Surgical treatment of chronic acromioclavicular dislocation with biologic graft vs synthetic ligament: a prospective randomized comparative study
© The Author(s) 2013
Received: 19 April 2012
Accepted: 9 April 2013
Published: 7 May 2013
Acromioclavicular (AC) dislocation involves complete loss of articular contact; it is defined as chronic when it follows conservative management or unsuccessful surgical treatment.
Materials and methods
The study compared the clinical and radiographic outcomes of AC joint stabilization performed in 40 patients with chronic dislocation using a biological allograft (group A) or a synthetic ligament (group B). Demographic data included: M/F: 25/15; mean age: 35 ± 3.2 years; previous surgery in 11 patients, including Weaver–Dunn (3), coracoacromial ligament repair (4), stabilization with K-wires (4). Dislocation was type III in 14 (35 %) and type IV in 26 (65 %) patients. Clinical assessment was with the Constant–Murley score (pre- and postoperative) and with the modified UCLA score. Enrollment started in January 2004 and was completed in March 2008. Patients were evaluated at 1 and 4 years. Postoperative X-rays were examined to assess joint stability in the coronal and axial planes, coracoclavicular ossification, and signs of AC joint osteoarthritis and distal clavicular osteolysis.
The “biological” group achieved significantly better clinical scores than the “synthetic” group at both 1 and 4 years. Poor subjective satisfaction and lower clinical scores were found in the 3 patients (1 from group A and 2 from group B) who experienced complete postoperative dislocation. No significant correlations were found with other radiographic parameters.
The biological graft afforded better clinical and radiographic outcomes than the synthetic ligament in patients with chronic AC joint instability. Fixation to the clavicle constitutes the main weakness of both approaches and needs improving.
Acromioclavicular (AC) dislocation involves complete loss of articular contact; a dislocation that is not untreated, is treated conservatively or is treated unsuccessfully by surgery is defined as chronic or inveterate [1, 2]. The AC and coracoclavicular ligaments contribute to anterior–posterior and superior–inferior joint stability, respectively . Complete instability requires rigid fixation of the coracoclavicular ligaments to counteract the AC joint laxity that induces posterior translation of the clavicle. The classification of AC dislocation into 6 degrees of severity, as devised by Rockwood et al. , is still the one most commonly used. While there is consensus on the conservative treatment of types I and II, there is still debate over whether types III to V should be managed surgically [5, 6]. Among the surgical approaches developed to treat acute and chronic AC dislocation, some authors [5, 16, 17, 31] have recommended procedures that restore the original joint anatomy and congruity ; a number of these techniques use biological or synthetic means [8, 9].
This study compares the clinical and radiographic outcomes of surgical AC joint stabilization performed in 40 patients with chronic dislocation using a biological graft or a synthetic ligament.
Materials and methods
This was a prospective randomized clinical study that was designed to ascertain the results of AC joint stabilization using two systems of fixation. All of the patients gave informed consent prior to being included in the study, which was authorized by the local ethical committee (Cometico AV/IRST no. 4442/C012/I5/169) and was performed in accordance with the Ethical Standards of the 1964 Declaration of Helsinki as revised in 2000.
Randomization and sample size
The intent-to-treat population included 40 patients who were fully randomized using a block list that was generated by dedicated software (Research Randomizer, version 3.0, 2011). Envelopes containing the treatment assignments were used to randomize the patients in the two groups. A power analysis was performed in which a 7-point difference in the Constant score between the two groups was required, and a standard deviation of 6 points. Using these parameters, it was calculated that a minimum of 38 subjects were needed.
