Abstract
Synovial biopsies of the knee joint are commonly performed arthroscopically with the patient under full or regional anesthesia. To overcome the effort, costs, and potential risks of surgery, we developed an office-based technique for retrograde synovial biopsy using a designated novel biopsy forceps. Using this technique, no arthroscopic or radiologic control is needed to perform rapid synovial biopsies of the knee joint. Concomitant aspiration of synovial fluid can be performed. A technical description of the procedure is given.
Synovial biopsies are commonly required for the diagnosis of rheumatic, metabolic, or septic causes of arthritis. Several disorders of the joint can only be detected by histologic analysis of synovial tissue (e.g., sarcoidosis, amyloidosis, chondromatosis, or hemochromatosis).1 Histologic evaluation is the method of choice in the diagnosis of undifferentiated rheumatic diseases and remains the gold standard for the assessment for the inflammation grade (e.g., in rheumatoid arthritis).2 In septic arthritis and periprosthetic joint infections, synovial biopsy has a higher sensitivity and specificity compared with synovial fluid aspiration alone.3 Furthermore, foreign-body inflammation induced by abrasion of metal, polyethylene, or ceramic implants can be detected and classified by histologic examination of the biopsy specimen.4
Most synovial biopsies are performed in an arthroscopically assisted manner, requiring the infrastructure of an operating theater. Partial or total anesthesia is needed. A cost-effective, office-based, simple technique for synovial biopsies with patients under local anesthesia without the need for radiologic imaging (fluoroscopy, ultrasonography) would be favorable. We describe a procedure using a novel device for retrograde synovial biopsies and simultaneous fluid aspiration (or injection). Arthroscopic or radiologic control for instrument placement is not needed.
Surgical Technique
The detailed technical aspects of our novel approach for synovial biopsies of the knee joint are discussed in this report, and for demonstration purposes, the intervention was performed during a diagnostic arthroscopy of the knee joint (Video 1). The retrograde forceps (Retroforceps; Karl Storz, Tuttlingen, Germany) (Fig 1A) used for this technique consists of a trocar with a semi-blunt round tip and a modified reverse flap (Fig 1B). The flap has teeth on the “retrograde” side, facing away from the tip. Under the flap, there is a “biopsy chamber” with sharp sides. Inside the trocar, there is a fluid channel leading from the distal entry on the flap to the proximal suction portal.
Fig 1.
Retrograde biopsy forceps. (A) The forceps consist of a grip, a shaft with a suction port, and a blunt tip with a jaw. (B) The blunt tip (asterisk) contains a reverse jaw (plus sign) with the teeth facing the synovial membrane. A small bore (arrow) is used for aspiration.
The patient is positioned supine with the knee in an extended position. The patient must be able to relax the quadriceps muscle. The approach for the biopsy is identical to the lateral approach for aspiration at the suprapatellar recess. A local anesthetic (lidocaine with epinephrine [Rapidocain; Sintetica SA, Mendrisio, Switzerland]) is injected subcutaneously into the insertion site and extended deeper down to the capsule. If no septic arthritis is suspected, a local anesthetic can also be injected intra-articularly. A small 2-mm incision is made at the insertion point. The forceps is forwarded toward the suprapatellar pouch. Resistance is first felt while crossing the retinaculum. A syringe is attached to the suction portal of the forceps (Fig 1A). Under continuous aspiration, the forceps is advanced until it passes the resistance of the capsule and synovial fluid can be aspirated (Fig 2A). This indicates the intra-articular position of the flap (Fig 2B). The synovial fluid can be collected for further analysis at this point. The handles of the forceps are now opened, which opens the reverse flap at the distal end of the trocar (Fig 2C). The forceps is pulled back with the open flap facing the synovial membrane (Fig 2D). Resistance is felt, indicating correct positioning of the flap at the capsule. The handles of the forceps are then closed, which shuts the jaw acquiring the tissue sample (Fig 2E). The closed forceps is retrieved from the joint. The jaw is reopened, and the tissue sample can be removed with tweezers. By use of the same skin incision, several samples can be taken in a short interval. After the final biopsy sample is taken, the skin incision is covered with a sterile wound dressing.
Fig 2.
