Ortho By Dave

Ortho By Dave

Two Frequently asked Orthopedic Questions:

  1. What is the Lachman Test of the knee used for and how is it performed?
    1. It is a non-invasive physical examination technique to assess Anterior Cruciate Ligament (ACL) integrity
    2. More reliable and sensitive than the anterior drawer test
    3. Patient is supine with knee flexed ~ 15° to 30° and slightly externally rotated
    4. One hand on anterior distal thigh, and the other hand on proximal posterior calf
    5. Apply force (posterior to anterior) to tibia while stabilizing the femur
    6. Estimate distance moved in mm and compare to unaffected side
    7. Record quality of end-point as hard (abruptly stops) or soft (elastic or no stop)
    8. Record difference compared to unaffected side in mm (>3 mm indicates ACL tear)

Mild – 0-5 mm

Moderate – 6-10 mm

Severe – 11-15 mm


Lachman Test Video

2.  What are the Types and Features of Osteogenesis Imperfecta (OI)?

OI is a genetic bone disorder characterized by fragile bones that easily break. It is also known as “brittle bone disease”. There are 8 identified types. Type II is the most severe and usually fatal in the neonatal period. Type I is mild. Types I, II, III, and IV involve defects/deficits in type 1 collagen.

Types (from OI foundation website www.oif.org )

1)     Type I – Mildest and most common form (50% of all OI patients)

   a)     Dominant inheritance (can be from spontaneous mutation)

   b)     Mild bone fragility

   c)      Relatively few fractures

   d)     Minimal limb deformity

   e)     Blue sclerae often present

   f)      High incidence of hearing loss

   g)     Lower than normal amount of Type I collagen – structure normal

   h)     Treatment: supportive

2)     Type II – Most severe form; usually die within weeks of delivery.

   a)     Results from a new dominant mutation in type 1 collagen gene

   b)     At birth – very short limbs, small chests, soft skulls, and low birth weights

   c)      Intrauterine fractures will be evident

   d)     Lungs are underdeveloped

   e)     Dark blue or gray sclerae

   f)      Genetic counseling for parents before any future pregnancies

   g)     Treatment – “off-label” bisphosphonates may be helpful

3)     Type III – Most severe type among children who survive neonatal period

   a)     Majority from dominant mutations in type 1 collagen gene

   b)     Degree of bone fragility and fracture rates vary widely

   c)      At birth – mildly shortened and bowed limbs, small chest, soft calvarium

   d)     Respiratory and swallowing problems are common

   e)     Progressive malformation with age

   f)      Markedly short stature (adults less than 3 feet 6 inches)

   g)     Sclerae may be white, blue, purple, or gray

   h)     Majority result from dominant mutations in type 1 collagen

   i)       Treatment: supportive- “Off-label” bisphosphonates may be helpful

4)     Type IV – Moderately affected. Ranging in severity from Type I to Type III

   a)     Autosomal dominant pattern of inheritance. (Many from a new mutation)

   b)     Structurally defective type 1 collagen

   c)      Often diagnosis is made later than birth

   d)     Fractures may not occur until walking

   e)     Bowing of long bones common

   f)       Moderate to severe growth retardation

   g)     Sclerae light blue in infancy but intensity variable. Lighten to white with age

   h)     Treatment: supportive

5)     Type V – Moderate severity similar to Type IV fractures and deformity

   a)     Large, hypertrophic calluses in largest bones after fracture or surgery

   b)     Hypertrophic callouses can arise spontaneously

   c)      Calcification of interosseous membrane between radius and ulna

   d)     Dominantly inherited

   e)     Represents 5% of moderate-severe OI cases

6)     Type VI – Extremely rare. Moderate in severity. Similar clinically to Type IV

   a)     Characteristic mineralization defect in biopsied bone

   b)     Probably recessive inheritance, but not yet confirmed

7)     Type VII – Recessive inheritance of mutation in CRTAP gene

   a)     Short leg bones, humerus, and femur common

   b)     Short stature common

   c)      Coxa vara common – Coxa Vara describes a deformity of the hip where the angle formed between the head and neck of the femur and its shaft (Mikulicz angle) is decreased

   d)     Sclerae white

8)     Type VIII – Recessive inheritance of mutation in the LEPRE1 gene

   a)     Severe growth deficiency

   b)     Extreme under-mineralization of the skeleton

   c)      Caused by absence or severe deficiency of prolyl 3-hydroxylase activity

   d)     Sclerae white


This Blog entry was written by Dave Majiros:

Dave Majiros, PA-C, MS, USAF-Ret. was born in Nanticoke, Pennsylvania and graduated with a BS as a Physician Associate from the US Air Force Physician Assistant Program at the University of Oklahoma in 1982. He received a Master of Science in Sports Medicine from Chapman University in 1986. He has practiced as a PA-C in Colorado, New York, and Pennsylvania in Emergency Medicine, Family Practice, and Orthopaedic Surgery/Sports Medicine. He has been an Assistant Professor, Academic Coordinator, and Clinical Coordinator at Seton Hill University in Greensburg, Pennsylvania. In his off-time, he enjoys fishing and hiking.

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