Background Currently,the clinical perspectives of surgical treatment for Tossy Ⅲ acromioclavicular(AC) joint dislocations are relatively identical.Due to the post-traumatic ruptures of the acromioclavicular ligament and coracoclavicular(CC) ligament which are used to maintain stability of the joint,the clavicle moves backward and upward,and the upper arm and the scapula drops downward for the gravity of the upper arm and the influence of the sternocleidomastoid muscle.Since such complications as reduction difficulties,redislocation after external fixation,pressure ulcers of the skin,and so forth are particularly prone to occur in the conservative therapy,the operative treatment is more inclined to be adopted for the Tossy Ⅲ dislocation of the AC joint.With the single repair and fixation of the CC ligament,redislocation is likely to happen after implant removal because the ruptured ligaments healed as scar tissue.Therefore,this study uses an operative method of reconstructing and augmenting the CC ligament with LARS artificial ligament for the treatment of Tossy Ⅲ AC joint dislocation,and evaluates its clinical effect.Methods From November 2006 to July 2009,8 patients with acute AC joint dislocation of Tossy Ⅲ were admitted into our hospital.Five patients were male and 3 were female,and their ages ranged from 21 to 45.Sides:3 injuries were on the left and 5 were on the right.Seven patients suffered from falling on the ground,and 1 patient was injured in a traffic accident.All the patients were treated with LARS artificial ligaments to reconstruct the CC ligament.Constant score and VAS score were adopted in clinical evaluation.Zanca view of the bilateral AC joint and the axillary radiograph of the affected shoulder joint were employed for imaging evaluation.All the patients were simple Tossy Ⅲ dislocation of AC joint with no trauma of other parts and skin breakdown.Regular pre-operative examinations and evaluations were carried out after admission,and LARS artificial ligament was used to reconstruct the CC ligament.Surgeries of all the patients were performed under general anesthesia within 2 to 5 days after injury,and the operation time ranged from 60 to 90 minutes.After successful anesthesia,the patient lied on a beach chair position with the affected shoulder bolstered up.Attachment points of trapezoid ligament and conoid ligament are evaluated preoperatively through the length of clavicle among all the patients.The incision is made along the affected acromion and distal clavicle,curved downward to expose the clavicle and the tip of coracoid process.Find the ruptured CC ligament and then repair it with absorbable stiches by mattress-suture,leaving the reserved sutures unknotted.Then reconfirm the attachment point of CC ligament is on the location of coronal section,and if possible,the location can be identified by the exposure of CC ligament.Drill a hole separately with a diameter of 4.5 mm bit,and make sure that the drilling position is in the sagittal plane close to the front on the premise of intensity.Make the LARS artificial ligament pass through the root of coracoid with a drilling guide,and thread the two ends of ligament through the clavicular bone tunnel.After the confirmation of satisfactory reduction,tighten up the artificial ligament and fix the interference screws.Weave and knot the two sides of the ligament,suture with non-absorbent stitches and cut off the redundant part.Strain the absorbable suture on CC ligament and tie a knot.The routine anti-infection treatments were given and the affected arm was slung with scarf bandage.The patient was told to carry out functional activities of fingers and the forearm postoperatively.Active mobilization of the shoulder was initiated after 3 days and regular movements were in process without scarf bandage 3 weeks later.Such strenuous activities as physical exercise were forbidden within 3 months.Constant score and VAS score were adopted in clinical evaluation.Zanca view of the bilateral AC joint and the axillary radiograph of the affected shoulder joint were employed for imaging evaluation.Results All the patients were followed up for 5 to 40 months.Constant score of the affected arm increased from (59.3±6.9) preoperatively to (96.5±9.3) postoperatively (T=300,P<0.05),and VAS score decreased from (5.4±1.3) preoperatively to (0.7±0.9) postoperatively (T=300,P<0.05).Zanca view of the bilateral AC joint revealed that 7 patients had an anatomical reduction,except for one patient with slight loss of reduction.No re-dislocation occurred.Two cases of CC ligament calcification and one case of AC joint degeneration were found,and no osteolysis around the interference screw was detected.No shift of the distal clavicle in the horizontal direction was found in the axial view,and neither was backing out of the screws,the clavicular fracture,or the coracoid fracture.Discussion AC joint is a non-typical ball-and-socket joint,the center of which is located between the AC joint and the CC ligament.The stability of the distal clavicle mainly depends on the integrity of CC ligament.The optimal method for dislocation of the AC joint is to reconstruct the CC ligament,which is decided by the anatomical characters of the AC joint.Otherwise,redislocation