Demographic data for the patients enrolled in the study
No. of patients
Mean age (years ± SD)
36 ± 4.3
34 ± 2.8
Dominant arm (right/left) (%)
Overhead workers (N°) (%)
Previous surgery (N°) (%)
Degree of dislocation
Eleven patients (27.5 %) had undergone surgical treatment at other institutions as follows: Weaver–Dunn procedure, 3 patients (5 %, 1 in group A and 2 in group B); coracoacromial ligament repair with non-absorbable suture, 4 patients (10 %, 2 in group A, 2 in group B); stabilization with K wires, 4 patients (all group B). All patients complained of pain involving the AC joint and the trapezius that worsened with cross-arm adduction. Active ROM was full in all patients. Weakness beyond 90° of elevation was seen in 5 patients (12.5 %, 2 in group A and 3 in group B). Patients were examined for keloids, AC joint deformity, pain on palpation or during passive mobilization in forward elevation and forced adduction, and joint instability during active mobilization. The Constant–Murley score  was used for clinical assessments before and after the operation and the modified UCLA score  was employed after the operation. This study required that clinical follow-up was performed at 1 and 4 years.
AP and axillary views were examined to assess AC joint stability in the coronal and axial planes, coracoclavicular ossification, signs of osteoarthritis, and distal clavicular osteolysis. X-rays were routinely performed at 2 months; for the requirements of the current study, additional radiograms were taken at 1 and 4 years. Postoperative AC joint stability was assessed according to Rosenorm and Pedersen ; the AC joint was considered to be stable if it showed no dislocation compared to the contralateral joint; subluxated if the dislocation was ≤50 % of the contralateral joint; or dislocated if there was complete dislocation accounting for ≥100 % of the AC joint surface.
Coracoclavicular ossification was deemed incomplete if there was no continuity between clavicle and coracoid process, and complete if it obliterated the coracoclavicular space.
Arthritis was considered to be present if the joint showed joint space narrowing, osteophytes, or sclerosis. Clavicular osteolysis was defined as signs of demineralization around the screws or on the lateral portion of the clavicle.
Clinical scores were expressed as the mean ± standard deviation. Student’s unpaired t test was applied to assess differences between the two groups. Significance was set at 5 % (p < 0.05).
Preoperative and postoperative clinical scores
43.5 ± 6.1
44.05 ± 8.9
88 ± 10
59 ± 7.9
94.2 ± 4.9
85.9 ± 16
Modified UCLA score
17.8 ± 1.8
11.8 ± 4.9
18.2 ± 1.7
15.4 ± 4.2
8.7 ± 3.4
8.4 ± 2.6
3.7 ± 1.6
4.1 ± 1.5
3.9 ± 1.8
3.9 ± 1.4
Group B: the mean Constant–Murley score rose from 44.05 ± 8.9 to 59 ± 7.9 at 1 year (p = 0.0049) and to 85.9 ± 16 at 4 years (p = 0.0089). The mean UCLA score was 11.8 ± 4.9 at 1 year and 15.4 ± 4.2 at 4 years (Table 2).
Subjective satisfaction was good in 17 patients (85 %) from group A and in 14 patients (55 %) from group B. A significant improvement was registered for both groups at 1 year (p = 0.011 and at 4 years (p = 0.014). None of the 40 patients had to change their habits after the operation due to the clinical outcome, including returning to sports or a job.
We did not find a significant difference between the 11 patients previously treated surgically and the study population in their clinical scores and subjective satisfaction.
Postoperative radiographic findings
AC joint arthritis
AC joint arthritis
Subjective satisfaction was not related to the degree of AC joint reduction. Although early postoperative radiographs showed partial loss of AC joint alignment in 3 patients (15 %) from group A and in 6 (30 %) from group B, poor satisfaction was only reported by 4 group B patients (20 %).
At 4 years, <50 % partial dislocation (subluxation), which was found in 4 patients from group A (20 %) and in 4 from group B (20 %), did not correlate with the clinical scores (p > 0.05). Poor subjective satisfaction and lower clinical scores were found in the 3 patients (1 from group A and 2 from group B) who had experienced complete joint dislocation after the operation. No correlation was found between clinical score and coracoclavicular ossification, clavicular osteolysis, or AC joint osteoarthritis.
