Editorial Commentary: Superior Capsular Reconstructions in Cases of Irreparable Rotator Cuff Tendons Only Partially Restore Anatomy, Yet Significantly Normalize Biomechanics-Without Resorting to Reverse Anatomy.

The goal of shoulder superior capsular reconstruction and/or anterior cable reconstructions, at least in terms of biomechanics, is to primarily restore a fulcrum to assist with pain control and functional optimization, with the secondary hope of maintaining cartilage. Fully restoring glenohumeral joint loads with SCR cannot be expected in the setting of persistent tendon insufficiency. Biomechanical studies characterizing shoulder capsular reconstructions have demonstrated anatomic and functional restorations toward normalization when tested with standard biomechanical methods. Glenohumeral abduction, superior humeral head migration, deltoid forces, and glenohumeral contact pressure and area, can be optimized toward the normal intact condition, as measured by motion tracking and pressure mapping in real time, using dynamic actuators. Insofar as restoring normal native anatomy is considered a fundamental priority, with the idea that joint functional longevity is enhanced by preserving anatomy, as surgeons, we should not lose sight of reconstruction over replacement (such as nonanatomic reverse total shoulder arthroplasty) as a favored goal. Anatomy-based reconstructions such as superior capsule or anterior cable reconstruction, may prove over time to be the best primary treatment as knowledge and innovations (technical and medical) develop, with nonanatomic arthroplasty truly being a last resort (yet a clinically viable option when indicated).

Anterior Cable Reconstruction: Prioritize Rotator Cable and Tendon Cord When Considering Superior Capsular Reconstruction.

Although distinct in name, the anterior cable of the superior capsule and tendon cord of the supraspinatus are structurally one in the same at the attachment on the greater tuberosity footprint. Force transmission through both structures where they converge and interdigitate at this location is disproportionately high, which has implications on functional impact. Superior capsule reconstruction, and, specifically, the anterior cable of the superior capsule, has been shown to assist in maintaining superior stability and a functional fulcrum of the glenohumeral joint, without overconstraining range of motion. Anterior cable reconstructions have been described for specific indications, including full-thickness tears of the supraspinatus and anterior one-half of the infraspinatus. Cord-like grafts, including long head biceps tendon autografts and semitendinosus allografts, can provide relative technical ease during surgery compared to sheet-like grafts for this indication. Side-to-side sutures between anterior cable reconstruction graft and posterosuperior capsule retension the native capsule to optimize its natural functional role. Accounting for abduction and rotation at the time of fixation and employing "loop-around" fixation sutures (no sutures through the graft), are critical concepts to consider in terms of kinematics and limiting graft failure. With both the biomechanically and clinically based literature demonstrating functionality with maintenance of the superior capsule (and specifically the anterior cable of the capsule), despite rotator cuff tendon insufficiency or irreparability, the anterior cable of the superior capsule should be prioritized when considering full-thickness rotator cuff tears that naturally involve both the capsular cable and the supraspinatus tendon cord. LEVEL OF EVIDENCE: Level V (expert opinion).

Biomechanical Assessment of a V-Shaped Semitendinosus Allograft Anterior Cable Reconstruction for Irreparable Rotator Cuff Tears.

PURPOSE: The purpose of this study was to biomechanically assess superior stability, subacromial contact pressures, and glenohumeral kinematics of a V-shaped anterior cable reconstruction with semitendinosus allograft (VST) in a massive rotator cuff tear (MCT) model. METHODS: Eight cadaveric shoulders (mean age, 66 years; range, 48 to 72 years) were tested with a custom testing system used to evaluate superior translation, subacromial contact pressure, and glenohumeral kinematics at 0°, 20°, and 40° glenohumeral abduction and 0°, 30°, 60°, and 90° of external rotation (ER). Conditions tested included (1) native state, (2) MCT (complete supraspinatus and ½ infraspinatus), a (3) VST. The VST was secured medially on the glenoid with 1 anchor and on the greater tuberosity with a double-row configuration using 4 anchors. RESULTS: The VST significantly decreased superior translation compared to the MCT at 0° and 20° glenohumeral abduction for 0°, 30°, and 60° humeral rotation and at 40° abduction and 0° degrees humeral rotation (P < .05). Superior translation following the VST remained significantly greater than the intact state at 0° abduction and 60° and 90° ER (P = .039 and 0.007, respectively) and 20° abduction and 30°, 60°, and 90° ER (P = .048, .003, and .004, respectively). The VST restored peak subacromial contact pressure to intact levels for all positions except 40° abduction and 60° ER. The VST did not statistically affect humeral head kinematics compared to the intact condition. CONCLUSIONS: In a biomechanical model, a VST anterior cable reconstruction partially restores superior stability and reduces peak subacromial contact pressure associated with an MCT, without affecting glenohumeral kinematics. The technique may be a consideration in the treatment of an irreparable MCT with isolated anterior cable disruption. CLINICAL RELEVANCE: The VST may provide an option for treatment of irreparable MCTs with anterior rotator cable disruption.

