Anthony M. DiGioia III, MD: January 2008 Archives

Addressing your questions and concerns
"I had my left hip replaced a month ago and everything is going well except that I feel off-balance, like my left is now longer than my right."
 
"My Physical Therapist told me that the leg that was operated on is longer than the other.  What am I supposed to do about that?"
 
"Now that my right hip has been replaced, I use a lift in the heel of my left shoe to balance out my legs.  My doctor prescribed the lift for me to make me more comfortable."
 
A common concern that patients have after total hip replacement surgery is a feeling that their legs are different lengths.  This is called limb length discrepancy (LLD).  The following information will explain the different types of LLD, possible explanations for its occurrence, and treatment options for patients who are uncomfortable with a LLD.
 
The Different Types of LLD
Apparent LLD:  Some people have an "apparent" LLD which may make the affected leg seem longer than the other leg.  There are several factors that can contribute to this feeling.  Most commonly, contractures or shortening of the muscles surrounding the hip joint and pelvis make the involved leg feel longer even when they are really the same length.  Also, contractures of the muscles around the lower back from spinal disorders (i.e. arthritis, spinal stenosis), curvatures of the spine from scoliosis, and deformities of the knee or ankle joint can make one leg seem longer or shorter.  In the general public, some people have an "apparent LLD" as long as one half inch but usually don't notice it because the LLD occurs over time.
 
True LLD:  A "true" LLD is where one leg is actually longer than the other.  Patients can have unequal leg lengths of ¼ inch to ½ inch and never feel it too!
 
Combined LLD:
 You can also have combinations of "true" and "apparent" LLD's.
 
Adjusting Leg Lengths in Surgery
During total hip replacement surgery, the surgeon may "lengthen" the involved leg by stretching the muscles and ligaments that were contracted, as well as by restoring the joint space that had become narrowed from the arthritis.  This is usually a necessary part of the surgery because it also provides stability to the new hip joint.  Your surgeon takes measurements of your leg lengths on x-ray prior to surgery.  Your surgeon always aims for equal leg lengths if at all possible and measures the length of your legs before and during surgery in order to achieve this goal.  Occasionally, surgeons may need to lengthen the operable leg to help improve stability and prevent dislocations as well improve the muscle function around the hip.
 
Right after your surgery it may feel like the leg that has been operated on is longer.  One reason is that as opposed to the months to years that it took for your leg to shorten and muscles to become contracted, your surgeon has "lengthened" them in a very short period of time.  It may take time, but your muscles usually readjust to their new position.    Usually, it takes between 8 to 12 weeks for you to feel re-balanced. 
 
Important:  You must also understand that leg lengths and the potential for dislocations after surgery go hand in hand.  Ideally, surgeons always aim for equal leg lengths and a very stable hip.  However, at times, because of findings during your surgery, the surgeon may elect to make the operative leg a bit longer in order to tighten up the joint and prevent a possible dislocation.  Small differences in LLD are usually well tolerated by patients given time.  However, it is most important to understand that it's better from your perspective to have a slightly longer leg if necessary to prevent dislocations rather than a hip that is at risk for dislocating.
 
Treatment Options for Feeling "Off-Balance" after Hip Surgery
Most of the time, patients never feel this difference and therefore no treatment is needed.  As previously stated, it may take a few months for your muscles to readjust.  In the early months after surgery, interventions like stretching and strengthening exercises may actually speed the natural course of re-balancing.  Factors that will influence whether you continue to feel the difference include arthritis of the opposite hip, spinal muscle contractures, scoliosis, and deformities or stiffness of the ankle and knee joints.
 
When patients continue to notice symptoms of LLD, treatment usually consists of inserting a "lift" into the shoe of the shorter leg.  In some patients, one or two of the simple over the counter Dr. Scholl's-type heel inserts can be enough.  Occasionally, patients may need a thicker insert.  The goal of treatment and size of the insert is always based on how you feel and we recommend that you use the standing blocks as the best way to measure what makes you feel you feel balanced, rather than tape measures or x-rays.
 
We hope this information has been useful to you.  If you have questions about LLD after surgery, please don't hesitate to ask your surgeon or assistant.                                         
 

 (from The Journal of Bone & Joint Surgery, Volume 89-A, Number 12, December 2007)

·           The upward trends in the utilization of total hip and knee replacement between 1969 and 2003 detail the national need for these procedures.

·           The age and gender-adjusted incidence per 100,000 person-years significantly increased from 1971 to 2003, representing a greater than 400% increase in the incidence of total knee replacement (as compared with a 55% increase in total hip replacement during the same period).

·           There was a significantly higher utilization rate for women.

·           The incidence increased with the patient's age for total knee replacement, except in patients more than eighty years old.

·           The largest percentage increase was in patients less than fifty years old.

·           There was a significant increase in the proportion of total knee replacements performed for the treatment of osteoarthritis, from 51% during 1971-1975 to 92% in 2000- 2003.

·           This also reflects a reduction in the incidence of total knee replacements performed for the treatment of rheumatoid arthritis over the same period.

·           It is projected that the number of primary total knee replacements will increase from 450,400 to 3.48 million by 2030, compared with a growth in the number of primary total hip replacements from 208,600 to 572,100 during the same interval.

·           The volume of revision total hip replacements is projected to grow from 40,800 in 2005 to 96,700 in 2030 (a 137% increase).

·           The volume of revision total knee replacements is projected to grow from 38,300 in 2005 to 268, 200 in 2030 (a 600% increase).

·           The continued and rapid growth of utilization of total knee replacement reflects a trend that will require additional resources in the future.

·           This dramatically increased demand for replacement procedures will require additional discussions regarding the distribution of economic resources; the allocation of surgeons, facilities and resources; and improved operative efficiency.

·           Additionally, given the growth in the number of procedures in the younger, more active patients, implant longevity will require further enhancement.