Femoral Nailing
Femoral nailing is an attractive option for the treatment of hip fractures. This is a minimally invasive technique only requiring small incisions of the skin and does not require the large dissection needed for other techniques.
A metal rod (or nail) is placed within the femur, spanning across the fractured segment and is secured into place, most of with screws. One thicker screw is placed through the femoral neck and into the femoral head near the hip joint to prevent the fracture from rotating and compress across the fracture site, and one screw is placed near the end of the rod to prevent it from migrating inside the bone.
Patients are immediately able to walk after surgery because the metal rod helps to share the load of weight through the femur. This way patients can mobilize early, prevent the development of blood clots or a pneumonia and return to their pre-injury level of function and activity.
Hip Fracture Surgery
Performing a total femur replacement is essentially performing a total hip replacement and total knee replacement at the same time followed by connecting the two components through an adjustable, modular stem. However, a total femur replacement requires significantly longer operating time than most other revision arthroplasty surgeries. This increases the risk of wound contamination and subsequent development of infection.
Patients should expect a notable incision from their hip extending to below their knee. Excessive dissection is required to remove the underlying femur; however some osseous components may be left in place in order to facilitate prosthesis incorporation.
Flap coverage may be required for adequate soft tissue coverage of the total femur implant. Patients should be aware that skin or muscle tissue from other areas of their body may be utilized.
Stryker Gamma Nail
The Gamma nail was first used in 1985 and the design has been improved upon over the years. A small incision is made lateral portion of the buttocks and the nail is inserted inside the femur. Attached to the device is a guide that ensures that the trajectory of the screws placed thought the middle of the nail is correct.
Two additional small incisions are made so that the screws securing the nails position can be placed. The nail itself is made from specially treated titanium that comes with multiple options to best fit the anatomy of the patient’s femur.
The larger screw placed through the nail and into the femoral head helps control compression and can help lessen shortening of the femoral neck seen after treatment with other devices (such as the dynamic hip screw). There is an additional screw at the top of the nail that can prevent any rotation at the fracture site which is a common problem when using other systems.
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Sliding Hip Screw
The technology used to repair or fix the hip has evolved significantly. Initial repair methods used basic plate and screw constructs that required prolonged periods of nonweightbearing on the injured leg. However, as our understanding of hip fractures has evolved it has become apparent that any method we use to fix the hip needs to allow for immediate ability to put full weight on the leg, especially in elderly patients.
Due to this understanding the technology surrounding hip fracture fixation has evolved significantly and there are now several highly specialized tools to fix the hip. Which method is used depends on the “stability” of the fracture. Simply, a fracture is considered stable if the outside, or lateral, surface of the bone is intact. Stable fractures can be fixed using a special plate and screw called a sliding hip screw, while unstable fractures are fixed using a nail down the middle of the bone.
The sliding hip screw aids in healing of the hip fracture by allowing the large screw in the bone to piston through the plate on the side of the bone. This transfers downward “shear” force into “compressive” force through the site of the fracture, which allows for more efficient healing. These constructs also allow for immediate weightbearing after surgery, allowing for patients to participate in physical therapy and start their recovery sooner.
DePuy Synthes Dynamic Hip Screw (DHS) System
The Synthes Dynamic Hip Screw (DHS) is one of several options for sliding hip screw constructs. The large screw in the bone, called the lag screw, is made of stainless steel and has threads at the tip of the screw only to allow for more effective compression. The femur side plate is also made of stainless steel and is lower profile than other competing options, which leads to less irritation to the surrounding muscle and tissue after placement.
Both the plate and screw come in several size options to allow for customization to each patients’ anatomy. The DHS system is particularly unique because of the number of options in each component of the construct: plate length, barrel length, barrel angle, and lag screw length.
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Hip Prosthesis
Hip prostheses were first developed to treat chronic infections within the hip joint in 1891 using ivory to replace the femoral head. Later designs used glass and stainless steel to replace the femur. The problem with this procedure is that the pelvis side (acetabulum) of the hip joint was left alone, and therefore areas that could be causes arthritic pain were left in place.
It was not until the 1950s that surgeons started replacing the acetabulum as well with a metal cup that articulated with a metal femur prosthesis. With advances in technology the current implants are often ceramic or metal femur prosthesis that articulates with a polyethylene (plastic) cup. In the setting of revision surgery for hip prosthesis or in the setting of trauma to the hip prosthesis, there is associated bone loss. More bone loss requires a larger implant to replace that bone loss.
Eventually the amount of bone loss was significant enough that it resulted in loss of the muscle attachments to the femur. In the 1980s, the proximal femoral replacement (PRF) was created. A PFR is often made of the same material as a standard partial or total hip replacement, however, is much larger in size. It is designed to replace all portions of the femur near the hip joint. This includes the ball portion of the hip joint and the regions where muscles attach.
The reattachment of tendons allows for motion. Additionally, this provides stability to the implant and reduces the risk for postoperative dislocation. This results in a functional hip joint without a patient’s normal bone. A PFR is then cemented into the main shaft of the femur further down the patient’s thigh, creating rigid fixation for the implant. Besides periprosthetic fractures, these implants can also be used in patients with significant bone loss from infections or tumors.
Stryker Global Modular Replacement System Proximal Femur™
The Stryker Global Modular Replacement System Proximal Femur™ allows the surgeon to recreate the femur part of the hip joint completely with a prosthesis. It has tunnels that allow for the restoration of hip motion with reattachment of the hip flexor, extensor, and abductor muscles, which bring the leg out to the side.
During its assembly, it has the option of building length into the contrast. This allows surgeons to ensure that they have restored a patient’s leg to the correct length. Additionally, it has the option of interfacing a patient’s native acetabulum or with a prosthesis from a total hip replacement.
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