The Digital Therapeutics Real-World Evidence Framework: An Approach for Guiding Evidence-Based Digital Therapeutics Design, Development, Testing, and Monitoring.

Digital therapeutics (DTx) are a promising way to provide safe, effective, accessible, sustainable, scalable, and equitable approaches to advance individual and population health. However, developing and deploying DTx is inherently complex in that DTx includes multiple interacting components, such as tools to support activities like medication adherence, health behavior goal-setting or self-monitoring, and algorithms that adapt the provision of these according to individual needs that may change over time. While myriad frameworks exist for different phases of DTx development, no single framework exists to guide evidence production for DTx across its full life cycle, from initial DTx development to long-term use. To fill this gap, we propose the DTx real-world evidence (RWE) framework as a pragmatic, iterative, milestone-driven approach for developing DTx. The DTx RWE framework is derived from the 4-phase development model used for behavioral interventions, but it includes key adaptations that are specific to the unique characteristics of DTx. To ensure the highest level of fidelity to the needs of users, the framework also incorporates real-world data (RWD) across the entire life cycle of DTx development and use. The DTx RWE framework is intended for any group interested in developing and deploying DTx in real-world contexts, including those in industry, health care, public health, and academia. Moreover, entities that fund research that supports the development of DTx and agencies that regulate DTx might find the DTx RWE framework useful as they endeavor to improve how DTxcan advance individual and population health.

Female Gender Is Associated with Lower Satisfaction with Postoperative Telemedicine Visits in Sports Medicine.

Introduction: Telemedicine is a relatively new adjunct in orthopedic care but it has emerged from the periphery, driven in part by the COVID-19 pandemic. Although it has drastically increased in use, little is known of the factors that drive satisfaction with telemedicine. The purpose of the current study was to evaluate the patient's satisfaction with postoperative telemedicine visits in those undergoing knee or shoulder arthroscopy, and to analyze the factors associated with satisfaction with telemedicine. Methods: A prospective study was performed to evaluate satisfaction comparing postoperative telemedicine and in-office visits, in those undergoing shoulder and knee arthroscopy. Multiple factors were analyzed for correlation with satisfaction via multi-linear regression, including demographics such as gender, education, age, and race. Patients were also evaluated for preference for future visits with reference to the group in which they were placed. Results: Overall, 215 patients were included with a subgroup analysis of 93 patients receiving telemedicine visits. Patients reported overall similar satisfaction with telemedicine visits after shoulder and knee arthroscopy, with a high level of satisfaction seen in both. Female sex was found to be associated with decreasing satisfaction with telemedicine visits (p = 0.036). In addition, as a whole, the cohort was found to prefer future visits to be the same as the group they were placed in, but females statistically did not have this preference for their familiar group and were skewed toward the preference of in-person visits (p = 0.377). Conclusions: Our study found that female patients were less likely to be satisfied with postoperative telemedicine visits after knee or shoulder arthroscopy. Further, females were also less likely to indicate preference for future telemedicine visits. In contrast, education, history of prior surgery, age, and race were not associated with postoperative satisfaction.

Anterior Cruciate Ligament Repair Using a Knotless Suture Implant.

Recent orthopedic literature has shown that primary repair for femoral-sided avulsion tears of the anterior cruciate ligament (ACL) can be successful. Primary ACL repair avoids invasive reconstruction techniques, graft-site morbidity, and the loss of native anatomy while producing excellent results in appropriately selected patients. Here we describe our patient selection parameters, ACL repair technique, and rehabilitation protocol.

Retrospective Study of Midazolam Protocol for Prehospital Behavioral Emergencies.

