Similar outcomes of constrained condylar knee and rotating hinge prosthesis in revision surgery for extension instability after primary total knee arthroplasty

Novel post-cam endoskeleton-reinforced posterior-stabilized cement articulating spacer reduced the rate of mechanical complications in prosthetic knee infection

BACKGROUND

Posterior-stabilized cement articulating spacers (PS spacers) have superior knee scores and a greater range of motion in a two-stage exchange for chronic prosthetic knee infections (PKIs); however, mechanical complications are associated with the use of PS spacers. In the present study, we investigated a novel post-cam endoskeleton-reinforced PS spacer and its outcomes.

METHODS

This single-surgeon retrospective cohort study included patients with chronic PKIs treated with PS spacers between 2015 and 2022. PS spacers with three different configurations, based on endoskeleton reinforcement, were compared: non-reinforced (n-PS), cam-reinforced alone (C-PS), and post- and cam-reinforced (PC-PS). Rates of mechanical complications, reoperation, and infection eradication were evaluated. The constraint choice of the revision prosthesis and risk factors for mechanical complications were analysed.

RESULTS

In total, 186 patients, including 75 with n-PS, 61 with C-PS, and 50 with PC-PS spacers, were included. All patients were followed up for 2 years. The rate of overall mechanical complications was lowest in patients treated with PC-PS spacers, particularly in patients with unstable joints after femoral cam and tibial post fracture and tibial spacer dislodgement. Moreover, neither spacer exchange nor rotating-hinge knee revision prosthesis was required in PC-PS spacers. Independent risk factors for mechanical complications were body mass index ≥ 25 kg/m2, femoral spacer size ≤ 2, and intra-operative maximum flexion ≥ 110°.

CONCLUSION

The novel PC-PS spacers prevented mechanical complications, spacer exchange, and the need for high-level constraint revision prostheses. We recommend the use of novel PC-PS spacers in two-stage exchange for chronic PKIs, especially in patients with a high body mass index, small femoral spacer size, and high knee flexion.

Rate of complications and short-term Functional Results of Revision Total Knee Arthroplasty for Tibio-femoral Instability: do stability and range of motion are restored in 62 revisions

BACKGROUND

Tibio-femoral instability (TFI) due to ligament imbalance is a growing cause of revision total knee arthroplasty (TKA). The results are heterogeneous in the event of revision and literature is scarce regarding this issue particularly when use of hinge prostheses is not exclusive to manage this complication. Therefore, a retrospective investigation was conducted aiming to (1) analyze the one-year functional results, (2) determine the rate of complications after revision for TFI using posterior-stabilized or condylar constrained knees (CCK), 3) identify the factors that could influence the function outcome.

HYPOTHESIS

Patients undergoing revision TKA for TFI would show an improvement in Oxford Knee Score at one year postoperative.

METHODS

Sixty-two patients were included (40 females, 22 males) mean age 62,9 years ± 8.2 (range, 45,7-78,4). Instability was classified as instability in extension (n = 28), midflexion (n = 12), flexion (n = 12) or global (n = 15). Revisions were done because of isolated instability. Revision consisted in implant revision using a CCK (n = 42), a hinge prosthesis (n = 12) or an isolated polyethylene insert exchange (n = 8). Patients were assessed at one year by the difference between the preoperative Oxford Knee Score (OKS) and the score at one year postoperatively. The results were deemed satisfactory if the variation between preoperative OKS and one-year follow-up was greater than or equal to 5 points (Minimal Clinically Important Difference (MCID) following TKA). Complication rate and risk factors influencing the outcome were also analyzed.

RESULTS

Of the 62 patients, 59 could be assessed at one year using postoperative OKS (one death at 0.66 years from unrelated reason, and two had repeated revision within one year postoperative [1 aseptic loosening and 1 Co-Cr allergy]). Preoperative OKS was 15.5 points ± 7.1 (range, 2-37), rising to 28.9 points ± 8.7 (range, 11-45) at follow-up. The mean OKS improvement was 13.4 points ± 10.3 (range, -8 to 33) (p < 0.001) and 47 patients (79.6%) reached the MCID at follow-up. Female gender was associated with a worse evolution of OKS (-5.8, 95% CI: -11.26 to -0.34 (p = 0.038)). In contrast, there was no significant difference in the evolution of the OKS according to the type of TFI in extension or in flexion, in midflexion or global (p = 0.5). Likewise, there was no significant difference in the evolution of the OKS between RTKA using CCK, hinged prosthesis or isolated polyethylene insert exchange (p = 0.3). There was no recurrence of instability at final follow-up (3.04 years ± 1.5 (range, 0.66-6.25)). Revision for instability did not drive to stiffness since mean flexion prior to RTKA was 116 ° ± 13 ° (range, 90 ° to 130 °) versus 116.7 ° ± 12 ° (range, 90 ° to 130 °) at follow-up. Fourteen patients (22.6%) experienced postoperative complications, including 3 revisions (4.8%) at final follow-up.

