Wheelchair ergonomic hand drive mechanism use improves wrist mechanics associated with carpal tunnel syndrome

Reinventing the wheel for a manual wheelchair

PURPOSE

Standard manual wheelchairs (MWCs) are inefficient and pushrim propulsion may cause progressive damage and pain to the user's arms. We describe a wheel for a MWC with a novel propulsion mechanism.

METHODS

The wheel has two modes of operation called "Standard" mode and "Run" mode. In Run mode, the wheelchair is propelled forward by pushing a compliant handle forward and then pulling it back, both strokes contributing to forward propulsion. We report the propulsive force and preliminary testing on a rough outdoor circuit by three able-bodied participants.

RESULTS

In Run mode, the peak applied force is reduced to 30% and the maximum force gradient is reduced to 10% of that for standard pushrim propulsion, for the same work output. The travel time for the 1.06 km outdoor circuit is about 60% of that for a brisk walk and about 40% of that for pushrim propulsion. At a propulsion speed of 1 m/s, the cardiovascular effort in Run mode is 56% of that for pushrim propulsion. Automatic hill-hold in Run mode improves safety when ascending slopes. The mechanism has three gears so that it can be used by people with widely varying strength and fitness. Folding the handle away converts the operation to Standard mode with the conventional pushrim propulsion, supplemented by three gears.

CONCLUSIONS

Despite the increased weight, width and friction, the bimodal geared wheels facilitate wheelchair travel on challenging paths. This may bring significant improvement to the quality of life of MWC users.

Surgical intervention for carpal tunnel syndrome in individuals with spinal cord injuries-patient characteristics, diagnostic considerations, and treatment outcomes

STUDY DESIGN

A retrospective chart audit.

OBJECTIVES

To characterize SCI patients with carpal tunnel syndrome (CTS) and evaluate the diagnostic rationale for surgical decision-making.

SETTING

Swiss Paraplegic Centre, Nottwil, Switzerland.

METHODS

Retrospective investigation of medical history, diagnostics, surgeries, and outcomes of surgical treatments of CTS in patients with para- and tetraplegia.

RESULTS

We identified a total of 77 surgeries for CTS in 55 patients: 16 females (25 surgeries) and 39 males (52 surgeries) with spinal cord injury. The majority (47 persons, 68 surgeries) were paraplegic (level of lesion Th2 and below); 8 persons (9 surgeries) were tetraplegic (level of lesion Th1 and above). ASIA scores in the tetraplegic group were A: 0, B: 1, C: 4, D: 3 while complete lesions predominated in the paraplegic group (A: 32, B: 4, C: 5, D: 6). Sixty-six out of 77 patients reported total relief of symptoms. Neither nerve conduction velocity nor motor amplitude correlated well with the severity of CTS. Co-morbidity and specific risk factors were rare.

CONCLUSIONS

SCI patients with CTS respond well to surgical decompression of median nerve regardless of level and type of spinal cord lesion and risk factors. Nerve conduction parameters and clinical findings can provide additional diagnostic support of CTS although nocturnal hand paresthesia, wrist pain at and after loading as well as failed conservative treatment are the main indications for surgical interventions. Based on symptomatology, clinical findings, and nerve conduction studies, we propose a decision-making tree for suggesting surgery or not.

Physiological parameters depending on two different types of manual wheelchair propulsion

OBJECTIVE

The purpose of this study was to compare aerobic parameters in the multistage field test (MFT) in hand rim wheelchair propulsion and lever wheelchair propulsion.

METHODS

Twenty-one men performed MFT using two different types of propulsion, i.e., lever and hand rim wheelchair propulsion. The covered distance and physiological variables (oxygen uptake (VO₂), minute ventilation (VE), carbon dioxide output (VCO₂), respiratory coefficient (RQ), and heart rate (HR)) were observed. Physiological variables were measured with Cosmed K5 system. Kolmogorov-Smirnov test, t-test, Wilcoxon test and effect sizes (ESs) were used to assess differences. Statistical significance was set at p < .05.

RESULTS

A significantly longer distance was observed in lever wheelchair propulsion than in hand rim wheelchair propulsion (1,194 and 649 m, respectively). VO_2max and RQ were higher in hand rim wheelchair propulsion. All physiological variables for the last (fifth) level of the test in hand rim propulsion were significantly higher than in lever wheelchair propulsion. ES was large for each observed difference.

CONCLUSION

The lever wheelchair propulsion movement is less demanding than hand rim wheelchair propulsion and longer distances can be achieved by the user. There is a need to check lever wheelchair propulsion in different types of field tests.

Case-Control Study of Ultrasound Evaluation of Acute Median Nerve Response to Upper Extremity Circuit Training in Spinal Cord Injury

OBJECTIVE

Individuals with spinal cord injury (SCI) often present signs and symptoms of median nerve (MN) pathology. Preclinical signs identification of MN pathology might facilitate early intervention to prevent or delay carpal tunnel syndrome in SCI. We assessed if ultrasound parameters changed in response to upper extremity (UE) circuit training exercise in individuals with paraplegia and able-bodied individuals.

DESIGN

Case-control study.

PARTICIPANTS

Adults (N=32) with paraplegia (n=16) and age- and sex-matched able-bodied controls (n=16).

INTERVENTION

Circuit training exercise.

MAIN OUTCOME MEASURES

MN ultrasound evaluation at the pisiform and radius before and after UE exercise. Ultrasound parameters included cross-sectional area (CSA), and gray scale (GS). Data presented as mean ± SD.

RESULTS

Pre-exercise CSAs were larger in SCI at the radius (12.0±2.9 vs 9.0±2.1; P=.003), but not the pisiform (9.8±3.1 vs 9.1±1.7; P=.431). There were no statistical differences in MN response to exercise between groups (all P≥.293). Across participants, CSA changes were inversely associated with their pre-exercise values at the pisiform (r=-0.648; P<.001) and the radius (r=-0.366; P=.043). Participants with pre-exercise CSA values ≥10.00 mm² at the pisiform responded to exercise with decreases in CSA (mean change ± SD, -2.0±1.5; P=.002) and GS (-2.8±6.2; P=.029). Participants with pre-exercise CSA ≤9.99 mm² at the pisiform responded to exercise with no change in CSA (mean change ± SD, 0.7±2.5; P=.002) and increased GS (3.2±7.2; P=.029).

CONCLUSIONS

CSA exercise response was more strongly related to pre-exercise MN values than presence or absence of SCI.

The effect of wheelchair propulsion style on changes in time spent in extreme wrist orientations after a bout of fatiguing propulsion

This study compared how wheelchair propulsion styles affect changes in percentage of time spent in extreme wrist orientations, which have been associated with median nerve injury, after a fatiguing bout of propulsion. Twenty novice, non-disabled adult males learned arcing (ARC) and semicircular (SEMI) propulsion styles and utilised each to perform a wheelchair fatigue protocol. ARC and SEMI did not significantly differ in terms of changes after the fatigue protocol in percentage of time spent in extreme flexion/extension or radial/ulnar deviation at the push phase beginning or end. A pattern was observed, although not significant, of greater increases in percentage of time spent in extreme wrist extension and ulnar deviation during the push phase beginning and ulnar deviation during the push phase end while utilising SEMI relative to ARC. This study evinces that individual differences are greater than observed changes in extreme wrist orientations for both propulsion styles. Practitioner Summary: How wheelchair propulsion styles change with fatigue in terms of extreme wrist orientations was examined. This study evinces that individual differences are greater than observed changes in extreme wrist orientations for both propulsion styles and point towards the need for future research on individual differences utilising propulsion styles.