Surgical accuracy of image-free versus image-based robotic-assisted total knee arthroplasty.

BACKGROUND: This study investigated the accuracy in achieving proper lower limb alignment and component positions after total knee replacement (TKR) with image-free and image-based robotic-assisted TKR. METHODS: A total of 129 patients (166 knees) suffering from end-stage knee arthritis who underwent TKA operated by robotic-assisted surgery between the years 2018 and mid-2021 were recruited. Radiological outcomes were compared between image-free and image-based robotic-assisted surgical systems. RESULTS: There were significant differences between the two robotic systems when comparing the mean planned component alignment and the mean measured alignment on radiographs, in which the image-free robotic-assisted system was more varus, whereas the image-based robotic-assisted system was more valgus for both the mean femoral and tibial component coronal alignment (p < 0.001). For tibial component sagittal alignment, the image-based group had a larger deviation from the planned posterior slope (p < 0.001). CONCLUSION: Image-free and image-based robotic assisted TKR had differing accuracy in femoral and tibial alignment.

Effects of Gluteus Medius and Biceps Femoris Stimulation on Reduction of Knee Abduction Moment During a Landing Task.

Anterior cruciate ligament injury prevention should focus primarily on reduction of the knee abduction moment (KAM) in landing tasks. Gluteus medius and hamstring forces are considered to decrease KAM during landing. The effects of different muscle stimulations on KAM reduction were compared using 2 electrode sizes (standard 38 cm2 and half size 19 cm2) during a landing task. Twelve young healthy female adults (22.3 [3.6] y, 1.62 [0.02] m, 50.2 [4.7] kg) were recruited. KAM was calculated under 3 conditions of muscle stimulation (gluteus medius, biceps femoris, and both gluteus medius, and biceps femoris) using 2 electrode sizes, respectively versus no stimulation during a landing task. A repeated-measures analysis of variance determined that KAM differed significantly among stimulation conditions and post hoc analysis revealed that KAM was significantly decreased in conditions of stimulating either the gluteus medius (P < .001) or the biceps femoris (P < .001) with the standard electrode size, and condition of stimulating both gluteus medius and biceps femoris with half-size electrode (P = .012) when compared with the control condition. Therefore, stimulation on the gluteus medius, the biceps femoris, or both muscles could be implemented for the examination of anterior cruciate ligament injury potential.

An individually moulded insole with 5-mm medial arch support reduces peak impact and loading at the heel after a one-hour treadmill run.

BACKGROUND: Foot pain experienced by long-distance runners could be relieved by functional insoles which aim at evenly distributing the plantar pressure. RESEARCH QUESTION: We hypothesised that an individually moulded insole with medial arch support would reduce the impact and loading under the heel and metatarsal regions. METHODS: Twelve male recreational runners ran on a treadmill at 10 km/h for 1 hour with flat insoles and medial arch supported insoles. A pressure insole system (Novel Pedar, Germany) was used to obtain the peak pressure, peak force, time normalised pressure-time integrals, and the percentage of the total force-time integrals under 10 regions. RESULTS: Medial arch supported insoles reduced the peak force under the heel (medial: -15.3%, p = 0.001; lateral: -19.2%, p = 0.037) during the initial run, and reduced peak pressure under the heel (medial: -13.3%, p = 0.005; lateral: -9.9%, p = 0.006), and peak force under the medial heel (-17.8%, p = 0.006) after the run. The percentage of the total force-time integrals under the heel was reduced (medial: -23.8%, p = 0.004; lateral: -13.6%, p = 0.022) after the run. No significant difference was found under the metatarsal regions. There is shift of load from the metatarsal regions to the medial mid-foot as indicated by the change of the percentage of total force-time integrals. SIGNIFICANCE: Medial arch supported insoles were effective in reducing the impact and loading under the heel region in prolonged running on a treadmill. LEVEL OF EVIDENCE: Controlled laboratory study, Level V.

Myoelectric stimulation on peroneal muscles with electrodes of the muscle belly size attached to the upper shank gives the best effect in resisting simulated ankle sprain motion.

Ankle sprain is a common sports related injury that may be caused by incorrect positioning of the foot prior to and at initial contact during landing from a jump or gait. Furthermore a delayed reaction of the peroneal muscle may also contribute to the injury mechanism. A recent study demonstrated that myoelectric stimulation of the peroneal muscles within 15 ms of a simulated inversion event would significantly resist an ankle spraining motion. This study further investigated its effect with three different electrode sizes and three different lateral shank attachment positions. Twelve male subjects with healthy ankles performed simulated ankle supination spraining motion on a pair of mechanical sprain simulators. A pair of electrodes of one of the three sizes (large, medium, small) was attached to one of the three positions (upper 1/4, middle, lower 1/4) along the lateral shank to deliver an electrical signal of 130 V for 0.5s when the sprain simulator started. Ankle kinematics data were collected by a tri-axial gyroscope motion sensor and the peak inward heel tilting velocity was obtained to represent the effect in resisting the simulated ankle spraining motion. Repeated measures one-way analysis of variance was performed and showed a significant drop from 273.3 (control, no stimulation) to 215.8 deg/s (21%) when small electrodes were attached to the upper 1/4 position. Decrease was found in all other conditions but the drops (11-18%) were not statistically significant. The small electrodes used in this study fitted the width of the peroneal muscle belly at the upper 1/4 position, so the electrical current may have well flowed to the motor points of the muscles to initiate quick contraction.

