Sources of sensory innervation of the hip joint capsule in the rabbit - a retrograde tracing study

The aim of the study was to investigate the sensory innervation of the hip joint capsule in the rabbit. Individual animals were injected with retrograde fluorescent tracer Fast Blue (FB) into the lateral aspect of the left hip joint capsule (group LAT, n = 5) or into the medial aspect of the hip joint capsule (group MED, n = 5), respectively. FB-positive (FB+) neurons were found within ipsilateral lumbar (L) and sacral (S) dorsal root ganglia (DRG) from L7 to S2 (group LAT) and from L6 to S4 (group MED). They were round or oval in shape with a diameter of 20-90 μm. The neurons were evenly distributed throughout the ganglia. The average number of FB+ neurons was 16 ± 2.8 and 27.6 ± 3.5 in rabbits from LAT and MED, respectively. The largest average number of FB+ neurons in animals of group LAT was found within the S1 DRG (8 ± 1.7), while S2 ganglion contained the smallest number of the neurons (3.6 ± 1). In the L7 DRG, the average number of FB+ neurons was 6.2 ± 1.6. In rabbits of MED group, the largest number of FB+ neurons was found within the S1 DRG (13.4 ± 4), while the smallest one was found within the S3 ganglion (1.4 ± 0.4). In L6, L7, S2 and S4 ganglia, the number of retrogradely labelled neurons amounted to 1.6 ± 0.5, 4 ± 1.5, 4.4 ± 1.5 and 2.8 ± 1.7, respectively. The data obtained can be very useful for further investigations regarding the efficacy of denervation in the therapy of hip joint disorders in rabbits.