JOINT REPLACEMENT REHABILITATION

JOINT REPLACEMENT REHABILITATION

Total joint replacement, or arthroplasty, represents a significant advance in the treatment of painful and disabling joint pathologies.

Total joint replacement can be performed on any joints of the body, including the hip, knee, ankle, foot, shoulder, elbow, wrist, and fingers. Of these procedures, hip and knee total joint replacements, are by far the most common.

Treatment of the diseased hip or knee joint does not end with surgical replacement. The ultimate goal is ensuring pain-free function of the joint to improve the patient's quality of life (QOL). Postoperative rehabilitation is of the utmost importance.

TERMINOLOGY

• THR [Total Hip Arthroplasty (THA)] - Replacement of the femoral head and the acetabular articular surface

• Hemiarthroplasty - Replacement of only the femoral head

• Bipolar hemiarthroplasty - A specific form of hemiarthroplasty in which a femoral prosthesis is used with an articulating acetabular component; the acetabular cartilage is not replaced. The principle of this procedure is to decrease the frictional wear between the femoral head prosthesis and the cartilage of the acetabulum.

• TKR [Total Knee Arthroplasty (TKA)] - Replacement of the articular surfaces of the femoral condyles, tibial plateau, and patella; the anterior cruciate ligament is excised. The posterior cruciate ligament may be saved in cruciate-retaining systems.

• Unicompartmental knee replacement [Unicompartmental Arthroplasty] - Replacement only of the medial or lateral tibiofemoral compartment of the knee

• Cemented joint replacement [Cemented Joint Arthroplasty] - A procedure in which bone cement or polymethylmethacrylate (PMMA) is used to fix the prosthesis in place in the joint

• Ingrowth, or cementless, joint replacement - A procedure that does not involve bone cement to fix the prosthesis in place; an anatomic or press fit with bone ingrowth into the surface of the prosthesis leads to a stable fixation. This procedure is based on a fracture-healing model.

• Primary joint replacement  - The first replacement surgery

• Revision - A second or succeeding surgery; it is usually performed for an unstable, loose, or painful joint replacement.

MEDICAL CARE DURING REHABILITATION

TREATMENT AND MONITORING OF MEDICAL COMORBIDITIES

During the initial evaluation of the patient, the physician must perform a thorough physical examination, not just an examination of the affected joint.

Associated medical conditions also need to be identified and addressed. These comorbidities directly impact the outcome of rehabilitation.

Communicating with the patient's primary care physician ensures that there is continuity of treatment of associated medical conditions. Medications may need to be changed or modified, depending on the patient's vital signs and laboratory profiles.

PAIN CONTROL

Adequate analgesia for the patient should be a priority during rehabilitation. It must be remembered that these patients have undergone a major joint reconstruction and may experience moderate to severe pain.

The administration of analgesics should be performed around the clock rather than just on an as needed (prn) basis. With prn dosing schedules, the analgesics are usually given too close to the time that the patients are seen for therapeutic exercises. Patients complain of pain and are not as cooperative as they would have been had they been following a regular pain medication schedule.

A long-acting narcotic analgesic provides extended pain relief in appropriate cases. Attention to side effects of these narcotic analgesics is a priority. Elderly patients are prone to develop side effects, such as mental status changes, which limit their participation in rehabilitation sessions.

These individuals are perceived as confused and uncooperative; therefore, they are thought of as poor candidates for rehabilitation. Long-acting narcotic analgesics should be tapered once this becomes appropriate and should subsequently be changed to a prn schedule.

Determination of the cause of pain is a very important aspect of pain treatment. The physician may want to take the following questions into consideration:

• Is the patient suffering from pain at the operative site or from joint pain, periarticular pain, or neuropathic or radicular pain?

• Is the pain associated with fever?

• Is the pain associated with weight bearing or range of motion (ROM)?

• Is there evidence of a vascular compromise associated with the pain?

An appropriate diagnostic work-up should be performed to identify the cause of pain. This work-up may include the following:

Ø  Complete blood cell (CBC) count, wound cultures, and erythrocyte sedimentation rate (ESR) tests are performed in cases of suggested infection.

Ø  If appropriate, electromyogram (EMG) and radiologic tests, including radiography, ultrasonography, magnetic resonance imaging (MRI), or computed tomography (CT) scanning, should be performed in cases that suggest nerve injury. Radiologic evaluations may be limited to plain films because the presence of the metallic implant limits the use of MRI and CT scanning. It should be remembered that with any surgical procedure, complications, such as infection and neurovascular injuries, can cause postoperative pain.

BOWEL AND BLADDER FUNCTIONS

• Constipation is one of the most frequent complaints during rehabilitation. This condition can be caused by decreased mobility or post-anesthesia effects; it can also be a side effect of narcotic analgesics. If untreated, constipation can lead to nausea and vomiting, bowel obstruction, or even sepsis, especially in the elderly patient. An adequate bowel program, using stool softeners and laxatives, is needed. An enema may be appropriate in some cases.

• At times, patients are admitted to the rehabilitation unit with a Foley catheter still in place. The Foley catheter should be removed if there has been no problem with bladder retention. Patients with persistent bladder dysfunction should be referred to a urologist for evaluation.

NUTRITION AND HYDRATION

Elderly patients have always been at risk for malnutrition or dehydration stemming from physical limitations or cognitive deficits. These patients need to be screened by a dietitian for appropriate nutritional intake.

Dehydration can lead to acute metabolic or renal problems that affect the patient's participation in the rehabilitation program.

