How to Use a Graft in Irreparable Rotator Cuff Tears: A Literature Review Update of Interposition and Superior Capsule Reconstruction Techniques

Abstract

Purpose of Review

To introduce the challenges in addressing irreparable rotator cuff tears and examine the surgical options, specifically interposition grafting and superior capsule reconstruction.

Recent Findings

Interposition grafting of rotator cuff tears shows promising results in reducing pain and improving function postoperatively and one study demonstrated that it performs significantly better than partial repair alone. Superior capsule reconstruction has become popular rapidly, but given the novelty of the procedure, there is currently a paucity of outcomes data to review.

Summary

Irreparable rotator cuff tears are a challenging condition with a variety of surgical options available. Two such options—interposition and superior capsule reconstruction—both employ grafts in an attempt to restore joint stability and function. In the past 3 years, literature discussing interposition grafting has explored the different types of grafts, and mostly employed pre-post analysis. The recent superior capsule reconstruction articles strictly used human dermal allograft and offer a variety of surgical techniques without quantitative data.

Introduction

A rotator cuff tear (RCT) is a common pathology characterized by the tear of any one of the four tendons that compose the rotator cuff. The supraspinatus tendon, which inserts at the greater tuberosity, is most commonly affected, and a complete tear of the supraspinatus often results in pain, loss of function in arm abduction, and superior destabilization of the glenohumeral joint [1]. With an overall RCT incidence of 20%, and an incidence of 50% among individuals over 80 years of age [1, 2], this condition and the resultant pain, weakness, and impaired function represent a significant burden of disease in our society.

While many tears are asymptomatic, symptomatic tears not responsive to nonoperative treatment are frequently repaired, with approximately 250,000 repairs performed annually in the USA [3, 4]. Retear rates are high, 5–94% [5–7], with risk factors such as age over 65, fatty degeneration of over 50% of the rotator cuff muscle, tendon retraction, tobacco use, diabetes mellitus, and the size of the tear all predictive of structural failure of the repair [8, 9]. Counterintuitively, even in the setting of a retear, up to 90% of patients experience pain relief and functional improvement [1, 8]. Purported causes of this structural failure are mechanical forces at the repair site, and often specifically in relation to the poor healing environment and microanatomical changes that occur during the healing process [1, 9, 10].

Many treatment options exist for managing the irreparable RCT, including corticosteroid injections [11], tuberoplasty with biceps tenotomy and debridement [12, 13], partial rotator cuff repair [14], tendon transfers [15, 16], reverse total shoulder arthroplasty [17, 18], and even glenohumeral joint arthrodesis [19]. The focus of this review is to examine research within the last 3 years on the use of two types of grafting procedures for treatment of irreparable RCT: “interposition grafting” (IG), synonymous with gap-bridging, where the graft is used to bridge an irreparable gap between rotator cuff tendon and the rotator cuff footprint—not as an augment (which is frequently an “off-label” use); and “superior capsule reconstruction” (SCR) [9]. Each procedure can be used with a variety of graft materials including autograft, allograft, xenograft, and a variety of synthetic options available.

The most significant variations between the graft types involves their strength and antigenic properties; allografts and xenografts are more likely to be antigenic than synthetic or autografts, but are less available and have less potential for modification of their biomechanical properties than synthetic ones [9]. Unfortunately, even with the promise of biologic modification, the synthetic grafts currently available on the market generally are able to replicate either the biologic properties of the RC tendon or the mechanical properties, but not both, and have a retear rate as high as 62% [9, 20].

The focus of this review is the irreparable RCT, defined as a RCT with a gap between the rotator cuff tendon and the rotator cuff footprint that persists after a complete surgical attempt at tendon mobilization. This situation occurs frequently in massive RCT which have a defect of at least 5 cm and involvement of at least two tendons. The primary function of the rotator cuff is to dynamically maintain the joint center of rotation and avoid superior subluxation of the humeral head by resisting the upward vector of the deltoid muscle [21, 22]. Rotator cuff repair with IG attempts to restore this dynamic restraint to superior translation. With full thickness tears of the supraspinatus, the superior capsule is also damaged and its restraining effect against superior translation is compromised [1, 3]. SCR is a recently described technique that is designed to recreate the static superior stability imparted by this structure. As augmentation grafting is possible only in the subset of massive RCT that are repairable to some portion of the tuberosity, this technique, where a graft is placed on top of a RC repair to fortify its mechanical and biologic properties, will not be discussed here.

