Surgical Complications: Total Hip Replacement
Surgery has the potential to improve the lives of many patients. However, there are inherent risks that are involved with ANY surgical procedure. For patients thinking about hip replacement surgery, it is important to discuss with your surgeon what outcome you can reasonably expect. It is also essential to understand the risks and potential complications associated with a total hip replacement. Complications associated with hip replacement surgery may include:
- Wound healing problems – painful scar
- Superficial wound infection
- Prosthetic infection – deep infection following total hip replacement
- Deep vein thrombosis (blood clot)
- Pulmonary embolism
- Nerve injury/neuritis
- Vascular injury – blood loss
- Leg-length discrepancy (one leg shorter than the other)
- Asymmetric gait
- Recurrent hip dislocation
- Heterotopic ossification (bone forming where it shouldn’t)
- Loosening of the prosthesis
- Peri-prosthetic fracture
Wound Healing Problems – Painful scar
Wound healing problems include scarring and wound breakdown that can lead to infection. When a total hip replacement is performed, there are many layers that the surgeon must cut through in order to access the joint. These include skin, fat, muscle, fascia, tendons and ligaments. After the joint replacement is performed, these pieces need to be repaired and put back into place so they may properly heal.
The disruption that occurs from cutting through these layers can sometimes lead to scar tissue formation as the body repairs itself. This means there is unwanted tissue in and around the incision site, which may cause pain as an unwanted side effect. Fortunately, significant problems with wound healing and painful scar formation are relatively uncommon following hip surgery, except in patients with risk factors.
During surgery, surgeons do their best to minimize the potential for scar tissue formation, by making precise incisions along the tension lines of the skin. The incision will also be as small as possible to decrease disruption of the skin while also allowing for a successful hip replacement. Additionally, scar tissue massage may be recommended post-surgically when appropriate to loosen the tissue in the area, preventing unwanted tissue buildup.
There are many risk factors associated with poor wound healing. Risk Factors include the following:
- A compromised immune system (HIV+, corticosteroid use)
- Use of blood thinners (aspirin, heparin, warfarin)
- Previous surgery
- Older age
It is important to reduce any modifiable risk factors to the extent possible before surgery. This can include controlling blood glucose levels, quitting smoking, optimizing immune function and weight loss.
Superficial wound infection following total hip replacement
A superficial infection at the surgical site occurs due to contamination of the site with bacteria during or after surgery. Superficial infections do not extend down to the prosthetic joint, but they are risk factors for developing a deeper infection if not properly treated. Prolonged oozing from the wound after surgery can make the incision vulnerable to infection. Thus, poor wound healing puts a person at risk for developing a wound infection.
As stated in the wound healing problems section, there are many risk factors that make a person more vulnerable to poor wound healing. Reducing these risk factors as much as possible before surgery, including controlling blood glucose and weight loss, significantly reduces the potential for a wound healing problem.
There are many precautions that are taken in order to minimize the chance of wound infection. Before surgery, the surgeon will often recommend bathing in an antiseptic solution, such as chlorhexidine (Hibiclens), prior to coming in for the procedure. In addition, the surgeon will administer an intravenous antibiotic immediately prior to surgery in order to reduce the likelihood of infection. During surgery, the surgical team takes multiple precautions in order to reduce wound infection. These include properly cleaning and draping the surgical site and maintaining a sterile field. After surgery, sterile dressings are applied to the surgical site to protect the wound from infection while it heals. The surgeon will also provide the patient with wound care instructions to ensure cleanliness of the site.
If a superficial wound infection does occur, it may be treated with antibiotics. In some instances the surgeon may elect to take the patient back to the operating room to clean out (debride) the infection.
Prosthetic infection -Deep infection following total hip replacement
Serious deep infection following hip surgery is not common. Deep infection typically occurs in less than 1-2% of patients undergoing an uncomplicated total hip replacement. If a deep infection occurs in the first few weeks after surgery it will often be treated by washing out the infected hip joint in the operating room and placing the patient on intravenous antibiotics.
