Pediatric meniscus morphology varies with age: a cadaveric study.

PURPOSE: In adolescent patients, meniscal tear injury can occur either in isolation (e.g., discoid lateral meniscus tears) or in association with other traumatic injuries including tibial eminence fracture or ACL tear. Damage to meniscal integrity has been shown to increase contact pressure in articular cartilage, increasing risk of early onset osteoarthritis. In symptomatic patients failing conservative management, surgical intervention via meniscus repair or meniscus transplant is indicated. The purpose of this study was to evaluate the radial dimensions of pediatric menisci throughout development. The hypothesis was that the average radial meniscus dimensions will increase as specimen age increases, and mean medial and lateral region measurements will increase at a linear rate. METHODS: Seventy-eight skeletally immature knee cadaver specimens under age 12 years were included in this study. The meniscal specimens were photographed in the axial view with ruler in the plane of the tibial plateau and analyzed using computer-aided design (CAD) software (Autodesk Fusion 360). Measurements were taken from inner to outer meniscus rims at five 45 degree intervals using the clockface as a reference (12:00, 1:30, 3:00, 4:30, 6:00), and total area of meniscus and tibial plateau was recorded. Generalized linear models were used to evaluate the associations of radial width measurements with age, tibial coverage, and lateral vs. medial meniscus widths. RESULTS: All radial width measurements increased significantly with specimen age (p ≤ 0.002), and all lateral-medial meniscal widths increased (p < 0.001). The anterior zones of the meniscus were found to increase at the slowest rate compared to other regions. Tibial plateau coverage was found to not significantly vary with age. CONCLUSIONS: Meniscus radial width and lateral-medial meniscus width are related to age. The anterior width of the meniscus varied least with age. Improved anatomic understanding may help surgeons more effectively plan for meniscus repair, discoid resection/saucerization/repair, and also support appropriate selection of meniscus allograft for transplantation.

Quantifying the Relationship Between the Medial Quadriceps Tendon-Femoral Ligament and Patellar Borders: A Pediatric Cadaveric Study.

BACKGROUND: The medial patellofemoral complex (MPFC) is a structure composed of the medial quadriceps tendon-femoral ligament (MQTFL) superiorly and the medial patellofemoral ligament (MPFL) inferiorly. The pediatric MPFL anatomy has been well described, but the precise anatomy of the MQTFL has only recently been described and studied in skeletally immature patients. PURPOSE: To describe the anatomic relationship between the MQTFL and its insertion on the quadriceps tendon and patella in pediatric specimens. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 22 pediatric cadaveric knee specimens were dissected to analyze attachment of the MQTFL to the quadriceps tendon and patella. Dissection was facilitated using lateral parapatellar arthrotomy followed by eversion of the extensor mechanism to evaluate MQTFL fibers from its undersurface. RESULTS: The mean specimen age was 7.4 years. Specimens were divided based on age into a younger cohort (1-2 years), middle cohort (4-8 years), and older cohort (9-12 years). The quadriceps tendon attachment (QTA) of the MQTFL proximal to the patella extended a median of 5.0 mm in the younger cohort, 11.4 mm in the middle cohort, and 12.0 mm in the older cohort, with significant differences found between the younger and middle cohorts (P < .047) and the younger and older cohorts (P < .001). The QTA as a percentage of patellar articular height averaged 44.4% across all specimens. The vertical height of the patella measured a median of 14.0 mm, 22.3 mm, and 27.3 mm in the younger, middle, and older cohorts, respectively. CONCLUSION: This study expands on the recently described anatomy of the pediatric MPFC to quantify the anatomic relationship between the MQTFL attachment to the quadriceps tendon and patella in a more clinically relevant cohort of donor specimens. CLINICAL RELEVANCE: As access to pediatric cadaveric tissue is extremely limited, a better understanding of MPFC and MQTFL anatomy will support surgeons in preoperative planning and intraoperative considerations for their approach to MQTFL and MPFL reconstruction. This may facilitate improved anatomic surgical stabilization of the patellofemoral joint in pediatric patients.

Paediatric reference anatomy for ACL reconstruction and secondary anterolateral ligament or lateral extra-articular tenodesis procedures.

OBJECTIVES: For iliotibial band (ITB) lateral extra-articular tenodesis or anterolateral ligamentous/capsular reconstruction with anterior cruciate ligament reconstruction, a clear understanding of the referenced anterolateral knee anatomy is critical-especially given the risk of injury to the physis or key anterolateral structures in the paediatric population, which is at high-risk for primary and secondary anterior cruciate ligament injury. The purpose of this study was to quantitatively assess the anatomy of the knee physes, paediatric lateral collateral ligament (LCL) origin, popliteus origin and ITB tibial insertion. METHODS: Nine paediatric cadaveric knee specimens with average age 4.2 years (range 2 months-10 years) underwent dissection to identify the LCL's and popliteus' femoral origins and the ITB's tibial insertion. Metallic marking pins demarcated precise anatomic attachment sites, and subsequent computerised tomography scans enabled quantified measurements among them. RESULTS: LCL & Popliteus: On the femur, the popliteus origin lay consistently deep to the LCL and inserted both distally and anteriorly to the LCL, a mean distance of 4.6 mm (range 1.9-7.6; standard deviation 2.0). From the joint line, the LCL lay a mean distance of 12.5 mm proximally while the popliteus measured a mean of 8.2 mm. Both were consistently distal to the physis. The LCL was a mean distance of 4.4 mm (range 1.0-9.5) and the popliteus was a mean distance of 8.2 (range 1.7-12.5) from the physis. ITB insertion: The ITB insertion at Gerdy's tubercle had an average footprint measuring 28.2 mm2 (range 10.3-58.4) and the ITB centre lay proximal to the physis in 6 specimens (mean age 4.2 years, median 2.5 years) and distal in 3 specimens (mean age 1.5 years, median 4 months). Mean distance from the footprint centre to the physis was 1.6 mm proximal (range 7.1 proximal - 2.2 distal). CONCLUSION: This study describes relative and quantitative positions of the femoral LCL and popliteus origins and tibial ITB attachment and their respective physeal relationships. Knowledge of paediatric anterolateral knee anatomy will help guide essential future research and procedures providing extra-articular anterolateral rotatory stabilisation and may help reduce iatrogenic physeal injury risk. LEVEL OF EVIDENCE: N/A (descriptive anatomic study).

