Knee Ligament Injuries

Ligaments are dense strands to tissue that link two bones together across a joint. There are 4 main ligaments that span the knee joint: Lateral Collateral Ligament (LCL), Medial Collateral Ligament (MCL), Posterior Cruciate Ligament (PCL) and Anterior Cruciate Ligament (ACL). Ligament tears rarely occur in isolation and many patients will have a concomitant bone bruise or cartilage tear. LCL and PCL tears are unusual injuries and commonly occur as a result of high energy injuries like car accidents causing a knee dislocation. Medial Collateral and Anterior Cruciate ligament injuries are very common and discussed individually below:

                                       Diagram of an MCL tear                  Brace commonly used for an ACL tear

MCL Tears
Medial Collateral ligament (MCL) tears are common and patients complain of sharp pain on the inside (medial) aspect of the knee after a hit from the lateral (outside) aspect of the knee. Some patients complain of a feeling of instability when putting weight on the leg.   Ligament tears are graded on the severity of the ligament damage from 1-3, with a grade 3 sprain regarded as a complete rupture of the ligament.  I will generally obtain an MRI of the knee to make sure there are no other injuries such as a meniscus tear which commonly occur in conjunction with an MCL tear. For isolated MCL tears, surgery is not needed and most patients are treated with a hinged knee brace and gradual rehabilitation with physical therapy.  The irritation over the tear is stubborn and persists for several months after the injury.

Pivot Shift with ACL tear

ACL Tear
Anterior Cruciate ligament (ACL) tears commonly occur in conjunction with pivoting sports (basketball, football, skiing) and are much more common in female athletes.  Most patients will describe a history of a pop in the knee and most have a large effusion (accumulation of fluid inside the joint).  Most are able to stand and walk within a few days but many describe feeling a shifting or loosening of the knee joint especially when changing direction.  The diagnosis is confirmed by MRI scan which will show the ligament tear clearly. Initial management will consist of physical therapy to help regain motion in the knee with special focus on regain quadriceps strength which diminishes rapidly after the injury.  Surgery to reconstruct the ligament is often needed to restore stability to the knee but many patients choose not to undergo surgical reconstruction and can be effectively managed with brace wear.  I usually recommend reconstruction with an allograft (cadaveric) tendon to avoid having to remove one of the patient’s tendons to recreate the ligament.  Recovery is fairly quick and most patients are able to stand and walk comfortably within 4 weeks of surgery.

                               Types of ACL tears                                  ACL Reconstruction using a Transfix system