Patellar-Trochlear Morphology in Pediatric Patients From 2 to 11 Years of Age: A Descriptive Analysis Based on Computed Tomography Scanning.

BACKGROUND: Despite the critical role the trochlea plays in patellofemoral (PF) pathology, the development of the trochlea is poorly understood. The purpose of this study was 2-fold: (1) Describe quantitative osseous and soft tissue anatomy of the patella and trochlea in skeletally immature cadaveric specimens utilizing known measurements used in PF instability, and (2) evaluate additional measurement techniques in the sagittal plane as they relate to PF morphologic development. METHODS: Thirty-one skeletally immature fresh frozen cadaveric knees between the ages of 2 and 11 years old were evaluated using 0.625 mm computed tomography scans. In the axial plane, measurements included condylar height asymmetry, trochlear facet asymmetry, trochlear depth, osseous sulcus angle, cartilaginous sulcus angle, patella sulcus angle, and tibial tubercle-trochlear groove distance. In the sagittal plane, measurements included previously undescribed measurements of trochlear length and condylar height asymmetry which are based on the anterior femoral cortex. RESULTS: Analysis of trochlear morphology using condylar height asymmetry (both axial and sagittal), trochlear facet asymmetry, and trochlear depth and length demonstrated an increase in the size of the medial and lateral trochlea as age increased. There was more variability in the change of size of the medial trochlea (height, length, and facet length) than the lateral trochlea. The osseous sulcus angle, cartilaginous sulcus angle, and patella sulcus angle decreased (became deeper) with age until after 8 years and then plateaued. CONCLUSIONS: This cadaveric analysis demonstrated that there is an increase in the medial and lateral trochlear height as age increased by all measurements analyzed. The findings also demonstrate that the shape of the patella and trochlea change concurrently, which suggests that there may be interplay between the 2 during development. These new sagittal measurement techniques evaluating the medial, central, and lateral trochlear height and length with respect to age may help guide clinicians when investigating patellar instability in skeletally immature patients. LEVELS OF EVIDENCE: Level IV.

Quadriceps Tendon Graft Anatomy in the Skeletally Immature Patient.

BACKGROUND: The quadriceps tendon (QT) is increasingly considered for primary and revision anterior cruciate ligament reconstruction in skeletally immature patients, as it may be harvested as a purely soft tissue graft with considerable tissue volume. Because of distinct rectus tendon (RT) separation from the QT complex, the potential for RT retraction exists and could lead to QT weakness after QT graft harvest. PURPOSE: To describe the anatomy of the pediatric QT and clarify decussation of the RT and QT to avoid the risk of delayed RT retraction and QT weakness after QT graft harvest. STUDY DESIGN: Descriptive epidemiology study. METHODS: Nine cadaveric knee specimens (aged 4-11 years) underwent gross dissection. Coronal-plane width and depth of the QT were measured at intervals proximal to the superior pole of the patella at distances of 0.0, 0.5, 1.0, and 1.5 times the length of the patella. The distance was measured from the superior patellar pole to the point of RT separation from the remainder of the deeper/posterior QT. RESULTS: The median patellar length was 28 mm (interquartile range, 26-37 mm). The coronal-plane width of the QT was larger superficially/anteriorly when closest to the patella but wider when measured deeper/posteriorly as the tendon extended proximally. The median distance between the superior pole of the patella and RT separation from the QT was 0.95 times the patellar length. The distance to widening of the deeper/posterior aspect of the QT was 1.14 times the patellar length proximal to the patella. CONCLUSION: The RT begins a distinct separation from the QT above the superior pole of the patella at a median of 0.95 times the patellar length in skeletally immature specimens. The deeper/posterior aspect of the QT begins to increase in coronal-plane width proximally after a distance of 1.14 times the patellar length above the knee, while the superficial/anterior aspect of the tendon continues to narrow. Awareness of the separation of the RT from the QT, and the coronal-plane width variation aspects of the QT proximally, is important for surgeons utilizing the QT as a graft to avoid inadvertent release of the RT from the rest of the QT complex.

