- Email: [email protected]
Primary Fixation of Acromioclavicular Joint Disruption
Primary Fixation of Acromioclavicular Joint Disruption$ Sepp Braun, MD, Andreas B. Imhoff, MD, and Frank Martetschlaeger, MD Acromioclavicular (AC) joint separations are frequently seen injuries and may lead to severe impairment of shoulder function. Numerous treatment options have been proposed in the literature. Although low-grade injuries (types I and II) should be initially managed nonsurgically, surgical management is typically recommended for high-grade lesions (types IV through VI). Surgery is suggested for type III lesions in heavy laborers or high-level athletes. Owing to the relatively high complication rates of modern anatomical double-tunnel AC reconstruction techniques, the authors present a preferred single-tunnel technique with additional AC joint suture cord cerclage for improved horizontal stability. This technique allows the combination of small drill hole diameter with ultra-high-strength suture tape material and large cortical fixation buttons. Oper Tech Sports Med ]:]]]-]]] C 2014 Published by Elsevier Inc.
KEYWORDS acromioclavicular instability, AC joint, AC joint reconstruction
Introduction
A
pproximately 12% of all acute shoulder injuries affect the acromioclavicular (AC) joint. Particularly in young and active men, even higher incidences can be found.1 Participation in high-impact sports, such as soccer, American football, rugby, also skiing, snowboarding, and road or mountain biking frequently leads to this injury of the shoulder girdle owing to a direct blow to the shoulder with the arm adducted. Appreciation of the anatomical structures that provide the AC joints stability is vital for successful and sustainable treatment. There are 2 ligamentous main structures that stabilize the AC joint in vertical and horizontal directions. The coracoclavicular (CC) ligaments primarily prevent the lateral clavicle from dislocating superiorly, whereas the AC ligaments mainly contribute to horizontal stability of the AC joint. The native joint allows motion of the lateral clavicle of up to 4-6 mm superiorly and rotation with moving up the arm of
Department for Orthopaedic Sportsmedicine, Technical University of Munich, Munich, Germany. ☆ Conflict of Interest: All authors (S.B., A.B.I., and F.M.) receive financial and material research support from Arthrex Inc, Karlsfeld, Germany; A.B.I. S.B. are consultants to Arthrex Inc, Karlsfeld, Germany. Address reprint requests to Sepp Braun, Abt. für Sportorthopädie, Technische Universität München, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 München, Germany. E-mail: [email protected]
http://dx.doi.org/10.1053/j.otsm.2014.03.005 1060-1872/& 2014 Published by Elsevier Inc.
up to almost 101.2 The anteromedially located conoid and the posterolateral trapezoid ligament build the CC ligament complex, spanning from the clavicle to the knuckle of the coracoid process. Anatomical and biomechanical studies showed that the conoid ligament is the primary restraint to superior displacement and rotation of the clavicle.2,3 The superior and posterior portions of the AC ligaments mainly stabilize posterior translation.3 Reconstruction for separations of the AC joint should restore both superior and horizontal stability for favorable outcomes.
Classification The Rockwood classification of AC joint separations is internationally used and widely accepted. It is based on the acknowledgment of the anatomical structures, the injury mechanisms and clinical observations. Type VI injuries are typically not seen in clinical routine (Fig. 1). The classification considers exclusively x-ray studies for grading the injury in types I-VI. However, there is a lively discussion on how to accurately distinguish Rockwood type III from type IV injuries. For this reason, most surgeons presently include clinical examination and dynamic instability of the distal clavicle and special x-ray imaging in their decisionmaking algorithm. 1
S. Braun et al.
2
Diagnosis Clinical Examination and Symptoms In almost all cases, the patient complains about acute shoulder pain with a history of trauma. This trauma typically is described as a direct blow to the lateral aspect of the shoulder. The pain usually is indicated right at the AC joint, and sometimes it is reported to radiate to the neck.4,5 Inspection of the acutely injured shoulder girdle frequently unveils skin abrasions and a visible prominence of the distal clavicle that results from inferior displacement of the scapula. Tenderness to palpation is found in the acute setting. The direction of instability can be evaluated clinically with attention to posterior displacement and if the AC joint is reducible. Pain frequently limits range of motion.6-9 Anterior-superior shoulder pain may be localized with clinical tests for the AC joint pathology (eg, O’Brien and cross-body), which are particularly helpful for detecting low-grade injuries (types I and II) without palpable deformity.1,5 High-grade AC separations (types III-VI) frequently occur with concomitant intra-articular injuries. Therefore, a thorough examination and review of magnetic resonance imaging scans is needed.8 In carefully selected cases, an AC joint injection with lidocaine may be helpful in discriminating AC joint pain from other pathologies causing anterior or superior shoulder pain.
