Cyclic loading induces anabolic gene expression in ACLs in a load-dependent and sex-specific manner.

Anterior cruciate ligament (ACL) injuries are historically thought to be a result of a single acute overload or traumatic event. However, recent studies suggest that ACL failure may be a consequence of fatigue damage. Additionally, the remodeling response of ACLs to fatigue loading is unknown. Therefore, the objective of this study was to investigate the remodeling response of ACLs to cyclic loading. Furthermore, given that women have an increased rate of ACL rupture, we investigated whether this remodeling response is sex specific. ACLs were harvested from male and female New Zealand white rabbits and cyclically loaded in a tensile bioreactor mimicking the full range of physiological loading (2, 4, and 8 MPa). Expression of markers for anabolic and catabolic tissue remodeling, as well as inflammatory cytokines, was quantified using quantitative reverse transcription polymerase chain reaction. We found that the expression of markers for tissue remodeling of the ACL is dependent on the magnitude of loading and is sex specific. Male ACLs activated an anabolic response to cyclic loading at 4 MPa but turned off remodeling at 8 MPa. These data support the hypothesis that noncontact ACL injury may be a consequence of failed tissue remodeling and inadequate repair of microtrauma resulting from elevated loading. Compared to males, female ACLs failed to increase anabolic gene expression with loading and exhibited higher expression of catabolic genes at all loading levels, which may explain the increased rate of ACL tears in women. Together, these data provide insight into load-induced ACL remodeling and potential causes of tissue rupture.

Controlled Degradation of Polycaprolactone Polymers through Ultrasound Stimulation.

This study describes the development of an ultrasound-responsive polymer system that provides on-demand degradation when exposed to high-intensity focused ultrasound (HIFU). Diels-Alder cycloadducts were used to crosslink polycaprolactone (PCL) polymers and underwent a retro Diels-Alder reaction when stimulated with HIFU. Two Diels-Alder polymer compositions were explored to evaluate the link between reverse reaction energy barriers and polymer degradation rates. PCL crosslinked with isosorbide was also used as a non-Diels-Alder-based control polymer. An increase of HIFU exposure time and amplitude correlated with an increase of PCL degradation for Diels-Alder-based polymers. Ultrasound imaging during HIFU allowed for real-time visualization of the on-demand degradation through cavitation-based mechanisms. The temperature surrounding the sample was monitored with a thermocouple during HIFU stimulation; a minimal increase in temperature was observed. PCL polymers were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), optical profilometry, and mechanical testing. PCL degradation byproducts were identified by mass spectrometry, and their cytocompatibility was evaluated in vitro. Overall, this study demonstrated that HIFU is an effective image-guided, external stimulus to control the degradation of Diels-Alder-based PCL polymers on-demand.

Quadriceps Dysfunction Following Joint Preservation Surgery: A Review of the Pathophysiologic Basis and Mitigation Strategies.

PURPOSE OF REVIEW: To characterize quadriceps muscle dysfunction associated with knee joint preservation surgery, with a focus on its pathophysiology and promising approaches to mitigate its impact on clinical outcomes. RECENT FINDINGS: Quadriceps dysfunction (QD) associated with knee joint preservation surgery results from a complex interplay of signaling, related to changes within the joint and from those involving the overlying muscular envelope. Despite intensive rehabilitation regimens, QD may persist for many months postoperatively and negatively impact clinical outcomes associated with various surgical procedures. These facts underscore the need for continued investigation into the potential detrimental effects of regional anesthetic and intraoperative tourniquet use on postoperative quadriceps function, with an outward focus on innovation within the field of postoperative rehabilitation. Neuromuscular stimulation, nutritional supplementation, cryotherapy, blood flow restriction (BFR), and open-chain exercises are all potential additions to postoperative regimens. There is compelling literature to suggest that these modalities are efficacious and may diminish the magnitude and duration of postoperative QD. A clear understanding of QD, with respect to its pathophysiology, should guide perioperative treatment and rehabilitation strategies and influence ongoing rehabilitation-based research and innovation. Moreover, clinicians must appreciate the magnitude of QD's effect on diminished clinical outcomes, risk for re-injury and patients' ability (or inability) to return to pre-injury level of activity following knee joint preservation procedures.

