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Patient characteristics differently affect early cup and stem loosening in THA: a case-control study on 7,535
1MEM Research Center in Orthopaedic Surgery, Institute for Evaluative Research in Orthopaedic Surgery, University of Bern, Bern, Switzerland. christoph.roeder@memcenter.unibe.ch
Insights
Patient characteristics impact total hip arthroplasty (THA) component loosening differently. While age and weight reduced cup loosening, women had lower stem loosening odds, and higher BMI increased stem loosening risk.
Area of Science:
- Orthopedic surgery
- Biostatistics
- Medical device research
Background:
- Early loosening of total hip arthroplasty (THA) components is a significant concern.
- Understanding patient-specific risk factors is crucial for improving implant survival rates.
Purpose of the Study:
- To investigate how various patient characteristics influence the early loosening of THA cups and stems.
- To identify differential effects of patient factors on the loosening of acetabular and femoral components.
Main Methods:
- Two matched case-control studies were conducted.
- Analysis included 3,028 acetabular cups and 5,224 femoral stems.
- Loosening was defined by radiographic signs of mechanical failure or revision for aseptic loosening.
Main Results:
- Women had lower odds of stem loosening compared to men.
- Increasing age and weight were associated with decreased odds of cup loosening.
- Higher Body Mass Index (BMI) correlated with increased odds of stem loosening.
- Charnley classes B and C demonstrated a protective effect against loosening for both components.
- No significant risk differences were observed across main diagnoses.
Conclusions:
- Patient characteristics exhibit differential effects on early THA cup and stem loosening.
- Age, weight, and sex are significant factors influencing component survival.
- BMI and Charnley classification play a role in THA component stability.
Abstract:
We postulated that certain patient characteristics have different effects on early THA component loosening. With two matched case-control studies we assessed 3,028 cups and 5,224 stems. Loosening was defined using signs of mechanical component failure on routine follow-up radiographs or revision for aseptic loosening. Women and men had similar cup-loosening odds, but women had lower odds for stem loosening (p < 0.0001). Odds for cup loosening decreased by 2.1% per additional year of age (p = 0.0004), those for stem loosening by 2.4% (p < 0.0001). Each additional kilogram of weight decreased cup loosening odds by 1.3% (p = 0.0051). Each additional unit of BMI increased stem loosening odds (p = 0.0109). Charnley classes B and C were protective factors against loosening of both components. There were no risk differences for the various main diagnoses. Certain patient characteristics differently affected early cup and stem loosening, although some characteristics had the same protective or harmful effect on component survival.
