Effects Of Partial Meniscectomy For Lateral Discoid Meniscus On Patellar Tracking

Objective: To investigate the effects of arthroscopic partial meniscectomy for torndiscoid lateral meniscus on patellar tracking, and to evaluate the clinical outcomes of theoperation.Methods: Patients who were diagnosed as having torn discoid lateral meniscus(DLMs) using MRI, and those who decided to undergo arthroscopy for this disease in ourhospital between September2010and February2012were studied. Before the operation,the Lysholm scores of the patients were recorded. All the patients were examined withupright weight-bearing MRI pre-operation. According to the inclusion and exclusioncriteria, a total of112patients (112knees) were participated in the study. One monthpost-operation, all the subjects were examined with upright weight-bearing MRI andevaluated the clinical outcomes with the Lysholm scores and Ikeuchi grade. Axial-planeimages through the maximum width of the patella and the maximum dorsal area of thefemoral condyles were superimposed. The bisect offset index was used to quantify patellartranslation. Statistical analysis was performed with SPSS software for Windows version17.0. The differences in the bisect offset index and Lysholm scores between pre-andpost-operation were compared by use of the paired t-test. P <0.05was considered to bestatistically significant.Results: Before the operation, the mean bisect offset index was0.574(0.437to0.692), and the mean Lysholm scores were54.4（17～82）. One month after the operation,the mean bisect offset index was0.622(0.510to0.801), and the mean Lysholm scoreswere65.1（40～95）. According to the scale of Ikeuchi,95of the112knees (84.8%)showed clinically excellent or good results at one month after the operation. One monthafter the operation, the bisect offset index increased by an average of0.048(-0.018to0.129) compared with the pre-operation value, which is a statistically significant result(P<0.01). One month after the operation, the Lysholm scores increased by an average of 10.6(-24～35) compared with the pre-operation value, which is a statistically significantresult (P<0.01).Conclusion: Arthroscopic partial meniscectomy is effective for the treatment of tornDLMs with less trauma and faster recover. In this study, the patellar bisect offset indexincreased after the operation, revealing that the patella translated more lateral to thefemoral trochlear groove after the arthroscopic partial meniscectomy for torn DLM. Lateralpatellar translation might be one of the factors contributing to patellofemoral pain afterarthroscopic partial meniscectomy for torn DLM. Tracking the position of the patella usingthe methods described in this study could be extremely useful for discerning theeffectiveness of rehabilitation training. Special functional training may be necessary tomaintain patellar stability, and this supplemental therapy might decrease the incidence ofpatellofemoral pain.