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Background and Objective: Knee surgery attempts to restore the native biomechanics of the knee, improve stability, and decrease the progression of osteoarthritis (OA). However, despite improvements in surgical techniques, tissue degradation and OA are common after knee surgery, occurring in higher rates in surgical knees compared to non-surgical knees. The aim of this study is to analyze previous literature to determine which synovial fluid biomarkers contribute to knee tissue degradation and decrease patient outcomes in the post-surgical setting of the knee., Methods: A narrative review of relevant literature was performed in July 2023. Studies reporting on synovial biomarkers associated with the post-surgical knee were included., Key Content and Findings: The literature reported that proinflammatory synovial biomarkers cause cartilage degradation and turnover which eventually leads to OA. The associated biomarkers are typically present prior to physical symptoms so understanding which one's correlate to OA is important for potential therapeutic treatments in the future. Studying the preoperative, early postoperative, and late postoperative synovial biomarkers will allow physicians to develop an improved understanding of how these biomarkers progress and correlate to knee tissue degradation and OA. This understanding could lead to further developments into potential treatment options. Research into inhibiting or reversing these inflammatory biomarkers to slow the progression of knee tissue degradation has already begun and has reported some promising results but is currently limited in scope., Conclusions: Synovial fluid biomarkers in the post-surgical knee setting may contribute to decreased patient outcomes and the progression of knee tissue degradation. There is no current consensus on which of these biomarkers are the most detrimental or associated with decreased patient outcomes. With an improved understanding of the individual biomarkers, potential personalized therapeutic treatment could be used by physicians in the future to improve patient outcomes after surgery., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aoj.amegroups.com/article/view/10.21037/aoj-23-56/coif). The series “Inflammation of the Tibiofemoral Joint: Inflammatory Mediators, Treatment, and Long-Term Effects” was commissioned by the editorial office without any funding or sponsorship. N.N.D. served as the unpaid Guest Editor of the series and serves as an unpaid editorial board member of Annals of Joint from August 2022 to July 2024. J.C. is a consultant for Smith & Nephew; has received educational support from Medwest Associated; and has received research support from RTI. G.M. is a consultant for Smith & Nephew and IBSA; is on the editorial board for JBJS and Arthroscopy; and is a committee member for ISAKOS. R.F.L. is a consultant for Ossur, Smith & Nephew, and Responsive Arthroscopy; collects royalties from Ossur, Smith & Nephew, Elsevier, and Arthrex; has research grants from Ossur, Smith & Nephew, AANA, AOSSM; is on the committees for ISAKOS, AOSSM, AANA; and is on the editorial boards of AJSM, JEO, KSSTA, JKS, JISPT and OTSM. The authors have no other conflicts of interest to declare., (2024 Annals of Joint. All rights reserved.)

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to mitigate pain and inflammation associated with musculoskeletal conditions; however, there is conflicting data on the adverse effects of these drugs on tissue and bone healing. The objective of this study was to investigate the effect of NSAIDs on the healing of knee, soft tissue, and bone., Methods: A systematic literature search was conducted across PubMed/MEDLINE, Excerpta Medical Database (Embase)/Ovid, and the Cochrane Central Register of Controlled Trials databases. Clinical, animal, and in vitro studies on the effect of NSAIDs on knee healing were included. Risk of bias assessment was performed using the Cochrane bias assessment tool and Methodological Index for Non-Randomized Studies scoring system for included clinical studies, and the Systematic Review Center for Laboratory Animal Experimentation assessment tool for all included animal studies. General study population characteristics, interventions used, NSAIDs utilized, outcome measures, and study results were analyzed using descriptive statistics., Results: Fifteen articles met the inclusion criteria. Of the 15 studies, there were three clinical, ten animal, and two in vitro studies. In clinical studies, nonselective cyclooxygenase (COX) inhibitors and selective COX-2 inhibitors did not cause a significant increase in failure of anterior cruciate ligament (ACL) reconstructions or meniscal repairs with NSAID administration pre-, peri-, or post-operatively in comparison to placebo or no NSAID administration. Among animal studies assessing COX-2 inhibitor effects on soft tissue, healing was impaired (2/4), delayed but unaffected (1/4), or unaffected (1/4). In animal studies assessing COX-1 inhibitors, ligament healing was either increased (1/4), unaffected (2/4), or impaired (1/4). Meanwhile, administration of non-selective COX inhibitors in animals did not affect soft tissue (3/3) and cartilage (1/1) healing. Two in vitro studies identified a negative outcome on patellar tendon and ACL cell proliferation or viability after non-selective COX inhibition and variable results after selective COX-2 inhibition., Conclusions: Animal studies on postoperative NSAID use after knee surgery suggest that administration of selective and nonselective COX-2 inhibitors may impair healing of soft tissue, bone and tendon-to-bone; however, further clinical studies are needed to better characterize dose and duration dependent risks of NSAIDs., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aoj.amegroups.com/article/view/10.21037/aoj-23-58/coif). The series “Inflammation of the Tibiofemoral Joint: Inflammatory Mediators, Treatment, and Long-Term Effects” was commissioned by the editorial office without any funding or sponsorship. N.N.D. served as the unpaid Guest Editor of the series and serves as an unpaid editorial board member of Annals of Joint from August 2022 to July 2024. N.I.K. receives the Consulting fees from Vericel. R.F.L. is a consultant for Ossur, Smith & Nephew, and Responsive Arthroscopy; collects royalties from Ossur, Smith & Nephew, Elsevier, and Arthrex; has research grants from Ossur, Smith & Nephew, AANA, AOSSM; is on the committees for ISAKOS, AOSSM, AANA; and is on the editorial boards for AJSM, JEO, KSSTA, JKS, JISPT, OTSM. The authors have no other conflicts of interest to declare., (2024 Annals of Joint. All rights reserved.)

