Patterns of Shapiro for Developmental Lower Limb Length Discrepancy

 

Since we are dealing with a developmental cause, the assumption is that there is no lower limb discrepancy at birth or prior to the precipitating event. This means that graphical representation of the difference over time will start with discrepancy on y axis = 0 and will increase during the initial period.

 

When we look at the graphs shown by Shapiro on page 640, they can be divided into 3 zones - early, middle and late periods. The graphs in each period can indicate increasing, unchanging or decreasing discrepancies. Although there are perhaps 27 theoretical patterns for the graphical patterns, by the time constraints are applied there are only a few patterns seen in clinical practice. With the initial course increasing, there should be 9 patterns of increasing/plateau/decreasing for the middle and late course.

Initial Course	Middle Course	Late Course	Pattern
increasing	increasing	increasing	Type 1
increasing	increasing	slower increase (but not flat)	Type 2
increasing	decreasing	plateau	Type 3A
increasing	plateau	plateau	Type 3B
increasing	plateau	increasing	Type 4
increasing	plateau or decreasing	decreasing	Type 5

 

where:

• Type 3A is hard for me to visualize. It is described as showing a decreasing discrepancy with time (downward slope) then stabilizes and remains unchanged. Since we have the limbs start equal before a discrepancy is noted, there has to be an initial increasing discrepancy.

• The possible patterns not described are increasing-increasing-decreasing and increasing-decreasing-increasing.

 

Some examples of conditions resulting in a developmental lower limb length discrepancy:

(1) poliomyelitis

(2) femoral fracture

(3) juvenile rheumatoid arthritis

(4) septic arthritis

(5) Legg-Perthes disease

(6) neurofibromatosis

(7) hemangioma

(8) cerebral palsy