Bicruciate-retaining (BCR) designs for total knee arthroplasty (TKA) have been used since the 70s, but none of them have significantly grown in popularity. Therefore, there is a lack of information concerning BCR TKA, notably regarding the outcome and complications associated with this type of surgery.

The goal of this project is to study the results observed following the implantation of a BCR prothesis using a spacer-based gap balancing technique and to assess if some preoperative factors are associated with a worse prognosis.

A retrospective review of BCR TKAs performed by a single surgeon between June 2009 and June 2018 was conducted. Knees with a minimum of one-year follow-up were included in this study, with the exception of two knees that underwent a revision before the 1-year mark and were included for analysis. Patients were followed at six weeks, six months, one year, and then every following year post-operatively, and filled questionnaires (Knee Society and KOOS) at every visit. Clinical and radiological assessments included ROM, knee alignment, pain, and complications as defined by the Knee Society’s Standardized list and definition of Complication of Total Knee Arthroplasty.

A cohort of 207 knees in 194 patients (55 males, 139 females) was analyzed. The mean age was 65 (46-92), the mean BMI was 32.4 (standard deviation: 6.3) and the mean follow-up was 40.5 months (2.1-103.1). Forty-three knees (20.8%) suffered major complications. Twenty-one knees (10.1%) underwent revision at an average of 32.1 months after the index procedure. Revision-free survival at 100 months was 90.0% (95% confidence interval 85.8-94.3%). Revision was performed for aseptic tibial loosening in eight knees (3.9%) and stiffness in five knees (2.4%). Twenty-eight knees (13.5%) had further surgery other than revision, the most frequent procedure being manipulation under anesthesia (MUA) in 14 knees (6.8%). Minor complications included tendonitis (22.2%), persistent synovitis (6.8%), and superficial wound infections (6.3%).

All outcomes scores were greatly improved at the one-year follow-up compared to preoperatively (p<0.001). However, mean maximum flexion at the last follow-up was significantly reduced compared to preoperatively (120 degrees (80-150) vs 130 degrees (80-160), p <0.001). Furthermore, in patients that had a maximum flexion of less than 90 degrees at the six-week follow-up, the maximum flexion did not increase more at the last follow-up for patients who chose to undergo MUA than for patients who chose not to (p=0.327).

Aseptic tibial loosening was associated with an hypercorrection in varus of preoperative valgus knees (p=0.012). Indeed, while the knees of the rest of the cohort were in average corrected surgically from a preoperative varus to a neutral alignment of 180 degrees, an iatrogenic alignment in varus was associated with loosening of the tibial component in the knees that required revision.

In conclusion, this study identifies important factors that can explain failed BCR TKA and guide its use, particularly regarding surgical techniques and exclusion criteria.