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Scigliano NM, McSweeny KF, Garcia Fleury I, Buckwalter JA. Ulnar Variance in Athletes: A Scoping Review. Sports Health 2024; 16:581-587. [PMID: 37681664 PMCID: PMC11195860 DOI: 10.1177/19417381231195527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023] Open
Abstract
CONTEXT Ulnar variance (UV) is a measurement of the relative locations of the radius and ulna that may become perturbed in athletic populations. Positive UV can be associated with wrist pathologies often treated conservatively or surgically and may result in interruption of sports participation. OBJECTIVE This scoping review aims to summarize diagnostic measures of UV in athletes, describe its relation to separate wrist conditions, and present treatment strategies for symptomatic UV. DATA SOURCES A systematic search was created and modified for PubMed, CINAHL, Embase, and SPORTDiscus including articles from inception until February 2, 2022. STUDY SELECTION Articles including UV characterization, imaging modality style, and an athletic population were searched across multiple databases. STUDY DESIGN A scoping review was designed to identify the methods for imaging UV in athletic populations following the PRISMA Extension for Scoping Reviews (PRISMA-ScR). LEVEL OF EVIDENCE Level 4. DATA EXTRACTION The specific athletic population, imaging modality, measurement style, wrist pathology association, and surgical management of UV were extracted. RESULTS A total of 4321 records were screened independently for eligibility: 22 met inclusion criteria. Eight sports comprised the analysis. All studies referenced conventional radiography to diagnose UV; 50% specified the posteroanterior, 18.2% anteroposterior, and 13.6% pronated, gripping radiographs. Hafner's method (7×), Palmer's technique (2×), and the method of perpendiculars (3×) were used to measure UV. Athletes displayed more positive UV than nonathletes and UV became more positive over time in longitudinal studies. Triangular fibrocartilage complex tears, focal lunate necrosis, and ulnar abutment were associated with positive UV. Ulnar shortening osteotomy was the most performed operation for positive UV. CONCLUSION Conventional radiography is the gold standard for imaging UV in athletes. Hafner's method is the most commonly used radiograph measurement technique. Wrist pathology in athletic populations may indicate positive UV in need for operative management.
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Galvin JW, Milam RJ, Patterson BM, Nepola JV, Buckwalter JA, Wolf BR, Say FM, Free KE, Yohannes E. Periostin Is a Biomarker for Anterior Shoulder Instability: Proteomic Analysis of Synovial Fluid. Am J Sports Med 2024; 52:1719-1727. [PMID: 38702960 DOI: 10.1177/03635465241246258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/06/2024]
Abstract
BACKGROUND The incremental biological changes in the synovial microenvironment of the shoulder in acute and chronic instability that may contribute to joint degeneration are poorly understood. Proteomic analysis of synovial fluid in patients with shoulder instability may improve our understanding of proteins that are shed into shoulder synovial fluid after an injury. HYPOTHESIS Injury-specific factors such as the direction of instability and the severity of glenoid and humeral bone loss are associated with the proteome of synovial fluid in patients with shoulder instability. STUDY DESIGN Descriptive laboratory study. METHODS Synovial fluid lavage samples were compared between patients with anterior (n = 12) and posterior (n = 8) instability and those without instability (n = 5). Synovial proteins were identified with liquid chromatography-tandem mass spectrometry. Orthogonal validation of protein targets found to be significant on tandem mass spectrometry was performed in a separate set of prospective patients with Western blotting. Data were processed and analyzed, and P values were adjusted with the Benjamini-Hochberg method for multiple comparisons. RESULTS A total of 25 patients were included. Tandem mass spectrometry identified 720 protein groups in synovial fluid of patients with shoulder instability. There were 4 synovial proteins that were significantly expressed in patients with anterior instability relative to posterior instability: periostin (POSTN) (adjusted P value = .03; log fold change [logFc] = 4.7), transforming growth factor beta-induced protein ig-h3 (adjusted P value = .05; logFc = 1.7), collagen type VI alpha-3 chain (adjusted P value = .04; logFc = 2.6), and coagulation factor V (adjusted P value = .04; logFc = -3.3). Among these targets, POSTN showed a moderate correlation with the Hill-Sachs lesion size (r = 0.7). Prospective validation with Western blotting confirmed a significantly higher level of POSTN in synovial fluid of patients with anterior instability (P = .00025; logFc = 5.1). CONCLUSION Proteomic analysis enriched our understanding of proteins that were secreted into shoulder synovial fluid of patients with shoulder instability. The identification of POSTN, a proinflammatory catabolic protein involved with tissue remodeling and repair, as a significant target in anterior shoulder instability is a novel finding. Therefore, further study is warranted to determine the role that POSTN may play in the progression of bone loss and posttraumatic osteoarthritis. CLINICAL RELEVANCE Proteomic analysis of synovial fluid in patients with shoulder instability improved our understanding of this abnormality after an injury.
