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Pathology · patient case question

What does the additional 5 mm of opening on passive stretch, with pain at the end of that range, indicate?

Patient case: Restricted opening with pain only on passive stretch

Patient: Female, 33 years old

Chief Complaint: “My jaw feels tight and I cannot open as wide as I used to.”

Background: Reports a stressful year and daytime clenching. No trauma, no locking episodes, no previous treatment.

Vital Signs: BP 116/72 mmHg · HR 76 bpm

Findings: Maximum comfortable opening 32 mm. On gentle PASSIVE STRETCH the jaw opens a further 5 mm, at which point the patient reports pain. NO pain on lateral or protrusive movements. NO joint noise. Palpation of the masseter and temporalis reproduces her familiar discomfort. Radiographs show no degenerative change.

  1. Anterior disc displacement without reduction on the left
  2. A MUSCULAR restriction — the soft end feel of muscle guarding
  3. Degenerative joint disease of the condyle
  4. Anterior disc displacement without reduction on the right
Show answer and explanation

Correct answer: B. A MUSCULAR restriction — the soft end feel of muscle guarding

  • A. The same reasoning applies whichever side is proposed. The end feel is soft, so the block is not intracapsular.
  • B. CORRECT. The END FEEL is what the test is for. If gentle passive stretch gains a further 4–5 mm before pain, the restriction is SOFT and springy — muscle, which stretches under load. That points to MYALGIA or protective guarding, and it fits the rest of the picture: palpation reproduces her familiar pain, there is no joint noise, and lateral and protrusive movements are painless.
  • C. Degenerative joint disease produces crepitus, radiographic flattening, erosion or osteophyte formation, and pain on loading. None is present.
  • D. A disc displaced without reduction gives a HARD end feel — passive stretch gains little or nothing, because the displaced disc mechanically blocks translation. It also produces persistent deviation toward the affected side and pain on contralateral excursion.

Note: The bedside distinction to carry: a SOFT end feel with several extra millimetres on stretch means MUSCLE; a HARD end feel with no give means DISC or bony ankylosis. Normal maximum opening is 40–55 mm, and translation contributes the portion beyond roughly 25 mm — which is why muscular and disc restrictions both show up in the 25–35 mm range.

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