The Arthritic Knee
The causes of OA of the knee are multiple and include aging (wear and tear), obesity, and previous knee trauma or surgery. OA affects usually the medial compartment of the knee, and as the bone wears away medially a varus or bowlegged appearance develops. Much less frequently patients develop lateral compartment OA that results in a valgus or knock-kneed deformity.
The most frequently cited cause of OA of the knee is older age, with the accumulation of years of wear-and-tear trauma on the joint, but other risk factors have been identified.
Arthritic deformities of the knee are classified as varus or valgus, with or without patellar involvement. Patellofemoral arthritis is common in an arthritic knee. But seldom is the major source of symptoms.
Articular surface damage is commonly classified according to severity: minimal, no radiologic narrowing is seen; mild, loss of one third of the joint space; moderate, two thirds of the joint space is narrowed; and severe, evidence of bone-on-bone contact
DIAGNOSIS Examination of the knee for arthritis can be done by moving the joint under a load. (e.g., to examine medial compartment, a varus strain is applied to the knee and for the lateral compartment a valgus load is applied as the knee is moved through a ROM).
A thorough history and examination of the arthritic knee should obtain the following information:
1. Symptom location: Isolated (medial, lateral, or patellofemoral) Diffuse 2. Type of symptoms: Swelling Giving way, instability (ligament tear or weak quadriceps) Diminished ROM Mechanical (crepitance, locking, catching, pseudolocking)
3. Timing of onset Acute Insidious 4. Duration of symptoms 5. Exacerbating factors 6. Prior intervention (e.g., NSAIDs, physical therapy, injections, or surgery) and the patient s response
Crepitus can be felt under the hand applying the varus or valgus strain and pain will be reproduced.
TREATMENT OPTIONS Physical Therapy Both manual therapy and exercise have been shown to be beneficial for those with knee OA. A significant effect on pain and physical function can be achieved with use of manual therapy in treatment of those with knee OA. Because knee OA may be partially caused by restrictions of periarticular mobility as a result of adhesion.
Manual therapy may decrease restricted mobility, allowing increased excursion of these tissues and allowing reduced pain and stiffness.
Therapeutic exercises that have been proved to be beneficial include the following: Quadriceps sets Standing terminal knee extensions Seated leg presses Partial squats (not deep) Step-ups Flexibility and ROM exercises Calf, hamstring, and quadriceps stretching Knee flexion to extension Stationary biking
Standing terminal knee extensions
Seated leg presses
Partial squats (not deep)
Step-ups
Flexibility and ROM exercises
Calf Stretch
Hamstring Stretch
Quadriceps Stretching
Knee flexion to extension
Quadriceps strengthening has been a mainstay of conservative treatment for knee OA because muscle weakness can lead to functional disability.
Strong quadriceps can considerably delay the necessity for surgery. If the patella is painful, activities such as deep squatting, kneeling, and stair climbing increases pain. So those activities should be avoided.
There might be an increased risk of OA with competitive sports participation, particularly when started early in life, although the presence of OA following this does not typically lead to an increased level of disability. Other problems may increase risk such as obesity, trauma, occupational stress, and lower extremity alignment problems.
Aerobic exercise may be beneficial because it not only increases cardiovascular endurance but also helps with weight control and reduction. Aerobic programs can also reduce pain and stiffness, improve and maintain balance, and increase walking speed.
Weight Loss: Weight loss may be an important adjunct to other therapies. Although the mechanism is not clearly understod yet, it seems empirically that people who are overweight or obese may have an increased risk for developing knee OA. Reduced body weight may help by reducing loads on weightbearing joints.
Operative Treatment Operative treatment frequently is required for disabling knee pain, particularly in patients with post-traumatic knee OA.
Total Knee Arthroplasty The guidelines for rehabilitation are general guidelines and should be tailored to individual patients.
Postoperative return of 90 degrees of knee flexion is generally considered the minimal requirement for activities of daily living with an involvement of one knee. If both knees are replaced, it is essential that one knee reach more than 105 degrees of knee bend to allow the patient to rise from a normal low toilet seat.
Continuous passive motion (CPM) may be used after surgery, but there is a certain increase in wound problems with it. If CPM is to be used, therefore, the patient must come off the machine for part of the day and work at achieving full extension.
Aggressive or prolonged CPM use in patients with the potential for wound problems (such as those with diabetes or those who are obese) is limited.
Immediately after surgery, patients frequently have a flexion contracture because of hemarthrosis and irritation of the joint. These flexion contractures generally resolve with time and appropriate rehabilitation.
GOALS OF REHABILITATION AFTER TOTAL KNEE ARTHROPLASTY Preventing of hazards of bed rest (e.g., DVT, PE, pressure ulcers) Assistance with adequate and functional ROM Strengthening thigh musculature Assisting patient in achieving functional independent activities of daily living. Achieving independent ambulation with an assistive device.
Management of Rehabilitation Problems After Total Knee Arthroplasty
Flexion Contracture (Difficulty Obtaining Full Knee Extension)
Initiate backward walking Perform passive extension with the patient lying prone with the knee off the table, with and without weight placed across the ankle.
Perform eccentric extension. The therapist passively extends the leg and then holds the leg as the patient attempts to lower it slowly. With the patient standing, flex and extend the involved knee.
Rubber bands can be used for resistance. Use electric stimulation Passive extension is also performed with a towel roll placed under the ankle and the patient pushing downward on the femur.
Delayed Knee Flexion Passive stretching into flexion by therapist Stationary bicycle If patient lacks enough motion to bicycle begin cycling backward, then forward.
Total Knee Replacement Protocol Major goals for musculoskeletal rehabilitation are to restore a person s mobility and functional capacity.
Strength should remain a focal point of rehabilitative activity, and the majority of patients benefit from strength training. Balance, mobility, coordination of movement, and gait should all be addressed also.