How does your knee work?
Your knee is one of the most complex joints in your body.
It consists of three bones: the bottom of the thigh bone (femur), the top of the shin bone (tibia), and the kneecap (patella) at the front.
The most important is the joint between the femur and tibia, held together by four major ligaments, one of which is the anterior cruciate ligament (ACL).
ACL Tears.
What is the ACL’s function?
The ACL primarily keeps the femur and tibia aligned when an athlete changes direction (pivoting). Pivoting is the most common cause of ACL ruptures, with female athletes being particularly vulnerable.
A ruptured ACL can trigger a chain reaction of damage in your knee.
When an athlete ruptures their ACL, the femur and tibia fall out of alignment, placing abnormally large forces through other structures in the knee.
These structures can also be damaged, including the shock-absorbing cartilage rings (meniscus), other ligaments such as the medial collateral ligament (MCL), and the tough covering on the ends of the bones (articular cartilage).
What treatment works best?
An ACL tear is one of the most disruptive knee injuries, often requiring surgical reconstruction to restore the stability needed for certain movements and sport. Where no surrounding structures are damaged, rehabilitation can sometimes be enough to return to daily activities.
Non-operative treatment
Athletes with an isolated ACL injury (no other structures damaged) can achieve good knee function without surgery through a dedicated rehabilitation program. Range of motion and strength can return to normal and straight-line running can recover.
Surgery
Most athletes who want to return to pivoting sports, or who have also damaged other structures, are typically advised to have early reconstructive surgery. Unless repaired, meniscus and cartilage injuries can lead to chronic knee pain and eventual arthritis. To successfully repair these lesions, surgery should be performed soon after injury, with the ACL reconstructed at the same time to protect the other repaired structures.
How is the ACL Reconstructed?
When the ACL completely tears, stability and strength can’t be reliably restored by stitching it back together. Instead, the ACL must be reconstructed. This involves creating a new structure that mimics the ACL and securing it inside the knee where the original used to be. The best results come from using tendons or ligaments from your own body. The tissue chosen to reconstruct the ACL is called a graft.
Several graft options are available, each with benefits and drawbacks. If you need ACL reconstruction, Dr Bell will suggest the best graft for you based on your unique situation and goals.
ACL reconstruction is generally a highly successful operation.
With dedication to post-operative rehabilitation, most patients return to the same level of sport they played prior to injury.
Meniscus Tears.
How does your meniscus work?
Between your thigh bone and the top of your shin bone are two C-shaped cartilage rings (menisci). They're responsible for absorbing weight and helping to keep your knee stable.
A torn meniscus can be painful, and fragments can move to where they shouldn't be in the knee.
This can cause a locking or catching sensation. The knee can also give way.
Meniscus tears can occur in an otherwise healthy knee or, often, in association with ligament injuries. Typically, we see them in athletes who put high loads through their knee. The quality of the tissue and pattern of the tear often determine whether the meniscus can be surgically repaired.
What treatment works best?
Tears in a healthy knee can often be surgically repaired, while surgery for patients with arthritis is usually ineffective. I’ll work with you and your care team to determine the treatment that’s best for you.
Cartilage Injuries
What is a cartilage injury?
Where your thigh bone, shin bone, and kneecap meet, they're covered with a tough, shock-absorbing tissue called articular cartilage. This cartilage can be damaged in two ways. Most commonly, widespread cartilage wear, otherwise known as arthritis. The other is a discrete lesion, often sustained when playing sport.
Discrete lesions are like a pothole on an otherwise smooth road.
They may occur in isolation, or alongside other knee injuries such as ligament or meniscus damage. These lesions can cause pain, swelling, and mechanical symptoms such as a catching or locking sensation.
What treatment works best?
Most patients can improve with a dedicated, non-operative rehabilitation program supervised by a physiotherapist. For some, symptoms can persist and surgery may be the best option. Several surgical techniques are available to restore the damaged cartilage. Dr Bell will recommend the most suitable technique based on the size and location of the lesion and your athletic goals.
Patella Instability.
How does your patella work?
Your kneecap glides in a groove at the end of your thigh bone as your knee bends and straightens. Like a train running along its tracks.
The quadriceps tendon attaches at the top of your kneecap, and the patella tendon extends from the bottom, connecting it to the front of your shin bone. The quadriceps and patella tendons act like the engine and connectors keeping the kneecap on track.
Patella instability occurs when your kneecap shifts sideways out of the groove, like the train coming off the tracks.
This generally happens when the tendons aren’t pulling the kneecap in line with the groove. It can also happen when the groove is too shallow to keep your kneecap on track.
What treatment works best?
