Anatomic Acromioclavicular Joint Reconstruction with and without Acromioclavicular Ligament Reconstruction: A Comparative Biomechanical Study.

Background: The purpose of this study was to determine if adding a reconstructed superior acromioclavicular (AC) joint ligament adds significant biomechanical stability to the AC joint over anatomic coracoclavicular (CC) ligament reconstruction alone. Methods: Fourteen cadaver shoulders were used for the comparison of biomechanical stability among the anatomic CC ligament reconstruction alone, CC and AC ligament reconstruction, and the intact groups by measuring the displacement under cyclic loads. A load to failure test was then performed in the vertical direction at a loading rate of 2 mm /sec to determine surgical-repair joints' tolerance to the maximum failure load. Results: The average peak-to-peak displacement induced by cyclic load in the sagittal axis and vertical axis direction was not significantly different between CC ligament reconstruction, CC and AC ligament reconstruction, and intact groups. The maximum failure load for the CC reconstruction (224.9 ± 91.8 N (Mean ± SEM)) was lower than CC/AC reconstruction groups (326.2 ± 123.3 N). The CC/AC reconstruction group failed at a significantly higher load (t test, p = 0.016) than the CC reconstruction group. Conclusion: CC/AC reconstruction surgical technique yielded a better shoulder stability than CC ligament alone reconstruction that may better maintain reduction of the AC joint.Level of Evidence: Level II.

Editorial Commentary: Periarticular and Intra-Articular Injections May Do the Right Thing for Patients' Pain but May Be the Wrong Thing for Their Articular Cartilage: Be Careful.

Periarticular and intra-articular injections are regularly used by orthopaedic surgeons both in the clinic and operative setting. These injections include the use of local anesthetics, nonsteroidal anti-inflammatories, steroidal anti-inflammatories, and other classes of pharmaceuticals. Local anesthetics can be injected alone or in conjunction with other pharmaceuticals to maximize pain control and to minimize narcotic use as part of a multimodal pain control algorithm. Use of intra-articular local anesthetics has been shown to improve postoperative pain scores and reduce intravenous and oral narcotic consumption and narcotic-related side effects, such as constipation, sedation, depression, respiratory depression, and long-term abuse potential. However, there have been reports of chondrolysis and other side effects from these injections. In general, it can be said that lidocaine is more chondrotoxic than bupivacaine and that methylprednisolone is more chondrotoxic when combined with either lidocaine or bupivacaine. Ropivacaine with steroid maybe less chondrotoxic, but this has yet to be established. It has been shown that ropivacaine with steroids may be toxic to chondrocytes as well as bovine tenocytes. In addition, it can be generalized that longer exposures, such as an indwelling, intra-articular catheter, are more chondrotoxic than shorter exposures, such as an intra-articular injection. Greater concentrations of lidocaine and bupivacaine (i.e., 1% vs 2% and 0.25% vs 0.5%, respectively) are more toxic to chondrocytes. Cellular morphine studies have resulted in conflicting reports of whether or not it is chondrotoxic. Both ketorolac and acetaminophen have been shown to decrease postoperative pain, but ketorolac also has been shown to be chondrotoxic in a human chondrocyte model. Doing the right thing for our patients' pain may be the wrong thing for their articular cartilage. Expansion of indications for these injections should be approached with caution.

Physeal-sparing posteromedial portal approach reduced distance between guide pin and neurovascular structures.

PURPOSE: To compare a femoral physeal sparing anterior cruciate ligament (ACL) reconstruction technique utilizing a posteromedial portal to traditional transphyseal techniques with regards to anatomic tunnel positioning and proximity to important neurovascular structures. METHODS: Eight cadaveric knees were obtained for the study. Femoral tunnel guide pins were placed utilizing four different techniques: accessory anterior medial portal, posteromedial portal, trans-tibial, and figure-4 methods. The knees were then dissected and the following measurements taken: distance of each pin to the saphenous and peroneal nerve, popliteus tendon, neurovascular bundle, femoral ACL footprint and articular cartilage, and the angle of the guide pin entering the lateral femoral condyle. Fluoroscopic imaging was taken to determine the disruption of the physeal scar. RESULTS: Posteromedial portal guide pin was significantly closer to the neurovascular bundle, popliteal tendon and saphenous nerve when compared to the other 3 techniques, but was further from the peroneal nerve. It also had the smallest distance from the anatomic footprint of the ACL, and the largest angle to the lateral femoral condyle. The posteromedial portal guide pin had similar distance from the articular cartilage as the accessory anterior medial portal and figure-4 guide pin, with the trans-tibial guide pin being the farthest. The posteromedial portal guide pin failed to disrupt the physeal scar in all specimens, while the other three techniques consistently violated the physeal scar. CONCLUSION: The posteromedial portal technique offers an appropriate method for anatomic ACL reconstruction while protecting the distal femoral physis from injury. Care needs to be taken with this technique as it comes in closer proximity to some of the important neurovascular structures. This study indicates that posteromedial portal technique is a less technically challenging approach for physeal-sparing ACL repair with special attention required for the protection of neurovascular bundle from potential injury.

