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User: radiographic findings is

radiographic findings is consistent with dorsal intercalated segment instability (DISI)ممكن تشرح وتنزل وتجيب صور كثيرة

Assistant: !https://www\.researchgate\.net/profile/Jonny\-Andersson/publication/319937516/figure/fig2/AS%3A540741919559680%4015059…

!https://www\.researchgate\.net/profile/Jonny\-Andersson/publication/319937516/figure/fig2/AS%3A540741919559680%401505934328078/Dorsal\-intercalated\-segment\-instability\-DISI\-with\-a\-scapholunate\-angle\-of\-approximately\_Q640\.jpg !https://www\.medical\.theclinics\.com/cms/10\.1016/j\.mcna\.2014\.04\.003/asset/60d34e96\-d732\-48d4\-acd8\-915ab709ac0b/main\.assets/gr8\_lrg\.jpg !https://data\.pacs\.de/sites/default/files/mirrorimages/media\.springernature\.com/full/springer\-static/image/art%253A10\.1007%252Fs13244\-014\-0337\-1/MediaObjects/13244\_2014\_337\_Fig3\_HTML\.gif !https://image\.slidesharecdn\.com/20150914stafflectureupperext\-150913143227\-lva1\-app6891/95/emergency\-radiology\-shoulder\-upper\-extremities\-70\-638\.jpg?cb=1442154947

يا محمد، لما يقول لك السؤال: “radiographic findings consistent with DISI” فهو غالبًا يريد منك “تلتقط” ميل الـ lunate للخلف (dorsiflexion) على lateral wrist radiograph وتثبت ذلك بالأرقام والزوايا الكلاسيكية.

DISI = Dorsal Intercalated Segment Instability

• “Intercalated segment” المقصود بها lunate (تُعتبر قطعة “وسطية” بين radius وcarpus).
• في DISI: الـ lunate تميل dorsally (extension/dorsiflexion) لأن التوازن الرباطي اتكسر غالبًا بسبب Scapholunate ligament injury → scaphoid يميل للـ flexion بينما lunate تُسحب للـ extension مع triquetrum/capitate.

المسبب الأشهر:

• Scapholunate ligament injury (خصوصًا بعد FOOSH) وهو المصدر الأكثر كلاسيكية لــ DISI. orthobullets.com

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لازم تكون الصورة true lateral (ده فخ امتحاني: لو الـ lateral غلط الزوايا كلها هتضرب).

1. Scapholunate angle (SLA) مرتفع

• الطبيعي تقريبًا 30° إلى 60°.
• في DISI: غالبًا SLA أكبر من 70° (وهي عبارة امتحانية صريحة جدًا). orthobullets.com

1. Radiolunate angle (RLA) مرتفع

• في DISI يحدث dorsal tilt of the lunate ويظهر كـ RLA أكبر من 10°. Radiopaedia

1. Capitolunate angle (أو Lunocapitate angle) مرتفع

• كثير من المراجع تذكر Capitolunate angle أكبر من 30° كداعم قوي للـ DISI. PMC

1. Scapholunate gap widening

• “Terry Thomas sign” (زيادة المسافة بين scaphoid وlunate).
• أحيانًا تحتاج stress views مثل clenched fist view لإظهار الـ widening إذا كانت الإصابة ديناميكية. pubs.rsna.org

1. Scaphoid ring sign

• نتيجة scaphoid flexion/rotary subluxation (حلقة/دائرة واضحة في scaphoid على PA).

- ليست كل زيادة في SLA = DISI إذا كانت اللقطة ليست true lateral أو كان المعصم في وضع غير neutral. PMC

• DISI قد تكون dynamic: PA طبيعي تقريبًا لكن تظهر بالـ clenched fist أو ulnar deviation stress. pubs.rsna.org
• فرّق بين DISI و VISI: - DISI عادة مع Scapholunate ligament injury - VISI عادة مع Lunotriquetral ligament injury (وهنا lunate تميل volarly). PMC

- لو الأشعة مش واضحة والشك عالي: - اعمل stress views (clenched fist). pubs.rsna.org - وMRI / MR arthrogram لتقييم Scapholunate ligament خصوصًا في الإصابات الحادة/قبل الجراحة. pubs.rsna.org

إذا تحب، ابعتلي صورة السؤال/الأشعة اللي عندك (خصوصًا الـ lateral)، وأنا أمشي معك خطوة بخطوة: هل هي true lateral؟ وهل الزوايا داخلة في DISI ولا في perilunate/lunate dislocation (لأن دي برضه أسئلة شائعة وتتلخبط بسهولة).

