As hip replacement is a major and complicated surgery that requires adequate skill and expertise from the surgeon, performing it is always associated with significant risk. While the medical establishment continues to find ways to minimize such risks (such as by perfecting minimally invasive surgical procedures) or to prevent the development of any ensuing complication, a certain percentage of people receiving artificial hip implants will develop unwanted outcomes. One of the unintended consequences of hip replacement is pain—either as a constant, low-level annoyance or as sudden stabs of discomfort whenever one assumes a certain posture or moves in a particular way.

Artificial hip replacements are far from being perfect. And when they do go bad, and you end up having to endure some amount of pain, the following are just some of the (hopefully) helpful answers to your “What could be causing all this pain?” questions.

Discrepancy in post-operation length of your legs: there is always the possibility that after the hip replacement surgery, you may end up with the operated leg being longer than the other one. In fact, this unwanted outcome is among the most common complaints among hip implant recipients. This situation often arises from various mistakes: wrong implant choice, too large femoral component, or the implantable ball may not have been snugly fitted in the socket. It is important to note, however, that it is usual for patients soon after the hip replacement operation to “feel” that the leg with the implant seems longer. The patient should wait a few months and if the feeling does not go away, it is probably a true leg length inequality. If one leg truly ends up being longer than the other, this inequality would put excessive stress on the hip joints, thereby causing pain.

Metal, ceramic or plastic debris accumulating in the tissue and bone surrounding the hip implant: the kind of debris that is shed by your implanted device depends on what material they are made of. The original bone and socket hip joints rely on the cartilage to provide cushion and lubrication. When these bones are removed and replaced with an artificial bone-and-joint structure, the artificial replacement of course has no self-generating lubrication. Instead, the material that makes up the ball and socket will wear over time, entering the blood stream or accumulating in the tissue or bone surrounding the implant.

Recently, the type of implant that has gained some notoriety regarding the shedding of too much metal debris is the metal-on-metal hip replacement. Originally designed to surpass the older metal-on-plastic models in terms of durability and minimal debris shedding, these all-metal implants turn out to cause more problems. The debris causes pain in the immediate vicinity, but the more alarming aspect of this is the little known health effects of such metal debris as it circulates in the blood stream.

Inflammation: Closely related to debris-related pain is inflammation. Worse, the mechanism of this type of inflammation can be complicated. As the artificial hip implant wears, producing particulates, sometimes such debris can spring special cells to action, causing them to consume the nearest bone. If sufficient bone is eaten away, this could loosen the implant. An artificial hip replacement that is no longer snugly placed in the right position can start a cascade of pain-causing consequences. If the inflammation is not severe, the doctor usually prescribes some anti-inflammatory medicine. If worse comes to worst, however, the only way to remove the pain is by removing the cause of it: by having the patient to undergo a revision surgery to correct the implant or remove it altogether.

Bone fracture: Sometimes, the natural bone can also fracture due to its interaction with the implant. For example, when the femoral component of an implant is inserted into the reshaped femur, mistakes could be made that could leave the femur prone to shattering. In other cases, bone loss could also occur in the area surrounding the implant, thereby also leaving the bone prone to the development of hairline fractures that could worsen over time. In some cases, chronic pain is caused by these tiny bone fractures that go unnoticed until the problem literally comes to a breaking point.

The above list of sources of pain after hip replacement surgery is by no means complete. The truth is, many hip replacement patients suffering from one form of chronic pain or another are befuddled over the actual source of their pain. When doctors are unable to pinpoint exactly the source of pain, patients are giving pain killers that could be addictive. In any case, the existence of pain is an indication that something is wrong, and it should be addressed sufficiently and thoroughly.