Charnley's 1970 paper presents the design rationale and 5–7 year outcomes of low-friction arthroplasty. The technique pairs a 22 mm cobalt-chrome femoral head with a high-density polyethylene socket fixed with acrylic cement, combined with biomechanical reconstruction of hip lever arms to reduce joint loading. The central question is whether this construct delivers durable pain relief and low mechanical failure rates at medium-term follow-up.
Every principle you use when selecting a THA bearing surface traces back to this paper. Before Charnley, large metal-on-metal heads (McKee-Farrar) dominated, with no systematic attention to frictional torque or biomechanical lever reconstruction. Charnley reframed THA not as anatomic replacement but as biomechanical reconstruction — a conceptual shift that persists today.
When you see a patient with a dysplastic or arthritic hip where the trochanter has migrated proximally and the center of rotation is lateralized, this paper is why you think about deepening the acetabulum and advancing the trochanter distally and laterally. Not just inserting components where the anatomy sits.
The wear physics here also explain why head diameter still matters in bearing surface selection: volumetric wear scales with sliding distance, and sliding distance scales with head radius. Larger heads improve range of motion and stability, but the tradeoff in debris generation drove decades of implant design.
Charnley's 1970 paper presents the design rationale and 5–7 year outcomes of low-friction arthroplasty. The technique pairs a 22 mm cobalt-chrome femoral head with a high-density polyethylene socket fixed with acrylic cement, combined with biomechanical reconstruction of hip lever arms to reduce joint loading. The central question is whether this construct delivers durable pain relief and low mechanical failure rates at medium-term follow-up.
Every principle you use when selecting a THA bearing surface traces back to this paper. Before Charnley, large metal-on-metal heads (McKee-Farrar) dominated, with no systematic attention to frictional torque or biomechanical lever reconstruction. Charnley reframed THA not as anatomic replacement but as biomechanical reconstruction — a conceptual shift that persists today.
When you see a patient with a dysplastic or arthritic hip where the trochanter has migrated proximally and the center of rotation is lateralized, this paper is why you think about deepening the acetabulum and advancing the trochanter distally and laterally. Not just inserting components where the anatomy sits.
The wear physics here also explain why head diameter still matters in bearing surface selection: volumetric wear scales with sliding distance, and sliding distance scales with head radius. Larger heads improve range of motion and stability, but the tradeoff in debris generation drove decades of implant design.