Comparison of the effect of two application methods of self-adherent wrap (Coban™) on range of motion in the hands of healthy subjects

Introduction

If hand oedema is not successfully managed it can lead to the development of a variety of complications and ultimately loss of hand function. The application of compression therapy is a common modality used to control oedema. The aim of compression is to facilitate absorption of molecules by the venous and lymphatic systems ¹ and to increase tissue hydrostatic pressure to improve venous and lymphatic flow.

Coban™ is a self-adherent dressing used to create a compressive force for oedema control. ^2–4 In addition to decreasing oedema, further advantages of Coban™ are that it is self-adherent, secure, non-adherent to underlying tissues, protective, adaptable to any size hand and permits normal mobility and activity. ⁴

Although there are anecdotal care guides based on case reports ⁴ that describe the use of Coban™, there are no studies that have investigated its effects. There is also a lack of any evidence-based protocol for the application of Coban™. An unpublished study investigating the current practice of a sample of hand therapists revealed that the two most commonly used application techniques were spiral (67%) and cylindrical (21%). ⁵ However, there was no rationale for why each method was chosen.

Application of any dressings to the hand can potentially restrict range of motion (ROM). Therefore the use of modalities that are applied to produce compression not only need to be effective in oedema control/reduction but should also be applied in such a way that they produce the least restriction to joint motion. In fact the preservation of active motion will also aid oedema reduction.

Methods

The aim of this study was to investigate the effect of two application methods of Coban™ on hand ROM.

A within-subject design was used to evaluate 25 participants who were uninjured, healthy volunteers. This number of participants was not chosen based on statistical power but based on participant availability. Participants were recruited by advertising for volunteers at the University of Nottingham and within the Nottingham University Hospital NHS Trust. Exclusion criteria were previous hand trauma, any hand pathology, open wounds, skin rashes or previous experience of using Coban™. Written informed consent was obtained from each participant prior to the study. Ethical approval was given by the University of Nottingham Medical School Ethics Committee.

By conducting this study on healthy, uninjured participants, variance in trauma that would exist in a hand injured population was removed. Other variables such as pain, oedema and anxiety, which could also decrease ROM and compliance, were eliminated; therefore, the effect of Coban™ was investigated exclusively.

One physiotherapist applied both interventions. The cylindrical application method consisted of wrapping a rectangular piece of Coban™ around the length of the digit, securing it dorsally and trimming off the excess material.

The spiral application method consisted of spiralling a narrow piece of Coban™ from the distal tip of the digit down its length. An overlap of approximately half the width of the Coban™ was applied. The Coban™ was applied to the index finger, middle finger and thumb of the participant's dominant hand. The dominant hand of each participant was determined by a standard grasp response. This was performed by holding a pen directly in front of the participant and asking them to take it. The hand that they used to take the pen was deemed their dominant hand. Each type of Coban™ application was allocated randomly to minimize order effects. Active ROM was assessed by a student physiotherapist. Active range of joint flexion was measured in the index and middle fingers and the inter-phalangeal joint (IPJ) and metacarpophalangeal joint (MCPJ) of the thumb using a calibrated small joint goniometer (Mobilis Rolyan, Nottinghamshire, UK) placed on the dorsal aspect of the digits. The carpometacarpal joint (CMCJ) of the thumb was measured using the Kapandji scale. ⁶

In order to identify the most suitable analysis, a Shapiro–Wilk test of normality was used. Data from measurements of flexion at the IP and MCP joints contained a mixture of normally and non-normally distributed data and therefore were analysed using non-parametric tests. Friedman's two-way analysis of variance by ranks was used to analyse the data using SPSS (Statistical Package for the Social Sciences, version 19).

Results

Twenty-five participants volunteered and completed the study. Right-handed dominance represented 92% of the participant population.

Table 1 displays the change in range of flexion for each joint and opposition of the thumb CMC joint without Coban™, with spiral and cylindrical application of Coban™. All joints showed a decrease in ROM with the application of both cylindrical and spiral Coban™. The loss of flexion was greater with the spiral Coban™ application for all joints excluding the MCP joints of both the index and middle fingers, where the cylindrical application resulted in a greater loss of flexion.

There was a statistically significant decrease in flexion from baseline to spiral Coban™ application and from baseline to cylindrical Coban™ application for all joints excluding the MCPJ and CMCJ of the thumb.

There was a statistically significant difference in range of flexion between cylindrical and spiral Coban™ applications at the index finger proximal interphalangeal (PIP) joint, and the middle finger PIP and distal interphalangeal joints. Spiral application resulted in a greater decrease in flexion.

Discussion

In this study both methods of application of Coban™ reduced range of joint flexion. Restricting the movement of a joint with the application of Coban™ could have detrimental effects on reducing oedema as the extent of active exercise will be limited. As well as being applied directly over the skin, Coban™ is frequently applied over dressings ^2,4,7 that are often bulky, limiting the motion of the hand and making it less amenable to effective hand therapy. ⁸ In these cases where hand motion may already be compromised, the additional application of Coban™ must be carefully considered.

Although the results show a number of statistically significant differences in ROM between spiral and cylindrical application of Coban™, on more detailed inspection of these results it can be seen that the difference is no greater than 5° of motion. It is commonly accepted that due to measurement error a difference greater than 5° would need to be detected for it to be clinically important. ⁹ The results indicate that a cylindrical Coban™ application may be preferable as movement is restricted to a lesser extent.

During periods of immobilization, e.g. following skin grafts ^10,11 or fracture fixation, ¹² the nature of the Coban™ application and the amount of movement it allows is not relevant. In these situations the compression exerted by the Coban™ and its effect on oedema reduction is a more important goal.

The differences in pressure exerted by the different application techniques were not investigated in this study. However, verbal feedback from the participants indicated that greater pressure was perceived with the spiral application. If a spiral application was found to exert a greater pressure, it may be that it is more effective at reducing oedema. If this is the case, then the decrease in ROM and subsequent effect on hand function may be a sacrifice that the therapist is willing to make but this would need to be decided on a case by case basis.

This study has a number of limitations; one of these was the lack of blinding of the tester who could have been influenced by the knowledge of which Coban™ application was being assessed. A further limitation was that only the thumb, index and middle fingers were dressed in Coban™ as these digits are most commonly used in a functional ‘pinch’ action. Motion of the fourth and fifth fingers was not assessed.

Conclusions

The application of Coban™ to digits resulted in small but statistically significant changes in range of finger joint flexion. However the question remains over which application is more effective at reducing oedema and whether the extent of movement reduction is of clinical importance. Further research is needed to explore the effect of these two types of application in a hand injured population on oedema and digital flexion.