Radiographic failure and rates of re-operation after acromioclavicular joint reconstruction

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1 H. T. Spencer, L. Hsu, J. Sodl, A. Arianjam, E. H. Yian From Kaiser Permanente Orange County Anaheim Medical Center, California, United States H. T. Spencer, MD, Orthopaedic Surgeon, Department of Orthopaedic Surgery L. Hsu, MD, Orthopaedic Surgeon, Department of Orthopaedic Surgery J. Sodl, MD, Orthopaedic Surgeon, Department of Orthopaedic Surgery A. Arianjam, MD, Orthopaedic Surgeon, Department of Orthopaedic Surgery E. H. Yian, MD, Orthopaedic Surgeon, Department of Orthopaedic Surgery Southern California Permanente Medical Group, 3460 East La Palma Avenue Anaheim, California, 92806, USA. Correspondence should be sent to Dr E. Yian; The British Editorial Society of Bone & Joint Surgery doi: / x.98b $2.00 Bone Joint J 2016;98-B: Received 24 February 2015; Accepted after revision 2 November 2015 SHOULDER AND ELBOW Radiographic failure and rates of re-operation after acromioclavicular joint reconstruction A COMPARISON OF SURGICAL TECHNIQUES Aims To compare radiographic failure and re-operation rates of anatomical coracoclavicular (CC) ligament reconstructional techniques with non-anatomical techniques after chronic high grade acromioclavicular (AC) joint injuries. Patients and Methods We reviewed chronic AC joint reconstructions within a region-wide healthcare system to identify surgical technique, complications, radiographic failure and re-operations. Procedures fell into four categories: (1) modified Weaver-Dunn, (2) allograft fixed through coracoid and clavicular tunnels, (3) allograft loop coracoclavicular fixation, and (4) combined allograft loop and synthetic cortical button fixation. Among 167 patients (mean age 38.1 years, (standard deviation (SD) 14.7) treated at least a four week interval after injury, 154 had post-operative radiographs available for analysis. Results Radiographic failure occurred in 33/154 cases (21.4%), with the lowest rate in Technique 4 (2/42 4.8%, p = 0.001). Half the failures occurred by six weeks, and the Kaplan-Meier survivorship at 24 months was 94.4% (95% confidence interval (CI) 79.6 to 98.6) for Technique 4 and 69.9% (95% CI 59.4 to 78.3) for the other techniques when combined. In multivariable survival analysis, Technique 4 had better survival than other techniques (Hazard Ratio 0.162, 95% CI to 0.068, p = 0.013). Among 155 patients with a minimum of six months postoperative insurance coverage, re-operation occurred in 9.7% (15 patients). However, in multivariable logistic regression, Technique 4 did not reach a statistically significant lower risk for re-operation (odds ratio 0.254, 95% CI 0.05 to 1.3, p = 0.11). Conclusion In this retrospective series, anatomical CC ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. Take home message: Anatomical coracoclavicular ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. Cite this article: Bone Joint J 2016;98-B: Acromioclavicular joint (ACJ) injuries are common, representing 9% to 12% of all injuries to the shoulder girdle. 1,2 The majority of these injuries occur in the athletic population, most commonly in males in their second and third decade. 3-5 Almost 80% are low-grade (Types I, II) injuries 6 and good outcomes can be anticipated with non-operative management, averaging time lost to injury of only 10.4 days. However, higher grade injuries (Types III to VI) may require surgical intervention with a longer recovery period. 4 More than 60 different techniques have been described to reconstruct the coracoclavicular (CC) ligament complex after chronic injury, however, the optimal reconstructive technique has not been defined. 7,8 Numerous cadaveric investigations have compared techniques, 5,8-14 however, there have been few large clinical studies to guide treatment. 15 There is widespread acceptance that non-anatomical reconstructions are biomechanically inferior to anatomical reconstruction techniques based on laboratory testing. However, overall complication rates of 512 THE BONE & JOINT JOURNAL

2 RADIOGRAPHIC FAILURE AND RATES OF RE-OPERATION AFTER ACROMIOCLAVICULAR JOINT RECONSTRUCTION 513 anatomical reconstruction techniques have exceeded 50% in some studies, with the most common modes of failure being early loss of reduction, implant failure, and fracture. 16 The purpose of this study was to compare failure rates of anatomical CC ligament reconstruction techniques with non-anatomical techniques after chronic high grade AC joint injury within a large region-wide integrated healthcare system. Secondary objectives included analysing the influence of age, gender, tobacco use, separation grade, and hand dominance. We hypothesised that the radiographic failure rate and rate of re-operation would be equal across groups. Patients and Methods Approval was obtained from the Institutional Review Board at our institution. We performed a retrospective review of ACJ separations treated surgically between 2008 and 2012 within a region-wide healthcare organisation. Patients were identified through searching an electronic database using a broad range of diagnostic and procedure codes in order to capture all potential cases. Individual review of medical records was then performed by one of the authors (EHY) to