Passaged Articular Chondrocytes From the Superficial Zone and Deep Zone Can Regain Zone-Specific Properties After Redifferentiation.

BACKGROUND: Bioengineered cartilage is a developing therapeutic to repair cartilage defects. The matrix must be rich in collagen type II and aggrecan and mechanically competent, withstanding compressive and shearing loads. Biomechanical properties in native articular cartilage depend on the zonal architecture consisting of 3 zones: superficial, middle, and deep. The superficial zone chondrocytes produce lubricating proteoglycan-4, whereas the deep zone chondrocytes produce collagen type X, which allows for integration into the subchondral bone. Zonal and chondrogenic expression is lost after cell number expansion. Current cell-based therapies have limited capacity to regenerate the zonal structure of native cartilage. HYPOTHESIS: Both passaged superficial and deep zone chondrocytes at high density can form bioengineered cartilage that is rich in collagen type II and aggrecan; however, only passaged superficial zone-derived chondrocytes will express superficial zone-specific proteoglycan-4, and only passaged deep zone-derived chondrocytes will express deep zone-specific collagen type X. STUDY DESIGN: Controlled laboratory study. METHODS: Superficial and deep zone chondrocytes were isolated from bovine joints, and zonal subpopulations were separately expanded in 2-dimensional culture. At passage 2, superficial and deep zone chondrocytes were seeded, separately, in scaffold-free 3-dimensional culture within agarose wells and cultured in redifferentiation media. RESULTS: Monolayer expansion resulted in loss of expression for proteoglycan-4 and collagen type X in passaged superficial and deep zone chondrocytes, respectively. By passage 2, superficial and deep zone chondrocytes had similar expression for dedifferentiated molecules collagen type I and tenascin C. Redifferentiation of both superficial and deep zone chondrocytes led to the expression of collagen type II and aggrecan in both passaged chondrocyte populations. However, only redifferentiated deep zone chondrocytes expressed collagen type X, and only redifferentiated superficial zone chondrocytes expressed and secreted proteoglycan-4. Additionally, redifferentiated deep zone chondrocytes produced a thicker and more robust tissue compared with superficial zone chondrocytes. CONCLUSION: The recapitulation of the primary phenotype from passaged zonal chondrocytes introduces a novel method of functional bioengineering of cartilage that resembles the zone-specific biological properties of native cartilage. CLINICAL RELEVANCE: The recapitulation of the primary phenotype in zonal chondrocytes could be a possible method to tailor bioengineered cartilage to have zone-specific expression.

Martial Arts: Orthopaedic Injuries and Related Biomechanics.

Martial arts are various systems of combat skills encompassing striking and grappling. Many styles have evolved into modern sports, and some have been included in the Olympics. The physicality of these can predispose practitioners to musculoskeletal injuries, such as anterior cruciate ligament ruptures; patellar, shoulder, or elbow instabilities; extremity fractures; and hand and spine injuries, which have been studied both clinically and biomechanically. The most common injury related to longer time loss from participation is an anterior cruciate ligament rupture. Higher injury incidence is associated with a higher level of experience and competition. Orthopaedic management of martial arts injuries should reflect the specific needs of each martial artist and the biomechanics of motions common to each style. Full-contact practitioners may benefit from broader surgical indications and special attention to the choice and positioning of implants; nonsurgical treatment may be appropriate for certain pediatric or noncontact practitioners. Approximately 60% of martial artists can return to the preinjury level of participation after a major injury. Injury prevention and rehabilitation programs should optimize neuromotor control and core engagement to ensure proper body mechanics. Gradual incorporation of martial arts movement into the postoperative physical therapy curriculum can benefit physical progress and help gain confidence toward full participation.

Surgical Management of Traumatic Meniscus Injuries.

