Knee and Hip Replacement Surgery: Complete Guide

What Is Joint Replacement Surgery?

Joint replacement surgery, also called arthroplasty, is a procedure where damaged joint surfaces are removed and replaced with artificial components made of metal, plastic, or ceramic. The goal is to relieve pain, restore function, and improve quality of life when conservative treatments have failed.

Joint replacement surgery represents one of the most significant advances in modern orthopedic medicine. The procedure involves removing damaged cartilage and bone from the joint and replacing these surfaces with precisely engineered artificial components. These implants are designed to replicate the natural movement of a healthy joint while eliminating the painful bone-on-bone contact that occurs with severe arthritis.

The development of joint replacement surgery has revolutionized the treatment of arthritis and joint injuries. Since the first successful hip replacement was performed in the 1960s by Sir John Charnley, surgical techniques, implant materials, and post-operative care have improved dramatically. Today, more than two million joint replacement procedures are performed worldwide each year, with outcomes that would have seemed remarkable just a few decades ago.

Modern joint replacement surgery benefits from advances in materials science, surgical instrumentation, and anesthesia. Computer-assisted surgery and robotic systems now help surgeons achieve more precise implant placement. Improved pain management protocols allow patients to begin walking within hours of surgery, and enhanced recovery programs have shortened hospital stays from weeks to just a few days.

Types of Joint Replacement Procedures

Joint replacement surgery encompasses several different procedures, each designed to address specific conditions and joint areas. Understanding the differences helps patients make informed decisions about their care.

• Total Knee Replacement (TKR): All three compartments of the knee are resurfaced with metal and plastic components
• Partial Knee Replacement: Only the damaged compartment is replaced, preserving healthy bone and ligaments
• Total Hip Replacement (THR): The femoral head and acetabulum are replaced with artificial components
• Hip Resurfacing: The femoral head is capped rather than removed, preserving more bone
• Meniscus Surgery: Repair or removal of damaged meniscal cartilage in the knee
• ACL Reconstruction: Replacement of a torn anterior cruciate ligament with a graft

When Is Knee or Hip Replacement Surgery Needed?

Joint replacement surgery is typically recommended when conservative treatments fail to provide adequate pain relief after at least 6 months, and the patient has significant pain affecting daily activities with X-ray evidence of moderate to severe joint damage. The decision is made jointly between patient and surgeon.

The decision to proceed with joint replacement surgery is never taken lightly. It requires careful consideration of the patient's symptoms, functional limitations, imaging findings, and response to non-surgical treatments. Most orthopedic surgeons recommend trying conservative treatments for at least six months before considering surgery, unless the joint damage is severe or rapidly progressing.

Pain is usually the primary reason patients seek joint replacement. However, it's not just about the presence of pain but how that pain affects daily life. When joint pain prevents you from sleeping, walking reasonable distances, climbing stairs, or performing normal activities, it may be time to discuss surgical options with your doctor.

X-rays and other imaging studies provide objective evidence of joint damage. Surgeons look for signs such as joint space narrowing (indicating cartilage loss), bone spurs (osteophytes), bone-on-bone contact, and changes in bone density. These findings, combined with the patient's symptoms and functional status, help determine whether surgery is appropriate.

Indications for Knee Replacement

Knee replacement surgery is most commonly performed for osteoarthritis, but several other conditions may warrant this procedure. Understanding these indications helps patients recognize when they might benefit from surgical consultation.

Osteoarthritis remains the leading cause of knee replacement surgery worldwide. This degenerative condition involves the gradual breakdown of articular cartilage, leading to pain, stiffness, and loss of function. When cartilage wears away completely, the resulting bone-on-bone contact causes severe pain and joint damage.

Rheumatoid arthritis and other inflammatory conditions can also severely damage the knee joint. Unlike osteoarthritis, which typically affects older adults, inflammatory arthritis can affect patients of any age and may cause more rapid joint destruction. Post-traumatic arthritis, which develops after significant knee injuries, is another common indication for surgery, particularly in younger patients.