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Hlas A, Ganesh V, Marks J, He R, Salem AK, Buckwalter JA, Duchman KR, Shin K, Martin JA, Seol D. Buffering Mitigates Chondrocyte Oxidative Stress, Metabolic Dysfunction, and Death Induced by Normal Saline: Formulation of a Novel Arthroscopic Irrigant. Int J Mol Sci 2024; 25:1286. [PMID: 38279286 PMCID: PMC10816598 DOI: 10.3390/ijms25021286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
For decades, surgeons have utilized 0.9% normal saline (NS) for joint irrigation to improve visualization during arthroscopic procedures. This continues despite mounting evidence that NS exposure impairs chondrocyte metabolism and compromises articular cartilage function. We hypothesized that chondrocyte oxidative stress induced by low pH is the dominant factor driving NS toxicity, and that buffering NS to increase its pH would mitigate these effects. Effects on chondrocyte viability, reactive oxygen species (ROS) production, and overall metabolic function were assessed. Even brief exposure to NS caused cell death, ROS overproduction, and disruption of glycolysis, pentose phosphate, and tricarboxylic acid (TCA) cycle pathways. NS also stimulated ROS overproduction in synovial cells that could adversely alter the synovial function and subsequently the entire joint health. Buffering NS with 25 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) significantly increased chondrocyte viability, reduced ROS production, and returned metabolite levels to near control levels while also reducing ROS production in synovial cells. These results confirm that chondrocytes and synoviocytes are vulnerable to insult from the acidic pH of NS and demonstrate that adding a buffering agent to NS averts many of its most harmful effects.
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Sanchez PH, Fleury IG, Parker EA, Davison J, Westermann R, Kopp B, Willey MC, Buckwalter JA. Early Versus Delayed Surgery for Midshaft Clavicle Fractures: A Systematic Review. THE IOWA ORTHOPAEDIC JOURNAL 2023; 43:151-160. [PMID: 37383857 PMCID: PMC10296473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Background Orthopaedic surgeons debate the timing of and necessity for surgical intervention when treating displaced midshaft clavicle fractures (MCFs). This systematic review evaluates the available literature regarding functional outcomes, complication rates, nonunion, and reoperation rates between patients undergoing early versus delayed surgical management of MCFs. Methods Search strategies were applied in PubMed (Medline), CINAHL (EBSCO), Embase (Elsevier), Sport Discus (EBSCO), and Cochrane Central Register of Controlled Trials (Wiley). Following an initial screening and full-text review, demographic and study outcome data was extracted for comparison between the early fixation and delayed fixation studies. Results Twenty-one studies were identified for inclusion. This resulted in 1158 patients in the early group and 44 in the delayed. Demographics were similar between groups except for a higher percentage of males in the early group (81.6% vs. 61.4%) and longer time to surgery in the delayed group (4.6 days vs. 14.5 months). Disability of the arm, shoulder, and hand scores (3.6 vs. 13.0) and Constant-Murley scores (94.0 vs. 86.0) were better in the early group. Percentages of initial surgeries resulting in complication (33.8% vs. 63.6%), nonunion (1.2% vs. 11.4%), and nonroutine reoperation (15.8% vs. 34.1%) were higher in the delayed group. Conclusion Outcomes of nonunion, reoperation, complications, DASH scores, and CM scores favor early surgery over delayed surgery for MCFs. However, given the small cohort of delayed patients who still achieved moderate outcomes, we recommend a shared decision-making style for treatment recommendations regarding individual patients with MCFs. Level of Evidence: II.
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Yang L, Martin JA, Brouillette MJ, Buckwalter JA, Goetz JE. Objective evaluation of chondrocyte density & cloning after joint injury using convolutional neural networks. J Orthop Res 2022; 40:2609-2619. [PMID: 35171527 PMCID: PMC9378771 DOI: 10.1002/jor.25295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/01/2021] [Accepted: 02/02/2022] [Indexed: 02/04/2023]
Abstract
Variations in chondrocyte density and organization in cartilage histology sections are associated with osteoarthritis progression. Rapid, accurate quantification of these two features can facilitate the evaluation of cartilage health and advance the understanding of their significance. The goal of this work was to adapt deep-learning-based methods to detect articular chondrocytes and chondrocyte clones from safranin-O-stained cartilage to evaluate chondrocyte cellularity and organization. The U-net and "you-only-look-once" (YOLO) models were trained and validated for identifying chondrocytes and chondrocyte clones, respectively. Validated models were then used to quantify chondrocyte and clone density in talar cartilage from Yucatan minipigs sacrificed 1 week, 3, 6, and 12 months after fixation of an intra-articular fracture of the hock joint. There was excellent/good agreement between expert researchers and the developed models in identifying chondrocytes/clones (U-net: R2 = 0.93, y = 0.90x-0.69; median F1 score: 0.87/YOLO: R2 = 0.79, y = 0.95x; median F1 score: 0.67). Average chondrocyte density increased 1 week after fracture (from 774 to 856 cells/mm2 ), decreased substantially 3 months after fracture (610 cells/mm2 ), and slowly increased 6 and 12 months after fracture (638 and 683 cells/mm2 , respectively). Average detected clone density 3, 6, and 12 months after fracture (11, 11, 9 clones/mm2 ) was higher than the 4-5 clones/mm2 detected in normal tissue or 1 week after fracture and show local increases in clone density that varied across the joint surface with time. The accurate evaluation of cartilage cellularity and organization provided by this deep learning approach will increase objectivity of cartilage injury and regeneration assessments.