Anterior cruciate ligament reconstruction (ACLR) with quadriceps tendon (QT) was first described decades ago. Recent studies have demonstrated superior graft characteristics (diameter, strength, and stiffness) and reduced postoperative morbidity. However, limited instrumentation options currently available to surgeons allow for minimally invasive QT harvest with a bone plug. As an alternative to traditional QT harvest techniques, we describe a surgical technique allowing for minimally invasive QT autograft harvest with a bone plug (QuadVantage Technologies, Inc). This approach can offer technical advantages, including efficiency of graft harvest, reproducibility of procedure, and more consistent graft sizes., (© 2023 The Authors.)

Purpose: To evaluate the efficacy of perioperative gabapentin or pregabalin treatment on postoperative pain and opioid requirement reduction in patients undergoing anterior cruciate ligament reconstruction (ACLR)., Methods: A systematic review of randomized control trials was conducted evaluating the effect of gabapentin or pregabalin on postoperative pain and opioid requirement for patients undergoing ACLR. The primary outcomes assessed were postoperative pain scores and opioid requirements. Secondary outcomes were complications, side effects, dosage, and timing of intervention., Results: The initial search query identified 151 studies and 6 studies were included after full-text articles were reviewed. Three studies investigated the use of gabapentin and three studies investigated pregabalin. All three gabapentin studies reported significantly decreased or equivalent pain scores while also significantly reducing or removing total opioid consumption compared to control groups. Pregabalin demonstrated inconsistent efficacy for pain control and opioid consumption parameters across three studies. One study (pregabalin, n = 1) reported significantly increased incidence of dizziness with pregabalin compared to placebo., Conclusions: There is moderate evidence demonstrating that preoperative gabapentin may be safe and effective in reducing postoperative pain and opioid consumption after ACLR. Gabapentin may be considered when employed as part of a multimodal analgesia regimen; however, the optimal protocol has yet to be determined. Currently, there is limited evidence demonstrating the efficacy of pregabalin on pain and opioid consumption in the setting of ACLR., Level of Evidence: Level I, systematic review of Level I Studies., (Copyright © 2023. Published by Elsevier Inc.)

The goal of a self-assembly tissue engineering is to create functional tissue following a natural cell-driven process that mirrors natural development. This approach to tissue engineering has tremendous potential for the development of reparative strategies to treat musculoskeletal injuries and diseases, especially for articular cartilage which has poor regenerative capacity. Additionally, many bioengineering and culture methods fail to maintain the chondrocyte phenotype and contain the correct matrix composition in the long term. Existing cartilage-engineering approaches have been developed, but many approaches involve complicated culture techniques and require foreign substances and biomaterials as scaffolds. While these scaffold-based approaches have numerous advantages, such as an instant or rapid creation of biomechanical properties, they frequently result in dedifferentiation of cells in part, due to the adherence to foreign scaffold materials. In this chapter, we describe a novel approach of developing a scaffold-less cartilage-like biomaterial, using the simple principle that cells at high density bear a capacity to coalesce when they cannot attach to any culture substrate. We refer to the biomaterial formed as a cartilage tissue equivalent or CTA and have published to describe their characteristics and utility in high-throughput drug screening. The method is described to generate reproducible cartilage analogs using a specialized high-density suspension culture technique using a hydrogel poly-2-hydroxyethyl methacrylate (polyHEMA) coating of a culture dish. We have demonstrated that this approach can rapidly form biomass of chondrocytes that over time becomes very synthetically active producing a cartilage-like extracellular matrix that closely mimics the biochemical and biomechanical characteristics of native articular cartilage. The culture approach can also be used to form CTA from other than articular cartilage-derived chondrocytes as well as mesenchymal stem cells (MSCs) (while differentiating MSCs into chondrocytes). Some of the advantages are phenotype stability, reproducible CTA size, and biomechanical and biochemical characteristics similar to natural cartilage., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: To evaluate the accuracy and precision of postoperative coronal plane alignment using 3D-printed patient-specific instrumentation (PSI) in the setting of proximal tibial or distal femoral osteotomies., Methods: A systematic review evaluating the accuracy of 3D-printed PSI for coronal plane alignment correcting knee osteotomies was performed. The primary outcomes were accuracy of coronal plane limb alignment correction and number of correction outliers. Secondary variables were duration of surgery, number of intraoperative fluoroscopic images, complications, cost, and clinical outcomes (as applicable)., Results: Ninety-three studies were identified, and 14 were included in the final analysis. Overall, mean postoperative deviation from target correction ranged from 0.3° to 1° for all studies using hip-knee angle measurements and 2.3% to 4.9% for all studies using weight-bearing line measurements. The incidence of correction outliers was assessed in 8 total studies and ranged from 0 to 25% (total n = 10 knees) of patients corrected with 3D-printed PSI. Osteotomies performed with 3D-printed cutting guides or wedges demonstrated significantly shorter operative times (P < .05) and fewer intraoperative fluoroscopic images (P < .05) than control groups in four case control studies., Conclusion: Patients undergoing distal femoral osteotomy or proximal tibial osteotomy procedures with 3D-printed patient-specific cutting guides and wedges had highly accurate coronal plane alignment with a low rate of outliers. Patients treated with 3D printed PSI also demonstrated significantly shorter operative times and decreased intraoperative fluoroscopy when compared to conventional techniques., Level of Evidence: Level IV, systematic review of Level III-IV studies., (Copyright © 2022. Published by Elsevier Inc.)

