distal clavicle fractures associated with partial and complete coracoclavicular ligament disruption are potentially unstable , and non - operative treatment of these fractures is associated with a high non - union rate.[13 ] partial ligament disruptions ( conoid or trapezoid ) retain some inherent stability , and should be distinguished from complete dual ligament disruptions that result in an uncommon and highly unstable subgroup . internal fixation of these fractures necessitates the use of acromioclavicular joint spanning implants ( clavicle hook plate , synthes , usa ) that overcome distraction forces by subacromial leverage ; however , subacromial / acromioclavicular joint encroachment with these implants is associated with subacromial pathology , and this may negatively influence the final outcomes . to overcome the shortcomings of the joint - spanning implants , acromioclavicular joint - sparing implants ( 2.4 mm lcp distal radius plates , synthes , usa ) have been suggested . additionally , a combination of this implant with some form of coracoclavicular fixation using sutures / anchors / endobutton devices ( tightrope , arthrex , fl , usa ) has been recently described for use in the highly unstable fracture subgroup . however , comparative clinico - radiological outcomes of the two techniques are lacking in literature . the purpose of this study was ( 1 ) to analyze the overall and comparative clinico - radiological outcomes ( radiographic and ultrasonographic ) of surgical treatment of distal clavicle fractures associated with complete coracoclavicular ligament disruption , and ( 2 ) to identify and analyze radiographic patterns of fracture and comminution that are associated with this injury . the hospital records of all patients who were surgically treated for lateral clavicle fractures between 2005 and 2008 at three hospitals were retrospectively evaluated to identify the study group . inclusion criteria for this study was defined as : ( i ) acute , isolated , non - comminuted and comminuted fractures of the lateral clavicle , ( ii ) complete disruption of both coracoclavicular ligaments , confirmed on radiographs and at surgery , ( iii ) absence of concomitant or pre - existing subacromial pathology ( rotator cuff tears , acromial undersurface degeneration ) , ( iv ) surgical treatment with either a joint - spanning implant alone ( group 1 ) , or combination of a joint - sparing implant and coracoclavicular fixation with either endobutton device , suture anchor , or coracoid cerclage ( group 2 ) [ figures 1a and b ] , and ( v ) follow - up period of at least 6 months for radiographic evidence of union . exclusion criteria was defined as : ( i ) partial disruption of the coracoclavicular ligaments at surgery , ( ii ) subacromial pathology ( iii ) concomitant injuries to the ipsilateral shoulder girdle , ( iv ) surgical treatment with any technique other than those described in the inclusion criteria , and ( v ) follow - up period inadequate for complete union . surgical treatment of an unstable distal clavicle fracture with a joint - spanning implant ( group 1 ) . ( hk : hook plate , cl : clavicle , m : medial fragment , l : lateral fragment , arrow : fracture line , ac : acromion , h : humeral head , co : coracoid process ) surgical treatment of an unstable distal clavicle fracture with a joint - sparing implant and coracoclavicular ligament reconstruction using endobutton device ( group 2 ) . ( rp : locking distal radius plate , arrow : acromioclavicular joint , ac : acromion , cl : clavicle , en : endobutton , h : humeral head ) the clinical records and operative notes were analyzed to identify patients that satisfied the criteria described above , and all other lateral clavicle fracture patients were excluded . pre - operative radiographs of the study group were obtained and analyzed with a graphic analysis software ; fracture lines were traced to identify involvement of the acromioclavicular joint , lateral fragment integrity , and presence / absence of comminution . the follow - up clinical protocol included a subjective evaluation of pain and functional status by interview , evaluation of active and passive range of motion by clinical examination , and evaluation of muscle strength in elevation and external rotation using a portable dynamometer . clinical acromioclavicular joint tests ( tenderness and paxinos sign ) and rotator cuff tests ( lag signs , bear - hug test , impingement signs ) were used to evaluate these structures.[811 ] clinical outcome measures included ( i ) simple shoulder test , ( ii ) constant and murley shoulder score , and ( iii ) walch acromioclavicular joint score . the follow - up radiographic protocol consisted of standardized radiographs that included a true glenohumeral anteroposterior view ( neutral rotation , elbow by the side ) , and a weight bearing comparative cephalic - tilt view ; these were analyzed for implant migration , acromioclavicular joint pathology ( degeneration , instability ) , subacromial changes ( degeneration , osteolysis ) , acromiohumeral interval measurement ( normal interval = 7 mm or more ) , peri - coracoid changes ( abnormal bone formation ) , and glenohumeral changes . in addition , in those cases where implant had been previously removed , past radiographs were obtained from the records and individually analyzed as described above . the follow - up ultrasonographic protocol included evaluation of the acromioclavicular joint , subacromial space , glenohumeral joint , bicipital groove and biceps long tendon , and suprascapular and spinoglenoid notches ; ultrasound assessment was performed by a senior radiologist experienced in shoulder ultrasound . statistical analysis was performed using a statistical software ( spss inc , chicago , usa ) to determine mean values and range of measured parameters of the overall and implant specific groups . significant differences between clinical and radiological parameters were determined using the non - parametric mann - whitney / wilcoxon rank - sum test for numerical data , and the fisher 's exact test for categorical data . the average age of the patients in the study group was 34.5 years ( range , 20 to 57 years ) . the mechanism of injury was a direct impact to the ipsilateral shoulder sustained during a fall ; in 8 patients , the fracture was sustained during a cycling - related sporting activity ( competitive or recreational ) . ten patients were operated using a joint - spanning implant ( group 1 ) and 5 were operated using a joint - sparing implant technique ( group 2 ) . the mean follow - up period was 26.1 months ( range , 12 to 40 months ) . the overall and group - specific clinico - radiological outcomes and the types and distribution of fracture patterns are summarized in table 1 . overall and group.specific clinico.radiological outcomes and fracture patterns clinical outcomes : the mean cs was marginally higher in group 2 , while the mean sst score was marginally higher in group 1 ; none of these differences were statistically significant . acromioclavicular joint signs were positive in half of the group 1 patients , and in none in group 2 ; however , the walch scores for the acromioclavicular joint were not significantly different for the two groups . return to pre - operative level of recreational and competitive sports was seen in approximately two - thirds of the patients of group 1 , and all patients of group 2 ; this difference was not found to be statistically significant . reoperation rates related to implant removal were significantly higher ( p < 0.05 ) in group 1 patients ( 90 % ) as compared to group 2 ( 0% ) . radiographic outcomes [ figure 2a - d ] : radiographic union was observed in 93.3% of fractures ( 9 in group 1 , 5 in group 2 ) with only one non - union with subsequent fragment resorption ( group 1 ) . radiographic acromioclavicular joint degeneration was present in 3 patients ( group 1 ) ; all 3 patients had a clinically symptomatic ac joint . radiographic acromioclavicular joint superior subluxation was present in 4 patients ( group 1 = 1 patient , 10% ; group 2 = 3 patients , 60% ) ; none of these were clinically symptomatic . subacromial osteolysis and hook migration were seen in 5 patients ( group 1 ) ; implant removal was necessary in 4 of these 5 patients , and at final follow - up , resolution of the radiographic subacromial osteolytic lesions was observed . signs of progressive implant loosening ( screws and/or plate disengagement ) were seen in 3 patients ( group 1 ) . abnormal bone formation was present in 7 patients ( group 1 = 6 , group 2 = 1 ) . ( b ) acromioclavicular joint subluxation ( arrows ) , ( c ) hook migration and osteolysis of acromial undersurface ( arrow ) , ( d ) peri - coracoid ossification ( arrows ) . ( ac : acromion , cl : clavicle , co : coracoid , p : plate , an : suture anchor , g : glenoid , h : humeral head , hk : hook plate , ahi : acromiohumeral interval ) ultrasonographic outcomes [ figure 3a and b ] : supraspinatus lesions were seen in 3 patients ; these included partial articular - side tears ( group 1 = 1 patient , 10% ; group 2 = 1 patient , 20% ) , and supraspinatus bursal - side degenerative changes ( group 1 = 1 patient , 10% ) . acromioclavicular joint screw penetration was observed in 1 patient ( group 2 ) ; this penetration was not apparent on plain radiographs and the patient was asymptomatic at the final follow - up . no abnormalities were detected in the subacromial bursa on static ultrasound evaluation ; dynamic testing revealed abnormal subacromial bursal " bunching " with arm abduction in 2 patients ( group 1 = 1 , group 2 = 1 ) . ( a ) partial articular - surface supraspinatus tendon avulsion ( black arrows ) ( b ) screw penetration into the acromioclavicular joint ( arrows ) . ( gt : greater tuberosity , h : humeral head , ss : supraspinatus , ac : acromion , cl : clavicle , asterix : acromioclavicular joint ) radiographic evaluation of fracture comminution revealed 5 non - comminuted fractures ( group 1 = 2 , group 2 = 3 ) , and 10 comminuted fractures ( group 1 = 8 , group 2 = 2 ) . analysis of the fracture lines and fragment cortices revealed repetitive patterns in the fracture geometry , and four types could be identified : ( i ) type 1 pattern ( n = 5 , 33% ) involved a clean vertical or a short oblique type bicortical fracture line without any comminution [ figure 4a ] , ( ii ) type 2 pattern ( n = 4 , 27% ) involved a zone of segmental comminution , between intact bicortical lateral and medial fragments [ figure 4b ] , ( iii ) type 3 pattern ( n = 5 , 33% ) involved propogation of at least one fracture line into the juxta - articular cortex of the ac joint [ figure 4c ] and ( iv ) type 4 pattern ( n = 1 , 7% ) consisted of fracture line propogation into the acromioclavicular joint [ figure 4d ] . radiographic fracture patterns : ( a ) type 1 , ( b ) type 2 , ( c ) type 3 , and ( d ) type 4 . ( ac : acromion , cl : clavicle , co : coracoid , g : glenoid , h : humeral head , arrows : fracture lines ) the present study is the first study that describes overall and comparative outcomes ( clinical , radiographic , and ultrasonographic ) of surgical treatment of an uncommon lateral clavicular bony - ligamentous injury with joint - spanning and joint - sparing implants . in addition , four radiographic patterns of bone injury were identified to develop guidelines for choice of implants in these injuries . clinical outcomes and union rates after operative treatment of this injury are satisfactory , and this has been shown in other studies in literature . in the present study , both types of implants resulted in satisfactory and comparable clinical outcome scores , irrespective of the radiographic outcomes . however , a significant difference in the reoperation rate for implant removal ( p < 0.05 ) in patients treated with a joint - spanning implant probably implies that a joint - sparing implant could be preferentially used whenever fracture geometry permits . radiological outcomes , especially those associated with joint sparing techniques , have not been well documented in other studies . subluxation of the acromioclavicular joint , ( present in 60% of group 2 patients ) may be related to either concomitant injury to the acromioclavicular ligaments , or to a partial failure of the coracoclavicular ligament reconstruction ; transfer of distraction forces to ac ligaments after fracture union may then induce gradual subluxation of this joint . this complication was rare in the other group , probably due to the joint spanning implant design ; however , other radiological abnormalities like hook migration , subacromial osteolysis , implant loosening , and new bone formation were frequent . the acromioclavicular joint spanning hook plate is a commonly used implant , and most studies have utilized this as the sole implant of choice . although clinical outcomes in these studies have been satisfactory , the effect of the subacromial hook on bursal tissues has been debated and use of the distal clavicle plate suggested . by using ultrasonographic evaluation , this study demonstrated the safety of the joint - spanning hook plate in relation to rotator cuff and subacromial bursa . persistent pain in the post - operative period probably resulted from acromial undersurface irritation ; early plate removal after fracture union is recommended , and long - term clinical outcomes seem to be satisfactory after implant removal . an important finding of this study is the grouping of the radiographic fracture patterns into four surgically relevant types . types 1 and 2 are ideal indications for use of a joint - sparing implant ; adequate bone stock in the distal fragment in these types will theoretically permit secure fixation across the fracture site . in types 3 and 4 , inadequate distal fragment size may not permit secure bicortical fixation , thereby necessitating use of joint - spanning implants . . the retrospective nature and small sample size does not permit identification of all possible fracture configurations , and statistical analysis may differ with larger numbers . however , the clinical results are similar to other literature studies that have analyzed joint - spanning implants . also , the current radiographic patterns described provide guidelines for implant choice , and are not intended to be used as a prognostic classification . we attribute the small size of the study group to the stringent inclusion and exclusion criteria that eliminated several other patients with lateral clavicle fractures , and this was necessary to obtain meaningful conclusions . lateral clavicle fractures with complete disruption of the coracoclavicular ligaments should be regarded as a distinct entity that is perhaps biomechanically and prognostically different from similar fractures with partial ligament disruption . a combination of a locking distal radius plate with coracoclavicular ligament reconstruction resulted in stable fixation and significantly lower reoperation rates , and should be used preferentially in lesser comminuted fractures ( types 1 and 2 ) .
purpose : distal clavicle fracture associated with complete coracoclavicular ligament disruption represents an unstable injury , and osteosynthesis is recommended . 
 this study was performed ( 1 ) to retrospectively analyse the clinico - radiological outcomes of two internal fixation techniques , and ( 2 ) to identify and analyse radiographic fracture patterns of fracture that are associated with this injury.materials and methods : a total of 15 patients underwent osteosynthesis with either ( 1 ) acromioclavicular joint - spanning implants ( group 1 , hook plate device , n = 10 ) or ( 2 ) joint - sparing implants ( group 2 , distal radius plate , n = 5 ) ; these were reviewed at a mean period of 26.1 months ( 12 to 40 months ) . 
 clinical outcomes were measured using constant score ( cs ) , simple shoulder test ( sst ) , and walch acj score ( ws ) . 
 radiographs and ultrasonography were used to assess the glenohumeral and acromioclavicular joints , and the subacromial space . 
 preoperative radiographs were analyzed for assessment of fracture lines to identify radiographic patterns . 
 statistical analysis of the data was performed to determine any significant differences between the two groups.results:the overall clinical outcome was satisfactory ( cs 80.8 , sst 11.3 , ws 17.6 ) and a high union rate ( 93.3% ) was observed . 
 radiographic complications ( acromioclavicular degeneration and subluxation , hook migration , abnormal ossification ) did not negatively influence the final clinical outcomes . 
 four distinct radiographic fracture patterns were observed . 
 a statistically significant difference ( p < 0.05 ) was observed in the reoperation rates between the two groups.conclusions:internal fixation of this fracture pattern is associated with a high union rate and favorable clinical outcomes with both techniques . 
 a combination of distal radius plate and ligament reconstruction device resulted in stable fixation and significantly lower reoperation rates , and should be used when fracture geometry permits ( types 1 and 2).design : retrospective review of a consecutive clinical case series.setting:level 1 academic trauma service , public hospital .