Knee Ligament Surgery
What Is Knee Ligament Surgery?
Knee ligament surgery is the collective name for the operations that correct the instability following a tear of one or more of the ligaments stabilising the knee. Four main ligaments support the joint: the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament together with the posterolateral corner (LCL and PLC). They connect the thigh bone to the shin bone and limit how far the knee slides forwards and backwards, opens sideways and rotates.
Surgery aims to restore the job the ligament used to do, so the knee stays controlled in daily life and sport. In an unstable knee, repeated episodes of giving way put the meniscus and the joint cartilage at additional risk. The decision is never taken from an MRI image alone: symptoms, the laxity found on examination, age, occupational demands and sporting goals all shape the plan.
Which Ligaments Are Injured and When Does Surgery Come Up?
The decision depends on which ligament is torn, how severe the tear is and what else was injured at the same time. Each ligament is covered in more detail on its own page:
- Anterior cruciate ligament: a complete tear rarely heals on its own, and reconstruction is considered for patients whose knee gives way during pivoting and change of direction. The technique is described under anterior cruciate ligament (ACL) reconstruction.
- Posterior cruciate ligament: most isolated, low-grade injuries can be managed with a strengthening-led programme, while high-grade tears and those forming part of a multiligament pattern are assessed for posterior cruciate ligament repair or reconstruction.
- Medial collateral ligament: because its blood supply is good, the majority of isolated injuries heal with protected motion and bracing; persistent valgus instability is what brings medial collateral ligament (MCL) reconstruction into the discussion.
- Lateral collateral ligament and posterolateral corner: these injuries often accompany a cruciate ligament tear, and missing them is a recognised cause of graft failure, so lateral collateral ligament repair and posterolateral corner reconstruction needs separate planning.
Who Is a Candidate for Surgery?
Surgery is not the first option for everyone. In isolated, low-grade collateral ligament injuries, and in people who do not need pivoting activity and whose knee stays controlled on examination, non-operative treatment is reasonable. Repeated giving way, high-grade laxity, a repairable meniscus tear alongside the injury and the wish to return to contact or pivoting sport move the discussion towards surgery. Age alone is not decisive; activity level matters more.
A multiple ligament knee injury, in which more than one major ligament tears at the same time, is a separate category and requires surgery in the large majority of cases. Active infection, poorly controlled systemic illness, advanced joint arthritis and an inability to follow the rehabilitation programme can change the plan or delay the operation.
Preparing for Surgery: Motion, Swelling and Muscle Control
Timing matters, but so does whether the knee is ready. Operating on a swollen, stiff knee surrounded by weakened muscle increases the risk of stiffness afterwards, so many patients first settle the swelling, regain full extension and enough flexion and switch the quadriceps back on before a date is set.
Preparation also reviews the history, the examination, X-rays and MRI together with current medication, blood thinners and coexisting conditions. Collateral ligament and posterolateral corner injuries are an exception, because direct repair may only be feasible in the early weeks after the injury.
Repair or Reconstruction: What Is the Difference?
Knee ligament surgery rests on two basic approaches. In a repair, the torn ligament is stitched back to itself or fixed to the point of bone it pulled away from; this is possible when the tissue quality is good and the injury is addressed early. In a reconstruction the ligament cannot be salvaged, so a graft is used to recreate its path across the joint.
Because the environment inside the joint is unfavourable for healing, reconstruction is far more common for the cruciate ligaments. For the collateral ligaments and the posterolateral corner, repair can be preferred when the timing and the tissue quality allow it. The final choice can change in theatre, once the tissue can be seen directly.
Graft Choices, Tunnel Placement and Fixation
A graft may be taken from the patient's own tissue (autograft) or from a tissue bank (allograft). Common autograft sources are the hamstring tendons, part of the patellar tendon and the quadriceps tendon; temporary pain or weakness can occur where the graft was harvested. An allograft avoids an extra harvest site and can be useful when several ligaments must be reconstructed in one operation. The choice takes account of age, activity level, how many ligaments are involved and any previous knee surgery.
