## 9 Conclusions  
Several emerging techniques for ACL reconstruction surgical enhancement have been reported in the literature. ACL remnant preservation was the most extensively investigated technique, but its beneficial effect differs depending on the assessed outcomes. ACL reconstruction with a pedunculated hamstring graft provides superior revascularization of the graft along with its higher mechanical strength. The usage of a graft enveloped with a periosteum is proposed to enhance the tendon-bone unit formation, and consequently, to prevent the bone tunnel widening. The muscle tissue on the graft is a potential source of stem cells. However, an excessive amount may weaken whole graft strength despite its enhanced remodeling. Similarly, amniotic tissue may augment the ACL reconstruction with stem cells and growth factors. Despite several surgical techniques that utilize amnion, the outcomes of these augmentation methods are lacking. Similarly, although the intra-articular transplantation of the synovium on the surface of an ACL were proposed to augment the graft with synovial tissue and blood vessels, the results of this technique have not been reported so far.  
Figure 4: Synovialization enhancement technique with a pedunculated posterior cruciate ligament (PCL) fat pad: (**a**) Pedunculated fat pad (FP) sutured to the anterior cruciate ligament (ACL) graft (G) with an PDS suture; (**b**) Central part of a graft covered with a fat pad; (**c**) Formation of a hematoma on a surface of the graft after tourniquet release.  
Figure 5: The PCL fat pad technique combined with the distal anterior cruciate ligament (ACL) remnant preservation: (**a**) The fat pad (FP) and the distal remnant of a native ACL (R) adjacent to the ACL graft (G); (**b**) Entire ACL graft covered with the fat pad and the distal remnant of a native ACL.  
Despite the fact that the analyzed methods are easily applicable in routine practice, the evidence supporting their use is still lacking. The underlying premises, derived from the results of basic scientific studies, are promising. However, the majority of presented techniques have not been evaluated in clinical trials so far. Even so, the heterogeneity related to patient characteristics, surgical technique, graft type and fixation method precludes one from drawing definitive conclusions regarding their clinical utility. Specific randomized controlled trials, isolating the influence of the enhancement methods, are urgently needed to characterize their outcomes and describe the indications for their use.  
Conceptualization, M.E. and K.M.; methodology, M.E.; investigation, M.E., M.M. and A.G.; writing--Original draft preparation, M.E., M.M. and A.G.; writing--Review and editing, K.M. and R.F.L.; supervision, K.M. and R.F.L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Data sharing not applicable.  
[PERSON], [PERSON] and [PERSON] report no conflicts of interest. [PERSON]. [PERSON] serves as a Consultant and receive royalties from Arthrex, Ossur and Smith and Nephew and serves on the Editorial Boards of AJSM, JEO and KSSTA. [PERSON] serves as a Zimmer Boimet Consultant, PTArtro Board.