No Difference Could Be Detected in Clinical Outcomes of 5-Strand and Quadruple Hamstring Autografts of Similar Diameter in Anterior Cruciate Ligament Reconstruction: A Retrospective Cohort Study.

Background: There are few studies examining the clinical outcomes of 5-strand autografts in anterior cruciate ligament reconstruction (ACL-R). Purpose: We aimed to compare the clinical outcomes of ACL-R using 5-strand (5HS) and 4-strand (4HS) hamstring autografts of similar graft diameter to study the potential effects of autograft strand number on clinical outcomes. Methods: Patients who underwent ACL-R from 2013 to 2018 at a single academic institution and received a 4HS or 5HS autograft were included. Exclusion criteria were less than 2-year follow-up and any additional ligamentous reconstruction. Revision ACL-R and cyclops lesions were assessed at a minimum 2 years of postoperative follow-up. Objective measures of ability to return to sport were assessed at 6 months. Results: The mean graft diameters for 4HS (n = 51) and 5HS (n = 23) autografts were 8.3 ± 0.7 mm and 8.4 ± 0.7 mm, respectively. The mean follow-up for the 4HS and 5HS cohorts was 3.0 ± 1.5 years and 3.3 ± 1.3 years, respectively. The 4HS and 5HS cohorts had revision ACL-R rates of 15.7% (8/51) and 8.7% (2/23), respectively. Cyclops lesions occurred in 5.9% of 4HS patients and 13.0% of 5HS patients. We found no statistically significant differences between groups on objective measures of ability to return to sport. Conclusion: This retrospective cohort study detected no difference in revision ACL-R rates, frequency of cyclops lesions, or objective measures of ability to return to sport in patients who received 4HS or 5HS autografts of similar diameter for ACL-R. Further comparative study with larger sample sizes is warranted.

An analysis of the incidence, risk factors, and timing of development of cyclops lesions after anterior cruciate ligament reconstruction.

BACKGROUND: Cyclops lesions are a known complication following anterior cruciate ligament reconstruction (ACLR) with a described incidence between 1.9% to 10.9%. The objective of this study was to identify the incidence, timing, and variables that correlated with development of a cyclops lesion, and if objective functional testing differed between patients with and without cyclops lesions. METHODS: 313 consecutive patients who underwent ACLR and participated in Lower-Extremity Assessment Protocol (LEAP) testing at a single, academic institution were analyzed. Retrospective chart review was performed to identify patient demographic factors, medical comorbidities, and potential peri-operative risk factors. Postoperative functional outcome metrics and patient reported outcomes were collected per the institution's LEAP testing protocol. Binary logistic regression was utilized to identify risk factors for cyclops lesions. Objective functional outcomes and patient reported outcomes were compared between patients with and without cyclops lesions. RESULTS: 23/313 (7.35%) patients developed a cyclops lesion following ACLR, of which 17 (73.91%) were found to be symptomatic. Concomitant meniscal repair correlated with an increased likelihood of developing a cyclops lesion (p = 0.040); no other risk factors significantly differed between cohorts. There were no clinically relevant extension deficits or differences in objective functional performance measures at six months post-operatively between study cohorts. CONCLUSIONS: Concomitant meniscal repair may be associated with the development of cyclops lesions due to restrictive postoperative range of motion protocols; however no other pre- or intra-operative factors demonstrated significant correlation. Presence of a cyclops lesion should be considered with late loss of knee extension after ACLR.

Deficits in Contralateral Limb Strength Can Overestimate Limb Symmetry Index After Anterior Cruciate Ligament Reconstruction.

