Leg length inequality in total hip arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Medical Device Design

Background:

• Postoperative leg length inequality is a common complication after total hip arthroplasty (THA).
• This disparity often leads to medical liability concerns due to the absence of established standards for acceptable leg length difference.
• Modular stems offer potential advantages in controlling femoral offset and sizing for limb length restoration.

Purpose of the Study:

• To compare the effectiveness of two different femoral stem protocols in restoring leg length after THA.
• To evaluate the incidence of leg length discrepancy associated with tapered versus modular stem designs.

Main Methods:

• A retrospective analysis comparing two patient cohorts undergoing THA.
• The 2001 cohort exclusively used tapered stems, prioritizing canal fit.
• The 2004 cohort utilized porous-tapered or S-ROM modular stems based on preoperative templating to restore femoral head rotation center.

Main Results:

• The 2001 cohort experienced a mean leg length increase of 7 mm.
• In the 2004 cohort, 25% of cases were unsuitable for tapered stems.
• S-ROM stems in the 2004 cohort resulted in a mean leg length increase of 4 mm, consistently avoiding overlengthening.

Conclusions:

• The S-ROM modular stem demonstrated superior accuracy in restoring leg length compared to tapered stems.
• Modular stem designs, particularly the S-ROM, appear to mitigate the risk of leg length overlengthening in THA.
• Standardizing stem selection based on preoperative planning is crucial for minimizing postoperative leg length inequality.