Interposition

A PubMed search was conducted for terms related to “rotator cuff, repair, massive, irreparable, interposition, gap-bridging, bridge, patch, graft, scaffold, augmentation,” and was filtered by results only published between October 1, 2014 and October 1, 2017 for this update. Only human, clinical studies, in the English language were included. Using these parameters, a total of 19 relevant results that pertain to IG in massive or irreparable RCT were returned [9, 11, 14, 23•, 24, 25•, 26•, 27•, 28•, 29–38]. Both types of RCT were included as massive and irreparable are occasionally used interchangeably in the literature. Publications on animal models were excluded from this section and are discussed separately below. Of note, only six clinical studies [23•, 24, 25•, 26•, 27•, 28•] were published during these prior 3 years on IG with one additional case report [37] and one strictly surgical technique paper [36]. The majority of articles returned were reviews that explored various repair options and outcomes that included massive and irreparable RCT [9, 11, 14, 29–35, 38]. As these reviews report largely on publications that occurred prior to this review’s time range, they are not discussed in detail below.

Prior to October 2014, many studies indicated that in massive and irreparable RCT repaired with grafts in the interposition configuration, that there is postoperative improvement in pain, various subjective measures, and range of motion (ROM) [14, 39–47]. Allografts, xenografts, and synthetic grafts all demonstrated some degree of improved postoperative functional status and high rates of healing (74–90%, 73–100%, 60–90%, intact at follow-up, respectively) [26•, 34, 42, 43, 48–56]. Autografts were found to be more likely to be structurally intact than partial primary repairs, with fascia lata (79%) more likely to be intact at 12 months than biceps tendon grafts (58%) [49, 50]. In reviews evaluating graft interposition versus augmentation studies, healing rates were found to be 78–88% when grafts were used in the interposition configuration and 64–66% when used in augmentation [30, 38].

Interposition Allografts

In 2014, Kokkalis et al. [25•] published a retrospective case series of 21 patients with massive RCT who were treated with an open repair utilizing interposition human dermal allograft. After an average follow-up interval of 29 months, all patients had significantly less postoperative pain, decreasing from 7.6 to 1.8 on a 0–10 visual analog scale (VAS) and improved forward flexion (77° to 139°), abduction (67° to 126°) and external rotation (ER) (9° to 47°). American Shoulder and Elbow Surgeons Shoulder Score (ASES) similarly improved from 25.2 to 74.3.

Dimitrios et al. [24] reported a prospective case series of 68 patients with interposition allografts in 2015, in which all subjects had irreparable RCT repaired operatively with fascia lata. At 12 months postoperatively, there was an increase in Constant Score (CS) from 32.5 preoperatively to 88.7, with a notable improvement in the pain subscore from 2.4 to 14.1. Postoperative MRI was performed on 10 patients with equivocal results, though ultrasound examination of 30 other patients at 12 months showed retear in only 3 of them. Statistical significance tests are not reported in this article and there was no comparison control group.

In 2017, Pandey et al. [23•] published a prospective, non-randomized cohort study of 26 patients with symptomatic, irreparable RCT who failed nonoperative management. The first 13 patients enrolled had only partial repair and the subsequent 13 patients underwent partial repair with an interposition GraftJacket dermal allograft. In keeping with prior literature, both procedures improved postoperative pain and function at 2 years. Partial repair significantly improved the Oxford Shoulder Score (OSS) from 17.8 to 37.1 and the CS from 43.1 to 70.8. The addition of the GraftJacket to the procedure also demonstrated postoperative benefit (14.9 to 43.9 for OSS and 41.2 to 83.9 for CS) but the postoperative scores for the allograft cohort were significantly higher than the partial repair alone on both measures. Three patients in the allograft cohort did retear, though no significant loss of function was noted in these patients when compared to the remaining 10 in their cohort.

