Exome sequencing of 1190 non-syndromic clubfoot cases reveals HOXD12 as a novel disease gene.

BACKGROUND: Clubfoot, presenting as a rigid inward and downward turning of the foot, is one of the most common congenital musculoskeletal anomalies. The aetiology of clubfoot is poorly understood and variants in known clubfoot disease genes account for only a small portion of the heritability. METHODS: Exome sequence data were generated from 1190 non-syndromic clubfoot cases and their family members from multiple ethnicities. Ultra-rare variant burden analysis was performed comparing 857 unrelated clubfoot cases with European ancestry with two independent ethnicity-matched control groups (1043 in-house and 56 885 gnomAD controls). Additional variants in prioritised genes were identified in a larger cohort, including probands with non-European ancestry. Segregation analysis was performed in multiplex families when available. RESULTS: Rare variants in 29 genes were enriched in clubfoot cases, including PITX1 (a known clubfoot disease gene), HOXD12, COL12A1, COL9A3 and LMX1B. In addition, rare variants in posterior HOX genes (HOX9-13) were enriched overall in clubfoot cases. In total, variants in these genes were present in 8.4% (100/1190) of clubfoot cases with both European and non-European ancestry. Among these, 3 are de novo and 22 show variable penetrance, including 4 HOXD12 variants that segregate with clubfoot. CONCLUSION: We report HOXD12 as a novel clubfoot disease gene and demonstrate a phenotypic expansion of known disease genes (myopathy gene COL12A1, Ehlers-Danlos syndrome gene COL9A3 and nail-patella syndrome gene LMX1B) to include isolated clubfoot.

Eye of the Carpenter: How Well do Orthopaedic Surgeons Estimate Angular Measurements in Derotational Osteotomies?

BACKGROUND: Femoral derotational osteotomies are used by orthopaedic surgeons to decrease version in a variety of pathologies. Intraoperatively, the goal of the surgery is to decrease the rotation of the femur to within physiological range. Surgeons generally visually estimate the angle of correction based on bone markers at the rotating cylindrical portion of the femur. This study sought first to assess the accuracy and inter-rater reliability of surgeons with respect to angle creation, and then to implement a training intervention. METHODS: A rotational femur model was constructed and tested among surgeons and nonsurgeons. Surgeons were then randomized into an experimental and control cohort with training on the model as the intervention. Subjects were asked to create target angles of 15, 30, 45, and 60 degrees using only Kirschner wires and then only bone marks for reference. Independent and paired t -tests were performed to determine variability between cohorts. RESULTS: The mean angle creation error and range of the surgeon cohort were significantly lower than those of the nonsurgeon cohort. Within the nonsurgeon cohort, the mean angle creation error and range of the wire modality were significantly lower than that of the mark modality. The mean angle creation error and range of the trained cohort were significantly lower than the untrained cohort. CONCLUSIONS: The considerable inter-subject range within the surgeon cohort highlights a need for the reinforcement of basic geometric principles within orthopaedic instruction. This model allows for immediate, accurate feedback on angle creation, and training appears to be both time and cost-effective. The physiological range allows for a level of variability between surgical outcomes without consequence. However, the more than 20 degree range determined by this study does not fall within those bounds and should be addressed. CLINICAL RELEVANCE: Moving forward, rotational estimation as a surgical skill should increase in prominence within orthopaedic instruction to maximize future joint health, and additional emphasis should be placed on fundamental spatial orientation during training.

Distal chromosome 16p11.2 duplications containing SH2B1 in patients with scoliosis.

INTRODUCTION: Adolescent idiopathic scoliosis (AIS) is a common musculoskeletal disorder with strong evidence for a genetic contribution. CNVs play an important role in congenital scoliosis, but their role in idiopathic scoliosis has been largely unexplored. METHODS: Exome sequence data from 1197 AIS cases and 1664 in-house controls was analysed using coverage data to identify rare CNVs. CNV calls were filtered to include only highly confident CNVs with >10 average reads per region and mean log-ratio of coverage consistent with single-copy duplication or deletion. The frequency of 55 common recurrent CNVs was determined and correlated with clinical characteristics. RESULTS: Distal chromosome 16p11.2 microduplications containing the gene SH2B1 were found in 0.7% of AIS cases (8/1197). We replicated this finding in two additional AIS cohorts (8/1097 and 2/433), resulting in 0.7% (18/2727) of all AIS cases harbouring a chromosome 16p11.2 microduplication, compared with 0.06% of local controls (1/1664) and 0.04% of published controls (8/19584) (p=2.28×10-11, OR=16.15). Furthermore, examination of electronic health records of 92 455 patients from the Geisinger health system showed scoliosis in 30% (20/66) patients with chromosome 16p11.2 microduplications containing SH2B1 compared with 7.6% (10/132) of controls (p=5.6×10-4, OR=3.9). CONCLUSIONS: Recurrent distal chromosome 16p11.2 duplications explain nearly 1% of AIS. Distal chromosome 16p11.2 duplications may contribute to scoliosis pathogenesis by directly impairing growth or by altering expression of nearby genes, such as TBX6. Individuals with distal chromosome 16p11.2 microduplications should be screened for scoliosis to facilitate early treatment.

