Hybrid fixation of unicompartmental knee arthroplasty shows equivalent short-term implant survivorship and clinical scores compared to standard fixation techniques.

INTRODUCTION: There is a paucity of data regarding hybrid-fixated unicompartmental knee arthroplasty (UKA), and no study directly compared all three available fixation techniques (cementless, cemented, and hybrid). The hypothesis was that hybrid fixation might have a lower incidence of radiolucent lines (RLL) than cemented UKA, with equivalent outcomes to uncemented UKA. MATERIALS AND METHODS: A total of 104 UKA with a minimal follow-up of 1 year were retrospectively included, of which 40 were cemented, 41 cementless, and 23 hybrid prostheses. The functional outcomes scores included the Oxford Knee (OKS), Subjective Knee (SKS), and Forgotten Joint scores (FJS). RLLs, subsidence, and component positioning were assessed on radiographs. RESULTS: At a mean follow-up of 28 months, the survival rate was 95% for cemented UKA and 100% for the cementless and hybrid UKA (n.s.), respectively. Postoperative FJS (93 vs. 82 points, p = 0.007) and SKS (4.7 vs. 4.1 points, p = 0.001) were better in cementless than cemented UKA, with hybrid-fixated UKA in between the two (90 and 4.4 points, n.s.). Improvement of OKS preoperatively to postoperatively did not differ between the groups (n.s.). RLLs were more frequent in cemented (23%) compared to cementless (5%, p = 0.021) and hybrid UKA (9%, n.s.). With an incidence of 12%, subsidence occurred more commonly in cementless UKA compared to cemented (5%) and hybrid (0%) (n.s.) UKA. CONCLUSION: Hybrid fixation achieves equivalent results to standard UKA fixation techniques regarding implant survival and functional and radiological outcomes. Therefore, the hybrid fixation technique seems to be a valuable alternative as it combines the advantages of cemented tibial components with those of uncemented femoral components. LEVEL OF EVIDENCE: III.

Reduced Permanent Pacemaker Implantation in Patients With Stentless Freedom SOLO Compared With Stented Perimount Magna Aortic Bioprostheses: A Propensity Score Weighted Analysis.

OBJECTIVES: Postoperative permanent pacemaker implantation (PPI) after conventional aortic valve replacement (AVR), due to new-onset severe conduction system disorders, is required in approximately 7% of patients. This study investigated the need for PPI after AVR with conventional stented Perimount Magna compared with the Freedom SOLO (FS) stentless valve (Sorin Group, Saluggia, Italy), now LivaNova plc (London, UK) that uses a strictly supra-annular, subcoronary running suture implantation technique, sparing the vulnerable interleaflet triangles in the region of the septum membranaceum. METHODS: A total of 413 consecutive patients (71.4±9.2 yrs, 178 [43.1%] female) underwent isolated AVR using the stented Perimount Magna (n=264) or the stentless FS (n=149) bioprosthesis. Propensity score weighted analysis was used to account for patient-specific and procedural-specific variables, and to identify the prosthesis-specific need for early postoperative PPI within 30 days of AVR. RESULTS: Twenty (20) patients required PPI, which was associated with longer intensive care unit (2.1±1.7 vs 1.5±3.0 days, p<0.001) and overall hospital stays (13.8±5.2 vs 10.7±5.3 days, p<0.001) compared with no PPI. Propensity weighted logistic regression including cross-clamp times identified that use of the stented Perimount Magna was associated with increased need for PPI, as compared with the FS, with an odds ratio 5.8 (95% CI, 1.09-30.76; p=0.039). CONCLUSIONS: After corrections for all plausible confounders, AVR with the stented Perimount valve was associated with an odds ratio of almost 6 for an increased early postoperative need for pacemaker implantation compared with the FS stentless valve. This finding can be explained by the conventional implantation technique, which is potentially associated with mechanical trauma to the conducting system.

Freedom SOLO-Associated Thrombocytopaenia is Valve-Dependent and Not Due to In Vitro Pseudothrombocytopaenia.

BACKGROUND: Use of the Freedom SOLO (FS) stentless aortic bioprosthesis is limited by a unique and as yet unexplained severe decrease in postoperative platelet count in the absence of FS-related excess bleeding or thromboembolism. We investigated whether anticoagulant-associated pseudothrombocytopaenia could explain this complication. METHODS: Thirty consecutive patients (mean age 75.4±7.7 years, 11 [36.7%] female) underwent elective aortic valve replacement (AVR) with either the stented bovine Mitroflow (MF, n=18) or the stentless bovine FS (n=12) aortic valve bioprostheses. Serial platelet counts were performed simultaneously with sampling tubes containing tripotassium (K3-)-EDTA, trisodium (Na3)-citrate, or novel alternative magnesium sulfate (MgSO4, ThromboExact™)-based anticoagulant, respectively. RESULTS: Postoperative platelet counts decreased compared with preoperative values in all patients (p<0.001), but were significantly lower in patients receiving FS compared to MF at all measurement time points until the end of observation (day 9). Lowest platelet counts were seen on the first postoperative day for MF (mean reduction: -41.5%) and on the second postoperative day for FS (mean reduction: -59.9%). Postoperative platelet counts did not correlate with any of the anticoagulants, thereby indicating no pseudothrombocytopaenia in the study population. There was no interaction between anticoagulant and type of valve. Only 1% of variance in platelet counts was caused by the anticoagulant, 46% by the day of measurement relative to baseline, and 20% was caused by the type of valve. CONCLUSIONS: The platelet-lowering effect in patients receiving the FS is valve-dependent and is not caused by systemic preanalytical (laboratory) measurement error such as anticoagulant-dependent pseudothrombocytaemia, particularly with EDTA and citrate.

Surgical Outcomes and Analysis of Quality of Life Following Knee Arthroplasty in Very Elderly Patients.

In an aging population, the incidence of severe knee osteoarthritis in very elderly patients increases, leading to functional impairment and loss of independence. Knee replacement could be an effective treatment but is often denied due to fear of increased complication rate with advanced age. The objective of this study was to investigate complication rate, mortality, clinical outcome, and quality-adjusted life years (QALYs) of primary knee replacement in very elderly patients, defined as 83 years or older. Medical records of 85 cases, receiving a primary total (total knee arthroplasty [TKA]) or unicompartmental (unicompartmental knee arthroplasty [UKA]) knee replacement, aged 83 years or older at the time of surgery, were retrospectively reviewed for surgical and medical complications as well as survivorship. Functional outcome was obtained by Oxford Knee Score (OKS) and QALY. At a mean follow-up of 21 months (TKA) and 24 months (UKA), surgical and medical complication rates were 9.7 and 8.1% for TKA and 4.3 and 4.3% for UKA, respectively. One-year survival rate was 98.4% in TKA and 98.8% in UKA, the 5-year survival rate was 83.1 and 86.6%, respectively. OKS improved from 19 to 41 points in TKA and 23 to 40 points in UKA. Mean QALYs were 4.1 years for TKA and 3.9 years for UKA. TKA and UKA are safe and reliable surgical procedures in treating end-stage osteoarthritis in very elderly patients. Patients might benefit from improved pain, function, and quality of life. The mortality rate and overall complication rate were low, although slightly higher than reported in cohorts with younger patients. If the patient is suitable, UKA might be preferred over TKA, as the complication rate was significantly lower. Patients should not be excluded from knee replacement based on their age alone, but careful patient selection, peri- and postoperative optimization, and awareness for complications are quintessential for successful treatment.