exclude patients recorded with problems unrelated to the ACJ. Inclusion criteria were patients with an isolated ACJ injury treated with either an anatomical or non-anatomical CC ligament reconstruction. We excluded patients with associated fracture or polytrauma and patients with prior surgical treatment of the ACJ. Acute injuries were defined as those treated surgically within four weeks of injury and were excluded from our analysis. The treating surgeon determined the post-operative protocol and follow-up regime. Operative reports were individually examined to determine the reconstructive technique used. Cases in which CC fixation was performed with synthetic fixation alone (suspensory button) were excluded. Other techniques were divided into four categories based on the method of CC fixation: non-anatomical procedures (modified Weaver-Dunn, namely, transfer of the coracoacromial ligament and supplementary suture-only fixation around the CC space), 17 CC reconstruction with allograft fixed through coracoid and clavicular tunnels, CC reconstruction with allograft looped around the coracoid, CC reconstruction with combination of synthetic fixation and allograft loop around the coracoid. 8,17 Patient age, gender, hand dominance, comorbidities, tobacco use, and ACJ separation grade were assessed. Post-operative anteroposterior radiographs were reviewed to determine radiographic failure (EHY, LH). Radiographs which did not reach a consensus were jointly reviewed. Radiographic failure was defined as an increased CC interval of > 5 mm compared with immediate post-operative radiographs. In cases with radiographic failure, time from surgery until failure was documented for survival analysis. In a separate analysis, post-operative medical records were reviewed to assess for re-operation. Insurance records were used to identify all patients with at least six months health care coverage post-operatively in this analysis. The integrated nature of our healthcare system ensured that reoperation would be captured as long as the patient remained within the insurance network. Complications leading to re-operation were recorded. Statistical analysis. This was performed with Stata/IC 12.1 (StataCorp., College Station, Texas) using Fisher s exact test for categorical variables and the Kruskal-Wallis test for continuous measures. Correlations were performed with the Spearman s rank correlation coefficient test. The Kaplan-Meier survivor function with 95% confidence intervals (CI) and log rank test was calculated to compare the rate of failure between groups over time. Group survivorship for patients with no radiographic failure was calculated at 24 months after surgery. Patients with follow-up less than 24 months were censored in the survival analysis. Univariate and multivariable Cox proportional hazards modeling was performed to identify variables related to time to failure, and logistic regression was used to identify risk factors for re-operation. A p-value 0.05 was considered statistically significant. Results A total of 206 CC ligament reconstructions performed by 56 surgeons for isolated ACJ separation were identified through our database search. The mean age of this patient cohort was 38.1 years (standard deviation (SD) 14.7) and there were 29 female and 177 male patients. A total of 18 patients had surgical treatment using synthetic fixation alone and were excluded. There were 21 other patients excluded because they had undergone surgical treatment within four weeks of injury. Of the remaining 167 cases, 31 patients underwent non-anatomical modified Weaver- Dunn reconstruction (Technique 1). In all, 17 patients were reconstructed with allograft that was passed through tunnels in both the coracoid and clavicle (Technique 2). A total of 73 patients underwent reconstruction with allograft looped around the coracoid base (Technique 3). Lastly, 46 patients were treated with CC ligament reconstructions using both synthetic cortical button fixation and allograft looped underneath the base of the coracoid (Technique 4). Radiographic failure. For analysis of radiographic failure, all post-operative radiographs were reviewed and 13 patients were excluded for lack of post-operative imaging and of the remaining 154 patients (22 female, 132 male) with radiographic follow-up (mean 15.7 months, SD 16.2), the overall rate of failure was 33/154 (21.4%). Comparing surgical techniques, there was a statistically significant difference in the rate of radiographic failure (p = 0.001, Fisher s exact test), with the rate of failure in Technique 4 (2/42, 4.8%) being lower than in other groups (Table I). The length of follow-up did not differ significantly between groups (p = 0.873, Kruskal-Wallis test). VOL. 98-B, No. 4, APRIL 2016

