(1)
In any case in which an employee having an existing permanent partial disability suffers injury, the employer shall provide compensation for such disability as is found to be attributable to that injury based upon the average weekly wages of the employee at the time of the injury. If following an injury falling within the provisions of subsection (c)(1)–(20) of this section, the employee is totally and permanently disabled, and the disability is found not to be due solely to that injury, the employer shall provide compensation for the applicable prescribed period of weeks provided for in that section for the subsequent injury, or for one hundred and four weeks, whichever is the greater, except that, in the case of an injury falling within the provisions of subsection (c)(13) of this section, the employer shall provide compensation for the lesser of such periods. In all other cases of total permanent disability or of death, found not to be due solely to that injury, of an employee having an existing permanent partial disability, the employer shall provide in addition to compensation under subsections (b) and (e) of this section, compensation payments or death benefits for one hundred and four weeks only. If following an injury falling within the provisions of subsection (c)(1)–(20) of this section, the employee has a permanent partial disability and the disability is found not to be due solely to that injury, and such disability is materially and substantially greater than that which would have resulted from the subsequent injury alone, the employer shall provide compensation for the applicable period of weeks provided for in that section for the subsequent injury, or for one hundred and four weeks, whichever is the greater, except that, in the case of an injury falling within the provisions of subsection (c)(13) of this section, the employer shall provide compensation for the lesser of such periods.
In all other cases in which the employee has a permanent partial disability, found not to be due solely to that injury, and such disability is materially and substantially greater than that which would have resulted from the subsequent injury alone, the employer shall provide in addition to compensation under subsections (b) and (e) of this section, compensation for one hundred and four weeks only.