Background
Articular cartilage normally functions as a load-bearing resistant material in joints. Patella is composed of hyaline cartilage and spongy bone. Chondrocytes form only 1–5% volume of the articular cartilage. They receive their nutrition by diffusion through the matrix. The alteration in articular cartilage become apparent following immobilization, from 4 to 6 weeks. Until now, focus of research has been the whole cartilage. Zonal changes have not been studied in detail. Since superficial zone bears maximum load and is the first zone to come in contact, the present study was designed to determine changes in thickness on immobilization and remobilization in superficial zone after dividing it into proximal, central, and distal segments.
Materials and Methods
Forty male rats belonging to Sprague Dawley strain were divided into two groups. Group 1 (n=20) subdivided into an experimental subgroup of 10 rats that were immobilized in plaster of Paris (POP) for 4 weeks and a control subgroup of 10 that were not immobilized. Group 2 (n=20) subdivided into an experimental subgroup of 10 rats that were immobilized for 4 weeks and remobilized for next 4 weeks and a control subgroup of 10 animals that were not immobilized. At the end of the experimental period, the knee joint was dissected and was cut in sagittal plane. The section was fixed in 10% formalin for 48 hours. Specimen was decalcified using ethylenediaminetetraacetic acid (EDTA). The paraffin blocks of 7 µm sections were cut and stained by H and E stain for routine histology and Alcian blue stain and Mallory Trichrome for fine structural microscopy. The zones were named as superficial transitional, radial, and hypertrophic according to the shape of cells present in each zone. The superficial zone was divided into superior part, central, and inferior parts. These parts were labeled as central, proximal, and distal segments. The calibrated stage micrometer was used to calibrate the ocular micrometer under objectives of different power. The ocular micrometer was placed inside the ocular lens. It was calibrated with the stage micrometer under objective lenses of different power. The number of divisions of ocular covering each zone was calculated. These divisions were converted into micrometer and the actual thickness was calculated.
Results
The significant decrease in thickness of superficial zone in proximal, central and distal segment was observed in experimental group in comparison to control group. When the experimental subgroup of group 2 was compared with experimental subgroup of group 1 (group immobilized for 4 weeks), no significant reversal was seen in superficial zone and instead significant decrease was observed in distal segment. Fibrous connective tissue was increased adjacent to superficial zone.
Conclusion
Each segment of superficial zone behaves differentially on immobilization and remobilization. Perhaps a much longer duration of remobilization is required to reverse changes of immobilization in articular cartilage and plays a significant role in knee joint movements.
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References
Jadin K, Wong B, Baeg W, Williamson A, Schuma B. Depthvarying density and organization of chondrocytes in immature and mature bovine articular cartilage assessed by 3D imaging and analysis. J Histochem 2005;53:1109–19.
Arendt E. Anatomy and malalignment of the patellofemoral joint: its relation to patellofemoral arthrosis. Clin Orthop Relat Res 2005;436:71–5.
Tatari H. The structures, physiology, and biomechanics of articular cartilage: Injury and repair. Acta Orthop Traumatol Turc 2007;41:1–5.
Watrin A, Ruaud JP, Olivier PT, Guingamp NC, Gonord PD. T2 mapping of rat patellar cartilage. Radiology 2001;219:395–02.
Hyc A, Osieckalwan A, Jozwiak J, Moskalewski S. The Morphology and selected biological properties of articular cartilage. Ortop Traumatol Rehabil 2001;3:151–6.
Mary CP, Mary AC. Effects of lengthened immobilization on functional and histochemical properties of rabbit tibialis anterior muscle. Exp Physiol 1992;77:433–42.
Vanwanseele B, Lucchinetti B, Stussi E. The effects of immobilization on the characteristics of articular cartilage: current concepts and future directions. Osteoarthritis Cartilage 2002;10:408–18.
Kannus P. Remobilization and prevention of immobilization atrophy. J Musculoskelet Neuronal Inter Articular Cartilage 2006;6:284–90.
Evans EB, Eggers G, James KB, Johanna BP. Experimental Immobilization and Remobilization of Rat Knee Joints. Acta Orthop Scand 2002;73:335–43.
Dowthwaite GP, Bishop JC, Redman SN, Khan IM, Rooney P. The surface of articular cartilage contains a progenitor cell population. J Cell Sci 2004;117:889–97.
Philip D, James D. Clinical evaluation of the effects of immobilization followed by remobilization and exercise on the metacarpophalangeal joint in horses. Am J Veterinary Res 2002;63:282–8.
Waddod AA. Effects of experimental immobilization with or without forceful compression of femoral articular cartilage. Pak Armed Forces Med J 2002;52:6.
Newton PO, Woo SL, Mow VC, Kenna DA, Akeson WH. Immobilization of the knee joint alters the mechanical and ultrastructural properties of the rabbit anterior cruciate ligament. J Orthop Res 1995;13:191–200.
Mikic B, Johnson TL, Chabra AB. Differential effects of embryonic immobilization on the development of fibrocartilaginous skeletal elements. J Rehabil Res Dev 2000;37:127–34.
Jortikka MO, Inkinen RI, Tammi MI, Parkkinen JJ, Haapala J, Kiviranta I, et al. Immobilization causes long lasting matrix changes both in immobilized and contralateral cartilage. Ann Rheum Dis 1997;56:255–60.
Salsich GB, Perman WH. Patellofemoral joint contact area is influenced by tibiofemoral rotation alignment in individuals who have patellofemoral pain. J Orthop Sports Phys Ther 2007;37:521–8.
MacIntyre NJ, Hill NA, Fellows RA, Ellis RE, Wilson DR. Patellofemoral joint kinematics in individuals with and without patellofemoral pain syndrome. J Bone Joint Surg Am 2006;88:2596–605.
Powers CM, Ward SR, Fredericson M, Guillet M, Shellock FG. Patellofemoral kinematics during weight-bearing and nonweight- bearing knee extension in persons with lateral subluxation of the patella: A preliminary study. Jo Orthop Sports Phys Ther 2003;33:677–8.
Chen CT, BurtonWurster N1, Lust G, Bank RA, TeKoppele JM. Compositional and metabolic changes in damaged cartilage are peak-stress, stress-rate, and loading-duration dependent. J Orthop Res 1999;17:870–9.
Fu LL, Maffulli N, Yip MK, Chan KM. Articular cartilage lesions of the knee following immobilization or destabilization for six or twelve weeks in rabbits. Clin Rheumatol 1998;17:227–33.
Samina A, Liaqat AM, Azhar M. Effects of free mobility verses restricted mobility on the degenerative changes induced by immobilization on the femoral articular cartilage of Rabbit knee. Pak Armed Forces Med J 2008.58:189–96.
Hagiwara Y, Ando A, Chimoto E, Saijo Y, Ohmori-Matsuda K, Itoi E. Changes of articular cartilage after immobilization in a rat knee contracture model. J Orthop Res 2008;27:236–42.
Luke KI. The nutrition of articular cartilage and its method of repair. Br J Surg 2005;12:31–42.
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Iqbal, K., Khan, Y. & Minhas, B.L.A. Effects of immobilization on thickness of superficial zone of articular cartilage of patella in rats. IJOO 46, 391–394 (2012). https://doi.org/10.4103/0019-5413.98826
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DOI: https://doi.org/10.4103/0019-5413.98826