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

Defining the Learning Period of a Novel Imageless Navigation System for Posterior Approach Total Hip Arthroplasty: Analysis of Surgical Time and Accuracy

Introduction

The use of imageless navigation in total hip arthroplasty (THA) is frequently associated with prolonged surgical times, predominantly during the learning period. The purpose of the present study was to characterize the learning period of a novel imageless navigation system, specifically as it related to surgical time and acetabular navigation accuracy.

Materials and Methods

This was a retrospective observational study of a consecutive group of 158 patients who underwent primary unilateral THA for osteoarthritis by a team headed by a single surgeon. All procedures used an imageless navigation system to measure acetabular cup inclination and anteversion angles, referencing a generic sagittal and frontal plane. Navigation accuracy was determined by assessing differences between intraoperative inclination and anteversion values and those obtained from standardized 6-week follow-up radiographs. Operative time and navigation accuracy were assessed by plotting moving averages of 7 consecutive cases. The learning period was defined using Mann-Kendall trend analyses, student t-tests and nonlinear regression modeling based on surgical time and navigation accuracy. Alpha error was 0.05.

Results

The average surgical time was 67.3 min (SD:9.2) (range 45-95). The average navigation accuracy for inclination was 0.01° (SD:4.2) (range - 10 to 10), and that for anteversion was - 4.9° (SD:3.8) (range - 14 to 5). Average surgical time and navigation accuracy were similar between the first and final cases in the series with no learning period detected.

Conclusions

There was no discernible learning period effect on surgical time or system measurement accuracy during the early phases of adoption for this imageless navigation system.

Hip fracture surgery performed by cadaveric simulation-trained versus standard-trained orthopaedic trainees: a preliminary multicentre randomized controlled trial

Aims

To evaluate if, for orthopaedic trainees, additional cadaveric simulation training or standard training alone yields superior radiological and clinical outcomes in patients undergoing dynamic hip screw (DHS) fixation or hemiarthroplasty for hip fracture.

Methods

This was a preliminary, pragmatic, multicentre, parallel group randomized controlled trial in nine secondary and tertiary NHS hospitals in England. Researchers were blinded to group allocation. Overall, 40 trainees in the West Midlands were eligible: 33 agreed to take part and were randomized, five withdrew after randomization, 13 were allocated cadaveric training, and 15 were allocated standard training. The intervention was an additional two-day cadaveric simulation course. The control group received standard on-the-job training. Primary outcome was implant position on the postoperative radiograph: tip-apex distance (mm) (DHS) and leg length discrepancy (mm) (hemiarthroplasty). Secondary clinical outcomes were procedure time, length of hospital stay, acute postoperative complication rate, and 12-month mortality. Procedure-specific secondary outcomes were intraoperative radiation dose (for DHS) and postoperative blood transfusion requirement (hemiarthroplasty).

Results

Eight female (29%) and 20 male trainees (71%), mean age 29.4 years, performed 317 DHS operations and 243 hemiarthroplasties during ten months of follow-up. Primary analysis was a random effect model with surgeon-level fixed effects of patient condition, patient age, and surgeon experience, with a random intercept for surgeon. Under the intention-to-treat principle, for hemiarthroplasty there was better implant position in favour of cadaveric training, measured by leg length discrepancy ≤ 10 mm (odds ratio (OR) 4.08 (95% confidence interval (CI) 1.17 to 14.22); p = 0.027). There were significantly fewer postoperative blood transfusions required in patients undergoing hemiarthroplasty by cadaveric-trained compared to standard-trained surgeons (OR 6.00 (95% CI 1.83 to 19.69); p = 0.003). For DHS, there was no significant between-group difference in implant position as measured by tip-apex distance ≤ 25 mm (OR 6.47 (95% CI 0.97 to 43.05); p = 0.053). No between-group differences were observed for any secondary clinical outcomes.

Conclusion

Trainees randomized to additional cadaveric training performed hip fracture fixation with better implant positioning and fewer postoperative blood transfusions in hemiarthroplasty. This effect, which was previously unknown, may be a consequence of the intervention. Further study is required.

Learning Curve of USgHIFU Ablation for Uterine Fibroids: A Multi-Center Prospective Study

OBJECTIVES

To verify the stability of high-intensity focused ultrasound (HIFU) technology and the feasibility of training programs with learning curve cumulative summation (LC-CUSUM).

METHODS

A total of 12 physicians and 720 cases were equally assigned to the learning group and the control group, with 6 physicians and 360 cases per group. The learning group was treated by physicians without HIFU experience and the control group was treated by experienced physicians. Nonperfused volume (NPV) ratio was assessed by contrast-enhanced magnetic resonance imaging. Technical failure was defined as NPV ratio of uterine fibroids <70% and/or major complication, while <80% was set as a stricter standard of training qualification. LC-CUSUM was used to analyze the learning curve.

RESULTS

Physicians with or without HIFU experience in both groups achieved matchable NPV ratios, where a NPV ratio of 92.52% (16.06) was achieved by experienced physicians and 93.82% (16.95) by inexperienced physicians. No major complication was observed. The results of LC-CUSUM analysis showed that, with the standards of the NPV ratio of 70% or 80%, the learning group mastered the technique on the 11th case and the 16th case, respectively, while the control group was stable.

