Monitoring surgical performance: an application to total hip replacement

Control Charts Usage for Monitoring Performance in Surgery: A Systematic Review

OBJECTIVES

The control chart is a graphical tool for data interpretation that detects aberrant variations in specific metrics, ideally leading to the identification of special causes that can be resolved. A clear assessment of control chart utilization and its potential impact in surgery is required to justify recommendations for its dissemination. This review aims to describe how performance monitoring using control charts was used over time in surgery.

METHODS

A systematic search of PubMed regarding statistical process control in surgery from its inception until December 2019 was performed using Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Information extracted from selected publications included study aim and population setting, monitored indicators, control charts methodological parameters, and implementation strategy.

RESULTS

One hundred thirteen studies met the selection criteria with a median of 1916 monitored patients. Overall, 57.5% of studies focused on control chart methodology, 24.8% aimed at evaluating performance changes using control charts retrospectively, and 17.7% implemented control charts for continuous quality improvement prospectively. Although there was a great diversity of used indicators and charting tools, the evaluation of patient safety (72.6%) or efficiency (15.9%) metrics based on Shewhart control chart (33.6%) or cumulative sum chart (54.9%) were common. To foster control charts implementation, 14 studies promoted their periodic review, but only three assessed their impact on patient outcomes.

CONCLUSIONS

The scientific literature supports the feasibility and utility of control chart to improve patient safety in multiple surgical settings. Additional studies are necessary to reveal the optimal manner in which to implement this affordable tool in surgical practice.

Cup placement in primary total hip arthroplasty: how to get it right without navigation or robotics

Acetabular component orientation and position are important factors in the short- and long-term outcomes of total hip arthroplasty.

Different definitions of inclination and anteversion are used in the orthopaedic literature and surgeons should be aware of these differences and understand their relationships.

There is no universal safe zone.

Preoperative planning should be used to determine the optimum position and orientation of the cup and assess spinopelvic characteristics to adjust cup orientation accordingly.

A peripheral reaming technique leads to a more accurate restoration of the centre of rotation with less variability compared with a standard reaming technique.

Several intraoperative landmarks can be used to control the version of the cup, the most commonly used and studied is the transverse acetabular ligament.

The use of an inclinometer reduces the variability associated with the use of freehand or mechanical alignment guides.

Monitoring Hospital Performance with Statistical Process Control After Total Hip and Knee Arthroplasty: A Study to Determine How Much Earlier Worsening Performance Can Be Detected

BACKGROUND

Given the low early revision rate after total hip arthroplasty (THA) and total knee arthroplasty (TKA), hospital performance is typically compared using 3 years of data. The purpose of this study was to assess how much earlier worsening hospital performance in 1-year revision rates after THA and TKA can be detected.

METHODS

All 86,468 THA and 73,077 TKA procedures performed from 2014 to 2016 and recorded in the Dutch Arthroplasty Register were included. Negative outlier hospitals were identified by significantly higher O/E (observed divided by expected) 1-year revision rates in a funnel plot. Monthly Shewhart p-charts (with 2 and 3-sigma control limits) and cumulative sum (CUSUM) charts (with 3.5 and 5 control limits) were constructed to detect a doubling of revisions (odds ratio of 2), generating a signal when the control limit was reached. The median number of months until generation of a first signal for negative outliers and the number of false signals for non-negative outliers were calculated. Sensitivity, specificity, and accuracy were calculated for all charts and control limit settings using outlier status in the funnel plot as the gold standard.

RESULTS

The funnel plot showed that 13 of 97 hospitals had significantly higher O/E 1-year revision rates and were negative outliers for THA and 7 of 98 hospitals had significantly higher O/E 1-year revision rates and were negative outliers for TKA. The Shewhart p-chart with the 3-sigma control limit generated 68 signals (34 false-positive) for THA and 85 signals (63 false-positive) for TKA. The sensitivity for THA and TKA was 92% and 100%, respectively; the specificity was 69% and 51%, respectively; and the accuracy was 72% and 54%, respectively. The CUSUM chart with a 5 control limit generated 18 signals (1 false-positive) for THA and 7 (1 false-positive) for TKA. The sensitivity was 85% and 71% for THA and TKA, respectively; the specificity was 99% for both; and the accuracy was 97% for both. The Shewhart p-chart with a 3-sigma control limit generated the first signal for negative outliers after a median of 10 months (interquartile range [IQR] = 2 to 18) for THA and 13 months (IQR = 5 to 18) for TKA. The CUSUM chart with a 5 control limit generated the first signal after a median of 18 months (IQR = 7 to 22) for THA and 21 months (IQR = 9 to 25) for TKA.