Purpose: To evaluate the efficacy of selective interleukin (IL)-1 inhibitor therapy in the reduction of posttraumatic osteoarthritis (PTOA) progression following knee ligament or meniscal injury., Methods: A systematic review was conducted evaluating the disease-modifying efficacy of selective IL-1 inhibition in the setting of knee PTOA., Results: The literature search identified 364 articles and 11 studies were included (n = 10 preclinical, n = 1 clinical). Drug delivery in preclinical studies was administered using IL-1Ra-encoded helper-dependent adenovirus particles (n = 3), synovial cells transfected with an IL-1Ra-encoded retroviral vector (n = 3), or varying chemical compositions of nonviral microcapsule gene carriers (n = 4). Intervention with selective IL-1 inhibitor therapy within 2 weeks of injury provided the greatest protective benefits in reducing the progression of PTOA regardless of drug delivery methodology in preclinical models. The majority of studies reported significantly better cartilage integrity and reduction in lesion size in animals treated with gene therapy with the greatest effects seen in those treated within 5 to 7 days of injury., Conclusions: Early intervention with selective IL-1 inhibitor therapy were effective in reducing proinflammatory IL-1β levels in the acute and subacute phases following traumatic knee injury in preclinical animal model studies, while significantly reducing cartilage damage, lesion size, and PTOA progression at short-term follow-up. However, it was found that the effect of these therapies diminished over time., Clinical Relevance: Acute, intra-articular injection of selective IL-1 inhibitors may reduce PTOA progression, supporting the need for additional basic and clinical investigation., (Copyright © 2022. Published by Elsevier Inc.)

Purpose: While the association with acute anterior cruciate ligament (ACL) tears has been established, other risk factors and associated pathologies which occur with a concomitant lateral meniscal posterior root tear (LMPRT) are not well defined. The purpose of this study was to compare the risk factors and concomitant pathologies between patients with LMPRT and patients without LMPRTs in the setting of a primary ACL tear., Methods: Patients with a LMPRT identified at the time of primary ACL reconstruction by a single surgeon were identified. These patients were matched by age and sex to patients undergoing primary ACL reconstruction who were not found to have lateral meniscus root tears (control group) in a 1:1 ratio. Lateral posterior tibial slope (PTS), medial PTS, lateral femoral condyle height and depth, lateral tibial plateau depth, and lateral tibial plateau subluxation were measured on MRI. Anteroposterior full-limb alignment radiographs were used to measure the medial proximal tibia angle (MPTA), the mechanical lateral distal femoral angle (mLDFA), and the mechanical weightbearing axis for the injured extremity., Results: One-hundred three patients were included in both the LMPRT group and the matched control group. Patients with a LMPRT had a significantly steeper lateral PTS (9.1° vs. 7.0°, p = 0.001), a steeper medial PTS (7.0° vs. 6.0°, p = 0.03), and a greater lateral-to-medial slope asymmetry (2.0° vs. 1.0°, p = 0.001). There were no differences in lateral femoral condyle depth or height, lateral tibial plateau depth, lateral tibial plateau subluxation, MPTA, mLDFA, or mechanical weightbearing axis between groups. There was a significantly increased incidence of medial meniscus ramp lesions in patients with lateral meniscus posterior root tears compared with controls (34.0% vs. 15.5%, odds ratio: 2.8, p = 0.002). There were no associations with concomitant ligament injuries, medial meniscus root tears, or non-ramp tears based on case/control grouping., Conclusion: In conclusion, LMPRTs in the setting of primary ACL injuries were associated with significantly increased lateral and medial PTSs, and increased asymmetry between lateral and medial PTSs. In addition, clinicians should be aware of the increased incidence of concurrent medial meniscal ramp lesions in patients with LMPRTs. Knowledge of these associations helps guide clinical decision-making and counselling of patients in the setting of ACL tears with concomitant LMPRTs., Level of Evidence: IV., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Objectives: To evaluate the self-reported incidence of sleep disturbances, defined as ≤7 hours of sleep per 24-hour period, in patients undergoing arthroscopic-assisted knee surgery., Methods: Patients who underwent arthroscopic knee surgery over the course of a 4-month period were prospectively included. Patients were excluded if a history of insomnia or other sleep altering medical history was reported. Self-reported sleep metrics included average number of hours of sleep per night, average number of awakenings during sleep per night, perceived quality of sleep, average pain level during sleep and number of hours of physical activity/therapy per week. Data were collected at weeks 1, 3, and 6 postoperatively. Joint circumference was measured on postoperative day 1 and served as an indicator of a knee effusion. Paired t -tests were used to compare preoperative to postoperative hours of sleep. Simple and multiple linear regression were used to evaluate relationships between surgical variables and postoperative sleep metrics., Results: There were 123 patients who underwent arthroscopic knee surgery during the prospective enrolment period; 83 patients were included in the final analysis. The overall incidence of preoperative sleep disturbances was 20% (n=17). The overall incidence of self-reported postoperative sleep disturbances was 99%, 96% and 90% at weeks 1, 3 and 6, respectively. The