Interposition Autografts

Fatty infiltration of muscle is a known risk factor in repairing RCT [8]. In 2013, Mori et al. found clinical improvement over partial repairs when interposition fascia lata grafts were used in RCT with Goutallier stage 1 or 2 fatty degeneration [50]. Building on this foundation, Mori and his colleagues [26•] recently conducted a cohort study in irreparable RCT patients with high-grade (Goutallier stage 3 or 4) supraspinatus fatty degeneration and any Goutallier stage (1–4) infraspinatus. They were divided into low grade, Goutallier stage 1 or 2 infraspinatus, and high grade, stage 3 or 4 infraspinatus, and all treated with an interposition fascia lata autograft. At 24 months postoperatively, significantly more low-grade shoulders (73.1%) were intact than the high-grade ones (10.6%), where 89.4% of the retears that occurred were of the infraspinatus. Both groups showed significant functional improvement in CS, ASES scores and ROM, though the low-grade cohort again consistently outperformed the high-grade shoulders.

The second interposition autograft study in the past 3 years was a small case series by Mihara et al. [27•] in which five irreparable RCT patients received an interposition iliotibial band with a Gerdy’s tubercle bone block [57]. They hypothesized that the bony autograft would provide more reliable healing than grafts solely composed of soft tissue. At 24 months postoperatively, statistically improved pain and subjective scores were noted, as measured by UCLA Shoulder Rating Scale, ASES, and the simple shoulder test. ROM improved postoperatively, but not significantly. Radiologically, bone block to greater tuberosity union on CT was confirmed at 3–4 months and intact repairs were noted in all five patients on MRI at 24 months. There was no donor site morbidity.

Interposition Xenografts

Neumann et al. [28•] used porcine cellular dermal matrix grafts to repair 61 irreparable RCT. This report is the first prospective study examining subjective and objective variables in this specific procedure, and has strengths of a lengthy follow-up (mean 50.3 months) and a large sample size for this type of study. They found that, postoperatively, there were significant improvements in pain, from 4.0 to 1.0 on VAS, forward flexion, ER and internal rotation (IR), supraspinatus and infraspinatus strength, and modified ASES score. 91.8% of cuffs were intact on ultrasound at follow-up as well, with 3.3% partially intact and only 4.9% not intact. However, following the Wright Medical-Tornier merger, this xenograft, which had been sold by Tornier, has been taken off the market in favor of Wright Medical’s Graftjacket. Of note, this decision was driven by post-merger corporate sales strategy, and not by any adverse events observed among these grafts.

Superior Capsule Reconstruction

A PubMed search was conducted for terms related to “rotator cuff, superior capsular reconstruction, SCR, massive, irreparable” and was filtered by results only published between October 1, 2014 and October 1, 2017. Twenty relevant results [3, 9, 11, 14, 31, 58–69, 70•, 71•, 72•] were returned, with animal models again excluded from this section. Again, for this update only human, clinical studies, in the English language were included. Ten of the articles revealed by the search were technique articles, nine of which detailed different SCR surgical techniques (see Table 1) [3, 11, 60–64, 66, 67], and one which elaborated on rehabilitation following SCR [59]. The remainder consisted of review articles [9, 14, 31], a case report [58], a cadaveric, radiologic study [65], and a series of biomechanical studies and two editorials on them [68, 69, 70•, 71•, 72•]. No clinical studies were identified during this 3-year period. This is perhaps a function of the relative novelty of SCR; it was only in 2012 that Mihata et al. published their seminal paper on the biomechanics and technique of SCR [73] and, in 2013, on its clinical outcomes [74].

Table 1.

Surgical technique SCR publications 10/2014–10/2017

Article	Acromioplasty	Biceps tenodesis/tenotomy	Partial repair	Arm positioning	Graft dimensions	Graft introduction technique	Anterior fixation
Hirahara and Adams (2015) [60]	/	Y	Y	0° Abd 0° Rot	+ 5 mm A/P/M/L	2 double-pulley systems	Anterior with caution
Petri, Greenspoon and Millett (2015) [61]	/	/	/	/	/	Traction on single glenoid anchor	Anterior to subscapularis
Tokish and Beicker (2015) [62]	Y	Y	/	20–30° Abd 0° Rot	+ 5 mm A/P/M + 12 mm L	Double-pulley	Anterolateral to subscapularis tendon
Katthagen, Tahal and Millet (2016) [63]	/	/	/	/	/	Arthroscopic knot pusher	Anterolateral to subscapularis
Thorsness and Romeo (2016) [11]	Y	/	Y	/	+ 5 mm A/P/M/L	Double-pulley	Advise against
Burkhart et al. (2016) [64]	Y	Y	Y	20–30° Abd 20° FF	+ 5 mm A/P/M + 10 mm L	Zip-line shuttle	Anterior to residual comma tissue
Narvani et al. (2016) [66]	Y	/	/	/	+ 5–10 mm A/P/M/L	Pull-over	/
Adams et al. (2016) [67]	Y	Y	Y	20–30° Abd 20–30° FF	+ 5 mm A/P/M +10 mm L	Double-pulley	Anterior to residual comma tissue
Sutter, Godin and Garrigues (2017) [3]	/	/	Y	30° Abd 20° FF 10° ER	+ 5 mm A/P/M +15 mm L	Double-pulley	Advise against