The Axillary Nerve Danger Zone in Percutaneous Fixation in the Pediatric Shoulder: The "1-Mountain-3-Valleys" Principle.

BACKGROUND: Adult literature cites an axillary nerve danger zone of 5 to 7 cm distal to the acromion tip for open or percutaneous shoulder surgery, but that may not be valid for younger patients. This study sought to quantify the course of the axillary nerve in adolescent patients with reference to easily identifiable intraoperative anatomic and radiographic parameters. METHODS: A single-institution hospital database was reviewed for shoulder magnetic resonance images (MRIs) in patients 10 to 17 years old. One hundred and one MRIs from patients with a mean age of 15.6 ± 1.2 years (range, 10 to 17 years) were included. Axillary nerve branches were identified in the coronal plane as they passed lateral to the proximal humerus and were measured in relation to identifiable intraoperative surface and radiographic landmarks, including the acromion tip, apex of the humeral head, lateral physis, and central apex of the physis. The physeal apex height (i.e., 1 "mountain") was defined as the vertical distance between the most lateral point of the humeral physis (LPHP) and the central intraosseous apex of the physis. RESULTS: Axillary nerve branches were found in all specimens, adjacent to the lateral cortex of the proximal humerus. A mean of 3.7 branches (range, 2 to 6) were found. The mean distance from the most proximal branch (BR1) to the most distal branch (BR2) was 11.7 mm. The pediatric danger zone for the axillary nerve branches ranged from 6.6 mm proximal to 33.1 mm distal to the LPHP. The danger zone in relation to percent of physeal apex height included from 62% proximal to 242% distal to the LPHP. CONCLUSIONS: All branches were found distal to the apex of the physis (1 "mountain" height proximal to the LPHP). Distal to the LPHP, no branches were found beyond a distance of 3 times the physeal apex height (3 "valleys"). In children and adolescents, percutaneous fixation of the proximal humerus should be performed with cortical penetration outside of this range. These parameters serve as readily identifiable intraoperative radiographic landmarks to minimize iatrogenic nerve injury. CLINICAL RELEVANCE: This study provides valuable landmarks for percutaneous approaches to the proximal humerus. The surgical approach for the placement of percutaneous implants should be adjusted accordingly (i.e., performed at least 1 mountain proximal or 3 valleys distal to the LPHP) in order to prevent iatrogenic injury to the axillary nerve.

Epidemiological Study of the Discoid Meniscus: Investigating Demographic-Based Predictors in Large-Scale Claims Database.

Purpose To better define the epidemiology of discoid meniscus by analyzing a large, national database for incidence rates and associations with demographic variables. Methods From Optum's Clinformatics® Data Mart Database, incidence rates and proportions of reported racial categories - Asian, Black, Hispanic, and Caucasian - of diagnosed discoid meniscus cases (n = 198) in the study population of patients receiving arthroscopic meniscectomy or repair procedures (n = 60,042) were calculated and compared via chi-square tests to the total population. To control for age, sex, and socioeconomic factors such as income, multivariable logistic regression analysis was performed. Results Proportions of discoid meniscus patients who were Asian, Black, Hispanic, or Caucasian were <6%, <7%, 15.7%, and 73.7%, respectively; proportions of each racial category in the study population were 2.2%, 7.4%, 9.9%, and 80.5%, respectively. Incidence rates per 1000 for these were 5.95, 2.92, 5.19, and 3.01, respectively. After adjusting for age, sex, and income, race was not a statistically significant predictor. Odds of a discoid meniscus diagnosis decreased by 6% for each increment in age (p <0.001) and by 40% if male (p <0.001) in our total study population. In patients <=20 years old, sex was not a significant risk factor. Conclusions Younger age and female sex were identified as significant predictors for symptomatic discoid meniscus in the total study population. Unlike prior studies, this investigation did not show a significant association between this condition and race in the US, potentially increasing the diagnostic accuracy and estimated pretest probabilities for this condition based on patient demographics. What this study adds to existing knowledge This study provides new data on the role racial category plays in estimating the risk of having a symptomatic discoid meniscus requiring arthroscopic management, finding that it is unlikely to be a significant factor when controlling for other demographic variables. Furthermore, we report incidence statistics for this pathology in Black and Latinx populations, which so far have had little representation in peer-reviewed published literature on discoid meniscus epidemiology. In addition, this study suggests that age and sex possess statistically significant associations with a diagnosis of discoid meniscus requiring arthroscopic management, with the risk of diagnosis decreasing with age and increasing if female.