3 514 H. T. SPENCER, L. HSU, J. SODL, A. ARIANJAM, E. H. YIAN Table I. Radiographic success and failure, by surgical technique group Technique Missing radiographs - excluded cases No failure Failure (%) Total p-value (30.8) (47.1) (21.7) (4.8) 42 Total (21.4) Fisher s exact test Table II. Univariate predictors for radiographic failure, Cox proportional hazards Hazard ratio 95% confidence interval p-value Age to Gender to Smoker to Injured side was dominant hand to Grade of separation 2 1 (reference) to to to Technique 1 1 (reference) to to to Technique 4 vs all others to Other 1 (reference) Use of interference screw fixation to Distal clavicle excision with surgery to High-volume surgeon (10 or more cases) to Arthroscopic surgery to Time to surgery, continuous (days) to Table III. Multivariable model for Radiographic Failure, Cox proportional hazards Hazard ratio 95% Confidence interval p-value Age to Gender to Technique 4 vs others to Time to surgery, continuous (days) to For survival analysis, the time to radiographic failure was analysed using univariate and multivariable Cox proportional hazards models. Univariate analysis showed that Technique 4 was associated with the lowest failure rate whether looking at all techniques individually (hazard ratio (HR) = 0.14, p = 0.012) or comparing Technique 4 to all other techniques combined (HR = 0.16, p = 0.013) (Table II). Age, gender, tobacco use, operative side dominance, grade of injury, distal clavicle excision, time to surgery, arthroscopically assisted surgery, use of interference screw fixation, and operative volume of the surgeon, were not statistically significant. For multivariable analysis, the grade of injury and surgeon volume were tested and were not found to be significant predictors and did not add to the significance of the model so were dropped from the model for parsimony. The final multivariable model is shown in Table III. The use of Technique 4 remained associated with a significantly lower HR for radiographic failure in the multivariable model. Most radiographic failures were noted to occur in the early post-operative period, with 50% of failures overall, occurring by six weeks after the index operation. Using the Kaplan-Meier method, survivorship at 24 months was calculated to be 94.4% (95% CI 79.6 to 98.6) for Technique 4 and 69.9% (95% CI 59.4 to 78.3) for the other techniques. Survival curves adjusted for covariates from the multivariable Cox proportional hazards model were plotted for cases performed with Technique 4 versus all other techniques and are shown below (Fig. 1). Technique 4 demonstrated superior survival against radiographic failure (HR 0.162, p = 0.013). Re-operation. Insurance records identified 190 of the 206 patients (92.2%) who maintained health care coverage for six months or longer post-operatively and of these, 16 cases had surgical treatment using synthetic fixation alone and were excluded. A total of 19 other cases were excluded for THE BONE & JOINT JOURNAL

4 RADIOGRAPHIC FAILURE AND RATES OF RE-OPERATION AFTER ACROMIOCLAVICULAR JOINT RECONSTRUCTION 515 Proportion surviving without radiographic failure All other techniques Technique 4 p = Days Fig. 1 Graph showing the Cox covariate-adjusted survivor functions, Technique 4 versus all others. Table IV. Rates of re-operation for each surgical technique Re-operation Technique Yes (%) n Total 1 4 (13.3) (14.3) (10.3) (4.7) Technique 4 Yes 2 (4.7) No 13 (11.6) Total 15 (9.7) p = Table V. Reasons for re-operation Diagnosis Procedure Patients (n = 15) * Radiographic failure Revision ACJ reconstruction 8 * Infection * Incision and drainage 4 * Symptomatic ACJ arthrosis Distal clavicle excision 2 Adhesive capsulitis Manipulation under anaesthesia 2 Loose implant * Removal of implant and I&D 1 * * One re-operation was performed in a patient with both radiographic failure and wound infection ACJ, acromioclavicular joint Table VI. Multivariable logistic regression model for re-operation Odds ratio p-value 95% confidence interval Patient aged > 40 yrs to 9.9 Technique 4 vs all others to 1.3 Use of interference screw fixation to 5.1 Arthroscopic surgery to 26.8 Distal clavicle excision with surgery to 7.8 Area under receiver operating characteristic curve having undergone acute surgical treatment (less than four weeks after injury), leaving 155 chronic reconstruction cases for analysis of all-cause re-operation. In all, 15 patients with 17 complications underwent re-operation which represented an overall rate of 9.7% (Table IV). Reasons for re-operation were diverse (Table V), with only eight of the15 re-operations occurring in patients who had experienced radiographic failure. In addition, there was no significant correlation found between the time to radiographic failure and the time to re-operation (Spearman s rho 0.44, p = 0.32). Technique 4 demonstrated the lowest apparent rate of re-operation (2/43 cases) in univariate analysis but did not reach statistical significance (p = 0.238). Moreover, in multivariable logistic regression VOL. 98-B, No. 4, APRIL 2016

5 516 H. T. SPENCER, L. HSU, J. SODL, A. ARIANJAM, E. H. YIAN (area under ROC curve = ), although Technique 4 was associated with a four-fold lower risk for re-operation versus other techniques (odds ratio (OR) 0.25), this finding did not demonstrate statistical significance (p = 0.11). Patient age over 40 years had a borderline significance for increased risk of re-operation (OR 3.1, p = 0.05) (Table VI). Other complications besides radiographic failure and reoperation included two clavicle fractures, two events of wound dehiscence (or) superficial infection, four instances of coracoid fixation button migration and three episodes of clavicular fixation button migration. Another re-operation was performed in a patient with both a loose implant and wound infection. Discussion The present study