Key: /, not specified in article; Y, used by authors; graft dimensions, the number of millimeters added to graft beyond distances measured in vivo; graft introduction technique, how graft is introduced to shoulder and guided to superior glenoid; anterior fixation, refers to author decision to fix the anterior graft to adjacent tissue; Abd, abduction; Rot, rotation; A, anterior; P, posterior; M, medial; L, lateral; FF forward flexion; ER, external rotation

In Mihata et al.’s original case series [74], outside the time frame of this review update, the authors completely repaired the subscapularis tendon, partially repaired the infraspinatus and teres minor tendons, then performed SCR using a folded, 6–8-mm thick fascia lata autograft. Two suture anchors were used for medial fixation to the superior glenoid and lateral fixation was done with the compression double-row technique. Their final step was to suture the graft posteriorly to the infraspinatus tendon and anteriorly to the residual supraspinatus or subscapularis tendons to improve force-coupling. At the final follow-up (24–51 months, mean 34.1 months), this approach yielded a postoperative increase in mean ASES, Japanese Orthopedic Association, and UCLA scores—23.5 to 92.9, 48.3 to 92.6, and 9.9 to 32.5, respectively. ROM and strength were similarly improved at 2 years, with significant benefit seen in elevation, ER and IR. Postoperative imaging revealed an increased acromiohumeral distance from 4.6 to 8.7 mm, indicative of reversal of superior humeral subluxation [64], and an 83.3% rate of intact repairs throughout the follow-up.

Since this time, multiple variations on this theme have emerged, and are detailed below, as are the recent publications that further examine the biomechanics of this relatively new technique. While the criteria for electing to perform SCR have not been completely codified, these repairs generally are used in the massive, irreparable, posterosuperior RCT among young or active patients who do not have arthritis. In the practices of the senior authors (APT, GEG), this typically represents patients between 50 and 70 with supraspinatus or infraspinatus tears retracted to, or just medial to, the glenoid, with at least Goutallier stage 3 fatty infiltration. The primary contraindication to this procedure is a fixed, high-riding humeral head. However, it should be noted that if radiographs demonstrate an acromiohumeral interval (AHI) of > 7 mm, or if the AHI is narrowed but can be reduced to a normal station with sulcus maneuver, then there is sufficient mobility for humeral head reduction and use of a stabilizing SCR graft.

Surgical Techniques

All nine SCR surgical technique articles stayed mostly true to Mihata’s original approach with no change to the basics of graft fixation—medially to the superior glenoid, laterally to the greater tuberosity, and finally posteriorly to the infraspinatus tendon. However, no other authors have used fascia lata as Mihata did; instead, recent reports have opted for a human acellular dermal allograft with a thickness of 3.0–3.5 mm, with the potential benefits of eliminating any donor site morbidity and reducing operative time [3, 67]. The authors all also performed diagnostic arthroscopy upon entering the shoulder, but after this point in the operation, the techniques vary until the relatively similar lateral double-row fixations. The various steps and operative decisions that authors describe in these technique articles are detailed in Table 1, and further elaboration on some of the more significant differences and proposed advantages are below. The lack of published postoperative outcomes makes comparisons between these technique variations impossible and all advantages and disadvantages are thus theoretical.

The decision to perform acromioplasty, biceps tenodesis or tenotomy, and/or partial repair appear, to date, to be matters of surgeon preference in SCR operations, with little commentary offered in the literature on why each author made the decision to perform any one of these specifically during SCR beyond their standard indications. Arm position when fixing the graft laterally, while also seemingly a matter of preference, is described by Sutter and his colleagues as critical for ensuring the graft is taut under low degrees of abduction [3]. They achieve this by putting the patient’s arm at 30° abduction, 20° forward flexion, and 10° external rotation. The other authors who mention position usually follow a similar set-up, with the range for abduction between 0° and 30°, as supported by Mihata’s biomechanical studies below, forward flexion 20–30° and rotation neutral to 10° [70•].