Course of synovial biopsy. A small skin incision is performed at the insertion site. The forceps is forwarded until the resistance of the capsule is felt. (A) The blunt tip of the forceps penetrates the capsule and (B) is inserted into the suprapatellar pouch while under continuous aspiration. (C) The jaw is opened and now faces the synovial membrane. (D) The forceps is pulled back until the open jaw is fixed on the synovial membrane. (E) Closing the jaw acquires the synovial biopsy specimen.
Discussion
A minimally invasive, economically efficient, rapid procedure for synovial biopsies is necessary to improve patient care. Techniques using an anterograde forceps or the Parker-Pearson needle5 have been described. However, those procedures face several limitations. For the anterograde forceps, an incision opening the capsule and subsequent ultrasonographic surveillance are required. Alternatively, needle arthroscopy is an office-based technique and can be performed to survey the joint and guide antegrade biopsies, but it requires expensive arthroscopic equipment.6 With the Parker-Pearson needle, synovial biopsy is performed without arthroscopic or radiologic control.5 However, because of imprecise positioning at the synovial layer and small tissue samples, multiple biopsy attempts are often required.
The presented technique in this report is a feasible approach for multiple synovial biopsies of the knee joint. It can be performed rapidly by a single examiner without additional arthroscopic or radiologic control. The aspiration channel indicates the correct intra-articular position of the forceps and can be used for simultaneous aspiration or injection. We think that this novel method has several advantages over the commonly used techniques. The technical pearls and pitfalls are given in Table 1.
Table 1.
Pearls and Pitfalls of Retrieving Retrograde Synovial Biopsy Specimens From Knee Joint
| Pearls | Pitfalls |
|---|---|
| When inserting the forceps, the surgeon continuously applies suction with a syringe at the suction portal of the forceps. | The synovial layer is well innervated. Patients may have intolerable pain. Local anesthetics can be reapplied along the biopsy tunnel, if necessary. |
| The fluid sucked out is used for analysis. | The surgeon can use a needle to retrieve the biopsy material from the jaw if it becomes stuck. |
| By pulling back the open forceps, the surgeon will feel the resistance of the capsule at the jaw. He or she should close the handle while applying a steady amount of pull. By doing so, the chance of successfully retrieving a biopsy sample is very high. | |
| Several biopsy specimens can be acquired over the same skin incision. |
From a logistic point of view, the procedure requires a minimal amount of preparation and technical equipment. Arthroscopically assisted biopsies faces the risk of infection or other perioperative complications.7 In our opinion the risk of infection with the described method is minimal and comparable to that of knee punctures, provided that the procedure is performed following the rules of an aseptic joint puncture. The limitation of this biopsy technique is the lack of localization of a specific area of the synovial membrane to be biopsied. In case of localized synovial pathology, lesions must be detected by ultrasonography or magnetic resonance imaging before the biopsy. Often, however, such as in cases of septic arthritis or deposition disorders, synovitis is ubiquitous in the knee joint and no specific lesion needs to be targeted. If one follows the steps of the described biopsy technique, there is a high chance of retrieving a biopsy sample. In cases in which a sample cannot be retrieved, an arthroscopic approach is recommended. The exact success rate has to be further evaluated in a clinical trial.
In conclusion, the use of a retrograde biopsy forceps is a feasible, economical, and safe office-based procedure to acquire multiple synovial biopsy specimens from the knee joint.
Footnotes
The authors report the following potential conflict of interest or source of funding: T.H. is patent holder of the Retroforceps and receives license fees from Karl Storz GmbH & Co KG. T.H. receives royalties from Karl Storz GmbH & Co KG.
Supplementary Data
Biopsy technique. All steps of this procedure can be performed without arthroscopic assistance. However, to demonstrate the key steps and technical aspects of the biopsy, an arthroscopic view of the procedure is provided. The key steps are as follows: skin incision, penetrating the joint capsule with the forceps, opening the forceps, pulling the open jaw against the synovial membrane, closing the jaw, and retrieving the biopsy sample from the jaw.
References
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Associated Data
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Supplementary Materials
Biopsy technique. All steps of this procedure can be performed without arthroscopic assistance. However, to demonstrate the key steps and technical aspects of the biopsy, an arthroscopic view of the procedure is provided. The key steps are as follows: skin incision, penetrating the joint capsule with the forceps, opening the forceps, pulling the open jaw against the synovial membrane, closing the jaw, and retrieving the biopsy sample from the jaw.