Imaging
Figure 1 Rockwood’s classification of AC joint separations based on radiographic findings.
Standard imaging series for accurate diagnosis of acute AC injuries include plain x-ray, with anterorposterior (AP) view, Y view, axial view, and Alexander or Zanca studies (Fig. 2). The AP view allows the surgeon to identify vertical displacement of the distal clavicle, whereas the Alexander view clearly visualizes displacement in posterior direction as the arm is put in flexion
Figure 2 Radiographic studies of an acute AC joint injury. From left to right, the images show a true AP and Y view without significant dislocation of the distal clavicle. The axial view shows a minimal posterior displacement of the clavicle (marked with red lines). In the very right image, the Alexander view visualizes the posterior instability of the distal clavicle as the arm is adducted. (Color version of figure is available online.)
Primary fixation of AC joint disruption and full adduction. The Zanca view, an AP view that is tilted 101-151 cephalad, can give a clear view of the AC joint without superimposing structures.10 Bearden et al11 showed that a 25%-50% increase of the CC distance means a complete CC ligament disruption. Consequently, measurement of the CC interval of the index and the contralateral shoulder compared can be useful in cases of uncertain degree of severity. Weighted stress radiographs have been used to discriminate type II from occult type III injuries12,13; however, it has been shown that these radiographs do not improve the diagnostic accuracy and thus cause avoidable patient discomfort.14,15
Treatment Options Nonoperative treatment is suggested, with a wide consensus for AC joint injuries Rockwood types I and II, which have shown satisfactory results in a number of studies.16-20 Usually a simple arm sling is used for immobilizing the shoulder for 1-3 weeks. This is followed by early range-of-motion exercises. As some studies have reported persistent symptoms after nonoperative treatment of low-grade injuries,16,17,21,22 early distal clavicle excision may be an option for carefully selected patients with Rockwood type II injuries.23 This can, in some settings, create chronic and painful AC instability and thus is not recommended by the authors. However, to date there is no clear evidence recommending early surgical treatment for types I and II injuries. Treatment of acute type III AC injuries is still a highly controversial discussion. As most clinical studies have not shown significant advantages for early surgical treatment, a trial of conservative treatment is typically recommended.24-27 Based on the findings of a few clinical studies, some authors believe that early surgery for type III injuries results in better clinical outcomes compared with patients undergoing surgery later than 3 months after the injury with unsuccessful initial nonoperative treatment.28,29 Thus, early surgical repair of type III AC lesions should particularly be considered in manual workers or overhead athletes.24,25,29 Types IV and V (and VI) lesions are typically treated with surgery to avoid the reported long-term natural history of chronic pain and loss of function.17,24,25,29-31 Possible contraindications or limitations for the presented surgical interventions besides all common contraindications for surgery include concomitant acute fractures of the coracoid process or the distal clavicle, that need to be addressed (eg, hooked plate).
Authors’ Preferred Surgical Technique for Acute AC Joint Fixation The patient is in a beach-chair position under general anesthesia. The patient’s head should be slightly turned and tilted toward the contralateral shoulder as this allows a better angle for drilling of the transclavicular and transcoracoidal tunnel. Correct access for intraoperative imaging with the
3 C-arm should be tested before the shoulder is prepared and draped in standard fashion. Use of a mechanical arm holder is strongly recommended for this surgery, as it significantly helps to position the arm and to reduce the AC joint. Anatomical landmarks are identified and marked on the skin. Surgery starts with a diagnostic arthroscopy using the standard posterior viewing portal. Concomitant intra-articular injuries should be addressed as needed. A deep anterolateral portal is established in an outside-in technique through the rotator interval and parallel to the subscapularis tendon under direct visualization. This portal is secured with a flexible silicone cannula, and the base and arch of the coracoid is skeletonized with an electrothermal ablation device. For optimal view of the base of the coracoid, the arthroscope is switched to an additional transsupraspinatus viewing portal right posterior to the long head of the biceps tendon. A 30-mm skin incision is established over the AC joint in line and central with the distal clavicle. The AC joint is exposed. The joint capsule is carefully mobilized elevating the anterior and posterior flaps subperiosteally as a single layer, which facilitates its later repair. Possible soft tissue interpositions preventing proper reduction (eg, torn articular disc) are sharply removed. Next, a 2.4-mm drill wire with eyelet is used to drill a hole into the lateral