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Parker EA, Meyer AM, Garcia Fleury I, Buckwalter JA. Menstrual hormone-induced cyclic thumb CMC instability and degeneration in women: a systematic review. Biol Sex Differ 2022; 13:32. [PMID: 35725646 PMCID: PMC9208132 DOI: 10.1186/s13293-022-00438-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/30/2022] [Indexed: 12/05/2022] Open
Abstract
Background Relaxin is a hormone which peaks during the luteal phase of the menstrual cycle, and a known collagenolytic promoter that has been shown to avidly bind tissues supporting the trapeziometacarpal (TMC) joint in women. We hypothesize a causal linkage between cyclic binding of relaxin to the supporting tissues of the female TMC joint; and to the earlier onset of more severe TMC osteoarthritis (OA) commonly seen in women. Methods A systematic literature review was performed per PRISMA guidelines, qualitatively and quantitatively assessing papers regarding relaxin–TMC joint stability interactions. The primary outcome variable was TMC joint degeneration/loss of function; the “late stage” consequences of relaxin-induced instability. The secondary outcome variable was presence of early signs of relaxin-induced instability; specifically asymptomatic TMC joint laxity in young women. Results In healthy young women, menstrual cycle relaxin peaks corresponded with asymptomatic TMC joint instability. Immunohistochemical studies of TMC arthroplasty patients showed avidly increased relaxin binding to supporting tissues around the TMC joint in women but not men. Demographic analysis of patients from the TMC arthroplasty studies show a predominantly female cohort, who were on average significantly younger than the male surgical patients. Conclusions Each relaxin peak during the menstrual cycle can target receptors on the soft tissues supporting the TMC joint, including—critically—the main stabilizing ligament: the anterior oblique. The cyclic instability is typically asymptomatic for years after menarche, but causes cumulative chondral microtrauma. This likely causes the early-onset, high severity TMC joint OA clinically pervasive among female patients at orthopedic hand clinics. Further research is indicated to develop risk assessment strategies and potential interventional options before and after the onset of hormonal laxity-induced OA. It is widely recognized among hand surgeons that female patients present at a younger age for basal thumb osteoarthritis, with more severe degeneration. The little-known menstrual hormone relaxin, which peaks every ovulatory cycle, may be responsible for the female predominance of this pathology. The soft tissue support structures for the thumb are known to express relaxin receptors which, when activated, trigger lysis of collagen and other extracellular matrix components. Laxity in soft tissues supporting the thumb, such as the deep anterior oblique ligament, would result in joint instability and microtrauma. If women cyclically experience thumb instability and cumulative cartilage microtrauma from menarche through menopause, the female propensity to develop TMC arthritis is aptly justified.
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McIlrath MD, Welsh K, Garcia Fleury I, An Q, Buckwalter JA. The Rurality of Lower Extremity Firearm Injuries. THE IOWA ORTHOPAEDIC JOURNAL 2022; 42:97-101. [PMID: 35821948 PMCID: PMC9210435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
BACKGROUND To highlight the unique spectrum of lower extremity firearm injuries seen at a rural, Midwestern level 1 trauma center to provide insight into prevalence, mechanism of injury, and identify modifiable factors that contribute to firearm injuries of the lower extremity. It is our belief that the creation of our database will help future trauma and firearm databases improve documentation and understand the relationship between anatomic location of injury and outcomes. METHODS A retrospective review of lower extremity firearm injuries from a rural, Midwestern level 1 trauma center was collected from January 2011 to December 2019. Data acquired included injury description; demographics, injury mechanism/ description/ location, firearm used, toxicology, and information regarding hospitalization. Data was analyzed using Chi-squared analysis and Fisher's exact test for categorical data and the Wilcoxon rank sum test for continuous data. RESULTS 69 patients with lower extremity firearm injuries were identified. Average age was 30.14 years, 89.86% were males, and one fatality were identified. 47.83% (33) of these injuries were assaults, followed by unintentional injuries at 42.03% (29). Law enforcement-related and self-inflicted injuries contributed minimally. Handguns were the most common type of firearm, used in 72.5% of cases. Nearly 1/3 of the unintentional firearm injuries occurred during November or December, the active deer hunting months in the community of study. CONCLUSION The lower extremity is uniquely vulnerable to both assaults and unintentional injury in our rural environment, differing from what we have previously published regarding the upper extremity. Lower extremity gunshot wounds increased during the winter months, offering a correlation to deer hunting season. Our findings display that not all firearm injuries are created equal, and that there is a need to improve documentation of and additional study in order to optimally tailor firearm prevention measures based on the ruralityurbanicity spectrum. Level of Evidence: III.
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Buckwalter JA, Lawrence Marsh J, Wynn M, Nickols K. 2022 Dedication of the Iowa Orthopedic Journal: Professor Jose A. Morcuende. THE IOWA ORTHOPAEDIC JOURNAL 2022; 42:v. [PMID: 35821923 PMCID: PMC9210400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
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Kesler K, Buckwalter JA. Efficiency Benefits of Live Fluoroscopy in Hand Clinics. THE IOWA ORTHOPAEDIC JOURNAL 2022; 42:118-121. [PMID: 36601224 PMCID: PMC9769344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Background Postoperative imaging protocols for common hand procedures typically consist of 2-3 plain radiographs at defined intervals dependent on the surgery. Radiographs typically verify reduction, hardware position, and/or evaluate for complications, but also generate costs and alterations in clinic flow. We hypothesize the use of mini-fluoroscopic images will provide comparable clinical data with less cost and improved clinic flow. The objectives of the study were to determine if clinic-based fluoroscopic imaging is feasible for post-operative hand patients and if fluoroscopic imaging results in improved clinic flow (less waiting and more time with provider) and theoretical cost savings using mini-fluoroscopy instead of traditional radiographs. Methods With institutional review board exemption, the prospective use of mini-fluoroscopic evaluation of post-operative hand surgery patients was compared to traditional radiographs using time-based cohort analysis. Patients who underwent percutaneous pinning of phalanges/metacarpals, ORIF (open reduction and internal fixation) of phalanges/metacarpals or ORIF of distal radius fractures were included to evaluate common hand surgery patients. Each cohort consisted of a 3-month data collection period with prospective measures of clinic flow (wait times, appointment times, time with provider) and estimated cost compared between the groups. Results 24 patients met inclusion criteria for data analysis; 11 patients in the mini-fluoroscopy group and 13 patients in the traditional radiograph group. Appointments using mini-fluoroscopy were 24 minutes shorter (53 vs 77 minutes) from patient check-in to check out time. Check-in time to rooming was 10 minutes quicker (9 vs. 19 minutes) using mini-fluoroscopy. Traditional hand radiographs have a face-value of $734 per appointment/series for a total theoretical savings of $9540 (n=13). Conclusion The use of mini-fluoroscopy during orthopedic hand surgery post-operative visits provides a feasible, quick, cost effective way to evaluate patients postoperatively, ultimately, resulting in quicker patient appointments and greater time spent with providers. Level of Evidence: III.
