The Breg Polar Care Cube is a cold therapy device that circulates ice water through a pad wrapped around your knee, delivering consistent cooling after surgery or injury. Setting it up is straightforward, but a few details about filling, connecting, and timing your sessions will help you get the most out of it and avoid common frustrations.
How the Device Works
The Polar Care Cube is essentially a small cooler with a built-in pump. You fill the reservoir with ice and water, connect a hose to a wrap-style pad, and the pump circulates cold water through channels in the pad. Unlike a regular ice pack that warms up quickly and unevenly, this system keeps a steady flow of cold water moving across your knee for as long as there’s ice in the reservoir. That said, clinical research comparing continuous-flow cryotherapy devices to traditional ice packs has found no significant difference in pain scores or knee swelling after total knee replacement. The main practical advantage is convenience: you don’t need to swap out ice packs every 20 minutes.
Filling the Reservoir
Open the lid and fill the cooler with ice first, then add cold water. You want roughly equal parts ice and water, enough that the ice is mostly submerged but the reservoir isn’t overflowing. The water level needs to stay above the pump intake at the bottom of the unit, or the pump will run dry and stop circulating. As ice melts during your session, the water level rises slightly, so don’t fill it to the absolute brim. If you notice the pad losing its chill after 45 minutes to an hour, open the lid and add more ice.
Connecting the Pad and Hose
The knee pad has two hose connections, one for inflow and one for outflow. The connector plugs into a port on the front of the unit. Line up the connector and push it in until it clicks. Before you wrap the pad around your knee, make sure the hose isn’t kinked or twisted at any point between the unit and the pad. Even a slight kink can stop water flow entirely.
Position the pad so it covers the front and sides of your knee, with the cooling channels centered over the area that needs it most. If your pad came with straps or a wrap sleeve, secure it snugly but not so tight that it compresses the hose connections. You want the pad to stay in place without restricting circulation in your leg.
Starting a Session
Once the hose is connected and the reservoir is full, turn the unit on. You’ll hear the pump start, and within 30 seconds to a minute, you should feel the pad getting cold as water begins circulating. If you don’t feel any cooling after a couple of minutes, check for two things. First, confirm the hose isn’t kinked anywhere along its length. Second, there may be air trapped in the line. You can release it by pressing the small black plus-shaped valve inside the unit connector. A little water may come out when you do this, which is normal.
Always place a thin layer of fabric between the pad and your bare skin. A T-shirt, pillowcase, or the fabric sleeve that comes with some pad kits works fine. Direct contact between the cold pad and skin increases the risk of a cold injury, especially during longer sessions when you might fall asleep or lose track of time.
How Long and How Often to Use It
For the first five to seven days after knee surgery, aim for at least five sessions per day, each lasting about 20 minutes. That’s the minimum. Many surgeons recommend longer or more frequent sessions during the acute recovery phase, particularly in the first 48 to 72 hours when swelling peaks.
Because the Polar Care Cube delivers a more controlled level of cold than a bare ice pack, it can safely be used for longer stretches than you’d typically leave an ice bag on your knee. Some protocols allow extended use including overnight sessions. However, longer sessions only make sense if you’re using a barrier layer between the pad and your skin, and if you’re checking your skin periodically for signs of irritation, numbness beyond the normal cooling sensation, or color changes.
Elevating your knee while using the device improves results. Prop your leg up on pillows so your knee sits above heart level. Cold therapy and elevation work together to reduce swelling, and combining them is more effective than either one alone.
Troubleshooting Common Problems
The most common issue is the pump running but no cold water reaching the pad. Almost every time, this comes down to one of two causes: a kinked hose or trapped air. Straighten the full length of the hose from the unit to the pad and check both connection points. If the hose is clear but water still isn’t flowing, press the black plus-shaped valve inside the connector to bleed out any air bubbles blocking the line.
If the pad feels cold initially but warms up quickly, your ice has melted. Open the lid and check. During hot weather or in warm rooms, ice melts faster than you’d expect. Keeping the unit on a hard floor rather than carpet or a couch cushion helps insulate the bottom. You can also drape a towel over the closed lid to slow heat absorption.
A pump that won’t turn on at all usually means the water level has dropped below the intake. Add more water and ice. If the unit still won’t start, check that the power cord is fully seated.
Keeping the Unit Clean
After each day of use, dump out the water and leave the lid open so the reservoir can air dry. Standing water left in the cooler overnight becomes a breeding ground for mold and bacteria, especially in a warm room. Every few days, wipe the inside of the reservoir with a clean cloth. If you notice any film or discoloration building up, a mild soap and water rinse will take care of it. Rinse thoroughly so no soap residue gets into the pump.
When you’re done with the device entirely, drain it completely, clean the reservoir, and store it with the lid open. Detach the hose and let both ends dry before coiling it for storage.
Who Should Be Cautious
Cold therapy devices are not safe for everyone. If you have peripheral vascular disease, Raynaud’s disease, or diabetes, cold exposure can cause tissue damage more easily because blood flow to your extremities is already compromised. These conditions don’t necessarily rule out using the device, but they require specific guidance from your surgeon or doctor about how long and how intensely you can safely ice your knee.