Total Knee Arthroplasty Outcome for 129 Knees 80 Years and Older in Chinese Population

Background Methods


Introduction
Total knee arthroplasty (TKA) is a successful operation to alleviate pain and improve function for patients with advanced arthritis of the knee [1]. The safety of TKA has been improved based on the recent advances in anesthesia, perioperative health care, and surgical techniques, especially for older patients [2]. Moreover, most of the literature on patients 80 years of age and older was published in relation to Western populations. Knee anatomy and exercise habits of the Chinese population are different from Caucasians, with a relatively smaller bone structure and less exercise in the elderly. On the basis of one of the hospitals with the largest number of TKA patients over 80 years old in China, the current study was done to assess the reliability, durability, and satisfaction of TKA in Chinese patients 80 years of age or older with particular attention to perioperative operative time, intraoperative blood loss, knee function, patients' satisfaction, medical morbidity, mortality, and rate of complications [3], [4], [5].
We asked whether elderly patients over 80 could bene t from TKA, and whether the life span of the patients will be affected after bilateral TKA.

Study design
Between February 2009 and December 2017, 117 patients (152 knees) received TKA due to osteoarthritis with 80 years of age and older. These TKAs were performed by a senior operator and 98 patients (129 knees) met the inclusion criteria (mean 82 years; range, 80-90 years) (Fig. 1). The patients' mean weight was 68 kg (range, 43-97 kg). The indications for surgery were advanced, symptomatic arthritis of the knee. All patients had a pre-anesthetic medical evaluation by a medical specialist. Sixty-four arthroplasties were done on the left knee. There were 60 women and 38 men, and 8 patients had simultaneous bilateral TKAs under one anesthesia. Sixty-seven patients had a unilateral TKA and 23 patients had staged bilateral TKAs including 6 staged bilateral TKAs during one hospital stay. The preoperative data included patient demographics ( Table 1).
The inclusion criteria were as follows: 1) aged 80 years and older; 2) all surgical procedures were conducted by the same surgeon; 3) the indications for surgery were advanced, symptomatic arthritis of the knee; and 4) a minimum follow-up period of 3 years. The exclusion criteria were as follows: 1) a history of rheumatoid or ankylosing spondylitis; 2) any medical disability that limited the ability to walk and would not be considered suitable for a minimum 3-year follow-up period; 3) disabling diseases involving other joints of the lower extremities, and severe deformities (varus angulation, valgus angulation, or exion contracture of more than 15°); 4) mental diseases; 5) patients participating in other trials were excluded; and 6) Patients lost to follow-up.
The data of the operative data included the operation time, intraoperative blood loss and transfusion, tourniquet time, ASA (American Society of Anesthesiologists Physical Status Classes), prosthesis type, patella replacement and complication (Table 2). Preoperative and postoperative clinical evaluations were performed by two independent orthopedic surgeons according to KSS, VAS, ROM, FJS, Crutch (Table 3,4) and radiographic data [6]. The death causes of patients after TKA were shown in Table 5. Data regarding the intraoperative and immediate postoperative complications were noted immediately. Revision for any reason was documented. Data results are cross-checked by the other two independent orthopedic surgeons.
Patients' satisfaction is classi ed as Very good if they have no other uncomfortable feelings; Good if they have few special feelings; General if they could accept some uncomfortable feelings; Not good if they could not accept the uncomfortable feelings [7].
All medical records were approved by patients. All participants signed informed consent, and the study was approved by the clinical research Ethics Committee of Chinese PLA General Hospital, Beijing, China.
All methods were performed in accordance with the relevant guidelines and regulations.

