Kicking in or kicking out? The role of the individual motor expertise in predicting the outcome of rugby actions.

In sports, understanding others' actions represents a fundamental skill that allows players to predict the outcome of teammates' and opponents' actions and counteract them properly. While it is well known that motor expertise sets better premises for predicting the result of an observed sports action, it remains untested whether this principle applies to a team where players cover different positions that imply different motor repertoires. To test this hypothesis, we selected rugby as a paradigmatic example in which only one or two players out of 22 train and perform placed kicks. We administered a placed kick outcome prediction task to three groups of participants, namely, rugby kickers, rugby non-kickers, and controls, thus spanning over different combinations of motor expertise and visual experience. Kickers outperformed both their non-kicking teammates and controls in overall prediction accuracy. We documented how the viewpoint of observation, the expertise of the observed kicker, and the position of the kick on the court influenced the prediction performance across the three groups. Finally, we revealed that within rugby players, the degree of motor expertise (but not the visual experience) causally affects accuracy, and such a result stands even after accounting for the level of visual experience. These findings extend the role of motor expertise in decoding and predicting others' behaviors to sports teammates, among which every member is equipped with a position-specific motor repertoire, advocating for new motor training procedures combining the gestures to-be-performed with those to-be-faced.

Passive shoulder exoskeleton support partially mitigates fatigue-induced effects in overhead work.

BACKGROUND: Despite the potential of occupational passive shoulder exoskeletons (PSEs) to relieve overhead work, limited insights in overhead work precision performance impedes large-scale adoption in industry. OBJECTIVE: To investigate the effect of PSE support on the reduction in task performance caused by physical fatigue. METHODS: This experiment consisted of a randomized, counterbalanced cross-over design comparing Exo4Work PSE support and no support, in a physically fatigued state and a control condition. Precision performance was determined using execution speed and drilling errors. Muscle activity and shoulder joint kinematics were recorded. RESULTS: Fatigue altered task performance, shoulder joint kinematics, muscle activity and subjective experience during overhead work. The PSE support mitigated the fatigue-induced changes in shoulder kinematics. Additionally, a part of the fatigue-induced co-activation of shoulder stabilizing muscles was avoided when working with the PSE. The PSE support also reduced the activity of the anterior and medial deltoid. CONCLUSION: Physical fatigue provokes compensatory movements and increased co-contraction of muscles when executing overhead work. These fatigue-induced alterations are generally believed to increase the overall musculoskeletal load. The support provided by the PSE reduced muscle activity of muscles working to elevate the arm, but also partially mitigated those fatigue-induced effects. SIGNIFICANCE: This study shows that the effect of PSE support on precision performance is limited, and suggested that, apart from the known effects of PSE support during overhead work, wearing the exoskeleton in a physically fatigued state may provide additional advantages.

The Exo4Work shoulder exoskeleton effectively reduces muscle and joint loading during simulated occupational tasks above shoulder height.

INTRODUCTION: Excessive physical shoulder musculoskeletal loading (muscle and joint contact forces), known to contribute to work-related shoulder disorders, can be reduced by a passive shoulder exoskeleton during quasi-static tasks. However, its effect on neighboring joints i.e. elbow, lower back, hip, and knee and its effect on joint contact forces have not been investigated. Furthermore, the effect of the exoskeleton's assistance versus movement adaptation when wearing the exoskeleton on musculoskeletal loading remains unexplored. METHODS: 3D motion capture and ground reaction forces were measured while 16 participants performed 5 simulated occupational tasks with and without the exoskeleton. A musculoskeletal modeling workflow was used to calculate musculoskeletal loading. Shoulder muscle fatigue was quantified using surface EMG. In addition, exoskeletons usability was quantified using the system usability scale. RESULTS: When wearing the passive shoulder exoskeleton, shoulder and elbow musculoskeletal loading decreased during the high lift and overhead wiring task, without increasing the musculoskeletal load at the back, hip and knee. In contrast, musculoskeletal loading in the shoulder, as well as in the knee increased while lifting a box from the ground to knee height and from elbow height to shoulder height. When wearing the exoskeleton, muscle activity of the Trapezius descendens, Deltoideus medius and Biceps brachii were reduced during the high lift. CONCLUSION: The passive shoulder exoskeleton reduces musculoskeletal loading in the lower back, shoulder and elbow during simulated occupational tasks above shoulder height. In contrast, for tasks below shoulder height, the use of the exoskeleton needs to be critically reviewed to avoid increased musculoskeletal loading also in neighboring joints due to altered movement execution when wearing the exoskeleton.