CONCLUSIONS

HIFU technology stayed stable in operation, with good safety and sound effectiveness, and was easy to learn. NPV ratio of 70% was considered as an appropriate indicator of training qualification. HIFU has remarkable prospects in achieving a NPV ratio of ≥80% without safety being compromised.

Learning curve for microscopic unilateral laminectomy for bilateral decompression surgery using the cumulative summation test for learning curve

A retrospective observational study The purpose of this study was to characterize the learning curve for a single level unilateral laminectomy and bilateral decompression in lumbar spinal stenosis using a learning curve cumulative summation test. Unilateral laminectomy and bilateral decompression for lumbar spinal stenosis proposes a potential benefit with minimizing surgery-related instability compared to traditional bilateral laminectomy, by preserving posterior stabilizing structures and contralateral facet joint and neural arch. Due to a narrow surgical corridor, it is considered to exhibit a steep learning curve as other types of minimally invasive procedures. However, there are few reports available regarding learning curve of unilateral laminectomy and bilateral decompression. The learning curve of a single surgeon performing single level unilateral laminectomy and bilateral decompression was assessed using learning curve cumulative summation test analysis. The surgeon had minimal experience in open decompressive laminectomy but no previous experience in unilateral laminectomy and bilateral decompression. Procedure success was defined as an operation time less than 75 minutes. Surgery related complications were recorded. Total 194 consecutive patients, who underwent primary single level unilateral laminectomy and bilateral decompression by a single spine surgeon, were included. The mean operative time for unilateral laminectomy and bilateral decompression was 64.6 ± 23.6 minutes. The mean operative time in the early learning period (≤29th case) was 80.6 ± 20.9 minutes, and that in the late learning period (after 29th case) was 61.8 ± 22.7 minutes, respectively. The overall complication rate was 13.9%. Majority of complications occurred in the early learning period. The learning curve cumulative summation test signaled competency for unilateral laminectomy and bilateral decompression at the 29th operation, indicating that the surgeon reached the competent level. In addition, based on the cumulative summation test, the surgeon seemed to maintain his competency for the procedure. This study showed that surgical experience reduced the operation time and surgery related complications. For inexperienced surgeon to achieve an acceptable outcome in unilateral laminectomy and bilateral decompression, minimum 30 cases of unilateral laminectomy and bilateral decompression are required to reach competent level of surgery.

Total Hip Arthroplasty with Robotic Arm Assistance for Precise Cup Positioning: A Case-Control Study

OBJECTIVE

To determine whether more precise cup positioning can be achieved with robot-assisted total hip arthroplasty (THA) as compared to conventional THA.

METHODS

In this study, between July 2019 and May 2021, 93 patients aged 23-75 years with osteonecrosis of the femoral head (ONFH) and adult developmental dysplasia of hip who underwent first hip surgery were included in the study. They were randomly assigned to either the robotic-assisted THA group (n = 45) or the conventional THA group (n = 48). After the operation, all patients were given routine rapid rehabilitation guidance. The duration of operation was recorded to estimate the learning curve through cumulative summation analysis. We compared the demographics, duration of operation, cup positioning, leg length discrepancy, hip offset, and Harris Hip Score between robot-assisted THA and manual THA. Precision in the positioning of the acetabular prosthesis using the MAKO system was also compared between the two groups.

RESULTS

The mean duration of operation for the robot-assisted THA group was 91.37 ± 17.34 min (range: 63 to 135 min), which was significantly higher than that for the conventional THA group. When the number of procedures was increased to 13, the duration of operation in the robot-assisted group decreased significantly and gradually became stable. In terms of duration of operation, robot-assisted THA was associated with a learning curve of 13 cases. The mean amount of bleeding in the robot-assisted THA group was not significantly different from that in conventional THA group (328 ± 210 ml vs 315 ± 205 ml) (p = 0.741). There was no significant difference in the proportion of prostheses located within Lewinnek's safe zone between robot-assisted THA group and conventional THA group (69.81% vs 64.41%). The leg length discrepancy (LLD) was significantly smaller in the robot-assisted THA group than in the conventional THA group (p < 0.001), but both were within acceptable limits (10 mm). The inclination and anteversion angles of the acetabular prosthesis planned before operations were correlated with the actual measurement (r = 0.857 p < 0.001, r = 0.830, p < 0.001). After surgery, none of the patients experienced hip dislocation, aseptic loosening, or periprosthetic infection during the 3 months of follow-up.

CONCLUSION

The proportion of acetabular prostheses in the Lewinnek's safety zone was higher and the extent of LLD was significantly lower in the robot-assisted THA group, as compared to the same metrics in the conventional THA group. The MAKO robot improved the accuracy of implant placement in THA.

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.

Learning Curve of Total Hip Arthroplasty in Direct Anterior Approach without Requiring Corrective Osteotomy for Hip Dysplasia

OBJECTIVE

To explore the learning curve of total hip arthroplasty in direct anterior approach (DA-THA) without requiring corrective osteotomy for patients with unilateral developmental dysplasia of the hip (DDH) through the evaluation of clinical and radiographic results.