Upper limb muscle fatigue during prolonged Boccia games with underarm throwing technique.

This study investigated the acute fatigue pattern in neuromuscular activity after a simulated Boccia game and the effect of fatigue pattern on sport performance. Nine elite Boccia athletes were tested before, during, and after a simulated game. Maximum ball speed was captured with video, and the target hitting rate and rating of perceived exertion (RPE) score were collected and analyzed. Electromyography signals from the upper trapezius, anterior deltoid, posterior deltoid, biceps brachii, triceps brachii, and wrist extensor muscles were collected by surface electrode and were evaluated with mean power frequency (MPF). Only the upper trapezius muscle showed fatigue as demonstrated by a reduction of MPF of 8% (p = 0.027) when comparing the first and last throws in a simulated game. Subjective RPE score increased during the game (118%, p = 0.004), and sports performance in terms of maximum ball speed (-12%, p = 0.004) and target hitting rate (-25%, p = 0.004) also deteriorated. In conclusion, fatigue on the upper trapezius muscle was demonstrated in elite Boccia athletes following a prolonged Boccia game and may have affected Boccia performance. Preventative measures against upper trapezius muscle fatigue and endurance training for synergists of the upper trapezius muscle may be considered in future studies.

Myoelectric stimulation on peroneal muscles resists simulated ankle sprain motion.

The inadequate reaction time of the peroneal muscles in response to an incorrect foot contact event has been proposed as one of the etiological factors contributing to ankle joint inversion injury. Thus, the current study aimed to investigate the efficacy of a myoelectric stimulation applied to the peroneal muscles in the prevention of a simulated ankle inversion trauma. Ten healthy male subjects performed simulated inversion and supination tests on a pair of mechanical sprain simulators. An electrical signal was delivered to the peroneal muscles of the subjects through a pair of electrode pads. The start of the stimulus was synchronized with the drop of the sprain simulator's platform. In order to determine the maximum delay time which the stimulus could still resist the simulated ankle sprain motion, different delay time were test (0, 5, 10, and 15ms). Together with the control trial (no stimulus), there were 5 testing conditions for both simulated inversion and supination test. The effect was quantified by the drop in maximum ankle tilting angle and angular velocity, as determined by a motion analysis system with a standard laboratory procedure. Results showed that the myoelectric stimulation was effective in all conditions except the one with myoelectric stimulus delayed for 15ms in simulated supination test. It is concluded that myoelectric stimulation on peroneal muscles could resist an ankle spraining motion.

Differentiation of ankle sprain motion and common sporting motion by ankle inversion velocity.

This study investigated the ankle inversion and inversion velocity between various common motions in sports and simulated sprain motion, in order to provide a threshold for ankle sprain risk identification. The experiment was composed of two parts: firstly, ten male subjects wore a pair of sport shoes and performed ten trials of running, cutting, jump-landing and stepping-down motions. Secondly, five subjects performed five trials of simulated sprain motion by a supination sprain simulator. The motions were analyzed by an eight-camera motion capture system at 120 Hz. A force plate was employed to record the vertical ground reaction force and locate the foot strike time for common sporting motions. Ankle inversion and inversion velocity were calculated by a standard lower extremity biomechanics calculation procedure. Profiles of vertical ground reaction force, ankle inversion angle and ankle inversion velocity were obtained. Results suggested that the ankle was kept in an everted position during the stance. The maximum ankle inversion velocity ranged from 22.5 to 85.1 degrees/s and 114.0 to 202.5 degrees/s for the four tested motions and simulated sprain motion respectively. Together with the ankle inversion velocity reported in the injury case (623 degrees/s), a threshold of ankle inversion velocity of 300 degrees/s was suggested for the identification of ankle sprain. The information obtained in this study can serve as a basis for the development of an active protection apparatus for reducing ankle sprain injury.

Treatment of an osteoporotic Hoffa fracture.

Two patients with Hoffa fracture of the knee, both suffering from poliomyelitis are reported. Both had unicondylar coronal plane fracture of the medial femoral condyle. The patients were treated with open reduction and screw fixation. Due to poor screw purchase, reoperation was necessary in one patient. The results were satisfactory in both patients.

Radiocarbon dating of charcoal and bone collagen associated with early pottery at Yuchanyan Cave, Hunan Province, China.

Yuchanyan Cave in Daoxian County, Hunan Province (People's Republic of China), yielded fragmentary remains of 2 or more ceramic vessels, in addition to large amounts of ash, a rich animal bone assemblage, cobble and flake artifacts, bone tools, and shell tools. The artifacts indicate that the cave was a Late Paleolithic foragers' camp. Here we report on the radiocarbon ages of the sediments based on analyses of charcoal and bone collagen. The best-preserved charcoal and bone samples were identified by prescreening in the field and laboratory. The dates range from around 21,000 to 13,800 cal BP. We show that the age of the ancient pottery ranges between 18,300 and 15,430 cal BP. Charcoal and bone collagen samples located above and below one of the fragments produced dates of around 18,000. These ceramic potsherds therefore provide some of the earliest evidence for pottery making in China.