High femoral offset has 3.7-fold increased probability for aseptic femoral component loosening: study

Lateralized stems in primary cementless total hip arthroplasty (THA) are associated with aseptic femoral loosening.

Lukas Jud et al conducted a study to analyze the impact of high femoral offset (hFO) combinations, formed by lateralized stems or large femoral head lengths, on aseptic femoral component loosening.

The study was conducted at Balgrist University Hospital, Department of Orthopedics, University of Zurich, Forchstrasse, Zürich, Switzerland. The article has been published in ‘International Orthopaedics.’

Retrospective cohort study was performed including all patients that underwent primary cementless THA. Only adult patients (i.e., ≥ 18 years) and patients referred to a postoperative standard protocol were included. Patients were screened for aseptic femoral component loosening and grouped in aseptic loosening (AL) and non-aseptic loosening (nAL) group. Medical records were screened; implant details were noted and classified in hFO and standard femoral offset (sFO) combinations. Supposed risk factors for aseptic loosening were analyzed.

Key findings of the study were:

• Two thousand four hundred fifty-nine THA could be included, containing 14 THA (0.6%) with aseptic femoral component loosening.

• The AL group contained 11 hFO combinations (78.6%), whereas in the nAL group, 1315 hFO combinations (53.8%) were used.

• Subgroup analysis showed significant difference between two groups for hFO combinations (p = 0.014), age (p = 0.002), NSAR (p = 0.001), and bilateral THA on same day (p = 0.001).

• The multiple logistic regression analysis showed that hFO combination was the only variable for increased probability of aseptic loosening (OR, 3.7; p = 0.04).

The authors concluded – “High femoral offset combinations, formed by lateralized stems or large femoral head lengths in our collective of standard straight stems implanted by an anterior approach, show a 3.7-fold increased probability for aseptic femoral component loosening. Adjustment of the postoperative protocol may be considered in these cases to ensure proper stem ingrowth.”

Further reading:

High femoral offset as a risk factor for aseptic femoral component loosening in cementless primary total hip arthroplasty Lukas Jud et al International Orthopaedics (2024) 48:1217–1224 https://doi.org/10.1007/s00264-024-06116-5