Abstract: Anterior cruciate ligament reconstruction (ACLR) remains one of the most commonly performed orthopaedic surgeries in adolescents and young adults. However, selection of the optimal graft for the individual patient remains controversial, considering multiple graft options, subtle technique differences, and wide-ranging bodies of evidence for each graft option in largely adult populations. However, multiple epidemiologic studies clearly demonstrate adolescents as the most greatly affected age-based sub-population, with the highest rates of re-tear and global morbidity, due to psychological and physical effects of long absences from athletic activity. Nevertheless, methodologically rigorous comparative studies specific to the adolescent athlete are largely absent from the literature. The purpose of the current study is to therefore investigate the outcomes of ACLR in adolescents receiving either patellar tendon/bone-tendon-bone (BTB) autograft (ACLR-BTB) or hamstring tendon autograft (ACLR-HS), using retrospective propensity score matching techniques to generate comparable cohorts. Methods: The study was designed as a retrospective chart review, with collection of cross-sectional data from a single pediatric tertiary care center over a thirteen year period (2003-2015). An initial cohort of patients, aged 13-19 years at time of primary ACLR-BTB or primary ACLR-HS by one of 5 surgeons, was identified through a comprehensive electronic medical record database query. Propensity score matching of ACLR-BTB and ACLR-HS subjects through a logistic regression model, with caliper restriction of 0.1 standard deviations, was then applied, based upon specific baseline characteristics that are frequently used by some surgeons to guide graft selection: age, sex, and body mass index (BMI). The resultant cohort of patients obtained a 1:2 (ACLR-BTB: ACLR-HS, 83 patients:186 patients) match. A chart review was performed to identify patient demographics, surgical data, and post-operative outcomes including graft rupture/re-tear and length of clinical follow-up. Patients were additionally contacted to obtain longer term sport participation and re-injury data that may have been investigated or addressed at outside institutions, as well as to obtain functional outcomes using region-specific questionnaires (Pedi-IKDC and HSS-Pedi FABS), which are validated for both this younger population and adult populations. Due to previous literature-based reports on greater anterior knee pain following ACLR-BTB, compared to ACL-HS, scores from the questions specific to knee pain or kneeling pain were extracted from the Pedi-IKDC results and analyzed to assess the potential influence of anterior knee pain on overall scores within this adolescent population. Results: At time of ACLR, the mean age and BMI of the matched ACLR-BTB patients were 17.1 years (sd: +/-1.14 years) and 25.8 (sd: +/-5.04), compared to 16.9 years (sd: +/- 1.38, p: 0.18) and 24.9 (sd: +/- 5.01, p: 0.18) for matched ACLR-HS patients, with similar male preponderance (ACLR-BTB: 77%, ACLR-HS: 72%, p: 0.47) and mean length of follow-up (ACLR-BTB: 42.9 months; ACLR-HS: 43.3 months). While mean Pedi-IKDC scores were slightly higher in the ACLR-BTB group (88.8; sd: +/-10.2, range: 56.5-100) than the ACLR-HS group (85.2; sd: +/- 16.1, range: 23.9-100), this difference was not statistically different (p: 0.50). When scores on questions regarding knee pain and kneeling difficulty were analyzed, no differences were seen between graft cohorts (ACLR-BTB: median knee pain score: 4, ACLR-HS: 4 p: 0.73; ACLR-BTB median kneeling difficulty score: 4, ACLR-HS: 4, p: 0.21). Activity level, based on the HSS-Pedi FABS score, was also similar (ACLR-BTB: 16, range: 3-29 vs. ACLR-HS: 17, range: 0-30; p: 0.96). Rates of ACL graft re-tear were not significantly different between groups, both when calculated based all possible follow-up methods (ACLR-BTB: 11%, ACLR-HS: 11%, p: 0.91), or when those patients responding to long-term follow up questionnaires were isolated (ACLR-BTB: 15%, ACLR-HS: 16%, p: 0.85). Conclusion/Significance: Despite previous studies, including large, multi-country registry-based analyses, demonstrating lower re-tear rates following ACLR-BTB than ACLR-HS, the current study, focused exclusively on adolescent cohorts matched for age, sex, and BMI, showed no difference in graft re-tear rates between the two cohorts at medium-term follow-up. Moreover, activity scores and functional knee outcome scores appear to be equivalent between these younger graft-based populations. In contrast to previous studies associating BTB autograft with greater long term anterior knee pain, adolescents appear to have equal degrees of knee pain or kneeling pain, regardless of graft choice, which may stem from greater healing and biologic remodeling capacity at graft harvest sites than adults or more modern techniques of patellar bone grafting and paratenon closure. Given the consistently high adolescent ACL re-tear rates in this and other studies, continued focus on ACL prevention programs and optimizing the timing and safety of return to play remains critical.

