Cross-sectional prevalence study of 250 asymptomatic young adults (500 knees) using full-leg standing radiographs. Asked: what fraction of the normal population has natural varus alignment of ≥3° at skeletal maturity, and which anatomic factors drive it? Introduced the term 'constitutional varus' for this normal variant.
The dogma entering this paper was clear: restore neutral mechanical alignment in every TKA, because 0° HKA means equal load distribution and better implant survival. Bellemans showed that premise is built on a false assumption — nearly a quarter of adults never had neutral alignment to begin with.
When you pull up a TKA patient's full-leg films and see varus, check the MPTA and mLDFA before assuming the deformity is degenerative. If the tibia is natively varus (low MPTA) and the femur contributes varus bowing (high mLDFA), this patient may have been living in varus since age 20. Forcing neutral in that setting means a medial release on a knee that was never tight. And producing kinematics the patient has never experienced.
This paper is the epidemiologic foundation for the kinematic and restricted-kinematic alignment philosophies that followed. Parratte et al. (2010) found no survival difference at 15 years for TKAs outside the neutral ±3° zone. Cited here as early evidence that a patient-specific alignment target may be appropriate for some individuals.
Cross-sectional prevalence study of 250 asymptomatic young adults (500 knees) using full-leg standing radiographs. Asked: what fraction of the normal population has natural varus alignment of ≥3° at skeletal maturity, and which anatomic factors drive it? Introduced the term 'constitutional varus' for this normal variant.
The dogma entering this paper was clear: restore neutral mechanical alignment in every TKA, because 0° HKA means equal load distribution and better implant survival. Bellemans showed that premise is built on a false assumption — nearly a quarter of adults never had neutral alignment to begin with.
When you pull up a TKA patient's full-leg films and see varus, check the MPTA and mLDFA before assuming the deformity is degenerative. If the tibia is natively varus (low MPTA) and the femur contributes varus bowing (high mLDFA), this patient may have been living in varus since age 20. Forcing neutral in that setting means a medial release on a knee that was never tight. And producing kinematics the patient has never experienced.
This paper is the epidemiologic foundation for the kinematic and restricted-kinematic alignment philosophies that followed. Parratte et al. (2010) found no survival difference at 15 years for TKAs outside the neutral ±3° zone. Cited here as early evidence that a patient-specific alignment target may be appropriate for some individuals.