Purpose: To evaluate whether contralateral limb strength represents a dynamic, rather than static, data point after anterior cruciate ligament reconstruction (ACL-R). Methods: Patients who underwent isolated ACL-R at a single institution were identified. Patients completed an institutional Lower-Extremity Assessment Protocol (LEAP) testing protocol at 6 and 9 months postoperatively. Extension strength and flexion strength of the ipsilateral and contralateral limbs and limb symmetry index (LSI) were compared between the 6- and 9-month testing outcomes. Subgroup analysis compared patients demonstrating less than or greater than 10% change in contralateral limb flexion and extension strength between 6 and 9 months postoperatively. Results: A total of 144 subjects were included in this study. On average, contralateral limb flexion and extension strength increased 2-4% between 6 and 9 months postoperatively. However, the contralateral limb increased >10% from 6 to 9 months in extension and flexion strength in 35/144 (24.3%) and 55/144 (38.2%) of patients, respectively. The cohort with >10% change between 6 and 9 months had significantly weaker contralateral extension and flexion strength at 6 months compared to the cohort that demonstrated <10% change (extension: 2.00 vs 2.39; P < .001; flexion: 0.84 vs 1.08; P < .001), but similar ipsilateral limb performance. Therefore, the >10% change cohort had a significantly greater LSI at 6 months compared to the <10% change cohort (67.3% vs 59.4%; P = .006). No demographic or operative factors correlated with which patients demonstrated >10% flexion or extension strength changes of the contralateral limb. Conclusion: A large percentage of patients demonstrate significant changes in their contralateral limb flexion and extension strength between 6 and 9 months postoperatively that result from an initial contralateral limb strength deficit. This may limit the utility of the contralateral limb as a control for comparison to the operative extremity during return to sport assessment.

Flexible Versus Rigid Reaming Systems for Independent Femoral Tunnel Reaming During ACL Reconstruction: Minimum 2-Year Clinical Outcomes.

Background: Radiographic and cadaveric studies have suggested that anatomic anterior cruciate ligament reconstruction (ACLR) femoral tunnel drilling with the use of a flexible reaming system through an anteromedial portal (AM-FR) may result in a different graft and femoral tunnel position compared with using a rigid reamer through an accessory anteromedial portal with hyperflexion (AAM-RR). No prior studies have directly compared clinical outcomes between the use of these 2 techniques for femoral tunnel creation during ACLR. Purpose: To compare revision rates at a minimum of 2 years postoperatively for patients who underwent ACLR with AM-FR versus AAM-RR. The secondary objectives were to compare functional testing and patient-reported outcomes between the cohorts. Study Design: Cohort study; Level of evidence, 3. Methods: Included were consecutive patients at a single academic institution between 2013 and 2018 who underwent primary ACLR without additional ligamentous reconstruction. Patients were separated into 2 groups based on the type of anatomic femoral tunnel drilling: AM-FR or AAM-RR. Graft failure, determined by revision ACLR, was assessed with a minimum 2 years of postoperative follow-up. The authors also compared patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]) and functional performance testing performed at 6 months postoperatively. Results: A total of 284 (AAM-RR, 232; AM-FR, 52) patients were included. The mean follow-up time was 3.7 ± 1.5 years, with a minimum 2-year follow-up rate of 90%. There was no significant difference in the rate of revision ACLR between the AAM-RR and AM-FR groups (10.8% vs 9.6%, respectively; P = .806). At 6 months postoperatively, there were no significant between-group differences in peak knee extension strength, peak knee flexion strength, limb symmetry indices, or hop testing, as well as no significant differences in IKDC (AAM-RR, 81.1; AM-FR, 78.9; P = .269) or KOOS (AAM-RR, 89.0; AM-FR, 86.7; P = .104). Conclusion: In this limited study, independent femoral tunnel drilling for ACLR using rigid or flexible reaming systems resulted in comparable rates of revision ACLR at a minimum of 2 years postoperatively, with no significant differences in strength assessments or patient-reported outcomes at 6 months postoperatively.

Comparing the Use of Flexible and Rigid Reaming Systems Through an Anteromedial Portal for Femoral Tunnel Creation During Anterior Cruciate Ligament Reconstruction: A Systematic Review.

