Lateral Collateral Ligament (LCL) Injury
What is an LCL injury?
The lateral collateral ligament (LCL) — also called the fibular collateral ligament — runs along the outer side of the knee, connecting the femur (thigh bone) to the fibula (the smaller bone of the lower leg). Its primary role is to resist varus forces — forces that push the knee outward — providing lateral stability to the joint. It works in conjunction with several other structures on the outer and back of the knee — the popliteus tendon, popliteofibular ligament, biceps femoris tendon, and posterolateral capsule — which collectively form what is known as the posterolateral corner (PLC) of the knee.
This anatomical context is important because isolated LCL injuries are actually relatively uncommon. When the lateral side of the knee is injured, the LCL is frequently damaged alongside one or more of these other posterolateral structures — and a posterolateral corner injury has significantly different management implications, including a higher rate of surgical intervention, than an isolated LCL sprain. Accurate diagnosis of what has been injured on the lateral side of the knee is therefore essential before a management plan is formed.
What causes an LCL injury?
LCL injuries typically occur from a varus force applied to the knee — a blow to the inner side of the knee that drives the knee outward — or from a hyperextension mechanism. Common situations include direct contact in football or rugby, landing awkwardly from a jump, or a fall that forces the knee outward. Because significant force is required to injure the lateral structures, many LCL injuries are high-energy and occur alongside other knee injuries — ACL ruptures, PCL tears and meniscal tears all co-occur with LCL injuries at higher rates than with isolated MCL injuries.
Peroneal nerve injury — the nerve that wraps around the fibular head just below the LCL attachment — is also a recognised complication of lateral knee trauma, producing foot drop, weakness in ankle eversion, and altered sensation on the outer lower leg and foot. Any lateral knee injury should be assessed for peroneal nerve involvement.
What are the symptoms?
Pain and tenderness along the outer side of the knee, localised to the fibular head and the course of the LCL. Swelling may be present but is often less pronounced than with medial or intra-articular injuries. A sense of instability — particularly with weight-bearing on the leg or with pivoting movements — is common in higher-grade injuries. In combined ligament injuries, the instability may be more pronounced and multidirectional.
How is it diagnosed?
Clinical assessment includes varus stress testing at both 0 and 30 degrees of knee flexion to assess LCL integrity, and posterolateral drawer and dial tests to assess the posterolateral corner structures. Peroneal nerve function is assessed as a routine part of any lateral knee examination. MRI is essential for confirming the grade of LCL injury and identifying associated posterolateral corner, cruciate ligament and meniscal pathology that will influence management.
A common clinical error is to diagnose an isolated LCL sprain without adequate imaging or assessment of the posterolateral corner — missing a PLC injury leads to persistent instability and poor outcomes even when physiotherapy is otherwise appropriate.
How can physiotherapy help?
The management approach depends critically on the injury grade and whether there is associated posterolateral corner or cruciate ligament involvement.
Grade 1 and 2 isolated LCL sprains — where the ligament is stretched or partially torn without significant instability — respond well to conservative physiotherapy management following a similar progression to MCL injuries. Protected weight-bearing in the acute phase, bracing to limit varus stress, progressive strengthening of the biceps femoris, lateral hip stabilisers and quadriceps, and proprioceptive rehabilitation form the core of the program. Return to sport timelines are similar to MCL injuries — four to eight weeks for lower-grade injuries, eight to twelve weeks for higher-grade isolated tears.
Grade 3 complete LCL tears with significant instability, and any injury involving the posterolateral corner, typically require orthopaedic specialist assessment to determine whether surgical reconstruction is indicated before physiotherapy rehabilitation is appropriate. Attempting aggressive rehabilitation of a reconstructed posterolateral corner without understanding the surgical repair is one of the most common causes of poor outcomes after these injuries. When surgery has been performed, physiotherapy follows the surgeon's protocol carefully — posterolateral corner reconstructions have specific precautions around varus stress and weight-bearing that must be respected during healing.
In the rehabilitation phase, clinical Pilates provides a controlled environment for lower limb strengthening without the varus stresses of some conventional exercises. Real time ultrasound assists with VMO and deep hip stabiliser retraining where inhibition from pain and swelling is affecting rehabilitation progress. For patients whose LCL injury occurred in a workplace or motor vehicle accident, WorkCover and CTP funded rehabilitation is available.