From 1861  to the present, 60 different surgical procedures have been devised to treat acute and chronic AC joint dislocation, but finding the gold standard has proved an elusive task. In 1972, Weaver–Dunn  proposed the transposition of the coracoacromial ligament to the lateral portion of the clavicle. This approach involves sacrificing the coracoacromial ligament (a humeral stabilizer). The interest in this type of technique, which is based on the assumption that AC joint reduction and anatomical restoration provide more satisfactory outcomes , has recently been revived by the introduction of synthetic ligaments [17, 18] and biological grafts [16, 19]. Techniques based on the transposition of the patient’s tendons that show resistance to cyclic loading, similiar to rigid osteosynthesis (screws, plates, pins, metal or synthetic cerclage) [20, 21] but with lower rates of intra- and postoperative complications, were developed to address these problems [8, 19, 22–24]. Bailey  was the first to report the results of tendon transposition; Dewar and Barrington  used only coracoid transposition and obtained better mid-term outcomes compared with the Weaver–Dunn procedure in young patients . Although transposition of the coracoid with the conjoint tendon reinforces the reconstructed coracoacromial ligament, it involves a greater risk of coracoid fracture and musculocutaneous nerve injury; furthermore, bone cerclage may result in coracoid or clavicle osteolysis.
Materials that are used for artificial ligaments include polyester, Dacron®, Dupont®, Wilmington®, Notthingam® [8, 23], carbon fiber , polytetrafluoroethylene (Gore-Tex®) , and PET (LARS LAC®) . The characteristic interwoven fibers and the porosity of the synthetic ligament promote fibroblast colonization and make the ligament biocompatible and resistant to traction and torsion; nonetheless, intolerance, inflammation, and rejection have been described . Tendon autografts or allografts were initially used in salvage procedures after failed coracoacromial ligament reconstruction . The most widely used allografts are semitendinosus , gracilis, hallux extensor , and peroneus brevis tendons . Biocompatibility, resistance, and rigidity of the system used for joint reduction are crucial for postoperative stability in chronic AC joint dislocation.
Although good outcomes of synthetic  and biological grafts  have been (separately) described in several reports, no single study has, to our knowledge, used both materials and compared them. Although anatomical AC joint reconstruction cannot restore original stability to the joint, tendon grafts provide greater resistance and rigidity than the Weaver–Dunn procedure . Analysis of the results of our study disclosed significantly greater clinical scores in the “biological” compared with the “synthetic” group at both follow-up time points, with mean intergroup differences in Constant–Murley score of >29 points at 1 year and >8.9 points at 4 years, and mean differences in modified UCLA score of 6 points at 1 year and 2.8 points at 4 years.
Eleven out of 40 patients were previously surgically treated using different surgical techniques, which affected the articular biomechanics of the AC joint in different ways, and consequently influenced the homogeneity of the study population. In these patients, we found a higher incidence of periarticular ossifications, clavicular osteolysis, and fibrous adhesions intraoperatively, which made it more difficult to expose the clavicle and acromion. Furthermore, the passage of the graft under the coracoid required a longer surgical step due to the thickening of the surrounding soft tissues. Despite these difficulties, we did not find any significant effects on the clinical scores and AC joint stability based on the X-rays for this subgroup of patients.
Postoperative AC joint stability is the main factor affecting final outcome; the best results were recorded in patients with completely stable joints.
Although the synthetic graft is effective from a biomechanical standpoint, graft shredding and wear and bone remodeling around the screws can compromise mechanical strength over time, particularly in elderly patients and in those with poor clavicle bone thickness or osteoporosis.
Biological grafts provide joint stability in the axial and the coronal planes through suture of the lateral stump of the graft to the acromion, a finding confirmed by recent  and earlier  studies; axial stability appears more difficult to restore using a synthetic graft.
Biological grafts are fixed to the clavicle with resorbable screws and are a valuable option when treating patients with postoperative recurrence of dislocation due to synthetic graft failure.
The major limitations of this study are the small sample size, the lack of inter- and intraobserver data, and the absence of patients treated with tendon autografts.
In conclusion, our findings show that biological grafts provide biocompatible, durable, and effective reduction, as well as better clinical outcomes and radiographic findings than synthetic ligaments, and thus represent the most reasonable alternative to the Weaver–Dunn  procedure in shoulders with chronic AC joint instability. Graft fixation to the clavicle is the major weakness of both procedures and should be improved.