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Ding L, Zhou C, Zheng H, Wang Q, Song H, Buckwalter JA, Martin JA. Migrating Progenitor Cells Derived From Injured Cartilage Surface Respond to Damage-Associated Molecular Patterns. Cartilage 2021; 13:755S-765S. [PMID: 34636628 PMCID: PMC8804768 DOI: 10.1177/19476035211049559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/30/2021] [Accepted: 09/05/2021] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVE To delineate the response of migrating chondrogenic progenitor cells (CPCs) that arose from the surface of mechanically injured articular cartilage to proinflammatory damage-associated-molecular-patterns (DAMPs). DESIGN Bovine CPCs and non-CPC chondrocytes isolated from either impacted or scratched articular cartilage were studied. Those 2 types of cells were treated with mitochondrial DAMPs (MTDs; 10 nM fMLF and 10 µg/mL CpG DNA), or 10 nM HMGB1, or 10 ng/mL IL-1b for 24 hours. At the end of experiments, conditioned media and cell lysates were collected for analysis of expression levels of matrix metalloproteinases (MMPs), chemokines, and cytokines that are associated with cartilage degeneration with Western blotting and quantitative polymerase chain reaction. The difference of expression levels was compared by Welch's t-test. RESULTS Our data indicated that HMGB1 and MTDs remarkably upregulated pro-MMP-13 expression in CPCs. Compared with non-CPCs, CPCs expressed significantly more baseline mRNAs of MMP-13, CXCL12, and IL-6. MTDs greatly increased the expression of MMP-13 and IL-6 in CPCs by over 100-fold (P < 0.001). MTDs also significantly increased IL-8 expression in CPCs to a similar extent (P < 0.001). However, when IL-1b was present, CPCs expressed less MMP-3 and active MMP-13 proteins as well as less CCL2 and IL-6 than did non-CPCs. CONCLUSIONS We concluded that CPCs were more sensitive than non-CPCs in response to DAMPs, especially MTDs. The proinflammatory nature of CPCs implied their critical role in the early phase of posttraumatic osteoarthritis development.
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Wilson ES, Buckwalter JA, Henning G, Davison J, Fleury IG, Willey MC. Inclusion of Olecranon Osteotomy With the Posterior Approach for Fixation of Distal Humerus Fractures (OTA/AO 13) Does Not Increase Surgical Complications. J Orthop Trauma 2021; 35:e223-e227. [PMID: 33208714 DOI: 10.1097/bot.0000000000002006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/03/2020] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To determine if inclusion of an olecranon osteotomy to the posterior paratricipital approach for operative fixation of distal humerus fractures significantly affects surgical complication rates (OTA/AO 13). DESIGN Retrospective comparative cohort study. SETTING Level 1 trauma center. PATIENTS/PARTICIPANTS Three hundred four patients underwent open reduction internal fixation of a distal humerus fracture between 2007 and 2017. Of those, 134 met inclusion criteria (≥15 years, OTA/AO fracture type 13A, B, or C, and posterior surgical approach) for the study (n = 64 with olecranon osteotomy; n = 70 without olecranon osteotomy). INTERVENTION Open reduction internal fixation of distal humerus fractures performed using a posterior paratricipital approach with or without olecranon osteotomy. MAIN OUTCOME MEASURE Ulnar neuropathy (UN), fracture site bony nonunion, and surgical site infection (SSI). RESULTS Thirty-one (33.3%) who underwent the paratricipital approach without olecranon osteotomy, and 15 patients (26.8%) who underwent olecranon osteotomy reported postoperative UN with no significant difference between approaches (P = 0.438). There was no significant difference in rates of SSI (P = 0.418) or fracture site nonunion (P = 0.263) when comparing the approaches. Subjects with Charlson comorbidity index ≥2 were more likely to not undergo an olecranon osteotomy (P = 0.01), whereas subjects with more complex fractures by OTA/AO classification were more likely to have an olecranon osteotomy approach (P = 0.001). CONCLUSIONS Addition of an olecranon osteotomy with the paratricipital approach for fixation of distal humerus fractures does not result in higher rates of UN, fracture site nonunion, or SSI. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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Buckwalter JA. In Bicortical Fracture of the Scaphoid Waist, Early Fixation and Initial Cast Immobilization Did Not Differ for Wrist Pain and Disability at 52 Weeks. J Bone Joint Surg Am 2021; 103:932. [PMID: 33735150 DOI: 10.2106/jbjs.21.00244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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McIlrath MD, Fleury IG, An Q, Buckwalter JA. The Rurality of Upper Extremity Firearm Injuries. THE IOWA ORTHOPAEDIC JOURNAL 2021; 41:171-176. [PMID: 34552421 PMCID: PMC8259192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
BACKGROUND To highlight the unique spectrum of hand and upper extremity firearm injuries seen at a rural, Midwestern level 1 trauma center and identify modifiable factors that contribute to firearm injuries of the hand and upper extremity. METHODS A retrospective review of upper extremity firearm injuries from a rural, Midwestern level 1 trauma center was collected from January 2002 to December 2019. Data acquired included injury description, demographics, injury mechanism/description/location, firearm used, toxicology, and information regarding hospitalization. Data was analyzed using Chi-squared analysis and Fisher's exact test for categorical data and the Wilcoxon rank sum test for continuous data. RESULTS 55 patients with upper extremity firearm injuries were identified. Average age was 33.3 ± 13.0 years, 81.8% were males, and zero fatalities were identified. 58% (38) of these injuries were unintentional firearm injuries, followed by assaults at 34.6% (19). Law enforcement-related and self-inflicted injuries contributed minimally. Handguns were the most common type of firearm, used in 43.6% of cases. 7.3% (4) of injuries occurred while hunting, with 21.8% (12) total during November or December, the active deer hunting months. 92.7% (51) of all firearm injuries presented with fracture, among which 92.2% (47) met a Gustilo-Anderson classification score of at least 3A. Alcohol was detected in 20% (11) of the patients, while other drugs of abuse were detected in 36.4% (20). CONCLUSION Our data suggests that upper extremity firearm injuries in a rural population are unique from urban injuries in that they are predominately unintentional, isolated, and non-fatal. We identify a distinct rural cohort that may benefit from better directed interventions to prevent firearm injuries and ultimately guide firearm education and public policy.Level of Evidence: III.
