Common Mistakes with the Plural of Patella

If you are writing about the kneecap in a medical context, the correct plural of patella is patellae. This follows the standard Latin plural rule for nouns ending in -a, which change to -ae. Using patellas is a common error, especially in informal writing or conversation, but it is not considered correct in formal medical or anatomical English.

Quick Answer: Patella Plural

Use patellae (pronounced puh-TEL-ee) for formal medical writing, academic papers, and professional reports. Use patellas only in very informal or conversational settings, and be aware that many readers or listeners may consider it a mistake.

Why This Confusion Happens

English speakers often apply regular plural rules (-s or -es) to Latin-derived medical terms. Since patella looks like a regular noun, adding -s feels natural. However, medical terminology preserves many Latin plural forms, and patella is a first-declension feminine noun in Latin, which takes the -ae ending.

Formal vs. Informal Context

In a formal context—such as a patient chart, a research paper, or a presentation to colleagues—you should always use patellae. In casual conversation with other medical professionals, you might hear patellas, but it is safer to stick with the correct form. In emails to a supervisor or in a clinical report, use patellae to maintain professionalism.

Comparison Table: Patellae vs. Patellas

Natural Examples

Here are examples showing how patellae and patellas appear in real writing and speech.

Formal Medical Report

“The patient presented with bilateral tenderness over both patellae. No swelling or erythema was noted.”

Academic Paper

“Fractures of the patellae are less common than those of the femur, but they require careful surgical planning.”

Casual Conversation (between colleagues)

“I saw two patients today with sore patellas—both from running too much.”

Note: In this last example, the speaker is using informal language. While it is common, a careful writer would still prefer patellae.

Patient Education Handout

“Your kneecaps (patellae) help protect the front of your knee joint.”

Here, the writer uses the correct plural but adds a plain English explanation for clarity.

Common Mistakes

Below are the most frequent errors learners and even native speakers make with the plural of patella.

Mistake 1: Using “Patellas” in Formal Writing

Incorrect: “The surgeon examined both patellas before the procedure.”
Correct: “The surgeon examined both patellae before the procedure.”

Mistake 2: Mixing Singular and Plural Forms

Incorrect: “One patella was fractured, but the other patellae was normal.”
Correct: “One patella was fractured, but the other patella was normal.” (or “Both patellae were normal.”)

Mistake 3: Mispronunciation

Some learners pronounce patellae as “puh-TEL-ay” or “puh-TEL-eye.” The standard pronunciation is puh-TEL-ee, with a long e sound at the end.

Mistake 4: Overcorrecting Other -a Nouns

Not all medical nouns ending in -a follow the same pattern. For example, stoma becomes stomata, not stomae. Be careful not to apply the -ae rule universally.

Better Alternatives and When to Use Them

If you are unsure about using patellae, consider these alternatives depending on your audience and context.

Use “Kneecaps” for General Audiences

When writing for patients or the general public, kneecaps is clear and avoids any plural confusion. This is especially useful in patient education materials, blog posts, or informal emails.

Example: “Both kneecaps were tender to the touch.”

Use “Patellar” as an Adjective

If you need to describe something related to the kneecap, the adjective patellar works well and avoids plural issues entirely.

Example: “Patellar reflexes were normal bilaterally.”

Use “Patellae” in Formal Contexts

Stick with patellae for academic writing, professional reports, and any situation where precision and adherence to standard terminology matter.

Mini Practice Section

Test your understanding with these four questions. Answers are provided below.

Question 1

Which sentence is correct for a medical journal?

A) The patient had swelling in both patellas.
B) The patient had swelling in both patellae.

Question 2

Fill in the blank: “The radiograph showed a fracture of the left patella and a dislocation of the right __________.”

Question 3

True or False: Using patellas is always incorrect in English.

Question 4

Rewrite this sentence for a formal report: “The doctor checked both kneecaps and found no problems.”

Answers

Answer 1: B) Patellae is the correct plural for formal writing.

Answer 2: Patella (singular) or patellae (if referring to both). The sentence mentions “the right” patella, so the singular form is correct: patella.

Answer 3: False. Patellas is used in informal contexts, but it is not standard in formal medical English.

Answer 4: “The physician examined both patellae and found no abnormalities.”

Frequently Asked Questions

1. Is “patella” singular or plural?

Patella is singular. It refers to one kneecap. The plural is patellae.

2. Can I use “patellas” in an email to a doctor?

It depends on the formality of the email. In a professional email to a colleague or supervisor, use patellae. In a very casual message to a friend who is also a medical professional, patellas might be understood, but it is still better to use the correct form.

3. How do you pronounce “patellae”?

Pronounce it as puh-TEL-ee. The final -ae sounds like the ee in see.

4. Are there other medical words like “patella” that change to “-ae”?

Yes. Common examples include vertebra (plural vertebrae), conjunctiva (plural conjunctivae), and bursa (plural bursae). Learning these patterns helps you avoid mistakes with many medical terms.

For more guidance on similar plural forms, visit our Confusing Plurals section. You can also check Plural Spelling Rules for a broader understanding of how medical plurals work. If you have further questions, see our FAQ or contact us.