An Occupational Shoulder Exoskeleton Reduces Muscle Activity and Fatigue During Overhead Work.

OBJECTIVE: This paper assesses the effect of a passive shoulder exoskeleton prototype, Exo4Work, on muscle activity, muscle fatigue and subjective experience during simulated occupational overhead and non-overhead work. METHODS: Twenty-two healthy males performed six simulated industrial tasks with and without Exo4Work exoskeleton in a randomized counterbalanced cross-over design. During these tasks electromyography, heart rate, metabolic cost, subjective parameters and performance parameters were acquired. The effect of the exoskeleton and the body side on these parameters was investigated. RESULTS: Anterior deltoid activity and fatigue reduced up to 16% and 41%, respectively, during isometric overhead work, and minimized hindrance of the device during non-overhead tasks. Wearing the exoskeleton increased feelings of frustration and increased discomfort in the areas where the exoskeleton and the body interfaced. The assistive effect of the exoskeleton was less prominent during dynamic tasks. CONCLUSION: This exoskeleton may reduce muscle activity and delay development of muscle fatigue in an overhead working scenario. For dynamic applications, the exoskeleton's assistive profile, which mimics the gravitational torque of the arm, is potentially sub-optimal. SIGNIFICANCE: This evaluation paper is the first to report reduced muscle fatigue and activity when working with an occupational shoulder exoskeleton providing one third of the gravitational torque of the arm during overhead work. These results stress the potential of occupational shoulder exoskeletons in overhead working situations and may direct towards longitudinal field experiments. Additionally, this experiment may stimulate future work to further investigate the effect of different assistive profiles.

Arthroscopic vs open ankle arthrodesis: A prospective case series with seven years follow-up.

BACKGROUND: The osteoarthritis of the ankle, although less common than other joints, is associated with severe functional limitation. Surgical options are ankle arthroscopic debridement, osteotomies, ankle arthrodesis and ankle arthroplasty. Ankle arthroplasty is increasingly used thanks to the new implants design, but ankle arthrodesis still represents the most used technique and it can be performed arthroscopically or with an open procedure. AIM: To compare mid-term results of arthroscopic vs open ankle arthrodesis of patients affected by end-stage ankle arthritis. METHODS: This study enrolled 23 patients, which underwent ankle arthrodesis. The patients were divided into 2 groups: group A (open procedure; n = 11) and group B (arthroscopic procedure, n = 12), the two groups were homogeneous with regard to age and body mass index (P = 0.347). The American Orthopaedic Foot and Ankle score (AOFAS), Freiburg Ankle score (FAS) and visual analogue scale for pain intensity were evaluated preoperatively, at six months and at final follow-up of 7.6 years in group A and 7.3 years in group B (P = 0.364). RESULTS: Patients in the arthroscopic group showed better results at six-month follow-up compared to the open group at the AOFAS (group A, 62.2; group B, 78.5; P < 0.05) and the FAS (group A, 61.1; group B, 70.3; P = 0.015) scores. Pain relief was achieved in both groups at six-month follow-up (group A, 1.4; group B, 0.9; P = 0.162). Both open and arthroscopic groups showed improved clinical outcomes from baseline to final follow-up (P > 0.05). Hospital stay was shorter in group B than in group A (P = 0.001). More complications were reported in the open group than in the arthroscopic group (P = 0.459). CONCLUSION: The arthroscopic and the open arthrodesis are valid and safe options for the treatment of ankle arthritis on the basis of clinical outcomes at 7 years follow-up. Moreover, the arthroscopic treatment shows faster improvement at six-month follow-up in comparison with the open group.

In vivo Histological Examination of the Graft Site 3 Years after Open-wedge High Tibial Osteotomy with Nanohydroxyapatite Augmentation.

Introduction: The open-wedge high tibial osteotomy (OWHTO) is a common technique for the treatment of medial compartmental osteoarthritis of the knee. There are many options to fill the osteotomy site gap. The autologous graft donor site morbidity can be avoided using heterologous bone grafts which represent a valid alternative. Case Presentation: This case report is about a 52-year-old male with knee osteoarthritis and varus deformity. Due to stiffness, swelling, and painful limitation during daily life activities, the patient underwent OWHTO. The osteotomy gap was filled with an equine cancellous bone wedge and nanohydroxyapatite (NHA) bone paste augmentation. After 3 years, the OWTHO was converted to total knee arthroplasty and a bone biopsy of the previous graft site was performed. The histological examination presented non-viable bone areas surrounded by viable bone without inflammatory cells, suggesting the presence of residual non-viable bone from the bone substitute graft. Conclusion: The in vivo histology of the graft site after 3 years has shown that heterologous bone is a safe and valid choice as a scaffold for bone regeneration. Augmentation with NHA bone paste achieved good osteoinduction without an inflammatory reaction and good integration of the bone substitute insert.