INTRODUCTION: Agitated patients in the prehospital setting pose challenges for both patient care and emergency medical services (EMS) provider safety. Midazolam is frequently used to control agitation in the emergency department setting; however, limited data exist in the prehospital setting. We describe our experience treating patients with midazolam for behavioral emergencies in a large urban EMS system. We hypothesized that using midazolam for acute agitation leads to improved clinical conditions without causing significant clinical deterioration. METHODS: We performed a retrospective review of EMS patient care reports following implementation of a behavioral emergencies protocol in a large urban EMS system from February 2014-June 2016. For acute agitation, paramedics administered midazolam 1 milligram (mg) intravenous (IV), 5 mg intramuscular (IM), or 5 mg intranasal (IN). Results were analyzed using descriptive statistics, Levene's test for assessing variance among study groups, and t-test to evaluate effectiveness based on route. RESULTS: In total, midazolam was administered 294 times to 257 patients. Median age was 30 (interquartile range 24-42) years, and 66.5% were male. Doses administered were 1 mg (7.1%) and 5 mg (92.9%). Routes were IM (52.0%), IN (40.8%), and IV (7.1%). A second dose was administered to 37 patients. In the majority of administrations, midazolam improved the patient's condition (73.5%) with infrequent adverse events (3.4%). There was no significant difference between the effectiveness of IM and IN midazolam (71.0% vs 75.4%; p = 0.24). CONCLUSION: A midazolam protocol for prehospital agitation was associated with reduced agitation and a low rate of adverse events.

Editorial Commentary: Anterior Cruciate Ligament Injury and Reconstruction in Soccer Players: The Major Challenge Is Always Going for Our Goals!

Anterior cruciate ligament (ACL) injury affects a large number of athletes worldwide, and long-term rate of return to soccer is approximately 50% or less. ACL injury, which is noncontact in approximately 90% of cases, has a complex multifactorial etiology. Younger and higher-level players do better, and 10-year outcomes are superior to baseline. The role of genomics, hormonal status, neuromuscular deficiencies, anatomy, and the environment are all potential contributory risk factors that vary with respect to the individual, especially the female athlete. Furthermore, ACL injury results in a local and regional catabolic cascade and cytokine release, creating an intra-articular environment that is a homeostatic perfect storm and spectrum of scalable articular cartilage and meniscal injury. Once these complexities in the knee organ are defined and understood, the surgeon's early objectives are stabilization, repair, and restoration with full harmonization of biomechanics, neuromuscular control, and homeostasis. The goal is optimizing long-term outcomes, decreasing the rate of subsequent ACL injury, and preventing osteoarthritis.

The Center-Center Technique for the Direct Anterior Approach in Total Hip Arthroplasty: Precise Femoral Canal Preparation to Optimize Implant Fit and Fill.

BACKGROUND: The use of the direct anterior approach has been criticized as a significant risk factor for subsidence, perioperative fracture, and thigh pain. Therefore, the purpose of our study was to evaluate the outcome of using the center-center technique via the direct anterior approach. MATERIALS AND METHODS: Consecutive elective primary total hip arthroplasties performed using the center-center technique were retrospectively reviewed from May 2015 to February 2017. All cases were performed by a single surgeon at a high-volume, large academic center. The technique focuses on central alignment of the implant on both anteroposterior and lateral radiographs. Standardized objective radiographic measurements were taken at the first two-week follow-up visit to determine the fit and fill at the proximal and distal anatomic segments. Subsidence was measured by comparing the implant position at final follow up to the initial two-week postoperative visit. Other complications: intra- or postoperative fracture, infection, revision, and patient-reported thigh pain were further assessed. Functional postoperative outcomes were assessed using the Harris Hip Score (HHS). RESULTS: A total of 138 patients with a mean age of 65 years and average follow up of 2.8 years were assessed. The mean postoperative HHS was 90 points (59-100). Mean implant subsidence was 1mm. A total of 90% (124) of implants had acceptable radiographic fit and fill in both proximal and distal segments. A majority 74% (102) of implants subsided less than 1mm, and 91% (126) subsided less than 2mm. One implant had radiographic subsidence of 9mm, which was treated with a shoe lift. There were no intraoperative fractures. One postoperative lateral cortex fracture three weeks after surgery due to mechanical fall was treated conservatively. No patients required revision arthroplasty for any reason or reported postoperative thigh pain. CONCLUSION: The center-center technique can be used to consistently aid in proper femoral stem placement in both coronal and sagittal planes. Optimal fit and fill can be achieved safely using this technique.

Large urban center improves out-of-hospital cardiac arrest survival.