Editorial Commentary: Anterior Cable Reconstruction for the Shoulder Superior Capsule: Time for "Indication Rounds".

Anterior cable reconstruction (ACR) techniques for the superior capsule are multiple and varied. To optimize patient outcomes, technical considerations must be supported by basic science, both anatomically and biomechanically. ACR was designed to treat only partially repairable rotator cuff tendon tears, to provide a static support to a dynamic partial (and therefore "nonanatomic") repair, and to treat tears that could not be treated by transosseous-equivalent footprint-restoring "anatomic" repairs (both capsule and tendon repaired), but were also not so large as to necessitate superior capsule reconstruction. ACR allows restoration of posterosuperior capsular function with side-to-side repair sutures, and much of the biomechanical functionality comes from using whatever inherent native superior capsule is available. Cable reconstructions should be secured to normal attachment sites on the glenoid and greater tuberosity sulcus. Also, graft tension must be accounted for when considering humeral motion such as rotation and adduction. The indications for ACR need to be carefully considered and account for both anatomic and biomechanical rationales. In the face of new ACR techniques, the need to discern what is possible versus what procedure is indicated cannot be overlooked.

Anterior Cable Reconstruction of the Superior Capsule Using Semitendinosus Allograft for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis.

PURPOSE: To biomechanically assess translation, contact pressures, and range of motion for anterior cable reconstruction (ACR) using hamstring allograft for large to massive rotator cuff tears. METHODS: Eight cadaveric shoulders (mean age, 68 years) were tested with a custom testing system. Range of motion (ROM), superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction. Three conditions were tested: intact, stage III tear (supraspinatus + anterior half of infraspinatus), and stage III tear + allograft ACR (involving 2 supraglenoid anchors for semitendinosus tendon allograft fixation. Allograft ACR included loop-around fixation using 3 side-to-side sutures and an anchor at the articular margin to restore capsular anatomy along the anterior edge of the cuff defect. RESULTS: ACR with allograft for stage III tears showed significantly higher total ROM compared with intact at all angles (P ≤ .028). Augmentation significantly decreased superior translation for stage III tears at 0°, 30°, and 60° ER for both 0° and 20° abduction, and at 0° and 30° ER for 40° abduction (P ≤ .043). Augmentation for stage III tears significantly reduced overall subacromial contact pressure at 30° ER with 0° and 40° abduction, and at 60° ER with 0° and 20° abduction (P ≤ .016). CONCLUSION: Anterior cable reconstruction using cord-like allograft semitendinosus tendon can biomechanically improve superior migration and subacromial contact pressure (primarily in the lower combined abduction and rotation positions), without limiting range of motion for large rotator cuff tendon defects or tears. CLINICAL RELEVANCE: In patients with superior glenohumeral instability, using hamstring allograft for ACR may improve rotator cuff tendon defect longevity by providing basic static ligamentous support to the dynamic tendon while helping to limit superior migration, without restricting glenohumeral kinematics.

Biomechanical analysis of progressive rotator cuff tendon tears on superior stability of the shoulder.