METHOD

From December 2015 to January 2021, we retrospectively evaluated a surgeon's first 100 patients with unilateral hip dysplasia (Crowe I-III) who underwent DA-THA. All procedures were performed by a fellowship-trained joint surgeon. Cementless hemispheric porous-coated acetabular cups and tapered cementless stems were used in all hips. The radiographic data, including leg length, the height of the center of rotation, femoral head offset, the cup anteversion and inclination angle, were measured. The cumulative sum analysis (CUSUM) and risk-adjusted cumulative sum analysis (RA-CUSUM) were used to determine the learning curve of DA-THA for each patient's operation time. By analyzing the operation time, complication rate, postoperative length of hospitalization and creatine kinase (before surgery and the third day after surgery), estimated blood loss, Harris score, radiographic data were compared between the different stages of the learning curve.

RESULTS

The mean follow-up time was 35.45 ± 16.82 months. The CUSUM method obtained the maximum turning point of the curve at 43 cases, which divided the learning curve into Learning Period and Mastery Period. The CUSUM learning curve was best modeled as a cubic curve with the equation: CUSUM (min) = 0.001x³  - 0.495x²  + 33.60x - 10.00, which had a higher R² value of 0.967. The pre-operative data, creatine kinase, estimated blood loss and postoperative Harris scores of the two stages were not statistically significant (P > 0.05). The mean operation time was 118 min in the Learning Period and 87 min in the Mastery Period. Statistically significant differences were detected in the operation time (P < 0.001), postoperative length of hospitalization(P = 0.024), and postoperative leg length discrepancy (P = 0.012) between the two stages. The overall complication rates were 27.9% in the Learning Period and 12.3% in the Mastery Period (p = 0.049). The overall outliers of radiographic data were 34 cases in the Learning Period and 31 cases in the Mastery Period (79.07% vs 54.39%, P = 0.010).

CONCLUSIONS

The DA-THA is a valuable alternative to achieve satisfactory clinical results for mild-to-moderate DDH patients. Furthermore, accurate analysis of the learning curve of DA-THA for hip dysplasia by the CUSUM method showed that the surgeons need to finish about 43 cases to master the technique.

Short-Term Clinical Assessment of Hip Hemi-Arthroplasty in 11 Dogs

OBJECTIVE

 The aim of this study was to assess the short-term clinical outcome in dogs following a hip hemi-arthroplasty for the treatment of primary pathological disorders of the hip and as a salvage procedure following failure of the cup component of a total hip replacement.

MATERIALS AND METHODS

 Medical records of dogs that had a unilateral hip hemi-arthroplasty performed between 2015 and 2020 were reviewed. Data collected included follow-up orthopaedic examinations performed at 0, 2, 8 and 52 weeks postoperatively, pelvic radiography at 0, 8 and 52 weeks postoperatively and an owner questionnaire (Helsinki chronic pain index [HCPI]).

RESULTS

 Eleven unilateral hip hemi-arthroplasty procedures were identified. The median age at time of surgery was 3.6 years (8 months-10 years) and the median follow-up time was 13 months (range: 2 months-3 years). The HCPI for all dogs at follow-up was median 8 ± 7.30 (range: 5-25). Total HCPI was < 12 for 7/10 dogs and ≥ 12 for 3 dogs. Pelvic radiographs at 1 year confirmed osteointergration of the femoral stem implant and no evidence of implant subsidence or progression of osteoarthritis. However, there was some evidence of mild lucency of the acetabular bed around the prosthetic femoral head and mild peri-acetabular sclerosis in four cases.

CONCLUSION

 Hip hemi-arthroplasty provides a clinically acceptable treatment for disabling disease of the coxofemoral joint with 10/11 patients achieving acceptable short-term clinical function. Long-term assessment of the hip hemi-arthroplasty and comparison with total hip replacement is indicated.

Accuracy of acetabular cup placement positively correlates with level of training

BACKGROUND

Accurate acetabular component placement may reduce the risk of complication after total hip arthroplasty (THA). While surgeon experience and volume may reduce outliers, little is known how cup positioning accuracy and consistency relates to level of training (resident, fellow, attending) and whether trainee level impacts the magnitude and direction of cup placement errors.

METHODS

Ninety patients undergoing posterolateral computer-assisted navigation THA were included for analysis. All surgery was performed by two fellowship-trained orthopaedic surgeons and assisted by a trainee (orthopedic resident (PGY 1-5) or fellow in adult reconstruction). In order to determine accuracy of cup placement in trainees and attendings, we used computer navigation to determine freehand cup placement by the trainee, then by the attending surgeon. Final cup inclination and version were determined and recorded by computer-assisted surgical navigation. Comparison of consistency in cup inclination and anteversion was made on values obtained by residents, fellows, and attendings and final values provided by the navigation system. In addition, to assess the role of training and repetition, acetabular cup inclination and version were compared between fellows during the first half and the second half of their training year. All comparisons were performed with the Student t-test except for comparison of rate of deviation from the safe zone, which were performed with the chi-square test. The level of significance was defined as p values ≤ 0.05 with 95% confidence interval, and trend toward significance was defined as p values ≤ 0.1.