BACKGROUND: Large cities pose unique challenges that limit the effectiveness of system improvement interventions. Successful implementation of integrated cardiac resuscitation systems of care can serve as a model for other urban centers. METHODS: This was a retrospective analysis of prospectively collected data of adult cases of non-traumatic cardiac arrest who received treatment by Chicago Fire Department EMS from September 1, 2013 through December 31, 2016. We measured temporal OHCA outcomes during implementation of system-wide initiatives including telephone-assisted and community CPR training programs; high performance CPR and team based simulation training; new post resuscitation care and destination protocols; and case review for EMS providers. Outcomes measured included bystander CPR rates, return of spontaneous circulation (ROSC), hospital admission and survival, and favorable neurologic outcomes (CPC 1-2). Relative risk was determined by logistic regression model where observed group-specific outcomes are expressed as odds ratios (OR). RESULTS: We included 6103 adult OHCA cases occurring outside of health care facilities from September 1, 2013 through December 31, 2016. Significantly improved outcomes (p < 0.05) were observed between 2013 and 2016 for bystander CPR (11.6% vs 19.4%), ROSC (28.6% vs 36.9%), hospital admission (22.5% vs 29.4%), survival (7.3% vs 9.9%), and CPC 1-2 (4.3% vs 6.4%). Utstein survival increased from 16.3%-35.4% and CPC 1-2 survival from 11.6%-29.1% (p < 0.05). After adjustment for OHCA characteristics, survival with CPC 1-2 increased over time (OR 1.15, p = 0.0277). CONCLUSIONS: Densely populated cities with low survival rates can overcome systematic challenges and improve OHCA survival.

Iatrogenic Obturator Hip Dislocation with Intrapelvic Migration.

Obturator hip dislocations are rare, typically resulting from high-energy trauma in native hips. These types of dislocations are treated with closed reduction under sedation. Open reduction and internal fixation may be performed in the presence of associated fractures. Still rarer are obturator hip dislocations that penetrate through the obturator foramen itself. These types of dislocations have only been reported three other times in the literature, all within native hips. To date, there have been no reports of foraminal obturator dislocations after total hip arthroplasty. We report of the first periprosthetic foraminal obturator hip dislocation, which was caused iatrogenically during attempts at closed reduction of a posterior hip dislocation in the setting of a chronic greater trochanter fracture. Altered joint biomechanics stemming from a weak hip abductor mechanism rendered the patient vulnerable to this specific dislocation subtype, which ultimately required open surgical intervention. An early assessment and identification of this dislocation prevented excessive closed reduction maneuvers, which otherwise could have had detrimental consequences including damage to vital intrapelvic structures. This case report raises awareness to this very rare, yet potential complication after total hip arthroplasty.

Cincinnati Prehospital Stroke Scale Can Identify Large Vessel Occlusion Stroke.

OBJECTIVE: Accurate prehospital identification of patients with acute ischemic stroke (AIS) from large vessel occlusion (LVO) facilitates direct transport to hospitals that perform endovascular thrombectomy. We hypothesize that a cut-off score of the Cincinnati Prehospital Stroke Scale (CPSS), a simple assessment tool currently used by emergency medical services (EMS) providers, can be used to identify LVO. METHODS: Consecutively enrolled, confirmed AIS patients arriving via EMS between August 2012 and April 2014 at a high-volume stroke center in a large city with a single municipal EMS provider agency were identified in a prospective, single-center registry. Head and neck vessel imaging confirmed LVO. CPSS scores were abstracted from prehospital EMS records. Spearman's rank correlation, Wilcoxon rank-sum test, and Student's t-test were performed. Cohen's kappa was calculated between CPSS abstractors. The Youden index identified the optimal CPSS cut-off. Multivariate logistic regression controlling for age, sex, and race determined the odds ratio (OR) for LVO. RESULTS: Of 144 eligible patients, 138 (95.8%) had CPSS scores in the EMS record and were included for analysis. The median age was 69 (IQR 58-81) years. Vessel imaging was performed in 97.9% of patients at a median of 5.9 (IQR 3.6-10.2) hours from hospital arrival, and 43.7% had an LVO. Intravenous tissue plasminogen activator was administered to 29 patients, in whom 12 had no LVO on subsequent vessel imaging. The optimal CPSS cut-off predicting LVO was 3, with a Youden index of 0.29, sensitivity of 0.41, and specificity of 0.88. The adjusted OR for LVO with CPSS = 3 was 5.7 (95% CI 2.3-14.1). Among patients with CPSS = 3, 72.7% had an LVO, compared with 34.3% of patients with CPSS ≤ 2 (p < 0.0001). CONCLUSIONS: A CPSS score of 3 reliably identifies LVO in AIS patients. EMS providers may be able to use the CPSS, a simple, widely adopted prehospital stroke assessment tool, with a cut-off score to screen for patients with suspected LVO.

