Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes. Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty. This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice. Cite this article: Bone Jt Open 2021;2(1):48–57.

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Background: Patients undergoing unicompartmental knee arthroplasty (UKA) often want to return to sport (RTS) after surgery. However, the time taken to RTS and proportion of patients who RTS after UKA remain unknown. Purpose: To determine the time to RTS and proportion of patients who RTS after UKA. Study Design: Systematic review; Level of evidence, 4. Methods: A search was performed using PubMed, Medline, Embase, SPORTDiscus and the Cochrane Library databases for clinical trials reporting on RTS after UKA published between database inception and September 2021. In addition, a manual search was performed of relevant sports medicine and orthopaedic journals, and bibliographies were reviewed for eligible trials. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were used to undertake this study. Results: This meta-analysis included 11 studies (749 patients) that reported on RTS after UKA. The proportion of patients returning to sports increased over time: 6 studies (432 patients) demonstrated an overall pooled proportion of 48.1% (95% CI, 36.3%-60.2%) of patients who returned to sport at 3 months after surgery, while 7 studies (443 patients) demonstrated an overall pooled proportion of 76.5% (95% CI, 63.9%-87.1%) of patients who returned to sport at 6 months after surgery. Overall, 92.7% (95% CI, 85.8%-97.4%) of 749 patients were able to RTS at 4 years after surgery. Overall excellent patient-reported functional outcomes scores and low risk of complications with RTS after UKA were reported. Conclusion: The authors found that 48.1% of patients were able to RTS at 3 months after surgery and 76.5% were able to RTS at 6 months after UKA. Pooled proportion analysis showed that >90% of patients undergoing UKA were able to RTS at 48 months after surgery. The majority of patients who were able to RTS after UKA did so at a lower level of intensity than their preoperative level. RTS after UKA was associated with good patient-reported functional outcomes scores and a low risk of complications.