The menisci increase the contact area of load bearing in the knee and thus disperse the mechanical stress via their circumferential tensile fibers. Traumatic meniscus injuries cause mechanical symptoms in the knee, and are more prevalent amongst younger, more active patients, compared to degenerative tears amongst the elderly population. Traumatic meniscus tears typically result from the load-and-shear mechanism in the knee joint. The treatment depends on the size, location, and pattern of the tear. For non-repairable tears, partial or total meniscal resection decreases its tensile stress and increases joint contact stress, thus potentiating the risk of arthritis. A longitudinal vertical tear pattern at the peripheral third red-red zone leads to higher healing potential after repair. The postoperative rehabilitation protocols after repair range from immediate weight-bearing with no range of motion restrictions to non-weight bearing and delayed mobilization for weeks. Pediatric and adolescent patients may require special considerations due to their activity levels, or distinct pathologies such as a discoid meniscus. Further biomechanical and biologic evidence is needed to guide surgical management, postoperative rehabilitation protocols, and future technology applications for traumatic meniscus injuries.

Long-Term Outcomes at Skeletal Maturity of Combined Pelvic and Femoral Osteotomy for the Treatment of Legg-Calve-Perthes Disease.

Surgical treatment for Legg-Calve-Perthes disease (LCPD) is recommended for older children with moderate to severe disease. We sought to determine whether double osteotomies lead to improved radiologic outcomes compared to reported non-operative outcomes. Patients older than 6 years of age diagnosed with LCPD lateral pillar B or C who were treated with pelvic and femoral osteotomies were included. Radiologic outcomes and leg-length discrepancies were assessed using the Stulberg classification and were compared with the current literature. Fifteen hips in fourteen patients were treated with double osteotomy for LCPD, and seven had lateral pillar C disease (47%). The mean age at surgery was 8.6 years (range, 7.2-10.4) and the mean age at follow-up was 20.2 years (range, 14.2-35.6). At a mean 11.6-year follow-up (range: 6.3-25.2), double osteotomy resulted in 40% of patients having Stulberg I/II scores, 27% having Stulberg III scores, and 33% having Stulberg IV/V scores. The mean leg-length discrepancy was 1.4 cm in lateral pillar C patients compared to 0.8 cm in lateral pillar B patients. Four patients underwent additional surgeries, including two who required total hip arthroplasty. Double osteotomy as an alternative surgical procedure for the treatment of LCPD did not show improved outcomes when compared to historic non-operative cohorts.

The Cost and Educational Experience of Treating Supracondylar Humerus Fractures: A Pilot Analysis on Standardizing Surgical Care.

Closed reduction and percutaneous pinning (CRPP) for supracondylar humeral fractures (SCHF) comprised considerable surgical volume in pediatric orthopaedics. Limited reports are available on how standardization of the surgical care affects the cost and trainee's learning experience. Methods: Cost analysis was performed by chart review with the billing department in a university teaching hospital. The association of cost with perioperative variables was determined by univariate and multivariable analyses. The educational experience was acquired by questionnaires completed by seven attending surgeons and 22 orthopaedic trainees. Results: Fifty-one patients were included, revealing the hospital charge of $6,345 per CRPP case. Most of the cost comprised OR time (67%) and anesthesia time (13%). The attending surgeon and fracture type were independently associated with anesthesia time. Standardization of care was perceived for better learning experience and cost saving. Conclusion: Efforts in the standardization of SCHF surgical care can improve cost saving and trainees' learning experience.

Operative Versus Nonoperative Treatment of Acute Achilles Tendon Ruptures: A Pilot Economic Decision Analysis.

BACKGROUND: The operative treatment of Achilles tendon ruptures has been associated with lower rerupture rates and better function but also a risk of surgery-related complications compared with nonoperative treatment, which may provide improved outcomes with accelerated rehabilitation protocols. However, economic decision analyses integrating the updated costs of both treatment options are limited in the literature. PURPOSE: To compare the cost-effectiveness of operative and nonoperative treatment of acute Achilles tendon tears. STUDY DESIGN: Economic and decision analysis; Level of evidence, 2. METHODS: An economic decision model was built to assess the cost-utility ratio (CUR) of open primary repair versus nonoperative treatment for acute Achilles tendon ruptures, based on direct costs from the practices of sports medicine and foot and ankle surgeons at a single tertiary academic center, with published outcome probabilities and patient utility data. Multiway sensitivity analyses were performed to reflect the range of data. RESULTS: Nonoperative treatment was more cost-effective in the average scenario (nonoperative CUR, US$520; operative CUR, US$1995), but crossover occurred during the sensitivity analysis (nonoperative CUR range, US$224-US$2079; operative CUR range, US$789-US$8380). Operative treatment cost an extra average marginal CUR of US$1475 compared with nonoperative treatment, assuming uneventful healing in both treatment arms. The sensitivity analysis demonstrated a decreased marginal CUR of operative treatment when the outcome utility was maximized, and rerupture rates were minimized compared with nonoperative treatment. CONCLUSION: Nonoperative treatment was more cost-effective in average scenarios. Crossover indicated that open primary repair would be favorable for maximized outcome utility, such as that for young athletes or heavy laborers. The treatment decision for acute Achilles tendon ruptures should be individualized. These pilot results provide inferences for further longitudinal analyses incorporating future clinical evidence.

Medial Tibial Slope Determined by Plain Radiography Is Not Associated with Primary or Recurrent Anterior Cruciate Ligament Tears.

Increased tibial slope may be associated with anterior cruciate ligament (ACL) injuries, although potential confounding effects from various patient characteristics and radiographic quantification methods have not been rigorously studied. The association of the slope of the lateral plateau with recurrent ACL injury after primary ACL reconstruction has recently been reported, but the role of medial slope is less well defined. The purpose of this study was to (1) assess medial tibial slope measurement reliability among examiners, (2) compare medial tibial slope values between patients undergoing primary ACL reconstruction, reinjured patients undergoing revision ACL reconstruction, and a control cohort with an intact ACL, (3) analyze if the medial tibial slope is an independent risk factor for noncontact ACL injury, and (4) assess how different anatomical references affect medial tibial slope values. A total of 206 patients were enrolled into one of three groups: (1) ACL-intact controls (CONTROL, n = 83), (2) first-time ACL-injured patients (PRIMARY, n = 77), and (3) patients undergoing revision ACL reconstruction (REVISION, n = 46). Three fellowship-trained sports medicine surgeons performed repeated measurements of plain lateral radiographs. The medial tibial slope was determined by three anatomical references: anterior tibial cortex (anterior tibial slope [ATS]), posterior tibial cortex (posterior tibial slope [PTS]), and the anatomical long axis of the tibia (composite tibial slope [CTS]). Substantial intra- and interobserver reliabilities were established by the intraclass correlation coefficient of 0.73 to 0.89. There was no difference in CTS, ATS, or PTS comparing the CONTROL, PRIMARY, and REVISION groups upon univariate analyses. Multivariable logistic regression model showed that none of the slope values was independently associated with ACL injury. The mean ATS for all 206 subjects was 4 and 8 degrees greater than the mean CTS and PTS, respectively. ATS correlated only moderately to PTS. We concluded that medial tibial slope measured on radiographs is not associated with primary or recurrent ACL injury, and has substantial variation and suboptimal correlation when using different anatomical references despite good inter- and intraobserver reliabilities.

Low-Dose Computed Tomography Reduces Radiation Exposure by 90% Compared With Traditional Computed Tomography Among Patients Undergoing Hip-Preservation Surgery.