clavicle, approximately 10-15 mm medial and parallel to the AC joint line in posterior-to-anterior direction. This step can be performed easily, with the AC joint being still unreduced leaving the lateral clavicle mobile. By use of the eyelet of the drill wire, a shuttle suture is passed through the distal clavicle. Using an AC joint drill guide, a corresponding drill hole is then placed into the acromion, approximately 10 mm lateral to the joint line, starting from the anterior edge to the acromion surface at the posterior border of the AC joint. The eyelet of the wire is again used to pass a second shuttle suture. With these sutures, a 1.5-mm polydioxanone (PDS) cord is then passed through the drill holes in a figure-of-eight configuration. Tying of the AC PDS cord is performed at the end of the procedure. This cerclage will particularly improve horizontal stability.32 Next, reduction of the AC joint is performed by lifting the extremity with the pneumatic arm holder. In cases where maintenance of reduction is difficult, a K-wire can be used for temporary transfixation of the AC joint. For restoration of vertical stability a coracoclavicular reconstruction is performed with a suture—cortical fixation button device. A second 30-mm skin incision is made within Langer lines in line with the clavicle approximately 35 mm medial to the AC joint line. This point has been described to represent the correct location between the native insertions of the trapezoid and conoid ligaments.33,34 Subsequently, the trapezoid fascia is exposed and incised in line with the fibers of the trapezoid muscle, and the clavicle can be exposed with its anterior and posterior cortical margins. For coracoclavicular tunnel placement, the AC joint drill guide is inserted through the anterolateral portal. A 2.4-mm cannulated drill is then used to drill the coracoclavicular tunnel approximately 35 mm medial to the AC joint transclavicular and close to the base of the coracoid process. Owing to the oblique drilling direction, the entrance point of the calvicular
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4
Figure 3 The position of the drill is verified under fluoroscopy with a probe (center image) to mark the anteromedial (left image) and posterolateral (right image) margins of the base of the coracoid. (Color version of figure is available online.)
drill hole should be placed slightly posterior to the midline. The correct positioning of the tunnel is verified under fluoroscopy with a probe (Fig. 3). Subsequently a SutureLasso wire loop is inserted through the cannulated drill bit, before it is removed. By use of this shuttle wire, the free strands of 2 high-strength suture tapes (eg, FiberTape; Arthrex, Naples, FL) are shuttled upward through the coracoid and the clavicle. The loops are threaded in a special titanium button (DogBone; Arthrex, Naples, FL), and the button is placed under the coracoid process using a grasper through the anteroinferior portal. Correct placement of the button under the coracoid is controlled by direct visualization (Fig. 4). The reduction of the AC joint is again verified under fluoroscopy before the 4 free
Figure 4 The button with suture tapes as it is finally placed underneath the base of the coracoid. Arthroscopic view from the lateral transsupraspinatus portal. (n) Marks the base of the coracoid, the arrow pointing toward the tip of the coracoid. (Color version of figure is available online.)
strands of the suture tapes are threaded in a second titanium button on top of the clavicle. Next, the suture tapes are tightened and secured by alternating knots. Finally, the capsule of the AC joint is meticulously reconstructed using absorbable sutures, and the AC PDS cerclage is secured by alternating knots, ideally posterior to the AC joint to avoid irritation by the knot (Fig. 5). The layers and skin are closed in a standard manner. Figure 6 shows a standard postoperative x-ray control to confirm correct reduction and implant position.
Postoperative Treatment To minimize strain on the reconstructed CC ligaments, the shoulder is immobilized in a sling for 6 weeks postoperatively.
Figure 5 The drawing shows the PDS cerclage in a figure of eight for direct AC joint stabilization. The dotted lines mark the horizontal drill holes through the lateral clavicle (drilled from posterior to anterior) and the acromion (drilled from anterior to posterior aiming cranially). (Color version of figure is available online.)
Primary fixation of AC joint disruption
5 grade injuries (types I and II) should be initially managed nonsurgically, surgical management is typically recommended for high-grade lesions (types IV through VI) and in some type III lesions in heavy laborers or high-level athletes. Owing to the relatively high complication rates of modern AC reconstruction techniques, the authors currently prefer the described technique, using a single, small coracoclavicular drill hole. Although our early results are encouraging, investigation with long-term follow-up will be necessary to show the value and possible advantages of the procedure.
References Figure 6 The postoperative x-ray control confirms correct positioning of the implants and drill holes and the anatomical reduction of the AC joint.