Nearly all grafts have 5 mm added to the anterior, posterior, and medial dimensions to prevent suture pullout. A caveat to these measurements is that while some authors measure the corners of the prepared glenoid and greater tuberosity footprints [62], others place anchors first, then measure the distances between them [3, 11, 60, 64, 67]. Hirahara argues that use of the latter method creates a more accurate graft size that better matches the defect [60]. On the lateral edge of the graft, a range of 5–15 mm is described [3, 60, 62, 64, 67], with greater sizes being used to more adequately cover and interface with the prepared greater tuberosity footprint.

The greatest differentiator in published techniques was in the method used by the authors to introduce the graft to the shoulder and bring the medial edge to the superior glenoid. Some authors simply push the graft into place with an arthroscopic knot pusher [63] while others follow Mihata’s example and use the double-pulley technique [3, 11, 62, 67]. In this method, a limb of each suture—anterior and posterior—running from the glenoid anchors through a lateral portal and to the medial graft are tied together. Thus, when the remaining free limbs are pulled, the glenoid anchors act as two pulleys that slide the graft into place. Hirahara and Adams introduced a modification of this system by using two double-pulleys. In this, they again passed two limbs from the medial anchors through the graft then tied them together, but then also repeated this with two limbs from the greater tuberosity anchors. The graft may then be introduced with traction on each double-pulley system’s remaining free limb, theoretically leading to more accurate graft placement and less graft and suture tangling [60].

Burkhart et al. [64] also modified the double-pulley system with their “zip-line shuttle,” which was originally designed for large grafts that become trapped or meet enough resistance in the cannula that the force on the double-pulley system will pull out a glenoid anchor. The authors first place a third, central glenoid anchor, a step shown in a radiographic study to be at low risk of damaging the suprascapular nerve or disrupting the glenoid fossa [65]. This anchor sits between the standard anterior and posterior ones, with one end of its suture limbs passing through a modified Neviaser portal and the others through a lateral portal. The lateral portal suture limbs are then tied to the graft, while the anterior and posterior anchor suture limbs are passed through their respective holes in the graft, but not tied together; these serve as the zip-lines that the graft may slide down when traction is applied to the central anchor suture limbs exiting the modified Neviaser portal.

Burkhart et al.’s procedure is comparable to Narvani et al.’s pull-over technique [66], in which traction on sutures passing through a Neviaser portal is also used to introduce the graft, though Narvani et al. use only two standard glenoid anchors. In this technique, anterior and posterior suture limbs from the glenoid anchors are passed out of the lateral portal, through their respective holes in the graft, then shuttled back into the shoulder using polydioxanone suture and out of the Neviaser portal so that upwards traction, directly above the glenoid anchors, will pull over the graft into place. The suggested advantage is that this approach mitigates some of the technical difficulty of pushing the graft into place, suture tangling, and graft rotation.

The final graft introduction variation was proposed by Petri, Greenspoon, and Millet [61] in which a third, central glenoid anchor is placed at 12 o’clock. Its suture is fixed to the center of the graft’s edge and traction on the remaining free limbs and an arthroscopic knot pusher are used to introduce the graft. From there, a permanent braided suture tape that already passed through the centromedial graft is loaded into the anterior glenoid anchor along with a braided loop of permanent suture already in the anteromedial graft, thus fixing the graft to the glenoid anteromedially. The same steps are then repeated for posteromedial fixation.

The final step in most SCR procedures involves some degree of side-to-side fixation where the posterior aspect of the RCT is sutured to posterior edge of the graft. As Mihata demonstrated in biomechanical studies, this posterior fixation helps SCR achieve its goal of stabilizing the humeral head and preventing superior subluxation [70•]. Anterior fixation to the subscapularis muscle remains controversial. Multiple authors recommend against this [3, 11], as it has the potential to close the rotator interval and thus restrict ROM [3] but some authors however (see Table 1), do advocate for anterolateral fixation to the subscapularis tendon or to residual “comma” tissue [62, 64, 67].