Indications for Hip Replacement

Hip replacement surgery addresses conditions affecting the ball-and-socket joint between the femur and pelvis. Like knee replacement, osteoarthritis is the most common indication, but several other conditions may necessitate surgery.

Hip fractures, particularly fractures of the femoral neck in elderly patients, often require hip replacement rather than fracture repair. This is because the blood supply to the femoral head can be disrupted by these fractures, leading to avascular necrosis if the fracture is simply fixed. Hip replacement provides a more reliable outcome in these cases.

Avascular necrosis (also called osteonecrosis) occurs when the blood supply to the femoral head is interrupted, causing the bone to die. This condition can result from hip fractures, dislocations, long-term corticosteroid use, or certain medical conditions. When avascular necrosis progresses to collapse of the femoral head, hip replacement is usually the best treatment option.

What Are the Different Types of Knee and Hip Surgery?

Joint surgery ranges from minimally invasive arthroscopic procedures for meniscus and ACL injuries to major reconstructive procedures like total joint replacement. Options include partial replacement for localized damage and total replacement for widespread arthritis.

The spectrum of knee and hip surgery extends from relatively minor arthroscopic procedures to complex revision surgeries. Understanding these options helps patients engage in informed discussions with their surgical team about the most appropriate treatment for their specific condition.

Total Knee Replacement

Total knee replacement, also called total knee arthroplasty, involves resurfacing all three compartments of the knee: the medial (inner), lateral (outer), and patellofemoral (kneecap) compartments. This procedure is appropriate when arthritis affects multiple areas of the knee.

During the procedure, the surgeon removes damaged cartilage and a small amount of underlying bone from the femur (thighbone) and tibia (shinbone). The bone surfaces are then shaped to accept the artificial components. A metal cap is placed on the end of the femur, and a metal tray with a plastic insert is attached to the top of the tibia. The undersurface of the kneecap may also be resurfaced with plastic.

Modern total knee replacement techniques have evolved significantly. Many surgeons now use approaches that preserve the cruciate ligaments, maintain natural knee kinematics, and minimize soft tissue disruption. These advances have improved outcomes and accelerated recovery. The average total knee replacement surgery takes 1-2 hours, and most patients are walking with assistance the same day.

Partial Knee Replacement

Partial (unicompartmental) knee replacement offers an alternative for patients whose arthritis is limited to one compartment of the knee. This procedure replaces only the damaged portion while preserving healthy cartilage, bone, and all four knee ligaments.

The advantages of partial knee replacement include a smaller incision, less bone removal, faster recovery, more natural feeling knee, and potentially better range of motion compared to total replacement. However, not all patients are candidates for this procedure. Ideal candidates have arthritis limited to one compartment, intact cruciate ligaments, good range of motion, and mild to moderate deformity.

Partial knee replacement may eventually require conversion to total knee replacement as arthritis progresses to other compartments. Studies show that approximately 80-90% of partial knee replacements are still functioning well at 10 years, though long-term data beyond 15-20 years is still being collected.

Total Hip Replacement

Total hip replacement involves replacing both the ball (femoral head) and socket (acetabulum) of the hip joint. The femoral head is removed and replaced with a metal or ceramic ball attached to a stem that fits into the hollow center of the femur. The damaged cartilage surface of the acetabulum is removed and replaced with a metal cup, lined with plastic, ceramic, or metal.

Hip replacement surgery can be performed through several different surgical approaches, each with its advantages and disadvantages. The posterior approach has traditionally been most common, offering excellent visualization and versatility. The anterior approach, which works between muscles rather than cutting through them, has gained popularity for its potential to enable faster recovery. The lateral and anterolateral approaches each have their proponents as well.

Component fixation can be achieved with or without cement. Cemented components use a special bone cement (polymethylmethacrylate) to bond the implant to bone. Uncemented (press-fit) components have porous surfaces that allow bone to grow into the implant over time. The choice depends on patient factors including bone quality, age, and surgeon preference.

Meniscus Surgery

The menisci are C-shaped pieces of cartilage that act as shock absorbers between the femur and tibia. Meniscal tears are among the most common knee injuries, particularly in athletes and older adults with degenerative changes.

