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If you’ve heard of OCD, chances are, you’ve heard of the psychological condition, rather than the musculoskeletal condition. Whilst we do, in our humble opinion, think we can more than handle ourselves with most conditions that walk through our doors, we can’t quite claim to help with the psychological OCD. So, let’s talk about the other OCD, the one that’s more relevant to us at Spectrum: Osteochondritis Dissecans.

Your knee is the largest hinge joint in the body, connecting the thigh bone (femur) to the shin bone (tibia), with the kneecap (patella) sitting in front for protection. The outer layer of these bones are covered in an articular cartilage, which allows for smooth movement and absorbs shock during activities like walking, running, or jumping. Beneath this cartilage is the subchondral bone: a supportive layer that provides structure and nourishment to the cartilage. Underneath this subchondral bone, is cortical bone and then trabecular bone to round out the layers. Osteochondritis dissecans occurs when a small segment of the subchondral bone, along with its overlying cartilage, loses its blood supply in a process called avascular necrosis. In the knee, this process most commonly affects the medial femoral condyle, which is on the inner aspect of the knee. Whilst there are other locations where avascular necrosis may occur in the body, OCD most commonly occurs in the knee.

How and Why Does OCD Happen?

In truth, we don’t completely know the reason that this injury can occur. Our best theory for the time being is that it is a repetitive overuse process. In essence, repetitive impact micro-trauma to the medial compartment (inner side) of the knee from activities such as jumping, running and pivoting often, can disrupt blood flow to the subchondral bone. This is termed ischaemia, where the bone is starved of nutrients by way of a diminishing blood supply. Long-term exposure to ischaemia, plus continued load can lead to complete severance of this blood supply, making the tissue avascular, or having no blood supply. At this stage, tissues begin to die, and that is famously called necrosis. Along the sequence of the bone weakening and losing its nutrients, a small piece can crack, separate or break loose. This entire pathological sequence is termed osteochondritis dissecans.

Following the same vein of thought, aberrant mechanics can contribute to this repetitive impact over-loading and micro-trauma. In the hips, weak gluteal muscles or tight adductor muscles can affect the angle the femur articulates inside the acetabulum (hip joint), or articulates at the knee. Varus forces place more pressure at the medial aspect of the knee and can contribute to OCD developing. Looking at the ankle, excessive inversion due to flat feet or ankle instability can similarly cause varus loading at the medical compartment of the knee. And finally, the knee itself can be the root cause of how OCD develops. There is a strong link between OCD and childhood obesity, where the added weight to growing bones and developing joints can interrupt blood flow. In each case, excess stress, whether via varus force or direct loading, affecting the medical compartment of the knee is the common denominator. When observing who this injury commonly affects, it is much more prevalent in adolescent males than females. This may be due to their greater uptake of high impact sports, such as football or basketball, where this repetitive microtrauma occurs. OCD is also seen more commonly in the aging population, where there is a higher prevalence of vascular issues and arthritic or bone deconditioning diseases.

What Does OCD Feel Like?

So far that all sounds pretty alarming, necrosis and tissue death isn't a pleasant topic, but we must reiterate that OCD is a rare condition! Symptoms are quite reminiscent of various other potential injuries. For that reason, rely on our expert Spectrum staff who are trained to assess complex knee injuries for diagnosis. Symptoms include:

• Knee joint pain: typically worsening with activity and improving with rest.
• Knee stiffness: especially after periods of inactivity, making movement feel restricted.
• Swelling or tenderness around the joint: is common, as the loose fragment can irritate surrounding tissues.
• Mechanical symptoms: in some cases, a 'catching' or 'locking' sensation occurs, where the joint feels like it's stuck due to the loose fragment interfering with normal motion. Clicking or popping sounds during movement may also be noticeable.

OCD is inside the joint, at the level of the bone. Whilst necrosis can affect surface level tissues, remember OCD is only referring to the knee joint. You won't see any direct skin changes like in the movies, which I'm sure is where your mind went to when you first read 'necrosis'. In light of this, to rule OCD in or out as a diagnosis, we typically do need to see below skin deep.

Imaging

There are a few options that we can employ to look for OCD, let's take a look:

• Magnetic Resonance Imaging (MRI): At Spectrum, if we suspect a major knee injury or process is occurring, particularly with mechanical symptoms such as locking, catching and clicking, we typically refer for MRI imaging. MRIs are great for visualising oedema (inflammation), and bone vascular changes which are present in OCD. They can also detect bony changes such as fractures and overall bone health, which are critical to analyse in these cases. Therefore, our first point of call would generally be an MRI.
• X-ray: These are also useful, but typically only towards the more advanced end of avascular necrosis where there is a loose body or bone fragment which has separated from the main femur.
• Computed tomography (CT): might be used for precise bone assessment or to detect loose bodies, but it's less common as if we would generally look towards an MRI for more detail in this case.

As we touched on above, there is a pathological process to OCD before we reach the final stage of avascular necrosis and fracture of the medial femoral chondyle. We classify OCD into stages based on stability: from early changes where the bone is intact but weakened (stage I), to advanced stages where the fragment detaches completely (stage III and IV). There's also a distinction between juvenile OCD (in children with open growth plates) and adult OCD (in those with closed growth plates).

How Can Spectrum Help You?

When OCD comes into our clinic, we do have an armoury of non-surgical treatment options that can help you. Despite the alarming diagnosis, stable OCD in children and adolescents can heal conservatively. As children typically have better blood flow than us adults, the juvenile form of OCD can have better outcomes. Here's how we'd help with the healing process:

• Immobilisation: a brace can be fitted which holds the knee in a neutral position for 4-6 weeks in the initial phase.

• Rest and Activity Modification: avoiding high-impact activity with possible use of crutches for partial or non-weight-bearing to offload the knee in the initial phase.

• Pain management: manual therapies, such as dry needling, soft tissue massage, cupping, joint mobilisation and many more, are options to help you manage symptoms. In addition, we can use our advanced technology available to us, for example the Game Ready hot and cold contrast system, which blends the advantages of heat, cold and compression therapies.

• Rehabilitation: targeted exercises to strengthen the knee, ankle and hip muscles after immobilisation and rest period are vital to returning to normal function. We have great technology to help us in this area of recovery too: our Alter G anti-gravity treadmill is the perfect solution to returning to full weight-bearing, walking and running for our young athletes.

• Referral: if conservative care fails, or the lesion is unstable / large, advanced options come into play. Injections aren't a primary treatment for OCD but can help.  Corticosteroids may help to reduce inflammation and pain temporarily. Hyaluronic acid can assist in joint lubrication to ease stiffness, and PRP may help to promote healing in stable lesions. Further to this, surgical opinion may be warranted, where the loose body may be reattached to the femur, or the cartilage may need to be addressed. In either case, whether it can be managed conservatively or it needs some assistance, Spectrum can help point you in the right direction.

If left untreated, OCD has been linked with early onset osteoarthritis, further joint pain and loss of function. Prompt assessment, diagnosis and treatment is essential for best outcomes.