Hinged Knee Replacement

When knee discomfort becomes severe and begins to disrupt your daily activities, or if it’s accompanied by swelling, tenderness, or redness, it’s crucial to seek medical attention.

At Complete Orthopedics, our team of specialized orthopedic knee physicians focuses on treating knee pain, offering both non-surgical and surgical solutions. We’re here to evaluate your symptoms, diagnose the issue, and recommend the most suitable treatment plan, including surgical intervention if necessary.

With locations in New York City and Long Island, and privileges in six hospitals, we’re fully equipped to deliver advanced knee surgery and comprehensive orthopedic care. To schedule an appointment with one of our orthopedic surgeons, you can conveniently book online or contact us by phone today.

Explore the common causes and treatment options for knee pain, and discover when surgical intervention becomes the optimal choice.

Overview 

Imagine the intricate machinery of your knee joint—ligaments, cartilage, bones—working seamlessly to allow you to walk, run, and move freely. But what happens when this intricate system breaks down due to injury, arthritis, or other medical conditions? This is where knee replacement surgery comes into play, offering hope for improved mobility and quality of life.

One type of knee replacement surgery, known as hinged knee replacement, is designed to address more complex knee issues. In this guide, we’ll delve into the basics of hinged knee replacement surgery, exploring what it involves, who it’s for, its benefits, and potential risks.

 

Symptoms

A person who might need a hinged knee replacement typically experiences significant knee pain and mobility issues due to severe knee arthritis, injury, or other conditions affecting the knee joint. Here are some symptoms that may indicate the need for a hinged knee replacement:

Chronic Knee Pain: Persistent and severe knee pain, especially during weight-bearing activities such as walking, climbing stairs, or standing for long periods.

Decreased Range of Motion: Difficulty in fully extending or bending the knee joint, resulting in limited movement and flexibility.

Swelling and Inflammation: Swelling around the knee joint that doesn’t improve with rest, ice, or elevation. Chronic inflammation can indicate underlying joint damage.

Stiffness: Feeling stiffness in the knee joint, especially after prolonged periods of inactivity, such as sitting or sleeping.

Instability: Sensation of the knee giving way or feeling unstable during movement, which can increase the risk of falls.

Difficulty Walking: Persistent difficulty walking due to pain and limited mobility, which may require the use of assistive devices like canes or walkers.

Pain at Rest: Experience of knee pain even while at rest, which can disrupt sleep and daily activities.

Previous Failed Treatments: Inadequate relief from conservative treatments such as physical therapy, medications, corticosteroid injections, or arthroscopic surgery.

X-ray Findings: Radiographic evidence of advanced joint degeneration, bone-on-bone contact, or other structural abnormalities in the knee joint.

Functional Impairment: Significant impairment in performing activities of daily living, recreational activities, or work-related tasks due to knee pain and limitations in movement.

 

Hinged Knee Replacement 

The implants used in a total knee replacement come in different shapes and sizes. The choice of implant used in a total knee replacement depends upon the amount of the bone, quality of the bone, the soft tissue around the knee, any prior surgeries, and also on the medical history of the patient. A hinged knee replacement is a complex knee replacement that requires a special implant with either a hinge or a rotating platform.

During a knee replacement surgery, the surgeon removed the diseased ends of the lower end of the thigh bone and the upper part of the shin bone. The prosthetic replacement of the removed parts recreates the natural knee joint without any disease.

The prosthetic parts are made of metal and high-grade plastic. The femoral and the tibial component are made up of metal while the insert or the spacer is made up of high-grade plastic. The plastic spacer helps in the smooth gliding of the opposing metal surfaces.

A natural knee has motion in the forward and the backward direction as well as a small amount of rotation and side-to-side motion. The thigh bone also slides back on the upper part of the shin bone during bending of the knee which is known as femoral rollback.

Constrain is the ability of the implant to provide stability in forward-backward and side-to-side motion. The constrained implants are needed in the face of bone loss or labor of the ligaments. Implants may be non-constrained, semi-constrained, or fully constrained depending upon the amount of stability they provide.

During a primary knee replacement for arthritis, only the bony ends are diseased and may be associated with mild to moderate deformity. The surgeon removes only the diseased ends and may stretch or release ligaments to correct the deformity.

The bone quantity and the soft tissue support is however adequate to provide stability to the prosthetic joint. Therefore the commonly used knee replacement implants in primary surgery are non-constrained.

All prosthetic implants are limited by their self-life as they wear down over the years. The life of a usual knee implant may be well over more than 20 years and for patients over 60 years of age, they may last their lifetime.

Owing to the success of the surgery, knee replacement is increasingly being performed in the younger age groups. In younger age groups after many years, the implants may need revision surgery. Additionally, revision surgery may be needed in patients with complications of primary surgery such as infection, aseptic loosening, fracture, instability, etc.

During revision surgery, at times there may be an excessive bone loss that may warrant a modular constrained implant. Similarly, in patients with excessive ligament laxity, a constrained implant may be necessary to provide stability. Patients suffering from some kinds of tumors of the bone may require removal of the stabilizing structures of the joint along with the bone tumor. These patients may also require constrained implants.

The constrained implants come in different designs. The originally used hinged constrained implant has been largely superseded by a rotating constrained implant. In a hinged knee replacement implant, there is a connecting rod in between the femoral and tibial components.

The connecting rod has a hinge mechanism to prevent overextension of the joint. This design only allows forward and backward motion and prevents any side to side and rotating motion.

The loss of side to side and rotating motion puts additional stress at the bone-implant interface and may lead to implant loosening or periprosthetic fracture. The rotating constrained implant additionally allows rotating motion about the prosthetic hinge. The hinge is located near the femoral component and a rotating platform is attached to the tibial plate.

The rotating action helps to distribute the stresses more evenly during motion while maintaining stability in the face of bone loss or ligament laxity. The hinged implants are primarily used in revision surgeries and in complex primary knee replacement surgery involving severe deformity or tumors, or salvage surgeries, etc.

The hinged knee replacement implants are also modular that allows the addition of metal wedges or triangles to compensate for bone loss. The stem modularity also allows the addition of long stems to provide stability.

The constrained implants wear out earlier compared to non-constrained but provide excellent stability in difficult cases. The results of constrained hinged knee replacement are better when performed by a surgeon with expertise in performing complex knee replacement surgeries.

 

Recovery and Rehabilitation:

Recovery from hinged knee replacement surgery typically involves a period of rehabilitation to help restore strength, flexibility, and function to the knee. Physical therapy exercises, pain management strategies, and assistive devices such as walkers or crutches may be recommended to aid in recovery.

It’s essential to follow your surgeon’s instructions carefully during the recovery process to ensure the best possible outcome. This may include attending follow-up appointments, adhering to activity restrictions, and practicing proper wound care.

 

Conclusion:

Hinged knee replacement surgery is a valuable option for individuals with complex knee problems that cannot be effectively treated with conservative measures or traditional knee replacement surgery. By incorporating a specialized hinge mechanism, this procedure offers enhanced stability, improved range of motion, and pain relief for eligible candidates.

If you’re experiencing significant knee pain, stiffness, or instability, it’s essential to consult with a qualified orthopedic surgeon to explore your treatment options. With advances in surgical techniques and implant technology, hinged knee replacement offers hope for improved mobility and quality of life for those in need.