Within the first 2 weeks, passive motion exercises are performed limited to 301 of flexion and abduction as well as to 801 internal rotation and 01 external rotation. At 3-4weeks, range-of-motion exercises are performed up to 451 flexion and abduction in an active-assisted manner. After 5-6 weeks, rangeof-motion exercises are advanced to 601 of flexion and abduction with an unlimited rotation. Active motion in the upright position is then advanced per the patient’s tolerance. After regaining pain-free full-active range of motion, strengthening exercises can start around the 12th postoperative week. Unrestricted return to work is usually allowed at 12-16 weeks after surgery. Patients are typically allowed to go back to fullcontact athletics after 5-6 months.35
Clinical Results Clinical results of modern anatomical arthroscopically assisted techniques for AC joint reconstruction with 2 drill tunnels have been favorable in midterm and long-term follow-ups.36,37 Nonetheless, these surgical techniques are highly demanding and dependent on the skills of the surgeon. In some cases, the anatomy of the patient may even exclude correct and safe positioning of the bone tunnels.38 It has been shown in the literature that only one bone tunnel for CC reconstruction can provide comparable clinical results.39 Primary stability of single-tunnel techniques (without additional AC joint cerclage) showed similar strength to the native ligaments in biomechanical testing but cannot yet reach the load-to-failure strength of double-tunnel techniques. To improve this stability, the authors recommended adding the AC joint cerclage with a PDS cord, which particularly reduces horizontal stability of the distal clavicle.32
Conclusion AC joint separations are common injuries and may lead to severe impairment of shoulder function. Numerous treatment options have been proposed in the literature. Although low-
1. Fraser-Moodie JA, Shortt NL, Robinson CM: Injuries to the acromioclavicular joint. J Bone Joint Surg Br 90(6):697-707, 2008 2. Debski RE, Parsons 3rd IM, Fenwick J, et al: Ligament mechanics during three degree-of-freedom motion at the acromioclavicular joint. Ann Biomed Eng 28(6):612-618, 2000 3. Fukuda K, Craig EV, An KN, et al: Biomechanical study of the ligamentous system of the acromioclavicular joint. J Bone Joint Surg Am 68(3):434-440, 1986 4. Iannotti JP, Williams GR: Disorders of the Shoulder: Diagnosis and Management. . Philadelphia: Lippincott Williams & Wilkins, 1999 5. Mazzocca AD, Arciero RA, Bicos J: Evaluation and treatment of acromioclavicular joint injuries. Am J Sports Med 35(2):316-329, 2007 6. Ebraheim NA, An HS, Jackson WT, et al: Scapulothoracic dissociation. J Bone Joint Surg Am 70(3):428-432, 1988 7. Egol KA, Connor PM, Karunakar MA, et al: The floating shoulder: Clinical and functional results. J Bone Joint Surg Am 83-A(8):1188-1194, 2001 8. Tischer T, Salzmann GM, El-Azab H, et al: Incidence of associated injuries with acute acromioclavicular joint dislocations types III through V. Am J Sports Med 37(1):136-139, 2009 9. Wilson KM, Colwill JC: Combined acromioclavicular dislocation with coracoclavicular ligament disruption and coracoid process fracture. Am J Sports Med 17(5):697-698, 1989 10. Zanca P: Shoulder pain: Involvement of the acromioclavicular joint. (Analysis of 1,000 cases). Am J Roentgenol Radium Ther Nucl Med 112 (3):493-506, 1971 11. Bearden JM, Hughston JC, Whatley GS: Acromioclavicular dislocation: Method of treatment. J Sports Med 1(4):5-17, 1973 12. Gstettner C, Tauber M, Hitzl W, et al: Rockwood type III acromioclavicular dislocation: Surgical versus conservative treatment. JShoulder Elbow Surg 17(2):220-225, 2008 13. Imatani RJ, Hanlon JJ, Cady GW: Acute, complete acromioclavicular separation. J Bone Joint Surg Am 57(3):328-332, 1975 14. Yoo JC, Ahn JH, Yoon JR, et al: Clinical results of single-tunnel coracoclavicular ligament reconstruction using autogenous semitendinosus tendon. Am J Sports Med 38(5):950-957, 2010 15. Bossart PJ, Joyce SM, Manaster BJ, et al: Lack of efficacy of “weighted” radiographs in diagnosing acute acromioclavicular separation. Ann Emerg Med 17(1):20-24, 1988 16. Bergfeld JA, Andrish JT, Clancy WG: Evaluation of the acromioclavicular joint following first- and second-degree sprains. Am J Sports Med 6 (4):153-159, 1978 17. Cox JS: The fate of the acromioclavicular joint in athletic injuries. Am J Sports Med 9(1):50-53, 1981 18. Dias JJ, Steingold RF, Richardson RA, et al: The conservative treatment of acromioclavicular dislocation. Review after five years. J Bone Joint Surg Br 69(5):719-722, 1987 19. Glick JM, Milburn LJ, Haggerty JF, et al: Dislocated acromioclavicular joint: Follow-up study of 35 unreduced acromioclavicular dislocations. Am J Sports Med 5(6):264-270, 1977 20. Lemos MJ: The evaluation and treatment of the injured acromioclavicular joint in athletes. Am J Sports Med 26(1):137-144, 1998 21. Mikek M: Long-term shoulder function after type I and II acromioclavicular joint disruption. Am J Sports Med 36(11):2147-2150, 2008
