(concurring in part and dissenting in part). I concur in the opinion of Justice Williams except that I respectfully dissent as to part III.
The plaintiff had been paid 500 weeks of workers’ compensation benefits as a result of a 1959 injury to his right knee. He last worked in 1967. The last payment was made on July 1, 1974. On August 12, 1974, the plaintiff filed a petition alleging total and permanent disability based upon loss of the industrial use of both legs as a result of the 1959 injury to his right knee. Dr. James W. Lyons, orthopedic surgeon, had been the plaintiff’s physician over the years. In his deposition, he said that the plaintiff had not complained about the left knee prior to September 1, 1974 — over two months after final payment of benefits. When he had last seen the plaintiff before that date, in April, 1973, the only complaints concerned the injured right knee.
*126The Workers’ Compensation Appeal Board (WCAB) held that the plaintiff failed to show that he had a total and permanent disability within the limitation period of MCL 418.361(2)(g); MSA 17.237(361)(2)(g).1 The WCAB stated:
"From our review of the record, we make a finding of fact that plaintiff did not sustain his burden of proof of industrial loss of both legs prior to the expiration of 500 weeks from the date of his December 1, 1964, injury.
"Plaintiff’s testimony above, taken at face value, does not meet the test of Burke [v Ontonagon County Road Comm, 391 Mich 103; 214 NW2d 797 (1974)] in establishing permanent and total disability. Plaintiff says his left leg 'began to bother him’ around May of 1974. This statement is too vague for us to find as fact that at that time he had lost the use of that leg. Neither does the fact that plaintiff had been using a cane for three years meet the test of Burke, supra.
"James W. Lyons, M.D. and board-certified orthopedic surgeon, treated plaintiff and was deposed on December 13, 1974. He testified that he saw plaintiff September 17, 1974, and for the first time, plaintiff complained of his left leg. Dr. Lyons had previously seen plaintiff in April of 1973, and at that time plaintiff had no complaint regarding his left knee. The x-rays taken in September, 1974, were the first time the left knee had been x-rayed.
"Dr. Lyons’ testimony that the first time plaintiff complained to him of his left leg was on September 17, 1974, two-and-a-half months after 500 weeks had expired, further helps defeat plaintiff’s claim, particularly *127in light of plaintiffs testimony that Dr. Lyons was his only doctor.
"Plaintiff simply has failed to sustain his burden of proof of total and permanent disability as required in the test of Burke, supra, within the period provided by subsection (2)(g).”
The WCAB’s conclusion is clear: regardless whether the plaintiff subsequently suffered from a loss of the industrial use of both legs, he did not prove that such a disability existed prior to June 1, 1974, which was "30 days before the expiration of 500 weeks from the date of injury”. See MCL 418.361(2)(g); MSA 17.237(361)(2)(g).
My colleague, however, would remand "because other legally pertinent testimony was available” that "indicates that the WCAB may not have properly applied the Burke legal standard”. I cannot agree that the WCAB opinion allows us an opportunity for such speculation.
The "legally pertinent testimony” upon which a remand would be premised includes three statements by the plaintiff and one statement by his doctor. Two of the three statements by the plaintiff that are quoted in my colleague’s opinion are in the present tense, and .were spoken on November 12, 1974. See ante, p 123. That date was 5-1/2 months after June 1, 1974, the date on which plaintiff was required to show that a disability existed. In light of the WCAB finding that the plaintiff did not establish that he had a permanent and total disability on June 1, 1974, it is not surprising that the WCAB did not mention this testimony concerning the plaintiff’s condition five months later. While the third quoted statement is in the past tense, this statement, "[B]oth [right and left knees] bothered me, sir”, see ante, p 123, *128was merely a reiteration of testimony that the board did expressly consider.
The only other testimony in the record upon which the possibility of legal error would be premised is the following statement of plaintiffs doctor and is based on plaintiffs problem with his right knee:
"[HJere’s a note from ’73. I said my initial impression is that he shouldn’t be doing the type of work he did previously if he does a lot of walking. I said he could do a desk-type job or a supervisory-type job if it did not involve a lot of walking. And this was discussed with him.”
This brief assertion that the physician’s initial impression in 1973 was that the plaintiff should not do "a lot of walking” because of his right knee problem is, at best, a tenuous ground upon which to conclude that the WCAB committed legal error in not finding that plaintiff had lost the industrial use of both legs prior to June 1, 1974. Parenthetically, the physician never explained what he considered to be "a lot of walking” and the phrase is not free from ambiguity. However, it would be unreasonable indeed to conclude that whenever a physician advises a patient against doing "a lot of walking”, the patient has thereby lost the industrial use of both legs.
The question whether the plaintiff lost the industrial use of both legs within the statutory period is a question of fact for the WCAB. See Miller v Sullivan Milk Products, Inc, 385 Mich 659, 666, 669; 189 NW2d 304 (1971). This Court is not free to isolate certain portions of the testimony below, draw its own factual inferences therefrom, and then rule that a remand is required because those inferences suggest the bare possibility of *129legal error. We are bound by a constitutional provision that places factfinding responsibilities in the WCAB. Const 1963, art 6, § 28. See, also, Thornton v Luria-Dumes Co-Venture, 347 Mich 160, 162; 79 NW2d 457 (1956). We would transgress that provision if we were to remand in the present case.
We would reverse the judgment of the Court of Appeals that MCL 418.361(2)(g); MSA 17.237(361)(2)(g) violates the plaintiff’s due process and equal protection rights, and would affirm the decision of the Workers’ Compensation Appeal Board.
Fitzgerald and Ryan, JJ., concurred with Coleman, C.J."(2) Total and permanent disability, compensation for which is provided in section 351 means:
"(g) Permanent and total loss of industrial use of both legs or both hands or both arms or 1 leg and 1 arm; for the purpose of this subdivision such permanency shall be determined not less than 30 days before the expiration of 500 weeks from the date of injury.”