chapter 4:imaging the patellofemoral joint
Dye and Boll (52) pointed out that radionuclide imaging may be helpful in the evaluation of patients with patellar pain .(Fig. 4.32). As with arthrosis in other areas, one might expect that significant articular breakdown might result in a subchondral bone remodeling response in the patellofemoral joint. Also, if there is significant trauma to the patella, one might expect an osseous remodeling response, as suggested by Dye and Boll (52). Subsequently, and particularly if articular cartilage is disrupted, excessive stress on the patella may aggravate or perpetuate bone remodeling in the patella. This process could result in increased activity in the patella as determined by radionuclide scan.
Brill (53) noted that bone scans are usually not positive in young athletes who have complaints of anterior knee pain. In our opinion, this is not surprising, because we believe that many anterior knee pain problems, particularly in young athletes, are localized to the peripatellar retinacular structures and patellar tendon.
In the evaluation of patients with resistant anterior knee pain that has not responded to the usual nonoperative treatment, radionuclide scanning may be very helpful (54). Spotty tracer uptake in the central patella appears pathognomonic of chondromalacia patellae in older patients (55). Certainly, if one is contemplating a major decompression procedure with anteriorization of the tibial tubercle, it would be reasonable to determine for sure that there is a significant articular and subchondral osseous remodeling problem in the patella. Also, in those patients who do not have other objective findings regarding the patellofemoral joint, one may wish to obtain a bone scan to rule out the possibility of significant patellar disease. Following trauma, one may need to wait 18 to 24 months, as suggested by Dye and Boll (52), for equilibrium and homeostatic restoration of normal bone function. In short, the radionuclide scan may be helpful in a variety of patellofemoral pain problems that are resistant to accurate diagnosis.
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