrusion of the medial meniscus in asymptomatic knees during the loading phases involved in the Thessaly test. Physiological MME does exist and should not be defaulted to pathologic meniscus as previously described. Agreement parameters suggest that measurement of meniscal extrusion during the Thessaly test is reproducible between different examiners.

AM bundle controls the anterior–posterior and rotational stability to a greater extent than the PL bundle — A cadaver study

Knee proprioception is an integral component of neuromuscular control system that stabilizes the joints, reducing incidence of injury. Knee injuries' incidences differ between genders. Knee rotation is a component of different knee injury mechanisms. Gender differences in knee proprioception in internal (IR) and external (ER) rotations are not sufficiently studied. To check whether proprioceptive acuity in IR and ER directions of knee rotation is inherently lower in women compared to men. Moreover, to assess gender difference in ranges of knee rotation. Thirty volunteers (15 women and 15 men) participated. Knee proprioception acuity and ranges of knee rotation were assessed using the knee rotatory kinesthetic device (KRKD). Proprioception was tested using absolute judgment task, subject's ability to discriminate different rotation movements (stimuli) randomly presented, then just notable difference (JND) was calculated; least difference accurately discriminated in 75% of trials. Women had lower proprioception acuity in IR than men (1.70∘± 0.79∘ and 1.12∘± 0.32∘, p= 0.011) respectively. Active IR (women: 41.29∘± 7.46∘, men 32.80∘± 3.64∘, p= 0.000), and passive IR (women: 53.43∘±11.67∘, men: 37.94∘± 5.22∘, p= 0.000) were higher in women compared to men. Active ER (women: 49.71∘± 11.37∘, men: 39.16∘± 5.46∘, p= 0.003), and passive ER (women: 62.29∘± 13.74∘, men: 48.89∘± 7.09∘, p= 0.002) were, also, higher in women. Gender difference in knee proprioception acuity was found in IR, which is the direction of rotation that anterior cruciate ligament (ACL) stabilize. Women's ranges of knee rotation are greater than men in both IR and ER.

Objectives:The objective of the study was to create a cadaveric model of hip capsule laxity and evaluate the biomechanical effects of a capsular shift used to treat hip instability on this model.Methods:Eight fresh frozen cadaveric hips, average age 58.5, were tested with a custom hip jig. To create the hip laxity model, the capsule was stretched in extension under 35Nm of torque for 1 hour in neutral rotation. Specimens went through a series of six testing conditions: intact, vented, stretched, capsulotomy, side to side repair, and capsular shift. Specimens were tested in internal (IR) and external (ER) rotational range of motion under 1.5 Nm of torque at 5 positions: 5° extension, 0°, 15°, 30° and 45° flexion. Maximum extension was measured at 5Nm torque, and femoral distraction under 40N and 80N of force. Following creation of the instability model, capsulotomy was performed just distal to and in line with the labrum from 12 o’clock to 4 o’clock through the entire substance of the iliofemoral ligament. Capsulotomies underwent two repairs, including a 1 cm capsular shift technique and side to side repair using #2 vicryl. Statistical analysis was performed using repeated measures ANOVA with TUKEY post-hoc analysis.Results:Analysis of the “stretched” state showed significantly increased IR at 5° ext, 0° flex, 15° flex, and 30° flex and increased distraction at 40N and 80N as compared to intact (Figure 1)(Table 1). Max extension increased by 6.6° between intact and stretched, however this was not statistically significant. Capsulotomy condition significantly increased ER and IR from intact at all flexion-extension positions. Furthermore, capsulotomy increased distraction at 40N and 80N, as well as max extension, as compared to intact. The repair restored IR back to the stretched state but not to the intact state at 5° ext and 0° flex (19.6° vs 24.5° and 21.8° vs 26.4°, respectively). The capsular shift significantly decreased IR compared to stretched state at 5° ext, 0°, and 15° flex, and at 5° ext and 0° compared to the vented state. Capsular shift restricted IR significantly more than repair at 5° ext, 0° flex, and 15° flex. Capsule shift and repair had similar effects on ER. Distraction distance at 40N and 80N was greater in the repair compared to the shift but this was not statistically significant. The capsular shift decreased distraction as compared to the stretched state but the repair did not. Maximum extension was significantly reduced back to the intact/vented state from the laxity state in the capsular shift but not in the repair.Conclusion:The instability model (stretched) was shown to have significantly greater range of motion, extension, and distraction than the intact condition. The greatest effects of capsular shift are seen with internal rotation, extension, and distraction with minimal effect on external rotation. The biomechanical effects of the capsular shift procedure in hip laxity patients show that its use can safely treat pathologic hip capsular laxity.