CONCLUSIONS

Monthly monitoring using CUSUM charts with a 5 control limit enables earlier detection of worsening 1-year revision rates with accuracy so that initiatives to improve care can start earlier.

Comparative learning curves for early complications in anatomical and reverse shoulder arthroplasty

Introduction There has been a significant increase in the implantation of reverse shoulder replacements over anatomical shoulder replacements in the past five years. Few comparative data exist comparing early complication rates and learning curves. This study aimed to evaluate the early complication rates and learning curves of a single surgeon series of anatomical and reverse shoulder replacements over the first five years of independent practice. Materials and methods The first 100 anatomical and 100 reverse shoulder replacements performed between July 2011 and July 2016 were reviewed to identify early complications. Cumulative sum plots were used to analyse the learning-curve effect. Results Early complications were noted in 4 anatomical and 17 reverse shoulder replacements. One of the anatomical and ten of the reverse shoulder replacements required a return to theatre within three months. The early complication rates were observed to be significantly higher in the reverse shoulder replacement group compared with the anatomical shoulder replacement group (odds ratio 4.9; 95% confidence interval 1.6-15.2, P 1/4 0.057). An inflection point on the anatomical shoulder replacement cumulative sum plot suggestive of a trend to consistent performance was reached at 16 cases. No inflection point was observed on the reverse shoulder replacement cohort. Conclusions We observed a significantly higher early complication rate within the reverse shoulder replacement cohort, with a tenfold increase in early reoperations. In comparison to the trend seen after 16 cases for anatomical shoulder replacement, no trend was seen in the reverse shoulder replacement cohort. This either reflects the higher complication rate seen in reverse shoulder replacement or that the learning curve extends beyond 100 cases, highlighting the need for extended performance monitoring.

Total Hip Arthroplasty by the Direct Anterior Approach Using a Neck-preserving Stem: Safety, efficacy and learning curve

BACKGROUND

The concept of femoral neck preservation in total hip replacement (THR) was introduced in 1993. It is postulated that retaining cortical bone of the femoral neck offers triplanar stability, uniform stress distribution, and accommodates physiological anteversion. However, data on safety, efficacy and learning curve are lacking.

MATERIALS AND METHODS

We prospectively assessed all patients who were operated for a THR with a short neck preserving stem (MiniHip) between 2012 and 2014. The safety and learning curve were assessed by recording operative time; stem size; and adverse events including periprosthetic fracture; paresthesia; and limb length discrepancy (LLD). The cohort was divided into equal groups to assess the learning curve effect, and the cumulative sums (CUSUM) test was performed to monitor intraoperative neck fractures. For assessment of efficacy, Oxford Hip Score (OHS) and Short Form-36 (SF-36) scores were compared preoperatively and postoperatively.

RESULTS

138 patients with median age 62 years (range 35-82 years) were included with a median followup of 42 months (range 30-56 months). The minimum followup was 2.5 years. The OHS, SF-36 (physical and mental component) scores improved by a mean score of 26, 28, and 27 points, respectively. All patients had LLD of <10 mm (1.9 mm ± 1.3). Adverse events included intraoperative neck fracture (n = 6), subsidence (n = 1), periprosthetic fracture (n = 1), paresthesia (n = 12), and trochanteric bursitis (n = 2). After early modification of the technique to use a smaller finishing broach, the CUSUM test demonstrated acceptable intraoperative neck fracture risk. The second surgery group had a reduced risk of intraoperative neck fracture (5/69 vs. 1/69 P = 0.2), reduced operative time (66 vs. 61 min, P = 0.06), and increased stem size (5 vs. 6, P = 0.09) although these differences were not statistically significant.

CONCLUSIONS

The MiniHip stem is safe alternative to standard THR with good functional outcomes but with a learning curve for the surgical technique, implants sizing, and the risk of intraoperative neck fractures.

A Bayesian CUSUM plot: Diagnosing quality of treatment

OBJECTIVES

To present a CUSUM plot based on Bayesian diagnostic reasoning displaying evidence in favour of "healthy" rather than "sick" quality of treatment (QOT), and to demonstrate a technique using Kaplan-Meier survival curves permitting application to case series with ongoing follow-up.

METHODS

For a case series with known final outcomes: Consider each case a diagnostic test of good versus poor QOT (expected vs. increased failure rates), determine the likelihood ratio (LR) of the observed outcome, convert LR to weight taking log to base 2, and add up weights sequentially in a plot showing how many times odds in favour of good QOT have been doubled. For a series with observed survival times and an expected survival curve: Divide the curve into time intervals, determine "healthy" and specify "sick" risks of failure in each interval, construct a "sick" survival curve, determine the LR of survival or failure at the given observation times, convert to weights, and add up.