PURPOSE: To compare the delivered radiation dose between a low-dose hip computed tomography (CT) scan protocol and traditional hip CT scan protocols (i.e., "traditional CT"). METHODS: This was a retrospective comparative cohort study. Patients who underwent hip-preservation surgery (including arthroscopy, surgical hip dislocation, or periacetabular osteotomy procedures) at our institution between 2016 and 2017 were identified. Patients were excluded if they had a body mass index (BMI) greater than 35, they underwent previous surgery, or a radiation dose report was absent. The low-dose group included patients who underwent hip CT at our institution using a standardized protocol of 100 kV (peak), 100 milliampere-seconds (mAs), and a limited scanning field. The traditional CT group included patients who had hip CT scans performed at outside institutions. The total effective dose (Ehip), effective dose per millimeter of body length scanned, patients' age, and patients' BMI were compared by univariate analysis. The correlation of Ehip to BMI was assessed. RESULTS: The study included 41 consecutive patients in the low-dose group and 18 consecutive patients in the traditional CT group. Low-dose CT resulted in a 90% reduction in radiation exposure compared with traditional CT (Ehip, 0.97 ± 0.28 mSv vs 9.68 ± 6.67 mSv; P < .0001). Age (28 ± 11 years vs 26 ± 10 years, P = .42), sex (83% female patients vs 76% female patients, P = .74), and BMI (24 ± 3 vs 24 ± 3, P = .75) were not different between the 2 groups. Ehip had a poor but significant correlation to BMI in the low-dose CT group (R2 = 0.14, slope = 0.03, P = .02) and did not correlate to BMI in the traditional CT group (R2 = 0.13, P = .14). CONCLUSIONS: A low-dose hip CT protocol for the purpose of hip-preservation surgical planning resulted in a 90% reduction in radiation exposure compared with traditional CT. LEVEL OF EVIDENCE: Level II, diagnostic study.

Distal Junctional Failure Following Pediatric Spinal Fusion.

BACKGROUND: Adjacent segment pathology is a known complication after spinal fusion, but little has been reported on junctional failure. A series of adolescent patients presented with acute distal junctional failure (DJF). We sought to determine any common features of these patients to develop a prevention strategy. METHODS: A retrospective review was conducted of pediatric patients who developed DJF after instrumented spinal fusion performed at 2 institutions from 1999 to 2013. Patients with proximal junctional failure or junctional kyphosis without failure were excluded. RESULTS: Fifteen subjects were identified with mean follow-up of 38 months. Distal failure occurred a mean of 60 days after index surgery, with history of minor trauma in 4 patients. Failures included 3-column Chance fracture (11) or instrumentation failure (4). Thirteen patients presented with back pain and/or acute kyphosis, whereas 2 asymptomatic patients presented with healed fractures. Two patients also developed new onset of severe lower extremity neurological deficit after fracture, which improved but never resolved after revision. A total of 13/15 subjects required revision surgery, typically within 1 week. Complications associated with revision surgery were encountered in 8 patients (62%). Major complications that required return to the operating room included 2 deep infections, 2 instrumentation failures, and dense lower extremity paralysis that improved after medial screw revision and decompression. At final follow-up, 10 patients are asymptomatic, 2 have persistent neurological deficit, 2 have chronic pain, and 1 has altered gait with gait aid requirement. CONCLUSIONS: This study analyzes a heterogenous cohort of spinal fusion patients who developed DJF from 3-column Chance fracture or instrumentation failure. Revision surgery is typically required, but has a high complication rate and can result in severe neurological deficit, highlighting the morbidity of this complication. It is unclear whether level of the lowest instrumented vertebra contributes to DJF. Increased awareness of junctional failure in children may prompt additional studies to further characterize risk factors and preventative strategies. LEVEL OF EVIDENCE: Level IV-study-type case series.

Association of the Graft Size and Arthrofibrosis in Young Patients After Primary Anterior Cruciate Ligament Reconstruction.

INTRODUCTION: This study investigated the association of graft-related surgical factors and patient characteristics with the odds of arthrofibrosis after primary anterior cruciate ligament reconstruction (ACL-R). METHODS: A retrospective case-control study assessed consecutive patients who underwent primary ACL-R in one tertiary pediatric hospital. Each arthrofibrosis case was matched to three controls for sex, calendar year, and age at the time of ACL-R, as well as the primary surgeon. Conditional multivariable logistic regression assessed the independent association of graft diameter, time from injury to ACL-R, concomitant knee pathologies, and body mass index. RESULTS: Twenty arthrofibrosis cases of 1,121 ACL-R patients (incidence 1.8%) were matched to 60 controls resulting in the mean age of 14.5 years. An increase of 1 mm graft diameter was associated with 3.2-times increased odds of arthrofibrosis. Other variables were not independently associated with arthrofibrosis. CONCLUSION: For young patients, the decision on the graft size must consider the possibility of arthrofibrosis with a larger graft versus reinjury with a smaller graft.

