Several potential pain generators have been associated with ulnar impaction syndrome. Currently, wrist arthroscopy for ulnar impaction syndrome only addresses TFCC debridement and/or the wafer procedure . Although Palmer et al. described carpal chondral damage in type II lesions, there has been less interest in treating these lesions. In the literature, to our knowledge there is only one study focusing on surgical management of chondral defects within the lunate . In their case series, Kaufman et al. described arthroscopic lunate microfracture technique for Outerbridge type IV chondral lesions and reported good outcomes .
Microfracture technique is an effective treatment for full-thickness chondral defects. The controlled microfracture allows access to bone marrow, which includes mesenchymal and pluripotent stem cells . These cells migrate to the chondral lesion and promote regeneration by forming fibrocartilage that fills the original cartilage defect. While fibrocartilage is less stiff and less resilient than hyaline cartilage, it may provide durable cartilage . It has been reported that the durability of fibrocartilage in weight-bearing joints is worse than the upper extremity joints, as they are more exposed to compressive forces . In addition, non-weight-bearing joints have improved outcomes with fibrocartilage tissue . We believe that the reason for the improvement of symptoms and the absence of progression to ulnacarpal arthritis in our patients may be the successful filling of the defect by fibrocartilage tissue. However, because TFCC debridement and ulnar shortening were also performed in the same procedure, it is difficult to make a definitive conclusion as to which one of these is most effective at improving symptoms.
Significant unloading of the ulnar aspect of the wrist can be achieved after excision of the central portion of the TFCC and resection of the radial two-thirds of the ulnar head . Werner found that excision of 3 mm of subchondral bone decreased the force transmitted across the ulnar head by 50% . Arthroscopic ulnar shortening has the advantage of being less invasive, and is not associated with complications like nonunion . In addition, lunate surface and lunotriquetral (LT) stability can be evaluated arthroscopically. However, if more than 4 mm is required for ulnar shortening, open ulnar shortening osteotomy is recommended .
In this study, we propose a technique that simplifies arthroscopic microfracture. Because a specifically designed awl is not available for the wrist, using a needle as a sleeve enables multiple perforations to be made as close together as possible while maintaining the integrity of the subchondral bone. Unlike the knee or ankle, it is challenging to manipulate the microfracture awl on the lesion during wrist arthroscopy because of the narrow radiocarpal joint space. Using a simple needle to locate the correct entry point to the scaphoid during percutaneous scaphoid fracture fixation has been widely used by hand surgeons. In the same manner, using a needle to localize an accurate entry point for lunate microfracture would make the surgery easier. The major advantage of using a needle over the standard microfracture technique is a greater ability to target defects because of the small joint space of the wrist. Furthermore, in the absence of special tools, an 18G needle can be safely used to perform microfracture.
There are several limitations to our study. Because there was no control group, the clinical improvement may be attributed to the wafer procedure and TFCC debridement. A prospective randomized controlled study would help us to understand whether the clinical improvement was a result of chondral healing or the wafer procedure and TFCC debridement. Using a K-wire for microfracture can be considered another disadvantage because it may cause excessive heat and subsequent progenitor cell death. Finally, we did not confirm chondral regeneration with a control MRI or a second-look arthroscopy.