average number of hours slept was significantly reduced at 1, 3 and 6 weeks postoperatively compared with the preinjury state (p<0.001). Knee joint circumference had a significantly negative correlation with average number of hours of sleep in the first 6 weeks postoperatively ( R =-0.704; p=0.001). Surgical variables including severity of surgery, weekly postoperative pain level and weekly hours of postoperative physical therapy were not significant independent predictors of acute postoperative sleep disturbances (p>0.05)., Conclusion: Sleep disturbances were commonly reported in patients following arthroscopic knee surgery without correction of sleep metrics by 6 weeks postoperatively. The majority of sleep disturbances in this cohort correlated with an increased knee effusion. A multidisciplinary team approach is recommended to counsel patients regarding the potential for and problems with acute sleep disturbances following arthroscopic knee surgery. Level of evidence : 3., Competing Interests: Competing interests: None declared., (© International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To perform a systematic review and meta-analysis of the literature on anterolateral ligament (ALL) reconstruction as it relates to techniques, biomechanical properties, and clinical outcomes., Methods: PubMed, OVID/Medline, and Embase were queried in July 2020. Data pertaining to (1) techniques, (2) biomechanical properties, and (3) clinical outcomes of ALL reconstruction were recorded. DerSimonian-Laird random-effects meta-analyses were performed for included randomized controlled trials comparing combined ALL/anterior cruciate ligament (ACL) reconstruction and isolated ACL reconstruction. Data from lower levels of evidence were described qualitatively, and when possible, outcomes were reported as ranges to avoid inappropriate pooling of data., Results: A total of 46 articles were identified. Sixteen were biomechanical studies, 16 were clinical outcome studies, and 14 were technique studies. Of the 16 biomechanical studies, the majority demonstrated that anterior translation, internal rotation, and pivot shift was restored with combined ACL/ALL reconstruction and superior to ACL reconstruction alone. Ten biomechanical studies reported on constraint: 4 noted overconstraint when the femoral attachment site was proximal and posterior to the lateral femoral condyle, whereas 1 reported laxity. ACL failure rates after combined ACL/ALL reconstruction ranged between 2.7% and 11.1%. The mean postoperative Lysholm score ranged between 58.7 and 98.0; mean postoperative International Knee Documentation Committee score between 57.8 and 96.3; and mean postoperative Tegner score between 4 and 8. Six outcomes were explored through meta-analysis, of which the mean difference in Lysholm scores (2.26, P < .001) and restoration of pivot shift (relative risk 1.1, P = .046) was found to favor combined ACL/ALL reconstruction., Conclusions: Although indications for ALL reconstruction remain heterogeneous, contemporary evidence suggests that ALL reconstruction improves pivot shift and confers comparable clinical and functional outcomes with isolated ACLR., Level of Evidence: IV, systematic review and meta-analysis., (Copyright © 2021 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To conduct a review of active United States-based clinical trials investigating preventative, symptom resolution, and disease-modifying therapies for osteoarthritis (OA)., Methods: We conducted a review of currently active clinical trials for OA using data obtained from the ClinicalTrials.gov database as of August 2020. The inclusion criteria were active studies registered in the United States that involved the prevention, symptom resolution, or disease modification of OA. Descriptive statistics were recorded and summarized., Results: A total of 3,859 clinical trials were identified, and 310 were included in the final analysis. Of the currently active trials, 89% (n = 275) targeted symptom resolution in patients with existing OA, 6% (n = 19) targeted OA disease-modifying therapeutics, and 5% (n = 16) targeted the prevention of OA in high-risk patients (P < .001). Primary interventions included medical devices (44%, n = 137), pharmaceutical drugs (14%, n = 42), surgical procedures (14%, n = 42), cellular biologics (13%, n = 41), and behavioral therapies (13%, n = 41). There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs (30% vs 14%) (P = .015). Most trials targeted the knee joint (63%, P = .042), with 38% of all trials evaluating joint arthroplasty. There were no significant differences between private sector and government funding sources (43% and 49%, respectively) (P = .288), yet there was a significantly lower rate of funding from industry (8%) (P = .026)., Conclusions: There was a significantly higher number of clinical trials investigating symptomatic resolution therapy (89%) for existing OA in comparison to preventative (5%) and disease-modifying (6%) therapies. The most common interventions involved medical devices and joint replacement surgery, with the knee joint accounting for more than 60% of the current clinical trials for OA. There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs. Funding of clinical trials was split between the private sector and government, with a low rate of reported funding from industry partners., Clinical Relevance: Identifying existing needs in the current market may help increase rates of research funding or optimize current funding pathways, in this study, specifically for targeting unaddressed focus areas in OA research. Our systematic review highlights the potential need for additional research and development regarding OA preventative and disease-modifying therapies., (Copyright © 