A comparative study of clinical muscle testing and Cybex evaluation after shoulder operations

One hundred consecutive patients treated with shoulder surgery were studied to determine their functional recovery. Their average age was 47.3 years, and the average follow-up period was ten months. Clinical grading of muscle strength was compared pre- and postoperatively with objective testing using the Cybex II Isokinetic System, with subjective functional assessment by dictation, and with the ability of the patient to return to work. The clinical grade of muscle strength increased postoperatively by approximately one-half of a grade in both forward flexion and external rotation. However, various Cybex parameters did not significantly improve. The postoperative values were significantly less for the operated side than for the uninvolved side. Only weak statistical correlations were found between the clinical muscle grading and objective Cybex evaluation. Pain relief was obtained in 87% of the patients. Eighty-six percent of the patients returned to work, although 43% returned to light duty only. Thirty-two percent of patients reported full recovery, while 58% had decreased but satisfactory function. The study showed that although the clinical assessment of muscle strength improved early after shoulder surgery, the clinical grading of muscle power did not correlate well with objective parameters of strength, endurance, ability to work, or functional assessment. Strength did not recover to the level of the uninvolved opposite shoulder. Endurance, which is not measured by clinical grading, may decrease. Longer follow-up and rehabilitation periods are required to optimize results.