Donorsite defect of medial femoral condyle corticoperiostal flap in the treatment of lower limb infected nonunions.

BACKGROUNDS: Chronic osteomyelitis is a major challenge in orthopaedic surgery; it is the result of open fracture, periprosthetic infection and septic arthritis. Osteomyelitis leads to fracture nonunion. The treatment of bone infection and infected nonunion consists primarily of the complete removal of infected and avascular bone and soft tissue from the surgical site, followed by local and systemic pathogen-specific antibiotic therapy and temporary stabilisation, but may lead to massive skeletal and soft tissue defects. The use of free or pedicled vascularised bone transfers and callus distraction techniques (bone transport) has been recommended for large bone defects. The aim of this study is to evaluate the results of patients affected by infected non-unions of the lower limbs, treated with a corticoperiosteal flap from the medial femoral condyle and to investigate the donor site morbidity of this flap. MATERIALS AND METHODS: The patients were 11 males (average age of 45.6 years), who presented a nonunion of the tibial diaphysis in 7 cases and non-union of femoral diaphysis in 4 cases, treated with free or pedicled corticoperiosteal flap. In all patients, surgical debridement was performed before the flap of infected bone and soft tissues that would not contribute to wound healing. Clinical and radiographic evaluations of the recipient site were performed. Preoperative and postoperative X-ray and MRI scans after the 3-year follow-up of the donor site were performed, in order to observe possible bone restoration and any complications. RESULTS: The patients reported complete clinical and radiographic bone healing in 90.9 % of cases. As regards donor site, there were no differences between the medial femoral donor condyle compared to the contralateral site, due to complete regeneration of donor site bone. MRI investigation showed complete restoration of the donor site with vascularised bone in all patients. CONCLUSIONS: Our results suggest that the use of bone flaps for the treatment of infected non-unions is an effective procedure, that must be performed after accurate debridement of the non-union site. The corticoperiosteal flap seems to have few morbidities on the donor site and a high percentage of successful bone healing.

Mid-term CT assessment of bone healing after nanohydroxyapatite augmentation in open-wedge high tibial osteotomy.

BACKGROUND: The aim of the present study was to confirm the effectiveness of adding nanohydroxyapatite (NHA) to a heterologous bone graft in open-wedge high tibial osteotomy (OWHTO) by measuring the bone density via multislice computed tomography (CT) of the tibial osteotomy gap in a mid-term follow-up (five years). METHODS: Twenty-six patients undergoing OWHTO were randomly assigned to two groups: a pure graft group (Group A), in which the osteotomy gap was filled with only heterologous bone graft, and an NHA group (Group B), in which the osteotomy gap was filled with heterologous bone graft and NHA. CT was performed within one week of the operation, after two months, after 12 months and after five years. CT volume acquired in Hounsfield units (HU) was measured on three planes. RESULTS: The normal bone density was 110.2 ± 11.7 HU. The value of mean density at five years in Group A was 296.8 ± 81.8 HU, while in Group B, it was 202.2 ± 45.1 HU, showing a density more similar to normal bone and greater bone uniformity inside the osteotomy. The difference between the two groups was statistically significant (p < 0.05). Furthermore, both groups showed excellent mid-term clinical outcomes without significant differences. CONCLUSIONS: This study revealed that absorbability and bone formation at the osteotomy site in the NHA group was significantly higher as compared with the pure graft group at five years postoperatively.

Humeral shaft non-union in the elderly: Results with cortical graft plus stem cells.