Meniscus surgery is typically performed arthroscopically through small incisions using a camera and specialized instruments. The two main types of meniscus surgery are repair and partial meniscectomy (removal). Whenever possible, surgeons try to repair the meniscus, as removing meniscal tissue increases the risk of developing arthritis over time.

Not all meniscal tears require surgery. Many tears, particularly degenerative tears in older adults, can be managed successfully with physical therapy and anti-inflammatory medications. Surgery is typically recommended for tears that cause mechanical symptoms (locking, catching) or persistent pain despite conservative treatment.

ACL Reconstruction

The anterior cruciate ligament (ACL) is a key stabilizer of the knee, preventing the tibia from sliding forward relative to the femur. ACL tears commonly occur during sports that involve sudden stops, direction changes, or jumping. Unlike some ligaments, the ACL has poor healing capacity and usually requires surgical reconstruction to restore stability.

ACL reconstruction involves replacing the torn ligament with a graft. Common graft choices include patellar tendon (from the patient's own knee), hamstring tendons, quadriceps tendon, or allograft (donor tissue). Each graft type has advantages and disadvantages in terms of strength, healing, and donor site morbidity.

Modern ACL reconstruction has excellent outcomes, with most patients returning to their previous activity level. However, recovery is lengthy, typically requiring 9-12 months before return to high-level sports. Rehabilitation is crucial for success, focusing on regaining range of motion, strength, and neuromuscular control before returning to activity.

How Should You Prepare for Joint Replacement Surgery?

Preparation for joint replacement includes completing pre-operative medical assessments, starting physical therapy exercises 2-4 weeks before surgery, preparing your home for safe mobility, arranging post-operative support, and following instructions about medications and fasting.

Proper preparation for joint replacement surgery can significantly impact your outcome and recovery. The weeks before surgery offer an opportunity to optimize your health, strengthen the muscles around your joint, and prepare your home and support system for the post-operative period.

Pre-operative medical evaluation ensures you are healthy enough for surgery and helps identify any conditions that might increase surgical risk. Your surgeon will order blood tests, electrocardiogram, and possibly other studies depending on your medical history. You may need clearance from your primary care physician or specialists if you have heart disease, diabetes, or other chronic conditions.

Medications require careful review before surgery. Blood thinners, including aspirin and certain supplements, may need to be stopped to reduce bleeding risk. However, never stop any medication without consulting your healthcare team, as some medications (like heart or blood pressure medications) should be continued. Your surgical team will provide specific instructions about which medications to stop, when to stop them, and when to restart.

Pre-habilitation Exercises

Pre-habilitation (prehab) refers to physical therapy exercises performed before surgery to improve strength and function. Research shows that patients who participate in prehab programs have better surgical outcomes, shorter hospital stays, and faster recovery compared to those who don't.

A typical prehab program begins 2-4 weeks before surgery and focuses on strengthening the muscles around the affected joint. For knee replacement, this includes quadriceps, hamstring, and hip abductor strengthening. For hip replacement, emphasis is placed on hip flexor, abductor, and extensor muscles. Your physical therapist can design a program appropriate for your current level of function.

Beyond specific exercises, general physical conditioning is beneficial. Walking, swimming, or stationary cycling can improve cardiovascular fitness, which helps with surgery and recovery. Weight loss, if indicated, can also reduce surgical risk and improve long-term outcomes. Even modest weight loss of 5-10% can make a meaningful difference.

Preparing Your Home

Your home environment plays a crucial role in safe recovery. Before surgery, assess your living space and make modifications to reduce fall risk and facilitate mobility with assistive devices.

Remove loose rugs, electrical cords, and clutter from walkways. Ensure adequate lighting, especially in hallways and bathrooms. Install grab bars in the bathroom near the toilet and shower. Consider a raised toilet seat and shower bench or chair. If possible, set up your recovery area on the main floor to avoid stairs initially.