Guidelines for Proper Reporting of Clinical Significance, Including Minimal Clinically Important Difference, Patient Acceptable Symptomatic State, Substantial Clinical Benefit, and Maximal Outcome Improvement.

Patient-reported outcome measures (PROM) need to be responsive, reliable, and validated for the specific condition or treatment. PROMs also need to exhibit a dose-dependent response across a diverse patient population, unlimited by floor and ceiling effects. Statistically significant differences between compared groups might not always represent clinically important differences. Measures of clinical significance reflect a spectrum of patient satisfaction after an intervention. A noticeable difference to the patient is assessed with minimal clinically important difference (MCID), patient satisfaction by patient acceptable symptomatic state (PASS), and a "considerable" improvement by substantial clinical benefit (SCB). Clinical relevance measured by these clinically significant outcomes (CSO) are limited by ceiling effects. Maximal outcome improvement (MOI) might more accurately account for patients with higher baseline or preoperative PROMs, thereby limiting ceiling effects. The acts of measuring (and reporting) patient-centered endpoints may actually be of greater importance than collecting objective clinician-measured data. As the old surgeon's aphorism goes, "nothing ruins good results like good follow-up."

Risk Factors For Prolonged Opioid Use After Spine Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: Our purpose was to evaluate factors associated with increased risk of prolonged post-operative opioid pain medication usage following spine surgery, as well as identify the risk of various post-operative complications that may be associated with pre-operative opioid usage. METHODS: The MarketScan commercial claims and encounters database includes approximately 39 million patients per year. Patients undergoing cervical and lumbar spine surgery between the years 2005-2014 were identified using CPT codes. Pre-operative comorbidities including DSM-V mental health disorders, chronic pain, chronic regional pain syndrome (CRPS), obesity, tobacco use, medications, and diabetes were queried and documented. Patients who utilized opioids from 1-3 months prior to surgery were identified. This timeframe was chosen to exclude patients who had been prescribed pre- and post-operative narcotic medications up to 1 month prior to surgery. We utilized odds ratios (OR), 95% Confidence Intervals (CI), and regression analysis to determine factors that are associated with prolonged post-operative opioid use at 3 time intervals. RESULTS: 553,509 patients who underwent spine surgery during the 10-year period were identified. 34.9% of patients utilized opioids 1-3 months pre-operatively. 25% patients were still utilizing opioids at 6 weeks, 17.3% at 3 months, 12.7% at 6 months, and 9.0% at 1 year after surgery. Pre-operative opioid exposure was associated with increased likelihood of post-operative use at 6-12 weeks (OR 5.45, 95% CI 5.37-5.53), 3-6 months (OR 6.48, 95% CI 6.37-6.59), 6-12 months (OR 6.97, 95% CI 6.84-7.11), and >12 months (OR 7.12, 95% CI 6.96-7.29). Mental health diagnosis, tobacco usage, diagnosis of chronic pain or CRPS, and non-narcotic neuromodulatory medications yielded increased likelihood of prolonged post-op opioid usage. CONCLUSIONS: Pre-operative narcotic use and several patient comorbidities diagnoses are associated with prolonged post-operative opioid usage following spine surgery. Chronic opioid use, diagnosis of chronic pain, or use of non-narcotic neuromodulatory medications have the highest risk of prolonged post-operative opioid consumption. Patients using opiates pre-operatively did have an increased 30 and 90-day readmission risk, in addition to a number of serious post-operative complications. This data provides spine surgeons a number of variables to consider when determining post-operative analgesia strategies, and provides health systems, providers, and payers with information on complications associated with pre-operative opioid utilization.

The effect of cigarette smoke versus vaporized nicotine on healing of a rat femur.

