Microwave Ablation of the Pig Growth Plate: Proof of Concept for Minimally Invasive Epiphysiodesis.

BACKGROUND: Different surgical methods for epiphysiodesis of limb length discrepancy (LLD) have been described. Although these methods are variably effective, they are associated with morbidity (pain and limp) and potential complications. Microwave ablation is a less-invasive opportunity to halt growth by selectively destroying the growth plate via thermal energy to treat LLD in children. QUESTIONS/PURPOSES: In this proof-of-concept study using an in vivo pig model, we asked: (1) What is the durability of response 2 to 4 months after microwave ablation of the tibial growth plate as measured by length and angulation of the tibia via a CT scan? (2) Was articular cartilage maintained as measured by standard histologic staining for articular cartilage viability? METHODS: To develop an in vivo protocol for microwave ablation, we placed microwave antennas adjacent to the proximal tibia growth plate in the cadaveric hindlimbs of 18 3-month-old pigs. To determine the suitable time, we varied ablation from 90 to 270 seconds at 65-W power settings. After sectioning the tibia, we visually assessed for discoloration (implying growth plate destruction) that included the central growth plate but did not encroach into the epiphysis in a manner that could disrupt the articular surface. Using this information, we then performed microwave ablation on three live female pigs (3.5 to 4 months old) to evaluate physiologic changes and durability of response. A postprocedure MRI was performed to ensure the intervention led to spatial growth plate alterations similar to that seen in cadavers. This was followed by serial CT, which was used to assess the potential effect on local bone and growth until the animals were euthanized 2 to 4 months after the procedure. We analyzed LLD, angular deformity, and bony deformity using CT scans of both tibias. The visibility of articular cartilage was compared with that of the contralateral tibia via standard histologic staining, and growth rates of the proximal tibial growth plate were compared via fluorochrome labeling. RESULTS: Eighteen cadaveric specimens showed ablation zones across the growth plate without visual damage to the articular surface. The three live pigs did not exhibit changes in gait or require notable pain medication after the procedure. Each animal demonstrated growth plate destruction, expected limb shortening (0.8, 1.2, and 1.5 cm), and bony cavitation around the growth plate. Slight valgus bone angulation (4º, 5º, and 12º) compared with the control tibia was noted. No qualitatively observable articular cartilage damage was encountered from the histologic comparison with the contralateral tibia for articular cartilage thickness and cellular morphology. CONCLUSION: A microwave antenna placed into a pig's proximal tibia growth plate can slow the growth of the tibia without apparent pain and alteration of gait and function. CLINICAL RELEVANCE: Further investigation and refinement of our animal model is ongoing and includes shorter ablation times and comparison of dynamic ablation (moving the antennae during the ablation) as well as static ablation of the tibia from a medial and lateral portal. These refinements and planned comparison with standard mechanical growth arrest in our pig model may lead to a similar approach to ablate growth plates in children with LLD.

Scheduled methadone reduces overall opioid requirements after pediatric posterior spinal fusion: A single center retrospective case series.

BACKGROUND: Posterior spinal fusion to correct adolescent idiopathic scoliosis is associated with significant postoperative pain. Different modalities have been reported as part of a multimodal analgesic plan. Intravenous methadone acts as a mu-opioid agonist and N-Methyl-D-aspartate (NMDA) antagonist and has been shown to have opioid-sparing effects. Our multimodal approach has included hydromorphone patient-controlled analgesia (PCA) with and without preincisional methadone, and recently postoperative methadone without a PCA. AIMS: We hypothesized that a protocol including scheduled postoperative methadone doses would reduce opioid usage compared to PCA-based strategy. METHODS: A retrospective chart review of patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis between 2015 and 2020 was performed. There were three patient groups: Group PCA received a hydromorphone PCA without methadone; Group PCA + Methadone received preincisional methadone and a hydromorphone PCA; Group Methadone received preincisional methadone, scheduled postoperative methadone, and no PCA. The primary outcome was postoperative opioid use over 72 h. Secondary outcomes included pain scores, sedation scores, and length of stay. RESULTS: Group PCA (n = 26) consumed 0.33 mg/kg (95% CI [0.28, 0.38]) total hydromorphone equivalents, Group PCA + methadone (n = 39) 0.30 mg/kg (95% CI [0.25, 0.36]) total hydromorphone equivalents, and Group methadone (n = 22) 0.18 mg/kg (95% CI [0.15, 0.21]) total hydromorphone equivalents (p = .00096). There were no statistically significant differences between the groups for secondary outcomes. CONCLUSION: A protocol with intraoperative and scheduled postoperative methadone doses resulted in a 45% reduction in opioid usage compared to a PCA-based protocol with similar analgesia after pediatric posterior spinal fusion.