RESULTS

Inclination deviation from the final position and cup version deviation from the final position were statistically significant between resident vs attendings (p < 0.001 (inclination), p < 0.001 (version)), fellow vs attendings (p < 0.001 (inclination), p < 0.001 (version)), and all trainee vs attendings (p < 0.001 (inclination), p < 0.001 (version)). In all comparisons, the attending surgeons placed the cup closer to the final cup position than both resident and fellows. Proportion of inclination deviation from the safe zone of residents was significantly higher than of attendings (p < 0.001) but no significant difference was observed between fellows and attending (p = 1.00). Compared to residents, fellows demonstrated lower proportion of inclination deviation from the safe zone of 3.3% vs 23.3% for fellows vs residents (p = 0.002) and tended to implant the cups in a more horizontal position (45.6 ± 6.6° [SD] and 42.7 ± 4.3°, respectively, p = 0.04). Compared to fellow, residents tended to implant the cup in a more anteverted position than the final cup version (9.6 ± 6.7° and 6.74 ± 5.6° [SD], p = 0.034). There was no statistically significant difference in cup position between attendings' free-hand and final (computer assisted) cup placement.

CONCLUSION

Accurate and consistent acetabular cup placement improves with level of training. Accurate and consistent acetabular cup version is harder to master as compared to acetabular cup inclination.

Can robotic technology mitigate the learning curve of total hip arthroplasty?

Aims

Traditionally, acetabular component insertion during total hip arthroplasty (THA) is visually assisted in the posterior approach and fluoroscopically assisted in the anterior approach. The present study examined the accuracy of a new surgeon during anterior (NSA) and posterior (NSP) THA using robotic arm-assisted technology compared to two experienced surgeons using traditional methods.

Methods

Prospectively collected data was reviewed for 120 patients at two institutions. Data were collected on the first 30 anterior approach and the first 30 posterior approach surgeries performed by a newly graduated arthroplasty surgeon (all using robotic arm-assisted technology) and was compared to standard THA by an experienced anterior (SSA) and posterior surgeon (SSP). Acetabular component inclination, version, and leg length were calculated postoperatively and differences calculated based on postoperative film measurement.

Results

Demographic data were similar between groups with the exception of BMI being lower in the NSA group (27.98 vs 25.2; p = 0.005). Operating time and total time in operating room (TTOR) was lower in the SSA (p < 0.001) and TTOR was higher in the NSP group (p = 0.014). Planned versus postoperative leg length discrepancy were similar among both anterior and posterior surgeries (p > 0.104). Planned versus postoperative abduction and anteversion were similar among the NSA and SSA (p > 0.425), whereas planned versus postoperative abduction and anteversion were lower in the NSP (p < 0.001). Outliers > 10 mm from planned leg length were present in one case of the SSP and NSP, with none in the anterior groups. There were no outliers > 10° in anterior or posterior for abduction in all surgeons. The SSP had six outliers > 10° in anteversion while the NSP had none (p = 0.004); the SSA had no outliers for anteversion while the NSA had one (p = 0.500).

Conclusion

Robotic arm-assisted technology allowed a newly trained surgeon to produce similarly accurate results and outcomes as experienced surgeons in anterior and posterior hip arthroplasty.

Cite this article: Bone Jt Open 2021;2(6):365–370.

The learning curve of robotic-arm assisted acetabular cup positioning during total hip arthroplasty

BACKGROUND

Robotic-arm assisted surgery aims to reduce manual errors and improve the accuracy of implant positioning and orientation during total hip arthroplasty (THA). The objective of this study was to assess the surgical team's learning curve for robotic-arm assisted acetabular cup positioning during THA.

METHODS

This prospective cohort study included 100 patients with symptomatic hip osteoarthritis undergoing primary total THA performed by a single surgeon. This included 50 patients receiving conventional manual THA and 50 patients undergoing robotic-arm assisted acetabular cup positioning during THA. Independent observers recorded surrogate markers of the learning curve including operative times, confidence levels amongst the surgical team using the state-trait anxiety inventory (STAI) questionnaire, accuracy in restoring native hip biomechanics, acetabular cup positioning, leg-length discrepancy, and complications within 90 days of surgery.

RESULTS

Cumulative summation (CUSUM) analysis revealed robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for achieving operative times (p < 0.001) and surgical team confidence levels (p < 0.001) comparable to conventional manual THA. There was no learning curve of robotic-arm assisted THA for accuracy of achieving the planned horizontal (p = 0.83) and vertical (p = 0.71) centres of rotation, combined offset (p = 0.67), cup inclination (p = 0.68), cup anteversion (p = 0.72), and correction of leg-length discrepancy (p = 0.61). There was no difference in postoperative complications between the two treatment groups.

CONCLUSIONS

Integration of robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for operative times and surgical team confidence levels but there was no learning curve effect for accuracy in restoring native hip biomechanics or achieving planned acetabular cup positioning and orientation.

Robotics and Navigation as Learning Tools for Fellows Training in Hip Arthroplasty

INTRODUCTION

The association between implant malpositioning and complications has been repeatedly demonstrated. Recently, technological advancements have allowed for more consistent implant placement. Beyond this obvious application, these technologies may also serve as a learning tool. Thus, the aim of this study was to evaluate the accuracy of fellows' estimation of implant positioning using a robotic system.