INTRODUCTION: Little data exists regarding the effects of vaporized nicotine on healing. Our goal was to compare vaporized nicotine, combusted nicotine and control with respect to bone healing in a rat femur fracture model. MATERIALS AND METHODS: Forty-five male Sprague Dawley rats were divided into three equal cohorts. Rats were exposed to two cigarettes daily, an equivalent dose of vaporized nicotine, or control, six days a week. Exposures occurred for 4 weeks prior to iatrogenic femur fracture and intramedullary repair. Four additional weeks of exposure occurred prior to sacrifice. Radiographic, biomechanical and histologic analysis was conducted. RESULTS: No significant difference between the three groups was identified for total mineralized bone volume (p = 0.14), total volume of mature bone (p = 0.12) or immature bone (p = 0.15). Importantly, less total mineralized bone volume and immature bone volume was seen in the vaporized nicotine group compared to combusted tobacco, but results were not significant. Biomechanical testing revealed no significant difference in group torsional stiffness (p = 0.92) or maximum torque (p = 0.31) between the three groups. On histologic analysis, chi-square testing showed no significant difference in any category. CONCLUSIONS: This exploratory study compared combusted nicotine, vaporized nicotine and a control on rat femur fractures. While no statistically significant differences were identified, there were trends showing less total mineralized bone volume and immature bone volume in the vaporized nicotine group compared to the other groups. Additional study is warranted based on our findings.

Ultrasound-Responsive Hydrogels for On-Demand Protein Release.

The development of tunable, ultrasound-responsive hydrogels that can deliver protein payload on-demand when exposed to focused ultrasound is described in this study. Reversible Diels-Alder linkers, which undergo a retro reaction when stimulated with ultrasound, were used to cross-link chitosan hydrogels with entrapped FITC-BSA as a model protein therapeutic payload. Two Diels-Alder linkage compositions with large differences in the reverse reaction energy barriers were compared to explore the influence of linker composition on ultrasound response. Selected physicochemical properties of the hydrogel construct, its basic degradation kinetics, and its cytocompatibility were measured with respect to Diels-Alder linkage composition. Focused ultrasound initiated the retro Diels-Alder reaction, controlling the release of the entrapped payload while also allowing for real-time visualization of the ongoing process. Additionally, increasing the focused ultrasound amplitude and time correlated with an increased rate of protein release, indicating stimuli responsive control.

Editorial Commentary: Clinical Improvements of Superior Capsular Reconstruction Are Not Due to Maintained Dynamic Acromiohumeral Distance.

Biomechanical data often help inform clinical decision-making in orthopaedic surgery. However, there are times when the biomechanical data and clinical data do not align. This is seen in cases of statistical but clinically irrelevant differences. This is also seen at times in cases of demonstrated clinical improvements with a poorly understood mechanism. Superior capsular reconstruction has gained significant traction since the original description in 2012. It has taken a central role in the armamentarium of treatment options of irreparable rotator cuff tears. There is robust published literature on the time zero biomechanics of superior capsular reconstruction and its stabilizing effects on the glenohumeral joint, especially with regards to superior migration of the humeral head. There also is demonstrated good early patient-reported outcomes with superior capsular reconstruction. However, the cause and effect may not be as simple as the biomechanical studies may suggest, and the underlying mechanism of why the superior capsular reconstruction appears to improve early outcomes remains poorly understood. These mechanisms are important to understand in order to inform technique changes and improvements and help us optimize treatment of the patient with an irreparable rotator cuff tear.

Opioid Use, Perioperative Risks, and Associated Postoperative Complications in Foot and Ankle Surgery.

INTRODUCTION: Opioid abuse has become a national crisis. Published data demonstrate that patients undergoing foot and ankle surgery are left with excess narcotic medications postoperatively. The purpose of our study was to evaluate factors associated with prolonged postoperative opioid use following foot and ankle surgery and identify associations between preoperative opioid use and postoperative complications. METHODS: MarketScan commercial claims and encounters database was searched to identify foot and ankle patients. Preoperative comorbidities were queried and documented. Patients utilizing opioids 1 to 3 months prior to surgery were identified. Adjusted odds ratios and 95% CIs were calculated using multivariable logistic regression to determine associations between opioid use (preoperatively and postoperatively), readmission, and complications. RESULTS: A total of 112 893 patients were included in the study. Preoperative use had a statistically significant association with postoperative use out to 1 year. Tobacco use, chronic pain, mental health diagnosis, and nonopioid medications had a statistically significant association with postoperative use. Preoperative opioid use had a statistically significant association with readmission and postoperative complications. CONCLUSION: Our study found a number of factors associated with prolonged postoperative opioid use (preoperative use, tobacco use, chronic pain, mental health disorders, and certain nonopioid medications). We identified an association between preoperative opioid use and postoperative complications and readmission. LEVELS OF EVIDENCE: Prognostic Level IV Evidence.

