Hyaluronan (HA) is a high molecular weight glycosaminoglycan of the extracellular matrix (ECM), which is particularly abundant in soft connective tissues. Solutions of HA can be highly viscous with non-Newtonian flow properties. These properties affect the movement of HA-containing fluid layers within and underlying the deep fascia. Changes in the concentration, molecular weight, or even covalent modification of HA in inflammatory conditions, as well as changes in binding interactions with other macromolecules, can have dramatic effects on the sliding movement of fascia. The high molecular weight and the semi-flexible chain of HA are key factors leading to the high viscosity of dilute solutions, and real HA solutions show additional nonideality and greatly increased viscosity due to mutual macromolecular crowding. The shear rate dependence of the viscosity, and the viscoelasticity of HA solutions, depend on the relaxation time of the molecule, which in turn depends on the HA concentration and molecular weight. Temperature can also have an effect on these properties. High viscosity can additionally affect the lubricating function of HA solutions. Immobility can increase the concentration of HA, increase the viscosity, and reduce lubrication and gliding of the layers of connective tissue and muscle. Over time, these changes can alter both muscle structure and function. Inflammation can further increase the viscosity of HA-containing fluids if the HA is modified via covalent attachment of heavy chains derived from Inter-α-Inhibitor. Hyaluronidase hydrolyzes HA, thus reducing its molecular weight, lowering the viscosity of the extracellular matrix fluid and making outflow easier. It can also disrupt any aggregates or gel-like structures that result from HA being modified. Hyaluronidase is used medically primarily as a dispersion agent, but may also be useful in conditions where altered viscosity of the fascia is desired, such as in the treatment of muscle stiffness.

Synopsis Understanding upper limb impairment after stroke is essential to planning therapeutic efforts to restore function. However determining which upper limb impairment to treat and how is complex for two reasons: 1) the impairments are not static, i.e. as motor recovery proceeds, the type and nature of the impairments may change; therefore the treatment needs to evolve to target the impairment contributing to dysfunction at a given point in time. 2) multiple impairments may be present simultaneously, i.e., a patient may present with weakness of the arm and hand immediately after a stroke, which may not have resolved when spasticity sets in a few weeks or months later; hence there may be a layering of impairments over time making it difficult to decide what to treat first. The most useful way to understand how impairments contribute to upper limb dysfunction may be to examine them from the perspective of their functional consequences. There are three main functional consequences of impairments on upper limb function are: (1) learned nonuse, (2) learned bad-use, and (3) forgetting as determined by behavioral analysis of tasks. The impairments that contribute to each of these functional limitations are described.

We examined planning and execution of precision grasp in eight right-handed patients with a right pure motor or sensorimotor lacunar syndrome after a subcortical stroke and eight age-matched controls as they grasped and lifted an instrumented object whose weight could be varied without altering its visual appearance. Grip (normal) and load (tangential) forces at the fingertip-object interface were measured and the grip force rate (GFR) and load force rate (LFR) were derived. Planning of precision grasp was assessed by measurement of anticipatory scaling of peak GFR and peak LFR to object weight. Execution of precision grasp was assessed by measurement of both the timing and efficiency of grip-load force coordination: the pre-load phase duration (PLD) and the load phase duration (LPD) measured timing, whereas the grip force at load force onset (GFO) and the grip force at lift-off (GFL) measured efficiency. Subjects lifted a light and heavy object five times first with the RIGHT hand, then with the LEFT hand, and then once more with the RIGHT AFTER LEFT hand. Patients with stroke did not scale the peak LFR or peak GFR to object weight with the RIGHT hand even with repeated attempts; however, they scaled the peak LFR to object weight on the first lift with the RIGHT AFTER LEFT hand (P = 0.01). Patients also prolonged the PLD and LPD and produced excessive GFO and GFL for RIGHT hand lifts, but decreased the GFL for the heavy object (P = 0.016) with the RIGHT AFTER LEFT hand. Correlation of precision grasp variables from lifts with the RIGHT hand with clinical measures showed that anticipatory scaling of peak LFR and peak GFR did not correlate with clinical measures of hand function, whereas the PLD did (r = 0.88, P = 0.004). The results suggest that patients with right hemiparesis from a subcortical lesion of the corticospinal tract have a higher-order motor planning deficit. This planning deficit is dissociable from deficits in motor execution, is not captured by routine clinical assessment, and is correctable by transfer of information from the unaffected hemisphere. A rehabilitation strategy that involves practice with the left hand prior to practice with the right hand may improve planning of grasping behaviour in patients with right hemiparesis.

