Quantitative Skeletal Imaging and Image-Based Modeling in Pediatric Orthopaedics.

PURPOSE OF REVIEW: Musculoskeletal imaging serves a critical role in clinical care and orthopaedic research. Image-based modeling is also gaining traction as a useful tool in understanding skeletal morphology and mechanics. However, there are fewer studies on advanced imaging and modeling in pediatric populations. The purpose of this review is to provide an overview of recent literature on skeletal imaging modalities and modeling techniques with a special emphasis on current and future uses in pediatric research and clinical care. RECENT FINDINGS: While many principles of imaging and 3D modeling are relevant across the lifespan, there are special considerations for pediatric musculoskeletal imaging and fewer studies of 3D skeletal modeling in pediatric populations. Improved understanding of bone morphology and growth during childhood in healthy and pathologic patients may provide new insight into the pathophysiology of pediatric-onset skeletal diseases and the biomechanics of bone development. Clinical translation of 3D modeling tools developed in orthopaedic research is limited by the requirement for manual image segmentation and the resources needed for segmentation, modeling, and analysis. This paper highlights the current and future uses of common musculoskeletal imaging modalities and 3D modeling techniques in pediatric orthopaedic clinical care and research.

Is peak hamstrings muscle-tendon length criterion a sufficient indicator to recommend against surgical lengthening of hamstrings?

BACKGROUND: Excessive knee flexion during stance in children with cerebral palsy is often treated by surgical hamstrings lengthening. Pre-operative hamstrings muscle-tendon length can be estimated from kinematics and often used for decision making to rule out surgical lengthening if peak hamstrings muscle-tendon length is 'Not Short'. RESEARCH QUESTION: If peak hamstrings muscle-tendon length is within two standard deviations of typical, is that a sufficient indicator to rule out surgical hamstrings lengthening? METHODS: Three motion analysis centers retrospectively identified children with cerebral palsy, age 6-17 years, who had consecutive gait analyses with knee flexion at initial contact > 20° and popliteal angle > 35° at initial study. Three groups were considered: Medial Hamstrings Lengthening (MHL), Medial and Lateral Hamstrings Lengthening (MLHL), no surgical intervention (Control). Peak hamstrings muscle-tendon length at initial gait study was computed and categorized as 'Short' or 'Not Short'. Two outcomes variables were considered: change in peak knee extension (PKE) and change in pelvic tilt. Univariate comparisons of all variables were assessed along with a multivariate stepwise regression analysis to identify pre-operative characteristics that may predict post-operative improvement. RESULTS: 440 individuals met inclusion criteria. Percentage of individuals with improved PKE by grouping were- MHL-'Short': 60%, MHL-'Not Short': 65%, MLHL-'Short': 74%, MLHL-'Not Short': 74%, Control 'Short': 20%, Control 'Not Short': 19%. Percentage of individuals with worsened pelvic tilt were- MHL-'Short': 25%, MHL-'Not Short': 11%, MLHL-'Short': 42%, MLHL-'Not Short': 21% with significantly more individuals in MHL-'Short' subgroup compared to MHL-'Not Short'. Multivariate analysis suggested that pre-operative pelvic tilt and weak hip extensor strength have the largest effect on predicting post-operative increase in APT. Peak muscle-tendon length was not a significant predictor of post-operative knee kinematics or increase in APT. SIGNIFICANCE: This study suggests that hamstrings muscle-tendon length criteria by itself is not a sufficient indicator to recommend against hamstrings lengthening.

The long-term effects of aggressive spasticity reducing treatment, including selective dorsal rhizotomy, on joint kinematic outcomes of persons with cerebral palsy.