Conflict of interest
Open AccessThis article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.
- Clarke HD (2000) McCann acromioclavicular joint injuries. Orthop Clin North Am 31:177–187PubMedView ArticleGoogle Scholar
- Rockwood CA (1984) Injuries to the acromioclavicular joint. In: Rockwood CA, Green DP (eds) Fractures in adults. Lippincott, Philadelphia, pp 860–910Google Scholar
- Fukuda K, Craig EV, An KN et al (1986) Biomechanical study of the ligamentous system of the acromioclavicular joint. J Bone Joint Surg Am 68:434–440PubMedGoogle Scholar
- Rockwood CA Jr, Williams GR, Young CD (1996) Injuries of the acromioclavicular Joint. In: Rockwood CA Jr et al (eds) Fractures in adults. Lippincott-Raven, Philadelphia, pp 134–1431Google Scholar
- Bannister GC, Wallace WA, Stableforth PG, Hutson MA (1989) The management of acute acromioclavicular dislocation. A randomised prospective controlled trial. J Bone Joint Surg Br 71:848–850PubMedGoogle Scholar
- Phillips AM, Smart C, Groom AFG (1998) Acromioclavicular dislocation. Conservative or surgical therapy. Clin Orthop Relat Res 353:10–17PubMedView ArticleGoogle Scholar
- Geaney LE, Miller LD, Ticker JB, Romeo AA, Guerra JJ, Arciero RA, De Berardino TM, Mazzocca A (2010) Management of the failed AC joint reconstruction: causation and treatment. Sport Med Arthrosc 18:167–172Google Scholar
- Fleming RE, Tornberg DN, Kiernen H (1978) An operative repair of acromioclavicular separation. J Trauma 18:709–712PubMedView ArticleGoogle Scholar
- Nicholas SJ, Lee SJ, Mullaney MJ et al (2007) Clinical outcomes of coracoclavicular ligament reconstructions using tendon grafts. Am J Sports Med 35:1912–1917Google Scholar
- Constant CR, Murley AH (1987) A clinical method of functional assesment of the shoulder. Clin Orthop 214:150–154Google Scholar
- Galatz LM, Williams GR Jr (2001) Acromioclavicular joint injuries. In: Bucholz RW, Heckman JD (eds) Rockwood and Green’s fractures in adults. Lippincott Williams & Wilkins, Philadelphia, pp 1209–1244Google Scholar
- Rosenorm M, Pedersen E (1974) A comparison between conservative and operative treatment of acute acromioclavicular dislocation. Acta Orthop Scand 45:50–59View ArticleGoogle Scholar
- Copeland S (1995) Operative shoulder surgery. Churchill Livingstone, New YorkGoogle Scholar
- Cooper ES (1861) New method of treating long standing dislocations of the scapula–clavicle articulation. Am J Med Sci 1:389–392Google Scholar
- Weaver JK, Dunn HK (1972) Treatment of acromioclavicular incurie especially complete acromioclavicular separation. J Bone Joint Surg Am 54:1187–1194PubMedGoogle Scholar
- Mazzocca AD, Carofino BC (2010) The anatomic coracoclavicular ligament reconstruction: surgical technique and indications. J Should Elb Surg 19:37–46View ArticleGoogle Scholar
- Costic RS, Labriola JE, Rodosky MW, Debski RE (2004) Biomechanical rationale for development of anatomical reconstructions of coracoclavicular ligaments after complete acromioclavicular joint dislocations. Am J Sports Med 32:1929–1936Google Scholar
- Gonzalez R, Damacen H, Nyland J et al (2007) Acromioclavicular joint reconstruction using peroneus brevis tendon allograft. Arthroscopy 23(7):788.e1–788.e4View ArticleGoogle Scholar
- Jones HP, Lemos MJ, Schepsis AA (2001) Salvage of failed acromioclavicular joint reconstruction using autogenous semitendinosus tendon from the knee. Surgical technique and case report. Am J Sports Med 29:234–237Google Scholar
