Sequestration and Involucrum: Understanding Bone Necrosis and Revascularization in Pediatric Orthopedics.

Sequestration, a condition where a section of bone becomes necrotic due to a loss of vascularity or thrombosis, can be a challenging complication of osteomyelitis. This review explores the pathophysiology of sequestration, highlighting the role of the periosteum in forming involucrum and creeping substitution which facilitate revascularization and bone formation. The authors also discuss the induced membrane technique, a two-stage surgical procedure for cases of failed healing of sequestration. Future directions include the potential use of prophylactic anticoagulation and novel drugs targeting immunocoagulopathy, as well as the development of advanced imaging techniques and single-stage surgical procedures.

Primary and Revision Total Hip Arthroplasty in Patients With Pulmonary Hypertension: High Perioperative Mortality and Medical Complications.

BACKGROUND: Perioperative medical management during total hip arthroplasty (THA) is continuously improving, allowing an increasing number of medically complex patients to undergo total joint arthroplasty. This study examined mortalities, medical complications, implant survivorships, and clinical outcomes of THA in patients who have pulmonary hypertension (HTN). METHODS: We identified 638 patients who had pulmonary HTN and underwent 508 primary THAs and 191 revision THAs from 2000 to 2016 at a tertiary care center. Patients were followed up at regular intervals until death, revision surgery, or last clinical follow-up. Perioperative medical complications were individually reviewed. The risk of death was examined by calculating standardized mortality ratios and Cox proportional hazards regression models. Cumulative incidence analyses were used for reporting mortality, reoperation, and revision with death as a competing risk. RESULTS: The 90-day mortality was 1.8% and 3.1% for primary and revision THAs, respectively. The risk of death was approximately two-fold higher compared to primary (hazard ratio 2.69) and revision (hazard ratio 2.04) THA patients who did not have pulmonary HTN. Rate of medical complications within 90 days from surgery were 6.2% and 13.1% in primary and revision THAs, respectively. The 10-year cumulative incidence of any revision was 9% and 14% following primaries and revisions, respectively. CONCLUSION: Patients who had pulmonary HTN undergoing primary and revision THAs had an increased risk of death and experienced a high rate of medical complications within 90 days of surgery. Counseling of risks, medical optimization, and referral to medical centers expert at managing complex medical problems should be considered. LEVEL OF EVIDENCE: Level IV.

Pairing 40-mm Femoral Heads With the Smallest Compatible Acetabular Components in Total Hip Arthroplasty: Mid-Term Outcomes in 177 Cases.

BACKGROUND: Contemporary total hip arthroplasty (THA) often employs larger femoral heads to optimize hip stability. However, pairing 40-mm femoral heads with the smallest compatible acetabular components poses a potential risk for implant failure. The purpose of this study is to evaluate the outcomes of primary THAs using 40-mm femoral heads and the smallest compatible acetabular components. METHODS: Between 2007 and 2018, 177 primary THAs involving 40-mm femoral heads and acetabular components ≤56 mm with highly cross-linked polyethylene liners were identified. Mean age was 61 years, 56% were females, and mean body mass index was 32 kg/m2. Cumulative incidences of dislocation, any revision, and any reoperation were determined utilizing a competing risk model. Osteolysis and femoral head penetration were assessed at minimum 8-year follow-up (n = 16). Mean follow-up was 6 years. RESULTS: There were no cases of liner fractures or dissociations. The 10-year cumulative incidences of dislocation, any revision, and any reoperation were 3.6%, 4.2%, and 6.8%, respectively. Mean linear femoral head penetration was 0.01 mm/y and mean volumetric wear rate was 50 mm3/y. One THA demonstrated stable, asymptomatic periacetabular radiolucent lines at most recent follow-up. CONCLUSION: In 177 primary THAs pairing 40-mm femoral heads with the smallest compatible acetabular components, there were no liner fractures or dissociations. The cumulative incidence of dislocation was modest at 10 years. The cumulative incidences of any revision and any reoperation were low at mid-term. LEVEL OF EVIDENCE: IV.