Factors Considered in Ranking Pediatric Orthopedic Fellowship Applicants: A Survey of Program Directors.

The field of orthopedic surgery continues to grow rapidly in popularity. Ninety percent of orthopedic residents pursue fellowship training after residency, representing the highest rate of subspecialty training among surgical specialties. The goal of this study was to determine the factors considered most important by pediatric orthopedic fellowship program directors (PDs) in evaluating applicants and determining a rank list. A web-based survey was sent to all 42 US pediatric orthopedic fellowship programs. The PDs were contacted through publicly accessible email addresses found on program websites or the Pediatric Orthopaedic Society of North America website. Respondents were asked to indicate the fellowship program size and the number of applicants interviewed and ranked each year. The PDs were then asked to rank a list of 12 factors to reflect the relative importance of these criteria in evaluating fellowship applicants. Three emails were sent: 1 at the initial survey release and 2 reminder emails at 2 and 4 weeks. Surveys were anonymous. The overall response rate was 69% (29 of 42). Of the responding PDs, 48% (14 of 29) indicated that the interview was the most important factor in ranking fellowship applicants, whereas 31% (9 of 29) considered the applicant's letters of recommendation most important. Personal connections to the applicant or letter writer and research experience were each considered most important by 10% of responding PDs. Nearly half (48%) of responding PDs considered in-person interviews the most important factor in ranking fellowship applicants. Our results provide useful information for medical students and orthopedic residents planning to pursue fellowship training in pediatric orthopedics. [Orthopedics. 2022;45(4):e207-210.].

Ponseti Clubfoot Casting: Factors That Affect Trainee Competency (Retrospective Observational Study).

INTRODUCTION: This study investigates how previous simulation training and clinical experience affects trainee performance when manipulating a foot, applying a Ponseti clubfoot cast, and performing an Achilles tenotomy on a clubfoot simulator. METHODS: Sixty-four Accreditation Council for Graduate Medical Education orthopaedic trainees participated in the 2017 to 2018 Top Gun (TG) skills competition at the International Pediatric Orthopaedic Symposium. Trainees were judged by expert pediatric orthopaedic surgeons on how they manipulated a clubfoot model, applied a cast, and performed a simulated tendoachilles tenotomy (TAT). An analysis was done to correlate the test variables with a contestant's TG Ponseti score. RESULTS: Twenty-one contestants with previous residency training using synthetic clubfoot models scored higher (P = 0.007) than those trainees without training. Trainees who had applied >10 clubfoot casts and who participated in >10 TATs in training also scored higher (P = 0.038 and P = 0.01, respectively). Thirteen contestants who had previously attended an International Pediatric Orthopaedic Symposium meeting and seven contestants who attended a American Academy of Orthopaedic Surgery clubfoot workshop scored higher (P = 0.012 and P = 0.017 respectively). DISCUSSION: Clinical and previous simulation experience related to the Ponseti method correlated with improved performance on our Ponseti simulation. Trainees who had previous experience with >10 clubfoot casts and >10 TATs scored higher during TG than less experienced trainees.

Sagittal Plane Deformities in Children with SMA2 following Posterior Spinal Instrumentation.