Ultimately, despite the numerous permutations of these approaches, no SCR data beyond Mihata’s original case series was found in the literature, though two surgical technique papers allude to unpublished data demonstrating improvement in pain and functional outcomes [63, 67]. Additional data are needed, whether that is in case series or in comparative studies, for validation of SCR as an effective technique for irreparable RCT, and for evidence to support each variation. Indeed, the only publication highlighting a failure of SCR in the past 3 years of literature is a case study published in 2017 by Zerr et al. which documented one occurrence of allograft detachment from its glenoid anchor at approximately 6 months post-SCR that presented with pain and limited ROM [58]. The patient underwent repeat SCR with graft reattachment to new anchors but pain and an unchanged physical exam persisted at the time of publication, 7 weeks postoperatively. While certainly not the sole case of SCR failure, this limited report highlights the field’s need for further research on this rapidly evolving technique.

Biomechanical Studies

Between 2015 and 2016, Mihata and his colleagues conducted a series of cadaveric, biomechanical studies on irreparable tears and SCR that now inform the techniques of this approach. Not only was the tendency of the humerus to translate superiorly and have increased subacromial contact pressure in the presence of irreparable supraspinatus tears demonstrated, thus providing the rationale behind SCR [70•, 71•], but methods for correcting this were also investigated. The authors used fascia lata in 4 or 8-mm thickness to perform SCR with the arm between 0° and 30° abduction. They noted that both graft sizes decreased contact pressure, with the 8 mm graft paradoxically reducing this pressure more so than the 4 mm graft, while also preventing superior translation [70•]. It was also shown that fixing the graft posteriorly to residual infraspinatus tendon similarly decreased contact pressure and prevented superior translation when compared to SCR without this posterior side-to-side suturing [72•]. Finally, they demonstrated that in this irreparable supraspinatus tear population, adding acromioplasty to SCR will decrease subacromial contact area, though not pressure [71•]. In this fashion, the risk of the graft being damaged by the acromion is theoretically reduced. As the literature from the prior 3 years shows, the field has followed the path laid by Mihata: acromioplasty is frequently, albeit not always, used, arms are positioned around 30° for graft measurement and placement, and posterior fixation to the infraspinatus is universal.

Animal Studies

Three animal studies, all comparative, were found that were relevant to interposition grafts or SCR [75–77]. In the first two, interposition grafts were used in simulated irreparable RCT and then underwent biomechanical testing alongside direct repair with native tendon—possible because the “irreparable RCT” in these models were not truly irreparable. Mckeown et al. found that while a physiologic ovine tendon-bone unit had a higher load-to-failure than the two grafts they used—polytetrafluoroethylene and expanded polytetrafluoroethylene—both grafts were stronger than the native tendon and bone once they had been separated and directly repaired [75]. Smith et al. similarly found that a graft consisting of demineralized bone matrix hydrated in platelet-rich plasma showed improved strength, and appearance both histologically and on MRI when compared to direct repair in canine infraspinatus tendon tears [76]. Finally, Lee et al. also utilized growth factor-laden grafts, albeit in augmentation, not in interposition or as part of SCR. They coated human acellular dermal grafts, which are widely used in SCR and thus why this study was included in this review, with BMP-2 which demonstrated improved tensile strength over grafts without BMP-2 and additionally promoted new bone formation better with newly differentiated fibrochondrocytes present at the graft-bone interface [77]. These studies, while affected by the limitations of the animal models, provide a tantalizing glimpse into potential future options for grafts, including biologically active ones, for irreparable RCT.

Conclusion

Restoring the irreparable RCT is an important clinical issue and a difficult surgical challenge. Basic science literature and animal models suggest a role for using growth factors as an adjunct to grafts to create a more favorable milieu for healing. Clinically, our review of the last 3 years showed no known literature comparing interposition and superior capsule reconstruction, and most studies on the individual technique variations do not use a control group or a randomized design. Thus, it is difficult to definitively assess the outcomes of interposition grafting and superior capsule reconstruction. Structured research with appropriate control populations will be necessary to determine if the added expense, operative time, and potential morbidity of these procedures is indeed justified.

Compliance with Ethical Standards

Conflict of Interest

Alison Toth reports a grant and personal fees from Tornier, both of which ended in 2015.

Grant Garrigues reports personal fees from Tornier/Wright medical and DJO/Encore medical, and grants and fellowship support from Arthrex and Smith and Nephew.

Kevin Wall declares that he has no conflict of interest.

Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.