2021 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to evaluate the main focus areas for research and development for furthering the state of meniscus science in 2021., Methods: An electronic survey including 10 questions was sent in a blind fashion to the faculty members of the 5 th International Conference on Meniscus Science and Surgery. These faculty served as an expert consensus on the future of research and development areas of meniscus science. Survey responses were analyzed using descriptive statistics and ranking weighted averages were calculated to score survey questions., Results: Of the 82 faculty, 76 (93%) from 18 different countries completed the survey (84% male, 16% female). The highest ranked future research and development focus areas were meniscus repair, biologics, osteotomy procedures, addressing meniscus extrusion, and the development of new therapies for the prevention of posttraumatic osteoarthritis. Currently, the most 'valuable' type of biologic reported for meniscus treatment was platelet-rich plasma. The main reported global research limitation was a lack of long-term clinical outcomes data. The most promising emerging medical technologies for improving meniscus science were 3-D printing, personalized medicine, and artificial implants., Conclusions: This survey suggests that the future of meniscus science should be focused on meniscal preservation techniques through meniscus repair, addressing meniscal extrusion, and the use of orthobiologics. The lack of long-term clinical outcomes was the main reported research limitation globally for meniscus treatment. Future product development utilizing emerging medical technologies suggest the use of 3-D printing for meniscal transplants/scaffolds, personalized treatment, and bioengineering for artificial implants., Level of Evidence: Level V.

Purpose: To compare varus knee stability and clinical outcomes between patients who underwent fibular collateral ligament reconstruction (FCLR) or lateral collateral ligament (LCL) reconstruction with autografts versus allografts when undergoing concomitant anterior cruciate ligament reconstruction (ACLR)., Methods: All patients who underwent primary ACLR and concomitant FCLR from 2010 to 2017 performed by a single surgeon (R.F.L.) were retrospectively identified. Clinical characteristics and graft choices for FCLR were collected. Patients with a minimum 2-year follow-up for clinical outcome scores and 6-month stress radiographs were included. Patients with any other ligamentous procedure or revision ACLR were excluded., Results: We identified 69 primary ACLR with concomitant FCLR patients who met the inclusion criteria. Fifty patients underwent FCLR with semitendinosus autografts, and 19 with allografts. There were no significant side-to-side differences (SSDs) in lateral compartment gapping on varus stress x-rays between the 2 cohorts (allograft, 0.49 mm; autograft, 0.15 mm, P = .22), and no FCLR failures. There were no significant differences between autograft and allograft groups at minimum 2-year outcomes for 12-Item Short Form mental or physical composite score (SF12 MCS, P = .134; SF12 PCS, P = .642), WOMAC total (P = .158), pain (P = .116), stiffness (P = .061), or activity (P = .252); International Knee Documentation Committee (IKDC) (P = .337), Tegner (P = .601), Lysholm (P = .622), or patient satisfaction (P = .218). There were no significant differences in clinical knee stability between groups at an average follow-up of 3.6 years (P = 1.0)., Conclusion: There were no differences in varus stress laxity 6 months postoperatively or clinical outcome scores at ≥2 years postoperatively between patients having FCL reconstructions with either autograft or allograft. This study demonstrates that both hamstring autografts and allografts for FCL reconstructions offer reliable and similar radiographic and clinical results at short-term follow-up., Level of Evidence: III, retrospective comparative trial., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: To evaluate the association between social distancing quantified by mobile phone data and the current prevalence of COVID-19 infections in the U.S. per capita., Methods: Data were accessed on April 4, 2020, from Centers for Disease Control and Prevention, Google COVID-19 Community Mobility Report, and the United States Census Bureau to report prevalence of COVID-19 infections, mobility data, and population per state, respectively. Mobility data points were defined as daily length of visit or time spent in a single location based on mobile phone users shared locations from February 7 - March 29, 2020. Multivariable linear regression was used to evaluate relationships between normalized per capita infection prevalence and six parameters of social distancing., Results: Mobility data indicated the following percent changes compared to median values of baseline activity: -50% in transit stations, -45% in retail/recreation, -36% in workplaces, -23% in grocery/pharmacy, -19% in parks, and +12% in residential living areas. Multivariable linear regression revealed significant correlation between prevalence of infection per capita and parameters of social distancing ( R = 0.604, P= 0.002 ). Time at home was not an independent predictor for prevalence of infection per capita (beta= 0.016; 95% CI, -0.003 to 0.036; P= 0.09 )., Conclusion: Based on mobility reports from mobile phone GPS data and six characteristics of social distancing, significant associations were identified between geographic activity and prevalence of COVID-19 infections in the U.S. per capita. Mobile phone data utilizing 'location history' may be warranted to monitor the effectiveness of social distancing parameters on reducing prevalence of COVID-19 in the U.S.

