Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty, particularly for low volume surgeons. The recent introduction of robotic-arm assisted systems has allowed for increased accuracy, however new systems typically have learning curves. The objective of this study was to determine the learning curve of a robotic-arm assisted system for UKA.

Methods A total of 152 consecutive robotic-arm assisted primary medial UKA were performed by five surgeons between 2017 and 2021. Operative times, implant positioning, reoperations and patient-reported outcome measures (PROMS; Oxford Knee Score, EuroQol-5D, and Forgotten Joint Score) were recorded.

There was a learning curve of 11 cases with the system that was associated with increased operative time (13 minutes, p<0.01) and improved insert sizing over time (p=0.03). There was no difference in implant survival (98.2%) between learning and proficiency phases (p = 0.15), and no difference in survivorship between ‘high’ and ‘low’ usage surgeons (p = 0.23) at 36 months. There were no differences in PROMS related to the learning curve. This suggested that the learning curve did not lead to early adverse effects in this patient cohort.

The introduction of a robotic-arm assisted UKA system led to learning curves for operative time and implant sizing, but there was no effect on patient outcomes at early follow- up. The short learning curve was independent of UKA usage and indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons.

The primary aim was to assess the reliability of ultrasound in the assessment of humeral shaft fracture healing. The secondary aim was to estimate the accuracy of ultrasound assessment in predicting humeral shaft nonunion.

Twelve patients (mean age 54yrs [20–81], 58% [n=7/12] female) with a non-operatively managed humeral diaphyseal fracture were prospectively recruited and underwent ultrasound scanning at six and 12wks post-injury. Scans were reviewed by seven blinded observers to evaluate the presence of sonographic callus. Intra- and inter-observer reliability were determined using the weighted kappa and intraclass correlation coefficient (ICC). Accuracy of ultrasound assessment in nonunion prediction was estimated by comparing scans for patients that united (n=10/12) with those that developed a nonunion (n=2/12).

At both six and 12wks, sonographic callus was present in 11 patients (10 united, one developed a nonunion) and sonographic bridging callus (SBC) was present in seven patients (all united). Ultrasound assessment demonstrated substantial intra- (6wk kappa 0.75, 95% CI 0.47-1.03; 12wk kappa 0.75, 95% CI 0.46-1.04) and inter-observer reliability (6wk ICC 0.60, 95% CI 0.38-0.83; 12wk ICC 0.76, 95% CI 0.58-0.91). Absence of sonographic callus demonstrated a sensitivity of 50%, specificity 100%, positive predictive value (PPV) 100% and negative predictive value (NPV) 91% in nonunion prediction (accuracy 92%). Absence of SBC demonstrated a sensitivity of 100%, specificity 70%, PPV 40% and NPV 100% (accuracy 75%). Of three patients at risk of nonunion based on reduced radiographic callus formation (Radiographic Union Score for HUmeral fractures <8), one had SBC on 6wk ultrasound (and united) and the other two had non-bridging or absent sonographic callus (both developed a nonunion).

Ultrasound assessment of humeral shaft fracture healing was reliable and predictive of nonunion, and may be a useful tool in defining the risk of nonunion among patients with reduced radiographic callus formation.

Cardiovascular disease is now the leading cause of morbidity and mortality worldwide. Raised blood pressures (BP) are associated with increased cardiovascular risks such as myocardial infarction, stroke and arteriosclerosis. During surgery the haemodynamic effects of stress are closely monitored and stabilised by the anaesthetist. Although there have been many studies assessing the effects of intraoperative stress on the patient, little is known about the impact on the surgeon.

A prospective cohort study was carried out using an ambulatory blood pressure monitor to measure the BP and heart rates (HR) of three consultants and their respective trainees during hallux valgus, hip and knee arthroplasty surgery. Our principle aim was to assess the physiological effects of performing routine operations on the surgeon. We noted if there were any differences in the stress response of the lead surgeon, in comparison to when the same individual was assisting. In addition, we recorded the trainee's BP and HR when they were operating independently. The intraoperative measurements were compared with their baseline readings and their stress response, assessed using the Bruce protocol.

Many trends were noted in this pilot study. All of the surgeons had higher BP and HR readings on operating days compared to baseline. The physiological parameters normalised by one hour post-theatre list in all subjects. When the trainer was leading the operation, their BP gradually increased until implant placement, while their trainees remained stable. On the other hand, when the trainee was operating and the trainer assisting, the trainer's BP peaked at the beginning of the procedure, and slowly declined as it progressed. The trainee's BP remained elevated throughout. The highest peaks for trainees were noted during independent operating.

We conclude that all surgery is stressful, and that trainees are more likely to be killing themselves than their trainers.