BACKGROUND: The biomechanical relationship between irreparable rotator cuff tear size and glenohumeral joint stability in the setting of superiorly directed forces has not been characterized. The purpose of this study was to quantify kinematic alterations of the glenohumeral joint in response to superiorly directed forces in a progressive posterosuperior rotator cuff tear model. METHODS: Nine fresh-frozen cadaveric shoulders (mean age; 58 years) were tested with a custom shoulder testing system. Three conditions were tested: intact, stage II (supraspinatus) tear, stage III (supraspinatus + anterior half of infraspinatus) tear. At each condition, range of motion and humeral head positions were measured with a "balanced" loading condition, and with a superiorly directed force ("unbalanced loading condition"). At each of the 0°, 20°, and 40° of glenohumeral abduction positions, all measurements were made at 0°, 30°, 60°, and 90° of external rotation (ER). Two-way repeated measures analysis of variance with Tukey post hoc tests were performed for statistical analyses. RESULTS: With the balanced load, no significant change in superior humeral head position was observed in stage II tears. Stage III tears significantly changed the humeral head position superiorly at 30° and 60° ER at each abduction angle compared with the intact condition (P ≤ .028). With superiorly directed load, stage II and stage III tears both showed statistically significant increases in superior translation at all degrees of ER for all degrees of abduction (P ≤ .035), except stage II tears at 0° ER and 40° abduction (P = .185) compared with the intact condition. Stage II tears showed posterior translations with 30° and 60° ER, both at 20° and 40° of abduction. Stage III tears also showed posterior translations with 90° ER for all abduction angles (P ≤ .039). CONCLUSION: With superiorly directed loads, complete supraspinatus tendon tears created superior translations at all abduction angles, and posterior instability in the middle ranges of rotation for 20° and 40° of abduction. Larger tears involving the anterior half of the infraspinatus tendon caused significant superior and posterior translations within the middle ranges of ER for all abduction angles. In addition to superior instability, posterior translation should be considered when selecting or developing surgical techniques for large posterosuperior rotator cuff tears.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis.

PURPOSE: To assess an anterior cable reconstruction (ACR) using autologous proximal biceps tendon for large to massive rotator cuff tears. METHODS: Nine cadaveric shoulders (mean age, 58 years) were tested with a custom testing system. Range of motion, superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction. Five conditions were tested: intact, stage II tear (supraspinatus), stage II tear + ACR, stage III tear (supraspinatus + anterior half of infraspinatus), and stage III tear + ACR. ACR involved a biceps tendon tenotomy at the transverse humeral ligament, preserving its labral attachment. ACR included nonpenetrating suture-loop fixation using 2 side-to-side sutures and an anchor at the articular margin to restore anatomy and secure the tendon along the anterior edge of the cuff defect. ACR was performed in 20° glenohumeral abduction and 60° ER. RESULTS: ACR for both stage II and stage III showed significantly higher total range of motion compared with intact at all angles (P ≤ .001). ACR significantly decreased superior translation for stage II tears at 0°, 30°, and 60° ER for both 0° and 20° abduction (P ≤ .01) and for stage III tears at 0° and 30° ER for both 0° and 20° abduction (P ≤ .004). ACR for stage III tear significantly reduced peak subacromial contact pressure at 30° and 60° ER with 0° and 40° abduction and at 30° ER with 20° abduction (P ≤ .041). CONCLUSIONS: ACR using autologous biceps tendon biomechanically normalized superior migration and subacromial contact pressure, without limiting range of motion. CLINICAL RELEVANCE: ACR may improve rotator cuff tendon repair longevity by providing basic static ligamentous support to the dynamic tendon while helping to limit superior migration without restricting glenohumeral kinematics.

Knotless Transosseous-Equivalent Rotator Cuff Repair Improves Biomechanical Self-reinforcement Without Diminishing Footprint Contact Compared With Medial Knotted Repair.

