Younger patients more likely to have severe post-TKA pain, study suggests

Poor pain outcomes were reported by 17% of patients younger than 60 years compared to 7% of patients aged 60 to 64 years.

Patients treated with total knee arthroplasty before age 60 years appear to experience more unexplained postoperative pain, a study suggests.

Ivan J. Brenkel, MD, FRCS, and colleagues at Queen Margaret Hospital in Dunfermline, Scotland, reviewed data for 462 knees in 385 primary TKA patients with at least 5-year follow-up. Patients averaged 69 years of age at the time of surgery. In all cases, surgeons used a medial parapatellar approach and implanted a DePuy press-fit condylar prosthesis.

After excluding 10 knees due to infection or revision, the researchers divided the remaining knees into two groups based on the pain outcomes measured using the American Knee Society Score. Of the 462 knees, 374 (81%) had a pain score of 1, indication no pain, and were included in the good pain outcome group. Another 50 knees (11%) had mild pain scores and were also excluded from the analysis, leaving 28 knees (6%) to comprise the poor pain outcome group. These poor outcome knees had moderate to severe pain, with scores ranging from 5 to 7, according to the study.

The researchers found that 17% of patients aged less than 60 years had poor pain outcomes compared to 7% of patients aged 60 to 64 years (P<.05), "with even less poor outcome knees represented in older age groups," the authors said.

"If these figures are extrapolated, then patients younger than 60 at TKA are more than twice as likely to report poor pain scores at 5-year follow-up than those older than 60," they said.

"The higher expectations expressed by younger surgical candidates, greater activity, and possibly increased prosthesis wear may explain this finding," the authors said. "Alternatively, older patients who have a higher incidence of comorbidity may have other pain that distracts their attention from their painful knee."

The researchers also found that 13% of patients having staged bilateral TKA reported poor outcomes following their first operation compared to 6% who had poor outcomes following their second surgery and just 2% of patients treated with simultaneous bilateral TKA (P<.01), according to the study.

"In addition, 17% of the group with a sacrificed cruciate ligament reported poor pain scores compared with only 6% from the group with a retained cruciate ligament," the authors said, noting the difference was statistically significant (P<.01), despite "relatively small numbers in the cruciate sacrificed group."

Poor pain was also reported by 13% of patients who received a lateral release, the authors noted.

"The data ... advocate avoidance of lateral release and retention of the [posterior cruciate ligament] at surgery; however, the authors cannot exclude the possibility of selection bias in this finding," they said.

For more information:
Elson DW, Brenkel IJ. Predicting pain after total knee arthroplasty. J Arthroplasty. 2006;21:1047-1053.