Our physiotherapists Eliane Machado, Bethany Kippen and Emma Cameron all have experience in knee ligament injury management and are members of the Australian Physiotherapy Association.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
The lateral collateral ligament (LCL) — also called the fibular collateral ligament — runs along the outer side of the knee, connecting the femur (thigh bone) to the fibula (the smaller bone of the lower leg). Its primary role is to resist varus forces — forces that push the knee outward — providing lateral stability to the joint. It works in conjunction with several other structures on the outer and back of the knee — the popliteus tendon, popliteofibular ligament, biceps femoris tendon, and posterolateral capsule — which collectively form what is known as the posterolateral corner (PLC) of the knee.
This anatomical context is important because isolated LCL injuries are actually relatively uncommon. When the lateral side of the knee is injured, the LCL is frequently damaged alongside one or more of these other posterolateral structures — and a posterolateral corner injury has significantly different management implications, including a higher rate of surgical intervention, than an isolated LCL sprain. Accurate diagnosis of what has been injured on the lateral side of the knee is therefore essential before a management plan is formed.
What causes an LCL injury?
LCL injuries typically occur from a varus force applied to the knee — a blow to the inner side of the knee that drives the knee outward — or from a hyperextension mechanism. Common situations include direct contact in football or rugby, landing awkwardly from a jump, or a fall that forces the knee outward. Because significant force is required to injure the lateral structures, many LCL injuries are high-energy and occur alongside other knee injuries — ACL ruptures, PCL tears and meniscal tears all co-occur with LCL injuries at higher rates than with isolated MCL injuries.
Peroneal nerve injury — the nerve that wraps around the fibular head just below the LCL attachment — is also a recognised complication of lateral knee trauma, producing foot drop, weakness in ankle eversion, and altered sensation on the outer lower leg and foot. Any lateral knee injury should be assessed for peroneal nerve involvement.
What are the symptoms?
Pain and tenderness along the outer side of the knee, localised to the fibular head and the course of the LCL. Swelling may be present but is often less pronounced than with medial or intra-articular injuries. A sense of instability — particularly with weight-bearing on the leg or with pivoting movements — is common in higher-grade injuries. In combined ligament injuries, the instability may be more pronounced and multidirectional.
How is it diagnosed?
Clinical assessment includes varus stress testing at both 0 and 30 degrees of knee flexion to assess LCL integrity, and posterolateral drawer and dial tests to assess the posterolateral corner structures. Peroneal nerve function is assessed as a routine part of any lateral knee examination. MRI is essential for confirming the grade of LCL injury and identifying associated posterolateral corner, cruciate ligament and meniscal pathology that will influence management.
A common clinical error is to diagnose an isolated LCL sprain without adequate imaging or assessment of the posterolateral corner — missing a PLC injury leads to persistent instability and poor outcomes even when physiotherapy is otherwise appropriate.
How can physiotherapy help?
The management approach depends critically on the injury grade and whether there is associated posterolateral corner or cruciate ligament involvement.
Grade 1 and 2 isolated LCL sprains — where the ligament is stretched or partially torn without significant instability — respond well to conservative physiotherapy management following a similar progression to MCL injuries. Protected weight-bearing in the acute phase, bracing to limit varus stress, progressive strengthening of the biceps femoris, lateral hip stabilisers and quadriceps, and proprioceptive rehabilitation form the core of the program. Return to sport timelines are similar to MCL injuries — four to eight weeks for lower-grade injuries, eight to twelve weeks for higher-grade isolated tears.
Grade 3 complete LCL tears with significant instability, and any injury involving the posterolateral corner, typically require orthopaedic specialist assessment to determine whether surgical reconstruction is indicated before physiotherapy rehabilitation is appropriate. Attempting aggressive rehabilitation of a reconstructed posterolateral corner without understanding the surgical repair is one of the most common causes of poor outcomes after these injuries. When surgery has been performed, physiotherapy follows the surgeon's protocol carefully — posterolateral corner reconstructions have specific precautions around varus stress and weight-bearing that must be respected during healing.
In the rehabilitation phase, clinical Pilates provides a controlled environment for lower limb strengthening without the varus stresses of some conventional exercises. Real time ultrasound assists with VMO and deep hip stabiliser retraining where inhibition from pain and swelling is affecting rehabilitation progress. For patients whose LCL injury occurred in a workplace or motor vehicle accident, WorkCover and CTP funded rehabilitation is available.
Our physiotherapists Eliane Machado, Bethany Kippen and Emma Cameron all have experience in knee ligament injury management and are members of the Australian Physiotherapy Association.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