6 22. Mouhsine E, Garofalo R, Crevoisier X, et al: Grade I and II acromioclavicular dislocations: Results of conservative treatment. J Shoulder Elbow Surg 12(6):599-602, 2003 23. Song HS, Song SY, Yoo YS, et al: Symptomatic residual instability with grade II acromioclavicular injury. J Orthop Sci 2012 24. Bannister GC, Wallace WA, Stableforth PG, et al: The management of acute acromioclavicular dislocation. A randomised prospective controlled trial. J Bone Joint Surg Br 71(5):848-850, 1989 25. Larsen E, Bjerg-Nielsen A, Christensen P: Conservative or surgical treatment of acromioclavicular dislocation. A prospective, controlled, randomized study. J Bone Joint Surg Am 68(4):552-555, 1986 26. Spencer Jr. EE: Treatment of grade III acromioclavicular joint injuries: A systematic review. Clin Orthop Relat Res 455:38-44, 2007 27. Tibone J, Sellers R, Tonino P: Strength testing after third-degree acromioclavicular dislocations. Am J Sports Med 20(3):328-331, 1992 28. Rolf O, Hann von Weyhern A, Ewers A, et al: Acromioclavicular dislocation Rockwood III-V: Results of early versus delayed surgical treatment. Arch Orthop Trauma Surg 128(10):1153-1157, 2008 29. Weinstein DM, McCann PD, McIlveen SJ, et al: Surgical treatment of complete acromioclavicular dislocations. Am J Sports Med 23 (3):324-331, 1995 30. Millett PJ, Braun S, Gobezie R, et al: Acromioclavicular joint reconstruction with coracoacromial ligament transfer using the docking technique. BMC Musculoskelet Disord 10:6, 2009 31. Martetschlager F, Horan MP, Warth RJ, et al: Complications after anatomic fixation and reconstruction of the coracoclavicular ligaments. Am J Sports Med 14(12):2896-2903, 2013
S. Braun et al. 32. Saier T, Venjakob AJ, Minzlaff P, et al: Value of additional acromioclavicular cerclage for horizontal stability in complete acromioclavicular separation: A biomechanical study. Knee Surg Sports Traumatol Arthrosc 2014 33. Rios CG, Arciero RA, Mazzocca AD: Anatomy of the clavicle and coracoid process for reconstruction of the coracoclavicular ligaments. Am J Sports Med 35(5):811-817, 2007 34. Salzmann GM, Paul J, Sandmann GH, et al: The coracoidal insertion of the coracoclavicular ligaments: An anatomic study. Am J Sports Med 36 (12):2392-2397, 2008 35. Warth RJ, Martetschlager F, Gaskill TR, et al: Acromioclavicular joint separations. Curr Rev Musculoskelet Med 6(1):71-78, 2013 36. Salzmann GM, Walz L, Buchmann S, et al: Arthroscopically assisted 2bundle anatomical reduction of acute acromioclavicular joint separations. Am J Sports Med 38(6):1179-1187, 2010 37. Venjakob AJ, Salzmann GM, Gabel F, et al: Arthroscopically assisted 2-bundle anatomic reduction of acute acromioclavicular joint separations: 58-Month findings. Am J Sports Med 41 (3):615-621, 2013 38. Coale RM, Hollister SJ, Dines JS, et al: Anatomic considerations of transclavicular-transcoracoid drilling for coracoclavicular ligament reconstruction. J Shoulder Elbow Surg 22(1):137-144, 2013 39. Patzer T, Clauss C, Kuhne CA, et al: Arthroscopically assisted reduction of acute acromioclavicular joint separations: Comparison of clinical and radiological results of single versus double TightRope technique. Unfallchirurg 116(5):442-450, 2013
KEYWORDS acromioclavicular instability, AC joint, AC joint reconstruction
Introduction
A
pproximately 12% of all acute shoulder injuries affect the acromioclavicular (AC) joint. Particularly in young and active men, even higher incidences can be found.1 Participation in high-impact sports, such as soccer, American football, rugby, also skiing, snowboarding, and road or mountain biking frequently leads to this injury of the shoulder girdle owing to a direct blow to the shoulder with the arm adducted. Appreciation of the anatomical structures that provide the AC joints stability is vital for successful and sustainable treatment. There are 2 ligamentous main structures that stabilize the AC joint in vertical and horizontal directions. The coracoclavicular (CC) ligaments primarily prevent the lateral clavicle from dislocating superiorly, whereas the AC ligaments mainly contribute to horizontal stability of the AC joint. The native joint allows motion of the lateral clavicle of up to 4-6 mm superiorly and rotation with moving up the arm of
Department for Orthopaedic Sportsmedicine, Technical University of Munich, Munich, Germany. ☆ Conflict of Interest: All authors (S.B., A.B.I., and F.M.) receive financial and material research support from Arthrex Inc, Karlsfeld, Germany; A.B.I. S.B. are consultants to Arthrex Inc, Karlsfeld, Germany. Address reprint requests to Sepp Braun, Abt. für Sportorthopädie, Technische Universität München, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 München, Germany. E-mail: [email protected]
http://dx.doi.org/10.1053/j.otsm.2014.03.005 1060-1872/& 2014 Published by Elsevier Inc.
