Tenosynovitis is often mechanically induced and can be caused by the presence of anatomical variants, after acute trauma, or by displacement. Causes can also include mechanical overload and repetitive microtrauma, as well as systemic joint diseases - primarily rheumatoid arthritis, RA - and infections.
In rheumatic systemic diseases, local inflammatory processes in the wrist and hand area can lead to destruction of bones, cartilage, capsular ligament apparatus, tendon gliding tissue, and tendons, causing pain, deformities, loss of function, and tendon ruptures [1, 2]. The pathogenesis of rheumatic hand deformity is based on the inflammation-induced proliferation of 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 early in the disease [1 – 4].
In RA, the frequently occurring involvement of tendons and tendon compartments can persist for months before intra-articular symptoms appear [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 when synovitis persists despite systemic and local medication measures. Previously, a period of 6 months after the start of basic therapy was specified. In cases of non-response to basic therapy, early hand surgical therapy after 8 weeks is now being discussed [7].
For tenosynovectomy of the extensor tendon compartments due to RA, all extensor tendon compartments are decompressed sequentially. Synovitis is usually most pronounced under and distal to the extensor retinaculum. Even though decompression of the tendons alone already has a favorable effect on the tendon tissue, the most radical synovectomy of all tendon compartments is advisable [7].
The relocation of the extensor retinaculum under the extensor tendons serves as protection against bony components of the carpus and as a gliding structure to prevent adhesions of the tendons to the joint capsule. Retinaculum plasty should, if possible, be performed partially to prevent a subcutaneous bowstring phenomenon of the extensor tendons [7].