Implant survival of 3rd-condyle and post-cam posterior-stabilised total knee arthroplasty are comparable at follow-up > 10 years: a systematic review.

PURPOSE: To summarise the literature on 3rd-condyle total knee arthroplasty (TKA) designs and compare their survival rates to those of post-cam TKA designs. The null hypothesis was that 3rd-condyle TKAs would have equivalent survival rates compared to contemporary post-cam TKAs. METHODS: An electronic literature search for Level I-V studies was independently conducted by two researchers using Medline® and Web of Science for studies published between January 1984 and October 2020 that specifically reported on rates of implant survival and complications, joint kinematics, clinical outcomes, and radiographic outcomes of 3rd-condyle TKA. The methodological quality of clinical studies was assessed according to the Downs and Black Quality Checklist for Health Care Intervention Studies, and for in vitro and in silico studies according to the Joanna Briggs Institute (JBI) tool for assessing analytical cross-sectional studies. Findings extracted for each TKA design were presented as reported and synthesised narratively. Survival rates at 5, 10 and > 10 years of 3rd-condyle TKA designs were graphically compared to rates of post-cam TKA designs published in joint registries. RESULTS: A total of 38 studies were identified that reported on kinematics, clinical outcomes, radiographic alignment, and rates of complications and survival. Mean survival rates ranged from 96 to 98% at 5 years, 78-100% at 5-10 years, and 86-99% at > 10 years for 3rd-condyle PS TKAs. Mean survival rates ranged from 93 to 98% at 5 years, 89-99% at 5-10 years, and 88-95% at > 10 years for post-cam PS TKAs. CONCLUSION: Implant survival rates of 3rd-condyle TKAs are comparable to those of post-cam TKAs at follow-up > 10 years. When compared to post-cam PS TKA, 3rd-condyle designs offer an alternative for younger and more active patients when considering the added benefits of a lowered point-of-contact and larger congruent contact area at the intercondylar tibial sulcus, that reduce risks of loosening and component wear. LEVEL OF EVIDENCE: V.

Results of a French multicentre retrospective experience with four hundred and eighteen failed unicondylar knee arthroplasties.

PURPOSE: By means of a multicentre retrospective study based on the failure of 418 aseptic unicondylar knee arthroplasties (UKA) our aims were to present the different types of revision procedure used in failed UKAs, to establish a clear operative strategy for each type of revision and to better define the indications for each type of revision. METHODS: Aseptic loosening was the principal cause of failure (n = 184, 44%) of which 99 cases were isolated tibial loosening (23.5 % of the whole series and 54% of all loosening), 25 were isolated femoral loosening (six and 13.6%) and 60 were both femoral and tibial loosening (14.3 and 32.6%). The next most common causes of failure were progression of arthritis (n = 56, 13.4%), polyethylene wear (n = 53, 12.7%), implant positioning errors (n = 26), technical difficulties (n = six) and implant failure (n = 16, 3.8% of cases). Data collection was performed online using OrthoWave software (Aria, Bruay Labuissiere, France), which allows collection of all details of the primary and revision surgery to be recorded. RESULTS: A total of 426 revisions were performed; 371 patients underwent revision to a total knee arthroplasty (TKA) (87%), 33 patients (7.7%) were revised to an ipsilateral UKA, 11 (2.6%) patients underwent contralateral UKA (ten) or patellofemoral arthroplasty (one) and 11 patients (2.6%) underwent revision without any change in implants. CONCLUSIONS: Before considering a revision procedure it is important to establish a definite cause of failure in order to select the most appropriate revision strategy. Revision to a TKA is by far the most common strategy for revision of failed UKA but by no means the only available option. Partial revisions either to an alternative ipsilateral UKA or contralateral UKA are viable less invasive techniques, which in carefully selected patients and in experienced hands warrant consideration.

Posterior slope of the tibial implant and the outcome of unicompartmental knee arthroplasty.

BACKGROUND: Laboratory studies have suggested that the sagittal displacements permitted by a knee replacement are influenced by the posterior slope of the tibial implant. The effect of the posterior slope of the tibial implant on the outcome of unicompartmental arthroplasty is not well known. The purpose of the present study was to assess the effect of the posterior slope on the long-term outcome of unicompartmental arthroplasty in knees with intact and deficient anterior cruciate ligaments. METHODS: We retrospectively reviewed the results of ninety-nine unicompartmental arthroplasties after a mean duration of follow-up of sixteen years. At the time of the arthroplasty, the anterior cruciate ligament was considered to be normal in fifty knees, damaged in thirty-one, and absent in eighteen. At the most recent follow-up, we measured the posterior tibial slope and the anterior tibial translation on standing lateral radiographs. The anteroposterior stability of seventy-seven knees that had not been revised by the time of the most recent follow-up was evaluated clinically. RESULTS: In the group of seventy-seven knees that had not been revised by the time of the most recent follow-up, there was a significant linear relationship between anterior tibial translation (mean, 3.7 mm) and posterior tibial slope (mean, 4.3 degrees ) (p < 0.01). The mean posterior slope of the tibial implant was significantly less in the group of seventy-seven knees without loosening of the implant than it was in the group of seventeen knees with loosening of the implant (p < 0.05). Five ruptures of the anterior cruciate ligament occurred in knees in which the ligament had been considered to be normal at the time of implantation; the posterior tibial slope in these five knees was > or = 13 degrees. Clinical evaluation revealed normal or nearly normal anteroposterior stability at the time of the most recent follow-up in all sixty-six unrevised knees in which the anterior cruciate ligament had been present at the time of implantation. Of the eighteen knees in which the anterior cruciate ligament had been absent at the time of the arthroplasty, eleven still had the implant in situ at the time of the most recent follow-up; the mean posterior tibial slope in these eleven knees was <5 degrees. Seven knees in which the anterior cruciate ligament had been absent at the time of the arthroplasty were revised. In these knees, the tibial prosthesis was implanted with a posterior slope of >8 degrees. CONCLUSIONS: These findings suggest that >7 degrees of posterior slope of the tibial implant should be avoided, particularly if the anterior cruciate ligament is absent at the time of implantation. An intact anterior cruciate ligament, even when partly degenerated, was associated with the maintenance of normal anteroposterior stability of the knee for an average of sixteen years following unicompartmental knee arthroplasty. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.