up to almost 101.2 The anteromedially located conoid and the posterolateral trapezoid ligament build the CC ligament complex, spanning from the clavicle to the knuckle of the coracoid process. Anatomical and biomechanical studies showed that the conoid ligament is the primary restraint to superior displacement and rotation of the clavicle.2,3 The superior and posterior portions of the AC ligaments mainly stabilize posterior translation.3 Reconstruction for separations of the AC joint should restore both superior and horizontal stability for favorable outcomes.
Classification The Rockwood classification of AC joint separations is internationally used and widely accepted. It is based on the acknowledgment of the anatomical structures, the injury mechanisms and clinical observations. Type VI injuries are typically not seen in clinical routine (Fig. 1). The classification considers exclusively x-ray studies for grading the injury in types I-VI. However, there is a lively discussion on how to accurately distinguish Rockwood type III from type IV injuries. For this reason, most surgeons presently include clinical examination and dynamic instability of the distal clavicle and special x-ray imaging in their decisionmaking algorithm. 1
S. Braun et al.
2
Diagnosis Clinical Examination and Symptoms In almost all cases, the patient complains about acute shoulder pain with a history of trauma. This trauma typically is described as a direct blow to the lateral aspect of the shoulder. The pain usually is indicated right at the AC joint, and sometimes it is reported to radiate to the neck.4,5 Inspection of the acutely injured shoulder girdle frequently unveils skin abrasions and a visible prominence of the distal clavicle that results from inferior displacement of the scapula. Tenderness to palpation is found in the acute setting. The direction of instability can be evaluated clinically with attention to posterior displacement and if the AC joint is reducible. Pain frequently limits range of motion.6-9 Anterior-superior shoulder pain may be localized with clinical tests for the AC joint pathology (eg, O’Brien and cross-body), which are particularly helpful for detecting low-grade injuries (types I and II) without palpable deformity.1,5 High-grade AC separations (types III-VI) frequently occur with concomitant intra-articular injuries. Therefore, a thorough examination and review of magnetic resonance imaging scans is needed.8 In carefully selected cases, an AC joint injection with lidocaine may be helpful in discriminating AC joint pain from other pathologies causing anterior or superior shoulder pain.
Imaging
Figure 1 Rockwood’s classification of AC joint separations based on radiographic findings.
Standard imaging series for accurate diagnosis of acute AC injuries include plain x-ray, with anterorposterior (AP) view, Y view, axial view, and Alexander or Zanca studies (Fig. 2). The AP view allows the surgeon to identify vertical displacement of the distal clavicle, whereas the Alexander view clearly visualizes displacement in posterior direction as the arm is put in flexion
Figure 2 Radiographic studies of an acute AC joint injury. From left to right, the images show a true AP and Y view without significant dislocation of the distal clavicle. The axial view shows a minimal posterior displacement of the clavicle (marked with red lines). In the very right image, the Alexander view visualizes the posterior instability of the distal clavicle as the arm is adducted. (Color version of figure is available online.)
