Mobile-bearing medial unicompartmental knee arthroplasty restores limb alignment comparable to that of the unaffected contralateral limb

• Published in: Acta orthopaedica Vol. 88; no. 1; pp. 70 - 74
• Main Authors: Mullaji, Arun B, Shah, Siddharth, Shetty, Gautam M
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 01-02-2017; Medical Journals Sweden
• Subjects: Aged; Arthroplasty, Replacement, Knee - methods; Female; Femur - diagnostic imaging; Femur - surgery; Follow-Up Studies; Humans; Knee; Knee Joint - diagnostic imaging; Knee Joint - surgery; Knee Prosthesis; Male; Middle Aged; Osteoarthritis, Knee - diagnosis; Osteoarthritis, Knee - physiopathology; Osteoarthritis, Knee - surgery; Postoperative Period; Retrospective Studies; Tibia - surgery; Weight-Bearing
• ISSN: 1745-3674; 1745-3682
• DOI: 10.1080/17453674.2016.1253327

Background and purpose - Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. We investigated whether restoration of natural soft tissue tension would result in a lower limb alignment similar to that of the contralateral unaffected lower limb after mobile-bearing medial UKA.
Patients and methods - In this retrospective study, hip-knee-ankle (HKA) angle, position of the weight-bearing axis (WBA), and knee joint line obliquity (KJLO) after mobile-bearing medial UKA was compared with that of the unaffected (clinically and radiologically) contralateral lower limb in 123 patients.
Results - Postoperatively, HKA angle was restored to within ±3° of the contralateral lower limb in 87% of the patients and the WBA passed within ±1 Kennedy and White's tibial zone of the unaffected contralateral lower limb in 95% of the patients. The mean KJLO in the operated limbs was not significantly different from that in the unaffected lower limbs (p = 0.07) and the KJLO in the operated limb was restored to within ±3° of that in the contralateral lower limb in 96% of the patients.
Interpretation - Lower limb alignment and knee joint line obliquity after mobile-bearing medial UKA were comparable to that of the unaffected contralateral limb in most patients. Comparison with the contralateral unaffected lower limb is a reliable method for evaluation and validation of limb mechanical alignment after mobile-bearing medial UKA.