Acetaminophen, bupivacaine, Duramorph, and Toradol: A comparison of chondrocyte viability and gene expression changes in osteoarthritic human chondrocytes.

BACKGROUND: A multitude of chemical agents are currently used intra-articularly to decrease pain after orthopaedic procedures including total knee arthroplasty. However, the possible deleterious effects of these injectable chemicals on chondrocyte viability have not been weighed against their potential benefits. Using a human osteoarthritic chondrocyte model, the purpose of this study was to assess the potential for cartilage damage caused by bupivacaine, Toradol, Duramorph, and acetaminophen from surgical local anesthesia. METHODS: Human distal femur and proximal tibia cross sections were obtained during total knee arthroplasty and divided into control group and experimental groups treated by bupivacaine, Toradol, Duramorph, and acetaminophen respectively. Chondrocytes obtained from enzymatically digested cartilage were cultured using a 3D alginate bead culture method to ensure lower rates of dedifferentiation. Chondrocyte bead cultures were exposed to the study chemicals. The gene expression and chondrocyte viability were measured by RT-PCR and flow cytometry, respectively. RESULTS: Compared with untreated group bupivacaine treatment led to the greatest cellular apoptosis with 30.5 ± 11% dead cells (P = 0.000). Duramorph and acetaminophen did not result in a significant increase in cell death. Bupivacaine treatment led to an increase in Caspase 3 gene expression (P = 0.000) as well as the acetaminophen treatment (P = 0.001) when compared to control. CONCLUSION: Our data demonstrated that Duramorph and Toradol were not cytotoxic to human chondrocytes and may be better alternatives to the frequently used and more cytotoxic bupivacaine. Acetaminophen did not result in increased cell death; however, it did show increased caspase 3 gene expression and caution should be considered.

Shoulder muscle activation pattern recognition based on sEMG and machine learning algorithms.

BACKGROUND AND OBJECTIVE: Surface electromyography (sEMG) has been used for robotic rehabilitation engineering for volitional control of hand prostheses or elbow exoskeleton, however, using sEMG for volitional control of an upper limb exoskeleton has not been perfectly developed. The long-term goal of our study is to process shoulder muscle bio-electrical signals for rehabilitative robotic assistive device motion control. The purposes of this study included: 1) to test the feasibility of machine learning algorithms in shoulder motion pattern recognition using sEMG signals from shoulder and upper limb muscles, 2) to investigate the influence of motion speed, individual variability, EMG recording device, and the amount of EMG datasets on the shoulder motion pattern recognition accuracy. METHODS: A novel convolutional neural network (CNN) structure was constructed to process EMG signals from 12 muscles for the pattern recognition of upper arm motions including resting, drinking, backward-forward motion, and abduction motion. The accuracy of the CNN models for pattern recognition under different motion speeds, among individuals, and by EMG recording devices was statistically analyzed using ANOVA, GLM Univariate analysis, and Chi-square tests. The influence of EMG dataset number used for CNN model training on recognition accuracy was studied by gradually increasing dataset number until the highest accuracy was obtained. RESULTS: Results showed that the accuracy of the normal speed CNN model in motion pattern recognition was 97.57% for normal speed motions and 97.07% for fast speed motions. The accuracy of the cross-subjects CNN model in motion pattern recognition was 79.64%. The accuracy of the cross-device CNN model in motion pattern recognition was 88.93% for normal speed motion and 80.87% for mixed speed. There was a statistical difference in pattern recognition accuracy between different CNN models. CONCLUSION: The EMG signals of shoulder and upper arm muscles from the upper limb motions can be processed using CNN algorithms to recognize the identical motions of the upper limb including drinking, forward/backward, abduction, and resting. A simple CNN model trained by EMG datasets of a designated motion speed accurately detected the motion patterns of the same motion speed, yielding the highest accuracy compared with other mixed CNN models for various speeds of motion pattern recognition. Increase of the number of EMG datasets for CNN model training improved the pattern recognition accuracy.

