The Effect of Partial Lateral Facetectomy of the Patella on the Radiographic and Clinical Outcome of Unresurfaced Patellar-retaining Total Knee Arthroplasty

Background: Management of patellar maltracking during primary TKA is of considerable importance. Lateral release, which is generally performed for this purpose, is associated with several complications. Objectives: In this study, we aimed to evaluate the role of partial lateral facetectomy in tracking the patella in Total Knee Arthroplasty (TKA). Methods: In a retrospective study, the efficiency of partial lateral facetectomy of the patella in achieving proper tracking of the patella was evaluated in 116 patients who underwent unresurfaced patellar-retaining TKA. The radiographic outcome measures included the patellar tilt and patellar shift. The functional outcome was assessed with Kujala anterior knee pain scale. Results: The Mean±SD age of the patients was 66.3±7.6 years. The mean follow-up of patients was ‎‎20.6±8.9 months. The Mean±SD patellar tilt was ‎‎10.5±7.2‎‎‏°‎‏ before the surgery and ‏‎4.4±5‎‎‏° after ‏the operation ‏‎ (‎P‎<‎‏0.001‏‎). ‎The Mean±SD preoperative patellar shift was ‏‎3.3±4.3‎‏ mm which improved to ‏‎-‎‎0.2±2.8°‎‏ after the surgery ‏‎(‎P‎<‎‏0.001‏‎). ‎The Mean±SD Kujala score of the patients was ‏‎74.6±7.1‎, ‎‏ ‏ranging ‎from 54 ‏to ‎‏89. ‎No complication was recorded during the follow‎-‎up period. Conclusion: Partial lateral facetectomy of the patella provides an acceptable radiographic and ‎functional outcome in patients undergoing primary TKA. Therefore, it could be regarded as a ‎valuable alternative to lateral release in unresurfaced patellar-retaining TKA.‎

Kinematics and Mechanical Properties of Knees following Patellar Replacing and Patellar Retaining Total Knee Arthroplasty

Knee injury is a common medical issue. A full understanding of the kinematics and mechanical properties of knees following total knee arthroplasty (TKA) repair utilizing patellar replacement (only the base of the patella is replaced) versus patellar retaining surgical techniques is still lacking. In the current paper, we investigated magnetic resonance (MR) imaging data from knees repaired by these two methods and evaluated total knee models created using imaging reconstruction technology that simulated gait conditions. Results revealed that patellar replacement had little influence on tibiofemoral kinematics, although the tibia-surface equivalent stress increased slightly. By contrast, patellar replacement had a significant influence on the patellofemoral joint; patellar internal rotation, external rotation, and medial-lateral translation were all increased. Moreover, the stress distribution on patellar prostheses was altered, resulting in an increased surface maximal equivalent stress on the corresponding area. Moreover, during the gait cycle, we found that the area with maximal equivalent stress shifted its position. Finally, the patellofemoral joint showed decreased motion stability. From the view of kinematics and mechanics, this paper suggests that patella should be retained during TKA if it is possible. The present study presented approaches and technologies for evaluating kinematics and mechanical properties of total knee joint after TKA under gait loads.