Gunshot Trauma Patients Have Higher Risk of PTSD Compared With Blunt Trauma and Elective Populations: A Retrospective Comparative Study of Outpatient Orthopaedic Care.

BACKGROUND: Posttraumatic stress disorder (PTSD) has been extensively studied in patients who have experienced natural disasters or military conflict, but there remains a substantial gap in knowledge about the prevalence of PTSD after civilian orthopaedic trauma, especially as related to firearms. Gun violence is endemic in the United States, especially in urban centers, and the mental impact is often minimized during the treatment of physical injuries. QUESTIONS/PURPOSES: (1) Do patients who experience gunshot wound (GSW) trauma have higher PTSD screening scores compared with patients with blunt or other trauma (for example, motor vehicle and motorcycle accidents or stab wounds) and those with elective conditions (for example, arthritis, tendinitis, or nerve compression)? (2) Are PTSD scores correlated with pain scores in patients with GSW trauma, those with non-GSW trauma, and patients with elective orthopaedic symptoms? METHODS: We performed a retrospective study of adults older than 18 years of age presenting to an orthopaedic clinic over an 8-month period between August 2021 and May 2022. All patients presenting to the clinic were approached for inclusion (2034 patients), and 630 new or postoperative patients answered study surveys as part of routine care. Patients were divided into three cohorts based on the orthopaedic condition with which they presented, whether gunshot trauma, blunt trauma, or elective orthopaedic symptoms. Overall, the results from 415 patients were analyzed, including 212 patients with elective orthopaedic symptoms, 157 patients with non-GSW trauma, and 46 patients with GSW trauma. Clinical data including demographic information were collected at the time of appointment and abstracted along with results from the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, short screening questionnaire, which uses a 7-item scale scored from 0 to 7 (with higher scores representing worse symptoms), and from the numeric rating scale for pain (range 0 to 10). Both questionnaires were routinely administered by medical assistants at patient intake. The proportions of patients completing PTSD scoring were 45% (95) in the elective group, 74% (116) in the group with non-GSW trauma, and 85% (39) in the group with GSW trauma (p = 0.01). We compared the PTSD scores across the three groups and then dichotomized the scores as a negative versus positive screening result at a value of ≥ 4 with further comparative analysis. The correlation between pain and PTSD scores was also evaluated. RESULTS: Patients with GSW trauma had higher mean ± SD PTSD scores compared with those who had non-GSW trauma (4.87 ± 4.05 versus 1.75 ± 2.72, mean difference 3.21 [95% CI 1.99 to 4.26]; p < 0.001) and those who presented with elective conditions (4.87 ± 4.05 versus 0.49 ± 1.04, mean difference 4.38 [95% CI 3.50 to 5.26]; p < 0.001). When dichotomized for positive or negative PTSD screening results, patients with GSW trauma had a higher risk of having PTSD (64% [25 of 39]) compared with patients with non-GSW trauma (27% [31 of 116], relative risk 2.40 [95% CI 1.64 to 3.51]; p < 0.001) and compared with patients with elective conditions (4% [4 of 95], relative risk 15.22 [95% CI 5.67 to 40.87]; p < 0.001). Pain scores were correlated with PTSD scores only for patients with non-GSW trauma (ρ = 0.37; p < 0.0001). No correlation with pain scores was present for patients with GSW (ρ = 0.24; p = 0.16) or patients with elective conditions (ρ = -0.04; p = 0.75). CONCLUSION: In an orthopaedic clinic population, the prevalence of positive screening for PTSD was highest in the population sustaining gunshot trauma as compared with blunt or other trauma and elective orthopaedic conditions. Interestingly, pain scores correlated with PTSD screening only in the patients with non-GSW trauma. These differences suggest a substantial difference in the populations at risk of PTSD after trauma. Overall, the psychological impacts of gun trauma are poorly understood. The next step would be to prospectively study the differences and timelines of PTSD screening in patients with GSW trauma in comparison with patients with blunt or other trauma to better define the treatment needs in this population. LEVEL OF EVIDENCE: Level III, prognostic study.

