High 10-year survival rate with an anatomic cementless stem (SPS)

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Materials Science

Background:

• Anatomic cementless stems aim for better femoral fit and reduced stress-shielding in hip arthroplasty.
• Early designs were associated with thigh pain, prompting the development of new stems based on average femoral geometry.
• The efficacy of a novel anatomic cementless stem in reducing thigh pain remains to be determined.

Purpose of the Study:

• To evaluate if a new anatomic cementless stem design is associated with a low incidence of thigh pain.
• To assess the durability of fixation provided by the new stem design.
• To determine the functional outcomes and long-term survivorship of the implant.

Main Methods:

• A review of 171 patients (176 total hip arthroplasties) who received the anatomic proximal hydroxyapatite-coated stem.
• Assessment of pain and function using the Harris hip score (HHS) at a mean 10-year follow-up.
• Evaluation of femoral stem fixation and stability using established scoring systems and 10-year survival analysis.

Main Results:

• Only two patients (slight, non-limiting thigh pain) reported discomfort at final follow-up.
• All stems showed radiographic stability; one was nonintegrated but stable.
• 10-year survival for stem revision due to aseptic loosening was 100%.

Conclusions:

• The novel anatomic cementless stem design, featuring metaphyseal fixation, offers durable proximal stem stability and fixation.
• The design's characteristics (medial-lateral flare, sagittal curvature, torsion) contribute to its successful clinical performance.
• This implant represents a viable option for achieving stable and functional outcomes in total hip arthroplasty.