Biomechanics of osteochondral impact with cushioning and graft Insertion: Cartilage damage is correlated with delivered energy.

Articular cartilage is susceptible to impact injury. Impact may occur during events ranging from trauma to surgical insertion of an OsteoChondral Graft (OCG) into an OsteoChondral Recipient site (OCR). To evaluate energy density as a mediator of cartilage damage, a specialized drop tower apparatus was used to impact adult bovine samples while measuring contact force, cartilage surface displacement, and OCG advancement. When a single impact was applied to an isolated (non-inserted) OCG, force and surface displacement each rose monotonically and then declined. In each of five sequential impacts of increasing magnitude, applied to insert an OCG into an OCR, force rose rapidly to an initial peak, with minimal OCG advancement, and then to a second prolonged peak, with distinctive oscillations. Energy delivered to cartilage was confirmed to be higher with larger drop height and mass, and found to be lower with an interposed cushion or OCG insertion into an OCR. For both single and multiple impacts, the total energy density delivered to the articular cartilage correlated to damage, quantified as total crack length. The corresponding fracture toughness of the articular cartilage was 12.0 mJ/mm2. Thus, the biomechanics of OCG insertion exhibits distinctive features compared to OCG impact without insertion, with energy delivery to the articular cartilage being a factor highly correlated with damage.

Spike densities of the amygdala and neocortex reflect progression of kindled motor seizures.

Amygdala kindling is a common temporal lobe-like seizure model. In the present study, temporal and spectral analyses of the ictal period were investigated throughout amygdala kindling in response to different behavioral seizures. Right-side amygdala was kindled to induce epileptiform afterdischarges (ADs). ADs of both the frontal cortex and amygdala were analyzed. Powers of the low (0-9 Hz)- and high (12-30 Hz)-frequency bands in response to different behavioral seizures were calculated. Densities of upward and downward peaks of spikes, which reflected information of spike count and spike pattern, throughout kindle-induced ADs were calculated. Progression was seen in the temporal and spectral characteristics of amygdala-kindled ADs in response to behaviors. Numbers of significant differences of all 1-s AD segments between two Racine's seizure stages were significantly higher in upward and downward indexes of the temporal spike than those using the spectral method in both the amygdala and neocortex. Ability for distinguishing seizure stages was significantly higher in temporal spike density of amygdala ADs compared to those of frontal ADs. Our results showed that amygdala kindling caused spectrotemporal changes of activities in the amygdala and frontal cortex. The density of spike-related peaks had better distinguishability in response to behavioral seizures, particularly in a seizure zone of amygdala. The present study provides a new temporal index of spike's peak density to understand progression of motor seizures in the kindling process.

Impact insertion of osteochondral grafts: Interference fit and central graft reduction affect biomechanics and cartilage damage.

An osteochondral graft (OCG) is an effective treatment for articular cartilage and osteochondral defects. Impact of an OCG during insertion into the osteochondral recipient site (OCR) can cause chondrocyte death and matrix damage. The aim of the present study was to analyze the effects of graft-host interference fit and a modified OCG geometry on OCG insertion biomechanics and cartilage damage. The effects of interference fit (radius of OCG - radius of OCR), loose (0.00 mm), moderate (0.05 mm), tight (0.10 mm), and of a tight fit with OCG geometry modification (central region of decreased radius), were analyzed for OCG cylinders and OCR blocks from adult bovine knee joints with an instrumented drop tower apparatus. An increasingly tight (OCG - OCR) interference fit led to increased taps for insertion, peak axial force, graft cartilage axial compression, cumulative and total energy delivery to cartilage, lower time of peak axial force, lesser graft advancement during each tap, higher total crack length in the cartilage surface, and lower chondrocyte viability. The modified OCG, with reduction of diameter in the central area, altered the biomechanical insertion variables and biological consequences to be similar to those of the moderate interference fit scenario. Micro-computed tomography confirmed structural interference between the OCR bone and both the proximal and distal bone segments of the OCGs, with the central regions being slightly separated for the modified OCGs. These results clarify OCG insertion biomechanics and mechanobiology, and introduce a simple modification of OCGs that facilitates insertion with reduced energy while maintaining a structural interference fit. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:377-386, 2018.