BACKGROUND: Selective dorsal rhizotomy (SDR) creates a large and permanent reduction of spasticity for children with cerebral palsy (CP). Previous SDR outcomes studies have generally lacked appropriate control groups, had limited sample sizes, or reported short-term follow-up, limiting evidence for improvement in long-term gait function. RESEARCH QUESTION: Does aggressive spasticity management for individuals with CP improve long-term gait kinematics (discrete joint kinematics) compared to a control group of individuals with CP with minimal spasticity management? METHODS: This study was a secondary analysis - focused on joint-level kinematics - of a previous study evaluating the long-term outcomes of SDR. Two groups of participants were recruited based on a retrospectively completed baseline clinical gait study. One group received aggressive spasticity treatment including a selective dorsal rhizotomy (Yes-SDR group), while the other group had minimal spasticity management (No-SDR group). Both groups had orthopedic surgery treatment. Groups were matched on baseline spasticity. All participants prospectively returned for a follow-up gait study in young adulthood (greater than 21 years of age and at least 10 years after baseline). Change scores in discrete kinematic variables from baseline to follow-up were assessed using a linear model that included treatment arm (Yes-SDR, No-SDR), baseline age, and baseline kinematic value. For treatment arm, 5° and 5 Gait Deviation Index points were selected as thresholds to be considered a meaningful difference between treatment groups. RESULTS: At follow-up, there were no meaningful differences in pelvis, hip, knee, or ankle kinematic variable changes between treatment arms. Max knee flexion - swing showed a moderate treatment effect for Yes-SDR, although it did not reach the defined threshold. SIGNIFICANCE: Aggressive spasticity treatment does not result in meaningful differences in gait kinematics for persons with cerebral palsy in young adulthood compared to minimal spasticity management with both groups having orthopedic surgery.

Patient-reported Outcomes of Adolescents Treated With Guided Growth to Correct Idiopathic Genu Valgum.

BACKGROUND: Guided growth is commonly used to treat frontal plane alignment deformities in skeletally immature individuals. Treatment aims are to correct the biomechanical loading of the knee and to avoid more invasive surgery that would be required after skeletal maturity. There is little published evidence of pain perception or functional limitations in this population. In addition, the intervention has the potential to worsen pain and function with hardware implantation, and symptoms may not fully resolve after removal. Understanding of pain and function limitations in this population is important to guide the clinical expectations. METHODS: Individuals with idiopathic knee genu valgum who underwent hemiepiphysiodesis with tension plate constructs were identified through a medical records database search. Patient-reported outcomes measurement information system Physical Function/Mobility and Pain Interference domain scores were assessed before hemiepiphysiodesis, immediately before hardware removal, and after hardware removal. Radiographs were also assessed at these times to record the zones and angles of deformity and correction. RESULTS: Twenty-eight subjects (53 operative limbs) contributed to the analysis. Mobility and pain interference as measured by the patient-reported outcomes measurement information system were below typical values in a small percentage of the population studied, only 3.6% scored in the moderate and none in the severe categories for both domains. Valgus by radiographic zone was corrected in all patients without significant rebound at follow-up. Compared with preoperative levels, mobility scores improved before hardware removal. Pain Interference scores improved both before hardware removal and at the final follow-up. CONCLUSIONS: Frontal plane knee deformities in the idiopathic population do not cause pain or limit mobility in most subjects. This is critical information, emphasizing that surgical decisions may be made based on the deformity alone, presence of symptoms, and possible future morbidity secondary to valgus deformity. If surgery is postponed because an individual is asymptomatic, the window for correction with guided growth may be lost. Individuals undergoing hemiepiphysiodesis can expect that their pain and function will not be worse during the time that hardware is in place and that surgery is likely to improve any pain they may be experiencing. LEVEL OF EVIDENCE: Level III; retrospective comparative study.

Discrimination between hereditary spastic paraplegia and cerebral palsy based on gait analysis data: A machine learning approach.