Stock up on supplies before surgery: easy-to-prepare meals, medications, ice packs, and personal care items. Arrange furniture so you can sit down and stand up easily. Place commonly used items at waist level to avoid bending or reaching. Having your home prepared before surgery allows you to focus on recovery rather than logistics.

What Happens During Joint Replacement Surgery?

Joint replacement surgery typically takes 1-2 hours under general or regional anesthesia. The surgeon removes damaged bone and cartilage, shapes the bone to accept artificial components, tests the fit and function, then closes the incision. Most patients are walking within 24 hours.

Understanding what happens during surgery can help alleviate anxiety and prepare you for the experience. While specific techniques vary between surgeons and institutions, the general process follows similar steps.

Anesthesia options include general anesthesia (where you are completely asleep) or regional anesthesia (spinal or epidural block that numbs the lower body while you remain awake or lightly sedated). Regional anesthesia has become increasingly popular for joint replacement because it can reduce blood loss, provide better post-operative pain control, and avoid some complications associated with general anesthesia. Your anesthesiologist will discuss the best option for your situation.

Once anesthesia takes effect, the surgical team positions you appropriately and prepares the skin with antiseptic solution. The surgeon makes an incision to access the joint. The size and location of the incision depends on the surgical approach used. Minimally invasive techniques use smaller incisions but may not be appropriate for all patients.

Knee Replacement Procedure

For total knee replacement, the surgeon typically makes an incision over the front of the knee. The kneecap is moved aside to expose the joint. Specialized guides and cutting instruments are used to remove precise amounts of bone from the femur and tibia. Some surgeons use computer navigation or robotic assistance to enhance accuracy.

Trial components are placed to check fit, alignment, and range of motion. The surgeon tests the knee through its full range of motion and makes any necessary adjustments. Once satisfied with the fit and function, the final implant components are placed and secured with or without bone cement. The incision is closed in layers, and a sterile dressing is applied.

Hip Replacement Procedure

Hip replacement begins with an incision that varies in location depending on the surgical approach. The surgeon dislocates the hip and removes the femoral head (the ball portion). The acetabulum (socket) is prepared with specialized reamers to create a hemispherical cavity that will accept the cup component.

The femoral canal is prepared with rasps of increasing size until it matches the planned stem size. Trial components are tested to check leg length, stability, and range of motion. The surgeon tests the hip in various positions to ensure it doesn't dislocate. Final components are implanted, the hip is reduced (put back in place), and the incision is closed.

What Is the Recovery Process After Joint Replacement?

Recovery from joint replacement involves immediate post-operative mobilization within 24 hours, 1-3 days hospital stay, 6-12 weeks of outpatient physical therapy, and full recovery in 3-6 months. Following your rehabilitation program is crucial for optimal outcomes.

Recovery from joint replacement surgery follows a predictable progression, though individual experiences vary based on factors including age, overall health, and commitment to rehabilitation. Modern enhanced recovery protocols have significantly shortened the recovery timeline compared to techniques used even a decade ago.

The immediate post-operative period focuses on pain management, preventing complications, and initiating mobility. Most patients receive a combination of medications to control pain, including nerve blocks, non-opioid pain relievers, and opioids as needed. Blood clot prevention measures, including blood thinners and compression devices, are started immediately.

Physical therapy begins on the day of surgery or the following morning. Early mobilization is one of the most important advances in joint replacement recovery. Getting up and walking, even short distances with assistance, reduces the risk of blood clots, maintains muscle strength, and promotes healing. Most patients are surprised by how much they can do so soon after surgery.

Hospital Recovery

Hospital stays for joint replacement have shortened dramatically. Most patients now go home within 1-3 days after surgery, compared to weeks in hospital just a generation ago. Some patients, particularly those undergoing hip replacement, may even go home the same day as surgery in carefully selected cases.

Before discharge, you must meet certain criteria demonstrating you can safely recover at home. These typically include adequate pain control with oral medications, ability to walk safely with an assistive device, ability to perform basic self-care, understanding of activity restrictions and warning signs, and a safe home environment with appropriate support.