This is a retrospective radiographic review to assess post-operative sagittal plane deformities in patients with Spinal Muscular Atrophy type 2 that had been treated with posterior spinal instrumentation. Thirty-two patients with a history of either spinal fusion (N = 20) or growing rods (N = 12) were identified with an average of 7.6 (2.1-16.6) years post-operative follow-up. Forty percent (13/32) of the patients were identified as having obvious "tucked chin" (N = 4), "tipped trunk" (N = 9), or both (N = 3). Sacral incidence was the only parameter that was statistically significant change between pre-operative or immediate post-operative measurements (66.9° vs. 55.2° p = 0.03). However, at final follow-up, the post-operative thoracic kyphosis had decreased over time in those that developed a subsequent sagittal deformity (24.2°) whereas it increased in those that did not (44.7°, p = 0.008). This decrease in thoracic kyphosis throughout the instrumented levels, resulted in a greater lordotic imbalance (30.4° vs. 5.6°, p = 0.001) throughout the instrumented levels in the group that developed the subsequent cervical or pelvic sagittal deformities. In conclusion, sagittal plane deformities commonly develop outside the instrumented levels in children with SMA type 2 following posterior spinal instrumentation and may be the result of lordotic imbalance that occurs through continued anterior growth following posterior instrumentation.

Variables affecting complication rates in type III paediatric supracondylar humerus fractures.

PURPOSE: Unstable supracondylar humerus (SCH) fractures may have different outcomes as a result of direction of displacement and pin configuration. This study evaluates the impact of fracture displacement, pin configuration and fellowship training on clinical and radiographic outcomes in unstable fractures. METHODS: A total of 99 patients with completely displaced type III fractures were identified at an academic centre and a local community hospital. Patient characteristics and the fellowship training of the treating surgeon were recorded, and injury films documented the direction of displacement. Pin configuration, coronal and sagittal alignment were recorded from postoperative radiographs and at healing. Radiographic outcomes including coronal, sagittal and rotational malunion as well as clinical complications were analyzed. RESULTS: Fractures with direct posterior displacement had a lower composite malunion rate compared with those with posterolateral (PL) or posteromedial (PM) displacement (6.9%, 36.4%, 29.2% respectively; p = 0.019). PM displacement had a higher rate of coronal malunion compared with PL (18.2% versus 0%; post hoc p = 0.024). All-lateral constructs resulted in more rotational malunions (20.9% versus 1.8%; p = 0.002) compared with crossed pinning. PL fractures treated with all-lateral fixation showed a trend toward increased rotational instability or malunion (23.8% versus 1.3%; p = 0.073). Higher composite complication rates were noted in patients treated by surgeons with non-paediatric, non-trauma fellowship training. CONCLUSION: For displaced SCH fractures, all-lateral fixation is associated with higher rates of rotational instability and malunion. Posteromedially and posterolaterally displaced fractures have higher rates of malunion compared with fractures with straight posterior displacement. Fellowship training other than paediatric or trauma was associated with increased complications. LEVEL OF EVIDENCE: Level III.

Is There a Connection Between Attention Deficit Hyperactivity Disorder and Osteochondritis Dissecans?

Background: To determine if children with Osteochondritis Dessicans (OCD) lesions of the distal femur are more likely to have a co-morbid diagnosis of Attention Deficit/ Hyperactivity Disorder (ADHD) than age matched controls and to assess the impact of ADHD on OCD outcomes. Methods: A retrospective chart review of patients treated at a single tertiary care hospital between 2000-2012 was performed. Charts were reviewed for a diagnosis of OCD of the distal femur in all skeletally immature patients (males < 16 years and females < 14 years). These were then screened for a comorbid diagnosis of ADHD. Age-matched controls with anterior knee pain without OCD were then reviewed to determine if ADHD was more common in the OCD population. Treatment and outcomes of the OCD lesions were then compared in children with and without ADHD. Results: The prevalence of ADHD was 23% in patients with OCD lesions and was significantly greater than the 11% found in the anterior knee pain age-matched controls (p<0.05). The average grade of lesions at presentation was similar in both groups (2.2 ADHD vs 2.1 no ADHD) however, at final follow-up, the average OCD grade was significantly worse for children with ADHD (1.4 vs 0.7, p<0.004). Conclusion: There is a significantly higher prevalence of ADHD in children with OCD lesions compared with age-matched controls. This study suggests children that with osteochondritis dessicans and ADHD may not have as favorable treatment course as children without the hyperactivity disorder.Level of Evidence: III.