BACKGROUND: There is no current consensus on how to differentiate between hereditary spastic paraplegia and spastic cerebral palsy on the basis of clinical presentation. Several previous studies have investigated differences in kinematic parameters obtained from clinical gait analysis. None have attempted to combine multiple gait and physical exam measures to discriminate between these two diagnoses. This study aims to investigate the ability of a machine learning approach using data from clinical gait analysis to differentiate these cohorts. METHODS: A retrospective analysis of a gait database compiled a dataset of 179 gait and physical exam variables from 28 individuals (62 analyses) diagnosed with hereditary spastic paraplegia and 678 (1504 analyses) with bilateral spastic cerebral palsy. This data was used in a Bayesian additive regression tree (BART) analysis classified by medical record diagnosis. A 10-fold cross validation generated probabilistic distribution that each analysis was from an individual carrying the hereditary spastic paraplegia diagnosis. A diagnostic probability cutoff threshold balanced type I and type II errors. Predicted versus actual diagnoses were classified into a contingency table. RESULTS: The algorithm was able to correctly classify the two diagnoses with 91% specificity and 90% sensitivity. CONCLUSIONS: A machine learning approach using data from clinical gait analysis was able to distinguish participants with hereditary spastic paraplegia from those with bilateral spastic cerebral palsy with high specificity and sensitivity. This algorithm can be used to assess if individuals seen for gait disorders who do not yet have a definitive diagnosis have characteristics associated with hereditary spastic paraplegia. The results of the model inform the decision to suggest genetic testing to either confirm or refute the diagnosis of hereditary spastic paraplegia.

Outcome of Gastrocnemius Soleus Facial Lengthening in Ambulatory Patients With Cerebral Palsy.

BACKGROUND: Treatment of equinus contractures in children with cerebral palsy (CP) varies across centers. Existing literature utilizes mixed study populations with a variety of procedures. As such, there is limited knowledge regarding recurrence rates and efficacy of a single procedure performed on a homogenous cohort. Here we retrospectively evaluate outcomes from gastroc soleus fascial lengthenings (GSFL) performed at 2 centers with consistent approaches in both patient selection and operative technique. METHODS: Subjects meeting inclusion criteria including CP diagnosis, ambulation status, and minimum follow-up criteria were identified. Revision rate was reported based on need for additional calf lengthening procedures. Functional outcomes were evaluated using physical exam measures and selected variables from computational gait analysis. Outcomes factors were identified by comparing revised subjects to unrevised. Longitudinal outcomes of index surgeries were assessed by comparing preoperative functional data to short-term, mid-term, and long-term data. RESULTS: A total of 64 subjects with 87 limbs met inclusion criteria. In all, 25% of subjects and 21% of limbs went on to revision. Factors influencing revision were age at index surgery and gross motor function classification system (GMFCS) level. More than half of revised limbs had index surgery before age 7. Revision rates for subjects less than 7 were 44% compared with a 17% revision rate for ages 7 to 12, and a 4% revision rate on children older than 12. GMFCSIII subjects had significantly higher revision rates (43%) compared with GMFCSII (18%) and GMFCSI (11%) subjects. Ankle range of motion measures improved significantly with GSFL and most maintained improvements at all time periods. GSFL did not lead to significant calcaneal gait or crouch. CONCLUSIONS: This study evaluates long term efficacy of GSFL to address equinus in ambulatory children with CP. Overall revision rates are similar to previous reports for GSFL and other calf lengthening procedures. This information may be useful in setting expectations and counselling families. Younger subjects and those with more severe involvement are more likely to need revision surgery, with these factors compounding the likelihood in the younger GMFCSIII child. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Factors Influencing Outcomes of the Dysplastic Hip in Nonambulatory Children With Cerebral Palsy.