How Does Patient Radiation Exposure Compare With Low-dose O-arm Versus Fluoroscopy for Pedicle Screw Placement in Idiopathic Scoliosis?

BACKGROUND: Intraoperative C-arm fluoroscopy and low-dose O-arm are both reasonable means to assist in screw placement for idiopathic scoliosis surgery. Both using pediatric low-dose O-arm settings and minimizing the number of radiographs during C-arm fluoroscopy guidance decrease patient radiation exposure and its deleterious biological effect that may be associated with cancer risk. We hypothesized that the radiation dose for C-arm-guided fluoroscopy is no less than low-dose O-arm scanning for placement of pedicle screws. METHODS: A multicenter matched-control cohort study of 28 patients in total was conducted. Fourteen patients who underwent O-arm-guided pedicle screw insertion for spinal fusion surgery in 1 institution were matched to another 14 patients who underwent C-arm fluoroscopy guidance in the other institution in terms of the age of surgery, body weight, and number of imaged spine levels. The total effective dose was compared. A low-dose pediatric protocol was used for all O-arm scans with an effective dose of 0.65 mSv per scan. The effective dose of C-arm fluoroscopy was determined using anthropomorphic phantoms that represented the thoracic and lumbar spine in anteroposterior and lateral views, respectively. The clinical outcome and complications of all patients were documented. RESULTS: The mean total effective dose for the O-arm group was approximately 4 times higher than that of the C-arm group (P<0.0001). The effective dose for the C-arm patients had high variability based on fluoroscopy time and did not correlate with the number of imaged spine levels or body weight. The effective dose of 1 low-dose pediatric O-arm scan approximated 85 seconds of the C-arm fluoroscopy time. All patients had satisfactory clinical outcomes without major complications that required returning to the operating room. CONCLUSIONS: Radiation exposure required for O-arm scans can be higher than that required for C-arm fluoroscopy, but it depends on fluoroscopy time. Inclusion of more medical centers and surgeons will better account for the variability of C-arm dose due to distinct patient characteristics, surgeon's preference, and individual institution's protocol. LEVEL OF EVIDENCE: Level III-case-control study.

Perioperative Vision Loss in Spine Surgery and Other Orthopaedic Procedures.

Perioperative vision loss is a rare complication of orthopaedic surgery and has been documented after spine, knee, hip, and shoulder procedures. It is associated with several ophthalmologic diagnoses, most commonly ischemic optic neuropathy. Although the pathophysiology remains unclear, current evidence suggests that systemic hemodynamic compromise and altered balance of intraocular perfusion contribute to the development of ischemic optic neuropathy. Although vision recovery has been reported, the prognosis of perioperative vision loss is poor, and no proven effective treatment is available. Perioperative vision loss is unpredictable and can occur in healthy patients. Associated risk factors include pediatric or elderly age, male sex, obesity, anemia, hypotension or hypertension, perioperative blood loss, prolonged surgical time, and prone positioning. Preventive strategies include avoiding direct pressure to the eye, elevating the head, optimizing perioperative hemodynamic status, and minimizing surgical time with staged surgical procedures as appropriate.

Risk Factors for 30-Day Unplanned Readmission and Major Perioperative Complications After Spine Fusion Surgery in Adults: A Review of the National Surgical Quality Improvement Program Database.

