Semiconstrained posterior-stabilized total knee arthroplasty: indications, risks and benefits in primary and revision
Philippe Moisan1, Bardia Barimani2, Mohammed Al Kindi1
1From the Faculty of Medicine, McGill University, Montréal, Que. (Moisan); the Department of Orthopedic Surgery, McGill University, Montréal, Que. (Barimani, Al Kindi); and the Department of Orthopedic Surgery, Saint Mary's Hospital, Montréal, Que. (Mutch, Albers).
Background:
The constrained posterior-stabilized (CPS) implant for use in total knee arthroplasty (TKA) has a constraint level midway between that of a posterior-stabilized implant and a valgus-varus-constrained implant; there is currently no consensus on the surgical indications for use of this degree of constraint. We present our experience using this implant at our centre.
Methods:
We reviewed the charts of patients who received a CPS polyethylene insert during TKA in our centre between January 2016 and April 2020. We collected patient demographic characteristics, surgical indications, pre- and postoperative radiographs, and complications.
Results:
A total of 85 patients (74 females and 11 males with a mean age of 73 yr [standard deviation 9.4 yr, range 36-88 yr]) (85 knees) received a CPS insert over the study period. Of the 85 cases, 80 (94%) were primary TKA and 5 (6%) were revision TKA. The most common indications for primary CPS use were severe valgus deformity with medial soft-tissue laxity (29 patients [34%]), medial soft-tissue laxity without substantial deformity (27 [32%]) and severe varus deformity with lateral soft-tissue laxity (13 [15%]). The indications for the 5 patients who underwent revision TKA were medial laxity (4 patients) and an iatrogenic lateral condyle fracture (1 patient). Four patients had postoperative complications. The 30-day return to hospital rate was 2.3% (owing to infection and hematoma). A single patient required revision surgery for periprosthetic joint infection.
Conclusion:
We found excellent short-term survivorship of the CPS polyethylene insert when used for a spectrum of coronal plane ligamentous imbalances with or without pre-operative coronal plane deformities. Long-term follow-up of these cases will be important to identify adverse outcomes such as loosening or polyethylene-related problems.