PREVENTION OF THROMBOEMBOLIC COMPLICATIONS AFTER TOTAL JOINT REPLACEMENT

THROMBOEMBOLIC DISORDER

Compared with other surgical procedures, joint replacement is associated with a high risk of deep venous thrombosis (DVT) and pulmonary embolism (PE).

Without prophylaxis, the incidence of DVT after total knee replacement (TKR) is 50-84%; after total hip replacement (THR), 47-64%.

With prophylaxis that uses anticoagulation therapies, the incidence is reduced 22-57% after TKR and 6-24% after THR.

Clinical surveillance of thromboembolic disorders is not reliable. The accuracy of relying on signs and symptoms that are attributed to DVT is less than 50%.

Any suggestion of DVT warrants a radiologic evaluation, such as a Doppler ultrasound.

A venogram may be necessary. If a PE is suggested, a ventilation-perfusion (VQ) scan should be performed.

Pulmonary angiogram also may be necessary. A pulmonologist should be consulted in these cases. Although uncommon, distal DVT has been associated with PE.

What constitutes appropriate prophylaxis? Each institution has its own protocol but most use low – molecular-weight heparin or warfarin.

Low – molecular-weight heparin, such as enoxaparin, is administered at 30 mg SC bid or q12h or at 40 mg once daily, depending on the institution.

The warfarin dose is titrated to maintain an activated partial thromboplastin time/international normalized ratio (aPTT/INR) of 2.0-3.0. The duration of prophylaxis varies.

If the use of anticoagulation therapy is contraindicated, mechanical devices, including intermittent pneumatic stockings, have proven to be of benefit.

Using the same principle, newer devices that apply compression only around the foot and ankle area have been used (PlexiPulse boots). High-risk patients may need placement of an inferior vena cava (IVC) filter.

PRECAUTIONS AFTER TOTAL JOINT REPLACEMENT

PRECAUTIONS FOR PATIENTS TO PREVENT HIP DISLOCATION AFTER TOTAL HIP REPLACEMENT

Standard Precautions given to patients to prevent posterior hip dislocation include the following:

Ø  Do not cross your legs.

Ø  Put a pillow between your legs if you lie on your side.

Ø  Do not turn your leg inward.

Ø  Sit only on elevated chairs or toilet seats.

Ø  Do not bend over from the hips to reach objects or tie your shoes.

Ø  An assistive device or reacher is necessary to safely perform activities of daily living (ADL).

In some patients at risk for hip dislocation, individualized precautions are necessary, and the use of a hip abduction brace may be required.

An increase has occurred in the number of hip replacements performed through the anterior surgical approach.

Among the advantages of this procedure is the fact that it is minimally invasive, preserving the hip musculature; the posterior approach, in contrast, involves the detachment of the posterior hip rotator muscles and the mobilization of the gluteus medius muscle. With the anterior approach, the risk for hip dislocation is reduced.

The patient has almost no restriction of physical activity during the postoperative period. Less tissue injury and, subsequently, less pain occur. In addition, recovery is faster.

RESTRICTIONS ON WEIGHT BEARING AND EXERCISE

• Patients with cemented joint replacements can weight bear as tolerated (WBAT) unless the operative procedure involved a soft-tissue repair or internal fixation of bone.

• Patients with cementless, or ingrowth, joint replacements are put on partial weight bearing (PWB) or toe-touch weight bearing (TTWB) for 6 weeks to allow maximum bony ingrowth to take place.

• A knee immobilizer sometimes is worn by the patient after a total knee replacement until quadriceps strength is regained. The use of the immobilizer is typically discontinued once the patient can do straight leg raising (SLR) without difficulty.

• Ambulating with weak quadriceps muscles can lead to instability or giving way of the knee, which can be painful and may lead to unnecessary stress on the newly implanted joint.

• Quadriceps ruptures can result from high tensile forces acting on the quadriceps tendon when the patient tries to break a fall. In certain situations, careful resistive or gradual ROM exercises are initiated.

• During the surgical approach to the hip joint, a trochanteric osteotomy may be necessary, especially in revision surgery. This procedure involves detaching the hip abductor mechanism. After this mechanism is repaired, the patient should avoid abduction exercises.

• With surgical approaches to the knee, an extensive quadriceps exposure may require repair or a patellar tendon exposure may need to be fixed. ROM exercises may have to be limited and gradually increased.

CONTINUOUS PASSIVE MOTION AFTER TOTAL KNEE REPLACEMENT

The issue of the utility of employing a continuous passive motion (CPM) machine to improve ROM of the knee after total knee replacement has never been resolved.

Outcome measures focus only on the ROM that is measured postoperatively and then again at the time of discharge or at a later follow-up time. To decide whether to use a CPM machine, the physician must review the kinematics of the gait cycle.

Research has shown that the total knee flexion that is needed to ambulate on level surfaces is approximately 65-70 º. In the preswing stage, flexion of 35-40 º is needed to clear the foot, followed by an additional 30 º in the initial swing, assuming that the patient has normal hip function.

To be able to do stair climbing, approximately 83 º of knee flexion is required to clear the foot. Similar measurements have been obtained in other studies; joint reaction forces also have been measured.

A patient who lives in a 1-level home needs less knee flexion during the immediate postoperative period than does a patient who lives in a multilevel home. Another situation to consider is whether the patient lives alone.

    This individual requires maximum knee flexion to negotiate stairs independently and safely. Although there has been no agreement on

the benefits of using a CPM machine in the peri-operative period, there has been unanimity of opinion that patients achieve the same amount of knee flexion on long-term follow-up with or without the use of a CPM machine.