Editorial Commentary: Early Detection and Treatment Improves Short-Term Outcomes After Shoulder Anchor Arthropathy, but an Ounce of Prevention Is Worth a Pound of Cure.

Anchor arthropathy is a rare, but devastating, complication after arthroscopic labral repair and shoulder stabilization. Early recognition and treatment in the form of removal of anchor and suture material, loose bodies, and potential revision stabilization significantly improve short-term outcomes. The entity of anchor arthropathy may be difficult to diagnose, and a high index of suspicion is needed when a patient presents postoperatively with pain and stiffness beyond atypical for their time in rehab. In the end, while early treatment can be favorable, prevention with meticulous attention to detail on anchor placement, position, and potential use of knotless anchors is strongly recommended.

Biomechanical Effects of Δ9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), the Major Constituents of Cannabis, in a Sprague Dawley Rat Achilles Tendon Surgical Repair Model: A Pilot Study.

BACKGROUND: The use of cannabis is common among athletes and the US population at large. Cannabinoids are currently being evaluated as alternatives to opioid medications for chronic pain management. However, the effects of recreational and/or medical use of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on musculoskeletal injury and healing remain largely unknown. HYPOTHESIS/PURPOSE: The purpose of this study was to evaluate the biomechanical effects of CBD and THC on tendon-to-tendon healing in a rat Achilles tendon repair model. The hypothesis was that rats administered CBD would demonstrate decreased tensile load to failure of surgically repaired Achilles tendons compared with the THC and control groups. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 33 Sprague Dawley rats underwent Achilles tendon surgical transection and repair and were randomized to receive subcutaneous injection of THC, CBD, or vehicle once daily starting on the day of surgery and for 5 total days. After sacrifice, biomechanical tensile load-displacement testing was performed to determine Achilles tendon load to failure and stiffness. Data were analyzed by 1-way analysis of variance. RESULTS: The THC group demonstrated the highest median load to failure, 18.7 N (95% CI, 15.3-19.2 N); the CBD group had the second highest at 16.9 N (95% CI, 15.1-19.8 N), and the control group had the lowest at 14.4 N (95% CI, 12.1-18.3 N). Stiffness was highest in the THC group at 4.1 N/mm (95% CI, 2.7-5.1 N/mm) compared with 3.6 N/mm (95% CI, 2.9-4.1 N/mm) for the CBD group and 3.6 N/mm (95% CI, 2.8-4.3 N/mm) for the control group. No statistically significant differences for strength and stiffness were observed between the groups. CONCLUSION: In this pilot study using an animal tendon-to-tendon repair model, neither THC nor CBD resulted in altered biomechanical characteristics compared to control. CLINICAL RELEVANCE: Cannabinoids do not appear to adversely affect Achilles tendon healing.

Nicotine Exposure Via Electronic Cigarettes Significantly Impedes Biomechanical Healing Properties of Tendon Healing in a Rat Model.

PURPOSE: To evaluate the biomechanical and histologic effects on Achilles tendon repair of inhaled combusted tobacco versus nicotine exposure via electronic cigarette versus a control group in a small-animal model (Sprague-Dawley rat). METHODS: Fifty-four Sprague-Dawley rats were randomized into 3 groups: combusted tobacco, e-cigarettes, or control. Experimental rats were exposed to research cigarettes or e-cigarette vapor in a smoking chamber for 4 weeks. Surgical transection and repair of the Achilles tendon were then completed, followed by 2 additional weeks of exposure. Achilles tendons were harvested, and biomechanical tensile testing was performed. Histologic evaluation was completed, including hematoxylin-eosin staining, trichrome staining, and immunohistochemistry analysis for type I and type III collagen. RESULTS: The control group showed the highest mean tensile load to failure, at 41.0 ± 10.4 N (range, 18.3-55.1 N); the cigarette cohort had the second highest mean, at 37.3 ± 11.1 N (range, 14.0-54.7 N); and finally, the vaping group had the lowest mean, at 32.3 ± 8.4 N (range, 17.8-45.1 N). One-way analysis of variance showed a significant difference in load to failure when comparing the control group with the e-cigarette group (P = .026). No statistical difference was detected between the control group and cigarette group (P = .35) or between the e-cigarette group and cigarette group (P = .23). Stiffness and qualitative histologic analysis showed no difference among groups. CONCLUSIONS: This investigation shows that in a rat model, nicotine exposure via e-cigarette significantly impedes the biomechanical healing properties of Achilles tendon surgical repair. CLINICAL RELEVANCE: The results indicate that although e-cigarettes are often used as a perceived "safer" alternative to smoking, their use may have a detrimental effect on tendon load to failure.

