Ergonomic positioning or equipment for carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a condition where the median nerve, one of two main nerves to the hand, is compressed at the wrist, leading to pain in the hand, wrist and sometimes arm, and numbness and tingling especially in the thumb, index and middle finger. Weakness of the thumb muscles can also occur in severe cases. It affects approximately three per cent of the population, more commonly women.

Surgical treatment for CTS involves opening the carpal tunnel, the tunnel in which the median nerve passes through the wrist. Non-surgical treatments include medications, exercises, splinting and ergonomic interventions. Ergonomic interventions, such as keyboard modification, allow the hand to be used while the wrist is positioned in a straight position (neither flexed, extended or deviated to either side). In this straight (or neutral) wrist position the tunnel through which the median nerve passes is at its most capacious. This position is expected theoretically to place the least pressure on the median nerve.

This review aimed to find out how effective ergonomic treatments were in treating CTS. Only two studies were found (involving 105 participants). Both were designed to minimise research biases, but neither was of high quality. Neither study assessed short-term overall improvement, adverse effects or need for surgery as outcomes. One small study (25 participants) found an ergonomic keyboard reduced pain after 12 weeks but the second study reported no difference in pain severity between the keyboard groups at six months. Neither study found improvements in hand function or signs of CTS by people using ergonomic computer keyboards more than those experienced by people using standard keyboards. Based on the two studies in this review, which represent all the available evidence of sufficient quality for inclusion, there is no strong evidence for or against the use of ergonomic keyboards for the treatment of CTS.

Authors' conclusions: 

There is insufficient evidence from randomised controlled trials to determine whether ergonomic positioning or equipment is beneficial or harmful for treating carpal tunnel syndrome.

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Background: 

Non-surgical treatment, including ergonomic positioning or equipment, are sometimes offered to people experiencing mild to moderate symptoms from carpal tunnel syndrome (CTS). The effectiveness and duration of benefit from ergonomic positioning or equipment interventions for treating CTS are unknown.

Objectives: 

To assess the effects of ergonomic positioning or equipment compared with no treatment, a placebo or another non-surgical intervention in people with CTS.

Search strategy: 

We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 2, in The Cochrane Library), MEDLINE (1966 to June 2011), EMBASE (1980 to June 2011), CINAHL Plus (1937 to June 2011), and AMED (1985 to June 2011). We also reviewed the reference lists of randomised or quasi-randomised trials identified from the electronic search.

Selection criteria: 

Randomised or quasi-randomised controlled trials comparing ergonomic positioning or equipment with no treatment, placebo or another non-surgical intervention in people with CTS.

Data collection and analysis: 

Two review authors independently selected trials for inclusion, extracted data and assessed risk of bias of included studies. We calculated risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI) for the primary and secondary outcomes. We pooled results of clinically and statistically homogeneous trials, where possible, to provide estimates of the effect of ergonomic positioning or equipment.

Main results: 

We included two trials (105 participants) comparing ergonomic versus placebo keyboards. Neither trial assessed the primary outcome (short-term overall improvement) or adverse effects of interventions. In one small trial (25 participants) an ergonomic keyboard significantly reduced pain after 12 weeks (MD -2.40; 95% CI -4.45 to -0.35) but not six weeks (MD -0.20; 95% CI -1.51 to 1.11). In this same study, there was no difference between ergonomic and standard keyboards in hand function at six or 12 weeks or palm-wrist sensory latency at 12 weeks. The second trial (80 participants) reported no significant difference in pain severity after six months when using either of the three ergonomic keyboards versus a standard keyboard. No trials comparing (i) ergonomic positioning or equipment with no treatment, (ii) ergonomic positioning or equipment with another non-surgical treatment, or (iii) different ergonomic positioning or equipment regimes, were found.

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