BACKGROUND: Recent studies have suggested that femoral tunnel drilling during anterior cruciate ligament (ACL) reconstruction (ACLR) with the use of a flexible reaming system through a standard anteromedial portal (AM-FR) may result in a different tunnel geometry compared with a rigid reamer through an accessory anteromedial portal with hyperflexion (AM-RR). PURPOSE: To summarize radiologic, anatomic, and clinical outcomes from available studies that directly compared the use of AM-FR versus AM-RR for independent femoral tunnel creation during ACLR. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A literature search was performed using the MEDLINE (PubMed) and Web of Science databases to identify all studies that directly compared radiologic, anatomic, and clinical outcomes between the use of AM-FR and AM-RR. The literature search, data recording, and methodological quality assessment was performed by 2 independent reviewers. The outcomes analyzed included resultant ACL graft positioning and graft bending angle; femoral tunnel positioning, aperture morphology, length, and widening; posterior wall breakage; and distance from various posterolateral knee structures. RESULTS: A total of 13 studies met the eligibility criteria for inclusion. There was no difference in femoral tunnel aperture location between techniques. There were conflicting findings among studies regarding which technique resulted in a more acute graft bending angle. One study reported greater femoral tunnel widening upon follow-up with the use of AM-FR. AM-FR produced longer and more anteverted femoral tunnels than did AM-RR. The difference in tunnel length was significant and more prominent in lesser degrees of knee flexion. With AM-FR, femoral tunnels were farther from the lateral collateral ligament and peroneal nerve, and 1 of 5 studies had fewer reports of posterior wall breakage. There has been no literature comparing the clinical or functional outcomes of these techniques. CONCLUSION: Although no clinical studies exist comparing AM-FR and AM-RR for femoral tunnel creation during ACLR, both systems allow for reproducible positioning of an anatomic femoral tunnel aperture. The use of AM-FR results in longer and more anteverted femoral tunnels than using AM-RR, with exit points on the lateral femur that are different but safe. Surgeons should be aware of the technical differences with each method; however, further study is needed to identify any clinically important difference that results.

Detection of Osteoarthritis Inflammation by Single-Photon Emission Computed Tomography Based on an Inflammation-Targeting Peptide cFLFLF.

PURPOSE: Although inflammation has been recognized as a key process in the pathogenesis of osteoarthritis (OA), there remains no clinical noninvasive imaging modality that can specifically diagnose inflammatory activity of OA. In this study, a formyl peptide receptor 1 (Fpr1) targeting probe cFLFLF-PEG-HYNIC-99mTc and single-photon emission computed tomography (SPECT) imaging was used to detect inflammatory activity by targeting macrophages involved in the pathogenesis of OA. PROCEDURES: In vitro experiments were performed to evaluate Fpr1 expression during macrophage inflammatory response. In the in vivo studies, anterior cruciate ligament transection (ACLT) surgery was performed, and magnetic resonance imaging (MRI) and histological data were assessed to analyze the OA model in both mice and rats. The radioactive probe cFLFLF-PEG-HYNIC-99mTc and SPECT imaging were used to corroborate OA-related inflammation and compare ACLT vs sham knees. RESULTS: In vitro macrophage activation resulted in a remarkable increase in Fpr1 expression. In vivo experiments in mice and rats produced similar results. MRI and histological analysis demonstrated significant joint degeneration in the ACLT knee. The ACLT knee produced a much stronger signal from the probe when compared to the sham knee. It is important to note that the ratio of ACLT/sham knee signal intensity decreased with OA progression, indicating greater differences earlier in the progression of OA. CONCLUSION: The radioactive probe cFLFLF-PEG-HYNIC-99mTc and SPECT imaging are effective for detecting and monitoring inflammation during OA progression by targeting Fpr1 expression in the knee joint.

Pre-operative Hypoalbuminemia Is Associated with Complications Following Proximal Humerus Fracture Surgery: An Analysis of 919 Patients.

BACKGROUND: Proximal humerus fractures are among the most common presenting fractures to orthopedic surgeons in the USA. Hypoalbuminemia is accepted as a nutrition marker associated with post-operative complications following common orthopedic interventions. QUESTIONS/PURPOSES: Thus, the authors sought to (1) describe the national demographic trends of patients undergoing surgical fixation for proximal humerus fracture and (2) investigate the association between pre-operative hypoalbuminemia, a malnutrition marker, and post-operative complications within 1 year of surgical intervention. METHODS: The PearlDiver Humana Claims Database was queried to identify a nationally representative cohort of patients who underwent surgical intervention for proximal humerus fractures from 2008 to 2015. Demographic and comorbid characteristics were collected. Pearson's χ-squared analysis was used to compare rates of 90-day and 1-year outcomes between hypoalbuminemia (albumin ≤ 3.5 mg/dL) and control groups. Multivariate logistic regression was then used to determine the isolated effect that hypoalbuminemia had on post-operative outcomes. RESULTS: Of the 3337 patients identified, 919 (27.5%) had available serum albumin data. Seventy (7.6%) patients had hypoalbuminemia. Hypoalbuminemia was more likely to be associated with post-operative sepsis (7.1% vs. 1.5%, respectively) and pneumonia (15.7% vs. 4.6) compared with controls. Additionally, hypoalbuminemia was associated with increased 90-day rates of discharge to extended care (4.3% vs. 0.8), emergency room visits (38.6% vs. 21.7), and total cost ($24,051.96 ± 24,972.74 vs. $15,429.74 ± 24,492.30). CONCLUSION: Our study suggests hypoalbuminemia is associated with an increased risk of complications, specifically pneumonia and sepsis, and total health care costs in patients undergoing surgery for proximal humerus fractures. These findings provide insight for individualized patient care that will aid in evaluating the potential risk of surgical complications in an effort to improve outcomes and reduce costs.