Tiered Guidelines in a Pediatric Orthopaedic Practice Reduce Opioids Prescribed at Discharge.

BACKGROUND: Data regarding opioid prescribing patterns following pediatric orthopaedic procedures is limited. The aim of this work was to evaluate the effects of tiered guidelines for discharge opioid prescriptions following common pediatric orthopaedic procedures. METHODS: Quality improvement project conducted at a single academic institution. Guidelines for discharge opioid prescriptions were implemented January 2018 and established 4 tiers of increasing invasiveness for 28 common pediatric orthopaedic procedures. Patients who underwent these procedures in 2017 comprised the preguideline cohort (N=258), while patients treated in 2019 comprised the postguideline cohort (N=212). Opioid prescriptions were reported as oral morphine equivalents (OMEs). Univariate tests were performed to assess statistically significant differences before and after implementation of the guidelines. RESULTS: There was a significant decrease in OME prescribed between preguideline and postguideline cohorts (median OME 97.5 vs. 37.5). When analyzed according to procedure tiers, tiers 1, 2, and 4 showed significant decreases in OME prescribed between 2017 and 2019. The rate of no opioids prescribed at discharge increased from 13% to 23% between preguideline and postguideline cohorts. The 30-day refill rate did not significantly change. After implementation of guidelines, 91% of all prescriptions were within the guideline parameters, and there was a significant reduction in prescription variability. In tier 4 procedures, median OME prescribed decreased from 375 preguideline to 188 postguideline, but was associated with greater opioid refills within 30 days of discharge (10.2% preguideline vs. 28.8% postguideline). CONCLUSIONS: Tiered guidelines for discharge opioid prescriptions following pediatric orthopaedic procedures can significantly decrease the quantity of opioids prescribed. Furthermore, we noted excellent adherence and no overall increase in the rates of narcotic refills. Such guidelines may improve pediatric orthopaedists' ability to responsibly treat postoperative pain while limiting the distribution of unneeded opioids. LEVEL OF EVIDENCE: Level IV-quality improvement project.

Primary and Revision Total Knee Arthroplasty in Patients With Pulmonary Hypertension: High Perioperative Mortality and Complications.

BACKGROUND: Although perioperative medical management during total knee arthroplasty (TKA) has improved, there is limited literature characterizing outcomes of patients with pulmonary hypertension (HTN). This study examined mortality, medical complications, implant survivorship, and clinical outcomes in this medically complex cohort. METHODS: We identified 887 patients with pulmonary HTN who underwent 881 primary TKAs and 228 revision TKAs from 2000 to 2016 at a tertiary care center. Patients were followed up at regular intervals until death, revision surgery, or last clinical follow-up. Perioperative medical complications were individually reviewed. The risk of death was examined by calculating standardized mortality ratios and Cox proportional hazards regression models. Cumulative incidence analysis was used for reporting mortality, revision, and reoperation with death as a competing risk. RESULTS: The 90-day mortality was 0.7% and 4.8% for primary and revision TKAs, respectively. The risk of death was 2-fold higher compared to primary (hazard ratio 2.54, 95% confidence interval [CI] 2.12-3.05) and revision (hazard ratio 2.16, 95% CI 1.78-2.62) TKA patients without pulmonary HTN. Rate of medical complications within 90 days from surgery was 6.5% and 14% in primary and revision TKAs. The 10-year cumulative incidence of any revision was 5% and 16% in primaries and revisions, respectively. CONCLUSION: Patients with pulmonary HTN undergoing primary and revision TKAs had excess risk of death and experience a high rate of medical complications within 90 days of surgery. Counseling of risks, medical optimization, and referral to tertiary centers should be considered. LEVEL OF EVIDENCE: Level IV.

Anterior Vertebral Body Tethering for Adolescent Idiopathic Scoliosis: Early Results and Future Directions.