Operation procedures
All patients received TKA (Depuy PFC, Depuy RPF, Gemini CR). The surgeries were performed by one senior physician under tourniquet control using a medial parapatellar approach[8]. Twenty-six patellar resurfacing was applied for 13 left and 13 right knees [7]. We commonly aim to accurately reproduce the preoperative thickness of the patella, as measured by callipers after osteotomy of the tibia and femur. When resurfacing was not performed, the patella should be repaired by removing the osteophytes and smoothing the brillated cartilage. Patellofemoral tracking was assessed by the "no thumb test" after inserting the implants.
All patients were managed with the same perioperative regimen [5]. Patients received antibiotic prophylaxis with intravenous Ceftriaxone Sodium (2g, 30 minutes before the operation followed by 2g for the next day). If the operation time exceeds 3 hours or the blood loss is greater than 1500ml, a second dose could be given during the operation. The postoperative regimen included: intravenous and oral analgesia (oral until 6 weeks after TKA), prophylaxis against venous thrombosis and knee extension training immediately. Progressive resistance exercises, gravity-assisted regaining of exion and walking with support were started on the rst day after TKA [5]. All patients used walkers for 6 weeks postoperatively and were taught by the same experienced rehabilitation doctor.
Statistical analysis SPSS 24.0 (SPSS Inc) was used for statistical analysis by an independent orthopedic surgeon. Clinical data was described using means ± standard deviations. The level of statistical signi cance was de ned as p < 0.05. Paired t-tests were performed to determine the difference in ROM, KSS, and VAS between before and after TKA. Chi-square test or Fisher exact test were performed to determine the difference in FJS, Crutch and Satisfaction. The Kaplan-Meier was used for survival analysis.

Results
There were no elderly patients over 80 years of age in our hospital who underwent revision surgery after TKA ( Table 1). The patients were followed up until death or for a minimum of 3 years (range, 3-11 years). The preoperative hemoglobin of patients with bilateral TKAs in one stage was not statistically signi cant than that of patients with one knee in one stage, 127.50 ± 9.67 g/L and 125.65 ± 15.33 g/L respectively (p > 0.05) ( Table 1). One patient died after a pulmonary embolism on postoperative Day 6.
One patient was transferred to Intensive Care Unit after the operation due to intraoperative hypovolemia. One patient had an allergic reaction to blood transfusion during the operation. There was one patient with two stiff knees at 0°after primary TKA ( Table 1). The imaging results of all review patients are normal.
The surgical time of patients with two knees in one stage was signi cantly longer than that of patients with one knee in one stage, 167.63 ± 67.62 min and 112.26 ± 27.03 min respectively (p < 0.05). The blood transfusion of patients with two knees in one stage was signi cantly higher than that of patients with one knee in one stage (1478.75 ± 912.57 mL and 772.56 ± 375.66 mL respectively) (p < 0.05). And the blood loss between the two groups was not statistically signi cant (350.00 ± 141.42 and 225.04 ± 152.10, respectively) (p > 0.05). The tourniquet mean time was 61.32 ± 20.80min. The distribution of ASA, prosthesis, patella replacement and surgical complication was not statistically signi cant (p > 0.05) ( Table 2).
The proportion of FJS 50 points or more was 85%. We observed no difference between two genders in FJS at year 3 (p > 0.05) ( Table 4). The proportion of patients who did not use crutches at last follow-up was 52% (p > 0.05) ( Table 4). Other patients with crutches or wheelchairs after TKA mainly complained of lower limb weakness. The patients' satisfaction rate was 94% (p > 0.05) ( Table 4).
Of the 24 patients who died after TKA, 15 met the minimum three-year follow-up time requirement. The death causes of patients after TKA were shown in Table 5. Heart failure and cancer were most common.
The survival proportions between bilateral and unilateral TKAs were not statistically signi cant in 80 years and older patients (p > 0.05) (Fig. 2,3).

