Walking is the therapy, and the knee tells you the next day whether it was too much.

The early weeks: short walks, several times a day, with support

The AAOS patient guide says most patients walk with a cane, crutches or a walker soon after surgery. The program is graduated: first at home, later outside ¹. Its exercise guide sets the early target at 30 minutes of walking, 2 to 3 times a day ².

Support comes off in stages. The guide suggests a single crutch or cane once a patient can stand and walk for more than 10 minutes without weight through the walker. That is often about 2 to 3 weeks after surgery ².

The guide also says patients may walk as much as they like, with one condition: walking does not replace the bending and strengthening exercises the surgeon and therapist prescribe ³. A long walk that leaves no energy for the exercises has the priorities backwards.

What sensors show for the first six weeks

Two large studies have measured this directly. In 794 knee replacements with a sensor in the implant, 90 percent of patients transmitted daily data. Between week 1 and week 6, qualified step count rose 733 percent, walking speed 50 percent and stride length 17 percent. Step counts were lower at higher body mass index, and lower in women than men at every time point ⁴.

A second study followed 686 patients through a phone app from 6 weeks before surgery to 24 weeks after. Gait was at its worst at week 2. Walking speed fell from 1.01 to 0.79 metres per second, and timing asymmetry, the measurable form of a limp, rose from 12.5 to 52.6 percent. Asymmetry was back to baseline by week 13 and walking speed by week 21. The authors note that gait quality recovers more slowly than step counts ⁵.

Read together, the two say something useful. The number of steps climbs steeply in the first six weeks. The quality of those steps, their speed and evenness, takes months. A limp at week 2 is what the data show for most patients, not a sign that something has gone wrong.

Useful soreness versus overdoing it

Judge a walk by the next morning, not by the walk itself. Some soreness after activity is part of recovery. The signals that a walk was too long arrive the next day: more swelling than before, less bend than before, or a limp that is worse rather than better ⁵.

Swelling is the one to watch, and the AAHKS pain guide calls reducing it key. It advises ice for 20 to 30 minutes, then 30 minutes off before reapplying, with a towel between ice and skin. It also advises elevating the leg with the foot above the level of the heart ⁶.

The practical rule that follows: shorten the next walk rather than skip it, keep the frequency, and let the swelling settle before distance goes up again. What counts as a normal day-to-day rise is a question for the therapist who sees the knee each week.

Stairs: technique first, then timing

Before leaving hospital, patients are asked to show they can climb up and down two or three stairs with their walking aid ³. The AAOS guide warns that stairs are harder in early recovery than level walking and suggests handrails along stairways at home ¹.

The technique in the exercise guide is fixed: lead up the stairs with the good knee and down with the operated knee, in the phrase "up with the good, down with the bad". Use the handrail, take one step at a time at first, and do not attempt steps higher than the standard 7 inches ².

On timing, one small prospective study followed 21 women through bilateral knee replacement. Stair ability improved at 8 weeks, and by 26 weeks it was no different from healthy controls. Stair ability tracked pain and fear of falling, so confidence recovered later than the joint ⁷. In a separate study of 84 patients, quadriceps strength in the operated leg and balance before surgery predicted stair climbing one month after it ⁸. The strengthening exercises are how stairs get easier.

When to call your surgical team

Most next-day soreness is a walk that was a little long. A few things are not, and the AAOS guides list them ¹³:

• Calf pain, tenderness or redness above or below the knee, or new swelling in the calf, ankle and foot, which can signal a clot ¹.
• Sudden shortness of breath or chest pain, which needs immediate medical attention ¹.
• Fever, chills, increasing redness or drainage at the wound, or pain that is rising rather than easing ³.
• A knee that bends less week on week rather than more, which the therapist and surgeon will want to see rather than hear about later.

Walking is meant to be the part of recovery you can do on your own. The distance is yours to set within what your surgeon and therapist advised; the warning signs are theirs to judge.