Teaching the Basics: Development and Validation of a Distal Radius Reduction and Casting Model.

BACKGROUND: Approximately one-third of reduced pediatric distal radius fractures redisplace, resulting in further treatment. Two major modifiable risk factors for loss of reduction are reduction adequacy and cast quality. Closed reduction and immobilization of distal radius fractures is an Accreditation Council for Graduate Medical Education residency milestone. Teaching and assessing competency could be improved with a life-like simulation training tool. QUESTIONS/PURPOSES: Our goal was to develop and validate a realistic distal radius fracture reduction and casting simulator as determined by (1) a questionnaire regarding the "realism" of the model and (2) the quantitative assessments of reduction time, residual angulation, and displacement. METHODS: A distal radius fracture model was created with radiopaque bony segments and articulating elbows and shoulders. Simulated periosteum and internal deforming forces required proper reduction and casting techniques to achieve and maintain reduction. The forces required were estimated through an iterative process through feedback from experienced clinicians. Embedded monofilaments allowed for quantitative assessment of residual displacement and angulation through the use of fluoroscopy. Subjects were asked to perform closed reduction and apply a long arm fiberglass cast. Primary performance variables assessed included reduction time, residual angulation, and displacement. Secondary performance variables consisted of number of fluoroscopic images, casting time, and cast index (defined as the ratio of the internal width of the forearm cast in the sagittal plane to the internal width in the coronal plane at the fracture site). Subject grading was performed by two blinded reviewers. Interrater reliability was nearly perfect across all measurements (intraclass correlation coefficient range, 0.94-0.99), thus disagreements in measurements were handled by averaging the assessed values. After completion the participants answered a Likert-based questionnaire regarding the realism of simulation. Eighteen participants consented to participate in the study (eight attending pediatric orthopaedic surgeons, six junior residents, four senior residents). The performances of junior residents (Postgraduate Year [PGY] 1-2), senior residents (PGY 3-5), and attending surgeons were compared using one-way ANOVA with Tukey's-adjusted pairwise comparisons. RESULTS: The majority of participants (15 of 18) felt that the model looked, felt, and moved like a human forearm. All participants strongly agreed that the model taught the basic steps of fracture reduction and should be implemented in orthopaedic training. Attending surgeons reduced fractures in less time than junior residents (60 ± 27 seconds versus 460 ± 62 seconds; mean difference, 400 seconds; 95% CI, 335-465 seconds; p < 0.001). Residual angulation was greater for junior residents when compared with attending surgeons on AP (7° ± 5° versus 0.7° ± 0.9°; mean difference, 6.3°; 95% CI, 3°-11°; p = 0.003) and lateral (27° ± 7° versus 7° ± 5°; mean difference, 20°; 95% CI, 13°-27°; p = 0.001) radiographs. Similarly, residual displacement was greater for junior residents than either senior residents (mean difference, 16 mm; 95% CI, 2-34 mm; p = 0.05) or attending surgeons (mean difference, 15 mm; 95% CI, 3-27 mm; p = 0.02) on lateral images. There were no differences identified in secondary performance variables (number of fluoroscopic images, casting time, and cast index) between groups. CONCLUSIONS: This is the first distal radius fracture reduction model to incorporate an elbow and shoulder and allow quantitative assessment of the fracture reduction. This simulator may be useful in an orthopaedic resident training program to help them reach a defined minimum level of competency. This simulator also could easily be integrated in other accreditation and training programs, including emergency medicine. LEVEL OF EVIDENCE: Level II, therapeutic study.

Utility of Postoperative Antibiotics After Percutaneous Pinning of Pediatric Supracondylar Humerus Fractures.