A Novel Approach to Improving Patient Experience in Orthopedics.

The patient experience domain comprises a significant portion of the Hospital Value-Based Purchasing program. This study investigated whether an intervention focusing on attending physician awareness, resident and physician assistant education, and multidisciplinary patient-centric care had an effect on patient perceived physician communication and overall hospital ratings. Responses to the Hospital Consumer Assessment of Healthcare Providers and Systems survey were reviewed in 2014 and 2015. Patients' perceptions that the physician explained their condition in ways they understood and the overall hospital rating improved significantly after implantation of the model ( P < .05). Patient-physician communication is important for high-quality health care and is becoming increasingly more important in hospital economics. These methods may serve as a protocol for other institutions to improve the patient experience.

Identifying Key Words in 9-1-1 Calls for Stroke: A Mixed Methods Approach.

OBJECTIVES: Identifying stroke during a 9-1-1 call is critical to timely prehospital care. However, emergency medical dispatchers (EMDs) recognize stroke in less than half of 9-1-1 calls, potentially due to the words used by callers to communicate stroke signs and symptoms. We hypothesized that callers do not typically use words and phrases considered to be classical descriptors of stroke, such as focal neurologic deficits, but that a mixed-methods approach can identify words and phrases commonly used by 9-1-1 callers to describe acute stroke victims. METHODS: We performed a mixed-method, retrospective study of 9-1-1 call audio recordings for adult patients with confirmed stroke who were transported by ambulance in a large urban city. Content analysis, a qualitative methodology, and computational linguistics, a quantitative methodology, were used to identify key words and phrases used by 9-1-1 callers to describe acute stroke victims. Because a caller's level of emotional distress contributes to the communication during a 9-1-1 call, the Emotional Content and Cooperation Score was scored by a multidisciplinary team. RESULTS: A total of 110 9-1-1 calls, received between June and September 2013, were analyzed. EMDs recognized stroke in 48% of calls, and the emotional state of most callers (95%) was calm. In 77% of calls in which EMDs recognized stroke, callers specifically used the word "stroke"; however, the word "stroke" was used in only 38% of calls. Vague, non-specific words and phrases were used to describe stroke victims' symptoms in 55% of calls, and 45% of callers used distractor words and phrases suggestive of non-stroke emergencies. Focal neurologic symptoms were described in 39% of calls. Computational linguistics identified 9 key words that were more commonly used in calls where the EMD identified stroke. These words were concordant with terms identified through qualitative content analysis. CONCLUSIONS: Most 9-1-1 callers used vague, non-specific, or distractor words and phrases and infrequently provide classic stroke descriptions during 9-1-1 calls for stroke. Both qualitative and quantitative methodologies identified similar key words and phrases associated with accurate EMD stroke recognition. This study suggests that tools incorporating commonly used words and phrases could potentially improve EMD stroke recognition.

EMS Provider Perceptions on Termination of Resuscitation in a Large, Urban EMS System.

OBJECTIVE: Despite the value of out-of-hospital Termination of Resuscitation (TOR) and the scientific evidence in favor of this practice, TOR has not been uniformly adopted or consistently practiced in EMS systems. Previous focus group studies have identified multiple barriers to implementation of out of hospital TOR but existing literature on EMS provider perceptions is limited. We sought to identify EMS providers' perceived barriers to performing out-of-hospital TOR in a large urban EMS system. METHODS: The Chicago EMS System is a regional collaborative of EMS physicians, nurses and provider agencies, including the Chicago Fire Department (CFD), which provides exclusive emergency response for 9-1-1 calls in Chicago. CFD is an urban, fire-based EMS agency with a tiered response, with fire-fighter EMTs and paramedics providing initial care, and single role paramedics providing supplemental care and transport. A 2-page written survey was distributed to understand providers' experiences with managing OHCA and perceived barriers to TOR to inform subsequent improvements in protocol development and education. RESULTS: Of 3500 EMS providers that received the survey, 2309 were completed (66%). Survey respondent demographics were fire-fighter/EMTB (69%), fire-fighter/paramedic (14%), and single role paramedic (17%). The most frequent barrier to field TOR was scene safety (86%). The most common safety issue identified was family reaction to TOR (68%) and many providers felt threatened by family when trying to perform TOR (38%). Providers with a higher career numbers of OHCA were more likely to have felt threatened by the family (OR 6.70, 95% CI 2.99-15.00) and single role paramedics were more likely than FF/EMTBs to have felt threatened (OR 3.34, 95% CI 2.65-4.22). Barriers to delivering a death notification after TOR, include being uncomfortable or threatened with possible family reaction (52%) and family asking to continue the resuscitation (45%). There was lack of formal prior death notification training, the majority learned from colleagues through on the job training. CONCLUSIONS: Our study identifies scene safety, death notification delivery, and lack of formal training in death notification as barriers that EMS providers face while performing TOR in a large urban EMS system. These findings informed educational and operational initiatives to overcome the identified provider level issues and improve compliance with TOR policies.