RESULTS

The Bayesian plot was applied retrospectively to 39 children with acute lymphoblastic leukaemia with completed follow-up, using Nordic collaborative results as reference, showing equal odds between good and poor QOT. In the ongoing treatment trial, with 22 of 37 children still at risk for event, QOT has been monitored with average survival curves as reference, odds so far favoring good QOT 2:1.

CONCLUSION

QOT in small patient series can be assessed with a Bayesian CUSUM plot, retrospectively when all treatment outcomes are known, but also in ongoing series with unfinished follow-up.

Patient injuries in primary total hip replacement

Background and purpose - Although the results of primary total hip replacements (THRs) are generally excellent, sometimes serious complications arise. Some of these severe complications are considered to be patient injuries. We analyzed primary THR-related patient injuries in a nationwide setting. Patients and methods - We evaluated all the primary THR-related patient injury claims in Finland between 2008 and 2010. We used the original medical records and 2 nationwide registries, the Care Register for Social Welfare and Health Care and the Patient Injury Claim Register. Results - We identified 563 claims, 44% of which were compensated (n = 250). Of these 250 compensated claims, 79% were considered to be avoidable (treatment injuries) and 21% were severe unexpected infections (with a preoperative infection risk of less than 2%). The most common type of technical error was cup malposition (31%). High-volume hospitals (with an annual primary THR volume ≥ 400) had a lower patient injury rate. In lower-volume hospitals (with an annual primary THR volume of < 400), the relative risks (RRs) of patient injury for any reason, due to technical errors, or because of cup malposition were 2-fold (95% CI: 1.6-3.1), 4-fold (95% CI: 2.3-6.2), and 9-fold (95% CI: 3-28), respectively, compared to high-volume hospitals. Interpretation - Our study provides the first comprehensive nationwide data on THR-related patient injury types. Hospital volume was associated with the quality and quantity of errors detected. An annual hospital volume of ≥ 400 primary THRs was established as a protective factor against patient injuries.

Monitoring the quality of robot-assisted pedicle screw fixation in the lumbar spine by using a cumulative summation test

STUDY DESIGN

Prospective randomized controlled trial.

OBJECTIVE

The aim of this study was to monitor the quality control of robot-assisted pedicle screw fixation accuracy by using a cumulative summation (CUSUM) test at the initial stage of its application.

SUMMARY OF BACKGROUND DATA

Although robot-assisted pedicle screw fixation reduces screw misplacement rates and provides critical support for minimally invasive surgical procedures, there have been no reports relating to the monitoring of quality control of the accuracy of this robot-assisted pedicle screw fixation procedure.

METHODS

Patients with lumbar spinal stenosis scheduled to undergo surgery were randomly and equally assigned through 1:1 allocation to a robot-assisted minimally invasive posterior lumbar interbody fusion (Rom-PLIF) group or a conventional open posterior PLIF using freehand technique group. The accuracy of pedicle screw placement was evaluated using postoperative computed tomography. The primary outcome was the CUSUM analysis for monitoring the quality control of the accuracy of pedicle screw insertion between the Rom-PLIF and conventional open posterior PLIF using freehand technique groups.

RESULTS

Of the 80 pedicle screws inserted in each group, 4 screws in the Rom-PLIF group, and 7 in the conventional open PLIF group, breached the pedicle. Of these 11 offending screws, 4 cases were categorized as grade B in the Rom-PLIF group, whereas 6 were grade B and 1 case was grade C in the Com-PLIF group, using the Gertzbein and Robbins classification. Throughout the monitoring period, there was no CUSUM test-derived indication that the quality of performance of the pedicle screw fixation procedure was inadequate in either group.

CONCLUSION

First, this study demonstrates the adequacy of quality control of robot-assisted pedicle screw fixation even early in the application period based on the CUSUM analysis. Second, the CUSUM test can be a useful tool for monitoring of the quality of procedures related with spine surgery.

Learning curve of acetabular cup positioning in total hip arthroplasty using a cumulative summation test for learning curve (LC-CUSUM)

Despite advances in surgical techniques and instrumentation, optimal cup positioning in total hip arthroplasty (THA) is challenging with a limited accuracy. We evaluated whether a learning curve exists for the optimal cup positioning, using the LC-CUSUM test (Learning curve cumulative summation test). We evaluated the first 100 consecutive THA performed by two surgeons, who had a year of fellowship training in the same teaching hospital. A learning curve of cup positioning was plotted in each series using the LC-CUSUM score. There was no significant difference of numbers of outlier between two surgeons (P = 0.079). Both surgeons completed the learning curve of optimal cup positioning before 50 procedures, and maintained competence. A substantial learning period is necessary in the optimal positioning of an acetabular cup.