The Position of the Popliteal Artery and Peroneal Nerve Relative to the Menisci in Children: A Cadaveric Study.

BACKGROUND: Meniscal injury in skeletally immature patients is increasingly reported. During meniscal repair, all-inside devices may protrude beyond the posterior limits of the meniscus, putting the neurovascular structures at risk. PURPOSE: The purposes of this study were (1) to examine the relationship between the popliteal artery and the posterolateral and posteromedial aspects of the menisci, (2) to examine the relationship of the peroneal nerve to the posterolateral meniscus, and (3) to develop recommendations for avoiding neurovascular injury during posterior meniscal repair in pediatric patients. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 26 skeletally immature knee cadaveric specimens (7 females and 19 males) were included. Specimens were divided into age groups: 2-4, 5-8, and 9-11 years. The most posterior extent of the lateral and medial menisci was identified via sagittal and axial views on computed tomography (CT) scans. The shortest distance from the most posterior aspect of the lateral and medial menisci to the popliteal artery and the shortest distance from the posterior aspect of the lateral menisci to the anterior rim of the peroneal nerve were measured, and 3-dimensional models of representative specimens were re-created through use of CT scans. RESULTS: For the age groups 2-4, 5-8, and 9-11 years, the mean minimum distance from the posterolateral meniscus to the popliteal artery was 5.2, 6.7, and 8.2 mm, respectively, and the mean minimum distance from the posteromedial meniscus to the popliteal artery was 12.7, 15.4, and 20.3 mm, respectively. In all groups, the distance between the posteromedial meniscus and the popliteal artery was greater than that between the posterolateral meniscus and the popliteal artery. The mean distance from the peroneal nerve to the lateral meniscus was 13.3, 15.0, and 17.9 mm for the respective groups. CONCLUSION: Many all-inside meniscal repair devices have sharp tips that penetrate posterior to the meniscus and capsule. This study demonstrated that the distance between the posterior meniscus and popliteal artery is relatively small in pediatric patients, especially for the lateral meniscus region. CLINICAL RELEVANCE: Because of the higher potential for meniscal healing, meniscal repair is more likely to be performed in pediatric patients. The data in this study regarding the proximity of the lateral meniscus and neurovascular structures may be used to guide safe surgical repair of posterior meniscal tears during the use of all-inside meniscal repair devices in these patients.

Proximity of the neurovascular structures during all-inside lateral meniscal repair in children: a cadaveric study.

PURPOSE: Meniscal repair has become increasingly common in a pediatric and adolescent population. All-inside repair techniques are utilized more often given their ease of insertion and decreased operative time required. However, there are possible risks including damage to adjacent neurovascular structures. The purpose of this study to was examine the proximity of the neurovascular structures during lateral meniscus repairs in pediatric specimens simulating a worst-case scenario. METHODS: Ten pediatric cadaveric knees (age 4-11) were utilized and simulated lateral meniscal repair through the posterior horn of the lateral meniscus and both medial and lateral to the popliteal hiatus through the body of the lateral meniscus was performed with an all-inside meniscal repair device. The distance to the popliteal artery or peroneal nerve was measured. RESULTS: During posterior horn repair, the average distance from the all-inside device to the popliteal artery was 1.9 mm ± 1.1 mm. There was penetration of the artery in one specimen. During repair on the medial side of popliteal hiatus, the average distance from the all-inside device to the peroneal nerve was 3.2 mm ± 2.0 mm. During repair on the lateral side of popliteal hiatus, the average distance from the all-inside device to the peroneal nerve was 12.4 mm ± 3.7 mm. CONCLUSIONS: This study demonstrates that the proximity of the neurovascular structures to the lateral meniscus in children is extremely close and at high risk during meniscal repair with all-inside devices. This study gives important data for the proximity of these structures during these repair techniques. LEVEL OF EVIDENCE: Level 5 Cadaveric Study.

Osteochondritis Dissecans in the Skeletally Immature Knee.