Stress radiographs can provide an objective, quantifiable assessment of ligamentous knee injury. Commonly utilized techniques include varus, valgus, and posterior stress radiographs and can be used to augment findings on physical examination and magnetic resonance imaging. Both in vitro and in vivo studies have demonstrated reliability and validity of stress radiographs for diagnosing isolated and multiple ligament knee injuries. Varus stress radiographs are clinician applied at 20° flexion to detect injuries to the fibular collateral ligament and posterolateral corner. Valgus stress radiographs are clinician applied at 20° flexion to detect injuries to the medial collateral ligament or posteromedial corner. To evaluate the posterior cruciate ligament, posterior kneeling stress radiographs are obtained with the patient kneeling at 90° flexion on a firm platform. Bilateral radiographs are obtained and the side-to-side difference is compared to established criteria for injury severity. Stress radiographs support accurate diagnosis of complex knee injuries and also provide an objective measure of knee stability following ligament reconstruction. These imaging techniques can be performed in an ambulatory clinic setting with minimal additional equipment, and are thereby cost-effective, efficient, and support clinical decision-making in the treatment of complex knee injuries., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare posterior tibial slope (PTS) measurements from standard lateral knee radiographs with measurements from full-length lateral tibia radiographs., Methods: We performed a multicenter, prospective study. Lateral knee and full-length lateral tibia radiographs were obtained for each patient, and PTS was measured. Slope measurements were obtained by measuring the angle between an average of the medial and lateral tibial plateaus and a representative tibial diaphysis line. The proximal anatomic axis was measured on lateral knee radiographs, and both the mechanical axis and anatomic axis were measured on full-length lateral tibia radiographs. The mechanical axis was defined as the center of the plateau to the center of the plafond, and the anatomic axis was defined as the center of the tibial diaphysis. The minimal clinically significant difference was defined a priori as 2° of PTS or greater., Results: A total of 140 patients met the inclusion criteria. The average PTS using the proximal anatomic axis was 11.6° ± 3.2° on lateral knee radiographs; the PTS measured on full-length lateral tibia radiographs was 9.5° ± 3.4° using the mechanical axis and 11.8° ± 3.1° using the anatomic axis. There was a significant difference between the measurements with the mechanical axis and both anatomic axis measurements (P < .01) but no significant difference between the 2 anatomic axis measurement techniques (P = .574). In total, 55% of patients (n = 77) had a 2° or greater difference between the proximal anatomic axis and mechanical axis PTS measurement techniques., Conclusions: There was no significant difference between PTS measurements that used the proximal anatomic axis from lateral knee radiographs and those that used the anatomic axis from full-length lateral tibia radiographs. Thus, lateral knee radiographs are adequate to accurately obtain tibial slope measurements. However, there was a significant difference between PTS measurements that used the anatomic axis and those that used the mechanical axis of the tibia., Clinical Relevance: It is recommended that future studies report tibial slope based upon measurements that utilize the anatomic axis in order to ensure that subsequent conclusions are comparable, independent of the radiographic view., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess patient history, physical examination findings, magnetic resonance imaging (MRI) and 3-dimensional computed tomographic (3D CT) measurements of those with anterior cruciate ligament (ACL) graft failure compared with primary ACL tear patients to better discern risk factors for ACL graft failure., Methods: We performed a retrospective review comparing patients who underwent revision ACL reconstruction (ACLR) with a primary ACLR group with minimum 1-year follow-up. Preoperative history, examination, and imaging data were collected and compared. Measurements were made on MRI, plain radiographs, and 3D CT. Inclusion criteria were patients who underwent primary ACLR by a single surgeon at a single center with minimum 1-year follow-up or ACL graft failure with revision ACLR performed by the same surgeon., Results: A total of 109 primary ACLR patients, mean age 33.7 years (range 15 to 71), enrolled between July 2016 and July 2018 and 90 revision ACLR patients, mean age 32.9 years (range 16 to 65), were included. The revision ACLR group had increased Beighton score (4 versus 0; P < .001) and greater side-to-side differences in quadricep circumference (2 versus 0 cm; P < .001) compared with the primary ACLR group. A family history of ACL tear was significantly more likely in the revision group (47.8% versus 16.5%; P < .001). The revision group exhibited significantly increased lateral posterior tibial slope (7.9° versus 6.2°), anterolateral tibial subluxation (7.1 versus 4.9 mm), and anteromedial tibia subluxation (2.7 versus 0.5 mm; all P < .005). In the revision group, femoral tunnel malposition