STUDY DESIGN: Retrospective review of a prospective cohort. OBJECTIVE: The aim of the study was to determine the patient characteristics and surgical procedure factors related to increased rates of 30-day unplanned readmission and major perioperative complications after spinal fusion surgery, and the association between unplanned readmission and major complications. SUMMARY OF BACKGROUND DATA: Reducing unplanned readmissions can reduce the cost of healthcare. Payers are implementing penalties for 30-day readmissions after discharge. There is limited data regarding the current rates and risk factors for unplanned readmission and major complications related to spinal fusion surgery. METHODS: Spine fusion patients were identified using the 2012 and 2013 American College of Surgeons National Surgical Quality Improvement Program Participant User File. Rates of readmissions within 30 days after spine fusion surgery were calculated using the person-years method. Cox proportional hazards models were used to assess the independent associations of spine surgical procedure types, diagnoses, patient profiles, and major perioperative complications with unplanned related readmissions. Independent risk factors for major complications were assessed by multivariable logistic regression. RESULTS: Of the 18,602 identified patients, there was a 5.2% overall major perioperative complication rate. There was a rate of 4.4% per 30 person-days for unplanned readmissions related to index surgery. Independent risk factors for both readmissions and major perioperative complications included combined anterior and posterior surgery, diagnosis of solitary tumor, older age, and higher American Society of Anesthesiologists class. Patients with deep/organ surgical site infection carried higher risk of having unplanned readmission, followed by pulmonary embolism, acute renal failure, and stroke/cerebral vascular accident with neurological deficit. CONCLUSION: This study provides benchmark rates of 30-day readmission based on diagnosis and procedure codes from a high-quality database for adult spinal fusion patients and showed increased rates of 30-day unplanned readmission and major perioperative complications for patients with specific risk factors. Targeted preoperative planning on modifiable risk factors with proportional reimbursement may promote higher-quality healthcare. LEVEL OF EVIDENCE: 3.

Addition of Mesenchymal Stem Cells to Autologous Platelet-Enhanced Fibrin Scaffolds in Chondral Defects: Does It Enhance Repair?

BACKGROUND: The chondrogenic potential of culture-expanded bone-marrow-derived mesenchymal stem cells (BMDMSCs) is well described. Numerous studies have also shown enhanced repair when BMDMSCs, scaffolds, and growth factors are placed into chondral defects. Platelets provide a rich milieu of growth factors and, along with fibrin, are readily available for clinical use. The objective of this study was to determine if the addition of BMDMSCs to an autologous platelet-enriched fibrin (APEF) scaffold enhances chondral repair compared with APEF alone. METHODS: A 15-mm-diameter full-thickness chondral defect was created on the lateral trochlear ridge of both stifle joints of twelve adult horses. In each animal, one defect was randomly assigned to receive APEF+BMDMSCs and the contralateral defect received APEF alone. Repair tissues were evaluated one year later with arthroscopy, histological examination, magnetic resonance imaging (MRI), micro-computed tomography (micro-CT), and biomechanical testing. RESULTS: The arthroscopic findings, MRI T2 map, histological scores, structural stiffness, and material stiffness were similar (p > 0.05) between the APEF and APEF+BMDMSC-treated repairs at one year. Ectopic bone was observed within the repair tissue in four of twelve APEF+BMDMSC-treated defects. Defects repaired with APEF alone had less trabecular bone edema (as seen on MRI) compared with defects repaired with APEF+BMDMSCs. Micro-CT analysis showed thinner repair tissue in defects repaired with APEF+BMDMSCs than in those treated with APEF alone (p < 0.05). CONCLUSIONS: APEF alone resulted in thicker repair tissue than was seen with APEF+BMDMSCs. The addition of BMDMSCs to APEF did not enhance cartilage repair and stimulated bone formation in some cartilage defects. CLINICAL RELEVANCE: APEF supported repair of critical-size full-thickness chondral defects in horses, which was not improved by the addition of BMDMSCs. This work supports further investigation to determine whether APEF enhances cartilage repair in humans.

Switching to a Pediatric Dose O-Arm Protocol in Spine Surgery Significantly Reduced Patient Radiation Exposure.

