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

A monitoring tool for performance improvement in plastic surgery at the individual level

BACKGROUND

The assessment of performance in surgery is expanding significantly. Application of relevant frameworks to plastic surgery, however, has been limited. In this article, the authors present two robust graphic tools commonly used in other industries that may serve to monitor individual surgeon operative time while factoring in patient- and surgeon-specific elements.

METHODS

The authors reviewed performance data from all bilateral reduction mammaplasties performed at their institution by eight surgeons between 1995 and 2010. Operative time was used as a proxy for performance. Cumulative sum charts and exponentially weighted moving average charts were generated using a train-test analytic approach, and used to monitor surgical performance. Charts mapped crude, patient case-mix-adjusted, and case-mix and surgical-experience-adjusted performance.

RESULTS

Operative time was found to decline from 182 minutes to 118 minutes with surgical experience (p < 0.001). Cumulative sum and exponentially weighted moving average charts were generated using 1995 to 2007 data (1053 procedures) and tested on 2008 to 2010 data (246 procedures). The sensitivity and accuracy of these charts were significantly improved by adjustment for case mix and surgeon experience.

CONCLUSIONS

The consideration of patient- and surgeon-specific factors is essential for correct interpretation of performance in plastic surgery at the individual surgeon level. Cumulative sum and exponentially weighted moving average charts represent accurate methods of monitoring operative time to control and potentially improve surgeon performance over the course of a career.

Optimal measurement of clinical rotational test for evaluating anterior cruciate ligament insufficiency

PURPOSE

Rotational instability in ACL insufficient knee addresses the symptom or the abnormal motion which can be reproduced and subjectively evaluated in the clinical exam. Clinically available quantitative measurement for this instability has not been established due to mixed testing maneuvers and complex kinematics. The purpose was to measure knee kinematics during three manually performed rotational tests and to determine the optimal method to detect the abnormality in ACL deficient knees.

METHOD

Thirteen unilateral ACL deficient patients were tested by internal and external pure rotational stress tests and pivot shift test under anesthesia before scheduled ACL reconstructions. Rotation and coupled motion, i.e., tibial anteroposterior translation, were measured using an electromagnetic measurement system. Additionally, the acceleration of the tibial posterior translation during pivot shift test was calculated. The differences of these parameters between ACL intact and deficient knees were tested.

RESULTS

Knee rotation is not different between ACL intact and deficient during both pure rotational stress test and pivot shift test. The coupled anterior tibial translation during pivot shift test was significantly different between ACL intact, 13.5 ± 4.1 mm, and deficient knees, 23.1 ± 4.4 mm, (P < 0.01) as well as the acceleration of the tibial posterior translation (1.1 ± 0.4 m/sec(2) in intact knees, 3.2 ± 1.5 m/sec(2) in deficient knees; P < 0.01). The coupled motion during pure rotational stress tests was similar regardless of ACL condition.

CONCLUSION

The rotational instability of the ACL deficiency was reproduced only by the pivot shift test and detected only by measuring the tibial anteroposterior translation and acceleration of the tibial posterior reduction. Level of evidence Diagnostic study, Level III.

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.

Combined unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction

PURPOSE

Patients presenting anterior cruciate ligament (ACL) deficiency and isolated osteoarthritis of the medial compartment are treated either with biplanar osteotomy or with total knee arthroplasty (TKA). However, these patients between the forties and fifties are often very active in daily life and feel limited due to their knee. In order to follow the idea of preserving as much as possible from the joint, the concept of unicondylar joint replacement in conjunction with ACL reconstruction has been followed. There seems to be a limited experience with this concept. The purpose of the follow-up study was to evaluate the midterm clinical and functional outcome.

METHODS

Twenty-seven patients were followed up for 53 months. The mean age of the 11 men and 16 women was 44 years. All patients were treated by combined unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction.

RESULTS

The Knee Society Score improved significantly from 77.1 ± 11.6 points to 166.0 ± 12.1 points (P ≤ 0.01). No revision surgery was required and no radiolucent lines were observed on the radiographs at the time of follow-up. The anterior translation showed less than 5 mm in 24 patients and 5 mm in the remaining 3 patients.

CONCLUSIONS

The midterm clinical data have shown that combined surgery of UKA and anterior cruciate ligament reconstruction has revealed promising results. The restored knee stability seems to prevent the failure of UKA. However, long-term follow-up studies are required in these patients who received partial joint replacement fairly early in their life.

LEVEL OF EVIDENCE

IV.

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.