The hip is a ball and socket joint comprising of the femur (thigh bone) and the pelvic bone. The head of the femur (ball) articulates with a cavity (socket) called the acetabulum in the pelvic bone. To facilitate smooth and frictionless movement of the hip joint, the articulating surfaces of the femur head and acetabulum are covered by spongy articular cartilage. Injury, wear-and-tear and certain diseases can result in the wearing away of the cartilage tissue, causing painful rubbing of bones. Hip replacement surgeries have long been the choice of treatment, where the damaged parts of the joint are removed and replaced with a prosthesis. However, in young active patients, the prostheses are highly prone to wear-and-tear, and the need for repeat surgery. Hip preservation is a surgery that overcomes the limitations of joint replacement.
Some of the conditions indicated for hip preservation surgery include:
- Femoroacetabular impingement (FAI): friction in the hip joint from abnormal bony irregularities
- Hip dislocation: head of the femur moves out of the socket
- Hip dysplasia: congenital hip condition characterized by a shallow acetabulum
- Labral tear: tear or separation of the labrum, a cartilaginous ring that surrounds the socket and seals the hip joint
- Avascular necrosis: disrupted blood flow to the hip joint, causing death of bone tissue
Hip preservation surgery includes various techniques:
- Periacetabular osteotomy: Periacetabular osteotomy is a surgical procedure to treat hip dysplasia. This involves cutting the acetabulum from the pelvic bone and repositioning it with screws to allow for a better fit of the femoral head. The procedure reduces pain, restores function and prevents further deterioration of the hip joint, thereby increasing the life of the hip joint and postponing total hip replacement.
- Surgical hip dislocation: Surgical hip dislocation is a surgical technique that involves the dislocation of the hip joint during surgery to facilitate easy access to the inside tissues of the hip joint. It helps your surgeon to clearly view and treat abnormalities present deep into the hip joint.
- Femoral osteotomy: An osteotomy is a surgical procedure that involves cutting and reshaping of a bone. The femur is cut at the end close to the hip joint and realigned so that it forms a normal angle. This improves the distribution of force placed on the joint and prevents wear-and-tear of the cartilage.
- Hip arthroscopy: Arthroscopy, also referred to as keyhole or minimally invasive surgery, is a procedure in which an arthroscope is inserted into a joint to check for any damage and repair it simultaneously. Hip arthroscopy is a surgical procedure performed through very small incisions to diagnose and treat various hip conditions.
The various hip preservation surgeries for severe hip pain and dysfunction in young and active patients have been found to be beneficial, and avoid or delay the need for hip replacement surgery.
Hip implants are artificial devices that form the essential parts of the hip joint during a hip replacement surgery. The hip implants vary by size, shape, and material. Implants are made of biocompatible materials that are accepted by the body without producing any rejection response. Implants can be made of metal alloys, ceramics, or plastics, and can be joined to the bone. The metals used include stainless steel, titanium, and cobalt chrome, whereas the plastic used is polyethylene. Various components of a hip implant may be used for a hip replacement surgery. The components used may depend on the extent of damage to the hip joint, and the preference of the orthopedic surgeon performing the procedure.
Components of a Hip Implant
Hip joint is a ball-and-socket joint. The ball or the spherical head of the thighbone (femur) moves inside a cup shaped socket (acetabulum) of the pelvis.
The components of a hip implant replicate the natural shape and structure of the ball-and-socket joint. The components used may depend on the size of the body and vary from patient to patient. A total hip replacement implant has three parts:
- Stem: The stem fits into the femur
- Ball: The ball replaces the spherical head of the femur
- Cup: The cup replaces the worn out hip socket
Types of Hip Implants
Based on the patient’s activity level, any of the following types of hip implants may be used in a hip replacement surgery.
Metal-on-polyethylene implant: The ball is replaced with a metal ball and the socket is replaced with polyethylene or has a polyethylene lining.
Ceramic-on-polyethylene implant: The ball is replaced with a ceramic ball and the socket is replaced with polyethylene or has a polyethylene lining.
Metal-on-metal implant: The ball and socket of the hip joint are replaced with metal prosthesis. Metal-on-metal implants have greater durability compared to metal–on-polyethylene implants.
Ceramic-on-ceramic implant: The ball is replaced with a ceramic ball, and the socket has a ceramic lining. They wear less than metal-on-metal implants, and are most durable among the available hip implants.
Ceramic-on-metal implant: The ball is replaced with a ceramic ball and the socket has a metal lining.
Types of Implant Fixation
Depending on the age and activity level of the patient undergoing hip replacement surgery, an orthopedic surgeon may recommend any of the available three types of implant fixation.
Cemented Fixation: The femoral and acetabular components are held together with special bone cement. The bone cement is made from a special polymer called polymethylmethacrylate (PMMA). Patients can often immediately be full weight bearing and walk after a cemented fixation. Cemented fixation is an option for less active patients. However, too much stress on cemented fixation can lead to fatigue fractures.