occurred in 66.7% in the deep-shallow position and 33.3% in the high-low position. The rate of tibial tunnel malposition was 9.7% from medial to lateral and 54.2% from anterior to posterior. Fifty-six patients (77.8%) had tunnel malposition in ≥2 positions. Allograft tissue was used for the index ACLR in 28% in the revision group compared with 14.7% in the primary group., Conclusion: Beighton score, quadriceps circumference side-to-side difference, family history of ACL tear, lateral posterior tibial slope, anterolateral tibial subluxation, and anteromedial tibia subluxation were all significantly different between primary and revision ACLR groups. In addition, there was a high rate of tunnel malposition in the revision ACLR group., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess the most common presenting symptoms, clinical outcomes, and satisfaction after anatomic reconstruction of the proximal tibiofibular joint (PTFJ) with a free semitendinosus autograft., Methods: Consecutive patients with minimum 2-year follow-up after isolated anatomic PTFJ reconstruction were retrospectively reviewed. Patients were evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and Lysholm Knee Survey score along with a simple numeric patient satisfaction score (0-10, with 10 rated as perfect). Statistical analysis was performed with paired t tests, with P < .05 considered significant., Results: The study included 16 PTFJ reconstruction surgical procedures in 15 patients with isolated proximal tibiofibular instability verified by an examination under anesthesia (4 reconstructions in male patients vs 12 in female patients); the average age was 37.9 ± 14.6 years, with an average follow-up period of 43.2 months (range, 22-72 months). Of the 13 patients with complete follow-up, 11 (84.6%) were able to return to full desired activities and previous level of sport. Fourteen patients presented with concomitant common peroneal nerve pathology. Two patients had a subsequent complication. No patients needed an additional procedure. Significant (P < .05) improvement occurred across all WOMAC domains and in the WOMAC total score, from 31.4 (±14.9) preoperatively to 15.2 (±15.5) postoperatively. Lysholm Knee Survey scores significantly (P < .05) improved from 51.2 (±17.2) to 75.0 (±18.0). Patients' overall satisfaction was rated 7.6 (± 2.7) of 10., Conclusions: At an average follow-up of 43.2 months, anatomic PTFJ reconstruction for isolated PTFJ instability provided improvement in clinical outcomes, a return to activities, and a low risk of complications or need for additional procedures., Clinical Relevance: PTFJ reconstruction with hamstring tendon graft is a promising surgical treatment that improves patient satisfaction when conservative treatment of PTFJ instability fails., Level of Evidence: Level IV, case series., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the diagnostic accuracy of magnetic resonance imaging and varus stress radiographs for fibular collateral ligament (FCL) tears, and compare these modalities to intraoperative findings., Methods: All patients who underwent an isolated FCL or combined anterior cruciate ligament (ACL)/FCL reconstruction by a single surgeon between 2010 and 2017 with preoperative varus stress radiographs and magnetic resonance imaging (MRI) were included in this study. A control group was composed of patients with an MRI and intact ACL and FCL. Sensitivity and specificity of diagnosing FCL injuries on MRI were determined based on review by a fellowship-trained musculoskeletal radiologist, blinded to the pathology associated with each patient (FCL injury vs control), and compared with the gold standard of examination under anesthesia, followed by surgical confirmation of an FCL tear at the time of FCL reconstruction. The sensitivity of diagnosing an FCL injury based on varus stress radiographs was also determined. Furthermore, the ability of both imaging modalities to identify an FCL injury was stratified based on acute versus chronic etiology., Results: A total of 232 patients were included: 98 patients in the FCL tear group (mean age: 33.6 ± 12.2 years) and 134 patients in the control group (mean age: 44.0 ± 17.2 years). Varus stress radiographs were determined to be more sensitive in diagnosing FCL injuries compared with MRI, with an overall sensitivity of 70% compared with 66%, respectively. Based on MRI, overall specificity was 68%. Based on chronicity of the injuries, MRI was more accurate for detecting acute FCL injuries than chronic injuries (P = .002), and varus stress radiographs were more accurate for detecting chronic FCL injuries than acute injuries (P = .041)., Conclusions: The results support the use of both varus stress radiographs and MRI in diagnosing FCL injuries, because MRI is more sensitive in diagnosing an acute FCL tear, and varus stress radiographs are more sensitive in diagnosing a chronic FCL tear. Both imaging modalities are recommended to diagnose both acute and chronic FCL injuries., Level of Evidence: Level II, case-control study., (Copyright © 2018 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To determine the exact value of side-to-side difference (SSD) in heel height that was associated with combined anterior cruciate ligament (ACL) and fibular collateral ligament (FCL) tears (compared with an isolated ACL tear) and