For most patients, the first step is a strengthening program prescribed by a physio or exercise physiologist. If your kneecap remains unstable after this, surgery may be recommended. If surgery is required, I’ll perform a thorough assessment including advanced imaging to identify the cause of your instability. I will then recommend the most appropriate procedure for you.
Knee Arthritis.
Understanding the anatomy of your knee.
Your thigh bone, shin bone, and kneecap meet in three areas of your knee (called compartments), covered with a smooth, slippery, and tough tissue called articular cartilage.
The end of your thigh bone is shaped like two knuckles side by side. These knuckles contact the relatively flat surface of your shin bone, creating two compartments: the medial (closest to your body’s midline) and lateral (farthest from your body’s midline). The third contact area is between your kneecap and the front of your thigh bone.
Arthritis (joint inflammation) commonly affects the knee, causing it to become painful, stiff, and swollen.
Articular cartilage slowly wears away, creating a rough surface and exposing underlying bone to stress. Eventually, the cartilage can wear away completely, causing your bones to rub against each other.
Arthritis, most commonly caused by osteoarthritis, is generally a disease of aging. It can occur in younger patients (particularly after serious knee injuries like ligament tears and fractures). For older people, the primary cause is genetic, with occupation, obesity, and muscle weakness being additional risk factors.
Most people get osteoarthritis in both the medial and lateral compartments, with pain affecting the whole knee. For some patients, it primarily affects one compartment, with their pain localised to one side of their knee.
What treatment works best?
Despite their best efforts, researchers are yet to find an effective treatment to restore articular cartilage once it has worn. Current treatments aim to minimise symptoms and slow the progression of further wear.
Non-operative treatment
It may seem counterintuitive, but staying physically active is one of the most important treatments. Low impact activities like walking, cycling, swimming, and light strength training (under the guidance of a physio or exercise physiologist) can be extremely helpful. It helps maintain movement and strength in your knee.
Surgery
If non-operative measures fail to control your symptoms and pain persists with daily tasks like walking, climbing stairs, or sleeping, surgery may be recommended. For most patients, knee replacement is the most reliable operation to relieve pain and improve function. Approximately 90% of patients achieve a good result.
What’s involved in a knee replacement?
A knee replacement involves removing the worn-out bone ends, including the remaining cartilage and some underlying bone. Metal caps are then placed on the cut bone surfaces, with a tough plastic (polyethylene) implant between them to form a new joint.
For the best results, the precise amount of bone and cartilage must be removed, and the replacement implanted in exactly the right position to restore your knee as closely as possible to its natural state.
Before surgery, Dr Bell will take specific X-rays to assess the natural alignment and bone structure of your knee. The surgery is then performed with a robotic assistant, helping Dr Bell remove the precise amount of bone to carry out the surgical plan.
A knee replacement is considered major surgery.
You’ll need to stay in hospital for at least two to three nights after surgery to ensure your pain is well controlled and you can move safely with walking aids. While you’re in hospital, a physio will help with your mobility and guide you through exercises to get your knee moving and your muscles working again.
With the right preparation and support, most patients can go straight home from hospital, with at-home pain management. You’ll be guided on how to manage everyday tasks at home like bathing, getting dressed, and getting in and out of a car.
You’ll have a wound dressing on your knee that needs to stay dry and intact until I review you at my clinic, two weeks after surgery. By this point, most patients have healed enough to get the wound wet in the shower. For pool work (hydrotherapy), I generally recommend waiting four weeks after surgery to ensure the wound has sealed completely.
You won’t be able to drive until you can safely operate the accelerator and brake. This generally takes six weeks, though it may be sooner for automatic cars when the left knee is operated on.
1-2 weeks:
Your knee will still be painful and swollen. You’ll need ongoing icing and compression, regular paracetamol, and anti-inflammatory and opioid (morphine-like) medication as needed. A walking aid will still be required (your physio will advise on this).
2-6 weeks:
Swelling and pain begin to settle and your range of motion improves. You’ll still need paracetamol but less opioid medication. Mobility improves, with some patients managing short distances around the house without a walking aid.
6-8 weeks:
Swelling is significantly reduced but still present. Most patients are moving around the house without a walking aid, with pain well controlled on paracetamol alone. You can return to driving and office-based work.
12-16 weeks:
Swelling and pain are minimal. You won’t need a walking aid and will be regaining your independence, including returning to light manual work or gardening.
Long-term:
Staying committed to your exercises will continue to improve movement and strength for up to a year after surgery. A weights-based gym program will achieve the best results, improving your walking pattern, ability to get out of a chair, navigate stairs, and walk longer distances.
Let’s get you moving like yourself again.
Whether you need a diagnosis, a second opinion, or a clear treatment plan, we’re here to help.