BACKGROUND: Pediatric supracondylar humerus fractures are common injuries that are often treated surgically with closed reduction and percutaneous pinning. Although surgical-site infections are rare, postoperative antibiotics are frequently administered without evidence or guidelines for their use. With the increasing prevalence of antibiotic-resistant organisms and heightened focus on health care costs, appropriate and evidence-based use of antibiotics is needed. We hypothesized that postoperative antibiotic administration would not decrease the rate of surgical-site infection. METHODS: A billing query identified 951 patients with operatively treated supracondylar humerus fractures at our institution over a 15-year period. Records were reviewed for demographic data, perioperative antibiotic use, and the presence of surgical-site infection. Exclusion criteria were open fractures, open reduction, pathologic fractures, metabolic bone disease, the presence of other injuries that required operative treatment, and follow-up <2 weeks after pin removal. χ and Fisher exact test were used to compare antibiotic use to the incidence of surgical-site infection. RESULTS: Six hundred eighteen patients met our inclusion criteria. Two hundred thirty-eight patients (38.5%) received postoperative antibiotics. Eleven surgical-site infections were identified for an overall rate of 1.8%. The use of postoperative antibiotics was not associated with a lower rate of surgical-site infection (P=0.883). Patients with a type III fracture (P<0.001), diminished preoperative vascular (P=0.001) and neurological status (P=0.019), and postoperative hospital admission (P<0.001) were significantly more likely to receive postoperative antibiotics. CONCLUSIONS: Administration of postoperative antibiotics after closed reduction and percutaneous pinning of pediatric supracondylar humerus fractures does not decrease the rate of surgical-site infection. LEVEL OF EVIDENCE: Level III-therapeutic.

Pediatric Lyme Arthritis of the Hip: The Great Imitator?

BACKGROUND: Lyme arthritis (LA) of the hip can present similarly to septic arthritis (SA) and transient synovitis (TS). The primary purpose of this study was to determine clinical and laboratory parameters differentiating LA of the hip from SA or TS among children who had undergone hip aspiration during the evaluation of hip pain. METHODS: This was a retrospective review of all patients who underwent hip aspiration for the evaluation of hip pain at a tertiary care children's hospital in a Lyme endemic area. Clinical and laboratory data were reviewed and comparative analyses were performed between those diagnosed with LA, SA, and TS. Independent samples t test, ANOVA, and χ test were used to compare clinical and laboratory variables as appropriate. Multivariable logistic regression was used to elucidate independent predictors of LA. Statistical significance was set at P<0.05. RESULTS: Ninety-three hip aspirations (93 patients) were included in the final analysis. Seventeen patients were diagnosed with LA, 40 with SA, and 36 with TS. Multivariable logistic regression revealed febrile history (OR=16.3; 95% CI, 2.35-113.0) and increased peripheral white blood cell (WBC) count (OR=1.26; 95% CI, 1.01-1.58) to be significantly associated with increased odds of being diagnosed with SA versus LA. Increased erythrocyte sedimentation rate (ESR) was significantly associated with increased odds of being diagnosed with LA versus TS (OR=1.06; 95% CI, 1.02-1.10), whereas febrile history (OR=0.06; 95% CI, 0.01-0.49) and increased peripheral WBC count (OR=0.8; 95% CI, 0.65-0.98) were associated with decreased odds of LA. CONCLUSIONS: Children presenting in a Lyme endemic area with an isolated hip effusion are more likely to have LA versus SA if they have no history of fever and a decreased peripheral WBC count. Compared with TS, patients with LA are more likely to have an elevated ESR. This study adds to existing knowledge because there are few investigations examining isolated LA of the hip. LEVEL OF EVIDENCE: Level III-retrospective case-control study.

Does Perfusion MRI After Closed Reduction of Developmental Dysplasia of the Hip Reduce the Incidence of Avascular Necrosis?