Anterior vertebral body tether (AVBT) is a nonfusion surgical procedure for correction of scoliosis in skeletally immature individuals. With US Food and Drug Administration approval in 2019, AVBT technology is spreading and early to midterm reports are being published. Early clinical reports are promising while precise indications, outcomes, complication profiles, and best practices are being established. Patients who are skeletally immature and wish to avoid a fusion surgery may benefit from this procedure. This article highlights the translational science foundation, early to midterm clinical reports, and future directions for this growing technique in pediatric spinal deformity surgery.

The Lawrence D. Dorr Surgical Techniques & Technologies Award: Using Big Heads and Small Acetabular Components With Highly Cross-Linked Polyethylene in Total Hip Arthroplasty: Is It Safe?

BACKGROUND: Contemporary total hip arthroplasty (THA) employs larger femoral heads to optimize hip stability. However, the combination of large femoral heads and comparatively small acetabular components poses a potential risk for implant failure secondary to polyethylene (PE) liner fracture or dissociation. The purpose of this study was to evaluate the incidence of liner fracture or dissociation, implant survivorship, and PE wear rates in primary THAs using large femoral heads and small acetabular components. METHODS: Between 2000 and 2017, we retrospectively identified 882 primary THAs with 36 mm femoral heads and acetabular components ≤52 mm with highly cross-linked polyethylene liners. Mean age was 66 years, 88% were females, and mean body mass index was 30 kg/m2. We evaluated the cumulative incidences of dislocation, any revision, and any reoperation utilizing a competing risk model. Osteolysis and femoral head penetration were assessed with a validated radiographic technique at minimum 10-year follow-up (n = 18). Mean follow-up was 4 years. RESULTS: There were no liner fractures or dissociations in the entire cohort. The 10-year cumulative incidences of dislocation, any revision, and any reoperation were 3.2%, 5.6%, and 9.3%, respectively. Mean linear femoral head penetration was 0.042 mm/y and mean volumetric wear rate was 44 mm3/y. No THAs demonstrated evidence of osteolysis or component loosening at long-term follow-up. CONCLUSION: In a large cohort of primary THAs pairing large femoral heads with small acetabular components, there was no evidence of liner fracture or dissociation. Cumulative incidences of dislocation, any revision, and any reoperation were low at mid-term. LEVEL OF EVIDENCE: IV.

Anterior vertebral body tethering shows mixed results at 2-year follow-up.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: To report 2-4-year outcomes of anterior vertebral body tethering (AVBT) for adolescent idiopathic scoliosis (AIS). AVBT is a relatively new procedure to correct AIS spine curvature and few outcomes studies have been published. METHODS: Patients from 2015 to 2017 with 2-year follow-up were included. Successful outcomes were defined as curves 35° or less without revision surgery. We also compared outcomes between thoracic and lumbar ABVT. RESULTS: There were 19 AVBTs in 17 patients, 13 thoracic and 6 lumbar. Nine curves (47%) in nine patients (53%) were successful. Preoperative kyphosis averaged 26° in the successful group and 14° in the unsuccessful group (P = 0.0337). Immediate correction for lumbar ABVTs (76%) was greater than thoracic ABVTs (43%) (P = 0.0140). Correction per level per month was greater in lumbar ABVTs (2.9° vs. 0.1°) (0.0440). Preoperative Sanders Maturity Scale (SMS) was 3.7 for successful cases and 2.5 for unsuccessful cases (P = 0.0232). Final SMS was 7.7 for successful cases and 5.7 for unsuccessful cases (P = 0.0518). All successful cases and 50% of unsuccessful cases were mature at final follow-up (P = 0.0294). There were four (24%) revision procedures, and three involving lumbar AVBTs. There were nine (47%) broken tethers. CONCLUSIONS: Despite several final curves > 35°, four revisions, and nine broken tethers, the majority of patients (53%) were considered successful. Lumbar ABVTs correct more intraoperatively and faster postoperatively. Patients who are tethered during or slightly after the curve acceleration phase of growth may have more successful outcomes than patients tethered prior to the curve acceleration phase. AVBT requires further study with longer outcomes to define best practices for indications, level selections, and surgical techniques. LEVEL OF EVIDENCE: IV.

Pediatric Seymour Fractures of the Toe.