Transient and long-time kinetic responses of the cadaveric leg during internal and external foot rotation

Background: Water-polo is the water sport with the highest incidence of injuries, with shoulder pain being the most common one. The understanding of risk factors and guidance on preventive measures is essential in this sport discipline. The aim of this study was to determine the effects of a specific 6-week training plan on range of motion (ROM) and joint strength levels in a group of professional water-polo players. Methods: Quasi-experimental study with a sample of 28 participants (age: 20.1 ± 2.5 years; height: 176.9 ± 6.2 cm; body mass: 74.6 ± 8.1 kg). Three study groups, which consisted of one control group and two experimental groups, were established. Two repeated measurements, pre and post intervention, were performed. During these measurements, ROM of the glenohumeral joint was analyzed both in external (ER) and internal (IR) rotation, as well as the maximal isometric strength. Conclusions: The application of a training program improved glenohumeral joint ROM. ER and IR evolve differently in both shoulders. ER improved only in the throwing arm only in the group undergoing intervention but for the non-dominant side, improvements were observed in both ER and IR, regardless of whether or not they had followed the intervention plan. No improvements were observed in either the isometric strength or contralateral asymmetries.

BackgroundThere are limited studies reporting descriptive strength and range of motion in youth baseball players 12 years of age or younger.PurposeTo establish normative data for external (ER) and internal (IR) rotation range of motion (ROM), total arc range of motion (TROM), and isometric rotator cuff strength in youth baseball players, and to compare between the dominant throwing arm (D) to the non-dominant arm (ND).Study DesignCross-sectionalMethodsPatient population included 50 (5 to 12-year-old) uninjured, healthy athletes. ROM measurements were performed preseason using a goniometer for IR and ER in the supine position with the shoulder in 90 degrees of abduction (abd) with scapular stabilization. Isometric strength measurements for IR and ER were collected in both neutral and 90 degrees (deg) of abduction with the use of a hand-held dynamometer and recorded in pounds (lbs) utilizing a “make” test. Descriptive statistics were obtained for all measures.ResultsAll data were analyzed as a single group (average age: 9.02). No significant difference in average total arc of PROM (ER+IR=Total Arc) on the D side compared to the ND side (136.7 ± 12.7 deg vs. 134.3 ± 12.3 deg). There were statistically significant differences between ER ROM (102.2 ± 7.7 deg vs. 96.8 ± 7.4 deg) and IR ROM (34.4 ± 9.0 deg vs. 37.5 ± 9.5 deg) between D versus ND arms (p= .000, .006 respectively). Mean ER strength in neutral (13.6 ± 3.4 and 12.8 ± 3.6 lbs) and 90 deg abduction (12.3 ± 3.4 and 12.5 ± 4.3 lbs) did were not significantly different between D and ND arms, respectively. Mean IR strength in neutral (18.0 ± 6.0 and 15.7 ± 4.7 lbs) and 90 deg abd (16.4 ± 5.6 and 15.0 ± 5.7 lbs) was significantly greater in the D arm vs ND arm, respectively (p=.000, .001).ConclusionThese data can provide descriptive information for clinicians who treat very young baseball players. These data show sport specific adaptations occur at very young ages (5-12) and are similar to prior reports on adolescent, high school and professional baseball players regarding upper extremity ROM and rotator cuff strength.Level of Evidence3

