Total Knee Arthroplasty in Rheumatoid Arthritis

Ipsilateral Hip Involvement

Ipsilateral hip involvement is more frequent in rheumatoid arthritis than in osteoarthritis. The hip should always be thoroughly evaluated before TKA and, with few exceptions, the hip should be replaced before the knee surgery. I can think of at least six reasons for this. The first reason is that it is best to first resolve any knee pain that is referred from the hip. At times, the knee arthroplasty can even be delayed because of the pain relief gained by replacing the hip. In cases in which it is critical to resolve the source of the knee pain, the hip joint should be injected with bupivacaine under fluoroscopic control ( Fig. 9.1 ). The patient can then report on the extent of pain relief gained. If the pain relief is considerable, both patient and surgeon are more comfortable with the decision to proceed with the hip first.

The second reason is especially important in the juvenile patient with rheumatoid arthritis. Because the hip surgery is relatively easy and painless for the patient (compared with the knee surgery), the surgeon gains the patient’s confidence. In contrast, if the knee is operated on first, the pain and difficult rehabilitation that the patient endures without a significant gain in function discourages the patient who still has pain and lack of function.

A third important reason for replacing the hip first is the fact that a person can exercise a hip above a painful arthritic knee, whereas it is difficult to exercise a knee below a painful, stiff, arthritic hip. I believe that a stationary bicycle is extremely helpful during rehabilitation of knee arthroplasty, but it is not important to the rehabilitation of a hip replacement. The use of a bicycle is not possible when the hip above is painful and stiff.

The fourth reason is to resolve the tension of muscles that cross both the hip and knee joint, especially the hamstrings. If, for example, both the hip and knee have flexion contractures and the knee is operated on first, resolving that contracture, a subsequent hip replacement that lengthens the hip can retighten the hamstring muscle.

The fifth reason for replacing the hip first is also related to preoperative knee contractures. At the time of hip arthroplasty, a contracted knee can be manipulated and casted to improve passive extension before the knee replacement. If epidural anesthesia is used, it can be maintained for several days and serial casts can be applied (see Chapter 7 , Fig. 7.2 ).

Finally, the sixth reason is because it makes sense to avoid twisting and torqueing a well-balanced TKA while dislocating and exposing a stiff hip for replacement.

Anticoagulation Needs

In my experience, deep vein thrombosis (DVT) and pulmonary emboli occur less frequently in patients with rheumatoid arthritis than in those with osteoarthritis. This may be partially because most patients with rheumatoid arthritis require the chronic use of antiinflammatory medications, which have a mild anticoagulation effect. It might also be intrinsically related to their disease process. The reason is unclear, but it makes their anticoagulation needs different from those of patients with osteoarthritis.

Because anticoagulation medications and protocols will continue to evolve through the years for both rheumatoid and osteoarthritic patients, they will not be discussed here.

Flexion Contracture

The treatment principles of treating flexion contractures are discussed in Chapter 7 . Because flexion contractures are more prevalent in rheumatoid arthritis than in osteoarthritis, I will readdress them in this chapter. The contracture in a rheumatoid patient is more likely to be caused by inflammation in the soft tissues, whereas the flexion contracture of osteoarthritis is usually associated with a bony block (see Chapter 7 ). After studying the outcomes of a large number of patients with severe contractures, I have developed the following treatment guidelines for patients with rheumatoid arthritis.

For flexion contractures less than 15 degrees under anesthesia, I performed a normal distal femoral resection and posterior capsular stripping as needed. If the flexion contracture was between 15 and 45 degrees, I increased the distal femoral resection by 2 mm for every additional 15 degrees of correction that was necessary. I limited this to a total of 13 mm to avoid compromise of the femoral origins of the collateral ligaments.

Between 45 and 60 degrees of flexion contracture, I considered preoperative manipulation and casting and always used a posterior cruciate ligament (PCL)-substituting technique. For flexion contractures greater than 60 degrees, I also considered preoperative manipulation and casting (see Fig. 7.2 ) and a constrained articulation such as a Total Condylar III (DePuy, Inc., Warsaw, Indiana) to resolve the flexion gap laxity that can result from significant elevation of the femoral joint line.

For patients with inflammatory arthritis, I followed the “rule of one-third.” This states that intraoperative correction need only be to within one-third of the preoperative contracture under anesthesia. The residual one-third usually resolves with physical therapy, resolution of the inflammatory disease, and occasionally the help of manipulation and casting. The most dramatic example I have seen was a patient with bilateral 110-degree flexion contractures. One knee was ankylosed at this degree of flexion, and the other knee was fused. The techniques described previously were used, including the Total Condylar III prosthesis. At the end of surgery, the flexion contracture was corrected to 40 degrees. After three serial casts applied under epidural anesthesia over 3 days, the patient’s flexion contracture was corrected to zero.

Several additional points regarding flexion contractures should be emphasized. If the patient has bilateral, severe flexion contractures, both should be corrected simultaneously to avoid the risk for regression of the correction on the first side until the second side is corrected.

When the capsule is closed after correction of a severe flexion contracture, the medial capsule should be advanced distally on the lateral capsule to avoid an initial extensor lag (see Fig. 6.5 ).

The amount of posterior slope applied when dealing with a severe flexion contracture should be zero degrees. Every degree of slope built into the tibia creates a degree of flexion contracture or, put another way, prevents its correction.

Finally, ancillary preventive measures should be taken after surgery, such as allowing the patient to have a roll under the ankle but never under the knee. A knee immobilizer at night will prevent the patient sleeping with flexed knees and redeveloping a contracture. A dynamic extension splint can be helpful to both correct and maintain extension in refractory cases.

Rheumatoid Cysts

Although small juxtaarticular cysts are not uncommon in osteoarthritis, they are more frequently seen in rheumatoid arthritis, and occasionally very large cysts are present on either the femoral or tibial side of the joint. All cysts should always be curetted free of soft tissue and grafted with cancellous bone to seal the cyst wall from the cement interface. In my experience, failure to do this in patients with rheumatoid arthritis leads to the possibility of progressive demarcation at the cement–cyst interface, leading to component loosening ( Fig. 9.2 ). Examination of the tissue at the loosening interface shows histologic features consistent with those of recurrent rheumatoid synovium.

Larger central defects can be treated with an impaction grafting technique (see Chapter 10 ). In this technique, morselized bone graft is packed densely around a long trial stem. When the trial stem is removed, the graft should be so densely packed as to provide structural integrity (see Fig. 10.10 ). Depending on the distal bone quality in the tibia, the stem of the real component can either be press fit or cemented. If the cemented technique is chosen, the canal is plugged with a cement restrictor before application of the bone graft.