¶1One who is entitled to compensation under the workmen’s compensation act, G. L. c. 152, cannot claim compensation for existing disability or suffering which can be lessened by resort to the reasonable remedies and operations of the medical and surgical practice of the time and place if these are not attended with serious risk to life or member and if the outcome reasonably to be expected is beneficial. The test is not his willingness to submit to operation, but his right to guard fife and limb from unreasonable peril. We have said in Floccher’s Case, 221 Mass. 54, 55, that if the claimant is not to be subjected to unusual risk and danger arising from the anaesthetic to be employed or from the nature of the proposed operation, it is the claimant’s duty to submit, if it fairly appears that the result of such operation will be a substantial physical gain. Whether in a particular case there is such risk and danger, and whether it fairly appears that a substantial gain will result from a suggested surgical operation, are generally questions of fact to be determined by the Industrial Accident Board. Instances may occur when all the evidence is so clear that the decision presents merely a question of law. In the case before us, however, two experts testify that the outcome of the operation suggested is uncertain. In their opinion the *94benefit is probable, there is a chance of great improvement, but the operation is considered.a major operation and a good result cannot be promised. We cannot say that, as matter of law, it fairly appears that substantial gain will result, nor that the denial of the ruling, that “the claimant unreasonably refuses to submit to an operation which, in all probability, will repair the damage to his knee,” was error. It follows that the insurer was not entitled to the ruling that compensation be suspended, if, after a reasonable lapse of time, the claimant refuses to go under operation.
¶2The extent of earning capacity is a question of fact; and the finding of the board, on appeal, cannot be disturbed. Weir’s Case, 252 Mass. 236, 238.
¶3 Decree affirmed.