An outcome study of chronic patellofemoral pain syndrome - Seven-year follow-up of patients in a randomized, controlled trial

Background We determined prospectively the long-term outcomes of nonoperati ve treatment of chronic patellofemoral pain syndrome, Methods: Of forty-nine patients in a prospective, randomized, double-blind study of unilateral chronic patellofemoral pain syndrome in the knee, forty -five were reexamined seven years after the initial trial of treatment, In the earlier trial, the short-term (six-month) effects of intra-articular in jections of glycosaminoglycan polysulfate combined with intensive quadricep s-muscle exercises were compared with those of injections of a placebo comb ined with exercises and with those of exercises alone. At seven years, the follow-up consisted of standardized subjective, functional, and clinical as sessments and muscle-strength measurements as well as magnetic resonance im aging, radiography, and bone-densitometry measurements of the knee, Results: At six months, complete subjective, functional, and clinical recov ery had occurred in almost three-fourths of the patients and, with the numb ers available for study, neither significant nor clinically important diffe rences among the three initial treatment groups were detected. The subjecti ve and functional parameters showed few changes between six months and seve n years; almost three-fourths of the patients still had full subjective and functional recovery at the time of the latest follow-up. However, accordin g to the physician's clinical evaluation, the number of patients who had no symptoms on the patellar compression and apprehension tests decreased over time, from forty-two (93 percent) and forty (89 percent) of forty-five pat ients at six months to thirty (67 percent) and thirty-one (69 percent) at s even years; these changes were significant (p = 0.002 and p = 0.023, respec tively). The number of patients who had crepitation on the patellar compres sion test increased over time, from twenty-six (58 percent) at six months t o thirty-six (80 percent) at seven years (p = 0.021), The physician's overa ll assessment showed a similar trend, with thirty-four patients (76 percent ) having had complete recovery at six months compared with thirty (67 perce nt) at seven years; however, with the numbers available, this change was no t significant (p = 0.420), Magnetic resonance imaging, performed for thirty -seven patients, revealed no abnormalities in twenty-four (65 percent), mil d abnormalities in four (11 percent), moderate abnormalities (a 25 to 75 pe rcent decrease in the thickness of the cartilage) in seven (19 percent), an d overt patellofemoral osteoarthritis in two (5 percent) at seven years. Conclusions: The seven-year overall outcome was good in approximately two-t hirds of the patients. However, the remaining patients still had symptoms o r objective signs of a patellofemoral abnormality.