PURPOSE: To assess the effect of medial-row knots on self-reinforcement and footprint contact characteristics for transosseous-equivalent repair compared with the same construct without knots. METHODS: In 8 fresh-frozen human shoulders, transosseous-equivalent repairs with and without medial-row mattress knots were performed in each specimen. A pressure sensor was fixed at the tendon-footprint interface for all repairs. Parameters measured included footprint contact area, force, and pressure. The supraspinatus tendon was loaded sequentially from 0 to 60 N at 0° and 30° of abduction. RESULTS: Both repairs provided a linear progression (slope) of footprint force and pressure as increasing tendon loads were applied. However, the knotless repair had a significantly higher progression ("self-reinforcement" effect) than the knotted repair at both abduction angles (P = .006 at 0° and P = .021 at 30°). The addition of medial-row knots did not significantly change the footprint contact area (in square millimeters), contact force (in newtons), contact pressure (in kilopascals), or peak pressure (in kilopascals) at each load tested, as well as at both abduction angles. For a given repair, only the knotless repair had significant decreases in contact area, contact force, contact pressure, and peak pressure with increasing abduction angles from 0° to 30° (P = .004 and P = .048). CONCLUSIONS: Knotless transosseous-equivalent repair shows an improved self-reinforcement effect, without diminishing footprint contact, compared with the same repair with medial knots. Although knotless repair itself can show diminished footprint contact with abduction, medial knots show an adverse biomechanical effect by inhibiting self-reinforcement, without improving contact characteristics compared with knotless repair at each abduction angle tested. Clinical outcomes with specific indications, on the basis of these findings, require further investigation. CLINICAL RELEVANCE: This study biomechanically helps to validate studies that have shown clinical success with knotless transosseous-equivalent repair. The inhibition of self-reinforcement may provide a quantified biomechanical rationale for medial tear patterns seen with knotted repairs.

Editorial Commentary: Can Passive Muscle Stiffness in a Cadaveric Study Be Clinically Related to Using Knotted Versus Knotless Rotator Cuff Repair?

Is a biomechanical cadaveric study to assess the effect of rotator cuff tear size and repair technique on supraspinatus muscle stiffness clinically relevant? A study in this issue compared double-row and knotless transosseous-equivalent repairs, but notably, muscle loading was not simulated. Results showed that the knotless transosseous-equivalent repair for larger tears demonstrated a more uniform stiffness distribution across the supraspinatus muscle compared with the double-row repair. However, given the inherently asymmetrical functional anatomy and morphology of the supraspinatus tendon-muscle unit, when muscle tone exists, the effect of the repair technique on muscle stiffness in vivo may not be determined based on the findings of this study.

Biomechanical effects of a 2 suture-pass medial inter-implant mattress on transosseous-equivalent rotator cuff repair and considerations for a "technical efficiency ratio".

BACKGROUND: Rotator cuff repair involving fewer tendon suture passes without compromising biomechanical performance would represent a technical advancement. An inter-implant "medial pulley-mattress" transosseous-equivalent (MP-TOE) repair requiring fewer tendon suture-passes was hypothesized to provide equivalent biomechanical characteristics compared to the control. METHODS: In 6 human cadaveric shoulders, a transosseous-equivalent (TOE) repair (control) was performed utilizing 2 separate medial mattresses resulting in 4 tendon-bridging sutures. In 6 matched-pairs, 2 single-loaded anchors were used to create a medial inter-implant mattress construct (all sutures shuttled in 1 tendon pass per anchor)-after knot-tying, the same tendon-bridging pattern as the control was created. A materials testing machine cyclically loaded each repair from 10-180 N for 30 cycles; each repair subsequently underwent failure testing. Gap and strain were measured with a video digitizing system. A "technical efficiency ratio" (TER) was defined as: (#knots + #suture passes + #suture limbs)/#fixation points. RESULTS: Cyclic and failure testing demonstrated no significant differences between constructs. Gap formation at cycle 30 was 5.3 ± 0.8 mm (TOE) and 5.0 ± 0.3 mm (MP-TOE) (P = .62). Cycle 30 anterior strain values were -16.0 ± 7.3% (TOE) and -15.8 ± 6.6% (MP-TOE) (P = .99). Yield loads were 208.7 ± 2.7 N (TOE) and 204.0 ± 1.3 N (MP-TOE) (P = .17). Mode of failure demonstrated less tendon cut-out with the MP-TOE repair. The MP-TOE repair has a TER of 2.0 vs 2.5 for the control. CONCLUSION: The MP-TOE repair requiring fewer tendon suture passes, yet creating an additional inter-implant mattress configuration, is biomechanically equivalent to the original TOE technique, and may limit failure with improved medial load-sharing capacity. A TER may help quantify technical ease and help standardize comparisons between repair techniques.