CONCLUSION

RTKA for TFI leads to significant functional improvement at one-year postoperative. However, the risk of complications is almost high at 22.6%.

LEVEL OF EVIDENCE

IV; retrospective study.

Long-term results (after a mean 11.3years, and up to 22years, of follow-up) of the Legacy Constrained Condylar Knee (LCCK™) in primary total knee arthroplasty

INTRODUCTION

The use of a sliding prosthesis in total knee arthroplasty (TKA) with increased stress is an intermediate solution in primary surgery, between posteriorly stabilized prostheses and hinged prostheses, in cases of ligamentous laxity and/or loss of bone substance. Favorable results have been reported in the medium term but to our knowledge, this type of prosthesis has not been evaluated in Europe beyond 10 years of follow-up. We therefore conducted a retrospective study in order to carry out: 1) the study of the survival of the Legacy Constrained Condylar Knee (LCCK™) prosthesis in primary surgery, 2) the analysis of complications, functional scores and radiographic data, 3) the analysis of the link between the diaphyseal filling rate and prosthetic loosening.

HYPOTHESIS

The LCCK™ sliding prosthesis with increased constraint has equivalent long-term survival and clinical results to standard posteriorly stabilized TKA and superior to hinged TKA.

MATERIAL AND METHOD

A retrospective series of 141 LCCK™ implanted in 134 patients between 1997 and 2010 was analyzed. Survival was assessed with censoring through an evaluation of partial or total revision of the implants. The functional results were evaluated using the IKS and Oxford 12 scores. Data regarding the Canal Fill Ratio (CFR) and the presence of pathological periprosthetic lines were also collected.

RESULTS

The average follow-up was 11.3±5.3years with a maximum follow-up of 22.7years. Survival at 20years was 90.8% [95% CI: 83.7-95.7]. The rate of early complications was 13.5% (19/141), predominantly comprised of venous thrombosis (6/141), hematomas (3/141 including two requiring surgical drainage), stiffness (3/141) and early infections (3/141). The rate of late complications was 17% (24/141), led by stiffness (4.4%; 6/141), infections (2.9%; 4/141) and hardware failure (2. 2%; 3/141). Ten of the 141 patients (7.1%) had LCCK failure, including 3 (2.1%) for stiffness, 3 (2.1%) for hardware failure, 2 (1.4%) for infection, 1 (0.7%) for laxity and 1 (0.7%) for a periprosthetic fracture. No aseptic loosening was found. The total IKS score went from 65 [0-116] to 143 [79-200] at follow-up, the IKS knee score went from 30 [0-66] to 85 [44-100], and the IKS function score went from 35 [0-70] to 57 [0-100]. The Oxford score went from 14 [2-25] to 34 [15-48] at follow-up. Only two patients (1.4%) presented with a partial periprosthetic line. The tibial CFR was 0.81 and the femoral CFR was 0.76. The influence of the CFR could not be analyzed due to the absence of loosening.

DISCUSSION

The LCCK™ prosthesis in primary surgery has good medium-term survival, a significant improvement in functional scores and a complication rate comparable to posteriorly stabilized prostheses. The complication rate is lower than that of hinged prostheses.

LEVEL OF EVIDENCE

IV; single-center retrospective study.

Midterm results of modular hinge total knee arthroplasty using cementless osseointegrating stems: low fixation associated complications and good functional outcome in primary and revision knee arthroplasty

PURPOSE

This study aimed to investigate functional outcome and complications after primary and revision modular H-TKA using hybrid fixation with cementless stems.

METHODS

Between 2015 and 2018, 48 patients with 50 implants were included after hybrid implantation of a single design H-TKA system using cementless osseointegrating stems and modular components. Complications and clinical outcome were analysed using Knee Society Score (KSS), the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) and the Short-Form Health Survey 12 (SF-12) score.

RESULTS

Indications for implantation were aseptic revision (n = 29, 58%), primary TKA (n = 19, 38%) and two-stage septic revisions (n = 2, 4%). Complications were reported in 26% (n = 12), whereas complications associated with hybrid fixation occurred in 5 (10%) cases, with 2 (4%) requiring revision surgery for aseptic loosening and 3 (6%) treated with an adapted postoperative protocol for perioperative fractures. Implant survivorship was 84% after a mean follow-up of 54 months. Postoperative KSS significantly improved from 51.50 (12-100) to 78.36 (41-99; p < 0.001). The mean WOMAC score was 19.26 (0-55), SF-12 PCS was 41.56 points (22.67-57.66) and SF-12 MCS was 49.21 points (23.87-63.21).

CONCLUSION

Hybrid modular implantation in H-TKA provides satisfactory clinical and functional results in primary and revision TKA. Clinical outcomes significantly improve with reduced pain, increased mobility, and good-to-excellent functional scores after implantation. Whilst implant survival is comparable to previous studies and complications associated with hybrid fixation are low, general complication rates are comparably high.