Vascular Safe Zone During Percutaneous Pinning of the Distal Femur.

PURPOSE: During percutaneous pinning of the pediatric distal femur, iatrogenic vascular damage in the medial thigh is a frequent concern. The proximity of a proximal-medial pin to these vessels has never been studied in children. This study describes a radiologic vascular safe zone that is easily visualized during surgery (wherein the superficial femoral vessels are safely posterior). METHODS: Patients ≤16 years old with magnetic resonance imaging of one or both femora between 2005 and 2020 were retrospectively reviewed. The "at-risk level" (ARL) was defined as the distal-most axial image with a femoral vessel anterior to the posterior condylar axis. A standardized retrograde lateral-to-medial pin was templated. A correlation matrix and least squares regression identified age and physeal width (PW) as ideal independent variables. A vascular safe zone above the medial femoral condyle (MFC) was modeled as a multiple of PW (i.e. x*PW) and needed to satisfy 3 age-dependent criteria: (1) at the ARL, the pin is medial to the vessels, (2) the pin exits the medial thigh before the ARL, and (3) the chosen "vascular safe zone" (x*PW) is always distal to the ARL. RESULTS: Forty-three patients averaging 7.1±3.9 (0.3-16) years old were included. Intra-Class correlation coefficients were excellent (0.92-0.98). All measurements strongly correlated with age ( r =0.76-0.92, P <0.001) and PW ( r =0.82-0.93, P <0.001). All patients satisfied criteria 1. Criteria 2 was satisfied in all patients ≥6 years old, 86% of children 4-5, and only 18% of children ≤3. In children >3 years old, the largest safe zone that satisfied criteria 3 was 2×PW. On average, the ARL was 2.5×PW (99% CI 2.3-2.7) above the MFC. The average ARL in children ≥6 years old was significantly higher than 2×PW (162 mm vs. 120 mm, P <0.001). CONCLUSION: During passage of a distal femur pin into the medial thigh, children ≥6 years old have a vascular safe zone that extends 2×PW proximal to the MFC. Surgeons should be cautious with medial pin placement in children 4-5 years old and, if possible, avoid this technique in children ≤3. LEVEL OF EVIDENCE: IV.

Delayed diagnosis and treatment of a distal patellar tendon avulsion in an adolescent.

Distal patellar tendon avulsions are uncommon. While much is known about proximal patella tendon ruptures, there are very few reports to guide treatment of a patellar tendon disruption near the tibial tuberosity. Moreover, delayed diagnosis and treatment presents additional challenges. We present a distal patellar tendon avulsion in an adolescent whereby diagnosis and treatment were delayed due to a distracting nearby contaminated wound. The tendon was separated from post-traumatic scar then repaired back to its native footprint using suture anchors. This report aims to increase awareness of this rare diagnosis as well as provide details about our chosen treatment and rehabilitation protocol.