BACKGROUND: Intraoperative computed tomography and image-guided navigation improve the accuracy of screw placement. Radiation exposure to the patient remains a primary drawback. The objective of the present study was to compare the total intraoperative radiation dose and assess the resultant image quality for O-arm-assisted pedicle screw insertion, among 3 protocols: default (manufacturer recommended), institutional (reduced dose utilized in our institution), and pediatric (new protocol with lowest dose). METHODS: Thirty-seven consecutive patients under the age of 18 years underwent posterior instrumentation of the spine and underwent an intraoperative O-arm scan. Techniques (kV and mAs) for default and institutional dose settings were manually adjusted based on spinal level and body weight. Pediatric dose techniques were 80 kV/80 mAs with no adjustment for level or weight. The number of scans repeated because of inadequate imaging was assessed, and the mean estimated effective dose between the 3 protocols was compared. RESULTS: Sixty-eight scans were performed in 37 consecutive patients with mean age of 14 years and mean weight of 55 kg. For reference, the effective radiation dose of a chest x-ray is approximately 0.10 mSv. Use of the default protocol resulted in higher mean effective dose per scan of 4.65 mSv, whereas institutional protocol resulted in 2.37 mSv. The pediatric protocol reduced the mean dose to 0.65 mSv. The total effective dose per surgery was: 1.17 mSv (pediatric), 3.83 mSv (institutional), and 12.79 mSv (default) (P<0.0001 each). All scans lead to satisfactory image quality except in 1 patient >100 kg with stainless steel implants. There were no neurological or other implant-related complications. The pediatric protocol resulted in satisfactory image quality with the lowest total radiation dose, only 1/10 of that of the default protocol. CONCLUSIONS: We successfully switched to a pediatric low-dose O-arm protocol in clinical practice, reducing the dose to <1/4 of the mean annual natural background radiation. This may allow use of intraoperative computed tomography and navigation for pedicle screw placement without excessive radiation exposure to young patients. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Pediatric Ankle Fractures: Concepts and Treatment Principles.

Current clinical concepts are reviewed regarding the epidemiology, anatomy, evaluation, and treatment of pediatric ankle fractures. Correct diagnosis and management relies on appropriate examination, imaging, and knowledge of fracture patterns specific to children. Treatment is guided by patient history, physical examination, plain film radiographs and, in some instances, computed tomography. Treatment goals are to restore acceptable limb alignment, physeal anatomy, and joint congruency. For high-risk physeal fractures, patients should be monitored for growth disturbance as needed until skeletal maturity.

Magnetic Expansion Control System Achieves Cost Savings Compared to Traditional Growth Rods: An Economic Analysis Model.

STUDY DESIGN: Medical economic model with multi-way sensitivity analysis. OBJECTIVE: To compare the direct costs of growing rod (GR) versus Magnetic Expansion Control System (MG) from a payer's perspective. We hypothesized that over time the MG will become more cost-effective. SUMMARY OF BACKGROUND DATA: Traditional GRs provide effective treatment, but require periodic lengthening surgery. MG allows rod lengthening in clinic, but the implant is expensive. The cumulative cost savings are not well understood. METHODS: Index surgery, implant cost, lengthening procedure, and revision surgery due to implant failure or infection were identified as major parameters contributing to the cumulative cost. The "base," "low," and "high" values for the cost and the incidence of each parameter were determined by literature reports, health care database search, or expert consultation. The cumulative cost was compared annually during 5 years of follow-up. Marginal cost was defined as the cost of (GR-MG) for each cumulative year. Final cumulative cost and extreme case scenario at year 5 were assessed by deterministic sensitivity analysis. RESULTS: MG resulted in higher cumulative cost at years 1 and 2, and became lower cost at years 3 through 5. The marginal cost at year 1 was a negative value of $16K, and trended toward positive values of $12K at year 3 and $40K by year 5. Sensitivity analysis revealed that in extreme case, MG could cost more, shown by a marginal cost of $26K by implementing the extreme values of the 3 parameters carrying highest variance: MG-infection management, GR-revision surgery, and GR-lengthening procedure. CONCLUSION: MG achieved cost neutrality to GR at 3 years after index surgery. This is the first medical economic study in the United States comparing the cost of GR versus MG and demonstrates potential cost-effectiveness of MG from payer's perspective if in place for more than 3 years. LEVEL OF EVIDENCE: 2.