Postoperative surgical site infection in patients treated with lumbosacral fusion has been believed to be caused by perioperative contamination (Perioperative Inside-Out infections) in patients with comorbidities. With the proximity of these incisions to the perianal region and limited patient mobility in the early post-operative period, local contamination from gastrointestinal and/or urogenital flora (Postoperative Outside-In infections) should be considered as a major source of complication.

A single center, retrospective review of adult patients treated with open posterior lumbosacral fusions between January 2014 and January 2021. We aimed to identify common factors in patients experiencing deep postoperative infections. Oncological, minimally invasive, primary infection, and index procedures carried out at other institutions were excluded.

We identified 489 eligible patients, 20 of which required debridement deep to the fascia (4.1%). Mean age (62.9 vs 60.8), operative time (420 vs 390 minutes), estimated blood loss (1772 vs 1790 mL) and median levels fused (8.5 vs 9) were similar between the infected and non-infected groups. There was a higher percentage of deformity patients (75% vs 29%) and increased BMI (32.7 vs 28.4) in the infected group. The mean time from primary procedure to debridement was 40.8 days. Four patients showed no growth on culture. Three showed Staphylococcus species (Perioperative Inside-Out infections) requiring debridement at a mean of 100.3 days (95%CI 0- 225 days). Thirteen patients showed infection with intestinal or urogenital pathogens (Postoperative Outside-In infections) requiring debridement at a mean of 20.0 days (95%CI 9-31 days). Postoperative Outside-In infections led to debridement 80.3 days earlier than Perioperative Inside-Out infections (p= 0.007).

In this series, 65% of deep infections were due to early local contamination by gastrointestinal and/or urogenital tracts pathogens. These infections were debrided significantly earlier than the Staphylococcus species infections. Due to the proximity of the incisions to the perianal region, there should be increased focus on post-operative local wound management to ensure these pathogens are away from the wound during the critical stages of wound healing.

Single level discectomy (SLD) is one of the most commonly performed spinal surgery procedures. Two key drivers of their cost-of-care are duration of surgery (DOS) and postoperative length of stay (LOS). Therefore, the ability to preoperatively predict SLD DOS and LOS has substantial implications for both hospital and healthcare system finances, scheduling and resource allocation. As such, the goal of this study was to predict DOS and LOS for SLD using machine learning models (MLMs) constructed on preoperative factors using a large North American database.

The American College of Surgeons (ACS) National Surgical and Quality Improvement (NSQIP) database was queried for SLD procedures from 2014-2019. The dataset was split in a 60/20/20 ratio of training/validation/testing based on year. Various MLMs (traditional regression models, tree-based models, and multilayer perceptron neural networks) were used and evaluated according to 1) mean squared error (MSE), 2) buffer accuracy (the number of times the predicted target was within a predesignated buffer), and 3) classification accuracy (the number of times the correct class was predicted by the models). To ensure real world applicability, the results of the models were compared to a mean regressor model.

A total of 11,525 patients were included in this study. During validation, the neural network model (NNM) had the best MSEs for DOS (0.99) and LOS (0.67). During testing, the NNM had the best MSEs for DOS (0.89) and LOS (0.65). The NNM yielded the best 30-minute buffer accuracy for DOS (70.9%) and ≤120 min, >120 min classification accuracy (86.8%). The NNM had the best 1-day buffer accuracy for LOS (84.5%) and ≤2 days, >2 days classification accuracy (94.6%). All models were more accurate than the mean regressors for both DOS and LOS predictions.

We successfully demonstrated that MLMs can be used to accurately predict the DOS and LOS of SLD based on preoperative factors. This big-data application has significant practical implications with respect to surgical scheduling and inpatient bedflow, as well as major implications for both private and publicly funded healthcare systems. Incorporating this artificial intelligence technique in real-time hospital operations would be enhanced by including institution-specific operational factors such as surgical team and operating room workflow.

Introduction

Wolff's Law proposes that trabecular bone adapts in response to mechanical loading and that trabeculae align with the trajectory of predominant loads. The current study is aimed to investigate trabecular orientation in the tibia in patients with osteoarthritis of the knee. Consistent with Wolff's Law, it was hypothesised that orientation would reflect the mechanical loading of the joint and hence that there would be a correlation between the trabecular orientation and the mechanical axis of the lower limb.

Blockade of the suprascapular nerve (SSN) with local anaesthetic is used frequently in shoulder surgery and for chronic shoulder pain. Anatomical landmarks may be used to locate the nerve prior to infiltration with local anaesthetic, but ultrasound is becoming a popular to locate the nerve.

Twelve cadaveric shoulders from 6 specimens were injected with dye using the landmark and ultrasound technique. The shoulders were scanned with computed tomography, and then dissected to ascertain the accuracy of each technique.

Using CT scan results, we found the ultrasound group to be more accurate in placing the anaesthetic needle close to the suprascapular notch, and therefore nerve, and this was significant (p = 0.0009). When analysing the ink data, although we did not observe a significant difference in amount of nerve covered by ink, we did note a correlation, and, given this study group is small, that may be considered a statistical trend.

This study, which is one of the largest cadaveric studies investigating landmark and ultrasound guided block of the suprascapular nerve and we believe the first to use CT, demonstrates that ultrasound guided block is significantly more accurate than the landmark technique, and would therefore recommend that ultrasound guidance be used when blocking the suprascapular nerve, given its higher accuracy and lower complication rate.

Last minute cancellations of operations are a major waste of NHS resources. This study identifies the number of late cancellations at our elective orthopaedic centre, the reasons for them, the costs involved, and whether they are avoidable.

Last minute cancellations of operations in a 7-month period from January to July 2009 were examined.

172 cases out of 3330 scheduled operations were cancelled at the last minute (5.2%). Significantly more cancellations occurred during the winter months due to seasonal illness.

The commonest causes for cancellation in descending order of frequency were patient unfit/unwell (n=76, 44.2%), lack of theatre time (n=32, 18.6%), patient self cancelled/DNA (n=20, 11.6%), staff unavailable or sick (n=9, 5.2%), theatre or equipment problem (n=8, 4.7%), operation no longer required (n=8, 4.7%), administrative error (n=7, 4.1%) or no bed available (n=5, 2.9%). In 7 out of the 172 cancelled cases (4.1%) no cause was identified. 59.7% of the cases were potentially avoidable.

3.2% of Patients seen in the specialist pre-operative anaesthetic clinic (POAC) were cancelled at the last minute for being unfit or unwell, compared to 2.2% seen in the routine nurse led clinic. Last minute cancellations cost the hospital over £700,000 in 7 months.