Modified Medial Collateral Ligament Indentation Technique in Total Knee Arthroplasty with Severe Type II Valgus Deformity

Objective: To explore the feasibility and clinical efficacy of a modified medial collateral ligament indentation technique in total knee arthroplasty (TKA) with severe type II valgus deformity. 
Methods: Consecutive patients with Krackow type II valgus deformity >20° who underwent a primary unilateral TKA between May 2008 and June 2017 were studied retrospectively. A medial collateral ligament indentation technique was performed in 20 patients (MCLI group), and 23 patients received the routine lateral structures release technique (LSR group). Radiological parameters, such as the valgus angle (VA), and functional outcomes including the use of constraint implants, Knee Society Score (KSS), Knee Society Function score (KSF), and thickness of the polyethylene insert were compared between the two groups. 
Results: A total of 43 consecutive patients had a minimum 2-year follow-up. The preoperative VA was comparable between the MCLI (23.5° ± 5.8°) and LSR groups (21.3° ± 3.2°, P = 0.134), as was the postoperative VA (1.1° ± 2.1° and 2.5° ± 3.0°, respectively, P = 0.084). The mean KSS and KSF scores in the MCLI group were 30.2 ± 4.8 and 38.8 ± 4.8, respectively, before surgery, and they increased to 91.3 ± 2.6 and 86.5 ± 2.4 at the last follow-up. The scores in the LSR group were 31.5 ± 7.5 and 36.5 ± 7.8 before surgery and 92.4 ± 3.5 and 88.5 ± 3.6 at the last follow-up. While no statistically significant differences in pre- or postoperative functional scores were found between the two groups, the MCLI group had thinner polyethylene inserts (9.5 ± 1.1 mm vs 12.9 ± 1.5 mm) and less use of constrained condylar inserts (15% vs 69.6%). During follow-up, the MCLI group had fewer complications. 
Conclusion: A modified MCLI technique can achieve good outcomes in TKA with type II valgus deformity of >20°. It can maintain a normal joint line level, reduce the use of constrained condylar knee prostheses, and is a reliable choice for severe genu valgum.