1. The Joint Exam in Ehlers-Danlos Syndrome
Dr. Elizabeth Russell M.D.
Div. Rheumatology
Medical College of Wisconsin

3. A continuum: Normal range of motion Laxity Subluxation (voluntary) Subluxation (involuntary) Dislocation

4. Many populations have considerably greater joint laxity as “normal”
Laxity is relative!
Many populations have considerably greater joint laxity as “normal”
(ex. Egypt, India)

5. Laxity
Laxity is voluntary or involuntary joint range of motion exceeding accepted normal range.
Instability is laxity that results in greater joint dysfunction (example: subluxation) and is involuntary.

6. Laxity
What causes it?

7. Normal constraints to range of motion of any joint are multifactorial:
Bone contours
Capsule
Intraarticular meniscus
Ligaments
Muscles
Adjacent soft tissues
Gravity

9. Abnormal bone end contours
Can be secondary to injury
Can be secondary to congenital malformation

11. Capsule abnormality Can be torn (trauma)
Can have altered physical properties (example Hypermobile EDS where tissue structure allows greater stretching in a tissue without inherent recoil)

12. Intraarticular meniscus
Normally found in knee, temporomandibular joints
Helps control excursion of bone ends, distribute forces
Can be torn or undergo degeneration

13. Muscle abnormality
Bulk of overlying muscle affects joint motion allowed by spatial interference
Tone of adjacent muscles helps hold bone ends together: more tone = less likelihood bone end excursion (example: subluxations in EDS during sleep when muscle tone decreased)

14. Adjacent soft tissue abnormality
Compliance of adjacent tissues affects range of motion (example: increased overlying collagen deposition in scleroderma decreases joint range of motion; converse in forms of EDS where skin thin, decreased fat in subdermis)

15. Effect of gravity!
Gravitational force exerted on weight-bearing joints helps hold joints together assuming alignment is normal (example: this may be an issue in EDS when involuntary subluxations occur in bed at night in lower extremity joints)

16. Assessment of Laxity/Instability: Best Assessed by Physical Exam
Radiology largely a static assessment;
Newer technologies will be dynamic

17. Assessment by Other Modalities:
Ultrasound may be used for large joint instability assessment; less useful for small joints
X-ray useful to assess end-point excursion of bone ends
MRI just starting to be utilized as dynamic study

18. The Physical Exam Inspection: alignment important
Palpation: can differentiate osseous vs. soft tissue prominence
Range of motion: key to assessing laxity
Instability testing

19. Laxity testing:
Can be done within only 1 plane or assessed in multiple planes, keeping normal physiologic range of motion in mind (example: the shoulder needs to tested in multiple planes given the usual large ROM)

20. Special Techniques:
“Click Sign” for capsular laxity: examiner distracts bones and reopposes in effort to assess capsule tightness. Look for dimpling of overlying skin during distraction and a “click” felt when articular surfaces abut again

21. Evaluation of joint laxity in a patient with hypermobile EDS
Video
Evaluation of joint laxity in a patient with hypermobile EDS

23. What to do with exam data
Beighton scores: estimation of joint laxity at 5 sites (thumb, finger,elbow,knee,spine)
Hypermobility defined as values greater than 6
Useful as a standard for comparison

24. Presence of small joint hypermobility only
More associated with vascular form of Ehlers-Danlos Syndrome

25. Presence of generalized hypermobility
Seen in most forms of Ehlers-Danlos Syndrome (not dermatosparaxis) but most noticeably in arthrochalasia and hypermobile forms

26. Presence of large joint hypermobility only
Most characteristic of hypermobile form of Ehlers-Danlos Syndrome

27. Beighton scoring provides some quantification of laxity
In summary:
Approaching assessment of hypermobility should take into consideration various factors that influence laxity
Physical exam should look for excess range of motion as well as for evidence of subluxation
Beighton scoring provides some quantification of laxity