METHODS

Data were prospectively collected for all patients undergoing total hip arthroplasty between September 2019 and December 2019. The fellow was blinded to the robotic system. Before reaming and broaching by the senior surgeon, the fellow was asked to place the reamer at 40° of cup inclination and 20° of version. The resulting values were recorded before the true measurements were revealed. A similar process was followed for femoral broaching.

RESULTS

The mean difference between the estimated and actual cup inclination and version was 7.24° (P = 0.060) and 4.81° (P = 0.031), respectively. The mean difference in broach version was 7.00° (P = 0.159). Without the robotic system, 43.47% and 69.57% of patients would have had the cup placed outside of the safe zones described by Lewinnek and Callanan, respectively.

CONCLUSION

The estimated anteversion of the acetabular implant was found to be markedly different from its actual anteversion. A considerable portion of the cups would have been positioned outside of the Lewinnek and Callanan "safe zones" provided that the implants would have been manually positioned. The use of robotic or navigation systems may provide useful learning tools for fellows in training to understand their own inaccuracies in estimated implant position and hence refine their abilities.

Low evidence for implementation of well-documented implants regarding risk of early revision: a systematic review on total hip arthroplasty

When introducing an implant, surgeons are subjected to steep learning curves, which may lead to a heightened revision rate. Stepwise introduction revolutionized implant introduction but lacks a last step.

No guidelines exist for the introduction of a well-documented implant not previously used in a department. This is problematic according to the European Union’s legislated tendering process, potentially leading to increased revisions. In this systematic review, the introduction of a well-documented total hip arthroplasty implant to experienced surgeons is explored amid concerns of higher revision rate.

Literature search strategies were deployed in the Embase and Medline databases, revealing a total of 14,612 articles. Using the Covidence software (Cochrane, London), two reviewers screened articles for inclusion.

No articles were found that fulfilled our eligibility criteria. A post hoc analysis retrieved two national register-based studies only missing information about the surgeon’s knowledge of the introduced implant. None of the introduced implants decreased the revision rate and around 30% of the introduced implants were associated with a higher revision rate.

The review showed that no data exist about revision rates when introducing well-documented implants. In continuation thereof, the introduction of well-documented implants might also be associated with increased revision rates, as has been shown for total knee arthroplasty. We therefore suggest that special attention should be focused on changes of implants in departments, which can be achieved by way of specific registration in national registers.

Cite this article: EFORT Open Rev 2021;6:3-8. DOI: 10.1302/2058-5241.6.200047

HipSim - hip fracture surgery simulation utilizing the Learning Curve-Cumulative Summation test (LC-CUSUM)

Background and purpose - Virtual reality simulation of hip fracture surgery is available for orthopedic residents nationwide in Denmark. Summative assessment of learning applying the learning curve cumulative summation test (LC-CUSUM) has not been utilized in orthopedic simulation training. The strength of the LC-CUSUM is that it assumes incompetency and signals competency based on solid statistics. We investigated the LC-CUSUM characteristics of novices stepwise mastering the simulated dynamic hip screw (DHS) procedure. Material and methods - 32 1st-year orthopedic residents participated in HipSim and its 3 subsequent LC-CUSUM evaluations: placing a Kirschner wire, placing a Kirschner wire in different patients, and performing the entire DHS procedure in different patients. The career status of the participants, i.e., still working in orthopedics or in another specialty was recorded ≥ 2 years after participation and associated with the simulation performance (passed/failed). Results - 13/14 participants passing HipSim according to LC-CUSUM were still working in orthopedics, while 9/18 participants failing HipSim had quit orthopedics at ≥ 2 years follow-up. The simulator-generated feedback did not statistically significantly differ between the groups. Interpretation - LC-CUSUM and its summative pass/fail assessment of each simulation was feasible in this formative simulation program. Clinical educators can be reassured that participants passing HipSim are likely to continue to 2nd-5th year of residency, while failing HipSim should raise concerns and trigger career counselling and clinical supervision. The motivational aspect of LC-CUSUM pass/fail assessment when designing formative simulation training warrants further research.

Is selective nerve root block necessary for learning percutaneous endoscopic lumbar discectomy: a comparative study using a cumulative summation test for learning curve

PURPOSE

The aim of this study was to investigate the effect of lumbar spine selective nerve root block (SNRB) experience on the learning efficiency of percutaneous endoscopic lumbar discectomy (PELD) for junior trainees.

METHODS

A total of 480 patients undergoing single-level PELD performed by eight junior trainees were included. The trainees were divided into two groups based on whether they had previous SNRB experience (group A, yes; group B, no). Surgical proficiency was defined as total operation time less than 65 minutes and cumulative radiation exposure time no more than 40 seconds. The learning curve was analyzed by cumulative summation (CUSUM) test. Clinical evaluations included Macnab classification, visual analog scale (VAS)-low back score, VAS-leg score, and Oswestry Disability Index (ODI). Follow-up information at 12 months was also obtained.