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Wang KL, Zhang ZQ, Buckwalter JA, Yang Y. Supermicrosurgery in fingertip defects-split tibial flap of the second toe to reconstruct multiple fingertip defects: A case report. World J Clin Cases 2019; 7:2562-2566. [PMID: 31559293 PMCID: PMC6745310 DOI: 10.12998/wjcc.v7.i17.2562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 06/27/2019] [Accepted: 07/20/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Injuries to multiple fingertips pose a significant treatment dilemma. Numerous reconstructive options exist, all with the ultimate goal of restoring function and sensibility to the injured fingertips.
CASE SUMMARY A 24-year-old male suffered injury to multiple fingertips of the right hand, resulting in exposed distal phalanges of the middle, ring, and small fingers. The amputated distal stumps were not possible for replantation. Free flap coverage was selected in order to achieve better functional outcome. The fingertip defects were covered by performing a right second toe split tibial flap using local anesthesia at the harvest site and brachial plexus nerve block for the right upper extremity. At 6-month follow-up, all three of the reconstructed fingertips had some preserved nail growth, Semmes-Weinstein Monofilaments testing was equal to the contralateral side and the Static Two-Point Discrimination were comparable to the contralateral side.
CONCLUSION This report provides a novel reconstructive option for the management of multiple fingertip injuries and demonstrates the utility of supermicrosurgery in management of these injuries.
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Gholson JJ, Shah AS, Buckwalter JA, Buckwalter JA. Long-Term Clinical and Radiographic Follow-Up of Preaxial Polydactyly Reconstruction. J Hand Surg Am 2019; 44:244.e1-244.e6. [PMID: 30853062 DOI: 10.1016/j.jhsa.2018.05.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/21/2018] [Accepted: 05/25/2018] [Indexed: 02/02/2023]
Abstract
PURPOSE The purpose of the study was to determine the long-term results of preaxial polydactyly reconstruction through evaluating strength, range of motion, pain, arthritis, and functional outcomes. METHODS Patients having preaxial polydactyly reconstruction 15 to 60 years ago completed the Disabilities of the Arm, Shoulder, and Hand (DASH) and the Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity (UE) Computer Adaptive Test (CAT). Aggregate scores were compared with those of the general population. Patients completed a clinical evaluation comprising grip strength, pinch strength, side pinch strength, and range of motion. Mean strength and range of motion were compared with the contralateral extremity. Patients had radiographs of the reconstructed thumb to evaluate for arthritis. RESULTS Twenty-five patients, comprising 27 surgical reconstructions, completed patient-reported outcomes questionnaires, and 13 reconstructions underwent clinical and radiographic evaluation. The median follow-up was 36 years. The most common Flatt-Wassel classification was type IV. The mean DASH score was 3.7, similar to the general population mean of 10.1 (SD, 14.5). The mean PROMIS UE CAT score was 51.5, similar to the general population mean of 50 (SD, 10.0). The mean pinch strength, side pinch strength, and grip strength did not differ significantly from the contralateral extremity. There was significantly decreased range of motion at the interphalangeal joint. No patient had pain in the thumb or hand on clinical evaluation. A minority of patients developed radiographic evidence of interphalangeal joint arthritis (15.4%). Nearly half of patients, 46.2%, had angular deformity. CONCLUSIONS Preaxial polydactyly reconstruction patients have functional outcomes similar to the general population, despite decreased range of motion at the interphalangeal joint. Patients have maintained pinch strength, side pinch strength, and grip strength. Radiographic findings of arthritis were seen in 15% of patients at follow-up but none of these patients had associated pain. Late angular deformity developed in nearly half of patients, and this highlights the importance of close follow-up until skeletal maturity. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.