BACKGROUND: Seymour fractures of the toe are physeal fractures with often occult concomitant nail bed injuries and thus are open fractures. They are uncommon injuries that without proper treatment can result in osteomyelitis. The literature has sparse information regarding the clinical outcomes for these injuries. METHODS: A single-center retrospective review included juxta-epiphyseal fractures or Salter-Harris I/II fracture of the toe with documented concomitant nail bed injury or laceration. Clinical and radiographic data were recorded for consecutive fractures. The primary outcome was the incidence of osteomyelitis. Secondary outcomes included premature physeal arrest, development of nail dystrophy, and functionality of the toe. RESULTS: Between 2006 and 2019, 19 patients were treated for this injury by the pediatric orthopaedic division. Complications included osteomyelitis (n=6), physeal arrest (n=4), and nail dystrophy (n=1). Days from injury to definitive treatment were significantly greater in patients who developed osteomyelitis compared with those who did not (P<0.01). Patients were significantly more likely to develop osteomyelitis if they did not receive acute definitive treatment (<48 h) (P<0.001; likelihood ratio, 17.9). CONCLUSIONS: Prompt definitive treatment of Seymour fractures of the toe was associated with a lower incidence of osteomyelitis. Greater awareness for these seemingly innocuous injuries is needed to provide an early treatment that may reduce the rate of osteomyelitis. LEVEL OF EVIDENCE: Level IV-case series.

Knotless Arthroscopic Repair of Subscapularis Avulsion Fracture Using a Single Anterior Portal.

Proximal humerus lesser tuberosity avulsions are uncommon injuries; however, when present, they can be debilitating for patients. As such, they pose a unique clinical challenge. These fractures were traditionally treated through an open approach to the proximal humerus; however, arthroscopic techniques continue to evolve and are increasingly used for these types of injuries. We describe our minimally invasive arthroscopic technique to repair lesser tuberosity avulsions using standard arthroscopic equipment. This method is safe, efficient, and applies basic shoulder arthroscopic techniques.

Dilutional coagulopathy in pediatric scoliosis surgery: A single center report.

BACKGROUND: Children undergoing posterior spinal fusion experience high blood loss often necessitating transfusion. An appropriately activated coagulation system provides hemostasis during surgery, but pathologic dysregulation can cause progressive bleeding and increased transfusions. Despite receiving antifibrinolytics for clot stabilization, many patients still require transfusions. AIMS: We sought to examine the association of dilutional coagulopathy with blood loss and blood transfusion in posterior spinal fusion for pediatric scoliosis patients. METHODS: A retrospective, single institution study of children undergoing posterior spinal fusion >6 levels with a standardized, prospective anesthetic protocol utilizing antifibrinolytics. Blood loss was evaluated using a hematocrit-based calculation. To evaluate transfusions, a normalized Blood Product Transfusion calculation was developed. Factors associated with blood loss and blood transfusions were determined by univariate analysis and multivariate regression modeling with multicollinearity and mediation analysis. RESULTS: Patients received 73.7 mL/kg (standard deviation ±30.8) of fluid poor in coagulation factors. Estimated blood loss was 42.6 mL/kg (standard deviation ±18.0). There was a significant association between estimated blood loss and total fluids delivered (Spearman's rho = 0.51, 95% confidence interval 0.33-0.65, P < 0.001). Factors significantly associated with normalized Blood Product Transfusion in this cohort included age, weight, scoliosis type, levels fused, total osteotomies, pelvic fixation, total fluid, maximum prothrombin time, and minimum fibrinogen. Regression modeling showed the best combination of variables for modeling normalized Blood Product Transfusion included patient weight, number of levels fused, total fluid administered, and maximum prothrombin time. CONCLUSION: Blood product transfusion remains a frustrating problem in pediatric scoliosis. Identifying and controlling dilutional coagulopathy in these patients may reduce blood loss and the need for blood transfusion.

Bone Fracture Acute Phase Response-A Unifying Theory of Fracture Repair: Clinical and Scientific Implications.