Hospital physical therapists teach you essential skills including how to get in and out of bed, how to use your walker or crutches safely, how to navigate stairs if necessary, and specific exercises to perform at home. Following these instructions carefully during the early recovery period lays the foundation for long-term success.

Home Recovery

The first few weeks at home require patience and dedication to your recovery program. Pain and swelling are normal and gradually improve over time. Ice application, elevation, and prescribed medications help manage these symptoms. Most patients find that pain medication needs decrease significantly within the first 1-2 weeks.

Activity restrictions during early recovery protect the healing joint. Hip replacement patients must follow hip precautions to prevent dislocation, which may include avoiding crossing legs, bending past 90 degrees, and turning the foot inward. Knee replacement patients focus on achieving full extension (straightening) and adequate flexion (bending). Your surgical team will provide specific guidance for your situation.

Outpatient physical therapy typically begins 1-2 weeks after surgery and continues for 6-12 weeks. Sessions focus on progressive strengthening, range of motion exercises, gait training, and functional activities. Your therapist will advance your program as you achieve milestones, gradually increasing the challenge until you return to your desired activity level.

Long-term Recovery

Full recovery from joint replacement typically takes 3-6 months, though improvement can continue for up to a year. Most patients return to sedentary work within 2-4 weeks and physically demanding work within 3-6 months. Driving is typically permitted 4-6 weeks after surgery, depending on which leg was operated and whether you drive a manual or automatic transmission.

Return to recreational activities follows a progressive timeline. Walking and swimming can usually resume early in recovery. Golf and cycling are typically permitted at 3-4 months. Higher-impact activities like tennis or hiking may take 6 months or longer. Some activities, particularly those with high impact or risk of falls, may need to be permanently modified.

What Are the Risks and Complications of Joint Replacement?

While joint replacement is generally safe with over 95% success rates, potential risks include infection (1-2%), blood clots (1-2%), implant loosening, nerve injury, leg length discrepancy, and the need for revision surgery. Modern techniques and protocols have significantly reduced these risks.

Like any major surgery, joint replacement carries risks that patients should understand before proceeding. However, it's important to keep these risks in perspective: serious complications are uncommon, and for most patients, the benefits of surgery far outweigh the risks.

Infection is one of the most concerning complications, occurring in approximately 1-2% of cases. Surgeons take extensive precautions to prevent infection, including antibiotic prophylaxis, sterile techniques, and special operating room protocols. Most infections occur in the first few weeks after surgery, but late infections can occur even years later, often from bacteria entering the bloodstream from dental procedures or other sources.

Blood clots (deep vein thrombosis) can form in the leg veins after joint replacement due to immobility and the body's response to surgery. These clots can be dangerous if they travel to the lungs (pulmonary embolism). Prevention measures including blood thinners, compression devices, and early mobilization have significantly reduced this risk.

Short-term Complications

Immediate post-operative complications, while uncommon, can include wound healing problems, nerve or blood vessel injury, and dislocation (particularly after hip replacement). Surgeons take care to protect important structures during surgery, but some temporary numbness or weakness around the incision is common and usually resolves over time.

Hip dislocation is a specific concern after hip replacement, occurring in approximately 1-3% of cases. Certain surgical approaches have lower dislocation rates than others. Patients must follow hip precautions during early recovery to minimize this risk. If dislocation occurs, it can often be treated without further surgery, though some cases require revision.

Long-term Complications

Long-term complications primarily involve the implant itself. Loosening occurs when the bond between the implant and bone fails, causing pain and instability. Modern implants and techniques have significantly reduced loosening rates, but it remains the most common reason for revision surgery in the long term.

Wear of the plastic bearing surface can occur over many years, releasing particles that can cause bone loss around the implant. Newer materials, including highly cross-linked polyethylene and ceramic bearings, have dramatically improved wear resistance. Nevertheless, even the best implants are mechanical devices that may eventually need replacement.

What Are the Expected Outcomes After Joint Replacement?

Joint replacement has excellent outcomes, with over 95% of patients reporting significant pain relief and improved function. Modern implants last 15-25 years in most patients, and satisfaction rates are among the highest of any surgical procedure.

