Section 17I. (a) The commission shall provide coverage for prosthetic devices and repairs to any active or retired employee of the commonwealth who is insured under the group insurance commission under the same terms and conditions that apply to other durable medical equipment covered under the policy, except as otherwise provided in this section.

(b) In this section, ''prosthetic device'' shall mean an artificial limb device to replace, in whole or in part, an arm or leg.

(c) Such coverage shall not impose any annual or lifetime dollar maximum on coverage for prosthetic devices other than an annual or lifetime dollar maximum that applies in the aggregate to all items and services covered under the policy.

(d) Such coverage shall not apply amounts paid for prosthetic devices to any annual or lifetime dollar maximum applicable to other durable medical equipment covered under the policy other than an annual or lifetime dollar maximum that applies in the aggregate to all items and services covered under the policy.

(e) Such coverage may include a reasonable coinsurance requirement for prosthetic devices and repairs, not to exceed 20 per cent of the allowable cost of the prosthetic device or repair, unless all covered benefits applying coinsurance under the plan do so at a higher amount. If the policy provides coverage for services from nonparticipating providers, the policy may include a reasonable coinsurance requirement for prosthetic devices and repairs, not to exceed 40 per cent of the allowable cost of the device or repair when obtained from a nonparticipating provider, unless all covered benefits applying coinsurance under the plan do so at a higher amount.

(f) Such coverage may require prior authorization as a condition of coverage for prosthetic devices.