Bone fractures create five problems that must be resolved: bleeding, risk of infection, hypoxia, disproportionate strain, and inability to bear weight. There have been enormous advancements in our understanding of the molecular mechanisms that resolve these problems after fractures, and in best clinical practices of repairing fractures. We put forth a modern, comprehensive model of fracture repair that synthesizes the literature on the biology and biomechanics of fracture repair to address the primary problems of fractures. This updated model is a framework for both fracture management and future studies aimed at understanding and treating this complex process. This model is based upon the fracture acute phase response (APR), which encompasses the molecular mechanisms that respond to injury. The APR is divided into sequential stages of "survival" and "repair." Early in convalescence, during "survival," bleeding and infection are resolved by collaborative efforts of the hemostatic and inflammatory pathways. Later, in "repair," avascular and biomechanically insufficient bone is replaced by a variable combination of intramembranous and endochondral ossification. Progression to repair cannot occur until survival has been ensured. A disproportionate APR-either insufficient or exuberant-leads to complications of survival (hemorrhage, thrombosis, systemic inflammatory response syndrome, infection, death) and/or repair (delayed- or non-union). The type of ossification utilized for fracture repair is dependent on the relative amounts of strain and vascularity in the fracture microenvironment, but any failure along this process can disrupt or delay fracture healing and result in a similar non-union. Therefore, incomplete understanding of the principles herein can result in mismanagement of fracture care or application of hardware that interferes with fracture repair. This unifying model of fracture repair not only informs clinicians how their interventions fit within the framework of normal biological healing but also instructs investigators about the critical variables and outputs to assess during a study of fracture repair.

Medical Students' Perspectives on Implementing Curriculum Change at One Institution.

Training physicians to be effective practitioners throughout their careers begins in undergraduate medical education with particular focus on self-directed inquiry, professional and interprofessional development, and competency-based assessment. A select number of medical schools are restructuring their curricula by placing the student at the center of content delivery to enhance the learning experience. While this restructuring may benefit the adult learner, administrators often make assumptions about how students will perceive and respond to such innovative and unfamiliar educational concepts. This can create a disconnect between students and their curriculum. Administrative mindfulness of student experiences is needed to ensure successful implementation of curricular change, facilitate the transition from old to new modalities, and train competent physician graduates.Vanderbilt University School of Medicine (VUSM) recently completed a curriculum update, and student representatives have been essential participants in the transition, from the earliest stages in preplanning to rapid-cycle feedback as the curriculum runs. Two of the authors are members of VUSM's Student Curriculum Committee, which facilitates gathering and relaying student feedback to the administration. Drawing from their experiences, five specific considerations to address and manage when implementing student-centered curricular change are presented: (1) Communicate the rationale, (2) acknowledge anxiety, (3) adjust extracurricular leadership roles, (4) manage "The Bulge" of learners in the clinical environment, and (5) foster ongoing collaboration of students and administrators. For each consideration, examples and proposed solutions are provided.

Plasmin Prevents Dystrophic Calcification After Muscle Injury.

Extensive or persistent calcium phosphate deposition within soft tissues after severe traumatic injury or major orthopedic surgery can result in pain and loss of joint function. The pathophysiology of soft tissue calcification, including dystrophic calcification and heterotopic ossification (HO), is poorly understood; consequently, current treatments are suboptimal. Here, we show that plasmin protease activity prevents dystrophic calcification within injured skeletal muscle independent of its canonical fibrinolytic function. After muscle injury, dystrophic calcifications either can be resorbed during the process of tissue healing, persist, or become organized into mature bone (HO). Without sufficient plasmin activity, dystrophic calcifications persist after muscle injury and are sufficient to induce HO. Downregulating the primary inhibitor of plasmin (α2-antiplasmin) or treating with pyrophosphate analogues prevents dystrophic calcification and subsequent HO in vivo. Because plasmin also supports bone homeostasis and fracture repair, increasing plasmin activity represents the first pharmacologic strategy to prevent soft tissue calcification without adversely affecting systemic bone physiology or concurrent muscle and bone regeneration. © 2016 American Society for Bone and Mineral Research.