Tip-of-Stem Pain Is a Rare Complication Following Revision Total Knee Arthroplasty at a Mean 6.9-Year Follow-Up

Tip-of-stem pain is a rare complication of revision total knee arthroplasty (TKA). This study evaluates the incidence of tip-of-stem pain and its associations with clinical and radiographic outcomes in revision TKA.

A total of 910 patients who underwent stemmed revision TKA between January 2012 and December 2022 were identified for our retrospective review. Stem length, width of isthmus, and distance from tip-of-stem to isthmus were collected and compared between patients who did and did not have stem pain. Mann-Whitney U-tests, independent t-tests, Chi-square tests, and Fisher exact tests were used to evaluate the association between radiographic outcomes and tip-of-stem pain.

Of 910 patients, 3.0% reported tip-of-stem pain. Of these, 2.9% presented with tibial and 0.6% presented with femoral stem pain. The mean distance between the stem tip and the tibial isthmus was significantly shorter in patients who had versus those who did not have stem pain (P < 0.001). Longer tibial stems were associated with stem pain, as 100% of patients who had tibial stem pain had a tibial stem length of 100 mm or more (P = 0.004). Mean femoral length was significantly shorter in patients who had stem pain (P = 0.0373). There was no significant difference in tibial length, tibial width, femoral width, femoral stem length, or distance from the tip of the stem to the femoral isthmus observed between patients who had or did not have stem pain. Overall, 88.9% of patients experienced improvements in stem pain following nonoperative measures, with 59.3% experiencing complete resolution of pain. The revision rate of patients who had stem pain was 14.8%, with all revisions attributed to reasons other than tip-of-stem pain.

Despite a low incidence, understanding certain radiographic variables associated with tip-of-stem pain may guide surgeons in the most appropriate stem length, diameter, and design.