Nearly One-Third of Published Systematic Reviews and Meta-analyses Yield Inconclusive Conclusions: A Systematic Review.

PURPOSE: To perform a systematic review that determines the percentage of published orthopedic surgery and sports medicine systematic reviews and meta-analyses that have a conclusive conclusion. METHODS: A systematic review was performed using PRISMA guidelines. Six high-quality orthopedics journals were chosen for analysis over a 10-year eligibility period. Systematic reviews and meta-analyses published in these journals were included in the investigation. Narrative, scoping, and umbrella reviews were excluded. A systematic review or meta-analysis was defined as having an inconclusive conclusion if the conclusion in the manuscript body or abstract was stated directly as inconclusive, indeterminate, unknown, or having a lack of evidence (or no evidence). A conclusive conclusion stated a direct answer to the study's primary and/or accessory outcomes. Due to the categorical nature of the data, comparisons were made using χ2 test and logistic regression. RESULTS: There were 1,108 systematic reviews/meta-analyses analyzed (30.9 ± 70.3 studies analyzed per review). More reviews (69.9%) were published with conclusive conclusions rather than without (30.1%). More reviews were surgical (73%) rather than nonsurgical. The United States and North America published the most reviews by country and continent, respectively. There were statistically significant differences between countries (highest proportion with China) and continents (highest proportion with Asia) based on the number of conclusive conclusions in published reviews, respectively. There were no significant differences in the proportion of conclusive conclusion reviews between the 6 analyzed journals. Australia published the largest proportion on nonsurgical reviews. The British Journal of Sports Medicine published a significantly higher proportion of nonsurgical reviews than the other 5 journals. There was no temporal relationship with the proportion of conclusive conclusion reviews. CONCLUSIONS: This systematic review observed that only 70% of orthopedic systematic reviews and meta-analyses published in 6 high-quality orthopedic journals over a 10-year eligibility period had conclusive conclusions. LEVEL OF EVIDENCE: Level IV, systematic review and/or meta-analysis of studies with Levels I to IV.

Increased Load to Failure in Biceps Tenodesis With All-Suture Suture Anchor Compared With Interference Screw: A Cadaveric Biomechanical Study.

PURPOSE: To compare the biomechanical characteristics of a single radially expanding all-suture anchor with an interference screw for open subpectoral long head of biceps tendon (LHBT) tenodesis. METHODS: Eighteen fresh-frozen matched-pair human cadaveric humeri were used for this biomechanical study. The matched pair humeri were randomly assigned into 2 experimental biceps tenodesis groups: conventional interference screw (CIS) or all-suture suture anchor (ASSA). Open subpectoral LHBT tenodesis was then performed and biomechanical testing was performed using a servohydraulic test frame. A preload of 5 N was applied for 2 minutes before cyclic loading. Displacement was recorded at cycle 300 (D300) and cycle 500 (D500) and at ultimate failure. Data recorded included displacement, load to failure, displacement at failure. Paired t test was used for analysis. RESULTS: Decreased displacement was observed for the CIS group at D300 (1.67 ± 0.57 mm vs 3.35 ± 2.24 mm; P = .04), D500 (2.00 ± 0.76 mm vs 3.87 ± 2.20 mm; P = .04), and at failure (5.17 ± 3.05 mm vs 10.76 ± 2.66 mm; P < .001). Load to failure was lower in CIS specimens (170 ± 24.5 N vs 217.8 ± 51.54 N; P = .02). Failure in each case was tendon pullout for all CIS specimens; in ASSA 6 specimens failed as the suture pulled through the tendon, 2 specimens failed by suture breakage. No difference in stiffness was observed between the 2 groups (CIS = 98.33 ± 22.98 N/m vs ASSA = 75.94 ± 44.83 N/m; P = .20). CONCLUSIONS: Our study found that open subpectoral biceps tenodesis performed with an ASSA construct results in increased load to failure as compared with CIS. However, the CIS did demonstrate decreased displacement as compared to ASSA in this cadaveric biomechanical study. CLINICAL RELEVANCE: ASSA and CIS at time zero provide fixation as indicated by the provider intraoperatively for LHBT tenodesis. ASSA, however, does remove less cortical bone than does CIS and therefore produces a smaller stress riser in the proximal humerus. Further testing as to the integrity of ASSA is warranted to determine the integrity of the tenodesis with cyclical loading.