Does transosseous-equivalent rotator cuff repair biomechanically provide a "self-reinforcement" effect compared with single-row repair?

BACKGROUND: Transosseous-equivalent (TOE) rotator cuff repair has been theorized to be "self-reinforcing" against potentially destructive and increasing tendon loads. The goal of this study was to biomechanically verify and characterize the effect of increasing tendon load on frictional resistance over a repaired footprint for single-row (SR) and TOE repair techniques. METHODS: In 10 fresh frozen human shoulders, TOE and SR supraspinatus tendon repairs were performed in each specimen. For all repairs, a pressure sensor was secured at the tendon-footprint interface. The supraspinatus tendon was loaded with 0, 20, 40, 60, and 80 N at 0° and 30° abduction. Paired t tests and multivariate regression analyses were used for comparisons. RESULTS: The SR repair had significant increases in footprint contact force, area, and pressure between each and all tendon-loading conditions (P < .05). The TOE repair similarly demonstrated increases in footprint contact force with increasing tendon load (P < .05). Comparing between repairs, TOE repair had more footprint contact force, area, pressure, and peak pressure at each load for both abduction angles (P < .05). With increasing load, the TOE repair had a significantly higher progression (slope) of footprint force and pressure compared with the SR repair. CONCLUSIONS: Self-reinforcing capacity in rotator cuff repair has been biomechanically characterized and verified. The TOE repair, with tendon-bridging sutures fixed medially and spanning the footprint, provides disproportionately more progressive footprint frictional resistance with increasing tendon loads compared with the SR repair secured over isolated fixation points. This self-reinforcing effect could help sustain structural integrity and potentially improve healing biology.

Biomechanical validation of rotator cuff repair techniques and considerations for a "technical efficiency ratio".

Biomechanical studies are commonly used to validate new or modified rotator cuff repair techniques. Additional knots, more tendon suture passes, and obligatory suture management requirements are often the "cost" for improved biomechanical results. This cost can amount to increased technical difficulty and surgical times. However, technical ease or difficulty as a measurable variable has not been quantified. A basic measure for technical ease would allow surgeons the ability to objectively assess and compare rotator cuff repair practicality and potentially help in the design of future studies to standardize repair techniques alongside biomechanical measures. A proposed rotator cuff repair "technical efficiency ratio" is defined as follows: (No. of knots + No. of tendon suture passes + No. of suture limbs)/No. of pilot holes created. This can give a measure of "work" or utility achieved per fixation point created for a particular type of repair (e.g., single or double row), with a smaller number representing relatively more efficiency per anchor or fixation point used. If repairs validated in the laboratory are too cumbersome to perform in vivo from a practical standpoint, technical ease should be a prerequisite measure, and the success of a repair technique should not necessarily be based on biomechanics alone.

Rotator cuff tendon repair morphology comparing 2 single-anchor repair techniques.

PURPOSE: To compare the effect of 2 common rotator cuff repair techniques, for smaller tears limited to the use of a single anchor, on tendon morphology in relation to the footprint. METHODS: Six matched pairs of human shoulders were dissected, and a standardized 10-mm supraspinatus tendon tear was created. Two single-anchor repairs were performed: simple repair with the anchor on the footprint or inverted-mattress repair with the anchor 1 cm distal-lateral to the footprint. The repaired specimens were frozen in situ with liquid nitrogen. Coronal cross sections through the intact and repaired tendon were made. A digitizer was used to measure variables including tendon area and radius of tendon curvature. RESULTS: Comparing between repairs, we found significantly more gap formation for the simple repair at the repair cross section (3.67 ± 0.32 mm v 0.68 ± 0.10 mm, P = .00050). The simple repair had less tendon area (38.28 ± 2.50 mm(2)v 58.65 ± 4.06 mm(2), P = .0036) and a smaller radius of curvature (8.47 ± 1.39 mm v 32.51 ± 3.94 mm, P = .0046). For the simple repair, there was significantly more gap formation, less tendon area, and a smaller radius of tendon curvature for all repair cross sections compared with the intact cross sections (P < .05). For the inverted-mattress repair, there was more gap formation compared with the intact condition (P < .05), although it was less than 1 mm on average; for tendon area, radius of curvature, and tendon height, the cross section centered on the repair showed no differences compared with the intact control. CONCLUSIONS: For rotator cuff tears that are 10 mm or smaller and limited to the use of a single anchor, using a distal-lateral anchor position with tape-type suture can provide better maintenance of native tendon morphology and footprint dimensions when compared with repair that uses standard sutures and places the anchor on the footprint. CLINICAL RELEVANCE: For smaller tears, the inverted-mattress repair described in this article may provide a relatively improved healing environment compared with a simple repair on the footprint, potentially optimizing the prevention of early tear progression.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects.