Trevor's disease of the distal radioulnar joint in two children with achondroplasia.

Two children with achondroplasia who developed an abnormal bony outgrowth at the distal radioulnar joint (DRUJ), indistinguishable from an osteochondroma on histology, but the radiographic appearance, location, and asymmetry suggested the rare diagnosis of dysplasia epiphysealis hemimelica (DEH or "Trevor's disease"). One child experienced symptomatic relief with surgical excision and one was observed clinically due to lack of significant symptoms. These are the first presented cases of DEH in achondroplasia, both affecting the DRUJ. Due to the infrequency of DEH, more research is needed to better understand the potential connection to achondroplasia. For management, we suggest shared surgical decision making based on symptoms.

Is prophylactic formal fusion with implant revision necessary in non-ambulatory children with spinal muscular atrophy and growing rods who are no longer lengthened?

STUDY DESIGN: Single center, retrospective chart review. OBJECTIVES: To determine if routine posterior spinal fusion (PSF) is unnecessary in non-ambulatory growing rod graduates with SMA. Most non-ambulatory children with SMA develop early-onset scoliosis (EOS). Posterior growing rods (GR) have been shown safe and effective in managing spinal deformities in these children. The best management of these children, once graduated from their GR, is currently unknown. In this study, we report the clinical results of managing these children without routine definitive fusion following a course of GR treatment. METHODS: A single-center, retrospective chart and radiographic review was performed on children with SMA treated with posterior distraction GR, with a two-year minimum follow-up since final lengthening. Electronic medical records and radiographs were reviewed for demographic variables, Cobb measurements, implant revisions, occult radiographic implant failure, symptomatic failure, and/or conversion to PSF. RESULT: 12 patients (2 type 1, 9 type 2, 1 type 1/2) met inclusion criteria. Mean age at growing rod insertion was 6.2 years of age (range 4.1-8.2) and age at final lengthening 10.3 years of age (range 9.3-11.9). The mean time between last lengthening and latest clinical or radiographic review was 5.5 (range 2.1-9.0) years. Average mean pre, post, final Cobb angles were 71°, 27° (p < 0.001), 25°. Following final lengthening, only one patient required hardware revision and conversion to definitive fusion in attempts to alleviate chronic hip pain, which was unsuccessful. One additional patient was found to have an occult rod failure that has not required treatment. CONCLUSION: While limited by sample size, this single-center cohort of non-ambulatory SMA patients with EOS treated with similar constructs suggests that routine, definitive fusion in SMA GR graduates may be unnecessary. LEVEL OF EVIDENCE: Level IV.

Does an intrathecal baclofen pump impact scoliosis progression and complicate posterior spine fusion in patients with cerebral palsy?

STUDY DESIGN: Retrospective comparative study. OBJECTIVES: In patients with cerebral palsy (CP), we determine the impact of intrathecal baclofen pumps (ITBPs) on scoliosis curve progression before posterior spine fusion (PSF) and its effects on surgical outcome. BACKGROUND: Children with CP can have rapid scoliosis progression, and high rates of surgical complications can be encountered. It is unknown whether the presence of pre-existing ITBP results in more difficult surgery and higher complication rates in similarly affected children. METHODS: This is a single-center retrospective study of CP patients undergoing PSF over a 15-year period. Demographics, comorbidities, curve magnitudes, and surgical methods were compared between patients with ITBP and those without. Postoperative complications, length of intensive care unit/hospital stay, drain use and output volume, and need for further surgery were also compared. Curve progression analysis after ITBP placement was performed on a subgroup of patients with high-quality consistent radiographs. RESULTS: Nineteen patients with ITBP and 49 patients without ITBP met inclusion criteria. Age, comorbidities, number of levels fused, and fixation techniques during PSF were not significantly different between cohorts. ITBP patients were more likely to have PSF with osteotomy (p = 0.022). Increased intraoperative neurosurgical consultations were found for patients with ITBP (42.1% vs. 4.0%; p < 0.001). Median surgical time was 1.2 h greater in patients with ITBP (6.7 vs. 5.5 h, p = 0.039). There was no difference in hospital course and complications in patients with ITBP and those without ITBP. Thirty-one patients without ITB were compared with 15 ITBP patients for curve progression before PSF, demonstrating a mean rate of scoliosis progression of 9.6° ± 6.7°/year and 14.8° ± 9.1°/year (p = 0.0346), respectively. CONCLUSION: The presence of an ITBP appears to be associated with the increase in scoliosis progression; and these patients will likely have a more challenging spine fusion. Fortunately, the final outcome is not affected by ITBP. LEVEL OF EVIDENCE: Level III.

