Patella Plural Form: Rule, Examples, and Mistakes

The plural form of patella is patellae (pronounced puh-TEL-ee). This follows the standard rule for Latin-derived medical nouns ending in -a, which change to -ae in the plural. In everyday clinical writing, you may also see patellas used as an anglicized alternative, but patellae remains the preferred form in formal medical contexts, anatomy textbooks, and professional documentation.

Quick Answer: Patella Plural

• Formal plural: patellae
• Informal plural: patellas
• Pronunciation: puh-TEL-ee (patellae); puh-TEL-uhz (patellas)
• Use in anatomy: Always patellae
• Use in conversation: Either is acceptable, but patellae sounds more precise

Why the Plural Rule Matters for Medical Writing

Medical English borrows heavily from Latin and Greek. The word patella comes directly from Latin, meaning a small pan or dish. In Latin, nouns ending in -a (first declension) form their plural by changing -a to -ae. This rule applies to many common medical terms: vertebra becomes vertebrae, conjunctiva becomes conjunctivae, and patella becomes patellae.

When you write a patient report, a research paper, or a referral letter, using the correct Latin plural signals that you understand medical terminology at a professional level. In less formal settings, such as an email to a colleague or a quick note in a patient chart, patellas is widely accepted and understood. The key is knowing your audience and the expected tone of the document.

Formal vs. Informal Contexts

Formal Tone (Academic Papers, Textbooks, Official Reports)

Use patellae. This is the standard in anatomy textbooks, surgical notes, and peer-reviewed journals. For example:

• The patellae were examined bilaterally for signs of fracture.
• Both patellae showed normal tracking during flexion.

Informal Tone (Emails, Casual Conversation, Quick Notes)

Use patellas. This is common in spoken language and informal written communication. For example:

• I noticed both of her patellas were slightly swollen.
• Can you check the alignment of his patellas on the X-ray?

Nuance to Remember

If you are writing for an international medical audience, patellae is safer because it is universally recognized in formal English. In British and American clinical settings, patellas is increasingly common in everyday use, but some senior clinicians or examiners may still expect the Latin form. When in doubt, use patellae for written work and patellas for spoken conversation.

Comparison Table: Patella Plural Forms

Natural Examples in Context

In a Patient Report (Formal)

The patient presented with bilateral knee pain. On examination, both patellae were tender to palpation, and there was mild crepitus during extension. No effusion was noted around either patella.

In an Email to a Colleague (Informal)

Hi Dr. Chen, I reviewed the X-rays you sent. The patellas look well-aligned, but I noticed some minor irregularity on the left. Let me know if you want to discuss.

In a Classroom Discussion (Mixed)

Remember that the patellae are the largest sesamoid bones in the body. When you palpate the patellas during an exam, check for mobility and tenderness.

In a Research Abstract (Formal)

We measured patellofemoral joint angles in 120 subjects. The patellae were categorized by shape using the Wiberg classification system.

Common Mistakes with Patella Plural

Mistake 1: Using “Patellae” as a Singular

Incorrect: The patellae bone is located in the knee.
Correct: The patella bone is located in the knee.
Why: Patellae is already plural. Use patella for the singular form.

Mistake 2: Adding an Apostrophe

Incorrect: Both patella’s were fractured.
Correct: Both patellae were fractured.
Why: Apostrophes indicate possession, not plurality. Never use an apostrophe to make a medical term plural.

Mistake 3: Mixing Forms in the Same Sentence

Incorrect: The patellae and the patella’s function are related.
Correct: The patellae and their function are related.
Why: Keep the plural form consistent throughout the sentence.

Mistake 4: Overcorrecting to “Patellae” in Casual Speech

Awkward: I hurt both my patellae when I fell.
Natural: I hurt both my patellas when I fell.
Why: In everyday conversation, patellas sounds more natural and less stiff.

Better Alternatives and When to Use Them

Sometimes you may want to avoid the plural form altogether. Here are alternatives that work in different contexts:

• Kneecaps – Use in very informal conversation or patient education. Example: Both kneecaps are stable.
• The patellar region – Use when referring to the area rather than the bone itself. Example: Examine the patellar region bilaterally.
• Each patella – Use when you want to emphasize individual assessment. Example: Each patella was examined separately.
• Patellar bones – Use in descriptive anatomy. Example: The patellar bones are sesamoid in nature.

When to use the formal plural: Always choose patellae in academic writing, exam answers, surgical reports, and any document that will be read by a formal audience. Choose patellas in emails, spoken language, and informal chart notes where clarity matters more than strict Latin grammar.

Mini Practice: Test Your Understanding

Choose the correct form for each sentence. Answers are below.

1. The surgeon examined both __________ before closing the incision.
   a) patella
   b) patellae
   c) patella’s
2. In her email, she wrote that the __________ appeared normal on the MRI.
   a) patellae
   b) patella’s
   c) patellas
3. Which sentence is correct for a formal research paper?
   a) The patellas were measured using calipers.
   b) The patellae were measured using calipers.
   c) The patella’s were measured using calipers.
4. During a casual conversation with a colleague, you say:
   a) Both patellae are tracking well.
   b) Both patellas are tracking well.
   c) Both patella are tracking well.

Answers:

1. b) patellae – This is a formal surgical context.
2. c) patellas – An email to a colleague is informal.
3. b) The patellae were measured using calipers – Formal writing requires the Latin plural.
4. b) Both patellas are tracking well – Casual conversation favors the anglicized form.

Frequently Asked Questions

1. Is “patellae” pronounced with a long or short “e” at the end?

The final “ae” in patellae is pronounced like a long “e” (EE). So it is puh-TEL-ee, not puh-TEL-eye or puh-TEL-ay. This is the standard medical pronunciation in both American and British English.

2. Can I use “patellas” in a medical journal article?

Most medical journals follow traditional Latin plurals for anatomical terms. Using patellas in a journal article may be seen as informal or incorrect. Always check the journal’s style guide, but patellae is the safer choice for publication.

3. What about the possessive form of patella?

The singular possessive is patella’s (the patella’s surface). The plural possessive is patellae’s (the patellae’s alignment). Avoid using patellas’ because the plural form patellas is already informal, and the possessive becomes awkward.

4. Do other bones follow the same -a to -ae rule?

Yes. Many bones and anatomical structures follow this pattern: vertebra (vertebrae), conjunctiva (conjunctivae), pleura (pleurae), and bursa (bursae). Learning this one rule helps you pluralize dozens of medical terms correctly.

Final Tip for Learners

The best way to master the plural of patella is to practice using it in both forms. When you write a formal note, force yourself to use patellae. When you speak with colleagues, let patellas come naturally. Over time, switching between the two will feel automatic, and you will sound both professional and natural in any setting.

For more guidance on medical plurals, explore our Plural Spelling Rules section, or check Common Plural Forms for other terms. If you have questions about specific words, visit our FAQ page or contact us directly.