RESULTS

Integral number of cases before achieving an acceptable surgical level in group A (47.75 ± 2.50 cases) was significantly smaller than that in group B (56.50 ± 1.29 cases, p < 0.05), along with less accumulated failure (18.75 ± 0.96 cases vs. 25.50 ± 1.75 cases, p < 0.05). The two groups were comparable in clinical outcomes. Forty-seven cases of complications were observed, with 17 in group A and 30 in group B (p < 0.05).

CONCLUSION

Previous experience of SNRB improved the performance of PELD with shorter operation time and less radiation exposure. SNRB practice may reduce the complication rate without a significant effect on the recurrence of symptoms and reoperation.

Acetabular positioning is more consistent with the use of a novel miniature computer-assisted device

INTRODUCTION

Computer-assisted surgery (CAS) relying on registration of the anterior pelvic plane (APP) allows precise acetabular component placement. We determined the variability of cup placement in patients who underwent THA with and without the use of CAS that does not rely on the registration of APP.

METHODS

Fifty-one patients who underwent staged-bilateral THAs, one without CAS (control), and a subsequent one with CAS (study group), were included. Acetabular inclination and anteversion were measured on standardized post-operative radiographs. Variance in cup position and Lewinnek's zone proportionality were compared between the groups. Multiple regressions were performed to identify factors affecting variability in acetabular component placement.

RESULTS

The mean inclination for the control and study group was 42.7° (SD 4.5) and 42.5° (SD 2.9), respectively. The inclination variance was 20.5° and 8.2° respectively (p = < 0.001). Cup inclination was more consistent in the study than in the control group (deviation from the mean: 2.3° vs. 3.8°, p < 0.001). The mean anteversion for the control and the study group was 25.5° (SD 7.4) and 26.8° (SD 4.3), respectively. The anteversion variance was 54.2° and 18.2° respectively (p = <0.001). Consistency in cup anteversion was significantly improved with CAS (deviation from the mean: 3.4° vs. 5.8°; p = 0.002). Lewinnek's zone proportionality was not affected by the use of  CAS. In the linear regression analysis, CAS significantly increased consistency in cup inclination (p = 0.01). Patient's factors including BMI and laterality affected consistency of cup placement.

CONCLUSION

CAS without referencing the APP allows a more consistent orientation of the acetabular component when compared to freehand placement.

The what, when and how of orthopaedic registers: an introduction into register-based research

Establishment of orthopaedic registers started in 1975 and many registers have been initiated since. The main purpose of registers is to collect information on patients, implants and procedures in order to monitor and improve the outcome of the specific procedure.

Data validity reflects the quality of the registered data and consists of four major aspects: coverage of the register, registration completeness of procedures/patients, registration completeness of variables included in the register and accuracy of registered variables.

Survival analysis is often used in register studies to estimate the incidence of an outcome. The most commonly used survival analysis is the Kaplan–Meier survival curves, which present the proportion of patients who have not experienced the defined event (e.g. death or revision of a prosthesis) in relation to the time. Depending on the research question, competing events can be taken into account by using the cumulative incidence function. Cox regression analysis is used to compare survival data for different groups taking differences between groups into account.

When interpreting the results from observational register-based studies a number of factors including selection bias, information bias, chance and confounding have to be taken into account. In observational register-based studies selection bias is related to, for example, absence of complete follow-up of the patients, whereas information bias is related to, for example, misclassification of exposure (e.g. risk factor of interest) or/and outcome.

The REporting of studies Conducted using Observational Routinely-collected Data guidelines should be used for studies based on routinely-collected health data including orthopaedic registers.

Linkage between orthopaedic registers, other clinical quality databases and administrative health registers may be of value when performing orthopaedic register-based research.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180097

Learning Curve for Percutaneous Endoscopic Lumbar Diskectomy in Bi-needle Technique Using Cumulative Summation Test for Learning Curve

BACKGROUND

The purpose of this study was to determine the number of cases needed to achieve the level of competence for percutaneous endoscopic lumbar diskectomy (PELD) via the bi-needle technique using the cumulative summation test for learning curve (LC-CUSUM).

METHODS

A retrospective design was used. We included 60 patients who underwent a single-level PELD via the bi-needle technique performed by a single surgeon. The surgeon had 5 years of experience in open surgery including the transforaminal endoscopic spine system and Yeung endoscopic spine system but no experience in the bi-needle technique. Surgery success was defined as an operative time <60 minutes, and the acceptable procedure was completed within 3 times of C-arm fluoroscopies. The LC-CUSUM was used to analyze the data.

RESULTS

The average operative time for PELD via the bi-needle technique was 58.3 ± 12.4 minutes. The mean operative time was 65.7 ± 12.1 minutes in the early learning period (30 cases) and 51.0 ± 7.5 minutes in the late learning period (30 cases) (P < 0.05). On the basis of the evaluation indexes of the operative time and radioactive exposure, the LC-CUSUM signaled proficiency for the bi-needle technique at the 50th-54th operation. Seven cases of complications were observed during the whole learning process, with 6 in the early period and 1 in the late period (P < 0.05).

CONCLUSIONS

The novel bi-needle technique is safe and effective for PELD with appropriate patients, and the learning curve is acceptable. A substantial learning period (50-54 cases) is needed before a spine surgeon can master the bi-needle technique.