BACKGROUND: Hip dysplasia in the nonambulatory child with spastic cerebral palsy (CP) is a common condition not always effectively treated with conservative measures even when recognized early. Optimal surgical intervention strategies and timing are not clear from previous studies. Contralateral hips with less severe subluxation in these patients also often undergo surgery and little is known of outcomes of these less severe hips. This study aims to clarify treatment factors related to long term success following hip surgery for subluxation in nonambulatory children with CP. METHODS: A total of 183 nonambulatory subjects with CP and a minimum of 2-year follow-up were included. All subjects underwent varus rotational osteotomy of the femur; other surgical factors considered were addition of pelvic osteotomy (PO), capsulorrhaphy, and soft tissue releases. Additional factors studied were age at index surgery, sex, and unilateral versus bilateral surgery. Severely subluxated (SS) hips, defined as having >50% migration, were studied separately from contralateral nonsevere hips. Surgeries were deemed successful if final follow-up indicated a migration of <25%; patients with any revision surgeries or >25% migration were categorized as failures. RESULTS: A 60% success rate was found in SS hips and a 68% success rate in nonsevere hips. Age at index surgery did not influence success rates in SS hips. In the nonsevere hips, success was associated with index surgery at older age. The addition of a PO was the only concomitant procedure demonstrated to improve outcomes. In SS hips, those with a successful outcome were 2.5 times more likely to have had a PO. The addition of capsulorrhaphy had a negative effect on the entire group, reducing odds of success to 0.8. No other factors were significant. CONCLUSIONS: The findings from this multicenter retrospective study suggest that PO be added to varus rotational osteotomies in patients with severe hip subluxation. Surgery should be undertaken for severe dysplasia without concern for age. The addition of capsulorrhaphy does not improve rate of success. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Utilization and efficacy of computational gait analysis for hamstring lengthening surgery.

A retrospective analysis of computational gait studies performed in a single lab over a 12 year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 Subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome.

The Occurrence of Occult Acetabular Dysplasia in Relatives of Individuals With Developmental Dysplasia of the Hip.

BACKGROUND: This study sought to determine the hip pathology of family members of patients with developmental dysplasia of the hip (DDH). The authors evaluated 120 people from 19 families known to have at least 1 member with surgically treated DDH. Each individual's functional outcome scores and pelvic radiographs were assessed for hip symptoms or pathology. METHODS: Using a genetic population database and a pediatric hospital patient population, 19 families with high rates of DDH were identified. All family members (n=120) underwent physical examination, radiographic assessment, and completion of outcome instruments [American Academy of Orthopedics (AAOS) Hip and Knee; Harris Hip Score (HHS); and Western Ontario and McMaster Universities Arthritis Index (WOMAC)]. RESULTS: The 120 subjects ranged from 1 to 84 years, 34 had orthopaedically treated DDH. Of the remaining 86 supposedly normal subjects, 23 (27%) had occult acetabular dysplasia (OAD) as defined by center edge angle (CEA) <20 and/or a Severin score of III or greater. Sixty percent of the 86 individuals were less than 30 years old, 74% of the OAD group were less than 30. Outcome scores of the treated DDH patients (AAOS, HHS, and WOMAC) were worse on the involved side regardless of age. Over age 30 individuals with OAD had statistically significant decreases in their AAOS Hip and Knee and WOMAC scores on the dysplastic side, but their HHS scores were not significantly different. CONCLUSIONS: Twenty-seven percent of first-degree and second-degree relatives of patients with DDH had unsuspected radiographic acetabular dysplasia in our study. Most of the subjects with OAD were younger than 30. After age 30, many of these patients developed symptoms. CLINICAL RELEVANCE: In families with a significant history of DDH, radiographic screening of siblings of patients with DDH to define OAD may be prudent. LEVEL OF EVIDENCE: Level I­diagnostic study.

Total hip arthroplasty, hip osteoarthritis, total knee arthroplasty, and knee osteoarthritis in patients with developmental dysplasia of the hip and their family members: a kinship analysis report.