Processing Surface EMG Signals for Exoskeleton Motion Control.

The surface electromyography (sEMG) signal has been used for volitional control of robotic assistive devices. There are still challenges in improving system performance accuracy and signal processing to remove systematic noise. This study presents procedures and a pilot validation of the EMG-driven speed-control of exoskeleton and integrated treadmill with a goal to provide better interaction between a user and the system. The gait cycle duration (GCD) was extracted from sEMG signals using the autocorrelation algorithm and Bayesian fusion algorithm. GCDs of various walking speeds were then programmed to control the motion speed of exoskeleton robotic system. The performance and efficiency of this sEMG-controlled robotic assistive ambulation system was tested and validated among 6 healthy volunteers. The results demonstrated that the autocorrelation algorithm extracted the GCD from individual muscle contraction. The GCDs of individual muscles had variability between different walking steps under a designated walking speed. Bayesian fusion algorithms processed the GCDs of multiple muscles yielding a final GCD with the least variance. The fused GCD effectively controlled the motion speeds of exoskeleton and treadmill. The higher amplitude of EMG signals with shorter GCD was found during a faster walking speed. The algorithms using fused GCDs and gait stride length yielded trajectory joint motion tracks in a shape of sine curve waveform. The joint angles of the exoskeleton measured by a decoder mounted on the hip turned out to be in sine waveforms. The hip joint motion track of the exoskeleton matched the angles projected by trajectory curve generated by computer algorithms based on the fused GCDs with high agreement. The EMG-driven speed-control provided the human-machine inter-limb coordination mechanisms for an intuitive speed control of the exoskeleton-treadmill system at the user's intents. Potentially the whole system can be used for gait rehabilitation of incomplete spinal cord hemispheric stroke patients as goal-directed and task-oriented training tool.

The all-inside all-suture technique demonstrated better biomechanical behaviors in meniscus radial tear repair.

PURPOSE: The purpose of this study was to evaluate the effectiveness of three constructs and techniques for repair of radial tears of the meniscus. METHODS: Thirty fresh frozen porcine menisci were divided equally into three groups consisting of (1) inside-out repair group, (2) a commonly used all-inside suture with anchor hybrid repair construct (AISAH) (Meniscal Cinch™), and (3) an all-inside all-suture repair construct (AIAS) (Knee Scorpion™). Radial tears were created and repaired and then the menisci were secured to the materials testing machine. Both cyclic loading and load-to-failure testing were performed. The displacement, stiffness, response to cyclic loading, and mode of failure were recorded and analyzed statistically. RESULTS: The displacement after cyclic loading (DACL) of the Cinch repair construct group was significantly higher than that of the inside-out repair construct group (p = 0.000) and AIAS repair construct (p = 0.000). There was not a statistical difference of DACL between inside-out and AIAS groups (n.s.). The inside-out construct failed at a significantly higher load than the AISAH repair construct (p = 0.000) and AIAS construct (p = 0.006). The AIAS construct failed at a significantly higher load than the AISAH repair construct (p = 0.009). The AIAS had a higher stiffness than AISAH (p = 0.047). The AIAS had a higher load at 3 mm protrusion than AISAH (p = 0.034). CONCLUSION: The AIAS repair construct had better biomechanical behaviors than AISAH construct and inside-out repair technique. Inside-out sutures and AIAS repair construct had similar biomechanical responses to cyclic loading. The AIAS can be used for meniscus tear surgical repair with less damage to peri-meniscus tissues.

Analysis of Non-Game Injuries in Major League Baseball.