Cervical Spine Injury Following Thoracic Spinal Fusion for Adolescent Idiopathic Scoliosis.

Spinal fusion for adolescent idiopathic scoliosis (AIS) can have many potential complications, including spinal cord injury. Most often, spinal cord injury occurs in the region of surgery due to direct mechanical trauma. Vascular compromise in this area may also occur due to a high degree of correction or excessive distraction of the spine. In these cases, the impairment of spinal cord function is often detected intraoperatively with spinal cord monitoring and confirmed in the immediate postoperative period. Injury to the spinal cord above the level of instrumentation is rare. We review the clinical history and outcome of a female adolescent who underwent posterior spinal fusion (PSF) for AIS and developed a cervical spine injury 12 hours postoperatively. The patient is a 13-year old female who underwent PSF for AIS from T1 to L1 for progressive scoliosis measuring over 53 degrees in her right thoracic curve. During surgery, she had modest correction with minimal blood loss and with normal intraoperative motor evoked and somatosensory evoked potentials. The immediate postoperative examination was neurologically intact. Twelve hours later, she developed weakness and tingling in her right upper extremity. Magnetic resonance imaging (MRI) of the cervical spine demonstrated myelomalacia on the right side of the spinal cord at the C5-7 levels. Cervical spine injuries are rare following lower-level fusions, however, these injuries can occur and it is important to be vigilant in monitoring patients for these symptoms. The exact mechanism is unknown and may include a combination of postoperative hypotension with altered vascular anatomy from cord stretch and abnormal cervical positioning.

Variation Among Pediatric Orthopaedic Surgeons When Treating Medial Epicondyle Fractures.

BACKGROUND: Medial epicondyle fractures are a common pediatric and adolescent injury accounting for 11% to 20% of elbow fractures in this population. This purpose of this study was to determine the variability among pediatric orthopaedic surgeons when treating pediatric medial epicondyle fractures. METHODS: A discrete choice experiment was conducted to determine which patient and injury attributes influence the management of medial epicondyle fractures by pediatric orthopaedic surgeons. A convenience sample of 13 pediatric orthopaedic surgeons reviewed 60 case vignettes of medial epicondyle fractures that included elbow radiographs and patient/injury characteristics. Displacement was incorporated into the study model as a fixed effect. Surgeons were queried if they would treat the injury with immobilization alone or open reduction and internal fixation (ORIF). Statistical analysis was performed using a mixed effect regression model. In addition, surgeons filled out a demographic questionnaire and a risk assessment to determine if these factors affected clinical decision-making. RESULTS: Elbow dislocation and fracture displacement were the only attributes that significantly influenced surgeons to perform surgery (P<0.05). The presence of an elbow dislocation had the largest impact on surgeons when choosing operative care (ß=-0.14; P=0.02). In addition, for every 1 mm increase in displacement, surgeons tended to favor ORIF by a factor of 0.09 (P<0.01). Sex, mechanism of injury, and sport participation did not influence decision-making. In total, 54% of the surgeons demonstrated a preference for ORIF for the included scenarios. On the basis of the personality Likert scale, participants were neither high-risk takers nor extremely risk adverse with an average-risk score of 2.24. Participant demographics did not influence decision-making. CONCLUSIONS: There is substantial variation among pediatric orthopaedic surgeons when treating medial epicondyle fractures. The decision to operate is significantly based on the degree of fracture displacement and if there is a concomitant elbow dislocation. There is no standardization regarding how to treat medial epicondyle fractures and better treatment algorithms are needed to provide better patient outcomes. LEVEL OF EVIDENCE: Level V.

