Efficacy of rhBMP-2-loaded self-setting calcium phosphate cement combined with nose ring drain technique in the treatment of gouty tophus with bone defect of the first metatarsophalangeal joint

Gout is a painful form of arthritis that occurs when the body produces too much uric acid, a waste product that normally dissolves in the blood and leaves the body through urine. When levels get too high, sharp crystals form and settle in the joints, causing sudden, intense swelling and redness. Over time, if the condition is not managed, these crystals can clump together into hard, chalky lumps called tophi. These lumps are not just surface bumps; they can grow deep into the body, eating away at the soft tissue and the bone itself. The big toe joint is a common place for this to happen, and when the bone is destroyed, it leaves a hollow space that is difficult to fill and even harder to heal. Surgeons have long faced a dilemma here: removing the tophi often leaves a large hole in the bone that needs to be filled, while the remaining crystals and fluid in the wound make it very easy for the skin to get infected or fail to close.

A team of researchers at the Chongqing Orthopedic Hospital of Traditional Chinese Medicine set out to find a better way to handle this specific problem. They focused on patients who had tophi in their big toe joints that had already eaten away a piece of the bone. The researchers compared two different surgical approaches. The first group received a standard operation where the surgeon removed the tophi and the damaged bone, then placed a simple drainage strip in the wound to let fluid escape. The second group received a more advanced treatment. In this group, after the surgeon cleared out the tophi and the dead bone, they packed the empty space with a special paste. This paste was a self-setting calcium phosphate cement, a material that hardens inside the body to act like a temporary bone, mixed with a protein called rhBMP-2. This protein acts as a signal to the body's cells, encouraging them to grow new bone to fill the gap permanently. To handle the fluid and crystals that might remain, the surgeons used a technique called a "nose ring drain." Instead of a single strip, they threaded two or three flexible tubes through the wound in a loop, entering high and exiting low, so that fluid could flow out continuously and the tubes could be moved around to clear any blockages.

The study looked at forty patients in total, with thirteen receiving the new combined treatment and twenty-seven receiving the standard care. The results showed that the new approach worked significantly better in several key areas. Patients who received the bone-filling paste and the looped drainage tubes healed their skin wounds much faster than those with the standard drainage. In the group with the new treatment, only three out of twenty feet had wounds that took longer than two weeks to heal, whereas in the standard group, fifteen out of thirty-two feet had this delay. More importantly, the new method prevented serious complications. None of the patients in the new treatment group developed an infection or had a flap of skin die, while the standard group saw a few cases of both. The researchers also found that the new treatment reduced the levels of inflammation markers in the blood more effectively than the standard surgery. While both groups saw their pain levels drop and their ability to walk improve, the group with the new technique reported better overall function in their feet by the end of the study.

The researchers believe the success of this method comes from how it tackles the two main problems at once. The bone paste fills the empty space left by the removed tophi, which stops the wound from collapsing and gives the body a scaffold to build new bone. At the same time, the looped drainage tubes act like a continuous cleaning system. Because the tubes can be moved and irrigated, they prevent the buildup of the sticky fluid and leftover crystals that often cause infections and slow down healing. This combination allowed the surgeons to remove the tophi more completely without fearing that the wound would not heal. The study did not find a difference in the patients' overall uric acid levels, which is expected because the surgery removes the local lumps but does not change the body's chemistry; patients still need medication to control their uric acid long-term. However, for the specific problem of a damaged big toe joint, this combined technique offered a clear path to faster healing and fewer complications. The authors suggest that this approach is a valuable tool for surgeons facing these difficult cases, though they note that larger studies are needed to confirm these findings over the long term.