BACKGROUND: Gadolinium-enhanced perfusion MRI (pMRI) after closed reduction/spica casting for developmental dysplasia of the hip (DDH) has been suggested as a potential means to identify and avoid avascular necrosis (AVN). To date, however, no study has evaluated the effectiveness of pMRI in clinical practice or compared it with other approaches (such as postreduction CT scan) to show a difference in the proportion of AVN. QUESTIONS/PURPOSES: (1) Can a pMRI-based protocol be used immediately post closed reduction to minimize the risk that AVN would develop? (2) What are the overall hip-related outcomes after closed reduction/spica casting using this protocol? (3) Do any patient-specific factors at the time of closed reduction predict future AVN? METHODS: This was a retrospective cohort study at a large tertiary care children's hospital. Between 2009 and 2013 we treated 43 patients with closed reduction/spica casting for DDH, of whom 33 (77%) received a postreduction pMRI. All patients were indicated for pMRI per treating surgeon preference. A convenience sample totaling 25 hips in 22 patients treated with pMRI was then established using the following exclusion criteria: DDH of neuromuscular/syndromic origin, failed initial closed reduction, less than 1 year of clinical and radiographic followup, and subsequent open reduction. Next, the 40 patients treated with closed reduction between 2004 and 2009 were screened until the chronologically most recent 25 hips (after applying the previously mentioned exclusion criteria) were identified in 21 of the first 34 patients (62%) screened. Although termed the CT group, specific postreduction imaging was not a defined inclusion criterion in this group with the majority (21 of 25 [84%]) receiving postreduction CT and the remainder (four of 25 [16%]) receiving only postreduction radiographs. All hips with globally decreased femoral head perfusion on postreduction pMRI were treated with immediate cast removal followed by repeat closed reduction or open reduction, as per surgeon preference, with two of 33 (6%) requiring such further interventions. Salter criteria were then used to determine the proportion of AVN on radiographs at 1-year and final followup. Secondary outcomes including residual dysplasia and the need for further corrective surgery were ascertained through radiographic and retrospective chart review. RESULTS: At 1-year followup there was no difference in the proportion of AVN in the historical CT group as compared with the pMRI group (six of 25 [24%] versus one of 25 [4%]; odds ratio [OR], 7.6; 95% confidence interval [CI], 0.8-363; p = 0.098). However, by final followup there was a statistically higher proportion of AVN in the CT group (seven of 25 [28%] versus one of 25 [4%]; OR, 9.3; 95% CI, 1.0-438; p = 0.049). No patient with normal perfusion on postreduction pMRI went on to develop AVN. In those pMRI patients in whom a successful reduction was initially obtained, two of 25 (8%) went on to require further corrective surgery and one of 25 (4%) had a redislocation event. With the numbers available, no patient-specific factors at the time of closed reduction were predictive of future AVN, including the patient's age/weight, the presence of an ossific nucleus, history of previous bracing treatment, or the abduction angle in spica cast. CONCLUSIONS: A pMRI-based protocol immediately after closed reduction/spica casting may decrease the risk of AVN by helping the surgeon to evaluate femoral head vascularity. Although preliminary in nature, this study could serve to guide further investigation into the potential role of pMRI for the treatment of patients who require closed reduction/spica casting for DDH. LEVEL OF EVIDENCE: Level III, therapeutic study.

Medial Epicondyle Fractures in Children and Adolescents: Shifting Care from General Hospitals to Children's Hospitals?

OBJECTIVES: To determine if there is a shift in the treatment of children with medial epicondyle fractures toward children's hospitals, and to explore potential confounders of any observed effect. STUDY DESIGN: The Healthcare Cost and Utilization Project Kids' Inpatient Database was used to examine the epidemiology of medial epicondyle fractures, particularly with attention to whether they were admitted to a general hospital or a children's hospital (defined as free-standing children's hospitals, specialty children's hospitals, and children's units within general hospitals). Age and insurance payer status were also collected and evaluated as potential confounders. RESULTS: The proportion of medial epicondyle hospital discharges from children's hospitals increased (from 29%-46%; P < .001), and the proportion of discharges from general hospitals declined over the study period (from 71%-42%; P < .001). Age and insurance payer status both remained consistent throughout the study period and did not contribute to this finding. CONCLUSIONS: This study demonstrates an increase in the proportion of discharges for pediatric medial epicondyle fractures from children's hospitals. Although this finding is likely multifactorial, it may represent increasing subspecialization and increasing medical liability when treating children. Children's hospitals should identify those conditions which will continue to increase in number and consider constructing clinical pathways in order to optimize delivery of care and resource utilization.

Effects of static exercises on hip muscle fatigue and knee wobble assessed by surface electromyography and inertial measurement unit data.

Hip muscle weakness can be a precursor to or a result of lower limb injuries. Assessment of hip muscle strength and muscle motor fatigue in the clinic is important for diagnosing and treating hip-related impairments. Muscle motor fatigue can be assessed with surface electromyography (sEMG), however sEMG requires specialized equipment and training. Inertial measurement units (IMUs) are wearable devices used to measure human motion, yet it remains unclear if they can be used as a low-cost alternative method to measure hip muscle fatigue. The goals of this work were to (1) identify which of five pre-selected exercises most consistently and effectively elicited muscle fatigue in the gluteus maximus, gluteus medius, and rectus femoris muscles and (2) determine the relationship between muscle fatigue using sEMG sensors and knee wobble using an IMU device. This work suggests that a wall sit and single leg knee raise activity fatigue the gluteus medius, gluteus maximus, and rectus femoris muscles most reliably (p < 0.05) and that the gluteus medius and gluteus maximus muscles were fatigued to a greater extent than the rectus femoris (p = 0.031 and p = 0.0023, respectively). Additionally, while acceleration data from a single IMU placed on the knee suggested that more knee wobble may be an indicator of muscle fatigue, this single IMU is not capable of reliably assessing fatigue level. These results suggest the wall sit activity could be used as simple, static exercise to elicit hip muscle fatigue in the clinic, and that assessment of knee wobble in addition to other IMU measures could potentially be used to infer muscle fatigue under controlled conditions. Future work examining the relationship between IMU data, muscle fatigue, and multi-limb dynamics should be explored to develop an accessible, low-cost, fast and standardized method to measure fatiguability of the hip muscles in the clinic.