Open Vs. Closed Reduction in Type 2 Lateral Condyle Fractures.

Background: Lateral condyle fractures are associated with high morbidity due to their risk of nonunion and avascular necrosis (AVN). This study aims to assess the outcomes between closed reduction and the more traditional open techniques for operative fractures. Methods: All lateral condyle fractures that required operative fixation (pins or screws) over a ten-year period were included. We compared open versus closed reduction for OR time, infection rate, AVN, nonunion, premature physeal closure, ulnohumeral angle, and interepicondylar width (IEW). Results: 28 patients were identified in the closed reduction group while 41 were identified in the open reduction group. Average displacement at surgery for these two groups was significantly different at 3.95mm for the closed group and 9.47mm for the open group (p<0.0001). Operating room time was significantly greater for the open reduction group by an average of 45 minutes (p <0.0001). Additionally, the closed reduction group was significantly less likely to require postoperative admission compared to the open reduction group (p=0.0004). There were no significant differences between the two groups with regard to abnormal ulnohumeral angles, infection rates, avascular necrosis, nonunion, lateral spur formation, premature physeal closure, or reoperation rate. Conclusions: The significant differences in OR time and post-operative admission make closed reduction the preferred approach from a hospital system quality improvement standpoint.Level of Evidence: IV.

The Use of Triphasic Bone Graft for the Treatment of Pediatric Bone Cysts: Experience at 2 Institutions.

Unicameral/aneurysmal bone cysts can lead to pain, fracture, and limb deformity. In this study, the authors evaluated the outcome of triphasic bone graft to treat unicameral/aneurysmal bone cysts. They retrospectively evaluated 41 immature patients from a prospectively enrolled cohort from 2 institutions treated from May 9, 2007, to November 1, 2014. Medical record review and evaluation of radiographs and computed tomography scans were performed. The authors characterized replacement of the material by normal bone or recurrent cyst at final follow-up. They recorded rates of fractures and complications after treatment. Twenty-nine patients were treated in Wisconsin, and 12 patients were treated in Florida. Average follow-up was 2.8 years. At follow-up, 13 of 41 patients had cyst recurrence. Three patients had fracture after initial treatment; 2 were treated surgically. Two of 9 patients with extraosseous bone graft had soft tissue swelling, and 1 required debridement. Complications did not differ by cyst type, location, sex, age, or use of internal fixation. For 27 patients with at least 2-year follow-up, percent fill of triphasic bone graft at initial surgery correlated with rate of recurrence at final follow-up: 15 of 27 patients with no cyst recurrence at final follow-up had a mean of 100% initial fill, and 12 of 27 with cyst recurrence at final follow-up had a mean of 90% initial fill (P=.048). Using triphasic bone graft for the treatment of unicameral/aneurysmal bone cysts, the authors observed a 7% rate of clinical recurrence (3 of 41 had fracture). Because this material has the potential to be locally inflammatory, efforts are needed to keep it within the bone. [Orthopedics. 2018; 41(5):e705-e712.].

Predictability of Clinical Knowledge Through Mobile App-based Simulation for the Treatment of Pediatric Septic Arthritis: A Pilot Study.