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Carender CN, Buckwalter JA, Glass NA, Westermann RW. Descriptive Epidemiology and Return to Sport After Hand Fractures in NCAA Athletes. THE IOWA ORTHOPAEDIC JOURNAL 2019; 39:49-54. [PMID: 32577107 PMCID: PMC7047303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
BACKGROUND Metacarpal and phalanx fractures are common among professional athletes. There is a paucity of data to guide team physicians on expected return to play after hand fractures. The purpose of this study was to examine the epidemiology and return to play times after hand fractures in NCAA athletes. We hypothesized that surgical management of fractures may expedite return to play times. METHODS The NCAA Injury Surveillance Program database was queried for metacarpal and phalanx fractures during the 2009-2014 seasons in all sports. Injury rates per 100,000 athleteexposures (AEs) were calculated. Student's t-test, Wilcoxon Rank sum tests, Chi-Squared tests, and Fisher Exact Test were used. Statistical significance was set to p<0.05. RESULTS Sports with the highest rates of phalanx and metacarpal fractures included Men's Football, Men's Ice Hockey, Men's Wrestling, and Women's Field Hockey. Multiple sports had participants with no hand fractures over the study period. Male student-athletes with metacarpal fractures treated operatively returned to play at a mean of 31.8±29.4 days versus 13.8±23.6 days for those treated non-operatively. 92% of male student-athletes were able to return to sport in the same season without operative management versus 67% with operative management. Female student-athletes had a cohort too small for statistical analysis. Return to play times for male student-athletes with phalanx fractures were not significantly different between operative and non-operative groups (16.1±21.5 days versus 7.1±13.3 days). CONCLUSIONS Hand fractures are relatively common among NCAA student-athletes participating in contact sports. Student-athletes with metacarpal fractures returned to play at an average of 2-4 weeks after injury; those with phalanx fractures returned at an average of 1-2 weeks. The return to play times illustrated within this study can be used to counsel athletes, athletic trainers, and coaches.Level of evidence: IV.
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Tofte JN, Anthony CA, Polgreen PM, Buckwalter JA, Caldwell LS, Fowler TP, Ebinger T, Hanley JM, Dowdle SB, Holte AJ, Arpey NC, Lawler EA. Postoperative care via smartphone following carpal tunnel release. J Telemed Telecare 2018. [PMID: 30428766 DOI: 10.1177/1357633x18807606.] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION This study explores a novel smartphone application for postoperative care following carpal tunnel release (CTR). We hypothesized that a software-based 'virtual visit' for CTR could be safe, effective and convenient for the patient. METHODS Our group developed the software application utilized in this study. Interactive steps with video instructions enabled patients to complete dressing and suture removal, capture a wound photo, answer a question about median nerve symptoms and capture a video of finger range of motion. Adult patients undergoing endoscopic or open CTR were enrolled. Prior to their scheduled postoperative visit, patients received and completed the module using their smartphone. Agreement between findings of the virtual visit and the corresponding in-person clinical visit was assessed using kappa values. RESULTS Twenty-two patients were contacted regarding study enrolment and 17 patients were enrolled (ages 23-63, mean 48.2, 6M, 11F). Of 16 patients who participated, all completed dressing removal. Ten of 16 patients removed their sutures successfully. Fourteen patients captured a clinically adequate wound photo and 15 patients answered a question about median nerve symptoms. Fourteen patients captured a range of motion video. Software assessments of surgical wounds, nerve symptoms and physical exams agreed strongly with clinical assessments. DISCUSSION Most patients were able to respond to a question about their symptoms, provide clinical assessment of their wound via a photo and record a video of their range of motion. Suture removal was the most difficult task. More investigation is needed to determine which patients can reliably remove their sutures.
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Tofte JN, Anthony CA, Polgreen PM, Buckwalter JA, Caldwell LS, Fowler TP, Ebinger T, Hanley JM, Dowdle SB, Holte AJ, Arpey NC, Lawler EA. Postoperative care via smartphone following carpal tunnel release. J Telemed Telecare 2018; 26:223-231. [PMID: 30428766 DOI: 10.1177/1357633x18807606] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction This study explores a novel smartphone application for postoperative care following carpal tunnel release (CTR). We hypothesized that a software-based ‘virtual visit’ for CTR could be safe, effective and convenient for the patient. Methods Our group developed the software application utilized in this study. Interactive steps with video instructions enabled patients to complete dressing and suture removal, capture a wound photo, answer a question about median nerve symptoms and capture a video of finger range of motion. Adult patients undergoing endoscopic or open CTR were enrolled. Prior to their scheduled postoperative visit, patients received and completed the module using their smartphone. Agreement between findings of the virtual visit and the corresponding in-person clinical visit was assessed using kappa values. Results Twenty-two patients were contacted regarding study enrolment and 17 patients were enrolled (ages 23–63, mean 48.2, 6M, 11F). Of 16 patients who participated, all completed dressing removal. Ten of 16 patients removed their sutures successfully. Fourteen patients captured a clinically adequate wound photo and 15 patients answered a question about median nerve symptoms. Fourteen patients captured a range of motion video. Software assessments of surgical wounds, nerve symptoms and physical exams agreed strongly with clinical assessments. Discussion Most patients were able to respond to a question about their symptoms, provide clinical assessment of their wound via a photo and record a video of their range of motion. Suture removal was the most difficult task. More investigation is needed to determine which patients can reliably remove their sutures.