might still occur after the removal of the internal fixator even if the AC joint is reduced.Previous primary principle of the operation method was the repair of CC ligament with the fixation of AC joint at the same time.However,single repair of the ligament had a low healing rate,and the scar tissue of the ligament hardly bore the tension required for the early functional exercise.Hence,after a long period of recovery procedure,patients suffered from different degrees of functional incapacitation,which postponed their schedule of returning to work.Some scholars afterwards started using the method of ligament reconstruction to perform the surgery.Autografts and allografts are sources for ligament reconstruction.The process of necrosis,revascularization,cell multiplication,and ligamentization is needed for autogenous grafts,which will take around 1 year.Therefore,proper limitation of patient’s early activities is inconsistent with our original intentions of early training to reduce the loss of function.Laxity of grafts is likely to be observed during the late period with decreased stretching resistance,and still has difficulty in avoiding osteoarthritis eventually.With the development of the material technology subsequently,we start the operation of repair and reconstruction with the application of artificial ligament.Compared to autologous and allogeneic grafts,artificial ligament has obvious advantages:(1) Less injury:The trauma is decreased since there is no need for the surgery to harvest tendons from his or her own body.(2) Quick recovery:Artificial ligament has a certain degree of the mechanical strength without necessities of the process of necrosis,revascularization,cell multiplication,and ligamentization inside the body.Accordingly,the application of artificial ligaments shortens the recovery time with less medical resources and society costs.We adopt the French LARS polyester fiber ligament of bracket type as our surgical materials for this study.This kind of ligaments has features as follows:(1) Higher biocompatibility:The PET polyester fiber is identical with sutures and artificial blood vessels and has excellent biocompatibility,the free fiber inside which can induce the ingrowth of fibrous connective tissue of the human body itself.(2) Pass the “tension-bending-torsion” hybrid test:It may bear the pulling force of 5000 Newton.(3) Preserve the intraoperative remnant tissue of the ligament and keep the physiological proprioception.From the points above we can see that:The permanent-stent ligament we adopt had good histocompatibility and can provide excellent tensile resistance.The micropores of 30～50 μm inside the fibers are suitable for the ingrowth of the autologous connective tissue,and can play the role of “support”,not only as physical remediation,but also with the function of the biological tissue engineering repair.This ligament can provide better early strength in the initial stage,and is able to withstand the intensity required by patients’ early functional training.The ultimate intensity will be ensured with the ingrowth and restoration of the autologous tissue in the late stage.The restorative procedure is a kind of physiological reconstruction,which can also be applied for obsolete dislocations.Hence,the permanent-scaffold ligament is an effective method for the treatment of AC joint dislocations,especially the old dislocation.The key issue of the ligament reconstruction is how to determine the location and direction of drilling on the clavicle.Since it is ligament reconstruction,we consider that it is the most consistent with physiological features as the prosthetic ligament travels along the walking direction of the original one,which can maximally guarantee the ingrowth of the human tissue into the artificial ligament to achieve its physiological reconstruction.This prosthetic ligament has limitations as well.First,it is expensive,which restricts its extensive application in the current situation of China.Second,fixation of the ligament mainly relies on interference screws,and it is not suitable for the patients with osteoporosis.Once again,the objective of the use of artificial ligaments is to restore patients’ preoperative function to the maximum extent.Therefore,artificial ligament is not most suitable for patients who have the loss of preoperative function or patients with not-so-high requirement for function.We consider that the technology of CC ligament reconstruction with LARS artificial ligament is a feasible method in the treatment of the AC joint dislocation.Such ligament can offer credible strength in the early period,which provides a preferable biomechanical environment for the primary healing of the CC ligament,and the merits of the ligament of bracket type reliably assure the preservation of the repair strength in the late stage.In addition,the advantage of artificial ligaments is unnecessary to remove implant by a second surgery,which decreases the patient suffering and financial burdens.Conclusions CC ligament reconstruction with the LARS artificial ligament can offer reliable early strength for AC joint,and it allows early functional training of patients.This enables patients to acquire better clinical outcome and less complication.