New trends in ACL research

Abstract

ACL research has driven ACL surgery and, throughextensive work over the past 10 years, clearly established‘‘anatomic ACL reconstruction’’. At the recent PantherGlobal Summit (Pittsburgh, PA, USA, August 25–27,2011), 24/28 (85%) experts utilized anatomic techniquesfor ACL reconstruction. In contrast, 70% of a global expertpanel in the year 2000 preferred the transtibial techniquefor ACL reconstruction [8].While the past 10 years in ACL research were dedicatedto the rediscovery of double-bundle ACL reconstruction,the more recent past research is dedicated to identifyingcriteria for anatomic single bundle versus anatomic double-bundle ACL reconstruction. An important part of therediscovery is the treatment algorithm for anatomic ACLreconstruction by Fu et al. [14]. The most commonly listedindications for double-bundle ACL reconstructions are (1)large insertion sites ([18 mm tibial ACL anteroposteriordiameter), (2) wide notch width ([12 mm), (3) high-gradepivot shift, and (4) revision ACL reconstruction. There areestablished contraindications for double-bundle ACLreconstruction, such as (1) multi-ligament injuries, (2) openphyses, (3) degenerative OA, (4) small insertion sites(\12 mm tibial anterior–posterior diameter), and (5) smallnotch width (\12 mm). It is noteworthy that there are nocontraindications for anatomic ACL reconstruction.A considerable amount of research is being done in thefield of ACL remnant preservation. In contrast to the1990s, when non-anatomic guides were most commonlyused for tunnel placement, it is now widely recognized thatanatomic ACL reconstruction demands adequate identifi-cation of anatomical landmarks, such as the femoral ridgesand the footprints on the tibia and femur, respectively [6,15]. Preservation of the native ACL remnants is further-more shown to enhance biomechanical knee stability [11],as well as provides mechanoreceptors that potentiallyimprove proprioceptive function following ACL recon-struction [1]. At the recent Panther Global Summit, 20/28(68%) experts preserve remnants during ACL reconstruc-tion surgery.Musculoskeletal imaging has improved in many ways.MRI is not only used for diagnosis and pre-operativeplanning purposes, but it can be used post-operatively forthe assessment of ACL graft healing and development ofosteoarthritis. MRI can also assist in accurately identifyingACL injury patterns [2, 13]. The utilization of post-oper-ative radiographs is still the most common modality toassess adequate tunnel placement. However, 3-D CT issuperior to radiographs and more clearly reflects the intra-operative perspective of the arthroscopic surgeon. 3-D CTprovides a critical assessment of accurate tunnel placement[7, 10].There is, and has been, much hype about biologicalenhancements for ACL healing and/or reconstruction.However, hardly any treatments have made a clinicalimpact beyond in vitro- and animal research. One of thefew approved treatments is growth factor therapy in theform of autologous fibrin clots or platelet-rich plasma(PRP). A fibrin clot between the two grafts for double-