Do preoperative glucose levels predict risk of complications in orthopaedic surgery?

PURPOSE: Post-operative hyperglycemia is a known risk factor for post-surgical complications. The predictive value of pre-operative blood glucose levels, however, is less understood. This study aimed to determine if pre-operative screening blood glucose levels affect the rate of post-operative infection or wound complications. We also investigated if case urgency or anatomic location alters this relationship. METHODS: A single-institution retrospective chart review was performed to evaluate patients treated between 2018 and 2021. Subjects ≥ 18 years with closed, non-infected orthopaedic diagnoses requiring surgery were included. Case urgency, demographics, comorbidities, blood glucose level within twelve h prior to surgery, and hemoglobin A1c level within 3 months of surgery, were collected. Infections and wound complications were recorded as outcomes. RESULTS: A total of 775 subjects with a mean age of 61 (range 18-96) were identified, including 543 elective and 232 trauma patients, with a mean pre-operative fasting glucose value of 127.7 mg/dL (range, 49-388 mg/dL) and average HbA1c of 6.9%. The odds of infectious complications were increased by a factor of 1.01 for every 1-point increase in blood glucose (95% CI 1.01-1.02; p < 0.01). CONCLUSIONS: Pre-operative blood glucose levels greater than 137 mg/dL were associated with an increase in wound complications, but not deep infections. Infection rates stratified by anatomic site and case urgency were not impacted by pre-operative glucose levels. The increased risk of poor wound healing in patients with pre-operative hyperglycemia demonstrates that day of surgery point-of-care blood glucose screening can be a useful risk stratification tool.

Radial Nerve Palsy in the Setting of Humeral Shaft Fracture.

The upper limb has a complex anatomy comprised of many nerve and vascular structures, making humeral shaft fractures extremely important. Injury to the humeral shaft commonly occurs due to trauma and affects younger male or older female patients. The radial nerve travels along the spiral groove of the humerus, placing it at an increased risk of damage in humeral shaft fractures. If injured, there are a variety of classifications of radial nerve injury, different indications for exploration, and treatment methods that orthopedic surgeons have available in treating these injuries. This review aims to discuss the etiology of humeral shaft fracture-associated radial nerve palsy, tools for diagnosis, and treatment.

Depression, anxiety, and post-traumatic stress disorder following upper versus lower extremity fractures.

INTRODUCTION: Orthopaedic trauma has been linked to major depressive disorder (MDD), generalized anxiety disorder (GAD), and post-traumatic stress disorder (PTSD). Post-injury rates of psychiatric diagnoses and their relationship to various injury characteristics are not well characterized. We aimed to determine the association between orthopaedic trauma and MDD, GAD, and PTSD diagnoses at 5-year follow-up. METHODS: A national insurance claims database was used to create upper extremity fracture (UEF) and lower extremity fracture (LEF) cohorts, with further stratification by isolated versus multiple fractures. Patient undergoing elective upper or lower extremity orthopaedic procedures served as controls. Rates of post-injury psychiatric diagnoses were calculated. Univariate logistic regression was conducted after matching in a 1:1 ratio based on relevant comorbidities such as psychiatric history. All significant variables were included in multivariate analysis. RESULTS: A total of 308,578 UEF patients and 360,510 LEF patients were identified. Within the UEF cohort, the diagnosis rates following either isolated or multiple fractures were identified: MDD (25% to 30%), GAD (10% to 11%), and PTSD (4%). LEF cohort rates were as follows: MDD (30% to 38%), GAD (11% to 14%), and PTSD (4% to 7%). Compared to non-injured controls, both the UEF and LEF cohorts were associated with higher rates of all psychiatric diagnoses. In comparing UEF and LEF cohorts, isolated UEF was associated with MDD, GAD, and PTSD; however, multiple UEF was associated with MDD and GAD, whereas multiple LEF was associated with PTSD. CONCLUSION: Psychiatric pathology is prevalent following orthopaedic trauma. Even after controlling for psychiatric history, orthopaedic trauma is independently associated with post-injury psychiatric diagnoses and may be more predictive of PTSD and GAD than of MDD. Upper extremity fractures may portend higher psychiatric risk. With negative stigma surrounding mental health and the early role of orthopaedic surgeons in providing care, it is imperative to normalize psychiatric care with patients and discuss warning symptoms that may indicate the onset of psychiatric disorders. LEVEL OF EVIDENCE: Prognostic, Level III.