Cementless Fixation: Cementless implants are coated with a porous material. They attach to the new bone that grows to the surface of the implant via bone ingrowth. The implant may be fixed using screws or pegs until bone ingrowth. Patients need to limit weight bearing and use crutches or walker following cemented fixation to allow the bone to attach itself to the implant. Cementless fixation is an option for more active patients with good bone quality.
Hybrid Fixation: Hybrid fixation uses a combination of cemented and cementless fixation. The acetabular socket is inserted without cement and the femoral stem is inserted with cement.
The hip joint is a ball and socket joint, where the head of the thigh bone (femur) articulates with the cavity (acetabulum) of the pelvic bone.
Sickle cell disease, a group of disorders that affect the hemoglobin or oxygen carrying component of blood, causes avascular necrosis or the death of bone tissue in the hip due to lack of blood supply.
Avascular necrosis commonly affects the head of the femur. Necrosis leads to tiny cracks on the bone which finally causes the head of the femur to collapse. The condition causes pain due to increased pressure in the blood vessels of the bone marrow at the region of the necrosis.
Early stages of avascular necrosis can be treated by core decompression surgery, which reduces pressure, promotes blood flow and encourages healing of the bone.
Core decompression is indicated in the early stages of avascular necrosis, when the surface of the head is still smooth and round. It is done to prevent total hip replacement surgery, which is indicated for severe cases of avascular necrosis and involves the replacement of the hip joint with an artificial device or prosthesis.
Core decompression is done under spinal or general anesthesia. The patient is placed on their back in supine position. Live X-ray imaging or fluoroscopy is used to guide your surgeon during the procedure.
A small incision is made on your hip and a guide wire is passed from the incision through the neck of the femoral bone to the necrotic area in the femoral head. A hole is then drilled along the wire. The necrotic bone is then removed. This reduces the pressure immediately and creates space for the new blood vessels to grow and nourish the existing bone.
The cavity that is left behind in the bone is sometimes filled with bone graft taken either from another part of your body or a cadaver. Sometimes synthetic bone graft material is used. The incision is then closed with sutures. Another variation of the same surgery involves drilling very small diameter holes from a single point. The surgical wound in this case is very small and may require only a single suture.
After the operation, crutches are to be used for 6 to 12 weeks to prevent weight bearing at the hip joint until the femur bone heals completely. You will be able to resume your regular activities 3 months after the surgery.
The advantages of core decompression include the following:
- Prevents complications of collapse of the femoral head
- Preserves bone of the femur
- Delays the need for total hip replacement where the diseased femur head is replaced with an artificial prosthesis.
Risks and Complications
As with all surgeries, core decompression may be associated with certain complications such as:
- Fracture along the core track
- Perforations in the femoral head
- Deep vein thrombosis
The hip joint is one of the body's largest weight-bearing joints and is the point where the thigh bone (femur) and the pelvis (acetabulum) unite. It is a ball and socket joint in which the head of the femur is the ball and the pelvic acetabulum forms the socket.
The trochanteric bursa is the large sac present above the greater trochanter of the femur.
The iliotibial band is the ligament that crosses the hip joint, runs down the lateral thigh and attaches to the knee; the band helps stabilize and move the joint.
Hip endoscopy is a minimally invasive procedure indicated in the treatment of various disorders of the hip such as external snapping hip syndrome, internal snapping hip syndrome, gluteus medius tears, and greater trochanteric bursitis.
The aim of the procedure is to relieve chronic debilitating hip pain. Portal incisions are one of the most challenging aspects of hip endoscopy. The incision locations depend on the surgeon’s preference and the pathology being treated.
External snapping hip occurs when the IT band snaps over the prominence of the greater trochanter during flexion and extension. During hip endoscopy, a diamond shaped defect is created on the IT band lateral to the greater trochanter and the IT band is released. The diamond shaped defect allows free mobility of the greater trochanter and prevents snapping of the IT band. The surgery is performed outside the hip joint, in the peritrochanteric space.
Internal snapping hip occurs when the iliopsoas tendon snaps over the femoral head, and mostly occurs with hip extension from a flexed position of greater than 90 degrees. Endoscopic treatment involves release of the iliopsoas tendon at the level of the hip joint or at the insertion of the iliopsoas tendon on the lesser trochanter.
Endoscopic procedures use minimally invasive techniques; a smaller incision is placed than the traditional large open incision. Some of the benefits of endoscopic procedures include:
- Minimal trauma to the surrounding tissues
- Shorter recovery time with minimal post-surgical complications
- Greater range of motion with less post-operative pain
Femoroacetabular impingement (FAI) is a condition where the hip bones are abnormally shaped and the ball (femur or thigh bone head) and socket (acetabulum) joint of the hip bones rub against each other due to abnormal contact. Bone spurs form around the femoral head and/or acetabulum preventing smooth gliding movement of these bones against each other. This condition can damage the articular cartilage (smooth cushioning surface of the ball and socket) or cause a tear in the labrum (soft elastic tissue which forms the socket ring) in the hip joint. The progression of this injury to the tissues in the hip joint can result in degenerative joint disease and arthritis.
