Highly variable coronal tibial and femoral alignment in osteoarthritic knees: a systematic review

PurposeThere is a lack of knowledge about coronal alignment variability in osteoarthritic knees. Therefore, the purpose of this article was to systematically review the literature and collect data about the lower limb alignment including hip-knee-ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA) and the joint line convergence angle (JLCA) in osteoarthritic knees.MethodsA systematic review was performed using the electronic databases MEDLINE (PubMed), EMBASE and Google Scholar. The following keywords were used: (morphology OR geometr* OR anatomy OR alignment OR phenotypes), (coronal OR neutral OR varus OR valgus), (knee OR lower limb OR femur OR tibia) and (osteoarthritis OR arthritis). Out of 110 full-text articles retrieved, 15 studies were included. Demographic information included author's names, year of publication, imaging modality, sample size and patient demographics (i.e. sex, age, etc.). Descriptive statistics, such as means, ranges, and measures of variance [e.g. standard deviations, 95% confidence intervals (CI)] for all angles (HKA, FMA, TMA, JLCA) are presented.ResultsThirteen studies reported mean overall HKA angles ranging from 163.5 degrees 2.3 degrees to 179.9 degrees 4.8 degrees. The mean HKA angles in females were between 164.1 degrees +/- 7.2 degrees and 178.8 degrees +/- 4.8 degrees, and in malesbetween 163.4 degrees +/- 5.5 degrees and 177.4 degrees +/- 3.9 degrees. The lowest and highest reported HKA angles were -27.7 degrees and +22.0 degrees, respectively. Seven studies reported mean FMA angles. Mean values ranged from 92.7 degrees +/- 2.7 degrees valgus to 88.6 degrees +/- 2 degrees varus. The reported mean FMAs for male were 87.9 degrees +/- 0.5 degrees to 90.7 degrees +/- 3 degrees and for female 89.91 degrees +/- 2.8 degrees to 92.9 degrees +/- 3.1 degrees. Six studies reported mean TMA values. TMA ranged from 81.7 degrees +/- 3.9 degrees varus to 87.7 degrees +/- 4.1 degrees varus. Only three studies reported mean JLCA angles, which ranged from -4.3 degrees to -6.4 degrees +/- 3.8 degrees.Conclusion Osteoarthritic knees showed a huge variation in overall coronal limb alignment as well as in femoral and tibial coronal alignment. Current total knee arthroplasty (TKA) alignment philosophies and preoperative planning do not sufficiently consider these variation, which might be one reason for unhappy knees after TKA.Level of evidence IV, systematic review.