Introduction

Knee replacement surgery is a common and highly effective procedure that helps to ease pain and restore mobility in damaged knees. One question many patients ask is: what happens to the kneecap (patella) during the surgery? Some worry it might be removed entirely, but it’s important to know this is very uncommon. Instead, surgeons use different methods tailored to each person’s needs. In this article, we explain how the kneecap is managed during knee replacement, providing clear and reassuring information to help you understand the process.

The Role of the Kneecap in Knee Replacement

The knee joint consists of three main bones: the thigh bone (femur), the shin bone (tibia), and the kneecap (patella) at the front. The kneecap plays a vital role by protecting the knee and helping the muscles work more efficiently when bending and straightening the leg, such as when walking or climbing stairs. The condition of the kneecap is therefore an important factor influencing the success of knee replacement surgery.

When it comes to the kneecap during surgery, there are three main terms to understand:
Patellar resurfacing: replacing the worn surface of the kneecap with a smooth artificial implant.
Kneecap retention: keeping the kneecap as it is, without adding any prosthetic surface.
Kneecap replacement: rarely done, this involves completely replacing the kneecap with an implant.

Surgeons decide which option suits you best based on your individual condition. As one study points out, “geometry of the patella (kneecap) remains poorly understood yet is highly relevant to performing the correct patellar cut to reduce pain and to improve function and satisfaction after knee replacement surgery” (Rex et al., 2018). Visual aids like diagrams can help make these concepts clearer.

What Happens to Your Kneecap During Surgery?

There are three main approaches surgeons take regarding the kneecap during knee replacement:

1. Retention: The kneecap is left untouched if it’s healthy and shows little sign of arthritis.
2. Resurfacing: If arthritis has affected the kneecap’s surface, surgeons may replace that surface with a specialised plastic implant to reduce pain and improve joint movement.
3. Replacement: This is very rare and usually only considered in exceptional cases, such as severe injury.

The choice depends on several factors including your age, activity level, bone quality, and how badly arthritis has affected the kneecap. Fixing implants securely is vital in some cases.

Cutting the kneecap accurately during surgery is challenging. Research notes there is “significant variability between observers for this irregularly-shaped bone,” which means surgical skill and specialised tools are crucial (Rex et al., 2018). Ultimately, your treatment will depend on what suits your individual situation, supported by an expert and caring team throughout your recovery.

Retaining or Resurfacing the Kneecap: What Are the Outcomes?

Choosing whether to keep the kneecap as it is or to resurface it involves weighing several factors:

• Pain relief: Both options generally ease pain, but resurfacing may be more effective for some patients with front-of-knee pain.
• Function: Most patients regain good knee function regardless of the method, though results can vary.
• Risks: Resurfacing carries a slightly higher chance of complications like kneecap fracture or implant loosening.
• Satisfaction: Many patients are happy with their outcomes either way, especially when their care is personalised.

Measuring recovery after knee replacement is complex. A recent review found “49 different outcome measurements were used to evaluate clinical outcomes after knee joint replacement” with “no single patient-reported outcome measure used in more than half of the papers analysed” (Adriani et al., 2023). This highlights the variety in how success is assessed.

Recovery also depends on your rehabilitation. Promising new research shows that “training at home with customised exergames was more effective in mobility and early satisfaction” compared to standard exercise programmes, while being just as good at easing pain (Janhunen et al., 2023). This underscores the importance of a personalised rehabilitation plan. Remember, discussing your kneecap management and recovery plan with your surgeon helps ensure the best possible outcome.

Materials, Technology, and Expert Care

Materials used to resurface the kneecap are designed to be long-lasting and provide smooth movement within the knee joint. Surgical techniques and implant technology continue to improve, but expert judgement remains key to choosing what is best for you.

Professor Paul Lee, an experienced orthopaedic surgeon specialising in cartilage and joint preservation, advises closely on these matters and supports high standards of care. Centres like MSK Doctors offer professional, supportive environments for your treatment and rehabilitation, focusing on your individual needs.

Final Thoughts

If you are preparing for knee replacement surgery, it is important to ask questions and understand the options for managing your kneecap. Whether it will be retained, resurfaced, or rarely replaced is a decision made with your surgeon, based on your unique circumstances. Expert care and personalised rehabilitation are central to helping you achieve the best recovery. For more advice, speak with your consultant or seek out trusted patient resources.

Visual Aids Recommendation
Clear diagrams and infographics can make understanding your kneecap’s role in knee replacement much easier. These visuals help explain the surgical options and recovery steps, making the process less daunting and more transparent.

References

• Rex, E., Werle, J., Burkart, B., MacKenzie, J., Johnston, K. D., & Anglin, C. (2018). Shape Analysis of the Patellar Bone Surface and Cutting Plane for Knee Replacement Surgery. BioMed Research International, 2018, Article 6490425. https://doi.org/10.1155/2018/6490425
• Adriani, M., Becker, R., Milano, G., Lachowski, K., & Prill, R. (2023). High variation among clinical studies in the assessment of physical function after knee replacement: a systematic review. Knee Surgery, Sports Traumatology, Arthroscopy. https://doi.org/10.1007/s00167-023-07375-2
• Janhunen, M., Katajapuu, N., Paloneva, J., Pamilo, K., Oksanen, A., Keemu, H., Karvonen, M., Luimula, M., Korpelainen, R., Jämsä, T., Kautiainen, H., Mäkelä, K., Heinonen, A., & Aartolahti, E. (2023). Effects of a home-based, exergaming intervention on physical function and pain after total knee replacement in older adults: a randomised controlled trial. BMJ Open Sport & Exercise Medicine, 9(2), e001416. https://doi.org/10.1136/bmjsem-2022-001416