Joint replacement surgery consistently achieves high patient satisfaction and excellent functional outcomes. For patients who have suffered with arthritis pain and disability, the improvement can be life-changing, enabling return to activities they had given up and improving overall quality of life.

Pain relief is typically dramatic. Most patients report significant improvement within weeks of surgery, with continued improvement over the following months as they rehabilitate. Studies show that 90-95% of patients report substantial pain relief after joint replacement. Many describe being able to sleep through the night for the first time in years.

Functional improvement follows pain relief. Patients typically regain the ability to walk longer distances, climb stairs, and perform daily activities without significant discomfort. Range of motion improves, though it may not return to completely normal. Most patients achieve functional motion that allows them to perform all normal activities.

Implant Longevity

Modern joint replacement implants are remarkably durable. National joint registries, which track outcomes for hundreds of thousands of patients, provide reliable data on implant survival. These registries consistently show that 85-90% of knee replacements and 90-95% of hip replacements are still functioning well at 15-20 years.

Several factors influence how long an implant will last. Patient factors include weight, activity level, bone quality, and overall health. Surgical factors include implant selection, surgical technique, and component positioning. Implant factors include bearing surface materials and design features.

When revision surgery becomes necessary, it can be performed successfully, though the procedure is more complex than the primary surgery. Modern revision techniques have improved significantly, and good outcomes can still be achieved. However, avoiding revision by optimizing the primary surgery and following appropriate activity guidelines is always preferable.

What Are the Alternatives to Joint Replacement Surgery?

Non-surgical alternatives include physical therapy, weight management, anti-inflammatory medications, corticosteroid injections, hyaluronic acid injections, and regenerative therapies like PRP. These treatments can effectively manage symptoms for many patients, though they don't reverse joint damage.

Joint replacement is not the only option for managing arthritis, and it should generally be considered only after conservative treatments have been tried. Many patients can achieve satisfactory symptom control without surgery, at least for a period of time.

Physical therapy remains a cornerstone of arthritis management. Strengthening the muscles around a damaged joint reduces stress on the joint itself and improves stability. Flexibility exercises maintain range of motion. Aquatic therapy provides strengthening benefits with reduced joint stress. A well-designed physical therapy program can significantly reduce pain and improve function.

Weight management is particularly important for knee arthritis. Each pound of body weight translates to approximately 4-6 pounds of force across the knee during walking. Even modest weight loss can meaningfully reduce joint stress and symptoms. Combined with exercise, weight management forms the foundation of conservative arthritis treatment.

Medications and Injections

Anti-inflammatory medications, both over-the-counter (like ibuprofen and naproxen) and prescription-strength, can help manage arthritis pain. Acetaminophen (Tylenol) provides pain relief without anti-inflammatory effects and may be appropriate for some patients. Topical treatments, including anti-inflammatory gels and capsaicin cream, offer localized relief with minimal systemic effects.

Corticosteroid injections deliver powerful anti-inflammatory medication directly into the joint. These injections can provide significant relief lasting weeks to months, though the effect typically diminishes with repeated injections. Most orthopedic surgeons limit the frequency of injections to avoid potential negative effects on cartilage.

Hyaluronic acid injections (viscosupplementation) aim to supplement the joint's natural lubricating fluid. While research on their effectiveness is mixed, some patients experience meaningful relief. These injections are generally very safe, making them a reasonable option for patients seeking to delay or avoid surgery.

Emerging Therapies

Regenerative medicine approaches, including platelet-rich plasma (PRP) and stem cell injections, have generated considerable interest. PRP uses concentrated platelets from the patient's own blood to potentially stimulate healing. While some patients report benefit, high-quality evidence supporting these treatments remains limited. They are generally not covered by insurance.

Joint-preserving surgical options may be appropriate for some patients, particularly younger individuals with localized cartilage damage. Procedures include arthroscopic debridement, microfracture, osteochondral grafting, and osteotomy (realignment of the bone to shift weight away from damaged areas). These procedures can delay or potentially avoid the need for joint replacement in selected patients.