Redundant and diverse intranodal pacemakers and conduction pathways protect the human sinoatrial node from failure.

The human sinoatrial node (SAN) efficiently maintains heart rhythm even under adverse conditions. However, the specific mechanisms involved in the human SAN's ability to prevent rhythm failure, also referred to as its robustness, are unknown. Challenges exist because the three-dimensional (3D) intramural structure of the human SAN differs from well-studied animal models, and clinical electrode recordings are limited to only surface atrial activation. Hence, to innovate the translational study of human SAN structural and functional robustness, we integrated intramural optical mapping, 3D histology reconstruction, and molecular mapping of the ex vivo human heart. When challenged with adenosine or atrial pacing, redundant intranodal pacemakers within the human SAN maintained automaticity and delivered electrical impulses to the atria through sinoatrial conduction pathways (SACPs), thereby ensuring a fail-safe mechanism for robust maintenance of sinus rhythm. During adenosine perturbation, the primary central SAN pacemaker was suppressed, whereas previously inactive superior or inferior intranodal pacemakers took over automaticity maintenance. Sinus rhythm was also rescued by activation of another SACP when the preferential SACP was suppressed, suggesting two independent fail-safe mechanisms for automaticity and conduction. The fail-safe mechanism in response to adenosine challenge is orchestrated by heterogeneous differences in adenosine A1 receptors and downstream GIRK4 channel protein expressions across the SAN complex. Only failure of all pacemakers and/or SACPs resulted in SAN arrest or conduction block. Our results unmasked reserve mechanisms that protect the human SAN pacemaker and conduction complex from rhythm failure, which may contribute to treatment of SAN arrhythmias.

Novel application of 3D contrast-enhanced CMR to define fibrotic structure of the human sinoatrial node in vivo.

AIMS: The adult human sinoatrial node (SAN) has a specialized fibrotic intramural structure (35-55% fibrotic tissue) that provides mechanical and electrical protection from the surrounding atria. We hypothesize that late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) can be applied to define the fibrotic human SAN structure in vivo. METHODS AND RESULTS: LGE-CMR atrial scans of healthy volunteers (n olu, 23-52 y.o.) using a 3 Tesla magnetic resonance imaging system with a spatial resolution of 1.0 mm3 or 0.625 × 0.625 × 1.25 mm3 were obtained and analysed. Percent fibrosis of total connective and cardiomyocyte tissue area in segmented atrial regions were measured based on signal intensity differences of fibrotic vs. non-fibrotic cardiomyocyte tissue. A distinct ellipsoidal fibrotic region (length: 23.6 ± 1.9 mm; width: 7.2 ± 0.9 mm; depth: 2.9 ± 0.4 mm) in all hearts was observed along the posterior junction of the crista terminalis and superior vena cava extending towards the interatrial septum, corresponding to the anatomical location of the human SAN. The SAN fibrotic region consisted of 41.9 ± 5.4% of LGE voxels above an average threshold of 2.7 SD (range 2-3 SD) from the non-fibrotic right atrial free wall tissue. Fibrosis quantification and SAN identification by in vivo LGE-CMR were validated in optically mapped explanted donor hearts ex vivo (n ivo, 19-65 y.o.) by contrast-enhanced CMR (9.4 Tesla; up to 90 µm3 resolution) correlated with serial histological sections of the SAN. CONCLUSION: This is the first study to visualize the 3D human SAN fibrotic structure in vivo using LGE-CMR. Identification of the 3D SAN location and its high fibrotic content by LGE-CMR may provide a new tool to avoid or target SAN structure during ablation.