Primary fixation of AC joint disruption and full adduction. The Zanca view, an AP view that is tilted 101-151 cephalad, can give a clear view of the AC joint without superimposing structures.10 Bearden et al11 showed that a 25%-50% increase of the CC distance means a complete CC ligament disruption. Consequently, measurement of the CC interval of the index and the contralateral shoulder compared can be useful in cases of uncertain degree of severity. Weighted stress radiographs have been used to discriminate type II from occult type III injuries12,13; however, it has been shown that these radiographs do not improve the diagnostic accuracy and thus cause avoidable patient discomfort.14,15
Treatment Options Nonoperative treatment is suggested, with a wide consensus for AC joint injuries Rockwood types I and II, which have shown satisfactory results in a number of studies.16-20 Usually a simple arm sling is used for immobilizing the shoulder for 1-3 weeks. This is followed by early range-of-motion exercises. As some studies have reported persistent symptoms after nonoperative treatment of low-grade injuries,16,17,21,22 early distal clavicle excision may be an option for carefully selected patients with Rockwood type II injuries.23 This can, in some settings, create chronic and painful AC instability and thus is not recommended by the authors. However, to date there is no clear evidence recommending early surgical treatment for types I and II injuries. Treatment of acute type III AC injuries is still a highly controversial discussion. As most clinical studies have not shown significant advantages for early surgical treatment, a trial of conservative treatment is typically recommended.24-27 Based on the findings of a few clinical studies, some authors believe that early surgery for type III injuries results in better clinical outcomes compared with patients undergoing surgery later than 3 months after the injury with unsuccessful initial nonoperative treatment.28,29 Thus, early surgical repair of type III AC lesions should particularly be considered in manual workers or overhead athletes.24,25,29 Types IV and V (and VI) lesions are typically treated with surgery to avoid the reported long-term natural history of chronic pain and loss of function.17,24,25,29-31 Possible contraindications or limitations for the presented surgical interventions besides all common contraindications for surgery include concomitant acute fractures of the coracoid process or the distal clavicle, that need to be addressed (eg, hooked plate).
Authors’ Preferred Surgical Technique for Acute AC Joint Fixation The patient is in a beach-chair position under general anesthesia. The patient’s head should be slightly turned and tilted toward the contralateral shoulder as this allows a better angle for drilling of the transclavicular and transcoracoidal tunnel. Correct access for intraoperative imaging with the
3 C-arm should be tested before the shoulder is prepared and draped in standard fashion. Use of a mechanical arm holder is strongly recommended for this surgery, as it significantly helps to position the arm and to reduce the AC joint. Anatomical landmarks are identified and marked on the skin. Surgery starts with a diagnostic arthroscopy using the standard posterior viewing portal. Concomitant intra-articular injuries should be addressed as needed. A deep anterolateral portal is established in an outside-in technique through the rotator interval and parallel to the subscapularis tendon under direct visualization. This portal is secured with a flexible silicone cannula, and the base and arch of the coracoid is skeletonized with an electrothermal ablation device. For optimal view of the base of the coracoid, the arthroscope is switched to an additional transsupraspinatus viewing portal right posterior to the long head of the biceps tendon. A 30-mm skin incision is established over the AC joint in line and central with the distal clavicle. The AC joint is exposed. The joint capsule is carefully mobilized elevating the anterior and posterior flaps subperiosteally as a single layer, which facilitates its later repair. Possible soft tissue interpositions preventing proper reduction (eg, torn articular disc) are sharply removed. Next, a 2.4-mm drill wire with eyelet is used to drill a hole into the lateral clavicle, approximately 10-15 mm medial and parallel to the AC joint line in posterior-to-anterior direction. This step can be performed easily, with the AC joint being still unreduced leaving the lateral clavicle mobile. By use of the eyelet of the drill wire, a shuttle suture is passed through the distal clavicle. Using an AC joint drill guide, a corresponding drill hole is then placed into the acromion, approximately 10 mm lateral to the joint line, starting from the anterior edge to the acromion surface at the posterior border of the AC joint. The eyelet of the wire is again used to pass a second shuttle suture. With these sutures, a 1.5-mm polydioxanone (PDS) cord is then passed through the drill holes in a figure-of-eight configuration. Tying of the AC PDS cord is performed at the end of the procedure. This cerclage will particularly improve horizontal stability.32 Next, reduction of the AC joint is performed by lifting the extremity with the pneumatic arm holder. In cases where maintenance of reduction is difficult, a K-wire can be used for temporary transfixation of the AC joint. For restoration of vertical stability a coracoclavicular reconstruction is performed with a suture—cortical fixation button device. A second 30-mm skin incision is made within Langer lines in line with the clavicle approximately 35 mm medial to the AC joint line. This point has been described to represent the correct location between the native insertions of the trapezoid and conoid ligaments.33,34 Subsequently, the trapezoid fascia is exposed and incised in line with the fibers of the trapezoid muscle, and the clavicle can be exposed with its anterior and posterior cortical margins. For coracoclavicular tunnel placement, the AC joint drill guide is inserted through the anterolateral portal. A 2.4-mm cannulated drill is then used to drill the coracoclavicular tunnel approximately 35 mm medial to the AC joint transclavicular and close to the base of the coracoid process. Owing to the oblique drilling direction, the entrance point of the calvicular
S. Braun et al.
4
Figure 3 The position of the drill is verified under fluoroscopy with a probe (center image) to mark the anteromedial (left image) and posterolateral (right image) margins of the base of the coracoid. (Color version of figure is available online.)
