Determining Validity of Measures of Pain and Perceived Effort of Women With Hand Osteoarthritis During a Jar Opening Task

Abstract

Purpose: Joint protection strategies are often recommended for individuals with hand arthritis. However, there is little research regarding their effectiveness or on the use of self-report measures in evaluating the effects of joint protection strategies. The purpose of this study was to examine the relationship between the self-report measures of pain and perceived exertion and actual hand forces used during the everyday task of opening a sealed jar in order to validate their use in measuring the effectiveness of joint protection strategies such as using a counterforce such as a table or opposing extremity and using a nonskid material. A secondary purpose was to evaluate the effects of the type of grasp, the hand grasping the lid, and the use of non-skid material on the hand forces acting upon ajar lid when breaking a jar's seal. Methods: A novel jar device created by McGee, Nuckley, and Mathiowetz1 was used to gather measurements of grip force, compressive force down through the lid's axis of rotation (Fz), shear force tangential to the lid (Fy), and compressive force perpendicular to the side of the lid (Fx) (Figure 1a) when attempting to open a 'sealed jar'. The jar lid's torque requirement was set to 4.24 Nm, a torque commonly imposed by the manufacturer when creating a seal on larger diameter jars. Thirty-one women with hand osteo-arthritis were asked to complete 16 jar opening simulations by alternating three different factors: hand turning the jar lid, position (supinated/vertical and power/diagonal), and use of a non-skid material (Figure 1b). After each jar turning simulation, participants were asked to report their perceived level of pain and exertion using the 0 to 10 scales of the NRS and Borg CRIO, respectively. Results: The impact of arthritis on our sample's function was modest (AIMS2-SF2 Total Health Score x = 10.62) and the distribution of arthritis between hands was not dissimilar (Table 1). Descriptive data is presented in Figures 1c and id. A significant, Distribution of hand arthritis Joint Distribution Avg # digits involved Right 2.09, Left 2.03 1st CMC (90%) Bilateral 23/31 (74%) Unilateral 5/31 (16%) (4R, 1L) Wrist level (TriScaph) (16%) Bilateral 2/31 (6.5%) Unilateral 3/31(9.5%) (2R, 1L) Other Digits RIF (39%), RLF (35%), LIF (39%), LLF (33%) positive relationship was found between pain, as measured by the NRS, and the actual hand forces utilized while opening a sealed jar (2.2>(3 >18.8, p > .03). A more significant and positive relationship was found between perceived effort and hand force/time (1.4>p >59.0, p>.001). Use of the supinated grasp required less force/time in Fx [F(1,419) = 30.5, p < .0001 ], Fy [F(1,419) = 34.5, < .0001]. Participants used less grip force to twist the lid with their left hand than with their right hand [F(l,419) = 21.7, p < .0001 ] (Figure 2a). Participants also perceived their effort to be less when using their left hand, a supinated grasp, and non-skid material {Figure 2b). Additionally, participants rated their pain as lower when using their left hand and when using a supinated grasp (Figure 2c). Lastly, a left supinated grasp with a non-skid material was a significantly more successful strategy to open jars than was any other (χ² = 9.4, p < .001). The NRS and Borg CRIO appear to be measuring different constructs and not the just effect of pain on exertion [r² = .09, F(1,110) = 11.1, p < .001] across both hands. Conclusion: The present study has helped to validate the use of the Borg CR10 and NRS scales as effective tools for predicting force reduction when opening a sealed jar. Thus, both would appear to be appropriate direct measures of the presumed force-reducing benefit of joint protection training. For example, a one point reduction of perceived effort per the Borg CR10 corresponds with a reduction of 59N per second while opening a sealed jar. The counterforce offered by the supinated 'stabilizing' hand results in the use of fewer compressive and sheer forces by the turning hand. The left hand requires less grip force to successfully open a sealed jar and pain as well as perceived effort were least among those who used a non-skid material when opening. This data supports that women with hand arthritis will know more success, perceive less pain and effort, use less grip force, and will more efficiently generate the forces required to break the seal of a large jar when using a left hand, supinated counterforce, and non-skid material. Further research is needed to determine 1) how much force generation is required to be successful in ajar turning task and 2) how other factors such as hand mobility, wrist strength, hand sensibility, and maximum grip strength predict success.