BACKGROUND: Recently the American Board of Orthopaedic Surgery and the Accreditation Council of Graduate Medical Education have identified the treatment of septic arthritis of the hip in children as a milestone skill for all US orthopaedic residents. The purpose of this study was to test correlation between clinical knowledge and examination score on a mobile app-based training module for the treatment of pediatric septic hip arthritis. METHODS: A 4-part simulation model on surgical decision-making associated with the treatment of pediatric septic arthritis was developed through expert consensus. Orthopaedic trainees participating in the "Top Gun" program of the 2015 and 2016 International Pediatric Orthopaedic Symposiums were recruited to participate in this pilot study. Trainees completed a presimulation quiz on their knowledge of diagnosis, arthrocentesis, and surgical irrigation and debridement on a pediatric patient presenting with septic arthritis of the hip. Trainees then completed the 4-part simulation on the mobile app. Pearson correlation analysis was used to assess the relationship between the quiz and the simulation. RESULTS: A total of 53 orthopaedic residents and fellows participated in the simulation. Median quiz score was 87 points [interquartile range (IQR), 81 to 94] before the intervention and 100 points (IQR, 94 to 100) postintervention. The median simulation test score was 89 (IQR, 81 to 92) which demonstrated a positive correlation with the postintervention quiz (r=0.44, P<0.001). The preintervention metrics demonstrated a positive correlation with postintervention metrics (r=0.53, P<0.001). CONCLUSIONS: This study revealed a statistically significant positive correlation between the mobile app simulation and the clinical knowledge of the participants, as well as the ability to improve knowledge about a procedure during the testing period. These findings support the ability for the mobile app to test clinical knowledge. In the current environment of decreased work hours and patient exposure for orthopaedic trainees, mobile app-based simulation has the potential to safely aid in assessment of orthopaedic residents and fellows.

Efficiency and Safety: The Best Time to Valve a Plaster Cast.

BACKGROUND: The act of applying, univalving, and spreading a plaster cast to accommodate swelling is commonly performed; however, cast saws can cause thermal and/or abrasive injury to the patient. This study aims to identify the optimal time to valve a plaster cast so as to reduce the risk of cast-saw injury and increase spreading efficiency. METHODS: Plaster casts were applied to life-sized pediatric models and were univalved at set-times of 5, 8, 12, or 25 minutes. Outcome measures included average and maximum force applied during univalving, blade-to-skin touches, cut time, force needed to spread, number of spread attempts, spread completeness, spread distance, saw blade temperature, and skin surface temperature. RESULTS: Casts allowed to set for ≥12 minutes had significantly fewer blade-to-skin touches compared with casts that set for <12 minutes (p < 0.001). For average and maximum saw blade force, no significant difference was observed between individual set-times. However, in a comparison of the shorter group (<12 minutes) and the longer group (≥12 minutes), the longer group had a higher average force (p = 0.009) but a lower maximum force (p = 0.036). The average temperature of the saw blade did not vary between groups. The maximum force needed to "pop," or spread, the cast was greater for the 5-minute and 8-minute set-times. Despite requiring more force to spread the cast, 0% of attempts at 5 minutes and 54% of attempts at 8 minutes were successful in completely spreading the cast, whereas 100% of attempts at 12 and 25 minutes were successful. The spread distance was greatest for the 12-minute set-time at 5.7 mm. CONCLUSIONS: Allowing casts to set for 12 minutes is associated with decreased blade-to-skin contact, less maximum force used with the saw blade, and a more effective spread. CLINICAL RELEVANCE: Adherence to the 12-minute interval could allow for fewer cast-saw injuries and more effective spreading.

Residual Equinus After the Ponseti Method: An MRI-based 3-Dimensional Analysis.

BACKGROUND: Residual equinus deformity is present in up to 20% of clubfeet treated by the Ponseti method. These patients may require surgical release to restore dorsiflexion. Despite complete posterior release; persistent intraoperative equinus may be present and suggest concurrent joint incongruity. The purpose of this study was to characterize differences in ankle morphology in toddlers with residual equinus following the Ponseti method. METHODS: Preoperative magnetic resonance imaging (MRI) data from 10 patients who underwent reconstruction (17 feet; 7 bilateral, 3 unilateral clubfeet) for persistent equinus were compared with 16 age-matched controls. Through reverse engineering software, MRI data were used to generate 3-dimensional (3D) models. Four talus-based measures were performed on both MRI data and 3D models-neck depth, neck angle, width, and length. Models were also used to calculate talus volume and arc of curvature (plafond and talar dome). Standard statistical analyses were performed. RESULTS: Talus volumes, width, and length were less in clubfeet then in control feet. Although some measures were significant there was no mismatch with the ankle mortise dimensions or arc curvature that could account for any decrease in dorsiflexion. We found that from MRI measures the clubfoot neck depth was 2.3 versus 3.6 mm in controls (P<0.001) and from 3D modeling the clubfoot neck depth was 2.3 and 3.5 mm in controls (P=0.003). With 3D modeling talus clubfoot neck angle was 153.7 versus 140.4 degrees in controls (P=0.01). The clubfoot neck angle obtained from MRI measures were also different yet not significant [126.6 in clubfeet versus 122.5 degrees in controls (P=0.12)]. CONCLUSIONS: In comparison to age-matched feet; we have noted a decrease in talar neck depth and an obtuse talar neck angle in clubfeet treated in the manner of Ponseti. This may result in anterior ankle impingement and be the cause of residual equinus despite posterior release. In these procedures, the surgeon should recognize this possibility when the amount of dorsiflexion is less than expected. LEVEL OF EVIDENCE: Level III-case control study.

