New Assessment of Forearm Strength: Reliability and Validity

Protocol for Forearm Pronosupination Strength Measuring in Different Postures: Reliability and Influence of Relevant Factors

IMPORTANCE

Despite the importance of pronosupination strength, which is key in daily activities, current evaluation protocols are disparate, and results differ regarding the influence of factors such as gender, age, limb dominance, or posture.

OBJECTIVE

To design a reliable device to measure pronation and supination torques in different forearm positions, considering the influence of gender, age, and limb dominance.

DESIGN

Reliability study with analysis of intrarater and interrater repeatability and examination of the influence of different factors on the strength of pronation and supination.

SETTING

Biomechanical analysis laboratory of the Instituto de Biomecánica de Valencia.

PARTICIPANTS

Convenience sample of 39 healthy male and female participants, ages 18 to 65 yr.

OUTCOMES AND MEASURES

Pronation strength and supination strength were studied in five forearm positions: 30° and 60° of supination, neutral rotation, and 30° and 60° of pronation. The influence of gender, age, and limb dominance was studied using repeated-measures analysis of variance. Intrarater and interrater reliabilities were studied in 17 participants, and the intraclass correlation coefficients (ICCs) were calculated from three measurement sessions.

RESULTS

Except for 60° of pronation, all ICCs ranged from .72 to .97. Gender, limb dominance, and posture significantly affected pronosupination strength (p < .05), with the highest supination strength at 60° of pronation and the highest pronation strength at 60° of supination.

CONCLUSIONS AND RELEVANCE

In using this reliable pronosupination torque assessment device and standardized protocol in the clinical setting, clinicians must consider the influence of gender, limb dominance, and forearm posture. What This Article Adds: The results of this study will allow occupational therapists to establish differences between patients' functionality in comparison with healthy individuals and to design recovery treatments and facilitate performance of manual tasks, considering which are the most advantageous positions to exert force. Furthermore, the developed device can be used to monitor the evolution of these torques in an objective and reliable manner.

Does access through the pronator quadratus influence pronation strength in palmar plate fixation of distal radius fractures in elderly patients?

INTRODUCTION

Palmar plate fixation of the distal radius fracture involves dissecting the pronator quadratus (PQ). This is regardless of whether the approach is radial or ulnar to the flexor carpi radialis (FCR) tendon. It is not yet clear whether and to what extent this dissection leads to a functional loss of pronation or pronation strength. The aim of this study was to investigate the functional recovery of pronation and pronation strength after dissection of the PQ without suturing.

MATERIALS AND METHODS

From October 2010 to November 2011, patients aged over 65 with fracture were prospectively enrolled in this study. Fracture stabilisation was performed via the FCR approach without suturing the PQ. Follow-up examinations took place 8 weeks and 12 months postoperatively, and pronation and supination strength were analysed by means of an especially developed measuring device.

RESULTS

212 patients were initially screened and 107 were enrolled. The range of motion compared to the healthy opposite side was Ext/Flex 75/66% 8 weeks postoperatively. Pronation was 97% with a pronation strength of 59%. After 1 year, the scores improved to Ext/Flex 83/80%. Pronation recovered to 99% and pronation strength to 78%.

CONCLUSION

The present study can show a recovery of pronation as well as pronation strength in a large patient population. At the same time, the pronation strength is still significantly lower 1 year after the operation than on the opposing healthy side. As the pronation strength recovers as the grip strength and is at all times on a par with the supination strength, we believe that we can continue to refrain from re-fixating the pronator quadratus.

Validity and reliability of a portable handheld dynamometer compared to a fixed isokinetic dynamometer to assess forearm torque strength

To evaluate the effect of treatment on forearm rotation, torque muscle strength can be assessed using an isokinetic device (IKD) or a wrist dynamometer (WD). The aims of this study were 1) to determine concurrent validity and intra- and inter-rater reliability using the WD, and to examine correlations between WD and IKD in different positions; and 2) subsequently, to establish the intermethod reproducibility between WD as a handheld (HHD) or fixed device. We conducted a cross-sectional study in which torque strength was measured in healthy participants by two observers using an IKD and a WD. Study endpoints were concurrent validity (Pearson's r), intra- and inter-rater reliability, intermethod reproducibility (intraclass correlation coefficient: ICC) and measurement error (limits of agreement: LoA). Concurrent validity ranged, in the 2 studies assessing it, from r 0.37 to 0.52 for pronation and from r 0.50 to 0.82 for supination, with wide 95% confidence intervals. ICC for intra-rater reliability for pronation ranged from 0.85 to 0.91 and for supination from 0.91 to 0.95. ICC for inter-rater reliability for pronation ranged from 0.84 to 0.96 and for supination from 0.92 to 0.96. Despite the excellent intra- and inter-rater reliability and intermethod reproducibility for the WD-HHD and fixed WD, validity was low when compared to IKD and wide LoA indicated a high measurement error of approximately 20%. These results suggest that the WD cannot replace the IKD isometric mode for pronation and supination. LEVEL OF EVIDENCE: 2.

