Synovectomy of Rheumatoid Joints

Fig. 5.1

Synovitis and pannus growing over the articular cartilage at the lateral femur condyle in a patient with rheumatoid arthritis of the knee

Surgical removal of all macroscopic detectable inflamed synovial tissue – synovectomy – is an established method of treatment for longer-lasting synovitis for rheumatoid patients complaining of joint swelling, tenderness, and pain despite regular medical therapy for 6 months. The exact timing for surgical intervention should be the result of an interdisciplinary discussion between internal and orthopedic rheumatologist.

Synovitis in osteoarthritis in contrast to rheumatic diseases is a cytokine-dependent reaction to detritus originating from cartilage breakdown. The rationale to remove synovitis by surgical means does not work in osteoarthritis because the underlying disease is the problem of cartilage breakdown which is not addressed by synovectomy. Synovectomy in osteoarthritic conditions has shown little short-lasting benefit and overall disappointing clinical outcomes and therefore is not recommended in recent guidelines.

Early synovectomy is performed in radiological Larsen stages 0-II, late synovectomy in Larsen stages III-IV (Table 5.1). It is thought that an early synovectomy may prevent further joint destruction but clinical trials of high quality to prove this are lacking. Late synovectomies have the goal to decrease pain and improve function.

Table 5.1

Larsen’s grading system for RA

Grade	Definition
0	Normal
1	Soft tissue swelling, slight joint space narrowing (<25 % of the original joint space), periarticular osteoporosis
2	Definite early abnormality, one or several small erosions
3	Medium destructive abnormality, marked erosions
4	Severe destructive abnormality, large erosions
5	Gross deformity, the bony outlines of the joint have disappeared

At present there are no comparative clinical data for a staged algorithm if synovectomy or radiosynoviorthesis should be performed first or which intervention is superior to the other. RSO may be preferred as it is less invasive needing no systemic anesthesia. RSO can be repeated and has the possibility of open surgery if being not successful. On the other hand there are hints that synovectomy closely followed by RSO may lead to better outcomes in knee synovectomy. Further controlled trials are needed.

As a result of the tremendous progress in medical treatment, the need for surgical interventions in arthritic joints declined over the last three decades in many countries. Especially the numbers of synovectomy dropped steadily also in Germany from a reported 5.6 % of rheumatoid patients in 1993 to 3.5 % in 2000 to 0.3 % in 2008 [1].

5.2 Synovectomy of the Knee

As synovectomies of the knee are the most common interventions, there are more data about results of treatment available than in other joints.

Synovectomy of the knee may be performed as an arthroscopic or open surgery. Arthroscopic synovectomy is mostly performed in early Larsen stages and demonstrated its effectivity in a multicenter trial of 93 knee joints in 81 patients with early forms of rheumatoid arthritis at a follow-up time of 33 months [2]. The Lysholm score (an established knee score relating to pain, swelling, instability, and functional outcome: 0–100 points) increased from 43.2 points preoperatively to 78.1 points. The Insall knee and functional score (an established knee score especially for use in knee joint replacement relating to pain and range of motion, 100 points, and additionally to knee function, 100 points) showed a highly significant increase of 25.7 and 25.2 points to 71.2 and 80.2 points, respectively. Among the individual variables investigated, pain, swelling, and walking distance in particular were improved. Larsen stages worsened slightly from 1.57 preoperatively to 1.95 at follow-up.

Even in advanced Larsen stages, open synovectomy of the knee demonstrated over a period of more than 10 years (10.1; range 6.4–12.7) a long-lasting improvement of function [3]. Despite reasonable functional results radiographic progression of disease was observed (Larsen stage 2.2–3.7). The need for joint replacement in nearly three-quarters of the patients could be delayed for more than 10 years.

A recent meta-analysis [4] analyzed all published synovectomy trials to find out whether open or arthroscopic surgery leads to better results. Arthroscopic and open synovectomy provided similar pain relief (Fig. 5.2a) at last follow-up for knees (p = 0.16).

Fig. 5.2

Mean results after synovectomy of the knee. (a) Percentage of patients with pain relief. (b) Percentage of patients with radiologic progression [4]

Arthroscopic synovectomy was more likely than open synovectomy to lead to recurrence of synovitis at knees (p < 0.001) and to lead to radiographic progression (Fig. 5.2b) for knees (p = 0.001). Open synovectomies were more likely to require joint replacement or arthrodesis (p = 0.01) at last follow-up, but this may be influenced by an indication bias as the number of patients with advanced rheumatoid arthritis at time of intervention was nearly double as high in open synovectomy.

In the multicenter trial with a mean follow-up of 33 months [2], patients receiving additional radiation synovectomy showed a highly significantly better result than those receiving synovectomy alone. In contrast to this finding, this positive effect does not seem to last over time as in a 14-year follow-up trial, it was found that after 5 years there was a steadily increase in worsening of joint destruction leading to joint replacement. Nearly half of the knees were converted to joint replacement after 10 years and 60.4 % after 14 years. This observation challenges the long-term benefit of the combined procedure.

5.3 Synovectomy of the Hip

There have been disappointing results in cases of synovectomy of the hip joint in adults especially in late-stage cases. Therefore, it is not recommended as a standard procedure at time although clinical trials are lacking. It seems to be more promising to perform total joint replacement in advanced stages of rheumatoid hip involvement instead.

There are data in patients with juvenile arthritis showing that even in late stages of the disease (Larsen III and higher) open synovectomy combined with soft tissue procedures leads to an improvement in function [6]. Merle d’Aubigné hip score (an established hip score relating to pain, range of motion, and walking ability: 0–18 points) significantly improved from 9.5 ± 2.5 points at baseline to 16.3 ± 1.0 points at the time of follow-up (p < 0.001). The individual scores for pain, mobility, and walking ability were significantly increased as well (all p < 0.001). Eighty-five percent of the 56 hips were observed to have a very great or great improvement in function. Osteonecrosis of the femoral head was not observed. Five hips required total hip arthroplasty during the follow-up period. Thus, the survival rate for the hips was 94 % at a mean of 4 years following the synovectomy.

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