Insights into complications after unicompartmental knee arthroplasty

Abstract

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Core Tip: In his study, Zhao et al offers a detailed analysis of the causes of primary revision after unicompartmental knee arthroplasty. The research highlights the significance of meticulous preoperative assessment, precise implant positioning, and ongoing education for healthcare providers to mitigate risks and improve outcomes.

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) has emerged as a viable treatment for isolated medial or lateral knee osteoarthritis, demonstrating improved implant survival rates over time despite its early challenges since its inception in 1950. Advancements in design and instrumentation have contributed significantly to the enhanced longevity of UKA implants[1,2]. Notably, clinical complications associated with UKA are lower compared to total knee arthroplasty (TKA), although procedure-related complications remain a concern[3]. Examining the implant survival rates reveals a disparity between TKA and UKA. The Australian Orthopaedic Association's National Joint Replacement Registry reported 10-year survival rates of 94.4% for TKA and 84.7% for UKA in primary osteoarthritis cases. Similar trends were observed in the National Joint Registry of England and Wales and the Swedish Knee Arthroplasty[4,5].

Zhao et al's study[6], titled "Analysis of the causes of primary revision after unicompartmental knee arthroplasty: A case series" offers a comprehensive analysis of UKA revision indications at the Department of Orthopedics of Guangdong Provincial Hospital of Traditional Chinese Medicine from November 2016 to December 2020. The study provides a detailed, case-by-case analysis of the factors leading to knee revision surgery in 13 patients, distinguishing between those who required reoperation due to intraoperative technical failures and those whose failures stemmed from postoperative outcomes. Three cases were attributed to surgical errors (1 free body and 2 arthrotomy dehiscences). Ten other cases were analyzed, with highlights including 1 posterior ACL rupture after surgery leading to instability, 1 patient with rheumatoid arthritis, 3 bearing dislocations in mobile-plate UKAs, 2 tibial loosenings, 2 progressions of osteoarthritis with remaining osteophytosis, and 1 case of medial collateral ligament instability.

COMPLICATIONS FOLLOWING UNICOMPARTMENTAL KNEE ARTHROPLASTY

When analyzing the complications of UKAs, it is crucial to consider the surgeon's surgical volume and experience, as revision rates decrease significantly when more than 30 surgeries are performed per year[7]. Aseptic loosening is the most common cause of early UKA failure, with reports ranging from 25%-55%[2,8,9]. The complexity of the revision is influenced by the nature of the failure, with generally poorer functional scores and higher revision rates observed in UKA revisions compared to primary TKA[10,11]. In this series, two cases experienced aseptic loosening. Both cases had a fixed tray implanted, and the revision was converted to a TKA. Proper final positioning of the components is crucial for success and implant survival during these surgeries. It would be appropriate for the authors to analyze the implant positioning in the postoperative X-rays to evaluate possible associations between positioning and failures. Significant decreases greater than 2 mm in the medial space compared to the lateral space have been linked to tibial loosening[12]. Designs with mobile plates that result in greater varus or valgus postoperatively, increased medial articular line height, altered posterior slope, or internal tibial rotation have been associated with bearing dislocations in mobile plate designs[13]. In this series, bearing dislocations in mobile plate designs were the most common reason for revisions, accounting for 3 cases. Two of these cases were successfully resolved with liner changes, while the remaining case necessitated conversion to TKA.

The authors did not mention the use of navigation assistance, patient-specific instruments, or robotic assistance. Numerous studies have demonstrated that computer-assisted navigation can decrease early failures, with Chowdhry et al[14] reporting a survival rate exceeding 97.5% after 5 years[14,15]. The increasing use of robot-assisted surgery in UKA allows for precise planning and execution of operative goals, potentially improving component positioning and overall outcomes. However, debates regarding its efficacy and cost-effectiveness persist, raising questions about its long-term impact on UKA survival rates[16,17].

CONCLUSION

The article by Zhao et al[6] not only elucidates the complexities of UKA revisions but also underscores the importance of continuous improvement in surgical techniques and the adoption of innovative technologies. As the demand for joint arthroplasty procedures rises with aging populations, ensuring implant longevity, functional enhancement, and patient satisfaction becomes paramount. This study emphasizes the significance of meticulous preoperative assessment, precise implant positioning, and ongoing education for healthcare providers to mitigate risks and improve outcomes. By embracing advancements such as robot-assisted surgery and refining surgical approaches, healthcare professionals can improve the success rates of UKA and other joint arthroplasty procedures. Moreover, promoting a proactive, data-driven mindset within healthcare systems can lead to better patient outcomes, improved patient experiences, and enhanced health equity. In conclusion, this work serves as a catalyst for ongoing discussion, critical thinking, and further advancements in the field.