Intrarater reliability test of the ISOmetric power device-A new instrument for assessment of isometric force in six directions of wrist motion

STUDY DESIGN

Descriptive reliability study.

INTRODUCTION

A well-functioning wrist requires sufficient range of motion accompanied by adequate strength in every movement and direction-factors that are not regularly measured simultaneously in patients with wrist problems today. The ISOmetric Power device (ISOP) is a new instrument that measures isometric wrist force in all six directions of motion, but its intrarater reliability in a healthy population has not yet been evaluated.

PURPOSE OF THE STUDY

The purpose of this study was to perform an intrarater reliability test of the ISOP in healthy participants.

METHODS

Thirty-two healthy study participants (16 women/16 men; mean age 38.3 years; SD 6.5) were included. With a standardized testing protocol, the three planes of wrist motion- wrist flexion/extension, radial/ulnar deviation, pro/supination-were measured at one time interval (T1) and repeated after one week (T2). The results were analyzed using the intraclass correlation coefficient (ICC). A paired-samples t-test was also performed to determine if a statistically significant difference (P < .05) existed between the first and the second test values. Measurements with Jamar Dynamometer were performed at both time intervals, for internal control of measurement intrarater reliability.

RESULTS

Excellent correlations (ICC: 0.90-0.99) were found for all test-retests performed. The lowest value (ICC: 0.90) was seen for supination and the highest value (ICC: 0.99) for flexion of the left hand. No statistically significant differences were found in any of the pairs (P > .05) in terms of test-re-test, which additionally strengthen the correlation between the first and second test values.

DISCUSSION

Contrary to the Jamar Dynamometer, the ISOP is not designed for measuring grip strength, but for assessing the isometric muscle force in flexion, extension, pronation, supination, and radial and ulnar deviation. A systematic review has reported a moderate to strong correlation between isometric strength and dynamic performances. Thus, the ISOP is a more complete and applicable instrument for evaluating the functional strength in different directions in the upper extremity.

CONCLUSIONS

The ISOmetric Power device shows excellent intrarater reliability and is proposed to be a possible valuable wrist strength assessment tool to aid in both diagnostics and outcome measures of wrist and upper extremity disorders.

Comparison of maximal isometric forearm supination torque in two elbow positions between subjects with and without limited forearm supination range of motion

Study Design: Cross-sectional comparison. Introduction: Forearm supination range of motion is often limited by short or stiff pronators. Many studies have examined maximal isometric forearm supination torque (MIFST). However, there is little research comparing MIFST in two elbow positions between subjects with and without limited forearm supination range of motion (LSR). Purpose of the Study: The purpose of this study was to compare MIFST in two elbow positions (90º flexed elbow, extended elbow) between subjects with and without LSR. Methods: Thirteen right-handed subjects (seven men, six women) with LSR and 13 age- and gender-matched healthy controls participated in this study. The forearm supination range of motion and MIFST were measured using a Smart KEMA system. Two-way repeated-measures analysis of variance was used to compare MIFST in two elbow positions between subjects with and without LSR. Results: No significant difference between groups (p > .05) was found. However, there was an interaction effect between elbow position and group on MIFST (p < .05). Independent t-tests were used to confirm the simple effects. In the LSR group, the value of MIFST was significantly lower in the elbow-extended position than in the group without LSR (p < .05). Conclusions: These findings indicate that elbow position should be considered when assessing the strength or increasing the strength of the supinator muscle, especially in patients with LSR.

New Methods to Assess Forearm Torque and Lifting Strength: Reliability and Validity

PURPOSE

To determine the repeatability and validity of new methods designed to objectively measure forearm torque and lifting strength in a clinical setting.

METHODS

Twenty-eight healthy volunteers, 19 women and 9 men, were tested for lifting strength and forearm torque with the Kern and Baseline dynamometers. Two raters tested each participant on 3 occasions in the standing position. One of the raters also examined 15 subjects, 3 times, for forearm torque in the seated position and for lifting strength and forearm torque by the Work Simulator II, Baltimore Therapeutic Equipment (BTE II). Intraclass correlation coefficients (ICC) model 2,1 was used to calculate ICCs for intra- and interrater reliability. The same ICC model and Bland-Altman plots were used to analyze the validity and agreement between the new test methods and the BTE II equipment and for comparison between tests performed in the standing and seated positions.