Osteochondritis dissecans of the knee, which results in knee symptoms and activity-related pain, is a condition that commonly affects young individuals. The etiology of osteochondritis dissecans remains unclear; however, genetic and endocrine factors, ischemia, inflammation, repetitive microtrauma, and spontaneous osteonecrosis have been suggested as causes of osteochondritis dissecans. Skeletally immature patients with a stable osteochondritis dissecans lesion typically have minimal clinical symptoms and, if treated nonsurgically, experience a high rate of healing. Surgical treatment should be considered for pediatric patients with a stable lesion that does not heal and pediatric patients who have an unstable lesion with articular cartilage defects. Surgical treatment also should be considered for patients who have nearly closed or closed physes, regardless of age. Skeletally immature patients with a stable lesion can be treated via subchondral bone drilling. Advanced lesions that are salvageable may require management via more complex procedures, including fixation with or without bone grafting and cartilage reconstruction procedures, to restore the osteochondral defect.

What's New in Pediatric Upper Extremity Sports Injuries?

BACKGROUND: Sports injuries are common in pediatric and adolescent patients and the evaluation and treatment of these injuries continues to evolve. The purpose of this review is to provide a comprehensive appraisal of the most recent literature, highlighting updates on sports-related upper extremity injuries in pediatric patients. METHODS: An electronic search of the PubMed, EMBASE, and Google Scholar databases was performed for keywords related to pediatric overhead athletes, osteochondritis dissecans (OCD) of the capitellum, medial epicondyle fractures, shoulder instability, and clavicle fractures. Search results were filtered by publication date to yield articles published electronically or in print on or after January 1, 2013 to May 30, 2017. Papers were selected based on expert opinion and consensus by the authors and included if deemed to have contributed important findings to the above topics. RESULTS: A total of 51 articles were deemed to have contributed significant findings to the literature: 11 overhead athlete, 9 OCD of the capitellum, 6 medial epicondyle fractures, 17 shoulder instability, and 8 clavicle fractures. The level of evidence for most studies was either Level III or IV. CONCLUSIONS: Overuse and traumatic conditions of the pediatric elbow including UCL tear, capitellar OCD, and medial epicondyle fractures represent a significant portion of injuries in the overhead athlete. Research in the prevention and treatment of primary and recurrent shoulder instability in young athletes continues to evolve. The operative treatment of clavicle fractures in adolescents has been increasing without a commensurate increase in the level of evidence supporting such treatment. Advances have been made in the treatment of sports-related upper extremity injuries in pediatric patients, however, high-level, comparative outcomes research in many areas is lacking and this review may help inform topics for future study. LEVEL OF EVIDENCE: Level IV-Literature review.

Incidence of Meniscal Entrapment and Associated Knee Injuries in Tibial Spine Avulsions.

BACKGROUND: Tibial spine avulsions (TSA) have historically been treated as isolated injuries. Data on associated injuries are limited with existing literature reporting wide ranging incidences. The purpose of this multicenter study was to (1) describe the incidence of meniscal entrapment and associated knee injuries in TSA and to (2) compare surgical and magnetic resonance image (MRI) findings for these injuries. Our hypothesis is that tibial spine injuries are not usually isolated injuries, and other meniscal, ligament, and cartilage injuries may be present. METHODS: MRI and surgical reports for patients with a diagnosis of a tibial spine fracture were retrospectively reviewed. Type of fracture was recorded as noted in the reports along with concomitant meniscal entrapment and osteochondral, ligamentous, and meniscal injury. Images and reports were reviewed by an orthopaedic surgeon at each respective institution. RESULTS: A total of 163 patients were included in this study. MRI was done for 77 patients and surgery was performed in 144 cases. Meniscal entrapment was found in 39.9% of all patients. MRI diagnosed meniscus, osteochondral, and non-anterior cruciate ligament ligamentous injury was found in 31.2%, 68.8%, and 32.4% of cases, respectively. Surgically diagnosed meniscus, chondral, and non-anterior cruciate ligament ligamentous injury was found in 34.7%, 33.3%, and 5.6% of patients, respectively. CONCLUSIONS: TSA fractures are associated with significant risk for concomitant knee injuries including meniscal tear, bone contusion, and chondral injury. Incidence of meniscal entrapment found during surgery was high, in spite of low incidence of positive findings by MRI. LEVEL OF EVIDENCE: Level IV-retrospective case series.