BACKGROUND: Numerous studies have investigated injuries and treatments in the baseball athlete. The majority of these studies have focused on the throwing shoulder and elbow. However, more recent literature is reporting injuries to other regions in this cohort, including the knee, head, hip, and hamstring. PURPOSE/HYPOTHESIS: The purpose of the current study was to determine the number and type of injuries in Major League Baseball (MLB) and Minor League Baseball (MiLB) players that do not occur during the actual game but are related to baseball participation. Our hypothesis was that there would be a substantial number of injuries that occurred in professional baseball players during non-game situations. STUDY DESIGN: Descriptive epidemiological study. METHODS: Deidentified, anonymous data were collected from the 2011 through 2016 seasons from the MLB Health and Injury Tracking System (HITS) medical record database. All injuries that were identified as a primary diagnosis and resulted in at least 1 day out of play from both MLB and MiLB were examined. Injuries were categorized as occurring during the game ("game" injuries) or not during the game. A "non-game" injury was defined as occurring at any time other than during the scheduled game from the first to last pitch. RESULTS: There were 51,548 total injuries in MLB and MiLB players from 2011 to 2016, almost 40% of which were attributed to non-game-related injuries (n = 19,201; 37.2%). The remainder occurred during a game (n = 32,347; 62.8%). A significantly greater percentage of non-game injuries were season ending (10.8%) compared with the percentage of game-related season-ending injuries (8.4%) (P < .0001). Pitchers had significantly more non-game-related injuries than game-related injuries (P < .0001). CONCLUSION: A large number of injuries occur in professional baseball outside of actual games. MiLB players, specifically pitchers, are particularly at risk for these types of injuries. It is feasible that the overall injury rate in professional baseball players could be reduced by analyzing these injuries in more detail to develop prevention strategies.

Radial Tears of the Lateral Meniscus-Two Novel Repair Techniques: A Biomechanical Study.

BACKGROUND: A common treatment for radial tears of the meniscus has historically been partial meniscectomy. Owing to the poor outcomes associated with partial meniscectomy, repair of the meniscus is an important treatment option. It is important to evaluate different repair techniques for radial tears of the meniscus. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate 2 novel techniques to repair radial tears of the lateral meniscus. The 2 techniques were compared biomechanically with the cross-suture method with an inside-out technique. The authors hypothesized that novel repair techniques would result in less displacement after cyclic loading, increased load required to displace the repair 3 mm, greater load to failure, decreased displacement at load to failure, and increased stiffness of the repair, resulting in a construct that more closely re-creates the function of the intact meniscus. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 36 fresh-frozen cadaveric tibial plateaus containing intact menisci were obtained. The menisci were divided into 3 groups (n = 12 in each group), and each meniscus was repaired simulating an inside-out technique. The 3 repairs completed were the hashtag, crosstag, and cross-suture techniques. Radial tears were created at the midbody of the lateral meniscus and repaired via the 3 techniques. The repaired menisci were attached to an axial loading machine and tested for cyclic and failure loading. RESULTS: After cyclic loading, the cross-suture repair displaced 4.78 ± 1.65 mm; the hashtag, 2.42 ± 1.13 mm; and the crosstag, 3.13 ± 1.77 mm. The hashtag and cross-tag repairs both resulted in significantly less displacement (P = .003 and .024, respectively) as compared with the cross-suture repair. The cross-suture technique had a load to failure of 81.43 ± 14.31 N; the hashtag, 86.08 ± 23.58 N; and the crosstag, 62.50 ± 12.15 N. The cross-suture and hashtag repairs both resulted in a greater load to failure when compared with the crosstag (P = .009 and .009, respectively). There was no difference comparing the load required to displace the cross-suture technique 3 mm versus the hashtag or crosstag technique (P = .564 and .094, respectively). However, when compared with the crosstag technique, the hashtag technique required a significantly greater load to displace the repair 3 mm (P = .015). CONCLUSION: This study introduced 2 novel repair techniques-hashtag and crosstag-that did not demonstrate superiority in terms of load to failure or stiffness, but both repairs were statistically superior to the cross-suture repair in terms of displacement after cyclic loading. Considerations that may influence the validity of these techniques include cost, surgical time, and increased technical demand. CLINICAL RELEVANCE: Radial tears of the meniscus are difficult to repair. Further research into more stable constructs is necessary.

Proximity of Lateral Critical Structures to the All-Epiphyseal Outside-In Femoral Tunnels in Pediatric Anterior Cruciate Ligament Reconstruction.