Osteochondral injury after acute patellar dislocation in children and adolescents.

BACKGROUND: Acute patellar dislocation (APD) is a common injury in the pediatric patient population and may be associated with a spectrum of soft tissue and osteochondral injuries. This study describes the incidence of osteochondral fracture and associated injury patterns in a pediatric population after first-time APD and assesses functional outcomes after treatment. METHODS: One hundred twenty-two patients, aged 11 to 18 years, who were evaluated after first-time APD over a 10-year period were identified, 46 of whom had confirmed osteochondral injury on magnetic resonance imaging (MRI). Demographic data, including knee affected, mechanism of injury, recurrent dislocation, operations performed, and condition at last follow-up, were retrieved from the medical record. Operative reports and MRI were used to characterize the location of osteochondral injury. The functional outcome of each patient with an osteochondral fracture was assessed using the Pedi-IKDC questionnaire. RESULTS: Forty-six patients, mean age 14.6 years (range, 11 to 18 y), were included. Osteochondral fracture occurred at the patella in 35 patients (76%), the lateral femoral condyle in 11 patients (24%), and at both locations in 3 patients (6.5%). In 21 patients (44%), MRI confirmed osteochondral injury despite the plain radiograph interpretation as negative for fracture. Twenty-six patients (68%) subsequently underwent surgery after injury. Injury to the medial patellofemoral ligament was identified on MRI in 97.8% of patients (45/46). Fifteen patients (32.6%) underwent a concomitant medial repair at the time of surgery. Osteochondral injury to the distal femur on average had a lower International Knee Documentation Committee score than patellar injuries (72.3±18 vs. 91.1±10.2, P<0.003). Femoral osteochondral injury involving the weight-bearing surface (75.27±18.19) scored lower than non-weight-bearing surface injuries (93.22±7.47; P<0.001). CONCLUSIONS: The incidence of osteochondral injury associated with APD is high. Osteochondral fractures may initially go unrecognized on plain radiographs. Patients with weight-bearing lateral femoral condyle injuries had lower short-term functional scores, suggesting that outcomes depend on location of injury. LEVEL OF EVIDENCE: Level IV, diagnostic and therapeutic study.

Reliability of measurements of clavicle shaft fracture shortening in adolescents.

BACKGROUND: A relative indication for surgical treatment of midshaft clavicle fractures is shortening ≥2.0 cm. A standard method for determining shortening with routine clavicle radiographs has not been established. This study evaluated the interobserver and intraobserver reliability when measuring shortening of midshaft clavicle fractures in adolescents. METHODS: We identified all clavicle radiographs of simple midshaft clavicle fractures in adolescents from 2006 to 2010. Thirty-two radiographs were chosen following a power analysis for 7 observers. Each film was measured twice by each evaluator using 2 separate methods. Method 1 was the evaluator's method of choice to determine shortening on the digital radiographs. Method 2 was standardized. Intraclass correlation coefficient and confidence intervals (CI) were calculated to determine interrater reliability, and average differences between the 2 time points with 95% CI were calculated to determine intrarater reliability. RESULTS: Interrater reliability for method 1 was 0.771 (95% CI, 0.655-0.865) and 0.743 (95% CI, 0.604-0.851) at the 2 time points for fair agreement. Interrater reliability for method 2 was 0.741 (95% CI, 0.629-0.842) and 0.685 (95% CI, 0.554-0.805) at the 2 time points, for fair and poor agreement, respectively. Neither method was statistically superior to the other. For method 1, the SD for the measurements averaged 3.1 mm. For method 2, the average SD was 3.0 mm. Intrarater reliability for method 1 was 2.62 mm average difference between the 2 time points (95% CI, 2.24-3.00), and for method 2 it was 3.34 mm average (95% CI, 2.88-3.80). Method 2 had a significantly greater difference at the 2 time points than method 1 (P=0.027). CONCLUSIONS: There is only fair agreement among observers when measuring the shortening of clavicle fractures in adolescents on digital clavicle radiographs by either method described. However, as the average difference among measurers was only 3 mm, this is unlikely to influence clinical decision making. A lack of standardization of measurement in previous studies on clavicle fracture treatment may not represent a significant problem. LEVEL OF EVIDENCE: Level III diagnostic study.

Comparison of titanium elastic nail and plate fixation of pediatric subtrochanteric femur fractures.

