Hip and Knee Replacement

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In hip and knee replacement surgeries, new implants composed of materials like ceramic, metal, and plastic are used to replace the worn-out bone and cartilage covering your hip or knee joint. Prosthetics for the knee and hip are made of materials that are relatively comparable.

The overall number of hip replacement surgeries carried out annually in the US has been continuously rising for the past 20 years. It is important for patients considering hip or knee replacement surgery to obtain information from reliable sources about which material the prosthesis is used in their bodies. (1)

According to Harvard expert Dr. Donald T. Reilly, Hip replacement is a much less painful surgery compared to others. After people use crutches for a while, their hips start to feel normal. But it can take six months to a year to heal after total knee surgery, and it's common for the knee to feel normal even then. (2)

Why you shouldn't delay hip or knee replacement surgery

Definition and Overview

Hip and knee replacement surgery is an orthopedic procedure performed to replace damaged or infected joints with artificial prosthetic implants. A knee replacement, often known as a total knee replacement or knee arthroplasty, is a treatment to repair an arthritis-damaged knee. The kneecap and the ends of the bones that make up the knee joint are sealed with plastic and metal parts. For someone with severe arthritis or a serious knee injury, this surgery might be an option. The main objective of knee replacement surgery is to resurface the damaged parts of the knee joint and reduce knee pain that cannot be managed with other treatments. (3)

Hip replacement surgery, commonly known as hip arthroplasty, is performed to treat hip pain. Artificial implants are used in this procedure to replace a portion of the hip joint. A ball and a socket form the hip joint. One or both portions of the hip are replaced during hip replacement surgery. The procedure's goal is to reduce the pain so that the patient can continue everyday activities and exercise. (4)


Hip and knee replacement procedures can be defined as surgical interventions that involve replacing damaged or diseased joints with artificial implants. Typical procedures for hip and knee replacements include:

  • Total knee replacement

It involves replacing the entire knee joint surface with artificial components

  • Partial knee replacement

This procedure is performed when only one compartment of the knee joint is affected by arthritis or damage.

  • Total hip replacement 

THR ( also known as total hip arthroplasty) involves replacing the entire hip joint with artificial components.

  • Partial hip replacement

Partial hip replacement, another name for Hemiarthroplasty, is a surgical treatment that includes replacing only one component of the hip joint while leaving the other intact.

  • Minimally invasive hip replacement

Minimally invasive hip replacement is a surgical procedure that uses smaller incisions and special tools to minimize tissue damage and promote faster healing.

  • Traditional hip replacement

When performing a traditional hip replacement, the surgeon often accesses the hip from the side (lateral approach) or the rear (posterior approach) using a single, broad incision. (5,6)


A doctor may recommend surgery if there is significant discomfort, inflammation, and damage to the hip or knee as a result of conditions such as:

  • Osteoarthritis (most common)
  • rheumatic joint inflammation
  • Osteonecrosis (avascular necrosis)
  • Injury, such as a hip fracture
  • Tumor in the hip joint
  • Stiff and swollen knees
  • pain throughout the day
  • Difficulty walking, descending, or climbing stairs
  • Knee cartilage damage
  • Rubbing of the bones of the joint against each other (7)

Risks and Side Effects

Each surgical procedure carries its own risks and side effects. Likewise, hip and knee replacements carry certain risks and potential complications. For patients, it is important to know and be aware that these risks and side effects are relatively rare. Some potential risks and side effects associated with hip and knee replacement procedures include:

  • Bleeding
  • Infection
  • Leg length discrepancy
  • Injury to nearby nerves
  • Fracture
  • Dislocation
  • Loosening or wearing out of the prosthesis
  • Unrelieved joint pain
  • Blood clots in the legs or lungs
  • Fracture
  • Continued pain or stiffness

Additionally, if bone marrow fat enters the bloodstream, an embolism (obstruction) may occur in extremely rare instances of bone surgery, especially when cement is used. A fat embolism can make a heart attack or stroke more likely. 

The replacement knee joint may become loose, dislodge, or not work as designed. In the future, the joint can require replacement once more. Injuries to the nerves or blood vessels near the surgical site may result in weakness or numbness. Depending on the patients' individual medical conditions, there can be additional dangers. (8,9)

Post-Procedure and Follow-up

The patient is transported to the recovery room for monitoring after the procedure. After that, the patient is taken to the hospital room once his/her breathing, pulse, and blood pressure return to normal. 

Both of these operations often necessitate a few days in the hospital. It is also important to start moving the new joint after surgery. Immediately after the surgery, a physiotherapist meets with the patient and plans an appropriate exercise program. A continuous passive motion (CPM) machine may be used to begin physical therapy. This machine moves the new knee joint through its range of motion while the patient is resting in bed. (10)


It is crucial to keep the surgical site dry and clean after the patient goes home to aid in the recovery process. Stitches or surgical staples are removed during the follow-up visit. It may be desirable to apply ice at intervals to reduce swelling. For pain, a pain reliever can be taken as recommended by the doctor. Only recommended medications should be taken, as aspirin or some other pain relievers can increase the likelihood of bleeding. 


Hip and knee replacements typically last 20 years or longer. The patient can increase the implant's longevity by regularly doing low-impact activity, avoiding high-impact exercise (like jogging), and taking safety precautions to reduce falls. A revision may be required in the future to replace the socket as well if only the ball portion of the hip was replaced during the initial procedure. (11)

Related Procedures

  • 1- American Associations of Hip and Knee Surgeons. What are Hip and Knee Replacement Implants Made Of? (https://hipknee.aahks.org/what-are-hip-and-knee-replacement-implants-made-of/)

    2- Harvard Health Publishing. Harvard expert: What you can expect from knee and hip surgery (https://www.health.harvard.edu/healthbeat/harvard-expert-what-you-can-expect-from-knee-and-hip-surgery

    3,5,8,10- Johns Hopkins Medicine. Knee Replacement Surgery Procedure. (https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/knee-replacement-surgery-procedure

    4,6,7,9,11- Johns Hopkins Medicine. Hip Replacement Surgery. (https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/hip-replacement-surgery