The purpose of this study is to propose a modified arthroscopic technique for differential diagnosis and repair in isolated peripheral TFCC tear with proximal component involvement. Based on previous cadaver study in dynamic change of TFCC during rotation, the proximal component of TFCC is recognized as the true radioulnar ligament while the distal component functions like hammock suspension on the ulnar carpus . Atzei et al updates the concept in functional anatomy and proposed a treatment-oriented classification system with class II and class III lesions indicating proximal component involvement . The hook test and trampoline test are commonly performed to discriminate type II versus type III lesions . While positive hook test is a consistent indicator for fovea avulsion of the proximal component that could be confirmed through DRUJ arthroscopy, the trampoline test is an indirect sign for distal component tear by checking the TFCC compliance through compressive probing  instead of direct visualization in the integrity of the distal component. In our patients, trampoline test is all positive whereas only 4 exhibit complete tear in the distal component and is defined as Atzei class II lesion on arthroscopic viewing from 6R portal. In Atzei class II lesion, complete tear of both distal and proximal components allows direct visualization of ulnar head on inspecting TFCC periphery from 6R portal. We empirically call it positive visualization test. The other 8 patients, whose distal component is only in partial-thickness tear, are defined as Atzei class III lesion. Since all patients present fovea tear diagnosed with both positive hook test and DRUJ arthroscopy, it might be reasonable to lose a normal resilience response on probing for trampoline test. However, meticulous examination of the distal component from 6R portal is more straightforward to facilitate clear subtyping and allow proper surgical decision. Not only the thickness and size of the distal component tear was directly surveyed but also the whole procedure in passing TFCC FasT-Fix needle device could be meticulously monitored from 6R portal.
Both capsular and fovea repairs have been extensively adopted for surgical management of peripheral TFCC tear. Biomechanically, fovea repair is superior to capsule repair in terms of stiffness and maximal displacement of distal radioulnar joint (DRUJ) . However, systematic reviews reveal comparable clinical outcomes among different surgical techniques since there is a lack of comparison studies regarding the area of TFCC injury and DRUJ instability . In the index surgery, we implement an all-arthroscopic technique to re-approximate proximal component tear using a pre-tied suture device. There are two critical steps we believe worthy of reminding. Firstly, we use 6R portal to confirm an Atzei class II lesion through the “visualization” window in the peripheral tear, which in turn serves as a guide for FasT-fix device needle passing through the proximal component and ahead to ulnar joint capsule. Secondly, the pre-tied polyester suture loop is closed gradually by pulling the remaining limb to push down the TFCC periphery approaching ulnar fovea while keeping the retention ethibond suture in proper tension, forearm in neutral rotation and DRUJ in reduction position. Similar to the currently available repair techniques, there is no direct evidence to document the healing status of proximal component. Nor do we have intention to repair the TFCC back to the original footprint or any isometric point. Instead, we may consider the index surgery to work like an internal bracing. The internal bracing technique has been currently adapted in treating ligament injury of elbow and acromioclavicular joints [17, 18]. By internal bracing of the torn ligaments, a suspension device was applied to stabilize the joint and facilitate tissue healing .
According to Atzei’s treatment algorithm , class II and III lesions are fovea-repaired through a DRUJ approach that is technically demanding and needs bony procedures with suture anchor or osseous tunnel. The all-arthroscopic technique using a pre-tied suture device in peripheral TFCC tear was first published by Yao et al in 2007 . Long-term report at a mean 7-year follow-up in Palmer IB lesion without gross DRUJ instability exhibits promising outcome . We adapt this pre-tied suture device for use in the treatment of peripheral TFCC tear with proximal component involvement. With the arthroscope in the 6R portal, Palmer IB lesion can be clearly subcategorized. Under arthroscopic supervision, this pre-tied FasT-Fix device is introduced from 3-4 portal and advanced in the direction to re-approximate radial-displaced TFCC back to ulnar side. By pulling the retention suture in the 6U portal, the TFCC is held stable and kept in tension to facilitate accurate and sufficient purchase of the TFCC edge by the device needle. There exist several anatomical concerns regarding the safety of device needle application and PEEK block trajectory. Based on a cadaveric study for the FasT-Fix device , there is sufficient safe zone between the neurovascular structures and ulnar joint capsule where the needle tip reaches and PEEK blocks seat. Neither is any tendon injured. Biomechanical investigation shows a consistent failure mode with the suture cutting through the TFCC tissue. For prevention of cut-through complication, we recommend the use of a smooth grasp forceps to check TFCC resilience and reparability in advance and then traction suture to facilitate needle passing. In our study, preliminary outcome for treatment of Atzei class II and III lesions is promising by an all-arthroscopic FasT-Fix suture repair, which is technically simpler and can serve as a feasible alternative to suture anchor or transosseous repair. The index surgery not only can be performed solely by skipping bony procedures, but also may serve as an adjunct whenever the proximal component or fovea condition is not allowed to achieve an optimal repair.
There are several drawbacks in our study. First of all, we do not explore the fovea area. Nor is postoperative image available to document the healing of TFCC periphery. In addition, there is lack of objective measurement to avoid over-tension of TFCC during tightening the pre-tied suture loop, which could be the cause of restricted motion in the early postoperative period. Finally, only a small sample size is recruited with the limitation of retrospective review.