INTRODUCTION: Humeral shaft is a common site of fracture non-union. Biology and bone quality represent some of the problems that the orthopaedic surgeon has to face up in the elderly. The goals of treatment of humeral shaft non-union are the achievement of mechanical stability and creation of a favourable biologic environment. Bone graft and stem cells are some of the augmentation techniques available to reach these goals. PURPOSE: Evaluation of the outcomes of humeral shaft non-union in elderly population treated with cortical allograft and stem cells. MATERIAL AND METHODS: A cohort of 21 patients with humeral shaft non-union was reviewed. Inclusion criteria were patients aged more than 65 years, with a diagnosis of humeral shaft non-union treated with cortical allograft and stem cells. Primary endpoints were 'bone healing' and 'time-to-union'. Secondary endpoints were shoulder and elbow function and patients' quality of life with Oxford Shoulder Score (OSS), Constant score and EuroQol-5D (EQ-5D). RESULTS: 6 patients met the inclusion criteria. In 5 of them, the cortical allograft was opposite to a plate, whereas in the other one a "Sandwich" technique was chosen because of large osteolysis. 'Bone healing' occurred in all patients after a mean of 3.3 months (range 2-5). In all but two patients, the elbow range of motion was in almost normal range (15-130). The mean OSS was 35.8 (+/- 6.4), whereas the mean Constant was 53.3 (+/- 2.2). The mean EQ-5D index was 0.451 (+/- 0.21). DISCUSSION: Bone healing occurred in all patients, with a time-to-union comparable or even better compared with other series. The use of cortical bone graft provide both stability and biological benefit, whereas stem cells improve the non-union environmental biology. Functional outcomes were lower than other series and patients' quality of life was similar to Italian elderly women. CONCLUSION: The use cortical allograft with stem cells is a viable strategy to treat humeral shaft non-union in the elderly.

Tibial internal rotation negatively affects clinical outcomes in total knee arthroplasty: a systematic review.

PURPOSE: The aim of this systematic review is to analyze the effect of tibial rotational alignment after total knee arthroplasty (TKA) on clinical outcomes and assess the eventual cut-off values for tibial TKA rotation leading to poor outcomes. METHODS: A detailed and systematic search from 1997 to 2017 of the Pubmed, Medline, Cochrane Reviews, and the Google Scholar databases was performed using the keyword terms "total knee arthroplasty", "total knee replacement", "tibial alignment", "tibial malalignement", "tibial rotation", "rotational error", "axis", "angle", "tibial malrotation", "clinical outcome", in several combinations. The modified Coleman scoring methodology (mCMS) was used. All the primary TKAs studies analyzing correlation between clinical results and tibial rotation were included. RESULTS: Five articles met the inclusion criteria. A total of 333 arthroplasties were included in this review; 139 had tibial component malalignment, while 194 were in control groups. The mean age of patients was 67.3 (SD 0.57) years. The mean average postoperative follow-up delay was 34.7 months (range 21-70). The mean mCMS score was 59.2 points indicating good methodological quality in the included studies. Functional outcomes were assessed through KSS, OKS, KOOS and VAS, negatively related to tibial internal rotation. CONCLUSIONS: Our review confirmed that excessive internal rotation of the tibial TKA component represents a significant risk factor for pain and inferior functional outcomes after TKA (> 10° of internal rotation demonstrated the common value), since external rotation does not affect the results. However, a universal precise cut-off value has not been found in the available literature and there remains a debate about CT rotation assessment and surgical intra-operative landmarks. LEVEL OF EVIDENCE: III.

Anatomic Double-Bundle Medial Patellofemoral Ligament Reconstruction with Autologous Semitendinosus: Aperture Fixation Both at the Femur and the Patella.

Medial patellofemoral ligament (MPFL) represents the main restraint against lateral patellar displacement. The MPFL insertion at the patella is up to 30 mm wide and is located along the upper half of the medial patellar rim. The femoral insertion of the MPFL is approximately 10 mm distal to the apex of the adductor tubercle and 16 mm proximal to the medial epicondyle. Since most of the patients suffer from MPFL rupture just after the first patellar dislocation, MPFL reconstruction results necessarily in all cases of chronic objective patellar instability to reestablish the primary passive patellofemoral stabilizer. Over time, different techniques of MPFL reconstruction have been proposed with promising results in terms of patient satisfaction and redislocation rate. However, each of these techniques may present peculiar problems and/or complications. An anatomic double-bundle MPFL reconstruction through an aperture fixation both at the femur and at the patella is here presented. The anatomic double-bundle MPFL reconstruction could allow recreating the fan-shape and biomechanics of original MPFL, whereas aperture fixation could provide a strong and safe fixation without risk of loosening or slackening of the graft.

Histiocitoma fibroso maligno do osso / Malignant fibrous histiocytoma of the bone

Apresentam-se quatro casos de histiocitoma fibroso maligno do osso atendidos no Hospital das Clínicas da UFMG, no período de janeiro de 1982 a dezembro de 1984. Fazem consideraçöes sobre as características clínicas e histológicas da doença e os métodos de tratamento. Chama-se a atençäo para a facilidade do diagnóstico histopatológico, para a alta incidência da recidiva no coto de amputaçäo, quando o tumor näo é ressecado com grande margem de segurança, e para efeito da quimioterapia na prevençäo das metástases subclínicas