Changes in articular cartilage in experimentally induced patellar subluxation

Abstract

Objectives-Patellar subluxation was experimentally induced in young rabbits and the resulting cartilaginous changes were observed over a prolonged period of time to determine histological changes in the subluxated patellar cartilage. Methods-The tibial tuberosity in 12 week old rabbits was laterally displaced and fixed to the tibia with wire to induce lateral patellar subluxation. Pathological changes in patellar cartilage were examined for 120 weeks after surgery using computed tomography and stereoscopic microscopy. Results-Eight weeks after surgery, changes in articular cartilage consisting of horizontal splitting of the matrix were observed in the intermediate zone and were presumed to have been caused by shearing stress applied to the patellar cartilage. The cartilaginous changes caused by patellar subluxation progressed very little over the 120 weeks. Very few rabbits presented with osteoarthritic changes in the patellofemoral joint, most probably because the stress resulting from the malalignment of the patellofemoral joint was mild enough to permit recovery. Conclusion-The mild, non-progressive pathological changes, in particular, basal degeneration, induced in this experiment in patellar cartilage were quite similar to the changes in articular cartilage seen in human chondromalacia patellae. (Ann Rheum Dis 1997;56:677-681) The term chondromalacia patellae is widely used to describe clinical symptoms that include anterior knee pain, unstable feeling in the knee, tenderness on the patella, and giving way, with softening or fibrillation of the articular cartilage of the patella. Many studies have investigated the aetiology, macroscopic pathology, arthroscopic findings, clinical symptoms, and treatment of chondromalacia patellae, but surprisingly few have described the microscopic pathology of the articular cartilage in chondromalacia patellae.

Chondromalacia induced by patellar subluxation: morphological and morphometrical aspects in rabbits

“…Several theories on the aetiology of the patellar chondromalacia have been discussed and among them we can mention as important factors: the trauma, morphological abnormalities and variations in the subchondral bone, and recent studies point out that the stress excess on the cartilage as the key factor for the initiation of the cartilage breakdown [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

“…By endovenous administration of benzodiazepine (Zoletil 50 -Virbac  of the Brazil S.A.) in doses of 0.15-0.20 ml/kg, rabbits had a right patellar subluxation provoked manually daily during 30 minutes for a period of two weeks. The subluxation of the right knee joint was confirmed with computerized tomography according to the description of Ryu et al, while the left knee joint was considered as a normal control [14].…”

“…To observe the modification of the structures in series a Tomograph of the third generation mark Hitachi model W450 was used, with technique specifications for production of the image of 120 kV (kilovolts), and 90 mA (milliamperes), filter number 2, zoom 1.6. The cuts were of 2 mm thickness [14][15][16][17][18][19][20][21].…”

Surgical model of osteoarthritis secondary to medial patellar luxation in dogs

“…The loss of the stabilization force of the quadriceps muscle group is hypothesized to cause angular and rotational deformities in the distal part of the femur and tibia which place abnormal stresses on the articular cartilage and CCL, and with the progression of time this may lead to the pathogenesis of OA in dogs with MPL. Saito et al (1991) and Ryu et al (1997) reported the progression of degenerative changes of articular cartilage in patellar luxation with time in a rabbit model of patellar luxation. Roy et al (1992) also reported OA in dogs with patellar luxation in a retrospective study.…”

A Biomechanical Perspective on Physical Therapy Management of Knee Osteoarthritis

“…68,74,96,136,148 The supposition that excessive patellofemoral joint stress plays a role in the genesis of patellofemoral joint disease is supported by animal studies that have provided histological evidence for surgically induced patella malalignment resulting in cartilage degeneration. 136,161 In addition, patella malalignment has been associated with manifestations of patellofemoral OA and higher rates of disease progression in large observational cohort studies.…”