The Epidemiology of Radial Tunnel Syndrome and Its Overlap With Lateral Epicondylitis.

PURPOSE: Radial tunnel syndrome (RTS) is characterized by nerve compression affecting the posterior interosseous nerve branch in the forearm, and its symptoms often overlap with those of lateral epicondylitis (LE). The purpose of this study was to examine the epidemiology of RTS, frequency of injections and surgical release, and overlap of RTS with LE. METHODS: We queried the PearlDiver database to identify RTS in patients older than 18 years. Demographic data, diagnostic or therapeutic injection within 30 days of diagnosis, surgical release within 1 year of diagnosis, and 90-day postoperative complication rates were evaluated. Using International Classification of Diseases, 10th Revision, laterality codes, we also determined the number of patients who had same-side RTS and LE and the proportion of patients who subsequently underwent simultaneous RT release and LE debridement. RESULTS: The prevalence of RTS in a representative United States insurance database was 0.091%, and the annual incidence was 0.0091%. There were 75,459 patients identified with an active RTS diagnosis. The mean age at the time of diagnosis was 52 years (range, 18-81 years), 55% were women, and 1,833 patients (2.4%) underwent RT release within 1 year. Fewer than 3% of the patients received an injection within 30 days of RTS diagnosis. The 90-day postoperative complication rates were low: 5% of the patients required hospital readmission and 2.1% underwent revision surgery. Approximately 5.7% of the patients with RTS also had a diagnosis of LE on the same side within 6 months of RTS diagnosis. In patients with ipsilateral RTS and LE who underwent surgery, 59.1% underwent simultaneous RT release and LE debridement, whereas 40.9% underwent isolated radial tunnel release. CONCLUSIONS: The analysis of a large insurance database showed that the diagnosis of RTS is rarely assigned, suggesting that the incidence of this nerve compression is low. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic III.

Radial Tunnel Syndrome: Review and Best Evidence.

Radial tunnel syndrome (RTS) is caused by compression of the posterior interosseous nerve and consists of a constellation of symptoms that have previously been characterized as aspects of other disease processes, as opposed to a distinct diagnosis. First described in the mid-20th century as "radial pronator syndrome," knowledge regarding the anatomy and presentation of RTS has advanced markedly over the past several decades. However, there remains notable controversy and ongoing research regarding diagnostic imaging, nonsurgical treatment options, and indications for surgical intervention. In this review, we will discuss the anatomic considerations of RTS, relevant physical examination findings, potential diagnostic modalities, and outcomes of several treatment options.

A global perspective on gun violence injuries.