Tears of the rotator cuff tendons can occur that do not allow anatomic footprint restoration yet may not be large enough to require a superior capsular reconstruction technique. Typically, these intermediate-sized tears are addressed with a medialized repair or partial repair technique. A partially repaired rotator cuff tendon, however, can lead to a high retear rate, as the repaired tendon is required to serve as both a dynamic tendon and a static ligamentous stabilizer. One potential static support, as a nearby autologous graft donor, is the proximal long head biceps tendon. The purpose of this Technical Note is to describe a surgical technique for an anterior cable reconstruction using the proximal biceps tendon for large rotator cuff defects.

Part I: Footprint contact characteristics for a transosseous-equivalent rotator cuff repair technique compared with a double-row repair technique.

Rotator cuff repair via transosseous tunnels can improve footprint contact area and pressure when compared with suture anchor techniques. A double-row technique has been used clinically to improve footprint coverage by a repaired tendon. We hypothesized that a transosseous-equivalent rotator cuff repair via tendon suture bridges would demonstrate improved pressurized contact between the tendon and tuberosity when compared with a double-row technique. In 6 fresh-frozen human shoulders, a transosseous-equivalent rotator cuff repair was performed: a suture limb from each of 2 medial anchors was bridged over the tendon and fixed laterally with an interference screw (4 suture bridges). In 6 of the contralateral specimens, two types of repair were performed randomly in each specimen: (1) a double-row repair and (2) a transosseous-equivalent repair with a single screw (2 suture bridges). For all repairs, pressure-sensitive film was placed at the tendon-footprint interface, and software was used to obtain measurements. The mean pressurized contact area between the tendon and insertion was significantly greater for the 4-suture bridge technique (124.2 +/- 16.3 mm2, 77.6% footprint) compared with both the double-row (63.3 +/- 28.5 mm2, 39.6% footprint) and 2-suture bridge (99.7 +/- 22.0 mm2, 62.3% footprint) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was greater for the 4-suture bridge technique (0.27 +/- 0.04 MPa) than for the double-row technique (0.19 +/- 0.01 MPa) (P = .002). The transosseous-equivalent rotator cuff repair technique can improve pressurized contact area and mean pressure between the tendon and footprint when compared with a double-row technique. A transosseous-equivalent technique, using suture bridges, may help optimize the healing biology at a repaired rotator cuff insertion.

Part II: Biomechanical assessment for a footprint-restoring transosseous-equivalent rotator cuff repair technique compared with a double-row repair technique.

We hypothesized that a transosseous-equivalent repair would demonstrate improved tensile strength and gap formation between the tendon and tuberosity when compared with a double-row technique. In 6 fresh-frozen human shoulders, a transosseous-equivalent rotator cuff repair was performed: a suture limb from each of two medial anchors was bridged over the tendon and fixed laterally with an interference screw. In 6 contralateral matched-pair specimens, a double-row repair was performed. For all repairs, a materials testing machine was used to load each repair cyclically from 10 N to 180 N for 30 cycles; each repair underwent tensile testing to measure failure loads at a deformation rate of 1 mm/sec. Gap formation between the tendon edge and insertion was measured with a video digitizing system. The mean ultimate load to failure was significantly greater for the transosseous-equivalent technique (443.0 +/- 87.8 N) compared with the double-row technique (299.2 +/- 52.5 N) (P = .043). Gap formation during cyclic loading was not significantly different between the transosseous-equivalent and double-row techniques, with mean values of 3.74 +/- 1.51 mm and 3.79 +/- 0.68 mm, respectively (P = .95). Stiffness for all cycles was not statistically different between the two constructs (P > .40). The transosseous-equivalent rotator cuff repair technique improves ultimate failure loads when compared with a double-row technique. Gap formation is similar for both techniques. A transosseous-equivalent repair helps restore footprint dimensions and provides a stronger repair than the double-row technique, which may help optimize healing biology.

