The Future of knee transplant surgery-Non-cemented Total Knee Arthroplasty

Cemented fixation for Total knee arthroplasty (TKA) has excellent long-term results and is the gold standard. The patient population undergoing TKA is becoming younger, more active, heavier, and living longer. Surgeons are facing the challenge to provide long-lasting constructs to this evolving population. However, longevity in the younger, heavier, and more active population is suboptimal with cemented fixation. There is a higher rate of aseptic loosening in this younger patient cohort, especially for patients under 55 years of age.

Modern cementless TKA implants have improved dramatically due to innovations in technology and design. Cementless fixation offers the possibility to gain biologic fixation, preserve bone stock, and potentially improve survivorship. Other potential advantages of cementless fixation include shorter surgical time, and less third body debris from loose cement particles. Disadvantages include lack of local antibiotic delivery, the need of good bone quality, and higher implant cost.

Samuel Rodriguez and Amar S. Ranawat did a retrospective review of all consecutive cementless TKA procedures performed at a single academic institution from 2016 until 2020. Demographics, aseptic revisions, and septic revisions were pulled from the electronic medical record. Inclusion criteria were patients age≥18 years undergoing primary TKA and receiving a cementless knee implant. A midline skin incision was used on all procedures using a medial parapatellar approach. All patients received the same preoperative antibiotic and postoperative anticoagulation protocols. The same physical therapy protocol was also used consisting of immediate weight bearing with active and passive exercises. Different cementless TKA prosthesis were used during the study period. Patient surgical variables including primary laterality, year of surgery, revision or not, time to first revision, and septic revision were also collected. The number of yearly implanted cementless TKA prosthesis was determined to analyse utilization trends.

Results

• Eight hundred fourteen patients received cementless TKA implants with a mean (± standard deviation [SD]) time to revision of 12.3±13.9 months, the mean (±SD) age was 61.6±7.8 years, and the mean (±SD) BMI was 32.1±6.0 kg/m2

• During the study period there were 4 septic revisions (0.49% septic failure rate), leaving 810 patients for potential aseptic failure. There were nine aseptic failures (1.11% aseptic failure rate) with different mechanisms of failure. Of these nine aseptic failures five were due to loosening, only one patient had BMI<30.

• There was a linear yearly upward trend of cementless TKA prosthesis implanted within the last 5 years at their institution (R2=0.81), with 2020 being the exception (Covid 19 pandemic effect).

The authors concluded that Cementless fixation is here to stay, and its use will continue to increase. Early and mid-term outcomes have been excellent thus far. Changing clinical practice takes time but we have already seen this transition take place in total hip arthroplasty. As technology and design continue to evolve, they believe it is a possibility.

Due to the retrospective nature of our study there are several limitations.

(1) There is a limited follow up period for the most recently performed surgeries leading to immortal time bias.

(2) They did not compare to cemented fixation or include functional outcomes as it was outside the scope of this study. Further reading:

The Future is Non‑cemented Total Knee Arthroplasty: Volume Trends at the Hospital for Special Surgery

Samuel Rodriguez, Amar S. Ranawat

Indian Journal of Orthopaedics (2021) 55:1096–1100

https://doi.org/10.1007/s43465-021-00508-0