Monitoring the one year postoperative infection rate after primary total hip replacement

PURPOSE

Infection of a total hip replacement is potentially a devastating complication. Statistical process control methods have been generating interest as a means of improving the quality of healthcare, and we report our experience with the implementation of such a method to monitor the one year infection rate after primary total hip replacement.

METHOD

Infection was defined as the growth of the same organism in cultures of at least two aspirates or intra-operative specimens, or growth of one pathogen in a patient with local signs of infection such as erythema, abscess or draining sinus tract. The cumulative summation test (CUSUM test) was used to continuously monitor the one year postoperative infection rate. The target performance was 0.5% and the test was set to detect twice that rate.

RESULTS

Over the three year study period, 2006 primary total hip replacements were performed. Infection developed within one year after surgery in eight (0.4%) hips. The CUSUM test generated no alarms during the study period, indicating that there was no evidence that the process was out of control.

CONCLUSION

The one year infection rate after primary total hip replacement was in control. The CUSUM test is a useful method to continuously ensure that performance is maintained at an adequate level.

[Templating and radiological outcome monitoring for elective total hip arthroplasty. Applied quality management principles for safe patient care]

Implementation of total hip arthroplasty is a successful and reliable treatment for end-stage osteoarthritis. The biomechanics and components as well as the fixation were selected with the aid of templating. Based on a cohort of 114 patients the quality of digital X-rays and the operative results were determined. There was a slight leg lengthening and a good offset reconstruction in these patients. For the patients with replacement of the second hip the leg lengthening was smaller. The cup inclination was at 43° and 44° within the desired range. The prediction of the exact component size used was 40% for the cup and 29% for the stem.Through variation in scaling of the digital X-ray a diminishing prediction accuracy was found in our study. The correction of biomechanics and position of components showed good quality in patient care. Templating and assessment of the postoperative result in total hip arthroplasty is a model for continuous quality management and can be recommended for safe patient care.

Monitoring the quality of total hip replacement in a tertiary care department using a cumulative summation statistical method (CUSUM)

The purpose of this study was to define immediate post-operative ‘quality’ in total hip replacements and to study prospectively the occurrence of failure based on these definitions of quality. The evaluation and assessment of failure were based on ten radiological and clinical criteria. The cumulative summation (CUSUM) test was used to study 200 procedures over a one-year period. Technical criteria defined failure in 17 cases (8.5%), those related to the femoral component in nine (4.5%), the acetabular component in 32 (16%) and those relating to discharge from hospital in five (2.5%). Overall, the procedure was considered to have failed in 57 of the 200 total hip replacements (28.5%). The use of a new design of acetabular component was associated with more failures. For the CUSUM test, the level of adequate performance was set at a rate of failure of 20% and the level of inadequate performance set at a failure rate of 40%; no alarm was raised by the test, indicating that there was no evidence of inadequate performance.

The use of a continuous monitoring statistical method is useful to ensure that the quality of total hip replacement is maintained, especially as newer implants are introduced.

Monitoring surgical performance: an application of industrial quality process control to anterior cruciate ligament reconstruction

Quality control is receiving increasing attention from surgeons as a key to meeting the needs of patients and the requirements of health care authorities. The objective of the study was to evaluate a continuous monitoring program for surgical performance in anterior cruciate ligament reconstruction. We measured the differential anterior knee laxity immediately after anterior cruciate ligament reconstruction by two experienced surgeons. Surgical technique including the choice of ancillary devices and implant material was at the surgeon's discretion. The target was an immediate postoperative differential knee laxity at 20 degrees of knee flexion of -1.5 mm. The cumulative summation test (CUSUM) was used to detect inadequate performance. Seventy-nine consecutive patients were included in the study. Median postoperative differential knee laxity at 20 degrees flexion was -2 mm (interquartile range -4 to 0 mm; SD = 2.3). The CUSUM test at 20 degrees knee flexion emitted an alarm at the 12th procedure, indicating that performance was inadequate with a tendency for laxity to be above the target of -1.5 mm. Two alarms were emitted after the 28th procedure, indicating that laxity tended to be below the target. Monitoring of immediate postoperative differential anterior knee laxity in anterior cruciate ligament reconstruction is feasible and can provide useful information on actual surgeon performance.

CLINICAL RELEVANCE

continuous monitoring of the quality of anterior cruciate ligament reconstruction may help surgeons to detect deviations from optimal performance when new surgical techniques and innovative fixation devices are introduced.