ACL reconstruction using a quadruple semitendinosus graft with cortical fixations gives suitable isokinetic and clinical outcomes after 2 years.

PURPOSE: The objective of this single-center randomized single-blinded trial was to assess the hypothesis that anterior cruciate ligament reconstruction (ACLR) using a four-strand semitendinosus (ST) graft with adjustable femoral and tibial cortical fixation produced good outcomes compared to an ST/gracilis (ST/G) graft with femoral pin transfixation and tibial bioscrew fixation. Follow-up was 2 years. METHODS: Patients older than 16 years who underwent primary isolated ACLR included for 1 year until August 2017 were eligible. The primary outcome measures were the subjective International Knee Documentation Committee (IKDC) score, isokinetic muscle strength recovery, and return to work within 2 years. The study was approved by the ethics committee. RESULTS: Of 66 eligible patients, 60 completed the study and were included, 33 in the 4ST group and 27 in the ST/G group. Mean age was 30.5 ± 8.9 years in the 4ST group and 30.3 ± 8.5 in the ST/G group (n.s.). No significant between-group differences were found for mean postoperative subjective IKDC (4ST group, 80.2 ± 12.5; ST/G group, 83.6 ± 13.6; n.s.), side-to-side percentage deficits in isokinetic hamstring strength (at 60°/s: ST group, 17% ± 16%; ST/G group, 14% ± 11%; n.s.) or quadriceps strength (at 60°/s: ST group, 14% ± 12%; ST/G group, 19% ± 17%; n.s.), return to work, pain during physical activities, side-to-side differential laxity, balance, loss of flexion/extension, or surgical complications. CONCLUSION: This trial demonstrates that functional outcomes after 4ST for ACLR with cortical fixations could be as good, although not better, than those obtained using ST/G. The 4ST technique spares the gracilis tendon, which thus preserves the medial sided muscle and thereby could improve function and limit donor-side morbidity. LEVEL OF EVIDENCE: Level I.

Paradoxical adaptation of successful movements: The crucial role of internal error signals.

Visuo-motor adaptation has been classically studied using movements aimed at visual targets with visual feedback. In this type of experimental design, the respective roles of the different error signals cannot be fully disentangled. Here, we show that visuo-motor adaptation occurs despite the terminal success of the action and the compensation of the external error by a jump of the visual target. By using three grasping task conditions we manipulated the retinal error signal between the seen hand and the target (external error) and the conflict between the hand's visual reafference and either the proprioceptive or the efference copy signal (internal error), in order to estimate their respective roles in prism adaptation. In all conditions, subjects were asked to rapidly grasp an object. In the classical 'Prism' condition the object was stationary, which provided both external and internal errors. In the 'Prism & Jump' condition, at movement onset the object was suddenly displaced (jump) toward its virtual image location (visually displaced by the prism) which also corresponded to the location where the movement was planned to and executed through prisms. This jump therefore cancelled the external error (between the seen target and the seen hand), whereas the internal error (between the seen hand and the expected visual reafference of the hand, or between the seen hand and the hand felt by proprioception) was unchanged (because it is independent of the presence of the goal). In the 'Jump' condition, the movement was planned and executed without prismatic goggles and consequently with no internal error (no difference between where the hand visual reafference is expected to be and where it actually is), but the object was suddenly displaced at movement onset by a displacement equivalent to a prism shift which provided an external error. The 'Prism' and 'Prism & Jump' conditions exhibited similar aftereffects, whereas no aftereffect was observed in the 'Jump' condition. These results suggest that successful actions can be subjected to adaptation and that internal error is the only signal necessary to elicit true visuomotor adaptation characterized by context-independent generalization.

Feeling without localizing: exploring tactile misperception in a patient with uncommon parietal left brain damage.

Introduction: We report a very unique clinical presentation of a patient who complained, after a left parietal brain damage, about feeling tactile stimulations on his right upper limb without being able to localize them. Methods: Using a single case study approach, we report three experiments relying on several custom-made tasks to explore the different levels of somatosensory information processing, ranging from somato-sensation to somato-representation. Results: Our results showed a preserved ability to localize tactile stimuli applied on the right upper limb when using pointing responses while the ability to localize was less efficient when having to name the stimulated part (akin Numbsense). When the stimuli were applied on more distal locations (i.e., on the hand and on fingers), the number of correct responses decreased significantly independently of the modality of response. Finally, when visually presented with a stimulus delivered on the hand of an examiner in synchrony with the stimulation on the hidden hand of the patient, responses were largely influenced by the visual information available. Altogether, the convergence of these different customized tasks revealed an absence of autotopagnosia for motor responses for the right upper limb, associated with altered abilities to discriminate stimulus applied on distal and restricted/closer zones in the hand. Discussion: The somato-representation of our patient seemed to significantly rely on visual information, leading to striking deficits to localize tactile stimuli when vision and somesthesic afferences are discordant. This case report offers a clinical illustration of pathological imbalance between vision and somesthesia. Implications of these troubles in somato-representation on higher cognitive level processes are discussed.

Prisms adaptation improves haptic object discrimination in hemispatial neglect.

Neglect manifestations are typically explored in the visual modality. Although they are less commonly investigated tactile deficits also exist, and the aim of this study was to explore neglect in this modality. A haptic object discrimination task was designed to assess whether or not shape perception is impaired in seven right brain damaged patients with or without neglect. Each patient's performance on the object discrimination task was assessed before and after a brief period of prism adaptation, a bottom-up rehabilitation technique known to improve neglect symptoms. The results suggest that a haptic deficit - in the form of substantially more left errors - is present only in patients with neglect. Following prism adaptation, the left bias error rates in neglect patients were substantially reduced, and were similar to those observed in patients without neglect. Moreover, the haptic processing of the right side of objects also improved slightly. This finding suggests an expansion of the effects of prism adaptation to the unexposed, tactile modality supporting the cross-modal central effect hypothesis.