Cartilage MRI relaxation times after arthroscopic partial medial meniscectomy reveal localized degeneration

Purpose Little is known about the early changes in cartilage composition and tibiofemoral kinematics following partial meniscectomy. The purpose of this study was to determine the effects of partial meniscectomy on cartilage compositional properties using T1 ρ and T 2 relaxation time mapping and to assess changes in tibiofemoral kinematics. It is hypothesize that abnormal tibiofemoral kinematics and relaxation time elevation (a reflection of changes in cartilage biochemical composition) in the weight-bearing regions of the knees following meniscectomy will be observed. Methods Nine patients (7 males and 2 females; mean age, 48.6 ± 10.8 years; BMI = 27.3 ± 3.8 kg/m 2 ) with tears of the posterior horn of the medial meniscus underwent arthroscopic partial meniscectomy. Pre-surgical and 6 months post-surgical MRIs were obtained in all subjects to evaluate cartilage relaxation times and tibiofemoral kinematics. Paired t tests were performed to determine significant changes in cartilage relaxation times from baseline. Results T 1ρ relaxation time in the region of the medial femoral condyle directly adjacent to the resection showed an increase of 7.4 % at 6 months ( p = 0.02). T 2 relaxation times in both the medial and lateral tibial plateaus showed significant elevation at 6 months. Consistent kinematic trends were not found in post-meniscectomized knees. Conclusions These results suggest that arthroscopic partial meniscectomy affects the biochemical composition of articular cartilage in the knee in as early as 6 months. The largest responses were observed in the weight-bearing regions and the cartilage immediately adjacent to the resection. This suggests that the loading environment has been altered enough to result in cartilage compositional changes in a very brief period of time following meniscectomy. Level of evidence IV.