If this does not eradicate the deep infection, or if the hip becomes infected more than a few weeks after the original hip replacement it may be necessary to completely remove the infected hip replacement. This is usually done in two stages. The first stage involves removing the infected hip replacement and placing an antibiotic spacer. This is followed by a course of intravenous antibiotics usually lasting about 6 weeks. Once there is evidence suggesting that the infection has been eradicated the surgeon can then progress to the second stage which is to revise the hip by placing a new hip replacement.
In some patients with certain types of infection the surgeon may elect to perform a “one-stage” revision –removing the infected hip replacement; cleaning out the hip joint; and placing a new hip replacement all in one surgery. Needless to say, an infected total hip replacement is an inconvenient and challenging complication. Similar to the risk factors for a wound infection diabetes, a compromised immune system, smoking, and previous infection in the area are common risk factors that increase the possibility that a person will develop a deep infection following a total hip replacement.
More information on the treatment of prosthetic hip joint infections can be found on the Infection Post-Hip Replacement page (https://hipeducation.com/infection-post-total-hip-replacement/)
Patient Education Website : https://www.hopkinsmedicine.org/health/conditions-and-diseases/surgical-site-infections
Deep Vein Thrombosis
A DVT (Deep Vein Thrombosis) is a blood clot in the leg veins, which are the veins that help carry blood back to the heart. DVTs are a potentially serious complication of surgery and are unfortunately more common after hip surgery than other orthopedic procedures. This is because of the location of the hip, the way in which the patient must be positioned on the operating table, and the relative immobilization of patients after their hip surgery.
Symptoms of a DVT after hip surgery range from no symptoms at all to marked swelling and discomfort of the upper leg. Having a blood clot in the leg is a worrisome problem because it may lead to a pulmonary embolism. A pulmonary embolism occurs when a blood clot forms and then breaks away and goes to the lungs -a condition which can be fatal.
Risk factors for a DVT include the three elements described by Virchow in the 1800’s:
- Stasis (blood that does not move freely) such as may occur in a patient who is immobilized on the operating table for a while, or someone who is immobilized in a cast. In both instances, normal lower extremity muscle contracting is decreased. This decreases normal venous blood flow.
- Hypercoagulability of the blood (easy clotting). There can be an inherited tendency for increased blood clotting, so a positive family history of a blood clot may be important. Also smoking, the use of birth control pills, and the presence of certain cancers, can increase a patient’s potential to form blood clots.
- Endothelial (blood vessel) injury. Trauma or surgery may increase blood vessel injury, which in turn can increase the chance of blood clots forming.
Based on Virchow’s Triad, the risk of having a blood clot in the leg is increased with:
- Relative Immobilization (e.g. airplane travel)
- Direct injury to the vessel
- Oral birth control or other hormone use
- Positive family history (first-degree relative)
- Previous history of a blood clot (perhaps the most important risk factor)
Blood clot prevention may include mechanical devices to squeeze the lower leg muscles when patients are under anesthesia and medications to thin the blood (ex. aspirin). Using medications to protect against blood clot formation has its own risks. This type of medication may increase the risk of bleeding, which can in turn increase the risk of wound healing problems and infection. The surgeon should ensure that the choice of blood thinner and dosing schedule is optimal for both preventing DVT while also reducing the risk of wound healing problems.
A pulmonary embolism occurs when a blood clot (DVT) breaks off and goes to the lungs. Pulmonary embolisms reduce the amount of oxygen-rich blood getting to all parts of the body. As such, a pulmonary embolism is a very serious condition and can be potentially fatal.
Given that the relative risk of developing a blood clot is higher after hip surgery than other orthopedic surgeries, blood thinning medications will be prescribed to reduce the risk of blood clot formation after most hip surgeries.