Three-Dimensional Bioprinting of Articular Cartilage: A Systematic Review.

OBJECTIVE: Treatment of chondral injury is clinically challenging. Available chondral repair/regeneration techniques have significant shortcomings. A viable and durable tissue engineering strategy for articular cartilage repair remains an unmet need. Our objective was to systematically evaluate the published data on bioprinted articular cartilage with regards to scaffold-based, scaffold-free and in situ cartilage bioprinting. DESIGN: We performed a systematic review of studies using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed and ScienceDirect databases were searched and all articles evaluating the use of 3-dimensional (3D) bioprinting in articular cartilage were included. Inclusion criteria included studies written in or translated to English, published in a peer-reviewed journal, and specifically discussing bioinks and/or bioprinting of living cells related to articular cartilage applications. Review papers, articles in a foreign language, and studies not involving bioprinting of living cells related to articular cartilage applications were excluded. RESULTS: Twenty-seven studies for articular cartilage bioprinting were identified that met inclusion and exclusion criteria. The technologies, materials, cell types used in these studies, and the biological and physical properties of the created constructs have been demonstrated. CONCLUSION: These 27 studies have demonstrated 3D bioprinting of articular cartilage to be a tissue engineering strategy that has tremendous potential translational value. The unique abilities of the varied techniques allow replication of mechanical properties and advances toward zonal differentiation. This review demonstrates that bioprinting has great capacity for clinical cartilage reconstruction and future in vivo implantation.

Prevalence of shoulder labral abnormalities on MRI in a non-athletic asymptomatic young adult population.

OBJECTIVE: To determine the prevalence of shoulder (specifically labral) abnormalities on MRI in a young non-athletic asymptomatic cohort. We hypothesize that this population will have fewer labral abnormalities than an athletic population. MATERIALS AND METHODS: In this cross-sectional study, non-athletic young adults age 18-29 with no history of shoulder pain received bilateral shoulder MRIs. A total of 58 total shoulder MRIs were completed on a 3-T MRI scanner (PRISMA-Fit Siemens Medical). MRIs were read by two board-certified fellowship-trained musculoskeletal radiologists at two time points 3 months apart to determine prevalence of labral and other shoulder anatomy abnormalities. Kappa statistics and the associated 95% confidence intervals were computed for inter/intra-reader reliability. Fisher's exact test was used to compare rates of abnormalities in our study with a similarly designed study involving ice hockey athletes. RESULTS: Prevalence of labral abnormalities was 9% (5/58). Kappa coefficient was 1.0 for both readers for intra-reader reliability and 0.57 for inter-reader reliability of labral abnormalities. We further compared our results in asymptomatic athletes with previously published work using the same protocol at our institution. The prevalence of labral abnormalities on MRI in asymptomatic professional and collegiate ice hockey players (49 imaged shoulders) was 24%, which demonstrated a statistically significant (p value < 0.05) difference compared with our data with a p value of 0.03. CONCLUSIONS: Non-athletic young adults with no history of shoulder pain/injury had an overall prevalence of shoulder MRI abnormalities less than asymptomatic professional and collegiate ice hockey players in a similarly designed study.

Preoperative Opioid Use Is Associated With Persistent Use, Readmission and Postoperative Complications After Arthroscopic Knee Surgery.

