Study of New Catheter & Pressure Monitor System to Help Prevent Compartment Syndrome From Developing in the Injured Leg

Inclusion Criteria: * Subject with a tibial shaft fracture requiring intramedullary nailing or bicondylar tibial plateau fracture requiring application of a knee-spanning external fixator. * Operative procedure (nailing or external fixation) performed within 72 hours of injury. * The Subject is between 18 and 60 years of age. * Able to understand what he/she is being asked to do, willing/able to understand and sign the Informed Consent to return for follow-up visits at 2 weeks and 3 months post surgery. Exclusion Criteria: * Current evidence of CS prior to Study. * Surgical stabilization will result in the presence of a bead pouch or wound vac or other dressing that would interfere with placement of any of the three Catheters in the anterior compartment. * The Subject has a medical condition(s) that precludes use of Catheters, such as dermatologic conditions, immunological deficits or traumatic skin lesions that interfere with Catheter placement. * The Subject has co-morbidities that may place the Subject at risk of hypotension (e.g., significant blood loss, heart failure, significant chest or abdominal trauma, septicemia, pelvic fractures, femur fractures or massive soft tissue trauma.) * Likely problems, in the investigator's judgment, with maintaining follow-up (including developmental delay, address greater than 2 hours drive from the treating institution, substance abuse problems, intoxication, current or pending incarceration, etc.).