INTRODUCTION AND DEFINITIONS: Civilian gunshot violence is a growing public health issue on a global scale. Treatment of patients with gunshot injuries is based on algorithms derived from military studies, but the distinct differences in weaponry, energy of injury, timing and type of care, and environment translate to a gap in knowledge. With a focus on non-accidental gunshot trauma and excluding suicide etiologies, we propose to build a collaborative research group to address important questions focused on best practices for gunshot injury patients. PRE-HOSPITAL CARE: There are important differences in the care of gunshot victims across the globe; some countries provide advanced interventions in the field and others deliver basic support until transport to a higher level of care in hospital. Some simple interventions include the use of extremity tourniquets and intravenous fluid support; others to consider are tranexamic acid, whole blood, and hemostatic agents. ACUTE TREATMENT: Control of exsanguinating hemorrhage is a key priority for gunshot injuries. Military doctrine has evolved to prioritize exsanguination over airway or breathing as the critical first step. The X-ABC protocol focuses on exsanguinating hemorrhage, then standard evaluation of Airway, Breathing and Circulation (ABCs) to enhance survival in trauma patients. The timing of bony stabilization, in terms of damage-control vs definitive care, needs further study in this population, as does use of antibiotics for bony extremity injuries. Finally, recognition of the mental health effects of gun trauma, including post-traumatic stress disorder (PTSD), anxiety disorders, substance abuse and depression is important in advocating for prevention such as implementation of social support and specific interventions. DEFINITIVE CARE: The need for abdominal closure after exploratory laparotomy, definitive fracture treatment, and other treatment all contribute to length of stay for gunshot injured patients. Optimizing stabilization allows earlier mobilization and decreases nosocomial complications. Nerve injuries are often a source of long-term disability and their evaluation and treatment require further investigation. RESOURCES AND ETHICS: There are growing numbers of mass-casualty gunshot events, which require consideration of how to organize and use resources for treatment, including staff, operating room access, blood products, and order of treatment. Drills and planning for incident command hierarchy and communication are key to optimizing resource utilization. The ethics of choosing treatment priorities and resources are important considerations as well.

Corrigendum to "Characterization of the essential role of bone morphogenetic protein 9 (BMP9) in osteogenic differentiation of mesenchymal stem cells (MSCs) through RNA interference" [Genes & Diseases 5(2018):172-184].

[This corrects the article DOI: 10.1016/j.gendis.2018.04.006.].

Corrigendum to "Sox9 augments BMP2-induced chondrogenic differentiation by downregulating Smad7 in mesenchymal stem cells (MSCs)" [Genes & Diseases 4 (2017) 229-239].

[This corrects the article DOI: 10.1016/j.gendis.2017.10.004.].

Pediatric Ganglions of the Hand and Wrist: A Review of Current Literature.

The etiology, epidemiology, and treatment outcomes of ganglions in children have not been studied in depth. Most research has mainly focused on adults with this condition, with some research suggesting differing epidemiology and outcomes in the pediatric population. This review focuses on the existing literature on pediatric ganglions of the hand and wrist, highlighting 17 studies focused on prevalence and treatment outcomes. Within the pediatric population, epidemiology and outcomes differ depending on patient age. In children aged <10 years, cysts present on the volar aspect of the wrist and are generally amenable to observation, with spontaneous regression. For patients aged >10 years, ganglions resemble those in the adult population and present on the dorsal aspect of the wrist. Open surgical excision demonstrates a relatively low recurrence rate with minimal complications and is currently recommended for treatment.

Gunshot-Related Upper Extremity Nerve Injuries at a Level 1 Trauma Center.

PURPOSE: Gunshot wounds can result in a spectrum of injuries to nerves, with little data to guide definitive treatment. We performed a retrospective evaluation of gunshot-related upper extremity injuries in an urban trauma center to analyze epidemiology, associated injuries, and short-term outcomes. We hypothesized that gunshot-related injuries would involve soft tissue cavitation, inducing axonotmesis and neuropraxia rather than neurotmesis injuries. METHODS: All patients over the age of 16 with upper extremity gunshot trauma from May 2018 to May 2019 were identified through the University of Chicago orthopaedic and general surgery trauma databases. Initial nerve injuries were identified by physical examination. Patient demographic data, soft tissue and skeletal injury, treatment modality, and return of function were collected. RESULTS: Ballistic injuries in 1302 patients were treated over 12 months. We identified 126 upper extremity gunshot injuries in 117 patients. Thirty-eight upper extremities (38 patients) had a documented nerve deficit (38/126, 30%) with a follow-up rate of 94% (34/36) at a mean of 351 days after injury (median, 202 days; range, 13-929 days). One patient had a subacute transradial amputation, and 1 patient was deceased at final follow-up. The presence of vascular injury and fracture increased the rate of neurologic injury after gunshot injuries. At the most recent follow-up, 68% (23/34) of patients with upper extremity injury had improvement in nerve function as measured by objective clinical assessment, with 24% (8/34) experiencing full recovery at an average of 368 days (median, 261 days; range, 41-929 days). CONCLUSIONS: Nerve injury after ballistic trauma to the upper extremity is common. Vascular injury and fractures were associated with a higher risk of nerve injury. Short-term improvement in nerve function was seen in over half the cohort, suggesting a predominance of neuropraxic effects. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

