Remodelling and pain after uncemented total hip replacement

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Radiology

Background:

• Uncemented hip replacements utilize porous or textured stems for bone ingrowth.
• The Lord prosthesis features a long, macrotextured stem designed for biological fixation.
• Long-term outcomes and biomechanical interactions of such implants require continued investigation.

Purpose of the Study:

• To evaluate long-term radiographic changes and pain incidence after uncemented hip replacement using the Lord prosthesis.
• To investigate the relationship between thigh pain, bone remodeling, and implant-bone interface characteristics.
• To understand the biomechanical implications of stem design on femoral bone remodeling.

Main Methods:

• Radiographic analysis of 70 patients with Lord prosthesis hip replacements at 1, 5, and final follow-up (mean 9.5 years).
• Assessment of thigh pain and correlation with radiographic findings, including cortical bone loss and radiolucent lines.
• Statistical analysis to determine relationships between pain, activity levels, and bone remodeling parameters.

Main Results:

• 36% of patients reported thigh pain.
• Active patients with thigh pain showed less proximal cortical bone loss and more distal bone formation.
• Incomplete radiolucent lines at the mid-stem correlated with increased cortical width, suggesting elastic displacement.
• Cortical remodeling continued beyond 5 years, except at the prosthesis tip.

Conclusions:

• Relative elastic displacement at the prosthesis-bone interface may cause thigh pain after uncemented hip replacement.
• This displacement appears to influence the pattern of femoral bone remodeling.
• The Lord prosthesis design may lead to specific biomechanical interactions affecting long-term bone adaptation.