Evaluating Outcomes of Cemented vs. Cementless TKA
With a significant number of failures from lack of bony ingrowth, early studies of cementless total knee arthroplasty (TKA) were not promising: In 2000, a study presented by Fehring et al at the annual meeting of the American Association of Hip and Knee Surgeons showed a 13% failure rate.
But most early studies pertained to 20-year-old prosthesis designs. Newer cementless designs use improved porous foam materials and adjunct surface coatings that are intended to provide secure initial fixation and improved bony ingrowth.
Are they doing what they’re supposed to do? In other words, are patients getting better outcomes?
To find out, Nam et al compared clinical outcomes at a minimum of 2 years in 120 TKA patients age 18 to 74 who were randomized to receive either the cemented (n=56) or the cementless (n=64) version of the same cruciate-retaining implant. The only difference between the implants was the highly porous fixation surfaces of the cementless design.
Patients were asked to rate their new knee as a percentage of normal (100% = normal) at least 2 years after surgery. The researchers also collected Knee Society (KSS), UCLA, Oxford Knee, and Forgotten Joint scores.
Clinical outcomes measures did not differ significantly between groups, and patients with the cementless design rated their knee similar to patients with the cemented design: 87.6+13.8% in the cementless group versus 87.0+12.3% in the cemented group (P=0.8). Neither group had evidence of component loosening on radiographs.
The researchers suggested that although the cementless TKA implant demonstrated excellent results, further surveillance is necessary to determine long-term benefits of this design.
Nam D, Lawrie CM, Salih R, Nahhas CR, Barrack RL, Nunley RM. A Prospective, Randomized Trial of Cemented vs. Cementless Total Knee Arthroplasty of the Same, Modern Design (Paper #3). Presented at the 2018 Annual Meeting of the American Association of Hip & Knee Surgeons, November 1-4, 2018, Dallas, Texas.