Patellar Tracking and Anterior Knee Pain are Similar After Medial Parapatellar and Midvastus Approaches in Minimally Invasive TKA

Background Since the medial parapatellar (MPP) approach in conventional TKA can cause patellar maltracking and anterior knee pain, some orthopaedic surgeons use the midvastus (MV) approach instead of the MPP approach to reduce patellar maltracking. Minimally invasive surgical (MIS) TKA has been developed to limit the damage to the surrounding muscle and reduce the necessity of patellar eversion during surgery. Thus, MIS TKA might be associated with proper patellar tracking and a low incidence of anterior knee pain. However, this presumption has not been confirmed.

Questions/purposes We asked whether the incidence of patellar maltracking and anterior knee pain differed with the MV and MPP in association with MIS TKA.

Methods We prospectively followed 59 patients (60 knees) treated with 60 primary cemented MIS TKAs from August 2009 to September 2010. We randomized the patients into two groups: 30 who had a limited MPP approach and 30 who had a mini-MV approach. We recorded the occurrence of anterior knee pain, patellar tilting, and subluxation. The minimum followup was 12 months (mean, 18.03 months; range, 12.00-25.08 months).

Results We found no differences in anterior knee pain (two of 30, 7% versus two of 30, 7%), mean patellar tilt (3.4° ± 2.9° versus 3.0 ± 2.3°), and mean patellar subluxation (1.5 ± 1.1 mm versus 1.1 ± 0.7 mm) between the limited MPP and mini-MV groups, respectively.

Conclusions MIS TKA using either the MPP or MV approach has a low incidence of patellar maltracking and anterior knee pain.

Level of Evidence Level I, therapeutic study. See the Guidelines for Authors for a complete description of the levels of evidence.