Abstract: The purpose of this study is to compare the re-tear rates and medium-term functional outcomes in matched cohorts of adolescent athletes who underwent primary anterior cruciate ligament reconstruction (ACLR) with patellar tendon/bone-tendon-bone autograft (BTB) versus hamstring tendon autograft (HS). Methods: An initial cohort of 731 patients, aged 13-19 years, who underwent ACLR-BTB or ACLR-HS between 2003-2015 at a pediatric tertiary care hospital by one of 5 surgeons, was identified through a comprehensive electronic medical record database query. Propensity score matching was performed through a logistic regression model, based on characteristics frequently used by some surgeons to guide graft selection: age, sex, and body mass index (BMI). The resultant cohort of 269 patients allowed for a 1:2 (BTB: HS, 83:186) match. A chart review was performed to identify patient demographics, surgical data, and post-operative outcomes, including ACL re-tear and length of clinical follow-up. Patients were additionally contacted to obtain longer term sport participation and re-injury data that may have been investigated or addressed at outside institutions, as well as to obtain patient reported outcomes (PRO) using validated knee function and activity questionnaires (Pedi-IKDC and HSS-Pedi FABS). Individual questions from the Pedi-IKDC that related to anterior knee pain or kneeling pain were specifically investigated to assess the potential effect of these factors, commonly cited aspects of donor site morbidity associated with BTB grafts, on overall scores within this adolescent population. Results: No significant differences were seen in demographic and clinical characteristics of the two matched graft-based cohorts (overall mean clinical follow-up: 54 months), as listed in Table 1. In the sub-population providing PROs (52% response rate, mean PRO follow up: 81 months), no significant differences were seen in activity level, median Pedi-IKDC scores, or knee pain. BTB patients demonstrated superior scores regarding ability to kneel than HS patients. Rates of ACL graft re-tear were not significantly different between groups, both when calculated based on all possible follow-up methods (ACLR-BTB: 11%; ACLR-HS: 12%; p: 0.72), or amongst patients responding to long-term follow up. Conclusion: Despite previous studies, including large, multi-country registry-based analyses, demonstrating lower re-tear rates following ACLR-BTB than ACLR-HS, the current study, focused exclusively on adolescent cohorts matched for age, sex, and BMI, showed no difference in graft re-tear rates between the two cohorts at medium-term follow-up. Moreover, activity scores and overall functional knee outcome scores appear to be equivalent between these younger graft-based populations, with no suggestion of increased donor site morbidity with BTB autograft, as it relates to knee pain or kneeling ability. For skeletally mature adolescents, graft choice may not influence outcome following ACL reconstruction. Consistent with previous studies, the current study reveals relatively high ACL re-tear rates in adolescents, the sub-population most affected by this common injury. [Table: see text]

Abstract: Despite several well-described operative techniques, the optimal management of anterior cruciate ligament (ACL) injuries in pediatric patients remains unclear. The goal of this study was to identify preferred techniques in skeletally immature patients of various ages and analyze differences in operative strategy based on surgeon and practice demographics. Methods: An electronic survey was administered to members of the Pediatric Research in Sports Medicine society, a cohort of experienced surgeons who perform a high volume of pediatric ACL reconstructions. The survey presented a scenario of a patient who had a physical exam and imaging consistent with an acute, isolated ACL tear. The respondent was asked to select their preferred reconstruction technique for females and males at consecutive skeletal ages from 8 to 15 years. Surgeon and practice demographic information was recorded. Univariate analysis was followed by stepwise multinominal logistic regression to control for confounders. Results: Eighty-eight of 103 surgeons (85%) responded to the survey, the majority of whom (68%) performed more than 25 pediatric ACL reconstructions annually. The greatest variation in technique was from ages 11 to 13 in females and 11 to 14 in males. The modified MacIntosh was the most frequently utilized from ages 8 to 10. An all-epiphyseal technique was preferred over a broader age range in males than females, with peak utilization at age 11 in both. A partial trans-physeal (hybrid) technique was preferred in slightly older patients, with peak utilization at age 12 in females and 13 in males. The trans-physeal technique was most widely used at age 13 and up in females and 14 and up in males. The impact of fellowship training on technique preference was statistically significant for males ages 11-13 and females 11 and 12 (p 〈 0.05 for all). Surgeons with pediatric orthopaedic training tended to prefer an all-epiphyseal reconstruction, while those with both pediatric and sports training preferred the modified MacIntosh. Conclusions: The preferred ACL reconstruction technique for skeletally immature patients varied considerably, especially in the 11-13 year-old age range, highlighting a lack of consensus among orthopedic surgeons for the optimal ACL reconstruction strategy in skeletally immature patients. Surgeon’s fellowship training was significantly associated with their preferred surgical technique.