RESULTS

Intra- and interrater reliability for forearm torque measurements with both the Baseline and the BTE II demonstrated ICCs between 0.88 and 0.96. The comparison between the Baseline and the BTE equipment yielded lower ICCs of 0.74 to 0.88 but they were still substantial and in good agreement. The ICCs for torques recorded in the standing and seated position were 0.89 to 0.96. Lifting strength, measured in 3 different positions of forearm rotation, yielded ICC values between 0.84 and 0.96 for both raters and with both the Kern and the BTE II instruments. Similarly, comparisons between the Kern and the BTE II methods showed ICC values between 0.91 and 0.95.

CONCLUSIONS

Both the Baseline and the Kern dynamometers demonstrated excellent intra- and interrater repeatability. Except for forearm torque test in direction of pronation, which had a slightly lower ICC of 0.74, our new methods were valid when the BTE II was used as the reference standard. Assessments in the standing or seated position for torque measurements made little difference. Thus, we found the quality of measurements performed with our new methods sufficient for future studies of forearm torque and lifting strength.

CLINICAL RELEVANCE

Simple, yet reliable, methods to quantify torque and lifting strength in a clinical setting have the potential to improve evaluations of wrist and forearm disorders as well as their treatments.

Forearm Torque and Lifting Strength: Normative Data

PURPOSE

To establish reference values for new methods designed to quantitatively measure forearm torque and lifting strength and to compare these values with grip strength.

METHODS

A total of 499 volunteers, 262 males and 237 females, aged 15 to 85 (mean, 44) years, were tested for lifting strength and forearm torque with the Kern and Baseline dynamometers. These individuals were also tested for grip strength with a Jamar dynamometer. Standardized procedures were used and information about sex, height, weight, hand dominance, and whether their work involved high or low manual strain was collected.

RESULTS

Men had approximately 70% higher forearm torque and lifting strength compared with females. Male subjects aged 26 to 35 years and female subjects aged 36 to 45 years showed highest strength values. In patients with dominant right side, 61% to 78% had a higher or equal strength on this side in the different tests performed. In patients with dominant left side, the corresponding proportions varied between 41% and 65%. There was a high correlation between grip strength and forearm torque and lifting strength. Sex, body height, body weight, and age showed a significant correlation to the strength measurements. In a multiple regression model sex, age (entered as linear and squared) could explain 51% to 63% of the total variances of forearm torque strength and 30% to 36% of lifting strength.

CONCLUSIONS

Reference values for lifting strength and forearm torque to be used in clinical practice were acquired. Grip strength has a high correlation to forearm torque and lifting strength. Sex, age, and height can be used to predict forearm torque and lifting strength. Prediction equations using these variables were generated.

CLINICAL RELEVANCE

Normative data of forearm torque and lifting strength might improve the quality of assessment of wrist and forearm disorders as well as their treatments.

Normative values of isometric elbow strength in healthy adults: a systematic review

BACKGROUND

Post-traumatic deformities such as biceps tendon rupture or (peri-)articular fractures of the elbow are often related to a decrease in muscle strength. Postoperative evaluation of these deformities requires normative values of elbow strength. The purpose of this systematic review was to determine these normative values of isometric elbow strength in healthy adults resulting from studies evaluating this strength (i.e. flexion, extension, pronation and supination strength).

METHODS

The databases of PubMed, EMBASE and Web of Sciences were searched and screened for studies involving the isometric elbow strength as measured in asymptomatic volunteers. The quality of the studies was assessed and studies of low quality were excluded.

RESULTS

Nineteen studies met the inclusion criteria and were of sufficiently high quality to be included in the present review. In these studies, elbow strength was measured in a total of 1880 healthy volunteers. The experimental set-up and devices used to measure elbow strength varied between studies. Using some assumptions, a normative values table was assembled.

CONCLUSIONS

Large standard deviations of normative values in combination with different measurement devices used, as well as the different measurement positions of the subjects, demonstrated that there is no consensus about measuring the isometric elbow strength and therefore the normative values have to be interpreted with caution.

Elbow flexion and forearm supination strength in a healthy population

BACKGROUND AND HYPOTHESIS

Despite the lack of representative data of a healthy population, many clinical trials concerning the measurement of postoperative elbow flexion or forearm supination strength use the contralateral side as a control. We hypothesized that there are no differences in elbow flexion and supination strength between the dominant and nondominant sides in healthy volunteers.