determine the clinical utility of heel height SSD in the assessment of this injury pattern., Methods: Two patient groups were identified: (1) patients with isolated ACL tears and (2) patients with combined ACL-FCL tears but without additional collateral or cruciate ligament injuries. Determination of the amount of the heel height SSD was determined during the outpatient clinic visit. Receiver operator characteristic curves were used to evaluate the accuracy of diagnostic tests by plotting the true-positive (sensitivity) rate against the false-positive (1-specificity) rate at various thresholds. In addition, magnetic resonance imaging (MRI) reports were reviewed to calculate the sensitivity of MRI for the detection of FCL injury. MRI sensitivity was then compared with the sensitivity of the heel height examination., Results: One hundred and fifty-eight patients (71 men, 87 women) in the isolated ACL tear patient group and 117 patients (60 men, 57 women) in the combined ACL-FCL tear patient group were reviewed. A 3-cm or greater SSD was found in 13 of the 158 (8.2%) isolated ACL tear patients and 84 of the 117 (72%) ACL-FCL tear patients. The sensitivity, specificity, positive predictive value, and negative predictive value of the heel height test were 72%, 92%, 86%, and 86%, respectively. The area under the receiver operator characteristic curve was found to be 0.876. After review of all preoperative MRI musculoskeletal radiology reports for patients in the ACL-FCL patient group, a sensitivity of 48% was found., Conclusions: The clinical heel height test resulted in high sensitivity and excellent specificity for the diagnosis of combined ACL-FCL tears compared with the sensitivity and specificity of the MRI detection of FCL injury. The information presented in the current study will improve diagnostic ability through a simple physical examination and avoid missed injuries that are known to compromise surgical outcomes., Level of Evidence: Level III, cross-sectional., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Femoral shaft fractures are common injuries with an incidence of 37.1 per 100,000 person-years in the United States. Retrograde femoral nailing is an increasingly used treatment strategy to manage these injuries, particularly in fractures below stemmed hip prostheses, in supracondylar or distal femur fractures, in fractures in pregnant or obese patients, and when concomitant ipsilateral acetabular/pelvic ring fractures are present. Retrograde fixation has been shown to be a viable option with union rates comparable to antegrade intramedullary nailing. Despite having excellent results in the treatment of femoral fractures, retrograde femoral nails have been associated with iatrogenic patellofemoral chondral damage that may occur because of malpositioning of the intramedullary nail at the entry point. The objective of this case report is to describe 2 patients who suffered iatrogenic trochlear chondral defects after retrograde femoral nailing and subsequently underwent osteoarticular allograft transplantation surgery., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the treatment options, outcomes, and complications associated with proximal tibiofibular joint (PTFJ) instability, which will aim to improve surgical treatment of PTFJ instability and aid surgeons in their decision making and treatment selection., Methods: A systematic review was performed according to Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Inclusion criteria were as follows: PTFJ instability treatment techniques, PTFJ surgical outcomes, English language, and human studies. Exclusion criteria were cadaveric studies, animal studies, basic science articles, editorial articles, review articles, and surveys. Furthermore, we excluded studies that did not report patient follow-up time and studies without any patient-reported, clinical or radiographic outcomes at the final follow-up., Results: The systematic review identified 44 studies (96 patients) after inclusion and exclusion criteria application. For the treatment of PTFJ instability, there were 18 studies (35 patients) describing nonoperative management, 3 studies (4 patients) reported on open reduction, 11 studies (25 patients) reported on fixation, 4 studies (10 patients) that described proximal fibula resection, 3 studies (11 patients) reported on adjustable cortical button repair, 2 studies (3 patients) reported on ligament reconstructions, and 5 (8 patients) studies reported on biceps femoris tendon rerouting. The most (77% to 90%) PTFJ dislocations and instability were anterolateral/unspecified anterior dislocation or instability. Improved outcomes after all forms of PTFJ instability treatment were reported; however, high complication rates were associated with both PTFJ fixation (28%) and fibular head resection (20%)., Conclusions: Improved outcomes can be expected after surgical treatment of PTFJ instability. Proximal tibiofibular ligament reconstruction, specifically biceps rerouting and anatomic graft reconstruction, leads to improved outcomes with low complication rates. Nonoperative treatment is associated with persistent symptoms, whereas both fixation and fibular head resection are associated with high complication rates., Level of Evidence: Level IV, systematic review of level IV studies., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)