What's New in Pediatric Sports Conditions of the Knee?

BACKGROUND: Sports injuries are common in pediatric and adolescent patients and the evaluation and treatment of these injuries continues to evolve. The purpose of this review is to provide a comprehensive appraisal of the literature, highlighting recent updates on sports-related knee injuries in the pediatric athlete. We specifically examined literature on tibial spine fractures, osteochondritis dissecans (OCD) of the knee, and patellar instability. Because of the volume of literature on the subject, pediatric, and adolescent anterior cruciate ligament injuries were not included in this review. METHODS: An electronic search of the PubMed, EMBASE, and Google Scholar databases was performed for keywords related to pediatric: tibial spine fractures, patellar instability, and osteochondritis dissecans (OCD). Search results were filtered by publication date to yield articles published electronically or in print on or after January 1, 2013. Papers were selected based on expert opinion and consensus by the authors and included if deemed to have contributed important findings to the above topics. RESULTS: A total of 31 articles were deemed to have contributed significant findings to the literature: 5 tibial spine, 17 patellar instability, and 9 OCD. The level of evidence for most studies was either level III or IV. CONCLUSIONS: The optimal treatment for tibial spine fractures remains controversial. The evaluation of risk factors for recurrent patellar instability is important in determining the optimal treatment strategy following first-time patellar dislocation. Future multicenter studies on pediatric OCD have the potential to further understanding of this difficult problem. High-level, comparative outcomes research on a variety of pediatric sports related injuries is lacking and this review may help inform topics for future study. LEVEL OF EVIDENCE: Level IV-literature review.

Variation in the Medial Patellofemoral Ligament Origin in the Skeletally Immature Knee: An Anatomic Study.

BACKGROUND: The medial patellofemoral ligament (MPFL) is frequently reconstructed to treat recurrent patellar instability. The femoral origin of the MPFL is well described in adults but not in the skeletally immature knee. PURPOSE: To identify a radiographic landmark for the femoral MPFL attachment in the skeletally immature knee and study its relationship to the distal femoral physis. STUDY DESIGN: Descriptive laboratory study. METHODS: Thirty-six cadaveric specimens between 2 and 11 years old were dissected and examined (29 male and 7 female). Metallic markers were placed at the proximal and distal borders of the MPFL femoral origin footprint. Computed tomography scans with 0.625-mm slices in the axial, coronal, and sagittal planes were used to measure the maximum ossified height and ossified depth. The measurements were used to describe the position of the midpoint MPFL attachment with respect to the posterior-anterior and distal-proximal dimensions of the femoral condyle on the sagittal view and to describe the distance from the physis to the femoral origin of the MPFL. RESULTS: In 23 of 36 specimens, the femoral origin of the MPFL was distal to the physis. Thirteen of the 36 specimens had an MPFL origin at or proximal to the physis, with a more proximal MPFL origin consistently seen in older specimens. The distance of the MPFL origin to the physis ranged from 15.1 mm distal to the physis to 8.3 mm proximal to the physis. The mean midpoint of the MPFL femoral origin was located 3.0 ± 5.5 mm distal to the physis for all specimens. For specimens aged <7 years, the mean MPFL origin was 4.7 mm distal to the physis, and for specimens aged ≥7 years, the mean MPFL origin was 0.8 mm proximal to the femoral physis. The MPFL origin was more proximal and anterior for those aged ≥7 years and more distal and posterior for those aged <7 years. CONCLUSION: Surgical reconstruction of the MPFL is a common treatment to restore patellar stability. There appears to be significant variability in the origin of the MPFL in skeletally immature specimens. This study demonstrated that the MPFL origin was more proximal and anterior with respect to the physis in the older age group. The MPFL origin footprint may be customized for different age groups. CLINICAL RELEVANCE: This information shows anatomic variation of the MPFL origin with age, with older specimens having a footprint that was more proximal and anterior than younger specimens. Customization of the surgical technique might be considered based on patient age.