chapter 3: History and Physical Examination

What is the Nature of the Pain?

Pain secondary to tissue overload from patellofemoral malalignment or to acute musculoskeletal injury is usually activity related. This does not mean that it will not hurt at rest, but it should be exacerbated with periods of increased activity. The pain is achy and sometimes even compared with a toothache. When patients complain of truly constant pain, not related to activity at all, one should be suspicious that the cause of the pain may not be entirely related to musculoskeletal structures. Possible causes of constant pain include postsurgical neuroma, referred neurogenic pain, reflex sympathetic dystrophy (RSD), symptom magnification or psychologic issues related to secondary gain from pain and perceived disability. In such cases, physical examination should focus on reproducing the patient's symptom and on evaluating the consistency and appropriateness of response to palpation. Exaggerated pain responses and pain with palpation everywhere around the knee make diagnosis difficult. Pain out of proportion to physical findings is the most reliable sign of potential RSD. The absence of classic vasomotor findings of RSD such as discoloration and temperature difference does not rule out RSD. O'Brien et al recently published a series of 60 patients with RSD of the knee proved by successful sympathetic blockade with no significant vasomotor findings in approximately one third (6). In the absence of RSD, exaggerated pain responses may be due to underlying psychosocial issues.

Some patients complain of sharp or burning pain. Constant burning pain indicates possible neuromatous origin. Sharp, intermittent and unpredictable pains suggest loose bodies in patients with a history of patellar instability because of the high incidence of osteochondral injury. Unstable chondral flaps can also cause similar symptoms. Pathologic hypertrophic synovial plicae classically are thought to cause medial catching and clicking but often seem to cause burning pain when acutely inflamed. Although analysis of the nature of a patient's pain cannot be pathognomonic of his/her disorder, thoughtful critique of the spontaneous complaints and responses to open‑ended questioning can help lead to accurate diagnosis.





Inside Chapter 3: