Letter to the editor: Donor site morbidity of free ulnar forearm flap—absent or not found?

Abstract

methods and study design obtained controversial results. Considering only common features assessed in both studies and only those of crucial impact on daily life of patients, grip strength reduction after UFF harvest may be of special interest. This donor-site morbidity was “NEVER” observed in the collective investigated by Tan et al. 1 Careful reading of the Methods’ section, especially in view of patients’ sample evaluated for functional impairment—actually the results have to be considered here— will reveal that most, if not all patients had their donor site directly closed. It is thus all the more surprising that none of these patients had any grip strength deficit compared to the contralateral limb. In contrast, we assessed reduction of grip strength in 30% to 57% of patients in our study. Neither of these studies was performed prospectively; thus, primary values of grip strength of donor limb are missing and comparison with the contralateral limb is only valid if both hands primarily showed similar grip strength. This is usually not the case, and in a retrospective study design, such as that used for both reports, the grip strength will always show better results when the UFF is harvested from the dominant forearm. If one assumes that the nondominant limb was chosen for UFF harvest in the present study—this is not clearly reported—the differences to our results are all the more surprising. Trying to understand and to explain the differences revealed by this comparison, the key point of discrepancy may focus on flap design. As shown in Figure 4 of the article 1 and explained as representative in the discussion, UFF was harvested more proximally than usually performed. Skin in this part of the forearm is elastic and skin excess, particularly in elderly patients, enables tension-free closure without extended undermining or circular constriction, such as that taking place on the distal part of the forearm. At this point, it is now no wonder how direct donor site closure in the present article implicated far less reduction of grip strength than in our study in spite of a similar number of patients. According to our experience, UFF harvest, like the radial pendant, 3 may reduce grip strength in a considerable number of patients who should be informed about such donor-site morbidity. It is not well known how UFF harvest may reduce grip strength, but one of the potential factors aggravating this side-effect is the kind of skin closure. Direct closure in primary intention requires undermining of adjacent skin and produces tension and circular constriction at the distal part of the forearm and may contribute to grip strength reduction.