The risk factors for developing a pulmonary embolism are identical to those for developing a deep vein thrombosis. They include the following:
- Having a previous pulmonary embolism or deep vein thrombosis (DVT)
- A first-degree family member who has had a pulmonary embolism
- Oral birth control or other hormone use
- Relative Immobilization (e.g. airplane travel)
- Direct injury to the vessel
Blood clot prevention can include mechanical devices to squeeze the lower leg muscles when patients are under anesthesia or thinning the blood with medications. Using medications to protect against blood clot formation has its own risks. This type of medication may increase the risk of bleeding, which can in turn increase the risk of wound healing problems and infection. The surgeon should ensure that the choice of blood thinner and dosing schedule is optimal for both preventing DVT while also reducing the risk of wound healing problems after surgery.
Nerve Injury / Neuritis
Numbness over the incision is a common occurrence following surgery. However, it is a more serious problem if a nerve that affects muscle or sensory control is injured. This can occur when a nerve is placed under traction (pulled on to help with surgery), or when it is directly injured during the procedure. The risk of nerve injury is relatively low but varies widely in total hip replacements. Overall risk depends heavily on the logistics of the operation, and the nerve that is most likely to be injured depends on the surgical approach. Therefore, it is important for any person contemplating surgery to understand the potential risk of a nerve injury.
Risk factors associated with nerve injury following total hip replacement include:
- Developmental dysplasia of the hip
- Post-traumatic hip arthritis
- History of a previous hip surgery
- Female sex
- Limb lengthening following total hip replacement
- Use of a cement-less surgical technique
- Pre-existing nerve injury of spinal origin
The most common nerve injury associated with total hip replacement is a sciatic nerve injury. The sciatic nerve is the largest nerve in the body, and runs behind the hip joint and along the back of the leg, giving off many branches. Individuals with a sciatic nerve injury may demonstrate numbness, tingling and weakness running down the back or side of the leg. A sciatic nerve injury can also lead to foot drop with walking due to failure of ankle flexion.
If a nerve injury does occur, treatment depends on the symptoms the person is experiencing. Commonly the approach to nerve injuries following hip surgery includes waiting to see if the symptoms resolve as healing continues, bracing and physical therapy. If significant pain is present, the surgeon may consider exploratory surgery to evaluate the source of pain and remove any constrictions due to scar tissue that may be contributing to symptoms. If pain is not a factor, surgery may not be the best course of action.
Some blood loss is expected during a total hip replacement as with most surgical procedures. However, significant injury to blood vessels occurs in less than 1% of total hip replacements. Vascular injuries that occur during surgery may be caused by excessive retraction (pulling) of blood vessels, injuries to blood vessels during bone removal (osteotomy), or other mechanisms that lead to blood vessel injury. A vascular injury can either be due to a direct injury to an arterial blood vessel, or secondary to the formation of a blood clot (thrombotic). Fortunately, both types of injury are uncommon, although in a worst case scenario they can result in loss of blood supply to the lower leg and foot.
Risk factors for developing a vascular injury include:
- Preexisting vascular disease (atherosclerosis)
- Abnormal location of blood vessels
- Revision total hip replacement
Leg-length discrepancy (one leg being shorter than the other)
During a total hip replacement procedure, the surgeon uses many techniques to ensure that leg length is as close as possible between the two sides. The surgeon must consider the length of the prosthetic joint and its proper alignment to achieve this. On occasion, a slight mismatch in leg lengths can occur following surgery. It is worth noting that most humans have a natural difference in leg length by a few millimeters. However, a difference of a few centimeters or more in leg length following surgery can be noticeable.
Leg length discrepancy may lead to pain, instability, a limp, or other potential consequences due to the altered mechanics of walking. Most cases of leg length discrepancy can be managed non-operatively with an assistive device such as a cane, a heel lift, or physical therapy. However, a significant or particularly symptomatic leg length difference may require repeat surgery to correct the problem.