Temporal Relationship of Corticosteroid Injection and Open Release for Trigger Finger and Correlation With Postoperative Deep Infections.

PURPOSE: Previous single-institution studies have shown a relationship between corticosteroid injection and infection after surgery if open trigger release occurs within 90 days. We queried an insurance claims database to evaluate the temporal relationship between a corticosteroid injection and the development of a surgical site infection requiring secondary surgery in patients undergoing trigger release. METHODS: The PearlDiver database was queried for adults who underwent unilateral trigger finger release surgery from 2012 to 2018. The total number of injections, time from last injection to surgery, and preoperative antibiotic use were determined, in addition to the rates of postoperative administration of antibiotics and deep infection requiring surgery at 30, 60, and 90 days after surgery. Logistic regression analysis was used to evaluate the odds of deep infection at 30, 60, and 90 days. RESULTS: A total of 14,686 patients were included; at least 1 corticosteroid injection was administered to 5,173 patients prior to surgery. When grouped based on whether a corticosteroid injection was administered prior to surgery, the postoperative infection rates between the groups were similar at 30, 60, and 90 days. When surgery was performed within 1 month of injection, increased odds of deep infection requiring irrigation and debridement were seen at 60 (odds ratio 2.92 [1.01-7.52]) and 90 days (odds ratio 3.01 [1.13-7.25]). Postoperative antibiotic use in the groups with and without a preoperative injection was similar at all queried time points, but patients who underwent open trigger finger release within 1 month of a prior injection had significantly increased odds (odds ratio 5.77 [1.41-22.06]) of using antibiotics after surgery. Male sex, a higher Elixhauser comorbidity index, and rheumatoid arthritis were additional independent risk factors for a deep infection. CONCLUSIONS: Patients who undergo open trigger release within 1 month of a corticosteroid injection are at increased odds of developing a postoperative infection requiring surgical debridement. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

De Quervain Tenosynovitis: An Evaluation of the Epidemiology and Utility of Multiple Injections Using a National Database.

PURPOSE: We hypothesized that repeat injections are associated with a decreased rate of success and that the success rate of injections correlates with patient comorbidities. METHODS: Using a commercially available insurance database, patients diagnosed with De Quervain tenosynovitis were identified using International Classification of Diseases, Ninth Revision and Tenth Revision codes and stratified by therapeutic interventions, including therapy, injections, and surgery, as well as comorbidities. Injection failure was defined as a patient receiving a repeat injection or subsequent surgical management. Success was defined as no further therapies identified after an intervention. RESULTS: From 2007 to 2017, 33,420 patients with a primary diagnosis of De Quervain tenosynovitis were identified. Women represented 77.5% (25,908) of the total and were 2.6 times more likely to be diagnosed than men. Black patients were more likely to be diagnosed than White patients. Black and White women were found to have the highest incidence (relative risk 3.4 and 2.3, respectively, compared with White men). Age was also significantly correlated with an increased risk of diagnosis of the condition, with a peak incidence at the age of 40-59 years (relative risk, 10.6). Diabetes, rheumatoid arthritis, lupus, and hypothyroidism were associated with an increased risk of diagnosis. Overall, 53.3% of the patients were treated with injections, 11.6% underwent surgery, and 5.2% underwent therapy. Treatment with a single injection was successful in 71.9% of the patients, with 19.7% receiving a repeat injection and 8.4% treated with surgery. The overall success rate of subsequent injections was 66.3% for the second injection and 60.5% for the third. The initial injection had a higher rate of success in diabetics than in nondiabetics; however, the difference (2%) was not clinically relevant. CONCLUSIONS: Although the success rate for the treatment of De Quervains tenosynovitis decreases with multiple injections, repeat injections have a high rate of success and are a viable clinical option. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

