The Knee Joint

The knee is a “hinge joint” made up of four bones. The femur (thighbone) is the bone connecting the hip to the knee. The tibia (shinbone) connects the knee to the ankle. The patella (kneecap) is the small bone in front of the knee that slides over the knee joint as the knee bends. And, the fibula is a shorter and thinner bone running parallel to the tibia on its outside.

The two femoral condyles make up the rounded end of the femur. Its smooth articular surface allows the femur to move easily over the tibia. The knee joint is lined by synovium fluid which lubricates and nourishes the articular cartilage. Articular cartilage is the smooth covering at the ends of the femur and tibia. It is the damage to this surface which causes arthritis.

The patella is secured in place at the front of the knee by the quadriceps tendon and the patellar tendon. These connect to the upper and lower portion of the patella and allow the patella to move as the knee bends and straightens. The medial (inside) and the lateral (outside) meniscus are C-shaped layers of fibrocartilage which partially cover the surface of the tibia where it articulates with the femur. The majority of the meniscus has no blood supply and for that reason, when damaged, the meniscus is unable to undergo the normal healing process that occurs in the rest of the body. The menisci act as shock absorbers, protecting the articular surfaces of the tibia and femur. 

The anterior cruciate ligament (ACL) is the major stabilizing ligament of the knee. The ACL is located in the centre of the knee joint and runs from the femur to the tibia through the centre of the knee. The ACL prevents the femur from sliding backwards on the tibia - or the tibia sliding forwards on the femur. Together with the posterior cruciate ligament (PCL), the ACL stabilizes the knee in a rotational fashion. The medial (MCL) and lateral collateral (LCL) ligaments are found on either side of the knee joint. They minimize side-to-side movement and help to stabilize the knee.

Common Knee Injuries

Anterior Cruciate Ligament (ACL) ruptures are one of the most common serious sporting injuries. These can have a devastating influence on your activity levels, quality of life and long term knee health. A rupture occurs when there is a complete tear of the ACL. A partial injury can also occur, which can still be a significant knee injury.

The ACL plays a vital role in maintaining knee-joint stability, primarily through limiting anterior tibial translation on the femur and restraining rotation, but also by resisting varus and valgus forces at the knee.

An ACL tear can lead you to suffer functional instability and cause further damage to other critical structures in your knee. As a rupture or tear will not heal on its own, surgical intervention is often required to reconstruct your ACL.

How ACL tears occur :

There are two common causes of ACL tears: Non-Contact and Contact:

Non-contact: this is the most common cause of ACL injury and occurs without physical contact between individuals. This type of injury commonly occurs through a sudden deceleration or stopping, change of direction or valgus rotation when sidestepping or jump landing.

Contact: this occurs when there is involvement of an external force causing either hyper-extension or a valgus (twisting) moment in the knee.

  • Immediate swelling in the knee
  • Hearing a pop or crack at the time of injury
  • Giving way of your knee
  • Fear of twisting
  • Unable to fully straighten or bend the knee

Diagnosis is currently made through a combination of clinical examinations and investigations. This clinical examination involves a detailed subjective history on the mechanism of injury as well as clinical tests. Such tests may include the Lachman Test, the Pivot Shift and Anterior Draw.
An MRI is often required to confirm the diagnosis and to identify any other damage to the knee.

Non-surgical treatment

Majority of the time, a torn ACL will not heal without surgical intervention. Some patients may be able to undertake non-surgical management if they do not experience any instability (giving way) of their knee. However, without surgical intervention, your knee may remain unstable and you run the risk of causing severe damage to other critical structures in your knee.

Non-surgical management usually consists of a structured rehabilitation program often supervised by a physiotherapist. This can take between three and six months before you may be ready to return to sport. However, the timeframe may differ depending on the extent of the injury and your recovery process.

Amongst other factors, a patients age and activity levels are taken into account when deciding whether non-surgical management is the appropriate choice for somebody. For example, younger patients and people that intend to go back to pivoting and contact sports are often considered for surgical treatment.

Surgical Treatment

Surgical treatment involves reconstructing the ACL with a graft to restore knee stability.
The graft is commonly taken from either your patellar tendon – which is the tendon that runs between the kneecap and the shinbone – or the hamstring tendon from behind your knee.

If you have had previous ACL reconstruction, we may use your quadriceps tendon instead. This is the tendon that starts at the top of the knee cap and forms the quadriceps muscle group.

There can be pros and cons to all graft choices, all of which your surgeon will discuss with you prior to surgery.


Following surgery, you will need to undertake a significant period of rehabilitation. Your surgeon will provide you with a detailed rehabilitation program which will be broken down into different stages, each of which has a different purpose and goal.

It is expected that you will be completing three to four physio sessions per week throughout your rehab. Every patient’s recovery time is different, however, it is generally accepted that it can take between nine and twelve months following surgery to complete the appropriate rehab.

A meniscal tears is a common knee injury that often occurs following a twisting or turning movement.

In your knee, you have two menisci – the medial (inside) and lateral (outside) meniscus. They are a ‘C’ shaped cartilage located in between the bones of your knee and act as “shock absorbers” between your thighbone and shinbone. The purpose of the two menisci is to prevent the bones rubbing together and to maintain the stability of your knee.

Meniscal tears can occur in several different forms and are classified on both where the tear occurs and the shape of the tear. Some common tears that you may have heard of include Bucket Handle, Flap, and Radial. Meniscal tears will often happen at the same time as you injure other structures of your knee, such as your ACL.

