A standard method of shoulder strength measurement for the Constant score with a spring balance

The strength component of the Constant score has been criticized for its lack of a precisely defined measurement method. A series of experiments was performed to compare three different methods in normal and pathologic shoulders with the use of a standard test position. These were (1) the Isobex isometric dynamometer, (2) Constantʹs unsecured spring balance, and (3) a new modification in which the spring balance is fixed at one end and the reading is taken after 5 seconds of maximum effort. The results suggest that this simple modification with a low-cost spring balance can give similar values to those from the Isobex. The need for precision of terms and a definition of the method is discussed, and recommendations for the standardization of the many variables in making this measurement are made. (J Shoulder Elbow Surg 1998;7:116-21.)