Shoulder injuries are frequent in rugby, and muscular deficiency and/or imbalance of the internal (IR) and external (ER) shoulder rotators are considered as probable mechanisms of shoulder injuries. The purpose of this study was to investigate whether the rotators strength imbalances occur in rugby players by comparing IR and ER strength and ER/IR ratios between rugby players (RP) and nonathletic subjects. Fourteen RP and 19 healthy nonathletic subjects were evaluated in this cross-sectional controlled study with a Con-Trex ((R)) dynamometer. IR and ER isokinetic strength were performed at 60 degrees . s (-1) and 240 degrees . s (-1) in concentric, and 60 degrees . s (-1) in eccentric, for both sides. Strength values were higher for RP than nonathletic ones ( P<0.05), but if peak torque was normalised to body weight, there were no significant differences. There was no significant effect of laterality on the IR and ER peak torque, and no significant influence of rugby and/or laterality on the ER/IR ratio. In conclusions, our results reported no rotators muscles imbalance in RP as a possible risk factor of glenohumeral injury.

Normative descriptive study. Exploring the isokinetic work ratios of eccentric antagonist/concentric agonist shoulder rotators in the late cocking and deceleration phases of a forehand overhead smash in badminton players. Comparing the work ratios between dominant and nondominant shoulders. The strength of shoulder muscles for badminton players has been studied but there is little information on the work output of these muscles for a specific range of movement. Twenty-five skilled men who play badminton at club level with a mean age of 29.4 years (SD = 6.1) were measured for concentric and eccentric isokinetic work (joules) of shoulder internal (IR) and external (ER) rotators on both upper extremities at 120 degrees/s. Bilateral isokinetic work ratios for eccentric IR/concentric ER between 60 degrees and 90 degrees of shoulder external rotation were calculated to denote strength profile in the late cocking phase of the badminton smash. Work ratios for eccentric ER/concentric IR between 10 degrees external rotation and 30 degrees internal rotation were calculated to denote strength profile in the deceleration phase of the badminton smash. The respective work ratios were compared between both shoulders. The eccentric IR/concentric ER work ratios in late cocking were 1.9:1 and 1.3:1 (P = 0.001) for the dominant and nondominant shoulders, respectively. The eccentric ER/concentric IR work ratios in the deceleration phase were 1.1:1 and 1.3:1 (P = 0.003) for the dominant and nondominant shoulders, respectively. The work ratios of eccentric antagonist/concentric agonist are different between dominant and nondominant shoulders of skilled badminton players. Rehabilitation for injuries of these athletes should aim at developing the optimal antagonist/agonist work ratios to return them to this sport.

Large vestibular aqueduct syndrome (LVAS) is one of the common causes of hearing loss (HL). All prior studies have reported some anomalies associated with LVAS by imaging techniques. This study was undertaken to determine prevalence of LVAS in our temporal bone (TB) collection and its relationship to other systemic or otologic anomalies. Retrospective, TB histopathologic study. Anteroposterior diameters of internal (IA) and external (EA) apertures were measured in 40 normal TBs (40 cases). TBs were considered as large vestibular aqueduct (LVA) if width of apertures was 95% greater than "normals." Systemic and otologic anomalies and histopathology of ears with LVAS were noted. Of 1,608 non-"normal" TBs, 63 had LVA. There was negative correlation between IA and EA in 48 TBs with only enlarged IA. Fifteen TBs with enlarged EA always had enlarged IA and were therefore considered as LVAS. The most common pathologic condition was congenital heart anomaly. The most common syndrome or dysplasia was Mondini's. The most common anomalies of external and middle ears were dehiscent facial nerves, low set auricles, and ossicular deformities. Inner ear anomalies included modiolar deficiencies, hair cell loss, interscalar septum defects, and strial atrophy. There was no record of family history of HL, head injury, or craniofacial, branchial, or thyroidal abnormalities. Because HL associated with LVAS may be attributed to other ear anomalies, it is important to investigate other inner ear problems and system diagnoses that may indicate a syndrome in patients with radiologically diagnosed LVAS.

