This study found that patients with more preoperative concomitant diseases were more likely to develop hypoalbuminemia. According to the results of this study, the proportion of patients with cardiovascular disease, diabetes mellitus, bedsore, abnormal liver and kidney function, or more than 2 concomitant diseases before operation was higher in the case group (P < 0.05). Hypertension is one of the most common cardiovascular diseases in the world. It has been found that the pathogenesis of hypertension is closely related to the damage of vascular endothelial function. Microvascular permeability is increased in patients with hypertension. When complicated with trauma or surgery, a large number of inflammatory cytokines releases, which aggravates the injury of capillary endothelial cells, causes vascular leakage, results in hypoalbuminemia. In patients with diabetes, their insulin receptor is inhibited under stress, the oxidative metabolism of glucose is abnormal, and the negative nitrogen balance is more stubborn and obvious. Abnormal liver and kidney function will reduce its protein synthesis ability and plasma protein synthesis, such as hypoproteinemia caused by cirrhosis.
Patients with hypoalbuminemia were more likely to have postoperative complications. Compared with the control group, patients with hypoalbuminemia had a higher incidence of postoperative complications, especially delayed wound healing, pleural effusion and pneumonia. And there was no significant difference in deep venous thrombosis, dyspepsia, constipation and electrolyte disturbance of lower extremities. Meanwhile, we used binary logistic regression analysis to analyze the correlation between sex, age, BMI, fracture and preoperative albumin level, the result showed that the risk of postoperative complications increased by 6.9% with every 1 year old increasing (age > 60), and the risk of postoperative complications in patients with preoperative hypoalbuminemia (serum albumin < 35g/L) was 1.89 times higher than that in patients with normal preoperative albumin (preoperative serum albumin ≥ 35g/L).
In this study, there was one dead patient who was admitted to our hospital for surgical treatment because of femoral neck fracture. The patient had a history of hypertension and after hysterectomy for endometrial carcinoma. The causes of death were acute renal failure, acute cerebral infarction and metabolic acidosis. Although the patient had hypoalbuminemia before operation, the main cause of death was preoperative abnormal liver and kidney function and basic physical condition, rather than preoperative hypoalbuminemia.
In addition, we found that intraoperative blood loss cannot be used to predict albumin loss seperately. The results showed that the amount of postoperative albumin loss in the case group was significantly lower than that in the control group, no matter in the patients who received THA or HHA (P < 0.05), but there was no significant difference in operation time and intraoperative blood loss between the two groups (P > 0.05). It is suggested that intraoperative blood loss is not the only cause of postoperative albumin loss, but also related to vascular permeability or abnormal albumin metabolism.
As for the changes of serum albumin during the perioperative period, the results of this study showed that the serum albumin levels of THA case group before operation, 1 day and 3 days after operation was lower than those of the THA control group (P < 0.05), but there was no significant difference on the 7 day after operation (P > 0.05). And the albumin level in the HHA case group was lower than that in the HHA control group before operation and 1 day after operation, but there was no significant difference between 3 days and 7 days after operation (P > 0.05). All patients in this study were given exogenous albumin supplementation if their serum albumin was less than 30g / L at 3 days after operation. This may be one of the main reasons why there is no significant difference in albumin level between the two groups 7 days after operation.
Compared With Previous Studies
The results of this study are consistent with other findings that have a higher incidence of complications in malnourished patients receiving THA. However, most studies only regard preoperative hypoalbuminemia as one of the influencing factors, and do not deeply study the relationship between preoperative hypoalbuminemia and postoperative complications of THA. At the same time, other studies are different from the results of this study in some aspects. Newman et al.  found that compared with the control group, hypoalbuminemia patients had an 80% higher risk of any complications, a 113% higher risk of major complications (such as pulmonary embolism, acute renal failure, myocardial infarction, etc.), and a 79% increased risk of minor complications (such as wound infection, blood transfusion, lower extremity deep venous thrombosis, etc.), and a 97% increase in reoperation risk. The high incidence of postoperative complications were different in our study. This may be related to factors such as the ratio of fracture patients and the different preoperative concomitant diseases in the two samples.
In addition, preoperative hypoalbuminemia also affects the incidence of complications after other joint replacements. Blevins et al.  found that preoperative hypoalbuminemia was a high risk factor for PJI and showed good sensitivity and specificity in predicting PJI. Kamath et al.  evaluated patients treated with TKA and found that patients with hypoalbuminemia had higher incidences of deep surgical site infection, pneumonia, urinary tract infection and sepsis than those with normal albumin levels. Patients with hypoalbuminemia had a higher risk of death and coma than patients with hypoalbuminemia who required unplanned tracheal intubation, intraoperative or postoperative blood transfusion, retention of ventilator for more than 48 hours, and coma. Any complications and infections (systemic and traumatic) are also more common. However, in our study, although there was one death in preoperative hypoalbuminemia, the cause of death was mainly due to poor basic conditions and abnormal liver and kidney function, rather than hypoalbuminemia. These studies have shown that preoperative hypoalbuminemia can significantly affect the incidence of complications after joint replacement.