PURPOSE: To describe the proximity of the lateral critical structures (peroneal nerve [PN], popliteus tendon [PT], lateral collateral ligament [LCL], and articular cartilage [AC]) to the femoral tunnel for outside-in all-epiphyseal anterior cruciate ligament (ACL) reconstruction in reference to knee flexion angle. METHODS: All-epiphyseal ACL reconstructions were performed in 12 human cadaveric knees using arthroscopy and outside-in drilling for anatomic femoral tunnel placement that was ensured by identifying the center of the total ACL footprint. Fluoroscopy was used to confirm tunnel position and reconstructions were performed with quadrupled semitendinosus and gracilis autograft with Xtendobutton (Smith & Nephew, Andover, MA) fixation on the femoral side. After reconstruction, the lateral side of the knee was dissected and the LCL, PT, distal and posterior AC, and the PN were identified. The distances of these structures from the center of the exiting femoral tunnel were then measured using a digital caliper at 0°, 30°, 60°, 90°, and 120° of knee flexion. Any gross damage to these structures caused by the femoral drilling was also noted. Data were compiled and the mean and standard deviations (SD) of the distances from the pin to the structures of interest were calculated. The normality of the data at each flexion angle was assessed using Shapiro-Wilk tests (P > .05), and the relationship between flexion angle and average distance was evaluated using repeated measures analysis of variance (P < .05). Any significant relationships were then evaluated using paired t-tests (P < .05) with a Benjamini-Hochberg adjustment for each possible pair of flexion angles. Averages, SD, and P values are reported. A post hoc power analysis was performed. RESULTS: The violation of the LCL was noted in 3 specimens and that of the PT in 1 specimen as a result of femoral tunnel drilling at flexion angles ranging from 90° to 120°. The distance between the PT and the femoral tunnel also decreased significantly (P < .001) with knee flexion with average distances to the center of 8.07 mm at 0°, 7.75 mm at 30°, 6.33 mm at 60°, 4.12 mm at 90°, and 1.89 mm at 120°. The mean ± SD for distances from the femoral tunnel to the center of the PT at 0° was 8.07 ± 7.15, at 30° 7.75 ± 6.66, at 60° 6.33 ± 6.79, at 90° 4.12 ± 5.71, and at 120° 1.89 ± 5.56. As the knee was progressively flexed, the distance between the LCL and the femoral tunnel decreased significantly (P < .001) with an average distance of 6.52 mm at 0°, 6.26 mm at 30°, 4.23 mm at 60°, 2.38 mm at 90°, and 0.4 mm at 120°. The mean ± SD for distances from the femoral tunnel to the center of the LCL at 0° was 6.52 ± 5.93, at 30° 6.26 ± 7.32, at 60° 4.23 ± 7.82, 90° 2.38 ± 7.31, and at 120° 0.4 ± 7.01. The PN was remote from the femoral tunnel at all flexion angles with a mean distance of 42.83 to 59.22 mm. The PN to guide pin distance increased significantly with progressive knee flexion (P < .001). The AC was not damaged in all specimens. CONCLUSIONS: The LCL and PT are at significant risk during percutaneous femoral drilling for all-epiphyseal anatomic ACL reconstruction using an outside-in technique. This risk was maximized at 120° flexion and minimized in full extension. These findings suggest that the optimal position for femoral drilling in all-epiphyseal ACL reconstruction is full or near-full extension of the knee that can be accomplished by placing the knee in 30° of flexion (after using fluoroscopic guidance to pass the guide pin past the lateral critical structures) to visualize the footprint of the ACL. CLINICAL RELEVANCE: Information garnered from this study may help clinicians better understand the risk to the lateral critical structures when an outside-in femoral tunnel is not drilled in the appropriate degree of knee flexion.

The Interaction of Intramuscular Ketorolac (Toradol) and Concussion in a Rat Model.

The purpose of this study was to examine the interaction of a single dose of Toradol and head impact in an in vivo rat model for sport-related concussion using a validated rat concussion model. Thirty-five Sprague-Dawley rats were placed into one of four groups: (1) Control, (2) Impact Only, (3) Toradol Only, (4) Impact and Toradol. Animals in the impact groups were subjected to a single head impact. Animals in the Toradol group received a single intramuscular injection of Toradol prior to impact. We examined magnetic resonance imaging, serum S100-B and cognitive function using a Morris Water Maze. In the control group, latency decreased significantly from day 0 (74.9 s) to 24 h (57.4 s) after anesthesia. There was no statistically significant difference between time zero and 24 h after impact in the Impact only or Impact and Toradol group. Our findings indicate that there were no differences between cognitive ability, MRI findings or S100B in rats that were administered a single dose of Toradol and subjected to a single impact and rats that were subjected to a single impact only. In both impact groups there were transient changes in cognitive ability as measured by the Morris Water Maze.

Comparison of ACL Strain in the MCL-Deficient and MCL-Reconstructed Knee During Simulated Landing in a Cadaveric Model.