BACKGROUND: Studies have demonstrated a higher risk of complications when children with fractures in the proximal third of the femur and length-unstable fractures are treated with titanium elastic nails. Alternative treatment methods include open plating and submuscular plating. We are not aware of any published studies that directly compare titanium elastic nail and plate fixation of pediatric subtrochanteric femur fractures. The purpose of the present study was to retrospectively compare the outcomes and complications of titanium elastic nail and plate fixation of subtrochanteric femur fractures in children and young adolescents. METHODS: A total of 54 children aged 5 to 12 years with subtrochanteric femur fractures treated with titanium elastic nails or plating at 2 institutions between 2003 and 2010 were identified. We retrospectively compared 25 children treated with titanium elastic nails to 29 children treated with either open plating or submuscular plating. Similar to previous studies, a fracture that was located within 10% of the total femur length below the lesser trochanter was classified as subtrochanteric. Outcomes were classified as excellent, satisfactory, or poor. A major complication was defined as any complication that led to unplanned surgery. Minor complications were defined as complications that resolved with nonoperative treatment or did not require any treatment. RESULTS: Outcome scores were significantly better in the plating group (P=0.03), but both groups demonstrated high rates of excellent and satisfactory results. The overall complication rate was significantly higher in the titanium elastic nails group (48%; 12 of 25) when compared with the plating group (14%; 4 of 29) (P=0.008). Patients in the titanium elastic nails group were advanced to full weightbearing significantly earlier (6.6 vs. 9.9 wk) (P=0.005). The major complication rate, length of hospitalization, and time to radiographic union were similar for the 2 groups. CONCLUSIONS: Our results indicate that plate fixation of pediatric subtrochanteric femur fractures is associated with better outcome scores and a lower overall complication rate when compared with titanium elastic nails. LEVEL OF EVIDENCE: Therapeutic Level III.

Congenital Insensitivity to Pain due to a de novo L369P mutation in the SCN11A gene with Heterotrophic Ossification - A Case Report.

Introduction: A male child with congenital insensitivity to pain (CIP) due to a novel de novo L369P mutation in the SCN11A gene was found to have significant bilateral hip flexion contractures, followed by severe heterotopic ossification after contraction release. This is the first report to describe a patient with this specific mutation and subsequent clinical course. Case Report: A male child with CIP due to de novo L369P mutation in the SCN11A gene was found to have significant bilateral hip flexion contractures. The patient underwent bilateral hip contracture releases to improve his standing ability after failure of conservative treatment. In the coming months he developed significant heterotopic ossification that eventually bridged from the left pelvis to the left femur. Conclusion: Heterotrophic ossification (HO) in patients with CIP is a rare and poorly understood clinical manifestation. Our report describes a rare and aggressive manifestation of HO in a patient with CIP.

Patellofemoral joint load and knee abduction/adduction moment are sensitive to variations in femoral version and individual muscle forces.

Torsional profiles of the lower limbs, such as femoral anteversion, can dictate gait and mobility, joint biomechanics and pain, and functional impairment. It currently remains unclear how the interactions between femoral anteversion, kinematics, and muscle activity patterns contribute to joint biomechanics and thus conditions such as knee pain. This study presents a computational modeling approach to investigating the interactions between femoral anteversion, muscle forces, and knee joint loads. We employed an optimal control approach to produce actuator and muscle-driven simulations of the stance phase of gait for femoral anteversion angles ranging from -8° (retroversion) to 52° (anteversion) with a typically developing baseline of 12° of anteversion and implemented a Monte Carlo analysis for variations in lower limb muscle forces. While total patellofemoral joint load decreased with increasing femoral anteversion, patellofemoral joint load alignment worsened, and knee abduction/adduction magnitude increased with both positive and negative changes in femoral anteversion (p < 0.001). The rectus femoris muscle was found to greatly influence patellofemoral joint loads across all femoral anteversion alignments (R > 0.8, p < 0.001), and the medial gastrocnemius was found to greatly influence knee abduction/adduction moments for the extreme version cases (R > 0.74, p < 0.001). Along with the vastus lateralis, which decreased with increasing femoral anteversion (R = 0.89, p < 0.001), these muscles are prime candidates for future experimental and clinical efforts to address joint pain in individuals with extreme femoral version. These findings, along with future modeling efforts, could help clinicians better design treatment strategies for knee joint pain in populations with extreme femoral anteversion or retroversion.

Short-term vancomycin and buffer soaking does not change rabbit achilles tendon tensile material properties.

