phosphocreatine and Osteoarthritis

We tested the hypothesis that intrusion of the knee joint capsule alters quadriceps muscle metabolism and function independently from the damage induced to knee cartilage.. Adult rats were separated into four groups: intraarticular injections of saline (SAL; n=9); intraarticular injections of papain, a model for osteoarthritis (PIA; n=7); sham injections (SHAM; n=8); and controls (CTL; n=5). 31P magnetic resonance spectroscopy (31P-MRS) was performed after 2 weeks. Spectra were obtained from the left quadriceps: two at baseline, eight during electrical stimulation with simultaneous measurement of contractile force, and 15 during recovery. 31P-MRS data were presented as the ratio of inorganic phosphate (Pi) to phosphocreatine (PCr), concentrations of PCr [PCr], intramuscular pH, and the rates and time constants of PCr breakdown during stimulation and PCr recovery. Intramuscular cytokine concentrations were measured within the quadriceps. Histologic slides of the knees were scored for severity of cartilage damage.. The interventional groups produced values of Pi/PCr ratio, [PCr], contractile force and pH that were significantly different from CTL. These changes in muscle function were accompanied by higher concentrations of interleukin-1 observed with PIA and SAL. We did not observe any effect of cartilage damage on muscle function or metabolism.. Knee joint intrusion alters quadriceps muscle metabolism with accelerated depletion of energy stores and fatigue during stimulation. This study demonstrates that needle intrusion into the knee joint results in muscle dysfunction, independently from the extent of cartilage damage.

Topics: Animals; Cartilage, Articular; Cytokines; Female; Injections, Intra-Articular; Magnetic Resonance Spectroscopy; Models, Animal; Muscle Contraction; Osteoarthritis; Papain; Phosphocreatine; Phosphorus; Quadriceps Muscle; Rats; Sodium Chloride

It has been suggested that muscle ischemia could contribute to myositis ossificans and that the ischemia could result from prolonged retraction during surgery. Biopsy specimens of the gluteus medius muscle were taken at the beginning and the end of 30 primary total hip arthroplasties and the intracellular lactate and phosphocreatine (PCr) measured. Postoperative myositis ossificans was classified according to Brooker after 1 year, and the surface of the heterotopic bone projected above the greater trochanter in an anteroposterior roentgenogram was measured by planimetry. The findings suggest that muscle ischemia is not an important cause of myositis ossificans after hip arthroplasty, but elevated levels of lactate and lowered levels of intracellular PCr may occur as nonspecific responses to tissue trauma that through other mechanisms may lead to ossification.

Topics: Aged; Aged, 80 and over; Female; Hip Prosthesis; Humans; Ischemia; Lactates; Lactic Acid; Male; Middle Aged; Muscles; Myositis Ossificans; Osteoarthritis; Phosphocreatine; Postoperative Complications