Lateral Collateral Ligament (LCL) Repair and Posterolateral Corner Reconstruction
What Are the LCL and the Posterolateral Corner (PLC)?
The lateral collateral ligament (LCL), also called the fibular collateral ligament, sits on the outer side of the knee and limits the joint from opening to the side (in a varus direction). This ligament does not act alone; together with the posterolateral capsule, the popliteofibular ligament and the popliteus tendon, it forms a functional unit called the posterolateral corner (PLC). The PLC is an important stabiliser that controls both sideways opening and external rotation of the knee, and because injuries here may not be limited to one structure, accurate diagnosis and treatment require expertise.
How Does the Injury Happen and Why Does It Matter?
PLC injuries occur through a direct blow to the inner side of the knee, excessive external rotation or hyperextension, and are often seen in high-energy injuries. An isolated PLC injury is relatively rare; in most cases it occurs together with an anterior or posterior cruciate ligament injury, and this combination may be part of a multiple ligament knee injury. Missing a PLC injury matters: an unrecognised PLC injury can cause a cruciate ligament graft that is repaired at the same time to stretch out over time and lead to treatment failure.
How Do the Symptoms Appear?
The most common complaints are pain and swelling on the outer side of the knee and instability felt especially when bearing weight. Patients may describe a sense of the knee “opening out” or giving way; going down stairs, turning and uneven ground can increase this feeling. A PLC injury is sometimes accompanied by involvement of the nerve that passes on the outer side of the knee; in that case there may be weakness in lifting the foot or numbness on the top of the foot, and these findings should be assessed carefully.
Diagnosis: Examination and Imaging
Diagnosis begins with a detailed history and specific examination tests directed at the outer side of the knee; sideways opening at different angles and external rotation are assessed and the two sides are compared. X-rays show the bony anatomy, any avulsion fractures and the alignment; MRI reveals the state of the LCL, popliteus and popliteofibular ligament and any associated cruciate, meniscus or cartilage injuries. In chronic cases, weight-bearing films that assess leg alignment also contribute to the plan, because varus alignment can increase the load placed on the repair.
Who Is a Candidate: Non-Surgical or Surgical?
Non-surgical treatment may be tried for mild, isolated injuries that keep the knee relatively stable; this approach uses a brace, protected weight-bearing and progressive physiotherapy. By contrast, complete injuries that cause marked instability and cases that occur together with a cruciate ligament injury usually require surgery. Timing matters: selected acute injuries may benefit from direct repair early on, while in delayed cases or where tissue quality is poor, graft reconstruction gives more reliable results.
Repair or Reconstruction?
At the centre of the surgical decision is whether the structure can be repaired with direct suture or needs to be rebuilt with a graft. In acute injuries where the ligament has avulsed from bone and the tissue quality is good, direct repair may be possible. However, if the ligament is torn in its mid-substance, if more than one structure is involved or if the injury has become chronic, an anatomic reconstruction that rebuilds the LCL, popliteofibular ligament and popliteus tendon with a graft is preferred. When many structures on the outer side of the knee are damaged, they are usually addressed together in the same session.
How the Operation Is Done
Arthroscopy may be used to assess the structures inside the joint and to address any associated cruciate, meniscus or cartilage problems. However, because the LCL and PLC lie on the outer side of the knee, outside the joint, their repair or reconstruction is usually carried out through open surgery. In reconstruction, an autograft or allograft is used to fix the structures at their anatomical points, and the nerve that passes on the outer side of the knee is protected during the procedure. The general principles of knee ligament surgery are summarised on the knee ligament surgery page.
Anaesthesia and Duration
The procedure is carried out under general or regional anaesthesia, often with a nerve block added for pain control. The duration depends on whether a repair or a reconstruction is done, how many structures are addressed and any accompanying cruciate or meniscus work. In cases that include multiple ligament repair, the operation takes longer and usually requires a short hospital stay.
The First Period After Surgery
Protecting the repaired knee and the graft is the priority in this period. The knee is usually supported in a brace, and protected weight-bearing is applied for about the first six weeks; crutches may be used during this time. Pain and swelling are managed with ice, appropriate medication and elevation. Range of motion exercises may begin gradually, with a programme that respects the security of the graft, about two weeks after surgery.
Rehabilitation, Recovery and Return to Sport
Rehabilitation progresses in stages and is guided by goals reached rather than a fixed calendar: protected movement and control of swelling first, then gradual strengthening of the thigh and hip muscles, and balance and functional work in later phases. Working with an experienced physiotherapist supports the process. Full function of the repaired knee and return to sport is usually a process spread over months; for these complex reconstructions, return to normal activities is most often planned in the range of six to nine months. The timescale varies with the patient, the extent of the injury and adherence to rehabilitation, and no fixed date is promised.
Risks and When to See a Doctor
The risks of this surgery include joint stiffness, loosening or failure of the graft, persistent instability, infection, blood clots and involvement of the nerve that passes on the outer side of the knee. After surgery, increasing redness, drainage, fever, steadily worsening pain, weakness in lifting the foot or numbness and colour change in the foot should be assessed without delay. Before surgery, persistent instability and a sense of giving way on the outer side of the knee warrant a proper assessment. To have a knee problem evaluated, you can contact Assoc. Prof. Serkan Sürücü.