Use of ultrasound-assisted arthroscopy in rheumatology: an experience in 11 patients with different rheumatic diseases

Abstract

The ‘real time' capability of ultrasound (US) allows dynamic assessment of joint and tendon movements, which can often aid in the detection of structural abnormalities. The simultaneous use of arthroscopy (AS) and US is therefore a logical progression. Here the results of a series of 11 patients with different rheumatic diseases in whom a combined use of US and AS was adopted are reported.

Keywords::

• arthroscopic synovectomy
• arthroscopy
• rheumatic diseases
• ultrasonography

Imaging procedures have changed considerably over the last 25 years and new methods for the diagnosis and treatment of rheumatic diseases such as ultrasonography and non-radiological examinations, such as arthroscopy (AS), seem to be the main reason for this change. Both AS and ultrasound (US) are established techniques, already available in many centers of rheumatology [1-5]. Arthroscopic synovectomy has many advantages over open synovectomy, including minimal invasive surgery, short hospital stay, diminution of postoperative joint stiffness and improved complete synovectomy [1-4]. Similarly, US is a simple, safe, inexpensive, noninvasive method which is accessible in most hospitals. The ‘real time' capability of US allows dynamic assessment of joint and tendon movements, which can often aid in the detection of structural abnormalities [5-7]. The simultaneous use of AS and US is, therefore, a logical progression, keeping also in mind that the images produced by each technique are comparable.

It has been previously reported that the combination of these two methods in the operating room provides a number of important advantages. It allows the ultrasonographer to immediately clarify any queries arising from the US images and the arthroscopist to visualize the deeper layers of the synovial membrane making double-guided targeted biopsies possible [8]. In order to further explore the combined use of US and AS, we present here the results of a small series of 11 patients (11 knees) with different rheumatic diseases (four rheumatoid arthritis, two psoriatic arthritis, two chondrocalcinosis, one undifferentiated seronegative arthritis and two pigmented villonodular synovitis [PVNS]) who were to undergo diagnostic or therapeutic AS (Table 1). Therapeutic synovectomy was performed in all patients, and in all patients synovitis was detected both by US and AS. US identified thickened synovial membrane in all compartments; in particular, villous protrusions were confirmed at arthroscopic visualization, with good correspondence between the two techniques (Figure 1A and B). US allowed a precise definition of the thickness and mapping of the synovial proliferation, making synovectomy more effective and saving the capsular wall (Figure 2A and B). Interestingly, in one patient, there was a septum separating the joint space; US easily identified the septum and recognized further areas of synovial proliferation. The motorized shaver perforated the septum to reach and remove synovial tissue (ST), thus avoiding the need for additional access. US-guided arthroscopy allowed good visualization of the surface and underlying structure of the synovial membrane (morphology, color and vascularization). Importantly, we also successfully performed arthroscopic synovectomy of a Baker's cyst under US guidance in one patient. The procedure was technically complex due to probe positioning and maintenance of sterile conditions–the knee was bent and the ultrasonographer had to work bent over as the patient was supine. Overall, the procedure was well tolerated and major side effects were not observed.

Table 1. Baseline characteristics of evaluated patients.

Treated knees	11 (7 left knee and 4 right knee)
Patients final diagnosis	4 Rheumatoid arthritis 2 Psoriatic arthritis 2 Chondrocalcinosis 1 Undifferentiated seronegative arthritis 2 PVNS
Males	7
Mean age of patients at time of intervention, years	47.0 ± 11.8
Mean diseases duration, years	5.7 ± 3.4
Already knew diagnosis	10
Unknown diagnosis	1 unknown synovitis that revealed to be a PVNS

Figure 1. (A) Arthroscopic image: villous proliferation of the synovial membrane of the suprapatellar pouch of a patient affected by psoriatic arthritis. (B) The same image captured with an US device during the same examination.

Figure 2. (A) Arthroscopic image of biopsy grab biopsying the synovial villum at the same location as Figure 1. (B) The same image captured with an US device during the same examination.

Minor transient side effects, such as swelling (lasting about 10 days) of the knee, were observed in two patients.

We must point out that this case series was conducted in a small number of patients, affected from different conditions; moreover, only one joint was studied (the knee). Despite these limitations, outcomes from this case series suggest that US and AS provide different information on the structures of the joint space and are complementary for the rheumatologist and confirm earlier observation in three patients [8]. The combination of the two techniques can help the ultrasonographer to give immediate answers to doubts aroused by US images, and the contemporary observation of the joint cavity with AS may also improve the performance of AS, resulting in a more complete, effective and rapid synovectomy. They are also in agreement with results of a large-scale study reported by Karim et al. which showed that with the use of AS as the gold standard, US had a higher sensitivity (98 vs 85%), specificity (88 vs 25%), accuracy (97 vs 77%), positive predictive value (98 vs 88%) and negative predictive value (88 vs 20%) compared with clinical examination [9]. The authors concluded that US is a valid and reproducible technique for detecting synovitis in the knee and is more accurate than clinical examination.

Expert opinion

The results described above may lend some support to the hypothesis that the simultaneous use of both US and AS may be valuable as a tool in studies investigating pain, diagnosis and treatment response in knee arthritis. In particular, it might allow a better evaluation of the synovial inflammation, thus guiding US and making the synovial resection more selective and radical with improved clinical outcomes. This benefit cannot be achieved without the use of US and can be relevant first because inflammation is focally distributed in the joint and second the degree of clinical improvement/postoperative prognosis of synovectomy in rheumatoid arthritis patients appears to depend on the histological composition of the ST and the extent of ST removal. In addition, US allows the estimation of synovial thickness and identification of the presence of septum (as also shown in one of the patients presented in our series), thus limiting the risk of capsule perforation. Of note, an US scan performed before AS does not allow a precise mapping of synovial membrane, since the shape of synovial membrane may change after AS access. The simultaneous use of US and AS also reduces the number of AS accesses, thus making synovial resection safer and quicker.

The simultaneous use of US and AS is not, of course, without its limitations. Like any measurement tool, US is highly dependent on technical equipment and the skills and expertise of the ultrasonographer, who should be specifically trained. Combining US and AS requires highly equipped centers and operation rooms and local factors are important in reproducibility and the usefulness of technique.

An important limitation is the loss of the power Doppler signal that indicates the areas with increased blood perfusion, because of the tourniquet use, in addition to the fact that internal knee joint is quite difficult to approach mainly from the anterior view, since there are artifacts caused by the presence of patella. On the other hand, from the posterior view, linear transducers can provide information only on the structures of the popliteal fossa and the remaining lateral and medial imaging windows provide only partial information on the extent of synovial involvement. Last–but not least–both US and AS are expensive methods, and the cost:benefit ratio of their simultaneous application should be taken into account.

Despite these limitations, we believe that this method–if confirmed in targeted studies on a larger sample size–might be of assistance in training new ultrasonographers and possibly encourage more rheumatologists to explore the arthroscopic possibilities.

Declaration of interest

The authors state no conflict of interest and have received no payment in preparation of this manuscript.