The purpose of this project is to evaluate the effect of the Compass™ Universal Hinge external fixator on the outcome of patients following acute dislocation of the knee

Prospective randomized outcome study. Patients will be randomized either into the control group (Group A) or the study group (Group B) based on a computer generated randomization table. Both groups will undergo an identical surgical protocol, as outlined below. The only difference is that patients in Group A will have a range of motion external brace placed following surgery, while patients in Group B will have a CKH placed. The rehabilitation protocol for the two groups will be identical, as outlined below. Both groups will undergo an Anterior Cruciate Ligament (ACL) reconstruction on a delayed basis two months following surgery, if the ACL was torn during the knee dislocation. The ACL reconstruction will be delayed in both groups if a minimum range of motion of 10-90 degrees has not been attained.

Surgical Protocol : Approximately 10 - 21 days following the injury, patients will undergo the first surgical procedure on their knee dislocation. During the first procedure, they will have a Posterior Cruciate Ligament (PCL) reconstruction using an achilles tendon allograft, with the direct onlay, two bundle technique. Additionally, any damage to either the posterior medial or posterior lateral corner will be repaired (not reconstructed), and any meniscus pathology will be addressed. The final step of this first procedure will be applying the CKH to patients randomized to the compass group (the alignment pins will be placed prior to repair of the corner). Patients will undergo an ACL reconstruction (if necessary) approximately 8 weeks following the initial surgery, when the CKH will be removed. Additional surgeries will be performed on patients to treat motion problems/arthrofibrosis as well as recurrent instability on an "as-needed basis."

Rehabilitation Protocol - aggressive rehabilitation will be started on the day following surgery. Patients will be placed in Continuous Passive Motion (CPM) machines with an initial range of motion of 0 - 30 degrees. The hinge will be locked into full extension for at least 4 hours per day. We will continue CPM for two weeks, with a goal of increasing by at least 10 degrees per day to 90 degrees of flexion. Weightbearing will be allowed as tolerated with the hinge locked in extension.

Inclusion Criteria:

• Trauma patient with a knee dislocation that requires surgical repair
• Adult patient (19 years and older)

Exclusion Criteria:

• Patients unable or unwilling to comply with follow-up gait, radiographic and clinical evaluations necessary to complete the study
• Patients unable or unwilling to give informed consent and/or who have no responsible family member willing to give consent
• Pregnant women
• Prisoners

Baseline to 12 months