PURPOSE: To evaluate factors associated with prolonged opioid use after arthroscopic knee surgery and to identify associations between preoperative usage and postoperative complications. METHODS: The MarketScan commercial database was searched to identify patients who underwent arthroscopic knee surgery from 2005 to 2014 (based on Current Procedure Terminology code). Preoperative comorbidities including Diagnostic and Statistical Manual of Mental Disorders mental health disorders, chronic pain, chronic regional pain syndrome, obesity, tobacco use, non-narcotic medications and diabetes were queried and documented. Patients who filled opioid prescriptions 1 to 3 months before surgery were identified. Patients who filled opioid prescriptions after surgery were identified. Adjusted odds ratios and 95% confidence intervals were calculated using multivariable logistic regression analysis to determine factors associated with prolonged postoperative opioid use. RESULTS: In total, 1,012,486 patients who underwent arthroscopic knee surgery were identified, and we determined which of these patients were on preoperative opioids. Preoperative opioid usage was associated with a statistically significant increased risk of usage out to 1 year. There was a statistically significant association between postoperative usage and preoperative variables (mental health diagnosis, smokers, chronic pain, chronic regional pain syndrome, and use of non-narcotic medications). There was a statistically significant association between preoperative opioid use and 90-day readmission and postoperative complications. CONCLUSION: In this study, we found that patients taking opioids 1 to 3 months before arthroscopic knee surgery have increased risk of postoperative use. Additionally, chronic opioid use, chronic pain, or use of non-narcotic medications has the highest risk of postoperative opioid use. Finally, preoperative use was associated with an increased risk of 90-day readmission. EVIDENCE: Prognostic Level IV Evidence.

Editorial Commentary: Back to the Future With the Medial Patellofemoral Complex.

The desire to better re-create the native anatomy in orthopaedic surgery-and especially knee ligament reconstruction-was an area of great debate and discussion approximately 10 years ago in anterior cruciate ligament (ACL) reconstruction. Our better and more detailed understanding of the anatomy, especially the insertional anatomy, of the ACL fueled the debate over the best surgical technique to maximize function, improve patient outcomes, and reduce long-term morbidity. While these discussions are still ongoing, detailed study of the medial patellofemoral complex (MPFC) anatomy is bringing us "back to the future" with similar discussions on how to best re-create this anatomy. Although specific techniques and surgical risks versus rewards will continue to be debated, our improved understanding of the anatomy of the MPFC, similar to our improved understanding of the ACL, ultimately will improve how MPFC reconstruction is performed and improve patient outcomes.

Hybrid Bioprinting of Zonally Stratified Human Articular Cartilage Using Scaffold-Free Tissue Strands as Building Blocks.

The heterogeneous and anisotropic articular cartilage is generally studied as a layered structure of "zones" with unique composition and architecture, which is difficult to recapitulate using current approaches. A novel hybrid bioprinting strategy is presented here to generate zonally stratified cartilage. Scaffold-free tissue strands (TSs) are made of human adipose-derived stem cells (ADSCs) or predifferentiated ADSCs. Cartilage TSs with predifferentiated ADSCs exhibit improved mechanical properties and upregulated expression of cartilage-specific markers at both transcription and protein levels as compared to TSs with ADSCs being differentiated in the form of strands and TSs of nontransfected ADSCs. Using the novel hybrid approach integrating new aspiration-assisted and extrusion-based bioprinting techniques, the bioprinting of zonally stratified cartilage with vertically aligned TSs at the bottom zone and horizontally aligned TSs at the superficial zone is demonstrated, in which collagen fibers are aligned with designated orientation in each zone imitating the anatomical regions and matrix orientation of native articular cartilage. In addition, mechanical testing study reveals a compression modulus of ≈1.1 MPa, which is similar to that of human articular cartilage. The prominent findings highlight the potential of this novel bioprinting approach for building biologically, mechanically, and histologically relevant cartilage for tissue engineering purposes.

Editorial Commentary: Sometimes You Don't Know What You've Got Until It's Gone-The Effect of Missing Data in "Big Data" Studies.

Big-data studies are powerful tools for comparative-effectiveness research, but because of the large number of included patients, they risk falsely identifying a difference when none exists because large sample sizes may result in statistically significant differences that have little clinical importance. Other limitations of big-data studies include lack of generalizability because of inclusion of only specific patient populations, lack of validated outcome measures, recording bias or clerical error, and vast troves of missing data. As such, the methods and results of big-data studies require careful scrutiny to ensure that the conclusions are correct.