gpt-5-2

User: ممكن تعيد بالانجليزي

ممكن تعيد بالانجليزي

Assistant: !https://prod\-images\-static\.radiopaedia\.org/images/30733038/986af30d0ca20e140b04cf5487c016\big\gallery\.jpeghttps:/…

!https://prod\-images\-static\.radiopaedia\.org/images/30733038/986af30d0ca20e140b04cf5487c016\_big\_gallery\.jpeg !https://www\.researchgate\.net/profile/Ahmed\-Elsaftawy/publication/256452003/figure/fig5/AS%3A314936254320644%401452098062635/n\-case\-of\-rotary\-subluxation\-of\-the\-scaphoid\-scapholunate\-angle\-60\-lunate\-capitate\_Q320\.jpg !https://upload\.orthobullets\.com/topic/6041/images/gw275h550\.\.jpg 5

Radiographic Findings Consistent with DISI (Dorsal Intercalated Segment Instability)

1) What does DISI mean?

DISI is a pattern of carpal instability in which the lunate tilts dorsally (extends) on the lateral wrist radiograph. It occurs most commonly after Scapholunate ligament injury. Mechanism in brief:

• Scaphoid loses its stabilizing link to the lunate → scaphoid collapses into flexion
• Lunate, pulled by the triquetrum and capitate, rotates into extension (dorsiflexion)

2) Key Radiographic Findings (High-yield for exams)

A) Lateral view (the most important view)

The diagnosis of DISI is primarily made on a true lateral wrist radiograph.

1. Dorsal tilt of the lunate

• The lunate’s distal articular surface faces dorsally
• Often described as the lunate “cup” opening posteriorly

1. Increased Scapholunate Angle (SLA)

• Normal: approximately 30°–60°
• DISI: typically greater than 70°
• This is the single most quoted numeric criterion in exams

1. Increased Radiolunate Angle (RLA)

• Normal: near neutral
• DISI: greater than 10°, reflecting dorsal lunate tilt

1. Increased Capitolunate (Lunocapitate) Angle

• Normal: less than 30°
• DISI: greater than 30°, indicating loss of collinearity between lunate and capitate

Classic exam phrase:

“DISI on lateral view is characterized by dorsal lunate tilt with an increased scapholunate angle, usually greater than 70 degrees.”

B) PA (posteroanterior) view – supportive findings

PA views help identify the cause, not the alignment itself.

1. Scapholunate gap widening

• Increased distance between scaphoid and lunate
• Known as the “Terry Thomas sign”

1. Scaphoid ring sign

• Seen due to scaphoid flexion and rotary subluxation

1. Dynamic instability

• Early DISI may have a normal PA view
• Widening appears only on stress views such as: - Clenched fist view - Ulnar deviation stress view

3) How to Measure (Practical Exam Technique)

On a true lateral radiograph:

• Draw the long axis of the scaphoid
• Draw the axis of the lunate → angle between them = Scapholunate angle
• Draw the radius axis and lunate axis → Radiolunate angle
• Draw the capitate axis and lunate axis → Capitolunate angle

If the lateral is not perfectly true, angles are unreliable (important pitfall).

4) Common Pitfalls (Frequently Tested)

• False DISI can be diagnosed if the lateral view is rotated or not neutral
• DISI vs VISI: - DISI → dorsal lunate tilt → Scapholunate ligament injury - VISI → volar lunate tilt → Lunotriquetral ligament injury
• Early DISI can be dynamic, visible only with stress imaging

5) Why DISI Matters Clinically (Exam Progression)

Untreated or chronic DISI commonly progresses to:

• SLAC wrist (Scapholunate Advanced Collapse)
• Predictable pattern of degenerative arthritis

This progression is a very common MCQ concept.

6) If X-rays Are Inconclusive

Next diagnostic steps may include:

• Stress radiographs
• MRI or MR arthrogram to assess the Scapholunate ligament
• Wrist arthroscopy (gold standard in equivocal cases)

One-line exam summary

DISI is diagnosed on a lateral wrist radiograph by dorsal tilting of the lunate with an increased scapholunate angle (usually greater than 70°), most commonly due to scapholunate ligament injury.

If you want, send me a specific wrist X-ray and I’ll walk you through it step-by-step exactly as in a viva or OSCE scenario.