Arthroscopic Synovectomy of the Knee

History

A complete history is important in the evaluation of patients with synovial disorders. The presence of other affected joints, chronicity of symptoms, exacerbating factors, and the amount of disability experienced by the patient on a daily basis are important pieces of information. Patients with rheumatoid arthritis may have more systemic complaints, including morning stiffness and other affected joints, particularly the small joints of the hands and feet. PVNS is typically a monoarticular process that affects adults in the third or fourth decade of life. Symptoms are mechanical in nature and may be similar to those seen in patients with meniscal tears. Clinically patients have the insidious onset of localized warmth, swelling, and stiffness with occasional locking and a palpable mass. Plica syndrome is a finding in patients with anteromedial knee pain. Patients experience tightness, snapping, giving way, and pain with repetitive activities. Clinically it is difficult to distinguish plica syndrome from other causes of knee pain such as meniscal tears, patellar tendinitis, or patellofemoral pain syndrome.

Physical Examination

Other joints may be affected in patients with rheumatic or autoimmune disorders, and these joints should be evaluated. Patients with rheumatoid arthritis often have a flexion contracture and quadriceps atrophy in the knee region. The skin should be examined, as well as previous incisions and subcutaneous nodules. Knee examination includes overall alignment, range of motion (ROM), the presence of an effusion, warmth, tenderness, crepitus, strength, meniscal integrity, and stability. Collateral ligament instability or bony malalignment suggests more severe articular loss, and patients with these conditions are poor candidates for a synovectomy.

The physical examination for PVNS is often nonspecific. An effusion is associated with diffuse involvement. Palpation of the joint may show warmth and tenderness. Aspiration of the joint fluid may show a dark-brown fluid that is a result of recurrent bleeding into the joint. Cytologic studies of the aspirate may show hemosiderin pigment and multinucleated foreign body giant cells, but often the findings of these studies are normal. Ligamentous instability is uncommon in persons with PVNS.

Plica syndrome begins insidiously. Tenderness over the medial parapatellar region is common. A plica may sometimes be directly palpated and rolled under the finger, recreating the patient's symptoms. If the medial border of the patella is palpated while pushing the patella medially with one hand and the other hand produces a valgus stress with external rotation of the tibia, pain may be elicited, suggesting plica syndrome. An effusion is not typically present in persons with plica syndrome.

Imaging

Patients with rheumatoid arthritis may have periarticular erosions and osteopenia. Cervical spine flexion and extension views should be obtained in preoperative patients to rule out cervical instability. Radiographs in patients with PVNS can show erosive, cystic, and sclerotic lesions of the articular surface. If enough synovium that contains hemosiderin is present, soft tissue masses may be seen, but often the findings of the films are normal with well-maintained joint spaces. Magnetic resonance imaging is considered to be the most diagnostic study for PVNS. It may show nodular intra-articular masses of low signal intensity on T1- and T2-weighted images and also allows for the evaluation of the location and extent of disease.

Decision-Making Principles

A full rheumatologic workup should be completed for patients with systemic diseases, and appropriate laboratory tests should be up to date. Patients with hemophilia require a consultation with a hematologist. If surgical treatment is to be pursued, it is essential to have a well-thought-out plan for perioperative management of clotting factors.

In disorders associated with a localized lesion, such as a localized PVNS ( Figs. 93.1 and 93.2 ) or plica, arthroscopic intervention can remove the pathology in its entirety. Persons with diffuse conditions such as rheumatoid arthritis ( Figs. 93.3 through 93.6 ) or hemophilia can undergo surgery to decrease the severity of disease symptoms once conservative measures have been exhausted.

Treatment Options

Treatment options vary based on etiology. Recently medical management of rheumatoid arthritis has improved significantly. The goals of medical treatment include reducing the number of painful and swollen joints, suppressing the acute phase response, decreasing the rheumatoid factor titer, and slowing radiographic progression of the disease. Medical management should consist of a combination of disease-modifying antirheumatic drugs, nonsteroidal antiinflammatory drugs, an appropriate physical therapy regimen, activity modification, and intra-articular steroid injections. A patient with rheumatoid arthritis and minimal degenerative changes on radiographs would be a candidate for arthroscopic synovectomy after the failure of approximately 6 months of medical management. Significant joint space narrowing or mechanical malalignment is a relative contraindication to synovectomy for inflammatory synovial knee disorders, and a total knee arthroplasty is recommended.

Hemophilic synovitis can also be associated with significant joint destruction and has shown favorable improvement in symptoms with synovectomy. Radiosynovectomy is indicated as the first procedure in persons with hemophilic synovitis, with satisfactory results in 80% of patients. No more than three radiosynovectomies can be performed per year. If the three radiosynovectomy procedures fail to relieve symptoms, an arthroscopic synovectomy is indicated. Although joint deterioration is not preventable, a synovectomy can reduce recurrent hemarthrosis and maintain ROM. A hemophilic synovectomy requires an inpatient stay for coordinated management of clotting factors with the patient's hematologist.

In PVNS, arthroscopic synovectomy is the treatment of choice for localized disease, but open synovectomy may be required for diffuse-type PVNS and recurrence of local tumors. Adjuvant therapies including intra-articular radiotherapy or moderate-dose external beam radiotherapy further reduce likelihood of recurrence with advanced forms and recurrent disease.

Authors' Preferred Technique

Arthroscopic synovectomy requires the use of multiple portals to access all spaces in the knee joint; therefore detailed preoperative planning and patient setup is essential for a successful operation. General anesthesia is recommended, and the use of a Foley catheter should be considered. An epidural can be used if required for medical reasons and may also help with postoperative pain relief.