Guided Growth Implant Failure is a Result of Cyclic Fatigue: Explant Analysis With Scanning Electron Microscopy.

BACKGROUND: Guided growth is often used to correct limb deformity and yet implant screw failure in modular systems has been reported. There have been no reports of plate failure and we do not know the exact mode of failure when screws do break. METHODS: We report the first published case of a fractured plate in a modular plate and screw construct that was used to correct Blount disease in a child through guided growth. The implants were removed and analyzed for method of failure using scanning electron microscopy. RESULTS: Scanning electron microscopy of the explant confirms that the mode of failure was not a result of static tension from growth. Rather, analysis confirms cyclic fatigue that led to crack propagation across the anterior side of the plate until overload caused complete plate failure. CONCLUSIONS: This analysis confirms an in vivo cyclic compression-relaxation of the growth plate presumably to weight-bearing, and that when excessive may lead to implant failure as seen here in this case. LEVEL OF EVIDENCE: Level V.

Radiographic and Respiratory Effects of Growing Rods in Children With Spinal Muscular Atrophy.

BACKGROUND: Respiratory weakness and spinal deformity are common in patients with spinal muscular atrophy (SMA). Posterior (distraction type) growing rods have recently gained favor as a treatment option in this population, due to their ability to prevent spinal deformity progression and their potential to allow lung volumes to increase over time. The objective of this study was to determine the impact of posterior growing rods on the spinal alignment and respiratory function in children with SMA with intermediate term follow-up. METHODS: A single center, retrospective review was performed on SMA patients treated with growing rods, inserted between 2004 and 2010, with a minimum of 2-year follow-up. SMA type, changes in the route of bi-level positive airway pressure respiratory support and the amount of time receiving respiratory support are reported. Pulmonary function tests (PFTs) and radiographs were reviewed and data evaluated preinsertion, postinsertion, and at latest follow-up. RESULTS: Sixteen children with SMA (5 type I, 11 type II) met inclusion criteria. The average age of insertion was 5.8 (±1.5) years, the median number of lengthenings was 4 (range, 3 to 5), and the median time between insertion and last clinical review was 4.7 (range, 2.7 to 9.5) years. Radiographic review demonstrated significant (P<0.05) improvements in the following: Spinal curve magnitude, pelvic obliquity, space available for the lung, rib vertebral angle difference, and thoracic kyphosis following growing rod implantation. Thoracic and lumbar height and chest width and depth increased significantly (P<0.05) over the lengthening process. None of the patients initially required more than noninvasive positive pressure ventilation support. Fifteen of the 16 experienced no changes in their noninvasive positive pressure ventilation support needs throughout the study duration, requiring support only at night and naps. Serial PFTs were available for 6 children with SMA type II. PFTs demonstrated significant improvements in absolute forced vital capacity (FVC), minimal changes in the maximal inspiratory and expiratory pressures, and a gradual worsening of percent predicted FVC. CONCLUSIONS: Clinical respiratory support requirements appear to stabilize following the insertion and lengthening of posterior based growing rods in the SMA population. Similar to previous studies, increased spinal height and thoracic cavity size were noted throughout the process. Despite an increasing absolute FVC, the percent predicted FVC diminished over time. LEVEL OF EVIDENCE: Level IV-therapeutic.