suggests that CC ligament reconstruction with allograft loop around the coracoid combined with cortical button fixation (Technique 4) was associated with improved radiographic survival in our patients. To our knowledge, this is the first study demonstrating a difference in radiographic outcomes with cortical button and suture fixation combined with allograft augmentation after chronic injury in a large cohort. Though Grassbaugh et al 15 demonstrated superiority of cortical button and suture fixation in a prior study, incomplete medical records led to difficulty in accurately identifying injury chronicity within their dataset, which may have skewed outcomes in these different patient groups. Earlier studies, in fact, showed a high rate of failure with the suspensory button device, but lacked data homogeneity by combining acute with chronic injuries or not supplementing with allograft augmentation. 16,18,19 Lim et al 18 had failure in four out of eight cases with the suspensory button device within two to six weeks. However, the authors did comment that they were at the start of their learning curve. Scheibel et al 20 repaired 28 patients with acute AC injuries with the use of a double suspensory button technique and saw 42.9% of their cases with less than optimal outcomes. Those cases demonstrated posterior instability, which accounted for decreased Taft and Acromioclavicular Joint Instability scores. 20 Salzmann et al 19 followed 23 patients for a mean of 30 months and had radiographic failure of 34.8%; these patients demonstrated undercorrection, posterior displacement, or both. In addition, there were five patients who had been overcorrected, although these patients did not show any clinical difference with respect to outcome. Milewski et al 16 looked at 27 cases of both acute and chronic AC joint reconstructions. The authors pointed out that eight of the ten cases had coracoid tunnel button fixation to pass graft or suture failed, whereas only 35% of their 17 cases that looped around the coracoid failed. Over the past few years, the surgical treatment of ACJ injuries has evolved leading to biomechanical studies evaluating different reconstruction techniques. Historically, biomechanical studies did not address the addition of a suspensory button with suture, but instead focused on variants of allograft reconstruction with or without comparison to the modified Weaver-Dunn procedure. 8,9,13,17,21 Recent biomechanical data have focused on variations of anatomical reconstruction techniques, including reconstruction of the AC ligament. 22,23 Whether these in vitro results correlate with clinical outcomes has yet to be determined. Zooker et al 24 were among the first to demonstrate biomechanically the advantage of a suspensory button to previously described ACJ reconstruction techniques. Supplementing Zooker et al s 24 study, Beaver et al 10 revealed that resection of the distal clavicle did not significantly affect superior-inferior or anterior-posterior movement after single tunnel ACJ reconstruction. Similarly, we found no association between procedures including a distal clavicular excision and revision or radiographic rates of failure, although our study only measured vertical translation. More recently, Nüchtern et al 14 demonstrated that the suspensory button had load to failures and stiffness that was comparable with the hook-plate and superior to tenodesis screw techniques. Clavicular tunnel placement and size has also been examined in the biomechanical literature. Cook et al 25 recently showed that placing the clavicular tunnels too medial during anatomical reconstruction could be a significant risk factor for early failures. Geaney et al 12 showed that optimal bone density is found at the anatomical sites of insertion located between 20 mm and 50 mm from the distal end of the clavicle. In addition, Kraus et al 26 demonstrated that double suspensory button fixation yields good to excellent clinical results in both V-shaped and parallel drill hole placement. Finally, literature by Spiegl et al 27 found that larger 6 mm tunnels used with tenodesis screw fixation resulted in a significant reduction in clavicular strength when compared with 2.4 mm tunnels used with cortical flip buttons. Recently, Martetschlager et al 28 described their experience after ACJ reconstruction and described a 27% complication rate with use of cortical fixation buttons or tendon grafts in a series of 59 procedures in 55 patients. They noted that two of ten post-operative clavicular fractures occurred through interference screw holes, an observation which had previously been reported by Milewski et al. 16 In our study, we noted one post-operative clavicular fracture through interference screw drill holes in the clavicle and one intra-operative clavicular fracture through the drill hole. We did not find a statistical relationship between clavicular fixation method (clavicular interference screw fixation vs looped allograft fixation) and radiographic failure in the suspensory button group. However, there were multiple examples in our study where the cortical fixation button changed position in follow-up radiographs, highlighting the risk when using hardware for this type of reconstruction. We have reviewed the results of a large cohort of patients treated with various techniques within a regional integrated THE BONE & JOINT JOURNAL

