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. 2025 Jan 3;12(1):e70143.
doi: 10.1002/jeo2.70143. eCollection 2025 Jan.

Varus alignment of the hip and knee 2 years after anterior cruciate ligament injury is associated with medial tibiofemoral osteoarthritis 3 years later

Henrik Nilsson  1 , Martin Englund  2 , Richard Frobell  3 , L Stefan Lohmander  3 , André Struglics  3 , Per Swärd  1   3
Affiliations

Varus alignment of the hip and knee 2 years after anterior cruciate ligament injury is associated with medial tibiofemoral osteoarthritis 3 years later

Henrik Nilsson et al. J Exp Orthop. .

Abstract

Purpose: To investigate if hip and knee alignment assessed 2 years after anterior cruciate ligament (ACL) injury is associated with compartment-specific radiographic knee osteoarthritis (OA) 3 years later.

Methods: An exploratory analysis was conducted in the knee ACL, nonsurgical versus surgical treatment (KANON) trial (ISRCTN84752559); 115 subjects with acute ACL injury were assessed at the 2-year follow-up; full-limb images of the injured leg were acquired, and the neck-shaft angle (NSA) and hip-knee-ankle angle (HKA) were measured. At the 5-year follow-up, weight-bearing tibiofemoral and patellofemoral radiographs were obtained. Radiographs were graded according to the OA Research Society International Atlas and Radiographic OA was defined as approximating Kellgren & Lawrence grade 2 or worse. Analysis of covariance adjusting for sex, age, body mass index, randomization and partial meniscectomy recorded at the 2-year follow-up was performed.

Results: In patients who had developed medial tibiofemoral OA at the 5-year follow-up, the NSA and the HKA at the 2-year follow-up were smaller (NSA, mean difference = -4.6° [95% confidence interval {CI} -7.9° to -1.1°]; HKA, mean difference = -2.3° [95% CI -4.2° to -0.4°]). No association was observed between the NSA or HKA at the 2-year follow-up and lateral tibiofemoral OA, nor patellofemoral OA at the 5-year follow-up.

Conclusion: A smaller NSA and HKA angle of the ACL injured leg (i.e., more varus hip and varus knee alignment) 2 years after the injury was associated with medial tibiofemoral radiographic OA 3 years later.

Level of evidence: Level II exploratory post hoc analysis of an RCT.

Keywords: alignment; anterior cruciate ligament; hip knee ankle angle; neck‐shaft angle; osteoarthritis.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
A schematic illustration of the HKA and the NSA measurements. Full‐limb radiographs were obtained of the injured leg with the radiographed leg in weight‐bearing and in slight knee flexion. The HKA was assessed by drawing a line from the centre of the femoral head to the centre of the tibial spines. An additional line was drawn from the centre of the trochlea of talus to the centre of the tibial spines. The HKA angle was defined as the medial angle at the intersection of the two lines. The NSA was defined as the angle between the femoral neck axis and the femoral long axis. The femoral neck axis was defined as the line between the centre of the femoral head and the femoral neck centre. The two radiographs are from one of the patients in the knee anterior cruciate ligament, nonsurgical versus surgical treatment study. HKA, hip‐knee‐ankle angle; NSA, neck‐shaft angle.
See this image and copyright information in PMC

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