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Hand-held dynamometry in patients with haematological malignancies: measurement error in the clinical assessment of knee extension strength.

Knols RH, Aufdemkampe G, de Bruin ED, Uebelhart D, Aaronson NK - BMC Musculoskelet Disord (2009)

Bottom Line: The SDDs for the generated parameters varied from 17.23 Nm (11.04% of GM) to 27.26 Nm (17.09% of GM) for intra-observer measurements, and 26.76 Nm (16.77% of GM) to 31.62 Nm (18.66% of GM) for inter-observer measurements, with similar results for the limits of agreement.The results indicate that there is acceptable relative reliability for evaluating knee strength with a HHD, while the measurement error observed was modest.The HHD may be useful in detecting changes in knee extension strength at the individual patient level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Rheumatology and Institute of Physical Medicine, University Hospital Zurich, Switzerland. ruud.knols@usz.ch

ABSTRACT

Background: Hand-held dynamometry is a portable and inexpensive method to quantify muscle strength. To determine if muscle strength has changed, an examiner must know what part of the difference between a patient's pre-treatment and post-treatment measurements is attributable to real change, and what part is due to measurement error. This study aimed to determine the relative and absolute reliability of intra and inter-observer strength measurements with a hand-held dynamometer (HHD).

Methods: Two observers performed maximum voluntary peak torque measurements (MVPT) for isometric knee extension in 24 patients with haematological malignancies. For each patient, the measurements were carried out on the same day. The main outcome measures were the intraclass correlation coefficient (ICC +/- 95%CI), the standard error of measurement (SEM), the smallest detectable difference (SDD), the relative values as % of the grand mean of the SEM and SDD, and the limits of agreement for the intra- and inter-observer '3 repetition average' and the 'highest value of 3 MVPT' knee extension strength measures.

Results: The intra-observer ICCs were 0.94 for the average of 3 MVPT (95%CI: 0.86-0.97) and 0.86 for the highest value of 3 MVPT (95%CI: 0.71-0.94). The ICCs for the inter-observer measurements were 0.89 for the average of 3 MVPT (95%CI: 0.75-0.95) and 0.77 for the highest value of 3 MVPT (95%CI: 0.54-0.90). The SEMs for the intra-observer measurements were 6.22 Nm (3.98% of the grand mean (GM) and 9.83 Nm (5.88% of GM). For the inter-observer measurements, the SEMs were 9.65 Nm (6.65% of GM) and 11.41 Nm (6.73% of GM). The SDDs for the generated parameters varied from 17.23 Nm (11.04% of GM) to 27.26 Nm (17.09% of GM) for intra-observer measurements, and 26.76 Nm (16.77% of GM) to 31.62 Nm (18.66% of GM) for inter-observer measurements, with similar results for the limits of agreement.

Conclusion: The results indicate that there is acceptable relative reliability for evaluating knee strength with a HHD, while the measurement error observed was modest. The HHD may be useful in detecting changes in knee extension strength at the individual patient level.

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Standardization of measurements. Performance of a maximum voluntary peak torque assessment at a knee angle of 25° of flexion. Standard body position of the patient and the device are shown. The patient stabilized the trunk by grasping the table.
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Figure 1: Standardization of measurements. Performance of a maximum voluntary peak torque assessment at a knee angle of 25° of flexion. Standard body position of the patient and the device are shown. The patient stabilized the trunk by grasping the table.

Mentions: The MVPT for knee extension was tested at a knee angle of 25 degrees [33]. An angle of 25 degrees was selected to correspond to the knee angle at which the force production is of crucial importance in walking, as has been shown in biomechanical analyses of this activity [33,40,41]. Patients were positioned sitting upright, with no back support, and with the hips in 90 degrees flexion. The patient stabilized the trunk by grasping the table. The thigh of the patient was stabilized by the examiner's hand. Thus, the examiner assured that sufficient counterforce was produced by the thigh, so that the lower limb could not pivot down during the break test with the knee near full extension. In this way, the examiner could ensure that the knee extension was really "broken". The joint angles were defined according to the Academy of Orthopaedic Surgeons (AAOS) system [42]. The HHD was positioned perpendicular to the tibia, at 80% of the shank length (between the marks at the lower edge of the 'lateral epicondylus' and the lower edge of the 'lateral malleolus'), distal to the knee. The knee joint centre and the 80% shank length were marked with a dot on the patients' skin. The position of the patient, the examiner, and the HHD were standardized (Figure 1).