Abstract: Imaging characteristics of osteochondritis dissecans (OCD) lesions quantified by magnetic resonance imaging (MRI) are often used to inform treatment and prognosis. However, the interrater reliability of clinician-driven MRI-based assessment of OCD lesions is not well documented. Purpose: To determine the interrater reliability of several historical and novel MRI-derived characteristics of OCD of the knee in children. Study Design: Cohort study (diagnosis); Level of evidence, 3 Methods: A total of 42 OCD lesions were evaluated by 10 fellowship-trained orthopaedic surgeons using 31 different MRI characteristics, characterizing lesion size and location, condylar size, cartilage status, the interface between parent and progeny bone, and features of both the parent and the progeny bone. Interrater reliability was determined via intraclass correlation coefficients (ICCs) with 2-way random modeling, Fleiss kappa, or Krippendorff alpha as appropriate for each variable. Results: Raters were reliable when the lesion was measured in the coronal plane (ICC, 0.77). Almost perfect agreement was achieved for condylar size (ICC, 0.93), substantial agreement for physeal patency (ICC, 0.79), and moderate agreement for joint effusion (ICC, 0.56) and cartilage status (ICC, 0.50). Overall, raters showed significant variability regarding interface characteristics (ICC, 0.25), progeny (ICC range, 0.03 to 0.62), and parent bone measurements and qualities (ICC range, –0.02 to 0.65), with reliability being moderate at best for these measurements. Conclusion: This multicenter study determined the interrater reliability of MRI characteristics of OCD lesions in children. Although several measurements provided acceptable reliability, many MRI features of OCD that inform treatment decisions were unreliable. Further work will be needed to refine the unreliable characteristics and to assess the ability of those reliable characteristics to predict clinical lesion instability and prognosis.

Abstract: Growth disturbance is an uncommon but potentially serious complication after anterior cruciate ligament (ACL) reconstruction in skeletally immature patients. Purpose: To describe how the pediatric ACL literature has assessed preoperative skeletal maturity and the amount of growth remaining and to comprehensively review the incidence, reporting, and monitoring of postoperative growth disturbance. Study Design: Systematic review; Level of evidence, 4. Methods: This review included studies reporting original research of clinical outcomes of skeletally immature patients after ACL reconstruction. Patient characteristics, surgical techniques, preoperative assessments of skeletal maturity or growth remaining, and postoperative assessments of growth disturbances were extracted. Results: A total of 100 studies met inclusion criteria. All studies reported chronological age, and 28 studies (28%) assessed skeletal age. A total of 44 studies (44%) used Tanner staging, and 12 studies (12%) obtained standing hip-to-ankle radiographs preoperatively. In total, 42 patients (2.1%) demonstrated a leg length discrepancy (LLD) 〉 10 mm postoperatively, including 9 patients (0.5%) with LLD 〉 20 mm; furthermore, 11 patients (0.6%) with LLD underwent growth modulation. Shortening was the most common deformity overall, but overgrowth was reported more frequently in patients who had undergone all-epiphyseal techniques. Most LLDs involved the femur (83%). A total of 26 patients (1.3%) demonstrated a postoperative angular deformity ≥5°, and 9 of these patients underwent growth modulation. The most common deformities were femoral valgus (41%), tibial recurvatum (33%), and tibial varus (22%). Although standing hip-to-ankle radiographs were the most common radiographic assessment of growth disturbance, most studies inadequately reported the clinical and radiographic methods of assessment for growth disturbance. Additionally, only 35% of studies explicitly followed patients to skeletal maturity. Conclusion: This systematic review described significant variability in the reporting and monitoring of growth-related complications after ACL reconstruction in skeletally immature patients. The incidence of LLD and angular deformity appeared to be low, but the quality of research was not comprehensive enough for accurate assessment. Registration: CRD42019136059 (PROSPERO)