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Seol D, Tochigi Y, Bogner AM, Song I, Fredericks DC, Kurriger GL, Smith SM, Goetz JE, Buckwalter JA, Martin JA. Effects of knockout of the receptor for advanced glycation end-products on bone mineral density and synovitis in mice with intra-articular fractures. J Orthop Res 2018; 36:2439-2449. [PMID: 29667227 PMCID: PMC6128287 DOI: 10.1002/jor.24021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 04/12/2018] [Indexed: 02/04/2023]
Abstract
Our group employed the mouse closed intra-articular fracture (IAF) model to test the hypothesis that the innate immune system plays a role in initiating synovitis and post-traumatic osteoarthritis (PTOA) in fractured joints. A transgenic strategy featuring knockout of the receptor for advanced glycation end-products (RAGE -/- ) was pursued. The 42 and 84 mJ impacts used to create fractures were in the range previously reported to cause PTOA at 60 days post-fracture. MicroCT (μCT) was used to assess fracture patterns and epiphyseal and metaphyseal bone loss at 30 and 60 days post-fracture. Cartilage degeneration, synovitis, and matrix metalloproteinase (MMP-3, -13) expression were evaluated by histologic analyses. In wild-type mice, μCT imaging showed that 84 mJ impacts led to significant bone loss at 30 days (p < 0.05), but recovered to normal at 60 days. Bone losses did not occur in RAGE-/- mice. Synovitis was significantly elevated in 84 mJ impact wild-type mice at both endpoints (30 day, p = 0.001; 60 day, p = 0.05), whereas in RAGE-/- mice synovitis was elevated only at 30 days (p = 0.02). Mankin scores were slightly elevated in both mouse strains at 30 days, but not at 60 days. Immunohistochemistry revealed significant fracture-related increases in MMP-3 and -13 expression at 30 days (p < 0.05), with no significant difference between genotypes. These findings indicated that while RAGE -/- accelerated recovery from fracture and diminished synovitis, arthritic changes were temporary and too modest to detect an effect on the pathogenesis of PTOA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2439-2449, 2018.
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Day MA, Compton JT, Buckwalter JA. Leland G. Hawkins, MD-His Life and Orthopaedic Legacy: Talus Fractures and the Hawkins Classification. THE IOWA ORTHOPAEDIC JOURNAL 2018; 38:1-8. [PMID: 30104918 PMCID: PMC6047388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The long history of excellence and continued success of the University of Iowa Department of Orthopedics and Rehabilitation is due to the dedication and talent of generations of faculty, residents and staff. Many former Iowa Orthopedic residents have made significant contributions and become leaders in Orthopedic surgery. An orthopedic surgeon and scholar with roots at the University of Iowa deserving of tribute is Dr. Leland Greene Hawkins. His seminal investigation and interest in fractures of the talus established the well-known Hawkins Classification for talar neck fractures, which revolutionized treatment and quantified the risk of progression to avascular necrosis, earning him attention and respect worldwide.
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Bechtold JE, Williams BR, Weinstein SL, Polly DW, Pugely AJ, Buckwalter JA, Albanese SA, Bozic KJ, Snyder BD. The Pursuit of Scholarship: Why We Should Care About Resident Research. J Bone Joint Surg Am 2017; 99:e119. [PMID: 29135674 DOI: 10.2106/jbjs.16.01502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Research is a foundational component of an orthopaedic residency. It fosters intellectual curiosity and pursuit of excellence, while teaching discipline and the scientific method. These are the key principles for careers in both community-based practice and academia. Currently, no consensus exists on how to best engage residents and support their research endeavors. In 2014, the American Academy of Orthopaedic Surgeons Board of Specialty Societies Research and Quality Committee convened a Clinician-Scientist Collaboration Workgroup. The workgroup's task was to identify barriers to clinical and basic science research, and to propose feasible recommendations to overcome these barriers. Herein, we have compiled the opinions of various stakeholder constituencies on how to foster scholarly pursuits during an orthopaedic residency. These opinions reflect the workgroup's conclusions that research is directly and indirectly influenced by funding, departmental support, and mentorship, and that early exposure and dedicated time to pursue scholarly activities may have a positive impact on lifelong research interests.
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Martin JA, Anderson DD, Goetz JE, Fredericks D, Pedersen DR, Ayati BP, Marsh JL, Buckwalter JA. Complementary models reveal cellular responses to contact stresses that contribute to post-traumatic osteoarthritis. J Orthop Res 2017; 35:515-523. [PMID: 27509320 PMCID: PMC5303196 DOI: 10.1002/jor.23389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/05/2016] [Indexed: 02/04/2023]
Abstract
Two categories of joint overloading cause post-traumatic osteoarthritis (PTOA): single acute traumatic loads/impactions and repetitive overloading due to incongruity/instability. We developed and refined three classes of complementary models to define relationships between joint overloading and progressive cartilage loss across the spectrum of acute injuries and chronic joint abnormalities: explant and whole joint models that allow probing of cellular responses to mechanical injury and contact stresses, animal models that enable study of PTOA pathways in living joints and pre-clinical testing of treatments, and patient-specific computational models that define the overloading that causes OA in humans. We coordinated methodologies across models so that results from each informed the others, maximizing the benefit of this complementary approach. We are incorporating results from these investigations into biomathematical models to provide predictions of PTOA risk and guide treatment. Each approach has limitations, but each provides opportunities to elucidate PTOA pathogenesis. Taken together, they help define levels of joint overloading that cause cartilage destruction, show that both forms of overloading can act through the same biologic pathways, and create a framework for initiating clinical interventions that decrease PTOA risk. Considered collectively, studies extending from explants to humans show that thresholds of joint overloading that cause cartilage loss can be defined, that to at least some extent both forms of joint overloading act through the same biologic pathways, and interventions that interrupt these pathways prevent cartilage damage. These observations suggest that treatments that decrease the risk of all forms of OA progression can be discovered. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:515-523, 2017.
