Prediction equations for permanent impairment of the upper extremity due to the loss of range of motion

Abstract

BACKGROUND:

Musculoskeletal disorders of the upper extremity are one of the major causes of human suffering, increased workers’ compensation expenses, and lost work time, productivity and quality at workplaces. In the developed countries, in case of permanent impairment, a rating is required by legal institutions in order to determine the compensation level. In addition, knowledge of the impairments is a valid reason for companies to take action in order to prevent the advancement and occurrence of the impairments in the future.

OBJECTIVE:

Developing impairment prediction models of the upper extremity due to the loss of range of motion of the wrist, forearm/elbow and shoulder joints.

METHODS:

The relationships between the loss of range of motion and corresponding impairment ratings of upper extremity joints were investigated by the least squares line fitting approach based on the available impairment data.

RESULTS:

Fourteen impairment prediction models due to the loss of range of motion of wrist, forearm/elbow and shoulder joints were developed. Most of the developed prediction models were linear models and several of them were 2nd and 3rd degree polynomial models. The models, overall, had relatively high predictive capabilities (for 10 of the 14 models: R²_adj>0.95; and for the remaining four models: 0.815 ≤ R²_adj ≤ 0.93).

CONCLUSIONS:

The developed equations automated by a simple code or a spreadsheet can easily be used for the evaluation of permanent upper extremity impairment and its effect on permanent impairment of the whole body by physicians, occupational therapists, ergonomists, insurance companies and legal institutions.