summary Proximal Tibia Metaphyseal Fractures are fractures of the proximal tibia usually seen in children from 3 to 6 years of age. This fracture is significant for its tendency to develop a late valgus deformity, known as a Cozen's phenomenon, that must be monitored closely. Diagnosis can be confirmed with plain radiographs. Treatment is usually closed reduction and casting in extension with a varus mold. Late valgus deformity generally resolves with observation alone. Epidemiology Demographics most common in children 3-6 years of age Etiology Pathophysiology mechanism typically low-energy with valgus force across the knee creating incomplete fracture of proximal tibia can also result from torsional injury classic mechanism is a child going down a slide in the lap of an adult with leg extended Associated conditions Cozen's phenomenon a late valgus deformity etiology is unknown can occur regardless of treatment Anatomy Osteology tibia triangular shaped bone with apex anteriorly that broadens distally anteromedial border is subcutaneous blood supply posterior tibial a. provides nutrient and periosteal vessels nutrient vessels supply inner 2/3 of the tibial diaphysis Classification Descriptive Classification important radiographic parameters include complete vs incomplete majority are incomplete (greenstick, torus) displaced vs. nondisplaced associated fibula fracture presence of fibula fracture suggests higher energy Presentation Symptoms pain refusal to bear weight Physical exam usually minimal soft tissue swelling or deformity evaluate carefully for compartment syndrome Imaging Radiographs recommended views AP lateral findings incomplete vs. complete fracture presence of any angulation, usually valgus presence of proximal fibula fracture, which may indicate a more unstable fracture pattern Treatment Nonoperative long leg cast in extension with varus mold indications nondisplaced fractures technique place cast with varus mold (aim for slight overcorrection) casts are maintained for 4-6 weeks with serial radiographs weight bearing may be allowed after 2-3 weeks. reduction, long leg cast in extension with varus mold indications displaced fractures technique reduction usually done under conscious sedation casting is same as above Operative open reduction indications (rare) inability to adequately reduce a displaced fracture secondary to soft tissue interposition modalities limited open dissection to remove interposed soft tissue casting in near full extension, with or without supplemental k-wire fixation Techniques Closed reduction sedation usually performed under conscious sedation an angulated greenstick fracture is completed cast placed in near full extension with three-point varus mold Open reduction approach small medial incision over fracture site reduction removal of interposed soft tissue (periosteum, pes tendons, MCL) obtain an anatomic reduction under direct visualization may supplement with crossed k-wires postoperative place into well-molded cast Complications Valgus deformity (Cozen phenomenon) incidence as high as 50%-90% develops 5-15 months after injury maximum deformity observed at 12-18 months risk factors incomplete reduction concomitant injury to proximal tibia physis infolded periosteum injury to pes anserinus insertion, with loss of proximal tibia physeal tether, leading to asymmetric physeal growth treatment nonoperative observation may be observed for 12-24 months with expectation of spontaneous correction in most cases although some patients may have a persistant valgus deformity parents should be counseled in advance worst deformity at 18 months with an average valgus deformity of 18 degrees gradually resolves by 3 years, with an average, clinically irrelevant, of 6 degrees can result in S shaped tibia and persistent mechanical axis line that passed lateral to the center of the knee operative guided growth vs. osteotomy reserved for valgus deformities >15-20 degrees near skeletal maturity varus producing proximal tibia and fibula osteotomy medial proximal tibia epiphysiodesis Limb length discrepancy affected tibia is often longer (average 9mm) typically does not require intervention however parents should be counseled that this does not resolve Prognosis Valgus deformity usually resolves spontaneously