Stiffness complaints after total knee arthroplasty (TKA) are frequent, yet poorly understood and can be challenging for surgeons to address. The WOMAC stiffness subscale is a widely used measure of stiffness and can serve as a simple screening tool for complaints.
We aimed to identify a threshold for stiffness complaints on the WOMAC stiffness subscale and investigate its overlap with range of motion (ROM) in TKA patients.
TKA patients were enrolled preoperatively and followed for 6 months. At follow-up, patients reported their ROM, completed the WOMAC stiffness subscale (range 1–8 with 8 continuous stiffness) and indicated whether they experienced more stiffness than expected. To identify a threshold for complaints, we compared patients’ WOMAC stiffness scores to when they experienced more stiffness than expected, visually, and statistically. We also mapped ROM limitations at 6 months to WOMAC stiffness scores. Finally, we determined if baseline characteristics were associated with stiffness complaints.
Two hundred and forty-six TKA patients were enrolled preoperatively with 82% follow-up rate at 6 months. Our results showed that patients with a WOMAC stiffness score = 3+ were significantly more likely to experience more stiffness than expected. Patients reporting full ROM (54%) reported a wide range of WOMAC stiffness subscale scores (1–6). Baseline WOMAC pain and function scores were the only factors associated with stiffness complaints.
ROM is a poor surrogate of patient-reported stiffness, and the patients’ perception of “stiffness” is clearly more complex than just ROM. We identified a WOMAC threshold that could potentially easily serve this purpose.
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Conflict of Interest
Christina Herrero, Alejandro Gonzalez Della Valle, MD and Geoffrey H. Westrich, MD have declared that they have no conflict of interest. Hassan M.K. Ghomrawi, PhD, MPH reports institutional grants from the National Institute of Child and Human Development (National Institutes of Health career development grant [R00 HD060686]) and the Agency of Health Research and Quality through a Center for Education and Research on Therapeutics grant (CERTs; Agency of Healthcare Research and Quality RFA-HS-05-14) during the conduct of the study. Carol A. Mancuso, MD reports grants from Hospital for Special Surgery, during the conduct of the study; grants from NHLBI, AHRQ, NIA—through internal Cornell award, outside the work.
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5).
Informed consent was obtained from all patients for being included in the study.
The study was partially funded by the generous donation of Mr. Glenn Bergenfield and The Sidney Milton and Leoma Simon Foundation.
Parts of this work were presented at the 2013 Knee Society closed meeting.
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Level of Evidence: Level I, prognostic study.
This work was performed at Hospital for Special Surgery and Weill Cornell Medical College, New York, NY, USA.
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Ghomrawi, H.M.K., Mancuso, C.A., Gonzalez Della Valle, A. et al. Is There a Threshold for Stiffness Complaints Following TKA on the WOMAC Stiffness Subscale?. HSS Jrnl 12, 145–149 (2016). https://doi.org/10.1007/s11420-016-9489-5
- total knee arthroplasty