Results of total knee arthroplasty for painless, stiff knees

Background: Stiff knees, like completely ankylosed or arthrodesed knees, can be painless. Total knee arthroplasty (TKA) for these painless, stiff knees is technically demanding. However, it can correct the alignment and advance the range of motion to improve quality of life. So, we reviewed the preoperative and postoperative results of functional and pain scores, range of motion (ROM) and complications in painless, stiff knees treated by TKA.

Methods: Fifteen painless, stiff knees underwent TKA from January 1998 to January 2017. The mean follow-up period was 15.4 (2.4-22.2) years. All the knees were completely ankylosed or arthrodesed. Clinical outcome and complications were evaluated using medical record review, serial plan radiography, ROM assessment, Knee Society score (KSS), Knee Society function score (FS), and a visual analog scale for pain (VAS).

Results: All patients were satisfied with their operated knees. Mean KSS and FS scores were improved from 36 and 50.9 to 76.9 and 67.2, respectively (P < 0.001 and P = 0.01). The mean ROM increased from 0º preoperatively to 77.6º (15-130) at the final follow-up (P < 0.001). The mean VAS had worsened from 0 preoperatively to 0.2 postoperatively, however it was not significant (P = 0.1). Major postoperative complications were reported in five of the knees (33.3%).

Conclusions: The results of TKA for painless, stiff knees were satisfactory with improved ROM and quality of life. Although some patients had mild pain and complications postoperatively, they were satisfied with the result. However, our study recommends that surgeons should consider the high rate of complications in the completely ankylosed or arthrodesed knees.

Level of evidence: A retrospective case series, Level IV.

Keywords: Ankylosis; Knee; Stiff; Total knee arthroplasty.