Surgical mortality is a rare occurrence in elective orthopaedic practice [7, 13, 14]. However, there are a number of papers which indicate such an association in elective total knee replacement. It is suggested that the higher the volume the lower the risk of mortality [7, 8, 15–17]. Interestingly, there is no difference between highly specialized centers and non-specialized hospitals. In one study, it has been shown that there is no relation between surgeon volume and surgical mortality [18].

The lowest complications rates (and consequently the lowest morbidity rates) occur amongst surgeons in the highest volume groups. Low volume surgeons (<52 patients/year) had higher transfusion rates due to postoperative anemia and higher occurrence of postoperative infection [19, 20]. When surgeon volume increased above 200 TKR a year, it was also associated with a decreased risk of myocardial infarction (MI), pulmonary embolus (PE), deep surgical site infection and in some cases, mortality [21–27]. A 5 year meta-analysis study reviewing over 200,000 TKRs concluded that lower volume hospitals were associated with an increased rate of PE [18]. It was reported that there is a decreased risk of respiratory complications when a surgeon performs a minimum of 50 TKRs a year [7, 8]. The incidence of hemorrhage (upper G.I. or other) was significantly higher in high volume and specialized centers, probably due to more intensive use of pharmacologic thromboembolism prophylaxis [13, 14, 28]. A statistically significant decrease in transfusion rate following TKA performed by HV surgeons compared to LV surgeons (4 % vs 13 %) was also reported [19]. A statistically significant association between low surgeon volume and infection rates either in hospital (almost twice as high) [26], or 1 year postoperatively (almost 2.5 times higher rate) [22], has been suggested. Neither study specified whether this was deep or superficial site infection. A statistically significant decrease in pneumonia rates following TKA performed by HV surgeons (1.02 % HV vs 1.68 % LV) is reported by some authors [7, 8]. Finally, a significant increase in TKA operation time for LV surgeons (165 min vs 135 min) should be considered as an aggravating factor due the increase of intraoperative risks [24]. Regarding hospitalization, significantly higher lengths of stay (LOS) were observed in low volume units and surgeons (mean of 5 days in HV as opposed to 7 days in LV centers and surgeons), with no influence on outcome, however [10, 20, 21, 29, 30].

It must be stated that modern, less invasive operating techniques (MIS/Mini-Sub/Midvastus exposure) as well as computerized/robotic assisted placement of the components (that usually require advanced surgeon training and skill) mainly affect the immediate postoperative co-morbidity factors (less soft tissue damage and blood loss, reduced need for analgesia, earlier patient mobilization etc.) and “technical” details (improved radiographic component alignment leading to correct mechanical axis and prosthesis function) [31–33]. Recent literature suggests that the long-term clinical outcome remains uninfluenced by such procedures.

For TKR, crude analysis shows no relationship between surgeon and hospital volume and readmission rate to hospital within a year. However, there is good evidence that the rate of readmission was reduced in Training Centers [18]. There is evidence of a higher risk of revision surgery within 6 months in HV Hospitals, although this finding is possibly due to the fact that highly specialized centers tend to take up more complex patient cases which often require reoperation. Patients operated on by low-volume surgeons in low-volume hospitals presented lower WOMAC functional status scores at 2 year follow up (<60 on a scale of 0–100) when compared to patients operated on by higher volume surgeons or/and in higher volume hospitals [7, 8]. Other studies have also demonstrated that higher surgical and hospital volumes result in more favorable patient outcomes [7, 34, 35]. Patients operated on by LV surgeons were more likely to report an inability to flex the knee to 90°, and more likely to report an inability to achieve full extension at 2 year follow up [8]. It is suggested that surgeon volume is a greater predictor of favorable outcome than hospital volume, but there is also evidence that both surgeon and hospital volume influence outcome. It seems that TKA mid-term survival does not depend on surgeon volume [26]. Moreover, no association between surgeon volume and 3 year and 1 year revision rate, respectively, has been observed [21, 30].

Findings with regard to TKA costs warrant a brief mention. In particular, TKA costs were markedly higher in low volume non-specialized hospitals than in high volume Units and Centers of Excellence, probably due to the difference in LOS and a higher incidence of adverse effect at the former. It was also found that academic medical centers typically have higher costs when compared with other hospitals [16, 17, 36]. However, at least some of the higher costs that have been observed in teaching hospitals seem to be related to the greater complexity of patient populations served by these hospitals [37].