A functional autophagy pathway is essential for BMP9-induced osteogenic differentiation of mesenchymal stem cells (MSCs).

Mesenchymal stem cells (MSCs) are capable of differentiating into bone, cartilage and adipose tissues. We identified BMP9 as the most potent osteoinductive BMP although detailed mechanism underlying BMP9-regulated osteogenesis of MSCs is indeterminate. Emerging evidence indicates that autophagy plays a critical role in regulating bone homeostasis. We investigated the possible role of autophagy in osteogenic differentiation induced by BMP9. We showed that BMP9 upregulated the expression of multiple autophagy-related genes in MSCs. Autophagy inhibitor chloroquine (CQ) inhibited the osteogenic activity induced by BMP9 in MSCs. While overexpression of ATG5 or ATG7 did not enhance osteogenic activity induced by BMP9, silencing Atg5 expression in MSCs effectively diminished BMP9 osteogenic signaling activity and blocked the expression of the osteogenic regulator Runx2 and the late marker osteopontin induced by BMP9. Stem cell implantation study revealed that silencing Atg5 in MSCs profoundly inhibited ectopic bone regeneration and bone matrix mineralization induced by BMP9. Collectively, our results strongly suggest a functional autophagy pathway may play an essential role in regulating osteogenic differentiation induced by BMP9 in MSCs. Thus, restoration of dysregulated autophagic activity in MSCs may be exploited to treat fracture healing, bone defects or osteoporosis.

What Are the Patient-reported Outcomes of Trapeziectomy and Tendon Suspension at Long-term Follow-up?