The graft is passed through tunnels drilled in the thigh bone and the shin bone and positioned as close as possible to the natural footprint of the ligament; accurate tunnel placement is one of the technical details that most strongly influences the result. Fixation may use an interference screw, a cortical button, a staple or a suture anchor. The intra-articular part is usually performed arthroscopically, while collateral ligament and posterolateral corner work is done through open incisions.
Multiligament Injuries: Single-Stage or Staged Surgery
When several ligaments are torn, whether they are all addressed in one sitting or in stages depends on the severity of the injury, the condition of the soft tissues and skin, any associated fractures and the patient's general health. Single-stage surgery means one rehabilitation process, while a staged approach may be safer in knees with damaged soft tissue or a high risk of stiffness. The detailed surgical plan is set out under multiple ligament knee reconstruction.
Because these injuries can occur with a knee dislocation, they require urgent assessment of the blood vessels and nerves. Injury to the popliteal artery behind the knee can threaten the circulation of the leg, while a peroneal nerve injury may show as an inability to lift the ankle and numbness over the top of the foot. Pulses and neurological findings are checked repeatedly and vascular imaging is arranged when needed; if these findings are present, the vascular or nerve problem takes priority over ligament surgery.
Anaesthesia, Operating Time and the First Weeks After Surgery
Knee ligament operations are generally performed under general or regional anaesthesia, with nerve blocks sometimes added for pain control. Reconstruction of a single ligament is usually shorter and can often be completed as a day case or with one overnight stay, whereas operations that address several ligaments take considerably longer.
The early aims are to control pain and swelling, protect the repair and prevent stiffness. The knee is usually supported in a brace, with the brace setting and the amount of weight allowed decided according to which ligament was treated. Protection rules after posterior cruciate ligament and posterolateral corner surgery differ from those after ACL surgery, so instructions are individual. Cold application and elevating the leg reduce swelling, while early ankle and foot movements and the measures your surgeon recommends lower the risk of clots.
Rehabilitation After Knee Ligament Surgery
Rehabilitation progresses by goals reached rather than by the calendar. The first phase focuses on keeping full extension, increasing flexion gradually, reactivating the quadriceps and normalising the walking pattern. The second phase brings in strengthening of the hip, thigh and calf muscles along with balance and proprioception work. The final phase adds running, jumping, controlled landing and change of direction step by step.
Both extremes cause problems: pushing too hard early can stretch the graft, while too much immobility leads to stiffness. The programme is therefore reviewed at each stage.
Returning to Work and Sport
Many patients with desk-based jobs can return within a few weeks, while work that involves prolonged standing, stairs, heavy lifting or kneeling takes longer. Return to sport is governed by criteria rather than by a date: a knee that is free of pain and swelling, full range of motion, strength that compares well with the uninjured leg, controlled jumping and landing quality, and confidence when changing direction. Reaching these criteria takes longer after multiligament surgery, and returning too early increases the risk of re-injury.
Risks, Complications and Factors That Affect the Outcome
As with any operation, knee ligament surgery carries risks: infection, bleeding into the joint, deep vein thrombosis and rarely pulmonary embolism, loss of movement and joint stiffness (arthrofibrosis), stretching or re-tearing of the graft, problems with the fixation devices, pain at the graft harvest site, numbness over the front of the knee and, rarely, injury to blood vessels or nerves. The injury itself and any accompanying meniscus and cartilage damage can also increase the long-term risk of joint arthritis.
The most important factor in the result is recognising every associated injury: a missed posterolateral corner or posterior cruciate ligament problem can undermine even a technically sound cruciate reconstruction. Malalignment of the leg increases the load carried by the reconstructed ligament. Pre-operative range of motion and muscle strength, smoking, body weight and adherence to rehabilitation also influence the outcome.
When Should You See a Doctor?
After surgery, increasing redness, discharge from the wound, fever, pain that keeps getting worse, one-sided calf swelling and tenderness, shortness of breath, numbness or weakness in the foot, or a change in its colour and temperature should be assessed without delay. Before surgery, a knee that gives way or locks, swells rapidly or cannot take weight needs medical review, and a suspected knee dislocation is an emergency. For a detailed assessment of your knee you can contact Assoc. Prof. Serkan Sürücü, and you may also want to review the other conditions covered under knee surgery.