The upper femur (thigh bone) has a unique anatomy that predisposes it to fracture when the bone becomes osteopenic (less dense). This can also be seen in patients with osteoporosis which is a different disease pattern than just generalized osteopenia. Osteopenia is defined as reduced mineralization of the bones. That is to say that the bones have less density of calcium and metallic ions in them that gives bone its strength. Osteoporosis, however, means that the bone quality predisposes it to fracture. This would be analogous to different types of wood that you would find in your home or hardware store to purchase. Obviously a very hard piece of plywood would be harder to break and would accept screws more firmly than a very thin piece of balsa wood or some synthetic sawdust fabrication.
The anatomy of the upper femur (hip joint) is comprised of four different areas. The femoral head is the ball part of the femur and is the part that makes up the ball of the ball and socket. Of note, the other side of the socket called the acetabulum, Latin for “Vinegar Cup”, is considered a separate type of injury; although, we are seeing the injuries to the acetabulum increase as well as the types of injuries which should be mentioned in a separate article.
The second part of the upper femur is the femoral neck and this is the perch upon which the ball sits before the left turn occurs down the femoral shaft. I often make the analogy to patients that the femoral neck is the junction between what you would picture as a single scoop ice cream ball and a sugar cone. It is a stress riser which means it is a point of maximum stress and a point where forces when a patient falls can be absorbed and focused causing injury. It is narrower than the part below it and above it and acts as “a cord” area of the upper femur.
Below the femoral neck is the trochanter area. This is divided into the intertrochanteric area (on an x-ray this would be the area between the larger and smaller bumps of the upper femur where two major muscle groups attach) and the sub trochanteric area which is a lesser relevant area for this article (to be discussed under separate text as well).
In summary for this decision we will be talking primarily about femoral neck fractures and intertrochanteric fractures. Other anatomic facts important for this are that femoral neck fractures in the femoral neck area are within the hip capsule. I often describe this to patients as the area when you are cleaning out a food source for preparation; when you cut through or tear apart a chicken or turkey leg or wing it is the junction between two bones that has very smooth cartilage, very slippery surfaces on it and not a lot of meat or muscle attached to it. In the human anatomy the capsule of the hip joint starts just above the intertrochanteric area and ends at the acetabulum or the hip socket. This area is special because it does not have significant blood flow to the outside and the blood flow that supports the bone in this area comes primarily from inside the bone or intramedullary arteries. When that part of the bone is broken the intramedullary arteries tethered to the hard bone are torn off. The blood flow or ability of that bone to survive an injury and heal itself is compromised significantly to the point where trying to fix those fractures by putting screws, plates or pins through the area may result in up to a 30-40% complication rate.
The area of the intertrochanteric area is outside of the hip capsule where there are two major muscle groups attached to the femur. The muscle groups that move the leg out, in and up. When there is a fracture in this area the outer muscle covering has a rich blood supply and really predisposes this area to heal much more reliably and much more consistently.
This is why we often treat intertrochanteric fractures, fractures below the femoral neck and the capsule of the hip joint with rods, plates, screws or some other combination of devices to try to get them to heal because they more predictably heal with that blood supply.
Typically and historically, orthopaedic surgeons have done what we call hemiarthroplasties (half hip replacement) for displaced fractures of the femoral neck. Younger patients with femoral neck fractures undergo an open reduction internal fixation (ORIF) which means a surgical wound is created, the patient’s deformity is reduced, the bone is lined up as best possible, and plates, screws or some combination of pins or implants are used to fix the fracture to allow healing of the bone around it. What determines our decision for these two things of course is the demand of the patient, the instability of the fracture pattern (complexity of fracture), and other factors that are patient specific. Fractures of the intertrochanteric area are by enlarge treated with either a plate on the side of the bone with a screw heading up into the femoral head or a rod inside the bone with a screw heading up into the femoral head. The two devices, the rod and/or plate, are connected to the screw with a small joining screw on the inside that allows for compression of the bone. This allows for early walking, weightbearing and provides initial significant stability.
Currently the science is pointing towards the idea that femoral neck fractures that ordinarily we would do a half a hip replacement on should be treated with a total hip replacement. A total hip replacement is when a metal cup is placed into the native socket of the hip joint and screwed in place and allow for the bone and pelvis to grow into it over time. A total hip replacement is what is done routinely and commonly for hip replacement when there is both loss of cartilage on the side of the hip socket as well as the femoral head side.
In the past this was tried, however, hip replacements had smaller ball and socket constructs. They were not stable enough to stay in place during the recovery period because the ball and socket construct was smaller and less stable. After fracture the patient’s hip replacement has much larger and stable constructs with much larger ball and socket joints to allow for more stability, and for a little bit more freedom in movement during the early recovery stages when muscles are healing. This is significantly different and requires a lot more control of the hip joint. When a replacement is performed for arthritis it is a controlled situation and there is very little to no muscle damage prior to the surgery.
In summary, with the advent of large ball and socket constructs, the patients now seem to have fewer dislocations and complications with primary total hip arthroplasty after fracture.
The scientific literature seems to be bearing this out over the past ten years; there have been many studies that show fewer dislocation rates, less overall cost and better functional outcomes as measured by patients when a primary total hip replacement is done for a femoral neck fracture. In fact, we are starting to consider primary total hip replacements for fractures of the intertrochanteric area with different types of devices. The limitation on this right now is that it requires just a slightly more specialized hip replacement that most surgeons are not widely trained to use at this point.
In Summary, this represents a very cursory overview of the decision points in treating hip fractures. I would be more than happy to discuss anything with any patients or families that are interested by appointment at any time. It is very important to me that patients are educated and not simply just receiving healthcare. I also believe very much in the use of Internet, web based technology, videos, YouTube videos as well as our own orthopaedic website, the American Academy of Orthopaedic Surgeons videos and any other website that has much more detail and reference for the scientific information presented in this article.
Disclaimer: This article should not be intended to provide medical advice and should not be used in any generalized decision/treatment process. Any and all decisions regarding patient care should be done on an individualized basis with consultation from a treating physician. I would not submit any warranty or guarantee of outcome based on the information or science given in this article as this is an evolving topic.