The most common complications following hip arthroplasty are leg length discrepancy and hip dislocation. Leg length discrepancy is relatively common following hip arthroplasty, with an incidence as high as 20% to 50%.

Maintaining equal leg length intraoperatively is a challenge for orthopedic surgeons, whose goal is to ensure normal gait and hip function postoperatively. To achieve increased hip stability, the surgeon may use a larger prosthesis, which may result in increased leg length compared with the contralateral side. Leaving an extremity shortened may result in postoperative hip instability, which is far more problematic.1,2

Preoperative assessment should include careful screening for differences in leg length, including hip contracture, pelvic obliquity, and congenital issues. Preoperative radiographs of the hip are used by orthopedic surgeons to create a template of the hip and determine the appropriate implant size. Achieving hip stability generally takes priority during surgery, and a small length discrepancy is considered acceptable in most cases.

Few patients with increased leg length will notice or have symptoms. However, large length discrepancies may cause postoperative nerve injury to the leg, gait disorders, and lower back and hip pain. A large difference in leg length is a significant source of dissatisfaction after hip arthroplasty and is one of the most common reasons for lawsuits against orthopedic surgeons.

Most people will tolerate a leg length discrepancy of up to 10 mm or approximately 3/8 inch. A difference of ≥1 cm, or approximately 7/16 inch, is noticeable in up to 50% of patients, and of those, 15% to 20% require shoe correction to resolve symptoms caused by the discrepancy.

Small leg length discrepancies can be treated with heel lift shoe inserts, but a lift >3/8 inch generally does not fit well in a shoe. A discrepancy of ≥7/16 inch generally requires a lift at the shoe bottom, and a discrepancy >2 cm generally requires surgical correction. Muscle tightness, pelvic tilt, and altered gait may cause leg length discrepancies after hip arthroplasty but these issues usually self-correct within 6 months of surgery and therefore shoe lifts generally are not prescribed until after this time period.1,2

Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).

References

  1. Maloney WJ, Keeney JA. Leg length discrepancy after total hip arthroplasty. J Arthroplasty. 2004;19:108-110.
  2. Desai AS, Dramis A, Board TN. Leg length discrepancy after total hip arthroplasty: a review of literature. Curr Rev Musculoskelet Med. 2013;6:336-341.
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