COLLATERAL (LCL, MCL) & POSTERO LATERAL CORNER (PLC) LIGAMENT RECONSTRUCTION

The lateral and medial collateral ligaments are primary restraints to side to side or coronal plane instability and the posterolateral corner ligament is an important restraint to varus (bowing) or recurvatum (hyperextension) forces across the knee.  Rupture of one or several of these ligaments may require consideration of repair or reconstruction depending upon the alignment of the patient’s knee and the degree of laxity and instability.

The Lateral Collateral Ligament (LCL) is a cord like structure which runs on the outside or lateral aspect of the knee from the femur down to the fibula, not actually attaching to the tibia. It usually is 5 to 7cms in length and approximately 1cm in diameter and runs from the lateral femoral epicondyle on the femur onto the uppermost tip of the fibula (fibula head) in front of the lateral hamstring tendon (biceps femoris) insertion.

It can rupture in isolation or in conjunction with other ligament injuries including more commonly the ACL, PCL, Popliteus and Popliteofibular ligament (see Posterolateral Corner and Multiligament Reconstruction). It can heal with appropriate splinting, but if it fails to heal can lead to residual instability in the side to side plane when stepping towards the side of the injured knee. Once additional ligament injuries and instability have been assessed for (ACL, PCL, Posterolateral Corner), the LCL can be repaired by grasping the ends of the LCL with sutures or detaching it on a bone block and advancing it until it is appropriately tensioned and reattaching it to femur or fibula with a series of suture anchors or bone staples.

If the LCL was ruptured across the mid portion or if the quality and volume of tissue is poor, it can be reconstructed using autogenous hamstring graft using a combination of soft tissue and bony fixation techniques with a small drill hole through the fibula and through the femur at the level of the lateral femoral epicondyle. The incision used to repair or reconstruct the LCL is influenced by the site of detachment/rupture, the quality of the tissue, additional ligaments/structures involved, strength of patient’s bony integrity and their level of demand.

Usually it necessitates a 3 to 4 fingerbreadth length incision, and a period of splinting of 8 to 12 weeks. Unlike the MCL which requires an initial period of splinting in flexion, the LCL reconstruction requires splinting initially in extension. A hinged range of motion brace and graduated protective weight bearing with use of crutches is necessary and occasionally a medial unloader brace which distracts the inner or medial aspect and compresses the outer or lateral aspect of the knee, taking tension off the LCL repair/reconstruction.

The Medial Collateral Ligament (MCL) is a broad flat band that runs from the medial or inner aspect of the distal femur down onto the underlying tibia, with the femoral attachment starting on the medial femoral epicondyle, running for a length of 10 to 15cms down to the tibial attachment, four to five finger breadths below the joint line. The MCL has superficial and deep components and attaches to the knee joint capsule at its posterior extent, and is relatively free in its superficial and anterior most portions. It provides stability in a side to side direction in conjunction with the posterior capsule, and can be torn free from its attachment to the femur (most commonly) or tibial attachment and less commonly in the mid substance.

Usually the MCL will heal without need for surgery, and splinting early with the knee slightly bent (30 degrees of knee flexion) initially, with graduated range of motion and weight bearing is usually favourable to allow it to heal with minimum residual ligament elongation and laxity. In some cases of complete MCL rupture where the posterior capsule was also torn, the knee will remain unstable in the coronal (side to side) plane, and consideration of reconstruction becomes necessary. Once additional ligament injuries and instability have been assessed for (ACL, PCL, Posterolateral Corner, Posteromedial Corner), the MCL can be repaired with suturing, advancement and reattachment to the site it was detached from (femur or tibia) with a series of suture anchors or bone staples, or if it was across the mid portion or if the quality and volume of tissue is poor, it can be reconstructed using autogenous hamstring graft harvested in close proximity from their attachment at the anterior edge of the tibial MCL attachment site, using a combination of soft tissue and bony fixation techniques.

The incision used to repair or reconstruct the MCL is influenced by the site of detachment/rupture, the quality of the tissue, additional ligaments/structures involved, strength of patient’s bony integrity and their level of demand. Usually it necessitates a 3 to 4 fingerbreadth length incision, and a period of splinting of 8 to 12 weeks. Patients usually regain good stability in the side to side plane, with minor residual laxity and with appropriate physiotherapy should regain their range of motion, with particular attention needed to help get full extension after periods of splinting initially in flexion.

The Postero-Lateral Corner (PLC) is a complex of tissue including tendons and ligaments at the rear and lateral aspect of the knee and is usually injured as a result of high energy twisting or deceleration forces and or a blow from the front and inner aspect of the knee forcing it into hyperextension and outwards bowing (varus). Common injuries contributing towards this include skiing, motorbike accidents and football tackles. It usually includes some combination of injuries to the popliteus tendon, popliteofibular ligament and the arcuate ligament. It is quite often injured in conjunction with the posterior cruciate ligament and or the lateral collateral ligament, and with less frequency, the anterior cruciate ligament, lateral hamstring (biceps femoris) and iliotibial tendons. These structures are vital to the long term stability and function of the knee and if allowed to heal in an elongated manner can result in progressive dysfunction of the knee, ranging from a sensation of instability, lack of confidence, progressive bowing sideways (varus deformity) and / or front on (recurvatum deformity) and eventually arthritis with pain, swelling and stiffness.

Often PLC injuries are missed early as the focus of attention shifts towards a more obvious injury such as an ACL or PCL injury. If a patient undergoes an ACL or PCL reconstruction in the setting of an untreated posterolateral corner (PLC) injury, the ACL / PCL are at greater risk for failure. PLC deficiency is best diagnosed both clinically and with advanced imaging (MRI).

Treatment is influenced by the timing of the diagnosis relative to the injury, with the ideal scenario being to undergo surgical repair where possible, by reattaching the avulsed ligaments/tendons to their parent bony beds using small drill holes in the bone and suture anchors or end to end tendon and ligament repairs with strong sutures and augmentation where necessary with tendon grafts and reconstruction. Graft choices are influenced by which other structures have been injured, and how many ligaments need reconstruction and may require consideration of harvesting tissue from both the injured and the opposite uninjured leg.

It usually involves a straight incision at the rear and outside of the knee measuring 8 to 10 cm’s in order to gain access to the posterior capsule, lateral hamstrings (biceps femoris), fibula head, and identify an important nerve (common peroneal nerve) that is vital for the normal power and sensation of the calf and foot, before identifying and repairing or reconstructing where necessary, the popliteus tendon, popliteofibular ligament and arcuate ligament. These structures are easy to stretch or tear in the early stages following surgery and use of a hinged brace to help splint and protect the repairs is important and will usually be worn for at least 2 – 3 months.