The two types of hip impingement are pincer and cam impingement. Pincer impingement occurs due to over coverage of the socket, whereas cam impingement occurs when the abnormally shaped femoral head doesn’t fit well in the acetabulum. Sometimes, both types are present together and are called combined impingement.
FAI can be treated with femoroacetabular osteoplasty (FAO), a surgical procedure performed to remove the protruding bony areas of the hip joint, thereby allowing an impingement-free range of motion of the hip.
The goal of FAO involves:
- Reshaping the protruding region of the femur and/or acetabulum
- Repair torn labrum
- Perform arthroscopic microfracture and/or removal of articular cartilage
Osteoplasty for FAI can be performed by open surgical dislocation, arthroscopy, or a mini-open procedure.
Open surgical dislocation
Your doctor will make an incision of about 6 to 10 inches, and cut the upper thigh bone to dislocate the femoral head from the socket so that all the parts of the hip joint can be exposed. The complete dislocation allows repair of the labrum tears and bony abnormalities of the femoral head, and allows intraoperative protection of the blood supply to the hip.
The procedure can be completed in 2-3 hours and requires an overnight hospital stay. It is not recommended in patients with athletic demands, significant hip degeneration or older patients.
Your surgeon will use an arthroscope (instrument consisting of a small camera and lighted device) to visualize and treat the damaged hip joint. Two to four incisions of approximately 1 cm will be made to conduct the procedure. Arthroscopy can be used to treat the various problems associated with FAI such as damaged cartilage, labrum tears and friction between the bones. It can also be used to reshape the femoral head into a round sphere or trim the acetabulum to restore the joint’s smooth movement.
Arthroscopic microfracture can be performed to deliver stem cells into the area of the damaged cartilage to stimulate the growth of healthy cartilage. Without the labral repair and bony decompression, the procedure takes about an hour, whereas conditions requiring labral repair and decompression are performed within 2-4 hours. Arthroscopic procedures require care to avoid blood vessel damage during osteoplasty.
Mini-open surgery combines both open and arthroscopic procedures. Your surgeon will make an incision and insert an arthroscope. A capsulotomy (incision to help visualization and instrument navigation) is performed and the hip is slightly extended to treat the labrum, acetabular rim and internal compartments of the abnormal hip bones using a high-speed or arthroscopic burr. This approach avoids the risk of damage to nerves and the femoral cartilage.
You may experience numbness or tingling after surgery due to anesthesia. The catheter placed for urinary retention will be removed on the next day of the procedure. You will be on overnight intravenous fluids and medications to relieve pain, and on anti-coagulation therapy to prevent clots in the veins after the surgery. On the next day of surgery, you may be recommended for physical therapy following which you can be discharged to home.
After the FAI surgery, you will require 3 to 4 months of rehabilitation to recover and perform activities without obstruction.
Risks and complications
As with any surgical procedure, hip FAO surgery may involve the following potential risks and complications.
- Hip dislocation and instability
- Abnormal formation of bone in the soft tissues
- Nerve injury
- Dead bone at the femoral head
- Femoral neck fracture
- Deep vein thrombosis (blood clots in the veins)
FAO restores physical activity and reduces pain in patients with FAI having minimal or no arthritis.
The hip joint is one of the body's largest weight-bearing joints and is the point where the thigh bone (femur) and the pelvis (acetabulum) unite. It is a ball and socket joint in which the head of the femur is the ball and the pelvic acetabulum forms the socket. The joint surface is covered by a smooth articular cartilage that cushions and enables smooth movements of the joint.
Hip hemiarthroplasty is a surgical technique employed to treat hip fractures. In this procedure, only one half (ball section) of the hip joint is substituted by a metal prosthesis.
The procedure is performed under general anesthesia. An incision is made along the outer aspect of the affected hip. The surgeon gains access to the hip joint and the head of the femur is removed using surgical instruments and prepared to accept the prosthesis. The stem of the metal prosthesis is placed inside the femoral bone. The surgeon now connects the metal ball that forms the femoral head. The stem prosthesis can be press-fit in patients with a strong, healthy bone or cemented in cases of weak, osteoporotic bone. The method of implantation depends on the patient’s age and condition of the bone. At the end of the procedure, the incisions are closed with sutures and a dressing is applied.
The post-procedural instructions to be followed hip hemiarthroplasty include:
- You will be prescribed medications to reduce pain and inflammation.
- Crossing your legs should be avoided.
- Avoid lifting of heavy objects.
- Avoid bending and twisting your hip. Instead use grabbers to pick the things.
- Avoid standing for long hours.
- Use an elevated toilet seat.
- Avoid sitting on low chairs.
- Your surgeon may recommend physical therapy to strengthen the joint and the muscles and to help restore mobility to the hip joint.
Complications of hip hemiarthroplasty include infection, dislocation, deep vein thrombosis, loosening of the prosthesis, and failure to relieve pain. Discuss with your surgeon if you have concerns regarding hip hemiarthroplasty surgery.