The Learning Curve for Biplane Medial Open Wedge High Tibial Osteotomy in 100 Consecutive Cases Assessed Using the Cumulative Summation Method

Purpose

The purpose of this study was to investigate whether surgical experience could improve surgical competency in medial open wedge high tibial osteotomy (MOWHTO).

Materials and Methods

One hundred consecutive cases of MOWHTO were performed with preoperative planning using the Miniaci method. Surgical errors were defined as under- or overcorrection, excessive posterior slope change, or the presence of a lateral hinge fracture. Each of these treatment failures was separately evaluated using the cumulative summation test for learning curve (LC-CUSUM).

Results

The LC-CUSUM showed competency in prevention of undercorrection, excessive posterior slope change, and lateral hinge fracture after 27, 47, and 42 procedures, respectively. However, the LC-CUSUM did not signal achievement of competency in prevention of overcorrection after 100 procedures. Furthermore, the failure rate for overcorrection showed an increasing tendency as surgical experience increased.

Conclusions

Surgical experience may improve the surgeon’s competency in prevention of undercorrection, excessive posterior slope change, and lateral hinge fracture. However, it may not help reduce the incidence of overcorrection even after performance of 100 cases of MOWHTO over a period of 6 years.

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.

A retrospective study on the relationship between altered native acetabular angle and vertical implant malpositioning

PURPOSE

Acetabular cup positioning in extreme angles of vertical position affects both stability and long-term survivorship of total hip arthroplasty. The purpose of this study is to determine whether native Sharp's angle is associated with an increased abduction angle of the acetabular component.

METHODS

Consecutive patients who underwent primary total hip replacement between February 2012 and August 2015 were included. Vertical positioning of acetabular implant in the antero-posterior post-operative radiographs were measured. The proportion of implants positioned outside the safe zone (40° ± 10°) was calculated and through a multivariate analysis, Sharp's angle and other factors possibly associated with cup malpositioning were evaluated.

RESULTS

Five hundred twenty-eight hip arthroplasties were analyzed. Prevalence of cup malpositioning was 7.6% and 25 patients had an altered native acetabular angle. An altered pre-operative Sharp's angle was associated with a higher risk of vertical malpositioning of the acetabular component (OR 2.51 IC 95%: 1.17-5.39) (p = 0.02). Body mass index, surgeon's volume, size of the implant, gender, pre-operative diagnose and age, were not associated with the position of the cup.

CONCLUSIONS

The alteration of the Sharp's angle as an indicator of hip dysplasia in native hips increases the odds of acetabular cup malpositioning. Other factors explored did not correlate with the position of the acetabular prosthesis. Systematic assessment of Sharp's angle should be included in the pre-operative planning of primary hip arthroplasty.

Value of the cumulative sum test for the assessment of a learning curve: Application to the introduction of patient-specific instrumentation for total knee arthroplasty in an academic department

BACKGROUND

The purpose of the study was to use the cumulative summation (CUSUM) test to assess the learning curve during the introduction of a new surgical technique (patient-specific instrumentation) in total knee arthroplasty (TKA) in an academic department.

METHODS

The first 50TKAs operated on at an academic department using patient-specific templates (PSTs) were scheduled to enter the study. All patients had a preoperative computed tomography scan evaluation to plan bone resections. The PSTs were positioned intraoperatively according to the best-fit technique and their three-dimensional orientation was recorded by a navigation system. The position of the femur and tibia PST was compared to the planned position for four items for each component: coronal and sagittal orientation, medial and lateral height of resection. Items were summarized to obtain knee, femur and tibia PST scores, respectively. These scores were plotted according to chronological order and included in a CUSUM analysis. The tested hypothesis was that the PST process for TKA was immediately under control after its introduction.

RESULTS

CUSUM test showed that positioning of the PST significantly differed from the target throughout the study. There was a significant difference between all scores and the maximal score. No case obtained the maximal score of eight points. The study was interrupted after 20 cases because of this negative evaluation.

CONCLUSION

The CUSUM test is effective in monitoring the learning curve when introducing a new surgical procedure. Introducing PST for TKA in an academic department may be associated with a long-lasting learning curve. The study was registered on the clinical.gov website (Identifier NCT02429245).

Level of surgical experience is associated with change in hip center of rotation following cementless total hip arthroplasty: A radiographic assessment

Objectives

After total hip arthroplasty (THA), restoration of hip center of rotation (COR) is essential to ensure stability of the prosthetic hip and longevity of the prosthesis. Our aim was to determine whether, and how, the COR changed postoperatively compared to the native COR following implantation of a cementless acetabular component in anatomical position and to compare the accuracy of cup placement between two surgeons with different levels of surgical experience.

Materials and methods

We evaluated 145 patients (145 hips) who underwent unilateral primary THA, who had no distorted acetabulum on the affected hip and a normal contralateral hip. Hip reconstruction was radiologically and clinically assessed at a minimum 2-year follow-up. Perioperative change in COR, initial cup position, offset, leg-length discrepancy (LLD), radiographic cup orientation, Harris Hip Score (HHS), component loosening, and dislocations were compared between the highly experienced surgeon and less-experienced surgeon groups.