BACKGROUND: Developmental dysplasia of the hip (DDH) is a familial condition with a wide phenotypic expression. Families with high rates of DDH may have individuals with subtle phenotypic expression that can progress to osteoarthritis and require total hip arthroplasty (THA). This study compares the rates of THA in relatives of individuals with DDH with individuals in control families. METHODS: Probands with a diagnosis of DDH were identified using medical records linked to the Utah Population Database. Ten age-matched and sex-matched controls were randomly selected from a pool of unaffected individuals within the Utah Population Database. Diagnostic and procedural codes were used to determine the incidence of hip and knee osteoarthritis (HOA and KOA) and of THA and total knee arthroplasty (TKA) among the cases and controls and their relatives. Relative risks (RR) for HOA and KOA and for THA and TKA were calculated for the probands/controls and their family members. RESULTS: The RR of HOA was significantly increased in probands (RR=82.4; P<2e-16), their parents (R=2.22; P=0.0003), and in their grandparents (RR=1.33; P=0.011). The RR of THA was also significantly increased in probands (RR=1168; P <3e-08) and in their grandparents (RR=2.06; P=0.01). The RR of KOA was significantly increased in probands with a diagnosis of DDH (RR=20.96; P=2.2e-8) but not in their parents or grandparents. The RR of TKA was also increased in probands alone (RR=57.47; P=1.7e-05). CONCLUSIONS: Parents and grandparents of individuals with diagnosed DDH are significantly more likely to be diagnosed with HOA and undergo THA than members of the general population. These first-degree and second-degree relatives were not at higher risk for KOA or TKA. Given the known familial association of DDH, this association with osteoarthritis of the hip suggests a risk of undiagnosed hip dysplasia in individuals whose families have a high rate of DDH. LEVEL OF EVIDENCE: Level III.

Long-term follow-up of open reduction surgery for developmental dislocation of the hip.

BACKGROUND: We posed 2 questions: what is the long-term result of open reduction surgery in developmental dysplasia of the hip, and is there an age at surgery above which the outcome was too poor to recommend the operation? METHODS: Between 1955 and 1995, 148 patients with 179 dislocated hips had open reduction surgery for developmental dysplasia of the hip (141 anterior and 38 Ludloff medial approaches). We attempted to locate all 148 patients for the follow-up evaluation. RESULTS: Fifty-three patients (36%) with 66 hips (37%) were located and participated in the study. These 66 hips represented 34% of the anterior open reductions and 47% of the Ludloff medial reductions. Twenty-two of the 66 hips had Severin IV or worse outcomes and included 7 with total hip arthroplasties and 2 with hip fusions. Age at surgery was significantly lower for Severin I, II, and III, compared with Severin IV and above (P=0.003, 0.001, 0.003) with outcomes deteriorating substantially after age 3. Approximately half of the hips required further surgery for dysplasia. All hips that sustained osseous necrosis had Severin IV or worse outcomes, and hips that redislocated and required revision surgery only achieved Severin I or II ratings 18% of the time. Nine "normal" hips became dysplastic and 3 had pelvic osteotomies as teenagers. Two other normal hips developed osseous necrosis during treatment of the contralateral hip. CONCLUSIONS: Results deteriorate as the age at surgery increases. Osseous necrosis and redislocation predict a poor functional and radiographic result. The "normal" hip may develop insidious dysplasia and also may be injured during treatment of the involved hip. Above age 3, some patients may not have sufficient acetabular growth to remodel a surgically reduced hip. LEVEL OF EVIDENCE: Level IV--case series.

Measurement of the center edge angle and determination of the Severin classification using digital radiography, computer-assisted measurement tools, and a Severin algorithm: intraobserver and interobserver reliability revisited.