6 RADIOGRAPHIC FAILURE AND RATES OF RE-OPERATION AFTER ACROMIOCLAVICULAR JOINT RECONSTRUCTION 517 health care system. Whilst numerous comparative biomechanical studies exist, this is the largest cohort study to compare radiographic survival and rates of re-operation of these surgical techniques. Past case series have shown that suspensory button reconstructions can be successful even without allograft fixation In our study we found a lower rate of radiographic failure when the suspensory button was combined with an allograft looped around the coracoid. Zooker et al 24 demonstrated that isolated suspensory CC suture fixation without using allograft failed after 1500 load cycles, demonstrating the need for biological tissue reconstruction of the CC ligaments. We hypothesised that by combining the methods of fixation, the suspensory button would shield the allograft from stretch during the initial vulnerable phase of biological healing, while the allograft maintains long-term reduction after incorporation. Also, by looping the graft around the coracoid, this avoids drilling a hole through the coracoid, therefore reducing the potential for iatrogenic fracture. 11 Loss of reduction is one of the most common complications of CC ligament reconstruction. Multiple factors may lead to radiographic loss of reduction and radiographic failure, including surgeon experience, operative technique, and patient-related issues such as rehabilitation and non-compliance. We found a 21.4% overall loss of radiographic reduction, which is consistent with the 24% to 29% rate seen in the literature. 16,21,25,31 While many of these cases are clinically asymptomatic, such a high rate of an undesirable outcome warrants diligent attention. In a cohort of 37 patients, Lädermann et al 21 demonstrated improved Disabilities of the Arm, Shoulder, and Hand (DASH) 32 and Constant 33 scores when the CC interval of the operative shoulder was maintained within 5 mm of the contralateral side. We found an overall rate of re-operation of 9.7%. In a retrospective review of 90 patients comparing different methods of CC reconstruction, Grassbaugh et al 15 found a similar 9% rate of re-operation. Milewski et al 16 found a much higher rate of re-operation of 52% (14/27 patients) when comparing anatomical techniques. They likewise found that the most common aetiology of re-operation was failed ACJ reconstruction. However, because there are multiple surgeon and patient related factors that influence the decision for re-operation, it is difficult to compare objectively rates of re-operation among studies. Surprisingly, our re-operation group had a significantly higher age compared with our primary group. This may reflect patient-driven factors such as the patients wishes to undergo revision surgery, bone quality or soft tissue quality. Since the incidence of radiographic failure remains high for a procedure that is often performed in a young, active population, we believe that reconstruction should be reserved for high-grade (types four to six) injury or when conservative management has failed. The use of an arthroscopically assisted method was not found to have a higher failure rate in the present study compared with all open methods. However, the personal experience of each surgeon with this technique may have contributed to failure. A recent study at a single-centre institution suggests that arthroscopic reconstruction methods may be successful. 28 However, elsewhere arthroscopic assisted techniques, including stabilisation with coracoid tunnels, have shown high failure rates. 25 Repair and tightening of the delto-trapezial fascia over the clavicle during open reconstruction may augment the open procedure leading to a stronger repair. Our investigation carries limitations due to the retrospective nature of this review. We limited our outcomes to re-operation and radiographic failures, which are objective measures. There was variation of follow-up and post-operative protocols among surgeons that may have influenced our outcomes, but individual surgeons were consistent with their own post-operative protocols and all surgeons specified at least four weeks of sling immobilisation and restricted load bearing. In order to increase the statistical power of our investigation, we grouped surgical techniques into just four categories based only on the method of CC ligament reconstruction, however, such grouping did not consider the influence of additional ACJ capsular reconstruction techniques which may affect overall stability. 22,23 In conclusion, in a large retrospective cohort study comparing different surgical techniques for acromioclavicular reconstruction after chronic injury, we found anatomical CC ligament reconstruction with cortical button combined with loop fixation of allograft around the coracoid to have the lowest radiographic failure and rates of re-operation. This finding is important due to the overall lack of consensus in the literature supporting an optimal surgical technique for CC ligament reconstruction. The suggestion that surgical technique may influence radiographic survival and re-operation should be interpreted as a call for further prospective studies. 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