BACKGROUND: Allograft tendons are commonly used during orthopedic surgery to reconstruct tissue that is severely damaged. Soaking the tendon in an antibiotic solution, specifically vancomycin, has been shown to lower the risk of post-operative infections. While some material properties of tendon and ligament after antibiotic soaking have previously been characterized, extensive sub-failure allograft tendon material properties after soaking in antibiotic solutions have not. METHODS: Forty tendons were dissected from rabbits and soaked in either a phosphate buffered saline (PBS) only solution or vancomycin and PBS solution for five or 30 min. Immediately after soaking, quasi-static tensile experiments were performed in a materials testing system. FINDINGS: Tissue nominal stress, Lagrange strain, toe-region properties and elastic modulus were characterized. For all forty tendons, the average elastic modulus was found to be 455 ± 37 MPa, the average transition strain (from toe-region to linear elastic region) was 0.0487 ± 0.0035, and the average transition stress was 9.71 ± 0.79 MPa. No statistically significant differences in any of these material properties were found across soaking medium or soaking time. INTERPRETATION: From these results, we conclude that soaking an allograft tendon in antibiotic solution for up to 30 min prior to implantation does not change the tensile material properties of tendons, supporting current clinical practice.

Aponeurosis structure-function properties: Evidence of heterogeneity and implications for muscle function.

Aponeurosis is a sheath-like connective tissue that aids in force transmission from muscle to tendon and can be found throughout the musculoskeletal system. The key role of aponeurosis in muscle-tendon unit mechanics is clouded by a lack of understanding of aponeurosis structure-function properties. This work aimed to determine the heterogeneous material properties of porcine triceps brachii aponeurosis tissue with materials testing and evaluate heterogeneous aponeurosis microstructure with scanning electron microscopy. We found that aponeurosis may exhibit more microstructural collagen waviness in the insertion region (near the tendon) compared to the transition region (near the muscle midbelly) (1.20 versus 1.12, p = 0.055), which and a less stiff stress-strain response in the insertion versus transition regions (p < 0.05). We also showed that different assumptions of aponeurosis heterogeneity, specifically variations in elastic modulus with location can alter the stiffness (by more than 10x) and strain (by approximately 10% muscle fiber strain) of a finite element model of muscle and aponeurosis. Collectively, these results suggest that aponeurosis heterogeneity could be due to variations in tissue microstructure and that different approaches to modeling tissue heterogeneity alters the behavior of computational models of muscle-tendon units. STATEMENT OF SIGNIFICANCE: Aponeurosis is a connective tissue found in many muscle tendon units that aids in force transmission, yet little is known about the specific material properties of aponeurosis. This work aimed to determine how the properties of aponeurosis tissue varied with location. We found that aponeurosis exhibits more microstructural waviness near the tendon compared to near the muscle midbelly, which was associated with differences in tissue stiffness. We also showed that different variations in aponeurosis modulus (stiffness) can alter the stiffness and stretch of a computer model of muscle tissue. These results show that assuming uniform aponeurosis structure and modulus, which is common, may lead to inaccurate models of the musculoskeletal system.

Perioperative pain control in pediatric patients undergoing orthopaedic surgery.

Management of perioperative pain is critical in the pediatric patient undergoing orthopaedic surgery. A variety of modalities can be used to manage pain and optimize recovery and patient satisfaction, including nonopioid and opioid analgesia; local anesthetic injection; and regional analgesia such as intrathecal morphine, epidural therapy, and peripheral nerve blocks. Acute pain management can be tailored based on the needs of the patient, the surgical site, and the anticipated level of postoperative pain. A preoperative discussion of the plan for perioperative pain control with the patient, his or her parents, and the anesthesiologist can help manage expectations and maximize patient satisfaction.

Magnetic resonance imaging of acute patellar dislocation in children: patterns of injury and risk factors for recurrence.

BACKGROUND: Acute patellar dislocation is a common traumatic condition of the knee seen in the active adolescent. The patterns of injury to the ligamentous and chondral surfaces following dislocation have not been well defined in the pediatric population. The purpose of this study was to characterize the patterns of medial patellofemoral ligament (MPFL), vastus medialis obliqus (VMO), and osteochondral injury on magnetic resonance imaging (MRI) following first-time acute lateral patellar dislocation in pediatric patients. METHODS: Following approval by the Institutional Review Board, a radiology query was performed to identify all patients between the ages of 11 and 18 years who underwent MRI following an acute first-time patellar dislocation over a 10-year period. The presence and location of injury to the MPFL, VMO, and chondral surfaces were evaluated on MRI images. A retrospective review of the patient's chart was conducted to confirm that clinical history was consistent with an acute patellar dislocation. Demographic data, including age at the time of injury, sex, knee affected, mechanism of injury, and recurrence of dislocation, were retrieved from the chart. The data were analyzed as a single cohort. RESULTS: One hundred and eleven patients, including 56 males and 46 females with a mean age of 14.9 years (range, 11 to 18 y), were included. MRI demonstrated MPFL injury in 87 patients (78.4%). MPFL injury was present at an isolated patellar insertion in 34 patients (31%) and an isolated femoral insertion in 16 patients (14%). MPFL injury at more than one location was present in 37 patients (33%). VMO edema was present in 62 patients (56%), consistent with sprain or tear. Osteochondral fracture was identified in 38 knees (34%), with 25 from the medial patellar facet, 5 from the lateral femoral condyle, and 8 from both locations. CONCLUSIONS: Acute patellar dislocations remain a common injury in pediatric patients. The pattern of injury to the MPFL and VMO on MRI has not been described in a pediatric population. The triad of injury to the MPFL, VMO, and chondral surfaces should be recognized and understood, particularly when surgical reconstruction is necessary. LEVEL OF EVIDENCE: Level III.