BACKGROUND: Noncontact anterior cruciate ligament (ACL) injury after valgus landing has been reported and studied biomechanically. However, the role of the medial collateral ligament (MCL) in dissipating these forces has not been fully elucidated. Purpose/Hypothesis: The purpose of this study was to investigate the role that the MCL plays in ACL strain during simulated landing. The hypothesis was that ACL strain would increase significantly in MCL-incompetent knees compared with the native knee and that reconstructing the MCL would return the values to those of the intact knee. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen human cadaveric knees were used in this study. A materials testing machine applied a force of 2× body weight over 60 milliseconds to simulate landing after a jump. The knees were tested in 12 loading conditions, consisting of full extension or 15° of flexion combined with 7° of valgus or neutral alignment while the tibia was in external rotation, neutral rotation, or internal rotation. This test procedure was repeated on each specimen with the MCL transected and reconstructed. The superficial and deep MCL was transected along with the posterior oblique ligament, which was thought to simulate a worst case scenario. The MCL was reconstructed by use of semitendinosus and gracilis tendon grafts. RESULTS: During internal rotation at 0° of flexion and 0° of valgus, both the intact ( P = .005) and the reconstructed ( P = .004) MCL states placed significantly lower strain on the ACL than did the transected MCL. The reconstructed MCL state at 0° of flexion and 7° of valgus ( P = .049) along with 15° of flexion and 0° of valgus ( P = .020) also placed significantly lower strain on the ACL than did the transected MCL. For external rotation testing at 0° of flexion and 7° of valgus, the reconstructed MCL state placed significantly lower strain on the ACL than did the transected MCL ( P = .039). Finally, during neutral rotation, the ACL strain at 0° of valgus and 0° of flexion, and at 7° of valgus and 0° of flexion was significantly lower for the MCL-intact groups ( P < .028) and MCL-reconstructed groups ( P < .016) than the MCL-transected groups. CONCLUSION: The current findings demonstrate that during valgus landing, a knee with an incompetent MCL puts the ACL under increased strain. These values are highest in full extension with the tibia in internal and neutral rotation. This increased strain can be reduced to baseline levels with reconstruction. CLINICAL RELEVANCE: A knee with an incompetent MCL puts the ACL under increased strain. Once the MCL has healed in an elongated manner, MCL reconstruction should be considered.

Biomechanical properties of tenotomy versus biceps knot in a cadaver model.

BACKGROUND: Biceps tenotomy and biceps tenodesis are the primary methods of treating biceps pathology. This study describes a new technique of tenotomy with the goal of autotenodesis to give the biceps a higher load to failure and decreased chance of a Popeye deformity. PURPOSE: The purpose of this study was to evaluate the strength of the "biceps knot", which is an outlet tenodesis of the biceps tendon and compare the biomechanical properties of this technique to tenotomy. METHODS: Ten matched cadaver shoulder pairs were used. In the tenotomy group, an arthroscopic tenotomy was performed at the labral biceps junction using a narrow angled biter. For the biceps knot group, a self-retrieving suture passing device was used to pass a suture as far lateral as possible. The suture was passed from just distal to the biceps insertion on the superior labrum and tied with a standard non-sliding arthroscopic knot. The humerus and biceps tendon were rigidly fixed to a materials testing machine and cyclically loaded at 10-20 N for 100 cycles at 1 Hz. After cyclic testing, a 2 N preload was placed on the tendon and the tendon was pulled in line with the bicipital groove until failure. RESULTS: The peak load to failure for the biceps knot was 58.9 N (SEM 8.2 N) and 37.3 N (SEM 4.6 N) for the tenotomy group (p = 0.046). The average stiffness for the biceps knot group was 4.2 N/mm (SEM 0.4 N/mm) and 3.2 N/mm (SEM 0.2 N/mm) for the tenotomy group (p = 0.031). CONCLUSION: Performing the biceps knot is a quick, easy and cost effective alternative to the current tenodesis options available.

A Biomechanical Comparison of Isometric and Anatomic Medial Patellofemoral Ligament Reconstruction.

The purpose of this study was to compare two different methods of medial patellar femoral ligament (MPFL) reconstructions: isometric and anatomic. These were then compared with the native MPFL. Fourteen fresh frozen cadaveric knees were carefully dissected to expose the MPFL. The patella was laterally translated 10 mm using an Instron and values were recorded for the intact ligament and the reconstructions. Neither the anatomic nor the isometric reconstructions completely restored the biomechanical properties of the intact MPFL. There were fewer differences between the isometric reconstruction and the intact specimens. The higher forces and stiffer constructs that occurred with the anatomic reconstruction may suggest that this reconstruction technique could overconstrain the patellofemoral joint.

Temperature Change When Drilling Near the Distal Femoral Physis in a Skeletally Immature Ovine Model.