Abstract: Osteochondritis dissecans (OCD) occurs most commonly in the knees of young individuals. This condition is known to cause pain and discomfort in the knee and can lead to disability and early knee osteoarthritis. The cause is not well understood, and treatment plans are not well delineated. The Research in Osteochondritis Dissecans of the Knee (ROCK) group established a multicenter, prospective cohort to better understand this disease. Purpose: To provide a baseline report of the ROCK multicenter prospective cohort and present a descriptive analysis of baseline data for patient characteristics, lesion characteristics, and clinical findings of the first 1000 cases enrolled into the prospective cohort. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients were recruited from centers throughout the United States. Baseline data were obtained for patient characteristics, sports participation, patient-reported measures of functional capabilities and limitations, physical examination, diagnostic imaging results, and initial treatment plan. Descriptive statistics were completed for all outcomes of interest. Results: As of November 2020, a total of 27 orthopaedic surgeons from 17 institutions had enrolled 1004 knees with OCD, representing 903 patients (68.9% males; median age, 13.1 years; range, 6.3-25.4 years), into the prospective cohort. Lesions were located on the medial femoral condyle (66.2%), lateral femoral condyle (18.1%), trochlea (9.5%), patella (6.0%), and tibial plateau (0.2%). Most cases involved multisport athletes (68.1%), with the most common primary sport being basketball for males (27.3% of cases) and soccer for females (27.6% of cases). The median Pediatric International Knee Documentation Committee (Pedi-IKCD) score was 59.9 (IQR, 45.6-73.9), and the median Pediatric Functional Activity Brief Scale (Pedi-FABS) score was 21.0 (IQR, 5.0-28.0). Initial treatments were surgical intervention (55.4%) and activity restriction (44.0%). When surgery was performed, surgeons deemed the lesion to be stable at intraoperative assessment in 48.1% of cases. Conclusion: The multicenter ROCK group has been able to enroll the largest knee OCD cohort to date. This information is being used to further understand the pathology of OCD, including its cause, associated comorbidities, and initial presentation and symptoms. The cohort having been established is now being followed longitudinally to better define and elucidate the best treatment algorithms based on these presenting signs and symptoms.

Abstract: Radiographic measurements of limb alignment in skeletally immature patients with anterior cruciate ligament (ACL) tears are frequently used for surgical decision-making, preoperative planning, and postoperative monitoring of skeletal growth. However, the interrater and intrarater reliability of these radiographic characteristics in this patient population is not well documented. Hypothesis: Excellent reliability across 4 raters will be demonstrated for all digital measures of length, coronal plane joint orientation angles, mechanical axis, and tibial slope in skeletally immature patients with ACL tears. Study Design: Cohort study (diagnosis). Methods: Three fellowship-trained orthopaedic surgeons and 1 medical student performed 2 rounds of radiographic measurements on digital imaging (lateral knee radiographs and long-leg radiographs) of skeletally immature patients with ACL tears. Intrarater and interrater reliability for continuous radiographic measurements was assessed with intraclass correlation coefficients (ICCs) across 4 raters with 95% CIs for affected and unaffected side measurements. Interrater reliability analysis used an ICC (2, 4) structure and intrarater reliability analysis used an ICC (2, 1) structure. A weighted kappa coefficient was calculated for ordinal variables along with 95% CIs for both interrater and intrarater reliability. Agreement statistic interpretations are based on scales described by Fleiss, and Cicchetti and Sparrow: 〈 0.40, poor; 0.40 to 0.59, fair; 0.60 to 0.74, good; and 〉 0.74, excellent. Results: Radiographs from a convenience sample of 43 patients were included. Intrarater reliability was excellent for nearly all measurements and raters. Interrater reliability was also excellent for nearly all reads for all measurements. Conclusion: Radiographic reliability of long-leg radiographs and lateral knee x-rays in skeletally immature children with ACL tears is excellent across nearly all measures and raters and can be obtained and interpreted as reliable and reproducible means to measure limb length and alignment. Level of Evidence: Level III.