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Murtha AS, Johnson AE, Buckwalter JA, Rivera JC. Total knee arthroplasty for posttraumatic osteoarthritis in military personnel under age 50. J Orthop Res 2017; 35:677-681. [PMID: 27177309 DOI: 10.1002/jor.23290] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/10/2016] [Indexed: 02/04/2023]
Abstract
United States military personnel frequently suffer knee injuries. The resulting progressive posttraumatic osteoarthritis (PTOA) causes significant disability in these young high-demand patients for which total knee arthroplasty (TKA) is the only effective treatment of their pain and impairment. Yet the use of this option for treatment of PTOA has not been studied. This retrospective review identified 74 knees in 64 U.S. military personnel who underwent TKA at ≤50 years of age during an 8-year period at a tertiary-care, academic, military medical center. Fifty-five knees (74.3%) experienced one or more prior ligamentous, meniscal, or chondral injuries prior to arthroplasty. Only one subject had a history of osteochondral intra-articular fracture. The average at injury was 29.2 years (95%CI of ±2.50) with an average age at arthroplasty of 44.3 years (±1.11). The most common injury was anterior cruciate ligament rupture (n = 19) with a mean time to TKA of 23.1 (±10.54) and 18.8 years (±7.01) when concomitant meniscal pathology was noted. Nineteen patients were noted to have radiographic and symptomatic end-stage osteoarthritis without a specified etiology at 41.4 years (±1.47) and underwent subsequent TKA. This is the first study to evaluate treatment of end-stage PT OA in young people treated with TKA, finding that the incidence of PTOA as an indication for arthroplasty is significantly higher than among civilians. In this otherwise healthy, high-demand patient population, the rate of OA progression following knee injury is accelerated and the long term implications can be career and life altering. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:677-681, 2017.
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Buckwalter JA, Elkins JM. The Scarcity of Orthopaedic Physician Scientists. THE IOWA ORTHOPAEDIC JOURNAL 2017; 37:219-224. [PMID: 28852361 PMCID: PMC5508265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Breakthrough advances in medicine almost uniformly result from the translation of new basic scientific knowledge into clinical practice, rather than from assessment, modification or refinement of current methods of diagnosis and treatment. However, as is intuitively understood, those most responsible for scientific conception and creation-scientists - are generally not the ones applying these advances at the patient's bedside or the operating room, and vice versa. Recognition of the scarcity of clinicians with a background that prepares them to develop new basic knowledge, and to critically evaluate the underlying scientific basis of methods of diagnosis and treatment, has led to initiatives including federally funded Physician-Scientist programs, whereby young, motivated scholars begin a rigorous training, which encompasses education and mentorship within both medical and scientific fields, culminating in the conferment of both MD and PhD degrees. Graduates have demonstrated success in integrating science into their academic medical careers. However, for unknown reasons, orthopaedic surgery, more than other specialties, has struggled to recruit and retain physician-scientists, who possess a skill set evermore rare in today's increasingly complicated medical and scientific landscape. While the reasons for this shortfall have yet to be completely elucidated, one thing is clear: If orthopaedics is to make significant advances in the diagnosis and treatment of musculoskeletal diseases and injuries, recruitment of the very best and brightest physician-scientists to orthopaedics must become a priority. This commentary explores potential explanations for current low-recruitment success regarding future orthopaedic surgeon-scientists, and discusses avenues for resolution.
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Zhou C, Zheng H, Buckwalter JA, Martin JA. Enhanced phagocytic capacity endows chondrogenic progenitor cells with a novel scavenger function within injured cartilage. Osteoarthritis Cartilage 2016; 24:1648-55. [PMID: 27130155 PMCID: PMC4992612 DOI: 10.1016/j.joca.2016.04.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 04/01/2016] [Accepted: 04/19/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Articular cartilage harbors chondrogenic progenitor cells (CPCs), a population that responds chemotactically to cell death. Because this behavior is reminiscent of macrophages, we hypothesized that CPCs have macrophage-like capabilities for scavenging cell and tissue debris through phagocytosis. DESIGN CPCs, chondrocytes, synoviocytes, and macrophages were cultured with fluorophore-labeled chondrocyte debris for 3, 6, 12, or 24 h. Debris internalization was quantified by confocal microscopy and flow cytometry. Confocal microscopy was also used to test CPCs and chondrocytes for uptake of fluorophore-labeled fibronectin fragments (Fn-fs), a form of extracellular matrix debris. Lysosome activity and mass in CPCs and chondrocytes were measured using fluorescent probes. The relative expression of phagocytosis-related genes and proteins was evaluated by polymerase chain reaction (PCR) and immunoblotting, respectively. Pulse-chase experiments were performed to determine if the debris internalized by CPCs and chondrocytes was cleared, and if clearance was affected by a cathepsin B inhibitor. RESULTS More macrophages, synoviocytes, and CPCs internalized cell debris than chondrocytes at all time points. While uptake remained flat in chondrocytes at ∼10%, in the other cell types it peaked at more than 60% after 12-24 h. Relative to chondrocytes, CPCs showed significantly higher rates of Fn-fs engulfment, greater lysosome activity and mass, and over-expressed phagocytosis-related genes and proteins. Pulse-chase experiments revealed time- and cathepsin B-dependent clearance of cell debris in CPCs, but not in chondrocytes. CONCLUSIONS CPCs phagocytized cell and matrix debris much more efficiently than chondrocytes, supporting the hypothesis that they play a macrophage-like role in injured cartilage.
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