In youth handball players, knowledge about the development of soft-tissue adaptation and humeral retrotorsion is limited. The purpose of this study was to investigate differences in adaptations in the glenohumeral rotational range of motion and humeral retrotorsion of the throwing arm between male and female youth elite handball players. One-hundred and thirty-eight youth elite handball players (mean age: 14.1 ± 0.7years) were assessed for glenohumeral external (ER) and internal (IR) rotational ranges of motion and humeral retrotorsion (HRT) by means of a manual goniometer and a portable ultrasound device. Sports-specific adaptations between the dominant and non-dominant shoulders and between male and female adolescents were calculated. Handball players showed side-to-side differences in IR and ER in the throwing shoulder. HRT did not correlate with the measurements of rotational ROM of the throwing arm. Male athletes showed a more pronounced glenohumeral internal rotation deficit than female athletes (13.1° ± 22.8° vs. 5.1° ± 14.0°, p = 0.014). Adaptations in HRT but no sex differences could be seen in the throwing shoulder (16.5° ± 9.6°) compared to the non-throwing shoulder (13.5° ± 9.4°, p < 0.001). Loss of internal rotation and gain in external rotation in youth handball players seem to be more related to adaptive changes in the soft-tissues than to HRT. Male athletes showed stronger throwing-related adaptations in the rotational range of motion but not in humeral torsion in their dominant shoulder than female athletes. Cross-sectional study, Level II.

Problem Statement: In joint movement, agonist and antagonist muscle strength, as well as the length and the shortness of these muscles is an important parameter. Muscle shortness is one of the factor that responsible of sports injuries. Shoulder is one of the most injured joint in Judo. In this joint, determination of the relationship between muscle shortness and agonist-antagonist muscles strength will be effective to increase muscle strength, sportive performance and prevent sports injuries. Purpose of Study: This study was conducted to determine the relationship between pectoralis minor (PM) muscle length and shoulder internal(IR)/external(ER) rotation isokinetic muscle strength in Judo athletes. Methods: The study included 80 (56 males, 24 female) professional Judo athletes aged between 14-25 (mean 17,31±2,51). Isokinetic muscle strength was assessed by ISOMED 2000® device. Pectoralis minor length was evaluated using a flexible tape measure in resting position. The assessments were made bilaterally. Findings and Results: There was a strong and statistically significant correlation between the PM length and the shoulder IR and ER peak torque values at both angular velocities and both sides (p <0,01). Conclusions and Recommendations: It was determined that the relationship between the length of the PM muscle and the internal and external rotator muscle strength of Judo athletes. Therefore, we think that by increasing shoulder muscle strength to enhance sportive performance, stretching exercises for PM muscle shortening should be added to training programs.

The isokinetic rotator cuff strength ratios in overhead athletes: Assessment and exercise effect

Numerical evaluation of the Kramers-Kronig analysis used in reflection spectroscopy has been carried out in order to find out optimal experimental conditions that minimize errors on complex refractive indices. By the use of the spectral simulation and the complex refractive index based on dispersion theory, we compared six kinds of experimental setups: external (EXT), internal (INT), and attenuated total reflection (ATR) geometries for both perpendicular (s)-and parallel (p)-polarized incident beams. Applying the so-called Dignam method to the simulated spectra, we evaluated the errors on the complex refractive indices. As far as physical and chemical properties of a sample are not taken into account, following conclusions are obtained: (1) ATR technique with p-polarization gives the smallest error at an optimal incident angle near by the critical angle.(2) If two kinds of measurements are permitted, the combined use of INT with s-polarization and ATR with p-polarization minimizes the error.

Knee joint laxity affects muscle activation patterns in the healthy knee