False magnetic resonance imaging persistence of a biodegradable anterior cruciate ligament interference screw with chronic inflammation after 4 years in vivo.

Surgeons should be aware that the degradation kinetics of biodegradable implants likely influence the rate of osseous integration, and depend on numerous factors such as polymer weight, crystallinity, and stereocopolymer ratio. We present a case of inflammatory reaction at a polylactide tibial interference screw site more than 4 years after primary anterior cruciate ligament (ACL) reconstruction. This inflammation was presumptively treated as an infection with surgical irrigation and debridement. Preoperatively, the screw was clearly delineated by magnetic resonance imaging (MRI), yet was grossly absent at surgery. Postoperative MRI confirmed thorough debridement and complete absence of the screw. This report shows that not only can a late inflammatory reaction occur, after up to 4 years in vivo, but that the MRI may show a persistent screw despite significant biodegradation. False MRI-persistent screws should be considered when critically reviewing studies that use MRI in the methods for evaluating biodegradable implants. More importantly, false MRI-persistent screws may have significant ramifications when planning revision surgery after primary ACL reconstruction having used interference screws that can degrade over several years.

"Transosseous-equivalent" rotator cuff repair technique.

In order to optimize healing biology at a repaired rotator cuff footprint, we have developed a "transosseous-equivalent" rotator cuff repair that can be performed arthroscopically. What the arthroscopically repaired tendon experiences is "equivalent" to what is experienced with a traditional open suture-bridge technique. This repair maximizes the utility of a single-row repair technique by preserving the suture limbs of the medial single-row and bridging these sutures over the footprint insertion with distal-lateral interference screw suture fixation; the medial row uses a mattress suture configuration. The geometry of the construct compresses the tendon, optimizing tendon-to-tuberosity contact dimensions, while providing strength sufficient to withstand immediate postoperative rehabilitation.

Tendon-to-bone pressure distributions at a repaired rotator cuff footprint using transosseous suture and suture anchor fixation techniques.

BACKGROUND: Interface contact pressure between the tendon and bone has been shown to influence healing. This study evaluates the interface pressure of the rotator cuff tendon to the greater tuberosity for different rotator cuff repair techniques. HYPOTHESIS: The transosseous tunnel rotator cuff repair technique provides larger pressure distributions over a defined insertion footprint than do suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Simulated rotator cuff tears over a 1 x 2-cm infraspinatus insertion footprint were created in 25 bovine shoulders. A transosseous tunnel simple suture technique (n = 8), suture anchor simple technique (n = 9), and suture anchor mattress technique (n = 8) were used for repair. Pressurized contact areas and mean pressures of the repaired tendon against the tuberosity were determined using pressure-sensitive film placed between the tendon and the tuberosity. RESULTS: The mean contact area between the tendon and tuberosity insertion footprint was significantly greater for the transosseous technique (67.7 +/- 5.8 mm(2)) compared with the suture anchor simple (34.1 +/- 9.4 mm(2)) and suture anchor mattress (26.0 +/- 5.3 mm(2)) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was also greater for the transosseous technique (0.32 +/- 0.05 MPa) compared with the suture anchor simple (0.26 +/- 0.04 MPa) and suture anchor mattress (0.24 +/- 0.02 MPa) techniques (P < .05). CONCLUSION: The transosseous tunnel rotator cuff repair technique creates significantly more contact and greater overall pressure distribution over a defined footprint when compared with suture anchor techniques. CLINICAL RELEVANCE: Stronger and faster rotator cuff healing may be expected when beneficial pressure distributions exist between the repaired rotator cuff and its insertion footprint. Tendon-to-tuberosity pressure and contact characteristics should be considered in the development of improved open and arthroscopic rotator cuff repair techniques.