BACKGROUND: The possibility of physeal injury during anterior cruciate ligament reconstruction in the pediatric population is a concern. The purpose of this study was to determine whether drilling at or near the physis could cause a temperature increase that could trigger chondrolysis. METHODS: Skeletally immature cadaveric lamb distal femurs were used for this study and randomly placed in 1 of 6 groups (n=10 in each group). We examined the 8 and 10 mm Flipcutter at a distance of 0.5 mm from the physis and an 8 and 10 mm acorn-tipped reamer at a distance of 0.5 and 3.0 mm from the physis. During drilling, temperature change at the distal femoral physis was continuously measured until the temperature decreased to the original value. RESULTS: An interreamer comparison yielded a significant difference when drilling 0.5 mm from the physis (P=0.001). Pair-wise Mann-Whitney post hoc tests were performed to further evaluate the differences among the groups. The 8 mm FlipCutter had a significantly higher maximum temperature (39.8±1.4°C) compared with the 10 mm FlipCutter (38.0±0.6°C, P=0.001), 8 mm acorn-tipped reamer (38.1±0.9°C, P=0.007), and 10 mm acorn-tipped reamer (37.5±0.3°C, P<0.001). CONCLUSIONS: The risk of thermal-induced injury to the physis is low with an all epiphyseal drilling technique, when a traditional acorn-tipped reamer over a guidepin is utilized, even if the drilling occurs very close to the physis. In addition, the risk of drilling with a FlipCutter is low, but may be greater than a traditional reamer. CLINICAL RELEVANCE: Thermal-induced necrosis is a realistic concern, due to the characteristics of the distal femoral physis, and the propensity for this physis to respond poorly to injury. Our study supports that drilling near the physis can be done safely, although smaller reamers and nontraditional designs may generate higher heat. LEVEL OF EVIDENCE: Level I-basic science.

Load to Failure and Stiffness: Anchor Placement and Suture Pattern Effects on Load to Failure in Rotator Cuff Repairs.

BACKGROUND: Rotator cuff tendinopathy is a frequent cause of shoulder pain that can lead to decreased strength and range of motion. Failures after using the single-row technique of rotator cuff repair have led to the development of the double-row technique, which is said to allow for more anatomical restoration of the footprint. PURPOSE: To compare 5 different types of suture patterns while maintaining equality in number of anchors. The hypothesis was that the Mason-Allen-crossed cruciform transosseous-equivalent technique is superior to other suture configurations while maintaining equality in suture limbs and anchors. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 25 fresh-frozen cadaveric shoulders were randomized into 5 suture configuration groups: single-row repair with simple stitch technique; single-row repair with modified Mason-Allen technique; double-row Mason-Allen technique; double-row cross-bridge technique; and double-row suture bridge technique. Load and displacement were recorded at 100 Hz until failure. Stiffness and bone mineral density were also measured. RESULTS: There was no significant difference in peak load at failure, stiffness, maximum displacement at failure, or mean bone mineral density among the 5 suture configuration groups (P < .05). CONCLUSION: According to study results, when choosing a repair technique, other factors such as number of sutures in the repair should be considered to judge the strength of the repair. CLINICAL RELEVANCE: Previous in vitro studies have shown the double-row rotator cuff repair to be superior to the single-row repair; however, clinical research does not necessarily support this. This study found no difference when comparing 5 different repair methods, supporting research that suggests the number of sutures and not the pattern can affect biomechanical properties.

The effect of continuous interscalene brachial plexus block with 0.125% bupivacaine vs 0.2% ropivacaine on pain relief, diaphragmatic motility, and ventilatory function.