drill hole should be placed slightly posterior to the midline. The correct positioning of the tunnel is verified under fluoroscopy with a probe (Fig. 3). Subsequently a SutureLasso wire loop is inserted through the cannulated drill bit, before it is removed. By use of this shuttle wire, the free strands of 2 high-strength suture tapes (eg, FiberTape; Arthrex, Naples, FL) are shuttled upward through the coracoid and the clavicle. The loops are threaded in a special titanium button (DogBone; Arthrex, Naples, FL), and the button is placed under the coracoid process using a grasper through the anteroinferior portal. Correct placement of the button under the coracoid is controlled by direct visualization (Fig. 4). The reduction of the AC joint is again verified under fluoroscopy before the 4 free
Figure 4 The button with suture tapes as it is finally placed underneath the base of the coracoid. Arthroscopic view from the lateral transsupraspinatus portal. (n) Marks the base of the coracoid, the arrow pointing toward the tip of the coracoid. (Color version of figure is available online.)
strands of the suture tapes are threaded in a second titanium button on top of the clavicle. Next, the suture tapes are tightened and secured by alternating knots. Finally, the capsule of the AC joint is meticulously reconstructed using absorbable sutures, and the AC PDS cerclage is secured by alternating knots, ideally posterior to the AC joint to avoid irritation by the knot (Fig. 5). The layers and skin are closed in a standard manner. Figure 6 shows a standard postoperative x-ray control to confirm correct reduction and implant position.
Postoperative Treatment To minimize strain on the reconstructed CC ligaments, the shoulder is immobilized in a sling for 6 weeks postoperatively.
Figure 5 The drawing shows the PDS cerclage in a figure of eight for direct AC joint stabilization. The dotted lines mark the horizontal drill holes through the lateral clavicle (drilled from posterior to anterior) and the acromion (drilled from anterior to posterior aiming cranially). (Color version of figure is available online.)
Primary fixation of AC joint disruption
5 grade injuries (types I and II) should be initially managed nonsurgically, surgical management is typically recommended for high-grade lesions (types IV through VI) and in some type III lesions in heavy laborers or high-level athletes. Owing to the relatively high complication rates of modern AC reconstruction techniques, the authors currently prefer the described technique, using a single, small coracoclavicular drill hole. Although our early results are encouraging, investigation with long-term follow-up will be necessary to show the value and possible advantages of the procedure.
References Figure 6 The postoperative x-ray control confirms correct positioning of the implants and drill holes and the anatomical reduction of the AC joint.
Within the first 2 weeks, passive motion exercises are performed limited to 301 of flexion and abduction as well as to 801 internal rotation and 01 external rotation. At 3-4weeks, range-of-motion exercises are performed up to 451 flexion and abduction in an active-assisted manner. After 5-6 weeks, rangeof-motion exercises are advanced to 601 of flexion and abduction with an unlimited rotation. Active motion in the upright position is then advanced per the patient’s tolerance. After regaining pain-free full-active range of motion, strengthening exercises can start around the 12th postoperative week. Unrestricted return to work is usually allowed at 12-16 weeks after surgery. Patients are typically allowed to go back to fullcontact athletics after 5-6 months.35
Clinical Results Clinical results of modern anatomical arthroscopically assisted techniques for AC joint reconstruction with 2 drill tunnels have been favorable in midterm and long-term follow-ups.36,37 Nonetheless, these surgical techniques are highly demanding and dependent on the skills of the surgeon. In some cases, the anatomy of the patient may even exclude correct and safe positioning of the bone tunnels.38 It has been shown in the literature that only one bone tunnel for CC reconstruction can provide comparable clinical results.39 Primary stability of single-tunnel techniques (without additional AC joint cerclage) showed similar strength to the native ligaments in biomechanical testing but cannot yet reach the load-to-failure strength of double-tunnel techniques. To improve this stability, the authors recommended adding the AC joint cerclage with a PDS cord, which particularly reduces horizontal stability of the distal clavicle.32
Conclusion AC joint separations are common injuries and may lead to severe impairment of shoulder function. Numerous treatment options have been proposed in the literature. Although low-
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