Discussion
A growing subset of patients had a TKA with greater life expectancy after reaching age 80 [9]. This study was done to address the TKA outcome, the rate of complication, patients' satisfaction, and mortality after primary TKA in patients age 80 years and older.
The 80 years and older patients frequently had several preoperative medical comorbidities. A history of hypertension and cardiac disease was most common. Belmar et al1 showed that postoperative medical complications often could be linked with preoperative medical conditions. A high rate of complications had been reported in several series of primary and revision TKA in elderly patients [10], [11], [12]. Hosick et al [13] reported that a large number of comorbid conditions were present in patients older than 80 years who had a TKA. In that study, the rate of postoperative medical complications was 7%. In each of these studies, the medical complications were typically transient and rarely compromised the ultimate outcome of the TKA. Then preoperative detailed information obtained from patients and their family members about medical history as well as optimal perioperative patient care is required [14], [15]. However, we could not link the postoperative medical complications to the preoperative medical comorbidities. In our study, the rate of postoperative medical complications was 5%. The preoperative hemoglobin of patients between bilateral TKAs in one stage and unilateral TKAs were not statistic signi cant (p > 0.05), which showed that the preoperative hemoglobin was not the most important factor in deciding bilateral TKAs in one stage [16].
In the present study, the period of bilateral TKAs hospital stay (23.07 ± 9.20) was longer than the young bilateral TKAs patients [11]. In China, the postoperative self-physical therapy of old adult patients is usually continued until the patients' ability to walk becomes steady. The delayed postoperative rehabilitation schedule in old adult patients is due to their decreased physical strength and cognitive function.
The KSS clinical and functional scores improved signi cantly for patients 80 years of age and older from preoperative mean scores of 33 and 27 to latest follow-up scores of 87 and 51 respectively (p < 0.05). No knees have required revision subsequently. The VAS improved signi cantly from preoperative mean scores of 8 to latest follow-up scores of 0 (p < 0.05). At least a follow-up time of 3 years after surgery, all but one patient had substantial relief of pain after TKA. The data were similar to studies which were reported by several authors showing that TKA provides predictable relief of pain and improvement in function in the octogenarian populations [17].
However, the ROM did not improve signi cantly from preoperative mean 89°to latest follow-up 93°(p > 0.05). They bene ted mainly from pain relief and function improvement after TKA, but limited from squatting and other large knee exion activities. To sit in a chair without using one's hands requires 93°k nee exion on average, and tying one's shoes while seated requires 106° exion on average. Most elderly patients said that their knee function after TKA was adequate for daily life and could ensure basic selfcare [18].
The proportion of patients who did not use crutches at last follow-up was 52%. Other patients with crutch or wheelchair after TKA mainly complained of lower limb weakness. The exercise of muscle strength of the lower limbs of elderly patients over 80 years was very important for postoperative recovery, and it was also di cult among Chinese population to keep at home [19].
The proportion of patients' satisfaction rate was 94%, and the 50 points or more rate of "Forgotten Joint" Scale (FJS) was 85%. This result indicated that "relieving the pain and keeping basic functions" the main purpose of TKA was achieved [20], [21].
Our study has several limitations. The primary limitation is that the study lacked adequate power to compare the results of TKAs with two knees in one stage with two knees in two stages. The other limitation is that several prostheses were used during the study, and comparison of results based on the implant used also would be prone to inadequate power. Third, the minimum 3-year follow-up period is still short, which may have impacted the results. We will continue to follow up the patients for 5 to 15 years, as the patients are currently aged above 80.

Conclusion
TKA was reliable, durable, and satis ed in patients older than 80 years in Chinese population. We recommend TKA for patients 80 years of age and older based on the surgical indications. Abbreviations TKA, total knee arthroplasty; KSS, knee society score; BMI, body mass index; ROM, range of motion; VAS, visual analogue scale; FJS, "Forgotten Joint" scale; ASA, American Society of Anesthesiologists Physical Status Classes.

Declarations
Funding None.

Con ict of interest
Each author certi es that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a con ict of interest in connection with the submitted article.

Competing interests
The authors declare that they have no competing interests.

Availability of data and materials
We do not wish to share our data, because some of the patient's data regarding individual privacy, and according to the policy of our hospital, the data could not be shared with others without permission.
Code availability Not applicable.

Ethics approval and consent to participate
All medical records were approved by patients. All participants signed informed consent, and the study was approved by the clinical research Ethics Committee of Chinese PLA General Hospital, Beijing, China.

Consent for publication
Not applicable.