Carpal tunnel syndrome (CTS) is a common health issue and can be treated with a surgical carpal tunnel release (CTR) providing mainly lasting clinical relieve. However, in some patients, symptoms recur after a variable period. Redo surgery can be considered and different techniques have been propagated. This systematic review aims to investigate whether a hypothenar fat pad flap (HFF) technique provides better clinical outcomes than a second open CTR as revision surgery in these cases.

Nine out of 764 articles, included after a systematic search in four databases (PubMed, Embase, Web of Science and Scopus), met our in- and exclusion criteria. We reported following outcomes: Tinel sign, pain score, sensibility, grip- and pinch strength, (q)DASH (Disabilities of the Arm, Shoulder and Hand) score, BCTQ (Boston Carpal Tunnel Questionnaire) and/or satisfaction.

Both open CTR as HFF are likely to improve post-surgical pain and sensibility, moreover patients score better on the (q)DASH and BCTQ after the intervention. A HFF provides a significant post-surgical amelioration on both grip- and pinch strength tests and shows a clear trend towards decreased post-interventional present Tinel sign. However, for these outcomes, no data considering open CTR was available.

When interpreting the results, it is important to keep in mind the limitations of this resume. Most importantly, there were no directly comparative studies available for the selected outcomes. Meaning data from different studies reporting outcomes after either HFF or CTR were compared. Furthermore, the included studies have all quite small populations and some of them did not even do statistical analysis on their data. Although we have been very strict in selecting only patients with recurrent symptoms, there is a wide variety of definitions used to describe recurrence.

In our knowledge, this is the first systematic review with a single focus on these two procedures in a well-defined population with recurrent carpal tunnel symptoms reporting this extensive amount of outcomes. As reported outcome studies on revision carpal tunnel surgery are very heterogeneous and data are difficult to compare, no superiority of either one technique can be concluded.

We believe this review is important to highlight the lack of comparative studies in this orthopedic area and may serve as a matrix for a qualitative (randomised) controlled trial to further investigate superiority of one of both revision techniques.