Fusion surgery is frequently used to treat arthritic joints in the foot and ankle. With fusion surgery, the two sides of the joint are roughened with a burr or small chisel. Next, the two bones to be fused, i.e. the two bones that make up the arthritic joint, are screwed together with one or more metal screws. The foot and ankle are then further immobilized with a cast. In the weeks and months following surgery, the body is “tricked” into thinking that there is a fracture present at the fusion site and heals this with bone. As such, the two bones become one and are considered “fused.” Because there is no longer an arthritic joint present, the pain is relieved.
If you are undergoing fusion surgery, your cooperation is essential in order to obtain a successful fusion. In approximately 10% of patients, the fusion does not “take.” That is, the two bones that were to be fused remain separate and do not unite. This is called a “non-union” and often results in a lack of pain relief from the surgery.
So what can you do? Probably the most important thing is to follow your postoperative weight- bearing instructions. Most patients with fusion surgery are kept “non weight-bearing.” The reason for this is to prevent motion at the fusion site. Motion prevents the two bones from fusing. If you put weight on your foot after a fusion, this can lead to motion, even with the screws and cast. Also, if significant force is applied even just once, the screws that are used to hold the bones together can loosen. This will also lead to motion, and prevent the fusion from healing. Thus, it is essential to remain completely and strictly non weight-bearing if you are instructed to do so following your fusion surgery.
Along these lines, at some point you will be instructed by your physician to begin progressing your weight-bearing. This does not mean that you can go ahead with unlimited walking and weight-bearing. When a fusion heals, it initially heals with unorganized, or “woven”, bone. This is weaker bone that eventually becomes organized and structured into what is called “lamellar” bone. Lamellar bone is much stronger and considered to be mature bone. The process by which your fusion progresses from woven bone to lamellar bone is a gradual one. Some weight is needed to stimulate this process. However, too much weight can cause a nonunion to develop in the weaker, woven bone. How much weight bearing is enough? Listen to your body and let your symptoms be your guide. If you have pain when you begin to weight bear on your fusion, this means that you may be walking for too long or putting too much weight on the fusion. If this is the case, you should decrease both the amount of weight you are putting on the fusion and also the duration of your weight bearing. You can then gradually increase from there. Finally, it is important to avoid cigarette smoking while your fusion is healing. Cigarette smoke decreases fusion healing. If a family member smokes, they should do so outside to minimize your exposure to second-hand smoke.
In our practice, hundreds, if not thousands, of patients have undergone successful fusions. These patients enjoy pain relief and restoration of function. You play a critical role in your own healing process on the way to joining this group. Your cooperation and compliance with postoperative instructions is critical. Please, follow your weight-bearing instructions 100% of the time. Remember, it takes just one step to cause a nonunion. If you need help and more practice with your crutches or walker, please feel free to contact us and we will set up further physical therapy training sessions for you.