## 4 Discussion
### MIMO Complications  
This review showed an overall complication ranged between 44.9 and 68.2%. The most frequent complications were swelling (56.3%) reported in one study [27], radiographical nonunion (4.5-30.0%), infections (3.3-31.8%), transfer lesions (9.1-26.5%) and ulcer recurrences (0-13.6%). Radiographical non-union, although very frequent, was reported in four studies (range 4.5-30.0%) and in all cases described as asymptomatic [29; 38; 40; 41], probably because of sensory neuropathy. Only in [PERSON]'s study, a fixation was used to prevent nonunion, using temporary K-wires or cancellous bone screws [38]. However, as expected by the presence of metalwork, the technique was burdened by a higher infection rate (31.8%) compared to the other studies. Infections often adversely affect the healing of PDFUs. Infection rate was reported in five out of 8 studies and ranged from 4.2 to 25.2% [27; 30; 38; 40; 41]. They were mainly treated successfully with oral or intravenous antibiotics. Only six cases, reported in three studies [27; 38; 41], required subsequent surgical treatment to eradicate a deep infection. Wound discharge rate was reported only in one study and was computed at 23.8% [39]. Similarly, necrosis rate was reported only in one study and was 4.8% (one case of necrosis of the fifth toe related to the casting, resulting in the amputation of the toe) [39]. Transfer lesions were reported in six studies (range 9.1-26.5%) and usually described under the heads of the adjacent metatararsals [29; 30; 38; 40; 41]. These lesions occur when a correct metatararsal parabola is not re-established in the forefoot [6]. In two studies, transfer lesions were reported to appear at a mean of 10 and 7.5 months, respectively, (after the osteotomy procedures) [30; 40]. This is probably due to the resumption of patients' normal walking and incorrect overloading of the lateral metatarsal bones. The highest transfer lesion rate (26.5%) was found in the report by [PERSON] et al. (1990) [29] (excluding the case report of [PERSON] (1986) [35]), but considering all of the other papers, the transfer lesion rate was 17%. The recurrence/relapse pooled rate of the ulcers was 7.2%. It has to be considered that this rate is higher in the first studies related to the 90s [29; 38], while thereafter only 1 case was described by [PERSON] et al. 2021 [41]. Only four patients needed an off-loading redo -surgery; the only other cases that required further surgery are the six patients who had deep infections. Swelling rate was reported only in one study, where 18 out of 32 feet were found to be swollen [27]. Swelling rate was computed to be 56.3% and was persistently moderate, affecting the forefoot for more than 6 weeks without infection, which improved after some months with complete callus formation at the osteotomy levels and without further treatment. Finally, acute Charcot foot, the most fearsome complication, was reported only by [PERSON] et al. (1999) in seven cases (31.8%), who were traditionally treated by serial total contact casting until the resolution of the acute inflammatory process and bony consolidation identified by radiographs [38]. The eight studies considered had a total population of 189 patients; however, regarding the clinical outcomes and complications, statistical analysis presented a heterogeneity that was not statistically significant (except in the case of the healing rate and overall complication rate analysis). Although the outcome measures of the eight papers included in this review presented an outstanding healing rate of 91.9% (ranging from 74.9 to 97.8%), in the 1990s, [PERSON] et al. [26], who recruited the highest number of diabetes type 1 patients (coefficient = 0.0522 (SE = 0.0102), \(p\) = 0.0000) and performed a variety of surgical procedures (Q = 27.24, \(p\) = 0.0000) reported the lowest healing rate. However, these moderators were not significant with the multivariate meta-regression analysis.