A successful total knee replacement is about more than pain relief. For many patients, comfortable movement depends on how smoothly the kneecap glides in its groove after surgery. That groove is called the trochlea. A recent study in JISAKOS co-authored by Dr Jobe Shatrov asked a simple question with important consequences: does a common surgical technique reliably restore the trochlear groove so the patella tracks well?

Read the full paper: https://www.jisakos.com/article/S2059-7754(24)00211-6/fulltext

Why the trochlea matters to your new knee

The trochlea is the shallow channel at the end of the thigh bone where the kneecap sits and slides as you bend and straighten the knee. If this sliding pathway is off, the kneecap can feel like it is catching or drifting to one side. Patients may notice pain when standing from a chair, going downstairs, or kneeling. Good trochlear alignment supports smooth patella tracking, lower pain, and better function.

The traditional surgical assumption

For years, many surgeons have been taught that if the metal component on the thigh bone is placed “flush” with the front surface of the femur, the new trochlear groove should line up well with the native anatomy. This approach is simple and reproducible. The question is whether it works consistently across different femur shapes and sizes.

What the study set out to test

The research team examined how closely this “flush with the anterior femoral cortex” technique restores the position and angle of the trochlear groove. In practical terms, they wanted to know whether a commonly used method gives the kneecap a pathway that truly suits the individual patient, or whether there are cases where the groove ends up slightly off to the side or at an angle that makes tracking less predictable.

How the researchers approached the problem

Rather than focusing on one implant or a single type of knee, the study evaluated the relationship between component placement and the resulting trochlear alignment using accepted anatomical measurements. The analysis compared where the groove ended up relative to key bony landmarks that guide patella movement. The goal was to quantify how often the traditional technique aligned well, and how often it produced a meaningful deviation.

You do not need to know the mathematical details to understand the message. The team measured alignment accurately, then asked a clinical question: does this technique recreate a trochlear groove that gives the kneecap the best chance to track centrally and comfortably?

What the study found

The headline finding is that placing the femoral component flush with the front of the femur does not always reproduce the patient’s native trochlear groove. In some knees, the groove ended up shifted laterally or orientated at an angle that could influence patella tracking. Small differences can matter when it comes to kneecap comfort, especially during activities that load the patellofemoral joint, such as stairs or squatting.

In other words, a one-size-fits-all method may work for many patients, yet it can miss the mark for others whose bony anatomy is slightly different. The study supports a more individualised approach to aligning the femoral component, with greater attention to where the reconstructed trochlear groove will guide the kneecap.

What this means for patients

For patients considering total knee replacement, this research highlights why surgical planning and technique are so important to everyday comfort after surgery. Correct alignment of the femoral component helps the kneecap track centrally. When the patella tracks well, people often report less grinding, fewer catching sensations, and better confidence on stairs or uneven ground.

This does not mean that traditional techniques are unsafe or that most replacements will have tracking problems. It means your surgeon considers several alignment strategies rather than relying on a single rule. The aim is to position your components to suit your anatomy, not an average knee.

Where modern tools fit in

Advanced planning and intraoperative technologies, including computer navigation and robotic assistance, can help surgeons visualise how different component positions change the reconstructed trochlear groove. These tools are not a guarantee of perfect tracking. They are decision aids that allow finer adjustments and verification during surgery.

Patients often ask whether robotic systems “fix” kneecap problems. Robotic guidance can improve consistency in bone cuts and component placement. Patella tracking is multifactorial and depends on soft tissues, implant design, and component alignment together. The value of technology comes from helping the surgeon tailor alignment to the individual knee.

Frequently Asked Questions

Will I feel the kneecap catching after a knee replacement?
Most patients do not. If patella tracking is not ideal, symptoms can include a sense of rubbing or clicking, especially with stairs. Careful planning and rehabilitation reduce this risk.

Does everyone need their kneecap resurfaced?
Not always. Resurfacing the patella is a separate decision from femoral component alignment. Your surgeon considers cartilage quality, implant design, and your symptoms to decide what is best.

Can physiotherapy help with patella tracking after surgery?
Yes. Strengthening the quadriceps and hip muscles, improving mobility, and retraining movement patterns all support the kneecap. Rehabilitation works alongside accurate surgical alignment.

Is robotic knee replacement better for the kneecap?
Robotic assistance can improve the accuracy of component positioning. Good tracking still relies on the overall plan, implant choice, and soft-tissue balance.

How Dr Shatrov applies this evidence

Dr Shatrov integrates current research into pre-operative planning and intraoperative decision-making. The aim is to restore a stable, well-aligned joint while giving the patella a central, smooth pathway. This means:

• Analysing your anatomy and alignment in detail during planning

• Considering how femoral component position will shape the trochlear groove

• Using technology when it adds value for precision and verification

• Coordinating rehabilitation to support patellofemoral function

Key takeaways

• The trochlear groove guides the kneecap. Its position after knee replacement affects comfort during everyday activities.

• A traditional “flush with the bone” technique does not always recreate the native groove. Some knees need more tailored alignment.

• Modern planning tools and careful soft-tissue balancing help surgeons individualise component placement for better patella tracking.

• Rehabilitation remains essential. Strong, well-coordinated muscles support a centrally tracking kneecap.

Read the full paper: https://www.jisakos.com/article/S2059-7754(24)00211-6/fulltext

Learn more

• Total and partial knee replacement (insert internal link)

• Robotic knee surgery (insert internal link)

• Patella instability and dislocation (insert internal link)

• About Dr Jobe Shatrov (insert internal link)