A longitudinal study of the quantitative evaluation of patella cartilage after total knee replacement by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping at 3.0 T: preliminary results

OBJECTIVE

To characterize the quantitative changes of patella cartilage over time after total knee arthroplasty (TKA) by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping at 3.0 T.

METHOD

Twenty-six knees of 26 patients (23 women and three men, mean age, 75 years) with primary osteoarthritis and osteonecrosis of the knee underwent TKA with a zirconia ceramic implant in this prospective study. Twelve patients without patella resurfacing (NR group) and 14 patients with patella resurfacing (R group) had TKA with cemented fixation. The implant position was examined by radiograph, computed tomography (CT) and magnetic resonance imaging (MRI). The clinical scores were checked pre-operatively, 1 year post-operatively and at the final follow-up. Patella cartilage and its thickness were evaluated pre-operatively and 1 year after TKA by dGEMRIC and T2 mapping in the NR group only. Patella cartilage was divided into eight regions of interest: the deep and superficial layers of the outer lateral and medial half, and the inner lateral and medial half from the central ridge.

RESULTS

The implant position was appropriate in all cases and clinical scores were not significantly different between the two groups. The post-operative dGEMRIC value of the outer medial half superficial zone in the NR group was significantly decreased compared with the pre-operation value (P<0.05), whereas T2 mapping was not significantly changed in all zones. The cartilage thickness of the outer zone was significantly thinner post-operatively (P<0.05).

CONCLUSIONS

These findings indicate that osteoarthritic changes in the outer zone of patella cartilage occurred 1 year after TKA.

Enhancement of learning capacity and cholinergic synaptic function by carnitine in aging rats

The effects of a carnitine derivative, acetyl-L-carnitine (ALCAR), on the cognitive and cholinergic activities of aging rats were examined. Rats were given ALCAR (100 mg/kg) per os for 3 months and were subjected to the Hebb-Williams tasks and a new maze task, AKON-1, to assess their learning capacity. The learning capacity of the ALCAR-treated group was superior to that of the control. Cholinergic activities were determined with synaptosomes isolated from the cortices. The high-affinity choline uptake by synaptosomes, acetylcholine synthesis in synaptosomes, and acetylcholine release from synaptosomes on membrane depolarization were all enhanced in the ALCAR group. This study indicates that chronic administration of ALCAR increases cholinergic synaptic transmission and consequently enhances learning capacity as a cognitive function in aging rats.