  • Stiffness and swelling in the knee
  • Pain in the inside or outside of the knee
  • Catching or locking of your knee
  • Unable to fully straighten or bend the knee

Diagnosis is currently made through a combination of clinical examinations and investigations. The clinical examination involves a detailed subjective history on the mechanism of injury and clinical tests, including the McMurray test.
An MRI is often obtained to confirm the diagnosis and to identify other damage in the knee.


The treatment of meniscal tears differs and depends on the type of tear you have, its size, location and most importantly, your symptoms.

Non-surgical treatment

If your knee can still functioning without any locking, catching or pain, this may just be a small tear or one that is located on the outer edge of your meniscus and may not need surgical intervention.
Non-surgical treatment initially consists of rest and modifying your activity to restore full motion to the knee. Once you can move the knee, a low resistance stationary cycling program is essential and will require daily cycling for up to six weeks with a targeted knee strength program.

Surgical treatment

Surgery is often required in order to restore full function to the knee and different factors will be taken into account when deciding whether surgery is appropriate. Some of these factors are:

  • The size and complexity of the tear, such as a Radial or Bucket Handle tear;
  • Your age and whether you intend to return to sports; and
  • What symptoms you may have suffered following non-surgical treatment.

At UniSports, meniscal surgery is performed arthroscopically, which involves two small incisions being made to the knee. The surgeon then uses a small camera and surgical instruments through the incision sites to carry out the procedure.
Given the critical role the meniscus plays in the function of your knee, the goal of surgery is to repair the tear and to restore full function to the knee.

A meniscal repair involves using a surgical suture to stitch the torn pieces of meniscus back together. Whether or not this procedure can be undertaken depends on the nature and location of the tear which, unfortunately, often cannot be determined until the surgery is performed. After a meniscal repair, the tissue needs to heal, and you will have some restriction on what you can do following surgery.

In a number of cases, often due to the location and or size of the tear, a meniscal repair is not possible. In these instances, a partial meniscectomy is performed. This is a straightforward surgical intervention where the torn piece of meniscus is simply trimmed away and usually has a fairly quick recovery.


Following surgery, you will need to undergo a period of rehabilitation to restore the function and muscle strength around your knee. The timeframe and rehabilitation required will depend on what surgical procedure you have had. This information will be provided to you by your surgeon prior to surgery.

The expected recovery time following a meniscal repair is typical three to four months. However, with a partial meniscectomy, the recovery period is only around six to eight weeks.

The patella (kneecap) bone is shaped like a ‘V’ on its underside and sits in a valley shaped notch in the femur called the trochlear groove. The patella is supported in the groove by the surrounding ligaments and muscles of the knee. The shape and supporting structures of your patella ensure that when you bend and straighten your knee, the patella stays in place within the groove.
Patella instability occurs when it slips out of the groove and this typically results in the patella moving to the outside (lateral aspect) of your knee. Instability can occur as a subluxation (partial dislocation) or as a dislocation, which is when the patella comes entirely out of the groove.
Subluxations and dislocations will often self-relocate but occasionally will need to be relocated by a specialist. When the patella slips out of the groove, it can damage the ligaments and other supporting structures that help to hold it in place. Once these structures have been damaged, it can make it easier for the injury to occur again.

Causes of Patella Instability

There are several reasons instability of the patella can occur, some of which are simply genetic. Some common reasons are:
• a direct blow or a fall to the knee;
• being born with a shallow or narrow groove;
• being born with looser ligaments causing a higher degree of movement and flexibility in the joints and therefore making them prone to dislocations; or
• twisting around on a planted foot.


• Stiffness and swelling in the knee
• Pain
• Feeling of the knee slipping out
• Fear of twisting
• Fear of the knee giving way
• Unable to fully straighten or bend the knee


Diagnosis is made through a combination of clinical examinations and investigations. The clinical examination involves a detailed subjective history on the mechanism of the injury and clinical tests examining your range of movement and the ligament’s integrity.

An X-ray will be obtained to examine the position of the patella, often followed by an MRI to confirm the diagnosis and to identify whether there is any other damage in the knee.


For the majority of patients that have suffered their first instability episode, surgical intervention is often not required, and will just need non-surgical management.

Non-surgical treatment initially consists of modifying your activity and RICE (rest, ice, compression and elevation) to restore full motion to the knee and reduce pain and swelling. Once you can move the knee, a low resistance stationary cycling program and a targeted knee strength plan will be undertaken. Recovery timeframes will differ significantly between people but will usually range from six weeks to three months.

Surgical Intervention

Surgical intervention is usually required in the following instances:

  • if you have suffered several instability episodes (two or more);
  • if you are unable to return to activity following non-surgical management; or
  • if you have developed significant structural damage due to the patella moving out of place.

Surgery is aimed at restoring the stability of the patella and often involves repairing or reconstructing the ligaments that support it.

Following surgery you will often be in a knee brace for up to six weeks, which will restrict your movement and ability to weight bear. Once cleared by your surgeon, you will then start a functional rehabilitation program focusing on regaining movement in your knee, muscle strength and control.

The full recovery period following surgery typically can take between eight and ten months.

Other common knee injuries we treat

  • Medial collateral ligament (MCL) injuries
  • Lateral collateral ligament (LCL) injuries
  • Posterior cruciate ligament injuries
  • Multi ligament knee injuries
  • Articular cartilage injuries
  • Osteochondral injuries
  • Osteoarthritis

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