Efficient grasping requires planned and accurate coordination of finger movements to approximate the shape of an object before contact. In healthy subjects, hand shaping is known to occur early in reach under predominantly feedforward control. In patients with hemiparesis after stroke, execution of coordinated digit motion during grasping is impaired as a result of damage to the corticospinal tract. The question addressed here is whether patients with hemiparesis are able to compensate for their execution deficit with a qualitatively different grasp strategy that still allows them to differentiate hand posture to object shape. Subjects grasped a rectangular, concave, and convex object while wearing an instrumented glove. Reach-to-grasp was divided into three phases based on wrist kinematics: reach acceleration (reach onset to peak horizontal wrist velocity), reach deceleration (peak horizontal wrist velocity to reach offset), and grasp (reach offset to lift-off). Patients showed reduced finger abduction, proximal interphalangeal joint (PIP) flexion, and metacarpophalangeal joint (MCP) extension at object grasp across all three shapes compared with controls; however, they were able to partially differentiate hand posture for the convex and concave shapes using a compensatory strategy that involved increased MCP flexion rather than the PIP flexion seen in controls. Interestingly, shape-specific hand postures did not unfold initially during reach acceleration as seen in controls, but instead evolved later during reach deceleration, which suggests increased reliance on sensory feedback. These results indicate that kinematic analysis can identify and quantify within-limb compensatory motor control strategies after stroke. From a clinical perspective, quantitative study of compensation is important to better understand the process of recovery from brain injury. From a motor control perspective, compensation can be considered a model for how joint redundancy is exploited to accomplish the task goal through redistribution of work across effectors.

The nature of impairment in hand motor control after stroke and its relationship to hand function are still not well understood. In this study, we investigated digit independence in patients with subcortical stroke (n = 8) and moderate hand impairment, defined by wrist and hand Fugl-Meyer scale scores < or =25/33, and age-matched controls (n = 8). Subjects made cyclical flexion-extension movements of an instructed digit while keeping the other digits as still as possible. Movements of the metacarpo-phalangeal (MCP) joints of the five digits were measured using an instrumented glove. The ability to move an instructed digit individually (individuation index), and the ability to keep a noninstructed digit as still as possible (stationarity index) were determined for each digit. Contrary to the finding of normal thumb individuation in a recent study of patients with variable hand motor impairment after stroke, we found that independent movement for all digits was significantly impaired, although individuation and stationarity were differentially affected for each digit. All the digits, including the thumb, showed a similar impairment in individuation. In contrast, stationarity was affected in a digit-dependent pattern: the thumb was affected least, and the middle finger was most impaired. Stroke subjects did not extend their digits fully to the baseline position, and the angular displacement at maximum digit extension correlated significantly with digit individuation. Contrary to expectation, digit independence correlated weakly with clinical tests of hand function, which emphasize grasp. This suggests that corticospinal projections might be separated with respect to function rather than finger topography.

Robotic technology designed to assist rehabilitation can potentially increase the efficiency of and accessibility to therapy by assisting therapists to provide consistent training for extended periods of time, and collecting data to assess progress. Automatization of therapy may enable many patients to be treated simultaneously and possibly even remotely, in the comfort of their own homes, through telerehabilitation. The data collected can be used to objectively assess performance and document compliance as well as progress. All of these characteristics can make therapists more efficient in treating larger numbers of patients. Most importantly for the patient, it can increase access to therapy which is often in high demand and rationed severely in today’s fiscal climate. In recent years, many consumer grade low-cost and off-the-shelf devices have been adopted for use in therapy sessions and methods for increasing motivation and engagement have been integrated with them. This review paper outlines the effort devoted to the development and integration of robotic technology for rehabilitation.

Objective. Gait performance is an indicator of mobility impairment after stroke. This study evaluated changes in balance, lower extremity motor function, and spatiotemporal gait parameters after receiving body weight supported treadmill training (BWSTT) and conventional overground walking training (CT) in patients with subacute stroke using 3D motion analysis. Setting. Inpatient department of rehabilitation medicine at a university-affiliated hospital. Participants. 24 subjects with unilateral hemiplegia in the subacute stage were randomized to the BWSTT (n = 12) and CT (n = 12) groups. Parameters were compared between the two groups. Data from twelve age matched healthy subjects were recorded as reference. Interventions. Patients received gait training with BWSTT or CT for an average of 30 minutes/day, 5 days/week, for 3 weeks. Main Outcome Measures. Balance was measured by the Brunel balance assessment. Lower extremity motor function was evaluated by the Fugl-Meyer assessment scale. Kinematic data were collected and analyzed using a gait capture system before and after the interventions. Results. Both groups improved on balance and lower extremity motor function measures (P < 0.05), with no significant difference between the two groups after intervention. However, kinematic data were significantly improved (P < 0.05) after BWSTT but not after CT. Maximum hip extension and flexion angles were significantly improved (P < 0.05) for the BWSTT group during the stance and swing phases compared to baseline. Conclusion. In subacute patients with stroke, BWSTT can lead to improved gait quality when compared with conventional gait training. Both methods can improve balance and motor function.

Nearly one-quarter of participants had pressure sores at the time of the survey. Periodic weight lifts and daily inspection of skin for pressure damage were not associated with decreased prevalence of pressure sores in this sample. However, those who inspected skin daily tended to detect pressure damage early.