Patients' perceptions of care are associated with quality of hospital care: a survey of 4605 hospitals.

Favorable patient experience and low complication rates have been proposed as essential components of patient-centered medical care. Patients' perception of care is a key performance metric and is used to determine payments to hospitals. It is unclear if there is a correlation between technical quality of care and patient satisfaction. The study authors correlated patient perceptions of care measured by the Hospital Consumer Assessment of Healthcare Providers and Systems scores with accepted quality of care indicators. The Hospital Compare database (4605 hospitals) was used to examine complication rates and patient-reported experience for hospitals across the nation in 2011. The majority of the correlations demonstrated an inverse relationship between patient experience and complication rates. This negative correlation suggests that reducing these complications can lead to a better hospital experience. Overall, these results suggest that patient experience is generally correlated with the quality of care provided.

Antibiotic stewardship in orthopaedic surgery: principles and practice.

A thorough knowledge of the principles of antibiotic stewardship is a crucial part of high-quality orthopaedic surgical care. These principles include (1) determining appropriate indications for antibiotic administration, (2) choosing the correct antibiotic based on known or expected pathogens, (3) determining the correct dosage, and (4) determining the appropriate duration of treatment. Antibiotic stewardship programs have a multidisciplinary staff that can help guide antibiotic selection and dosage. These programs also perform active surveillance of antimicrobial use and may reduce Clostridium difficile and other drug-resistant bacterial infections by providing expert guidance on judicious antibiotic usage. The emergence of antibiotic-resistant pathogens, the geographical diversity of these infecting pathogens, and the changing patient population require customization of prophylactic regimens to reduce infectious complications. A multidisciplinary approach to antibiotic stewardship can lead to improved patient outcomes and cost-effective medical care.

Measuring quality in orthopaedic surgery: the use of metrics in quality management.

There has been a substantial shift in the assessment of outcomes in medicine, including orthopaedic surgery. The quality movement is redefining the delivery of health care. The effect of these changes on orthopaedic surgery and orthopaedic surgeons has been significant and will become increasingly important. Orthopaedic surgeons must become active participants in the quality movement by understanding the basic principles of the movement and how they apply to patient care. A clear understanding of the different agencies (governmental and private) that are leading these initiatives is also essential. Ultimately, active participation in the quality movement will enhance the care provided to patients with musculoskeletal disorders.

Prehospital triage to primary stroke centers and rate of stroke thrombolysis.

IMPORTANCE: Implementation of prehospital stroke triage is a public policy intervention that can have an immediate impact on acute stroke care in a region. OBJECTIVE To evaluate the impact that a citywide policy recommending prehospital triage of patients with suspected stroke to the nearest primary stroke center had on intravenous tissue plasminogen activator (tPA) use in Chicago, Illinois. DESIGN: Retrospective multicenter cohort study from September 1, 2010, to August 31, 2011 (6 months before and after intervention that began March 1, 2011). SETTING: Ten primary stroke center hospitals in Chicago. PATIENTS: All admitted patients with stroke and transient ischemic attack. INTERVENTION Prehospital triage policy of patients with stroke to primary stroke centers. MAIN OUTCOMES AND MEASURES: Intravenous tPA use (measured as a fraction of patients with ischemic strokes arriving through the emergency department). RESULTS There were 1075 stroke and transient ischemic attack admissions in the pretriage period and 1172 in the posttriage period. Patient demographic characteristics including age, sex, and risk factors were similar between the 2 periods (mean age, 65 years; 53% female). Compared with the pretriage period, use of emergency medical services increased from 30.2% to 38.1% (P < .001) and emergency medical services prenotification increased from 65.5% to 76.5% (P = .001) after implementation. Rates of intravenous tPA use were 3.8% and 10.1% (P < .001) and onset-to-treatment times decreased from 171.7 to 145.7 minutes (P = .03) in the pretriage and posttriage periods, respectively. Stroke unit admission, symptomatic intracranial hemorrhage rates, and in-hospital mortality were not significantly different between periods. Adjusting for mode of arrival, prehospital notification, and onset-to-arrival time, the posttriage period was independently associated with increased tPA use for patients with ischemic stroke presenting through the emergency department (adjusted odds ratio = 2.21; 95% CI, 1.34-3.64). CONCLUSIONS AND RELEVANCE: Implementation of a prehospital stroke triage policy in Chicago resulted in significant improvements in emergency medical services use and prenotification and more than doubled intravenous tPA use at primary stroke centers.

