You are presented with an 8-year-old male with a progressive limp, a 3.5 cm leg length discrepancy (LLD), and genu valgum. Below is the standing teleoroentgenogram. Based on the imaging and clinical history of a minor trauma 3 years ago, what is your primary diagnosis, and what investigation is required to plan your intervention?
Candidate: The patient has a post-traumatic distal femoral physeal bar, likely a Salter-Harris V injury. This has caused a tethering of the physis, leading to the valgus deformity and LLD. I would order an MRI with physeal mapping sequences to quantify the size, location, and percentage of the physeal bar.
Candidates often jump immediately to "I will perform a Langenskiold procedure." Failing to first perform precise 3D physeal mapping or failing to mention skeletal age assessment (e.g., Sanders classification) to predict remaining growth is a significant weakness. Examiners want to see you quantify the bar percentage—if it's >50%, simple resection is rarely successful.
The patient has a post-traumatic distal femoral physeal arrest. My management would include: 1. Quantification: MRI with 3D fat-saturated sequences to create a topographic map of the bar. 2. Growth Prediction: Use of a hand/wrist radiograph for skeletal age (Sanders Stage 1) to determine remaining growth potential. 3. Classification: Identify if the bar is central (LLD), peripheral (angular deformity), or combined. 4. Surgical Planning: If <50% of the physis, I would offer Langenskiold resection with fat interposition, coupled with guided growth (medial hemiepiphysiodesis) to address the mechanical axis.
During the Langenskiold procedure, you have resected the osseous bridge. You are now considering the interposition material. What are your options, and what specific steps must you take to prevent the recurrence of the bony bridge?
Candidate: I would use autologous fat harvested from the gluteal region. I need to ensure the defect is packed tightly to prevent hematoma formation, as blood creates a scaffold for bone regeneration. Finally, I would secure the cortical window with a small plate to prevent the graft from extruding.
Candidates often forget the critical step of arthroscopic inspection. Even with fluoroscopy, ensuring you have reached "pearly white" healthy physeal cartilage is essential. Relying solely on fluoroscopy is considered outdated; direct visualization or endoscopic confirmation is the current standard of care.
Autologous fat is the gold standard for its biological inertness. To ensure success: 1. Verification: Utilize 2.7mm arthroscopic visualization to confirm a continuous rim of healthy physeal cartilage. 2. Packing: The graft must be packed under pressure to exclude air and fluid. 3. Containment: Replace the cortical window and secure it with a low-profile plate. 4. Rehabilitation: Strict non-weight-bearing is mandatory for 4 weeks post-op to prevent a metaphyseal stress fracture through the cortical window.
Detailed Chapters & Topics
Dive deeper into specialized chapters regarding pediatric-orthopedic-cases-25