Hand-held dynamometry in patients with haematological malignancies: measurement error in the clinical assessment of knee extension strength.

Knols RH, Aufdemkampe G, de Bruin ED, Uebelhart D, Aaronson NK - BMC Musculoskelet Disord (2009)

Standardization of measurements. Performance of a maximum voluntary peak torque assessment at a knee angle of 25° of flexion. Standard body position of the patient and the device are shown. The patient stabilized the trunk by grasping the table.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2662793&req=5

Figure 1: Standardization of measurements. Performance of a maximum voluntary peak torque assessment at a knee angle of 25° of flexion. Standard body position of the patient and the device are shown. The patient stabilized the trunk by grasping the table.
Mentions: The MVPT for knee extension was tested at a knee angle of 25 degrees [33]. An angle of 25 degrees was selected to correspond to the knee angle at which the force production is of crucial importance in walking, as has been shown in biomechanical analyses of this activity [33,40,41]. Patients were positioned sitting upright, with no back support, and with the hips in 90 degrees flexion. The patient stabilized the trunk by grasping the table. The thigh of the patient was stabilized by the examiner's hand. Thus, the examiner assured that sufficient counterforce was produced by the thigh, so that the lower limb could not pivot down during the break test with the knee near full extension. In this way, the examiner could ensure that the knee extension was really "broken". The joint angles were defined according to the Academy of Orthopaedic Surgeons (AAOS) system [42]. The HHD was positioned perpendicular to the tibia, at 80% of the shank length (between the marks at the lower edge of the 'lateral epicondylus' and the lower edge of the 'lateral malleolus'), distal to the knee. The knee joint centre and the 80% shank length were marked with a dot on the patients' skin. The position of the patient, the examiner, and the HHD were standardized (Figure 1).

Bottom Line: The SDDs for the generated parameters varied from 17.23 Nm (11.04% of GM) to 27.26 Nm (17.09% of GM) for intra-observer measurements, and 26.76 Nm (16.77% of GM) to 31.62 Nm (18.66% of GM) for inter-observer measurements, with similar results for the limits of agreement.The results indicate that there is acceptable relative reliability for evaluating knee strength with a HHD, while the measurement error observed was modest.The HHD may be useful in detecting changes in knee extension strength at the individual patient level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Rheumatology and Institute of Physical Medicine, University Hospital Zurich, Switzerland. ruud.knols@usz.ch

ABSTRACT

Background: Hand-held dynamometry is a portable and inexpensive method to quantify muscle strength. To determine if muscle strength has changed, an examiner must know what part of the difference between a patient's pre-treatment and post-treatment measurements is attributable to real change, and what part is due to measurement error. This study aimed to determine the relative and absolute reliability of intra and inter-observer strength measurements with a hand-held dynamometer (HHD).

Methods: Two observers performed maximum voluntary peak torque measurements (MVPT) for isometric knee extension in 24 patients with haematological malignancies. For each patient, the measurements were carried out on the same day. The main outcome measures were the intraclass correlation coefficient (ICC +/- 95%CI), the standard error of measurement (SEM), the smallest detectable difference (SDD), the relative values as % of the grand mean of the SEM and SDD, and the limits of agreement for the intra- and inter-observer '3 repetition average' and the 'highest value of 3 MVPT' knee extension strength measures.

Results: The intra-observer ICCs were 0.94 for the average of 3 MVPT (95%CI: 0.86-0.97) and 0.86 for the highest value of 3 MVPT (95%CI: 0.71-0.94). The ICCs for the inter-observer measurements were 0.89 for the average of 3 MVPT (95%CI: 0.75-0.95) and 0.77 for the highest value of 3 MVPT (95%CI: 0.54-0.90). The SEMs for the intra-observer measurements were 6.22 Nm (3.98% of the grand mean (GM) and 9.83 Nm (5.88% of GM). For the inter-observer measurements, the SEMs were 9.65 Nm (6.65% of GM) and 11.41 Nm (6.73% of GM). The SDDs for the generated parameters varied from 17.23 Nm (11.04% of GM) to 27.26 Nm (17.09% of GM) for intra-observer measurements, and 26.76 Nm (16.77% of GM) to 31.62 Nm (18.66% of GM) for inter-observer measurements, with similar results for the limits of agreement.

Conclusion: The results indicate that there is acceptable relative reliability for evaluating knee strength with a HHD, while the measurement error observed was modest. The HHD may be useful in detecting changes in knee extension strength at the individual patient level.

Show MeSH
Related in: MedlinePlus