Tenosynovitides are often mechanically induced and can be caused by the presence of anatomical variants, after acute trauma or by displacement. Causative factors can also include mechanical overload and repetitive microtraumas as well as systemic joint diseases - foremost rheumatoid arthritis, RA - and infections.
In rheumatic systemic diseases, local inflammatory processes in the area of the wrist and hand can lead to destructions of bones, cartilage, capsuloligamentous apparatus, tendon gliding tissue and tendons, which can cause pain, malpositions, loss of function and tendon ruptures [1, 2]. The pathogenesis of the rheumatic hand deformity is based on the inflammation-induced proliferation of the synovial tissue, which can affect the large and small joints of the hand, extensor and flexor tendon compartments. The existence of various synovial spaces in numerous joints, which occasionally communicate with each other, and the many different types of tendon gliding tissues explain the multitude of clinical problems that can occur already at an early stage of the disease [1 – 4].
In RA, the frequently occurring involvement of the tendons and tendon compartments can persist for months before intra-articular symptoms occur [5]. Typical locations of inflammation are the dorsal and palmar wrist area as well as the flexor tendon sheaths of the fingers [2, 4, 6].
Tenosynovectomy is indicated if the synovitis persists despite medication-systemic and local measures. For this, a period of 6 months after the start of basic therapy was previously specified. In case of non-response to basic therapy, an early hand surgical therapy after 8 weeks is now being discussed [7].
For the tenosynovectomy of the extensor tendon compartments due to RA, it applies that all extensor tendon compartments are decompressed one after the other. Usually, the synovitis is most pronounced under and distal to the extensor retinaculum. Even if the decompression of the tendons alone has a favorable influence on the tendon tissue, the most radical synovectomy of all tendon compartments possible is advisable [7].
The displacement of the extensor retinaculum under the extensor tendons serves as protection against bony parts of the carpus as well as a gliding structure to prevent adhesions of the tendons to the joint capsule. The retinaculum plasty should be performed partially if possible to prevent a subcutaneous bowstring phenomenon of the extensor tendons [7].