Ranawat and Shine describe the design principles, operative technique, and early outcomes of the duo-condylar total knee arthroplasty developed at the Hospital for Special Surgery. This cruciate-retaining, ligament-dependent condylar prosthesis built directly on Gunston's polycentric knee concept. The paper defines the indications, contraindications, and alignment targets that became the template for all subsequent condylar TKA design.
When you choose a cruciate-retaining TKA — which is most of what you will implant. You are operating within a framework Ranawat defined in 1973. The core premise has not changed: this design reconstitutes lost bone and cartilage but provides zero anteroposterior stability, so the posterior cruciate and collateral ligaments must be functional before you operate.
In clinic, apply the contraindications explicitly: AP subluxation, recurvatum >10°, and flexion contracture >25° each push the patient toward a constrained or hinge design. Varus deformity under 15° in an osteoarthritic knee still belongs in the osteotomy conversation. TKA is not automatically the answer.
The alignment targets Ranawat set. Femoral component at 75°–85° to the femoral axis, tibia within 10° of neutral, overall 0°–8° valgus. Are the same numbers in your instrumentation guides today. This paper also established why condylar TKA is preferable to hinge designs when infection risk is a concern: minimal bone resection keeps the medullary canal out of the zone of contamination and preserves arthrodesis as salvage.
Ranawat and Shine describe the design principles, operative technique, and early outcomes of the duo-condylar total knee arthroplasty developed at the Hospital for Special Surgery. This cruciate-retaining, ligament-dependent condylar prosthesis built directly on Gunston's polycentric knee concept. The paper defines the indications, contraindications, and alignment targets that became the template for all subsequent condylar TKA design.
When you choose a cruciate-retaining TKA — which is most of what you will implant. You are operating within a framework Ranawat defined in 1973. The core premise has not changed: this design reconstitutes lost bone and cartilage but provides zero anteroposterior stability, so the posterior cruciate and collateral ligaments must be functional before you operate.
In clinic, apply the contraindications explicitly: AP subluxation, recurvatum >10°, and flexion contracture >25° each push the patient toward a constrained or hinge design. Varus deformity under 15° in an osteoarthritic knee still belongs in the osteotomy conversation. TKA is not automatically the answer.
The alignment targets Ranawat set. Femoral component at 75°–85° to the femoral axis, tibia within 10° of neutral, overall 0°–8° valgus. Are the same numbers in your instrumentation guides today. This paper also established why condylar TKA is preferable to hinge designs when infection risk is a concern: minimal bone resection keeps the medullary canal out of the zone of contamination and preserves arthrodesis as salvage.