Testing grip strength is a popular assessment used by occupational therapists in a range of clinical settings. It is fast, easy to perform, reliable and produces a result which is simple to record. Results of grip strength testing have been used to determine a baseline measure of performance against which change can be compared, as well as comparison of results to normative data. This article reviews the literature associated with the measurement of grip strength. It addresses the purposes of grip strength measurement; the instruments used and their reliability and accuracy; the testing position and protocol suggested for use and aspects of these which may influence results; the use of normative data and factors which influence grip strength, including age, gender and occupation; and various methods to determine level or sincerity of effort. Recommendations are made regarding these issues to enable clinicians to conduct grip strength assessments and interpret the results with confidence.

Handgrip strength testing: A review of the literature

We studied normal hand strength and the difference between dominant and nondominant hands. Two hundred fourteen volunteers were tested with a calibrated Jamar dynamometer at all five levels. A pinch gauge was used to assess key and pulp pinch. Height, weight, sex, hand dominance, and hobby demands were predictive of maximum grip. Mean maximum grip for women was 81 lb. and for men was 137 lb. Key pinch averaged 22%, while pulp pinch averaged 16% of maximum grip. Only 129 (60%) patients had maximum strengths at level 2. The majority of right-handed subjects were 10% stronger in grip strength on the dominant side. In left-handed subjects, mean grip was the same for both hands; the nondominant hand was stronger in 50% of left-handed subjects.

Hand strength: normative values.

The reliability of the grip force instrument, Grippit was tested on 51 right-handed women of which 18 were healthy, 19 had rheumatoid arthritis (RA) and 14 had fibromyalgia (FM). Normative data was obtained from 169 healthy subjects. Results indicate that the reliability of Grippit was high in healthy and rheumatoid arthritic women and satisfactory in women with fibromyalgia. All patients showed greatly reduced grip force (RA had on average 21% and FM 40% of the control values) when compared to healthy women. Healthy women had on average 54% of men's grip force. The ratio between average force over 10 seconds and peak force was 73% for RA women, 69% for FM women, 83% for healthy women and 85% for healthy men.

Grip force in patients with rheumatoid arthritis and fibromyalgia and in healthy subjects. A study with the grippit instrument

Aim of the study: Reliable and valid evaluation of hand strength is important for determining the effectivity of treatment strategies and it is accepted that grip and pinch strength provide an objective index for the functional integrity of upper extremity. This study was designed to evaluate the grip and pinch strength differences between sides for the right and left handed population. Methods: The study included 128 right and 21 left hand dominant volunteers. Grip strength of the participants were measured by using a Jamar dynamometer. Pulp pinch strength measurements were performed by manual pinchmeter. Results: When the study group was totally evaluated, a statistically significant difference was found between the grip and pinch strengths of dominant and nondominant hands in favour of the dominant hand. For further information we grouped 149 participants as right and left handed and investigated the number of subjects with stronger nondominant hand for each group. The percentage of stronger nondominant hand grip was 10.93% and 33.33% for right and left handed groups respectively. The results were less significant for pinch strength with 28.12% and 28.57% for right and left handed subjects respectively. Conclusion: We concluded that the dominant hand is significantly stronger in right handed subjects but no such significant difference between sides could be documented for left handed people.

Grip strength: effect of hand dominance.

BACKGROUND: The best treatment for an inadequately reduced fracture of the distal part of the radius is not well established. We collected prospective outcomes data for patients undergoing open reduction and internal fixation of an inadequately reduced distal radial fracture with use of the volar locking plating system.

METHODS: Over a two-year period, 161 patients underwent open reduction and internal fixation of an inadequately reduced distal radial fracture with use of the volar locking plating system. Patients were enrolled in the present study three months after the fracture on the basis of strict entry criteria and were evaluated three, six, and twelve months after surgery. Outcome measures included radiographic parameters, grip strength, lateral pinch strength, the Jebsen-Taylor test, wrist range of motion, and the Michigan Hand Outcomes Questionnaire.

RESULTS: Eighty-seven patients with a distal radial fracture were enrolled. The mean age at the time of enrollment was 48.9 years. Forty percent (thirty-five) of the eighty-seven fractures were classified as AO type A, 9% (eight) were classified as type B, and 51% (forty-four) were classified as type C. Radiographic assessment showed that the plating system maintained anatomic reduction at the follow-up periods. At the time of the twelve-month follow-up, the mean grip strength on the injured side was worse than that on the contralateral side (18 compared with 21 kg; p < 0.01), the mean pinch strength on the injured side was not significantly different from that on the contralateral side (8.7 compared with 8.9 kg; p = 0.27), and the mean flexion of the wrist on the injured side was 86% of that on the contralateral side. All Michigan Hand Outcomes Questionnaire domains approached normal scores at six months, with small continued improvement to one year.

CONCLUSIONS: The volar locking plating system appears to provide effective fixation when used for the treatment of initially inadequately reduced distal radial fractures.

LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

ORIGINAL ABSTRACT CITATION: “Treatment of Unstable Distal Radial Fractures with the Volar Locking Plating System” (2006;88:2687-94).

Treatment of Unstable Distal Radial Fractures with the Volar Locking Plating System

The purpose of this study was to test the utility of the 10% rule in hand rehabilitation. The 10% rule states that the dominant hand possesses a 10% greater grip strength than the nondominant hand. This rule has been used for many years to assist therapists in setting strength goals for patients with injured hands. The sample for this study consisted of 310 male and female students, faculty, and staff from a small, private liberal arts college located in Pennsylvania. Grip strength was measured with a factory-calibrated Jamar dynamometer. Results showed an overall 10.74% grip strength difference between dominant and nondominant hands. This finding verified the 10% rule. However, when the data were separated into left-handed and right-handed subjects, a 12.72% difference for right-handed subjects and a -0.08% difference for left-handed subjects was found. In conclusion, this study showed that the 10% rule is valid for right-handed persons only; for left-handed persons, grip strength should be considered equivalent in both hands.

Deborah Conklin

Papers

Grip strength and hand dominance: challenging the 10% rule.