Abstract: While traditional biological principles have suggested that fragments consisting of cartilage alone cannot be reaffixed to bone with expectable long-term healing, case reports of successful healing after fixation in younger patients indicate that this concept remains incompletely explored. Purpose: To evaluate the presenting features, techniques, healing rates, and clinical and radiological results in a cohort of pediatric and adolescent athletes who underwent fixation of traumatic chondral-only fragments in the knee. Study Design: Case series; Level of evidence, 4. Methods: Patient registries at 2 tertiary care children’s hospitals were reviewed to identify patients ≤18 years old who underwent fixation of a “chondral-only” fragment in the knee, defined as the inability to visualize the fragment on injury radiographs or discern bone on the articular portion of a fragment intraoperatively. The mechanism of injury, fragment features, fixation technique, and postoperative clinical course, including timing of sports clearance, healing on postoperative magnetic resonance imaging (MRI), and any complications or reoperations, were assessed. Results: Fifteen patients with a median age at surgery of 12.7 years (interquartile range [IQR], 11.7-14.2 years) and median follow-up of 12.0 months (IQR, 6.0-19.2 months) were analyzed. All patients sustained an acute knee injury before surgery. The injured sites, as assessed on MRI, were the patella (n = 6), trochlea (n = 5), and lateral femoral condyle (n = 4). The median fragment surface area was 492.0 mm 2 (IQR, 400.0-787.5 mm 2 ). Fixation with bioabsorbable implants was performed in all patients at a median of 1.6 weeks (IQR, 1.0-2.6 weeks) after the injury. One patient (7%) sustained a fall 8 weeks postoperatively, requiring secondary surgery for excision of a dislodged fragment, and 1 patient (7%) underwent unrelated patellar stabilization surgery 3.4 years postoperatively, at which time the fragment was found to be stable. MRI was performed in 9 of 14 patients with retained fragments (median, 12.0 months postoperatively), with 5 patients (56%) showing restoration of the cartilage contour and the resolution of subchondral edema; 2 patients showed thinning but intact cartilage, 1 had cartilage thickening, and 1 had subchondral edema, fissuring, and cystic changes. The median time to return to sports for all 15 patients was 26.0 weeks (IQR, 22.8-40.9 weeks), including 2 patients who required second surgery and returned to sports at 26.1 and 191.1 weeks. Conclusion: Fixation of traumatic chondral-only fragments using bioabsorbable implants may result in successful short-term healing in the majority of pediatric and adolescent athletes.

Abstract: Tibial spine fractures most commonly occur in children aged 8 to 14 years and are occasionally seen in adults. Although the annual incidence is 3 per 100,000 children, they account for 2-5% of pediatric knee injuries with effusions and are associated with substantial complications including ACL deficiency and arthrofibrosis. The rise in competitive youth sports has brought increased public attention to this injury. Meyers and McKeever Type II fractures are displaced anteriorly with an intact posterior hinge. This specific subtype of pediatric tibial spine fractures has controversy in the literature whether they should be treated non-operatively or operatively. The purpose of this study was to identify assess for variability amongst pediatric orthopaedic surgeons when treating pediatric type II tibial spine fractures. Methods: A discrete choice experiment was conducted to determine the patient and injury attributes that influence the management of type II pediatric tibial spine fractures by pediatric orthopaedic surgeons. A convenience sample of 14 pediatric orthopaedic surgeons reviewed 40 case vignettes (Figure 1) that included radiographs displaying fractures with varying degrees of displacement (range: 2.5 – 6.0 mm) and a brief description on the patient’s sex, age (8-17), mechanism of injury (fall, collision, hypertension, twist), and predominant sport (swimming, football, basketball, nonathlete). Surgeons were asked whether they would treat the fracture operatively or non-operatively. Physes were blinded. A mixed effects model was used to determine the patient attributes most likely to influence the surgeon’s decision for operative treatment of a tibial spine fracture. In addition, the association between surgeon propensity for operative treatment based on surgeon training, years in practice, and risk-taking behavior based on the Jackson Personality Inventory subscale was assessed. A receiver operating characteristic curve was used to determine probability of surgical treatment based on the degree of fracture displacement. Results: Surgeon demographics are summarized in Table 1. Overall, the 14 respondents selected operative treatment in 75% of the presented cases. The degree of fracture displacement was the only patient attribute that was significantly associated with treatment choice (p 〈 0.001). Surgeons were 29% more likely to treat the fracture operatively with each additional millimeter of displacement. The probability of opting for surgical treatment exceeded 50% when the fracture had 3.5 or more millimeters of displacement. Significant variation in surgeon’s propensity for operative treatment of this fracture was observed (p=0.01). Nine of the 14 surgeons demonstrated a significant propensity for operative treatment of this injury. Surgeon training, years in practice, and risk-taking scores were not associated with the respondent’s preference for surgical treatment. Conclusions / Significance: There is substantial variation among pediatric orthopaedic surgeons when treating type II tibial spine fractures. The decision to operate is significantly based on the degree of fracture displacement. However, there is no standardization regarding how to treat type II tibial spine fractures and therefore better treatment algorithms are needed to optimize patient outcomes. Learning about the current treatment preferences among surgeons given different patient factors can highlight current variation in practice patterns and direct efforts toward promoting the most optimal treatment strategies. [Table: see text]