2.1 Study population

The inclusion criteria for the study were patients diagnosed with primary knee osteoarthritis who were scheduled for elective total knee arthroplasty between January to April 2020 at a tertiary hospital but had their surgery postponed by 6 months. All 160 patients were included into the study and there none were lost to follow up. The average age of the study cohort was 68 years old, while the average BMI was 27.2 kg/m² (initial preoperative assessment) and 27.4 kg/m² (second preoperative assessment) respectively. Out of the 160 patients, 107 were female, 53 were male (Table 1). There were no complex primary total knees planned within the cohort (i.e. none with implant removal, augmentation or increased constraints). Whilst awaiting for their total knee surgery, they were routinely referred to physiotherapy for muscle strengthening as well familiarization with postoperative exercises.

2.2 Patient-reported clinical outcome and quality of life measures

Assessment was performed by an independent healthcare professional during their preoperative assessments. There were two preoperative assessments conducted, the first was a month prior to the initial planned operative date, and the second was a month prior to the postponed operative date (6 months later). Quantifiers of functional outcomes used were the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS)⁵ and Oxford Knee Score (OKS).⁶

Both KSFS and KSKS are scored out of 100 points, with 100 being the best score. KSKS takes into account their pain score, alignment, range of motion and stability whereas KSFS assesses the patient's general functionality. OKS is comprised of 12 questions, scoring 1–5 points per question. It produces a score between 12 and 60, with 12 being the best outcome.

Short Form-36 (SF-36) was used to assess the impact of the delays on the patient's quality of life.⁷ The SF-36 form has 2 categories with 4 domains each. Physical category includes domains such as Physical Functioning, Social Functioning, Role-Physical and Bodily Pain. The mental category included domains such as Mental Health, Role-Emotional, Vitality and General Health. The authors converted the domains of the SF-36 into two summary scores; the Physical Component Score (PCS) and Mental Component Score (MCS). This was to allow a narrower confidence interval and the elimination of both floor and ceiling effects.⁸

Minimal clinically important difference (MCID) is the minimum change of an outcome score that an individual would perceive to be significant. The MCID for, KSFS, KSKS, OKS and SF-36 PCS was taken to be 6.1, 5.3, 5.0 and 10.0 respectively^9,10

5.1 Delaying total knee arthroplasties

A review of the current literature only found one study which has investigated the development of patients’ clinical symptoms while they await their postponed knee arthroplasty surgery during the COVID-19 period. Endstrasser et al.¹⁴ reviewed 24 patients with delayed TKA and 39 with delayed total hip arthroplasties (THA) and found that their mean Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores deteriorated significantly while the SF-12 PCS decreased significantly during the lockdown period (within 2 months). However, one limitation identified was the potential systemic bias as the patients were surveyed via telephone and may have hoped for earlier surgical appointments if they reported higher pain scores. On the contrary, the patients from this study were interviewed a month before their scheduled operation dates, as part of the routine preoperative checks. Hence, they were less likely to falsify higher pain scores to get earlier scheduled dates as their responses will not affect their operative dates.

Prior to 2020, there have been a number of studies which reported on preoperative clinical scores in patients suffering from knee osteoarthritis awaiting total knee arthroplasty, but the findings were conflicting. Kapstad et al.¹⁵ reported that increased waiting time for TKA was associated with deterioration of preoperative WOMAC stiffness and total scales. Ackerman et al.¹⁶ reported an overall deterioration in the preoperative Health-Related Quality of Life (HRQoL) in patients who waited for ≥6 months for their joint replacement surgeries. Additionally, Scott et al.¹⁷ reported that 263 TKA patients (12%) out of 2168 were in a health state ‘worse than death’ according to the EuroQol 5-dimension questionnaire while awaiting TKA with a mean op waiting time of 23.1 weeks. However, there were also studies that concluded that the length of waiting time for TKA did not significantly affect the clinical outcomes or quality of life reported by patients.^18–20

Regarding postoperative outcomes, Lizaur-Utrilla et al.²¹ concluded that waiting time of >6 months for TKA negatively influenced 1-year postoperative satisfaction and clinical outcomes (SF-12, WOMAC and Knee Society Scores). Hence, postponement of elective TKAs during this pandemic may produce detrimental effects in postoperative outcomes and scores.

5.2 A pandemic's effect on orthopaedics' patients

During the COVID-19 pandemic, patients’ access to alternative treatment such as physiotherapy services were limited and most had minimal physical activities due to restrictions imposed as part of the measures to reduce virus transmission.^22,23 The authors hypothesize that these factors might have resulted in increased pain and worsening of clinical outcomes in the patients during the COVID-19 lockdown period.

It is well known in the literature that osteoarthritis is the leading cause of pain and disability in many countries and carries a large disability burden.²⁴ This study also demonstrated the worsening clinical outcomes and quality of life of patients who had their TKA postponed for 6 months. However interestingly, a study conducted by Wilson et al.²⁵ showed that out of 111 patients surveyed, 45% of them reported a desire to delay their TKA operations and wait longer until the COVID-19 pandemic subsides instead of getting their surgeries once operations resume. It is unsure whether this particular group of patients is suffering from worsening physical pain, but it helps to serve as a reminder that some patients are willing to bear with the prolonged physical disability from end-stage knee osteoarthritis until the pandemic subsides.

5.3 Addressing the surgical backlog

In the past few decades, the world has seen a surge in demand for TKA. With an ageing population, the annual number of TKA cases is projected to rise even further in the next few decades.²⁶ The average waiting period for TKA varies between countries and healthcare institutions, but a study conducted in United States (US) estimated the waiting time for TKA was around 7 months,²⁷ while the average waiting time from first consult to TKA was around 25 months. Unfortunately, the COVID-19 pandemic has exacerbated this demand supply mismatch. It has been estimated that approximately 30,000 primary hip and knee arthroplasty procedures was cancelled each week in the US while COVID-19 restrictions regarding nonessential surgery are in place.²⁸ Even in the best case scenario, there will be a total backlog of more than a million surgical cases after 2 years of delaying elective orthopaedic surgeries.²⁹

With countries adopting an endemic approach of living with COVID-19,³⁰ there is a pressing need to address the backlog of elective surgical cases whilst reducing hospital resource consumption to avoid competing for healthcare resources used to manage COVID-19. Available solutions that can streamline our elective orthopaedic surgeries include outpatient or day surgery TKA^31,32 to avoid occupying hospital beds as well as unnecessary nursing requirement. The use of telemedicine for consultations can increase physicians capacity of reviewing patients and improve healthcare efficiency. It also improves patient's access to healthcare which would allow them to receive timely treatment.^33,34 Prioritization of urgency of elective TKAs may also help play a large part in clinical outcomes of patients awaiting TKAs.³⁵

5.4 Limitations

This study is not without its limitations. The findings from this study might not be generalizable, as some countries might delay TKA surgeries longer or shorter than 6 months due to different COVID-19 guidelines employed by governing bodies. Also, whilst this study shows that delay in TKA does have detrimental effects on patient's quality of life preoperatively, the mean difference in OKS, KSKS and SF-36 PCS did not meet its MCID. Furthermore, it is unable to evaluate if there are any permanent long term effects as it does not include postoperative outcomes.