- Bosworth BM (1948) Acromioclavicular dislocation: end-results of screw suspension treatment. Ann Surg 127:98–111PubMed CentralPubMedView ArticleGoogle Scholar
- Morrison DS, Lemos MJ (1995) Acromioclavicular separation: reconstruction using synthetic loop augmentation. Am J Sports Med 23:105–110PubMedView ArticleGoogle Scholar
- Fialka C, Hexel M, Stampfl P, Oberleitner G, Vecsei V (2004) Traumatic acromioclavicular joint separations. Current concepts. Eur surg 36:20–24View ArticleGoogle Scholar
- Goldberg JA, Viglione W, Cumming WJ et al (1987) Review of coracoclavicular ligament reconstruction using Dacron graft material. Aust N Z J Surg 57:441–445PubMedView ArticleGoogle Scholar
- Nau T, Lavoie P, Duval N (2002) A new generation of artificial ligaments in reconstruction of the anterior cruciate ligament. Two-year follow-up of a randomised trial. J Bone Joint Surg Br 84(3):356–360PubMedView ArticleGoogle Scholar
- Bailey R, O’Connor G, Titus P et al (1972) A dynamic repair for acute and chronic injuries of the acromioclavicular area. J Bone Joint Surg Am 54:180235Google Scholar
- Dewar FP, Barrington TW (1965) The treatment of chronic acromioclavicular dislocation. J Bone Joint Surg Br 47:32–35Google Scholar
- Sloan SM, Budoff JE, Hipp JA, Nguyen L (2004) Coracoclavicular ligament reconstruction using the lateral half of the conjoined tendon. J Should Elb Surg 13:186–190View ArticleGoogle Scholar
- Milka S, Wojcik B, Nowak R (1994) Early results of coracoclavicular ligament reconstruction with carbon fiber prosthesis in patients with acromioclavicular dislocation. Chir Narzadow Ruchu Ortop Pol 59:491–496PubMedGoogle Scholar
- Muller Mai CM, Gross UM (1991) Histological and ultrastructural observations at the interface of expanded polytetrafluorethylene anterior cruciate ligament implants. J Appl Biomater Spring 2(1):29–35View ArticleGoogle Scholar
- Olson EJ, Kang J, Fu F, Georgescu H, Mason G, Evans C (1988) The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies. Am J Sports Med 16:558–570PubMedView ArticleGoogle Scholar
- Lee SJ, Nicholas SJ, Akizuki KH, McHugh MP, Kremenic IJ, Ben-Avi S (2003) Reconstruction of the coracoclavicular ligaments with tendon grafts: a comparative biomechanical study. Am J Sports Med 31:648–655PubMedGoogle Scholar
- Calvo E, Lopez-Franco M, Arribas IM (2006) Clinical and radiologic outcomes of surgical and conservative treatment of type III acromioclavicular joint injury. J Should Elb Surg 15:300–305View ArticleGoogle Scholar
- Mouhsine E, Garofalo E, Crevoisier X, Farron A (2003) Grade I and II acromioclavicular dislocations: results of conservative treatment. J Should Elb Surg 12:599–602View ArticleGoogle Scholar
- Yoo JC, Choi NH, Kim SY, Lim TK (2006) Distal clavicle tunnel widening after coracoclavicular ligament reconstruction with semitendinous tendon: a case report. J Should Elb Surg 15(2):256–259View ArticleGoogle Scholar
- Nebelung W, Becker R, Merkel M, Ropke M (1998) Bone tunnel enlargement after anterior cruciate ligament reconstruction with semitendinosus tendon using endobutton fixation on the femoral side. Arthroscopy 14:810–815PubMedView ArticleGoogle Scholar
- Greiner S, Braunsdorf J, Perka C, Herrmann S, Scheffler S (2009) Mid to long-term results of open acromioclavicular-joint reconstruction using polydioxansulfate cerclage augmentation. Arch Orthop Trauma Surg 129:735–740PubMedView ArticleGoogle Scholar