Sensitivity and Specificity of MRI in Diagnosing Concomitant Meniscal Injuries With Pediatric and Adolescent Acute ACL Tears.

Background: Preoperative diagnosis of concomitant meniscal tears in pediatric and adolescent patients with acute anterior cruciate ligament (ACL) deficiency is challenging. Purpose: To investigate the diagnostic performance of magnetic resonance imaging (MRI) in detecting meniscal injuries for pediatric and adolescent patients with acute ACL tears. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The authors retrospectively identified patients aged ≤18 years who underwent acute ACL reconstruction between 2006 and 2018 at 2 tertiary academic hospitals. The primary outcomes were arthroscopically confirmed medial, lateral, or any (defined as medial and/or lateral) meniscal tears. To control for chronically deficient knees, patients must have received their MRI study within 4 weeks of injury and must have undergone surgery no more than 8 weeks after their MRI study. Preoperative MRI reports were compared with the gold standard of arthroscopically confirmed tears to calculate sensitivity, specificity, positive predictive value, and negative predictive value. In a secondary analysis, patients were stratified by age into 2 groups (≤13 or ≥14 years), body mass index-for-age data from the Centers for Disease Control were used to classify patients as obese or nonobese, and differences between sensitivity and specificity proportions were analyzed using chi-square test for homogeneity. Results: Overall, 406 patients with a mean age of 15.4 years (range, 10-18 years) were identified. The sensitivity, specificity, positive predictive value, and negative predictive value were as follows: for lateral meniscal (LM) tears, 51.0%, 86.5%, 78.3%, and 65.0%; for medial meniscal tears, 83.2%, 80.6%, 62.3%, and 92.5%; and for any meniscal tear, 75.0%, 72.1%, 81.5%, and 63.8%, respectively. In the stratified analysis, MRI was less specific for the following diagnoses: any meniscal tear in patients aged ≤13 years (P = .048) and LM tears in obese patients (P = .020). Conclusion: The diagnostic ability of MRI to predict meniscal injuries present at acute ACL reconstruction was moderate. Performance was poorest at the lateral meniscus, where MRI failed to detect 97 tears that were found arthroscopically. Specificity was significantly lower in younger patients for any meniscal tear and in obese patients for LM tears.

Risk of reoperation after primary anterior cruciate ligament reconstruction in children and adolescents.

OBJECTIVE: To examine the incidence and risk factors of any-cause reoperation after primary ACLR in children and adolescents. DESIGN: Retrospective Cohort. SETTING: Electronic medical records from a large tertiary care, single institution integrated healthcare delivery system. PATIENTS: Patients were under the age of 18 years and had anterior cruciate ligament reconstruction. They were excluded if they had a multi-ligamentous knee injury or <1 year follow-up. INTERVENTIONS: Patients were further identified to have undergone a subsequent knee operation ipsilaterally or contralateral ACLR. MAIN OUTCOME MEASURES: The rate of any-cause reoperation was our primary outcome measure. RESULTS: The median age was 16. There were 208 females (53.9%) and 178 males (46.1%) included. The median follow-up was 25 months with a minimum of 12 months (interquartile range: 16.0, 46.0). The rate of any-cause reoperation was 34.7%. There was no statistically significant difference between those who underwent reoperation versus those who did not undergo reoperation relative to age, sex, BMI, graft type, or the presence of concomitant meniscal injury. The rates of ipsilateral ACLR and contralateral ACLR at any time during the study period was 8.0% and 10.9% respectively. There was no statistically significant difference for rate of reoperation between graft types, between various concomitant injuries, between those who underwent meniscus repair or no repair. CONCLUSIONS: This study reflects a 34.7% rate of a subsequent knee operation after ACLR in patients younger than 18 years. These findings can be used to inform pediatric patients undergoing primary ACLR on their risk of returning to the operating room.