STUDY OBJECTIVE: Outpatient continuous interscalene brachial plexus blocks containing bupivacaine or ropivacaine are commonly used to control pain after shoulder surgery. Interscalene blocks cause hemidiaphragmatic paresis. Because ropivacaine preferentially blocks sensory fibers, it may cause less blockade of the phrenic nerve. The purpose of this study was to evaluate the effects of 2 common continuous interscalene brachial plexus infusions: 0.125% bupivacaine vs 0.2% ropivacaine. The study hypothesis is that respiratory function will be less attenuated using ropivacaine than bupivacaine without affecting pain relief. DESIGN: Study design was a prospective randomized double-blind study, registered (NCT 02059070), with institutional review board approval and written informed consent. SETTING: The setting was the preoperative and postoperative area in an orthopedic teaching hospital. PATIENTS: Outpatients scheduled for shoulder arthroscopic surgery were included. INTERVENTIONS: All patients underwent baseline measurements and interscalene catheter placement, then randomized to receive pumps containing either 0.2% ropivacaine or 0.125% bupivacaine. MEASUREMENTS: Study measurements included preoperative and postoperative bedside spirometry and ultrasonographic evaluations of diaphragmatic excursion, postoperative pain scores, and postdischarge oral opioid (oxycodone) consumption. MAIN RESULTS: There were no statistically significant differences between bupivacaine vs ropivacaine in outcomes of forced expiratory volume at 1 second change (-22% ± 18.3% vs -29% ± 14.9%), diaphragmatic excursion (-81.4% ± 37.95% vs -75.5% ± 35.1%), VAS pain scores at rest (4.9 ± 2.9 vs 3.5 ± 2.8), or oral opioid consumption (33.7 ± 24.3 mg vs 35.1 ± 33.9 mg). CONCLUSIONS: There was no difference in respiratory dysfunction or opioid requirements between interscalene continuous peripheral nerve blocks with 0.125% bupivacaine or 0.2% ropivacaine. Further study is required to identify anesthetic infusates that will control pain while decreasing the attenuation of pulmonary function.

Soccer-Related Injuries in Children and Adults Aged 5 to 49 Years in US Emergency Departments From 2000 to 2012.

BACKGROUND: An increase in soccer-related injuries occurred in the United States between 2000 and 2012; however, most studies of soccer-related injuries have only examined the pediatric population and not adults. HYPOTHESIS: The number of soccer injuries is increasing in both the pediatric and adult populations. There are differences in injury types and counts when comparing male and female players within various age groups. STUDY DESIGN: Descriptive epidemiology study. LEVEL OF EVIDENCE: Level 4. METHODS: This retrospective analysis surveyed the US Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS) database from 2000 to 2012 for soccer-related injuries in children and adults aged 5 to 49 years. RESULTS: From 2000 to 2012, there were an estimated 2,472,066 soccer-related injuries among 5- to 49-year-olds; 629,994 (25.5%) in adults (aged 20-49 years). The overall estimated pediatric injury count increased significantly over the time period (R (2) = 0.764, P < 0.001). In the 20- to 49-year age range, there was also a significant increase in the estimated number of injuries over the 13-year period, from 41,292 injuries in 2000 to 55,743 in 2012 (R (2) = 0.719, P < 0.001). The estimated injury counts for male players were significantly higher than female players in any given year for all age groups (P < 0.001). Girls aged 5 to 19 years were more likely to have lower extremity injuries than boys (odds ratio [OR], 1.256; 95% CI, 1.214-1.299; P < 0.001). The most common injuries reported were strain/sprains (33.3%), fractures (23.7%), and contusions and abrasions (17.4%) within the 5- to 49-year age category. In both sexes, strains and sprains were significantly lower among 5- to 19-year-olds in comparison with 20- to 49-year-olds (OR, 0.740; 95% CI, 0.714-0.766; P < 0.001). CONCLUSION: There are age- and sex-related differences in estimated injury count, body part injured, type of injury, and hospital admissions for soccer. Also, estimated injury count increased over the 2000 to 2012 time period. CLINICAL RELEVANCE: This study demonstrates that there are differences between pediatric and adult injuries, based on sex, body part, type of injury, and hospital admissions.

Biomechanical properties of labral repair: simple versus vertical suture pattern.

The goal of this study was to evaluate contact area and surface pressure as a result of different suture patterns in the treatment of anterior shoulder instability caused by a Bankart lesion. Loads were applied through the humeral head to the glenoid surface in the intact shoulder and after simple suture labral repair (n=10) and vertical mattress labral repair (n=9). Peak contact pressure, mean contact pressure, and contact area were recorded for 0°, 45°, and 90° shoulder abduction, and then the repair was loaded to failure. A significant increase (P<.05) in mean contact pressure and peak contact pressure occurred in both repair groups at 90° abduction. No difference was seen between the 2 repair groups. Total contact area significantly decreased after both repairs at 90° abduction at 220 N force (P<.05). No significant difference occurred in load to failure between the groups. Joint loading properties can be affected by alterations in contact pressure within the glenohumeral joint. In the current study, the authors found no significant difference in contact pressure between the 2 repair groups. However, they found a significant increase in mean contact pressure and peak pressure between the intact specimen and the 2 repair groups. Both simple repair and vertical mattress repair provided similar load to failure for labral repair. Current techniques used to perform Bankart repair may need to be altered to provide the stability of current techniques with more normal glenohumeral joint contact pressure.