BACKGROUND: Numerous studies underscore the poor intraobserver and interobserver reliability of both the center edge angle (CEA) and the Severin classification using plain film measurements. In this study, experienced observers applied a computer-assisted measurement program to determine the CEA in digital pelvic radiographs of adults who had been previously treated for dysplasia of the hip (DDH). Using a teaching aid/algorithm of the Severin classification, the observers then assigned a Severin rating to these hips. Intraobserver and interobserver errors were then calculated on both the CEA measurements and the Severin classifications. METHODS: Four pediatric orthopaedic surgeons and 1 pediatric radiologist calculated the CEAs using the OrthoView TM planning system and then determined the Severin classification on 41 blinded digital pelvic radiographs. The radiographs were evaluated by each examiner twice, with evaluations separated by 2 months. All examiners reviewed a Severin classification algorithm before making their Severin assignments. The intraobserver and interobserver reliability for both the CEA and the Severin classification were calculated using the interclass correlation coefficients and Cohen and Fleiss κ scores, respectively. RESULTS: The intraobserver and interobserver reliability for CEA measurement was moderate to almost perfect. When we separated the Severin classification into 3 clinically relevant groups of good (Severin I and II), dysplastic (Severin III), and poor (Severin IV and above), our interobserver reliability neared almost perfect. CONCLUSION: The Severin classification is an extremely useful and oft-used radiographic measure for the success of DDH treatment. Our research found digital radiography, computer-aided measurement tools, the use of a Severin algorithm, and separating the Severin classification into 3 clinically relevant groups significantly increased the intraobserver and interobserver reliability of both the CEA and Severin classification. This finding will assist future studies using the CEA and Severin classification in the radiographic assessment of DDH treatment outcomes.

Cerebral palsy: physical activity and sport.

Physical activity and fitness are well recognized as essential to the health of able-bodied people, both young and old. The exact role of athletics and fitness in the lives of people with cerebral palsy is less well defined. In this review we examine the benefits of physical activity and athletics for people of all ages with cerebral palsy. Precautions for safe exercise prescription are discussed. The primary care practitioner will be able to recommend appropriate activities or refer patients to appropriate sources for further evaluation.

Human skin allograft used to treat open wounds after club foot release.

The inversion deformity of club foot is characterized by shortened ligaments and tendons on the medial side of the foot. The condition, when refractory to castings, is treated easily by operative intervention with neutralization of the foot and ankle. Closure of the resulting incision creates tension on the skin that is well tolerated in most children. Correction of severe deformities leaves incisions that will not close primarily, leaving tendons and neurovascular structures exposed on the posteromedial aspect of the foot. Free tissue transfer or spontaneous secondary closure are 2 options that have drawbacks. Application of human skin allograft affords protection to underlying tissue while allowing granulation tissue formation and wound contraction. Subsequent skin autograft and secondary skin contraction and epithelialization provide satisfactory wound closure with normal foot contour and preservation of ankle correction. Complete healing is achieved by the time cast immobilization is discontinued 6 weeks after surgery.

Medial compartment syndrome of the foot: an unusual complication of spine surgery.

STUDY DESIGN: Descriptive case report. OBJECTIVES: To report the case of a child with medial compartment syndrome of the foot following posterior spinal instrumentation and fusion. SUMMARY OF BACKGROUND DATA: No previous study has reported medial compartment syndrome of the foot following spinal surgery. METHODS: A 15-year-old female with progressive idiopathic scoliosis was taken for posterior instrumentation and fusion. The patient had a history of severe postexertional cramping in the feet following athletics. Surgery progressed uneventfully and the patient was continuously monitored with somatosensory-evoked potentials, which showed no changes. In the recovery room, the patient complained of severe cramping in one foot that was similar to her postexertional cramping. This was lessened with massage and ketorolac. Soreness continued in the foot into postoperative day one and then increased overnight. On the morning of postoperative day 2, pressure in the medial compartment was found to be 97 mm Hg and she was taken for fasciotomy, which found necrosis of the abductor hallucis muscle, and all other compartments of the foot were normal. RESULTS: At the 6-month follow-up, the patient is doing well with no known sequelae. CONCLUSION: This was a very rare case of medial compartment syndrome of the foot following spine surgery. We believe that the patient had a predisposition, whether neurologic or vascular, toward cramping in the foot and that this activity was stimulated by the nerve stimulation during the evoked potential monitoring. Although the patient had thoracic epidural analgesia after surgery, it was not felt to have contributed to the development or result of the compartment syndrome. We strongly advocate for checking patients feet and legs during surgery for overactivity and stress the need for a high index of suspicion for compartment syndrome for unexplained pain after surgery.