METHODS

The study was performed on a cross-sectional cohort of healthy subjects without any prior injuries or surgical interventions of the upper extremities. Isometric elbow flexion strength and supination strength were measured on both the dominant and nondominant sides. The results were analyzed for the entire group and subanalyzed for female vs. male, for different age groups, and according to handedness and regular practice of overhead sports.

RESULTS

A total of 150 subjects (75 female and 75 male subjects; mean age, 44 ± 15 years [range, 18-72 years]) were included in this study. Within the entire collective, no significant differences concerning the elbow flexion strength between the dominant and nondominant sides could be detected, whereas the supination strength was 7% higher on the dominant side (P = .010). Women, right-hand-dominant subjects, and subjects who do not regularly practice overhead sports have a significant 8% higher supination strength on the dominant side compared with the nondominant side (P < .05). Left-hand-dominant subjects have an 8% higher elbow flexion strength on the nondominant right side (P < .05).

CONCLUSION

Elbow flexion strength and forearm supination strength differ between the dominant and nondominant sides. The contralateral upper extremity cannot be used as a matched control without some adjustments.

Supination and Pronation Strength Deficits Persist at 2-4 Years after Treatment of Distal Radius Fractures

Forearm rotation is a key function in the upper extremity. Following distal radius fracture, residual disability may occur in tasks requiring forearm rotation. The objectives of this study are to define pronation and supination strength profiles tested through the range of forearm rotation in normal individuals, and to evaluate the rotational strength profiles and rotational strength deficits across the testing range in a cohort of patients treated for distal radius fracture associated with an ulnar styloid base fracture. In a normative cohort of 29 subjects the supination strength profile showed an increasing linear relationship from supination to pronation. Twelve subjects were evaluated 2-4 years after anatomical open reduction and volar plate fixation of a distal radius fracture. The injured wrist was consistently weaker (corrected for hand dominance) in both supination and pronation strength in all testing positions, with the greatest loss in 60 degrees supination. Mean supination strength loss across all testing positions was significantly correlated with worse PRWE scores, highlighting the importance of supination in wrist function.

Systematic Review of Studies on Measurement Properties of Instruments for Adults Published in the American Journal of Occupational Therapy, 2009–2013

OBJECTIVE. We describe the methodological quality of recent studies on instrument development and testing published in the American Journal of Occupational Therapy (AJOT).

METHOD. We conducted a systematic review using the COnsensus-based Standards for the selection of health status Measurement INstruments (COSMIN) checklist to appraise 48 articles on measurement properties of assessments for adults published in AJOT between 2009 and 2013.

RESULTS. Most studies had adequate methodological quality in design and statistical analysis. Common methodological limitations included that methods used to examine internal consistency were not consistently linked to the theoretical constructs underpinning assessments; participants in some test–retest reliability studies were not stable during the interim period; and in several studies of reliability and convergent validity, sample sizes were inadequate.

CONCLUSION. AJOT’s dissemination of psychometric research evidence has made important contributions to moving the profession toward the American Occupational Therapy Association’s Centennial Vision. This study’s results provide a benchmark by which to evaluate future accomplishments.

The effect of a Galeazzi fracture on the strength of pronation and supination two years after surgical treatment

The aim of this study was to determine the effect of a Galeazzi fracture on the strength of pronation and supination at a mean of two years after surgical treatment. The strength of pronation and supination was measured in varying rotational positions of the forearm of ten male patients (mean age 38.9 years (21 to 64)) who had undergone plate fixation for a Galeazzi fracture. The stability of the distal radioulnar joint was assessed, and a clinical assessment using the quick-Disabilities of the Arm Shoulder and Hand (quickDASH) questionnaire and patient-related wrist examination (PRWE) scores was undertaken. In addition, the strength of pronation and supination was measured in a male control group of 42 healthy volunteers (mean age 21.8 years (18 to 37)).

The mean absolute loss of strength of supination in the injured compared with the non-injured arm throughout all ranges of forearm rotation was 16.1 kg (sem 5.3), corresponding to a relative loss of 12.5% (95% confidence interval (CI) 3.6 to 21.4). For the strength of pronation, the mean loss was 19.1 kg (sem 4.5), corresponding to a relative loss of 27.2% (95% CI 14.2 to 40.1). Loss of strength of supination following a Galeazzi fracture correlated with poor quickDASH (p = 0.03) and PRWE scores (p < 0.01).

Loss of strength of pronation (27.2%), and of supination (12.5%) in particular, after a Galeazzi fracture is associated with worse clinical scores, highlighting the importance of supination of the forearm in function of the upper limb.

Cite this article: Bone Joint J 2013;95-B:1508–13.