The effect of prehospital nebulized naloxone on suspected heroin-induced bronchospasm.

BACKGROUND: Snorting or smoking heroin is a known trigger of acute asthma exacerbation. Heroin abuse may be a risk factor for more severe asthma exacerbations and intubation. Heroin and other opioids provoke pulmonary bronchoconstriction. Naloxone may play a role in decreasing opioid-induced bronchospasm. There are no known clinical cases describing the effect of naloxone on opioid-induced bronchospasm. METHODS: This is an observational study in which nebulized naloxone was administered to patients with suspected heroin-induced bronchospasm. Patients with spontaneous respirations were administered 2 mg of naloxone with 3 mL of normal saline by nebulization. We describe a case series of administrations for suspected heroin-induced bronchospasm. RESULTS: We reviewed 21 administrations of nebulized naloxone to patients with suspected heroin-induced bronchospasm. Of these, 19 patients had a clinical response to treatment documented. Thirteen patients displayed clinical improvement (68%), 4 patients had no improvement (21%), and 2 patients worsened (10%). Of the 2 patients who had clinical decline, none required intubation. Of the patients who improved, 1 patient received only nebulized naloxone and 1 patient received naloxone and albuterol together. Seven patients showed clinical improvement after the administration of albuterol, atrovent, and naloxone together as a combination. Four patients showed additional improvement when the naloxone was administered after the albuterol and atrovent combination. CONCLUSION: Naloxone may play a role in reducing acute opioid-induced bronchoconstriction, either alone or in combination with albuterol. Future controlled studies should be conducted to determine if the addition of naloxone to standard treatment improves bronchospasm without causing adverse effects.

Advances in the Surgical Management of Articular Cartilage Defects: Autologous Chondrocyte Implantation Techniques in the Pipeline.

OBJECTIVE: The purpose of this review is to gain insight into the latest methods of articular cartilage implantation (ACI) and to detail where they are in the Food and Drug Administration approval and regulatory process. DESIGN: A PubMed search was performed using the phrase "Autologous Chondrocyte Implantation" alone and with the words second generation and third generation. Additionally, clinicaltrials.gov was searched for the names of the seven specific procedures and the parent company websites were referenced. RESULTS: Two-Stage Techniques: BioCart II uses a FGF2v1 culture and a fibrinogen, thrombin matrix, whereas Hyalograft-C uses a Hyaff 11 matrix. MACI uses a collagen I/III matrix. Cartipatch consists of an agarose-alginate hydrogel. Neocart uses a high-pressure bioreactor for culturing with a type I collagen matrix. ChondroCelect makes use of a gene expression analysis to predict chondrocyte proliferation and has demonstrated significant clinical improvement, but failed to show superiority to microfracture in a phase III trial. One Step Technique: CAIS is an ACI procedure where harvested cartilage is minced and implanted into a matrix for defect filling. CONCLUSION: As full thickness defects in articular cartilage continue to pose a challenge to treat, new methods of repair are being researched. Later generation ACI has been developed to address the prevalence of fibrocartilage with microfracture and the complications associated with the periosteal flap of first generation ACI such as periosteal hypertrophy. The procedures and products reviewed here represent advances in tissue engineering, scaffolds and autologous chondrocyte culturing that may hold promise in our quest to alter the natural history of symptomatic chondral disease.