Total Knee Replacement: Recommended Guidelines From the American Physical Therapy Association

Do I Need a Total Knee Replacement?

Not everyone who has knee pain needs a total knee replacement.  Many times, your pain can be resolved by conservative treatments that improve the strength of the surrounding musculature, increase the mobility of the joint structures, correct for an irregular walking pattern or decrease the inflammation and pain present in the knee.  After reviewing the radiographs of your knee, an orthopedic doctor may recommend surgery if you also have the following presentation:

1. Severe knee pain or stiffness that limits everyday activities, also known as activities of daily living (ADLs).  These can include walking, stairs, and getting in and out of chairs.  You may be using a cane or walker
2. Moderate or severe knee pain while resting
3. Chronic knee inflammation and swelling that does not improve with rest or medications
4. Knee deformity – bowing in or bowing out of the knee.
5. Failure to improve through other conservative treatments such as anti-inflammatory medications, cortisone injections, lubricating injections, physical therapy, or other surgeries.

What is a Total Knee Replacement?

Knee replacement is needed due to the presence osteophytes and cartilage breakdown that exposes the underlying bone.  A knee replacement is actually a resurfacing of the bones that make up the knee joint.  These bones include the femur, tibia, fibula, and patella, however nothing is done to the fibula during the surgery.  The procedure is fairly straight forward and typically involves 4 steps.

1. Prepare the Bone.  Your surgeon removes the damaged cartilage surfaces at the ends of the femur and tibia along with a small amount of underlying bone.
2. Positioning of the Metal Implant.  The cartilage and bone that has been removed is replaced with metal components to recreate the surface of the joint.  These metal parts are cemented or “press-fit” into the bone.
3. Resurfacing of the Patella.  The undersurface of the patella, or kneecap, is cut and resurfaced with a plastic button.  This is not performed with every surgery as your surgeon determines if this is needed.
4. Insertion of a Spacer.  A medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.

Total Knee Replacement Post-Operative Recommendations

According to the Agency for Healthcare Research and Quality there are 790,000 total knee replacements performed in the United States annually.  Recently the American Physical Therapy Association released a research article that reviewed physical therapy guidelines for achieving the best outcomes following surgery.  These guidelines were based on research support and a general consensus on best practices when little or no research was available.  The original article can be found here:  Physical Therapy, pzaa099, https://doi.org/10.1093/ptj/pzaa099.

The strongest recommendation supported by research was for motor function training, i.e. balance, walking, and movement symmetry.  Activities such as balance training, Pilates, and the AlterG treadmill are highly recommended.   Evidence quality: High; Recommendation Strength: Strong.

Moderate recommendations were given for preoperative exercise (Prehab), neuromuscular electrical stimulation, resistance and intensity of strengthening exercises, cryotherapy.  Evidence quality: High; Recommendation Strength: Moderate.

A weak recommendation was given for immediate postoperative knee flexion while at rest.  The researchers also found a moderate recommendation against the use of continuous passive motion (CPM) devices.  CPMs are used for passive mobilization of the knee while the patient is usually in a supine position.

Other Factors Affecting Improvement After Surgery

1. Higher BMI (body mass index) is associated with more postoperative complications and worse postoperative outcomes.
2. Depression is associated with worse postoperative outcomes.
3. Preoperative ROM is positively associated with postoperative ROM but has minimal, if any, effect on physical function and quality of life.
4. Preoperative physical function is positively associated with postoperative physical function.
5. Preoperative strength is positively associated with postoperative physical function.
6. Age is associated with mixed patient-reported, performance-based, and impairment-based outcomes.
7. Diabetes is not associated with worse functional outcomes.
8. A greater degree of comorbidity is associated with worse patient-reported outcomes.
9. Gender is associated with both positive and negative effects on postoperative outcomes.

The therapists at Synergy Health and Wellness follow these guidelines to help you achieve the best outcome possible.