[Testing of pronation and supination strength in the outpatient setting: a preliminary study]

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.

A New Wrist Clinical Evaluation Score

Background  The number of available wrist scoring systems is limited; some of them do not include forearm rotation criteria. Purpose  To describe a new electronic wrist clinical score and to present a new patient's generated wrist evaluation criterion, the subjective wrist value (SWV). Materials and Methods  A new electronic wrist clinical score, the Lyon wrist score (LWS) including wrist VAS pain and function, active range of motion and strength was built into an excel file. VAS flexion-extension pain and function were evaluated independently from pronation-supination pain and function. A new patient's generated wrist evaluation criterion, SWV was described. Results  The LWS is available in two versions, standard and full (the latter including forearm rotation strength). Both standard and full LWS are displayed into an automatically generated diamond-shaped graph providing a comprehensive visual display of the clinical status of most osteoarticular wrist disorders. The graph also includes SWV. The LWS, combined with SWV into a graph that may be directly exported to a PowerPoint presentation, provide a new practical and comprehensive tool for following/comparing wrist osteoarticular clinical status/outcomes. Both standard and full LWS charts are available in colored versions on a related website for free download. Conclusion  A comprehensive updated electronic display of osteoarticular wrist clinical status including forearm rotation criteria is provided and displayed into a graph which may be exported as such into a PowerPoint presentation for clinical analysis/comparisons. Level of Evidence  Level II.

[Is there any correlation between the strength of pronation and supination of the dominant hand and that of the non-dominant one in right-handed healthy adults: preliminary results]

We searched the existence of a link between the strength of pronation and supination of the dominant forearm and those of the non-dominant one. Ninety-seven volunteers were tested in pronation and supination with an analog dynamometer. Gender, age, dominance, height and weight were recorded. The measurement position was: 90° of elbow flexion, 0° of shoulder abduction, wrist slightly extended and neutral pronation-supination. We took four measurements per patient: strength in pronation and supination, in both the dominant and non-dominant sides. Fifteen subjects were evaluated twice. The left-handed (4) were removed from the statistical analysis. There were 38 men (37 years, 18-66) and 55 women (45 years, 21-71). Torques were higher (P<0.05) in men than in women, higher in supination than in pronation and in the dominant side compared to the non-dominant one (average ratio "non-dominant/dominant": 0.85; σ=0.16). There was a strong correlation between non-dominant hand strength and dominant hand strength (Pearson>0.6). Relating to the 15 subjects evaluated twice, the value of the forces varied during the day, but the ratio "non-dominant/dominant" was constant. The left-handed people were excluded, their values may be different from those of right-handers, as has been shown for grip strength. There was a strength variation during the day, but the ratio "non-dominant/dominant" was constant, making it more relevant intra-individual comparison (non-dominant side versus dominant side) rather inter-individual (based on charts of gender, age, weight and height). In the right-handed, the ratio "strength non-dominant side/dominant" is constant, defining easily in consultation the expected value of recovery of an injured forearm.

Dorsally displaced distal radius fractures treated by fixed-angle volar plating: Grip and pronosupination strength recovery. A prospective study

INTRODUCTION

Malunion following open reduction and internal fixation of distal radius fracture threatens wrist function. Fixed-angle palmar plates provide rigid fixation that is stable over time; however, the pronator quadratus sectioning required by the anterior approach entails a risk of pronation strength loss and of distal radioulnar joint destabilization. The present study assessed recovery of grip, pronation and supination strength following such internal fixation.

PATIENTS AND METHOD

A prospective study included 26 distal radial fractures with dorsal displacement, osteosynthesized using a fixed-angle palmar plate, in 25 patients (mean age: 47.5 years; range: 17-72 years). Assessment concerned the classical parameters, plus grip and pronosupination strength recovery.

RESULTS

At a mean 14 months follow-up (range: 6-30 months), patients had recovered 91% grip strength, 88% pronation strength and 85% supination strength with respect to the healthy side. Complications comprised three cases of malunion, two of reflex sympathetic dystrophy syndrome, and four of post-traumatic carpal tunnel syndrome.

DISCUSSION

A study of the literature found 75-95% grip strength recovery following osteosynthesis using fixed-angle plates. Few studies, however, have focused on pronosupination strength, and none reported its evolution following osteosynthesis.

CONCLUSION

The present study found no drawbacks associated with a technique which usually involves sectioning the pronator quadratus. Except in case of malunion or joint stiffness, fixed-angle palmar plate osteosynthesis was followed by recovery of grip and pronosupination strength.

LEVEL OF EVIDENCE

Level IV: prospective non-randomized, non-comparative observational study.

Transverse loaded pronosupination test

A new test to evaluate the ability of the distal radioulnar joint to sustain transverse loads while the forearm rotates from pronation to supination is described. Both arms were tested in 100 normal volunteers. The average weight-bearing capability of the normal unsupported forearm was 5.07 kg, equating to a force of 49.8 N. The test may be useful in the assessment of pathological conditions involving weakness of the forearm rotator muscles, with or without joint incongruity, as well as being an indirect way to assess the load-bearing capacity of radioulnar implants.