BACKGROUND: There are multiple options for the treatment of thumb carpometacarpal joint osteoarthritis (CMC1 OA), with evidence for pain relief and improved function. Although simple trapeziectomy has the lowest complication risk, tendon suspension of the first metacarpal and interposition is still the most commonly used surgical procedure in patients with CMC1 OA. Although there are several reports of good short-term results after trapeziectomy and tendon suspension-interposition arthroplasty, few studies have evaluated long-term outcomes. This study is one of the largest and longest follow-up evaluations of a cohort of patients with CMC1 OA who were treated with trapeziectomy and suspension-interposition arthroplasty, capturing 96% of the original cohort for evaluation. QUESTIONS/PURPOSES: (1) After trapeziectomy and tendon suspension surgery, what are the long-term, patient-reported outcomes and clinical measurements (strength and ROM); and in unilateral procedures, how do these parameters compare with those of the contralateral hand that was not operated on? (2) What is the mean subsidence (unloaded trapezial space), and does pinch strength correlate with the amount of subsidence? METHODS: From 1998 to 2005, 130 patients underwent trapeziectomy and abductor pollicis longus (APL) suspension-interposition arthroplasty for CMC1 OA at one orthopaedic department. During this period, 15 patients were treated with CMC1 arthrodesis and four were treated with implant arthroplasty, for a total of 149 patients. The surgeons used APL suspensionplasty for most patients, based on age and expected postoperative function; they also employed this procedure to avoid hardware or implant failure issues. The 100 living patients were asked to participate in this retrospective study, 96% (96) of whom were enrolled. The mean age at surgery was 58 ± 7 years. The patients completed a two-item thumb pain scale (modified from the SF-36 body pain scale), a hand pain VAS (average level of pain experienced over the week preceding measurement), and the 11-item QuickDASH. Patient-reported outcomes data were obtained from all 96 patients, and 83% (80) of patients underwent bilateral hand radiography and a physical examination at a mean follow-up of 17 ± 2.4 years. We calculated outcome data for each patient, and in 39 patients with unilateral surgery and intact contralateral CMC1 joint, we compared the operated side with the contralateral side. We compared our outcome data with that from the Swedish National Quality Registry for Hand Surgery (HAKIR), noting comparable outcomes for pain and QuickDASH scores. RESULTS: At long-term follow-up after trapeziectomy and APL suspension surgery, the mean thumb pain score was 19 ± 26, hand pain VAS score 23 ± 25, and QuickDASH score 26 ± 21. In the patients with unilateral surgery and intact contralateral CMC1 joint, the thumb pain score for the operated side was lower than the contralateral side, specifically 19 ± 25 compared with 29 ± 30 (mean difference -9.8 [95% CI -19.5 to -0.2]; p = 0.045); hand pain VAS score was 24 ± 23 versus 30 ± 25 (mean difference -6.1 [95% CI -15.2 to 3.1]; p = 0.19), and the QuickDASH score was 27 ± 19. Grip strength showed no differences between the operated and contralateral sides (mean 16.7 ± 7.3 kg versus 16.6 ± 6.9 kg, mean difference 0.1 [95% CI -1.6 to 1.8]; p = 0.90), while pinch was different (4.4 ± 1.4 versus 5.0 ± 1.5 kg, mean difference -0.6 [95% CI -0.9 to -0.3]; p = 0.001). The mean trapezial space was 4.4 ± 2.2 mm, and there was no association between the trapezial space and pinch strength (0.07 kg [95% CI -0.04 to 0.18] per mm of space; p = 0.17). CONCLUSION: The finding of comparable pain and function between operated and unoperated sides at long-term follow-up suggests that trapeziectomy and tendon suspension-interposition arthroplasty provides predictable outcomes, and surgeons can use these data to counsel patients that surgery can potentially return them to comparable use. However, as patients often have asymptomatic radiographic OA on the contralateral side, future studies are needed to examine the impact of asymptomatic disease on function. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Applications of Biocompatible Scaffold Materials in Stem Cell-Based Cartilage Tissue Engineering.

Cartilage, especially articular cartilage, is a unique connective tissue consisting of chondrocytes and cartilage matrix that covers the surface of joints. It plays a critical role in maintaining joint durability and mobility by providing nearly frictionless articulation for mechanical load transmission between joints. Damage to the articular cartilage frequently results from sport-related injuries, systemic diseases, degeneration, trauma, or tumors. Failure to treat impaired cartilage may lead to osteoarthritis, affecting more than 25% of the adult population globally. Articular cartilage has a very low intrinsic self-repair capacity due to the limited proliferative ability of adult chondrocytes, lack of vascularization and innervation, slow matrix turnover, and low supply of progenitor cells. Furthermore, articular chondrocytes are encapsulated in low-nutrient, low-oxygen environment. While cartilage restoration techniques such as osteochondral transplantation, autologous chondrocyte implantation (ACI), and microfracture have been used to repair certain cartilage defects, the clinical outcomes are often mixed and undesirable. Cartilage tissue engineering (CTE) may hold promise to facilitate cartilage repair. Ideally, the prerequisites for successful CTE should include the use of effective chondrogenic factors, an ample supply of chondrogenic progenitors, and the employment of cell-friendly, biocompatible scaffold materials. Significant progress has been made on the above three fronts in past decade, which has been further facilitated by the advent of 3D bio-printing. In this review, we briefly discuss potential sources of chondrogenic progenitors. We then primarily focus on currently available chondrocyte-friendly scaffold materials, along with 3D bioprinting techniques, for their potential roles in effective CTE. It is hoped that this review will serve as a primer to bring cartilage biologists, synthetic chemists, biomechanical engineers, and 3D-bioprinting technologists together to expedite CTE process for eventual clinical applications.