While recovering from hip surgery, patients may walk with an uneven gait that will cause extra loading on other parts of the body such as the knees and low back. This change in gait may lead to irritation to tendons, muscles, and ligaments, which can become painful. The symptoms associated with an uneven gait usually go away after the gait has normalized.
Symptoms that result from an uneven gait can be improved by focused stretching and core strengthening exercises as directed by a surgeon and/or physical therapist during the recovery time. In addition, patients should consider using crutches, a cane or a walker to lessen the severity of the asymmetric gait.
Recurrent hip dislocation
Although uncommon, it is possible for a total hip replacement to pop out of the joint (“dislocate”). When this occurs, patients usually have pain and an inability to bear any weight on the affected leg. The hip joint will typically dislocate “out the back” (posteriorly) or through the front (anteriorly) and usually occurs when the patient positions the hip beyond the range of motion that the hip joint can accommodate. The risk of sustaining a dislocation is higher while the hip is still healing after surgery. This is because the soft tissue surrounding the joint has not completely healed, making the joint less stable and vulnerable to dislocation.
Other risk factors for dislocation of a total hip replacement include a history of previous dislocations, age greater than 70, female sex, and a history of revision total hip replacement surgery. Most dislocated total hip replacements can be treated successfully with a closed reduction (putting the hip back in place) in the emergency room. Recurrent hip dislocations or dislocations secondary to a problem with the prosthesis may require surgery to replace or reposition the prothesis.
In order to prevent this complication, certain movements should be avoided after surgery. These include: deep squatting positions, and crossing the legs at the knees. More information on hip dislocations can be found on the Dislocated Total Hip Replacement page.
Heterotopic ossification (bone formation where it is not supposed to form)
Heterotopic ossification is the formation of bone in abnormal locations (ex. in the muscles around the hip joint) during the total hip replacement healing process. This is a relatively common complication, with varying levels of severity. In its most severe form, heterotopic ossification can significantly limit range of motion of the hip joint, canceling out the therapeutic effects of the hip replacement. This condition may be prevented by use of anti-inflammatory medications, especially in persons who are known to form heterotopic bone or who have significant risk factors. In some instances, revision total hip replacement including removal of the excess bone may be recommended to treat heterotopic ossification.
Risk factors for the development of heterotopic ossification include:
- A history of forming excessive new bone following an injury
- Male sex
- Use of a cemented prothesis
- Certain bone and joint conditions
- Total hip replacement on both hips (bilateral)
Loosening of the prosthesis
Prosthetic loosening occurs when the bond between a prosthetic and the surrounding bone does not form or fails over time. This can occur in either the thigh (femoral) or hip socket (acetabular) prosthetic component. Loosening can be a result of prosthetic joint infection but is more commonly caused by failure of the bone to grow into the prosthesis, or aseptic loosening from osteolysis.
Poor prosthetic placement, inadequate cement fixation when using a cemented prosthetic, or wear of the acetabular lining over time can all cause loosening of a prosthesis. Risk factors, including advanced age, obesity, and being too active too early in the recovery (in prostheses which require the bone to grow into the prosthesis). Loosening results in prosthetic failure and is a leading cause for revision total hip replacement surgery.
Failure of a hip prosthesis occurs for a number of reasons. As stated above, these include prosthetic loosening and deep prosthetic infection. Another important cause of prosthetic failure is a peri-prosthetic fracture, or fracture of the bone surrounding the prosthetic components. This can occur if the bone surrounding the prosthesis becomes weakened via osteoporosis and/or osteolysis. Risk factors for developing a peri-prosthetic fracture include female sex, advanced age, long-term corticosteroid use and history of revision total hip replacement.
Treating a peri-prosthetic fracture often involves open reduction and internal fixation of the fracture as the bone is often in multiple fragments (comminuted). A revision of the hip replacement may also be necessary in some cases.