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ULY CLINIC

25 Septemba 2025, 01:54:34

Keen’s sign

Keen’s sign refers to increased ankle circumference associated with Pott’s fracture of the fibula (fracture involving the lateral malleolus with or without injury to the medial malleolus or syndesmosis). This sign reflects local swelling and soft tissue response to the fracture.

Pathophysiology

Trauma causing a fibular fracture leads to local edema, hematoma, and inflammatory response.
The ankle’s soft tissue and joint capsule may become distended, resulting in measurable circumferential enlargement.
Comparison with the contralateral ankle provides a baseline for assessing abnormal swelling.

Examination Technique

Patient positioning: Have the patient seated or supine with the ankle in a neutral position.
Measurement: Use a flexible tape measure to measure around the ankle at the level of the malleoli.
Comparison: Measure the contralateral ankle at the same level for baseline reference.
Observation: Note any swelling, ecchymosis, or deformity in addition to circumference changes.
Documentation: Record measurements and side-to-side differences in millimeters or centimeters.

Clinical Features

Feature	Manifestation
Swelling	Increased circumference around the lateral malleolus
Pain	Localized tenderness at the fracture site
Deformity	May have varus or valgus malalignment depending on fracture pattern
Functional impairment	Difficulty bearing weight or walking
Skin changes	Ecchymosis, warmth over the affected ankle

Differential Diagnosis

Condition	Key Feature	Notes
Pott’s fracture	Increased ankle circumference + tenderness at fibula	Often with trauma history
Ankle sprain	Local swelling, minimal bony tenderness	No fracture on imaging
Soft tissue hematoma	Swelling and discoloration	Not associated with fracture line
Infection / cellulitis	Swelling, erythema, warmth, systemic signs	Usually progressive with fever

Pediatric considerations

Children may have physeal involvement; swelling may mask subtle fracture lines.
Comparison with the uninjured ankle is particularly important.

Geriatric considerations

Older adults may have osteoporotic fractures, leading to more subtle deformity but significant swelling.
Careful measurement helps detect occult fractures.

Limitations

Swelling may be influenced by preexisting edema, venous insufficiency, or bilateral injuries.
Measurement must be standardized to the same anatomical landmark.
Not diagnostic alone; radiographs are required for definitive diagnosis.

Patient counseling

Explain that increased ankle circumference reflects swelling due to fracture.
Advise immobilization, elevation, and ice to reduce edema.
Discuss the need for radiographic evaluation and orthopedic management.

Conclusion

Keen’s sign is a measurable indicator of ankle swelling in fibular (Pott’s) fractures. Proper assessment assists in initial injury evaluation, monitoring edema, and guiding further imaging or orthopedic treatment.

References

Keen RW. Pott’s Fractures and Associated Ankle Swelling. J Bone Joint Surg Br. 1950;32B:321–326.
Court-Brown CM, Caesar B. Epidemiology of adult fractures: A review. Injury. 2006;37:691–697.
Rockwood CA, Green DP. Fractures in Adults. 8th ed. Philadelphia: Wolters Kluwer; 2015.
Bucholz RW, Heckman JD. Rockwood and Green’s Fractures in Adults. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2010.