Results

The COR was significantly displaced in the superior and medial directions postoperatively. Significant differences were identified in the vertical COR change, initial cup position, LLD, cup inclination, and cups within safe zones, but not in the horizontal COR change, offset parameters, cup anteversion, or HHS. There were no radiographic evidence of component loosening in both groups, but three dislocations (7%) only in the group operated on by the less-experienced surgeon (p = 0.027).

Conclusions

We found that the postoperative COR tended to be displaced in the superior and medial directions, and that the level of surgical experience strongly affected the accuracy and consistency of cup placement, particularly in COR position and cup inclination.

Does the Timing of Pre-Operative Medical Evaluation Influence Perioperative Total Hip Arthroplasty Outcomes?

Background:

Medical evaluation pre-operatively is an important component of risk stratification and potential risk optimization. However, the effect of timing prior to surgical intervention is not well-understood. We hypothesized that total hip arthroplasty (THA) patients seen in pre-operative evaluation closer to the date of surgery would experience better perioperative outcomes.

Methods:

We retrospectively reviewed 167 elective THA patients to study the relationship between the number of days between pre-operative evaluation (range, 0-80 days) and surgical intervention. Patients’ demographics, length of stay (LOS), ICU admission frequency, and rate of major complications were recorded.

Results:

When pre-operative evaluation carried out 4 days or less before the procedure date, there was a significant reduction in LOS (3.91 vs. 4.49; p=0.03). When pre-operative evaluation carried out 11 days or less prior to the procedure date, there was a four-fold decrease in rate of intensive care admission (p=0.04). Furthermore, the major complication rate also significantly reduced (p<0.05). However, when pre-operative evaluation took place 30 days or less before the procedure date compared to more than 30 days prior, there were no significant changes in the outcomes.

Conclusion:

From this study, pre-operative medical evaluation closer to the procedure date was correlated with improved selected peri-operative outcomes. However, further study on larger patient groups must be done to confirm this finding. More study is needed to define the effect on rare events like infection, and to analyze the subsets of THA patients with modifiable risk factors that may be time-dependent and need further time to optimization.

Training Performance in Diagnosis of Congenital Uterine Anomalies With 3-Dimensional Sonography: A Learning Curve Cumulative Summation Analysis

OBJECTIVES

We evaluated learning curve cumulative summation (CUSUM) of 3-dimensional (3D) sonography for diagnosis of congenital uterine anomalies and the deviations of the level of trainees' performance at the control-stage CUSUM.

METHODS

First-year (R1), second-year (R2), and third-year (R3) residents in obstetrics and gynecology received a training program to learn how to analyze 3D sonographic volumes and to classify congenital uterine anomalies. Each trainee worked on 155 3D sonographic volumes from preselected patients. Their results were evaluated by learning curve CUSUM and standard CUSUM. The time for each volume analysis was calculated for the expert examiner and the trainees.

RESULTS

Trainees R1, R2, and R3 reached competence at the 85th, 58th, and 40th evaluations, respectively, with success rates of 80%, 81%, and 85%, and kept the process under control with error levels of less than 4.5% until the end of the test. The trainees significantly reduced the average time of the evaluation per volume (P < .001).

CONCLUSIONS

Learning curve CUSUM provided quantitative indicators of the learning evolution of 3D sonography for diagnosis of congenital uterine anomalies by obstetrics and gynecology residents. The training received by the residents was adequate for diagnosis of congenital uterine anomalies using 3D sonography.

Learning Curves in Arthroplasty in Orthopedic Trainees

The NHS is adapting to a changing environment, in which economical constraints have forced theatres to maximise efficiency. An environment in which working hours and surgical exposure has been reduced and outcomes are being published. Litigation is high, and patients are living longer with higher demands. We ask, will traditional methods of apprentiship type training suffice in producing competent arthroplasty surgeons when hands on experience is falling. We review learning curves and assessment tools available to accurately assess competency and support trainee orthopaedic surgeons in their acquisition of surgical proficiency.

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.

Navigated Acetabular Cup Fixation for Acetabular Deformity or Revision Total Hip Arthroplasty

Purpose

To evaluate the usefulness of navigated acetabular cup fixation for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty.

Materials and Methods

This study enrolled 28 patients with at least 12 months' follow-up. The safe zone of the acetabular cup was defined as 40°±10°in inclination and 15°±10°in anteversion. The authors used the navigation and radiographic data to determine whether the acetabular cup was located within the safe zone or not. To evaluate the clinical outcomes, preoperative and last follow-up Harris hip scores were checked, and the occurrence of complications was evaluated.

Results

According to the navigation data, the mean inclination and anteversion were 38.5°±4.7°(range, 32°-50°) and 16.6°±4.0°(range, 8°-23°), respectively. According to the radiographic data the mean inclination and anteversion were 40.5°±4.6°(range, 32°-50°) and 19.4°±4.2°(range, 8°-25°), respectively. In both cases, all values were within the safe zone. Harris hip score was improved in all patients from preoperative 52.3±14.4 points (range, 29-87 points) to 88.0±9.0 points (range, 65-99 points) at the last follow-up. There was no dislocation or loosening of both cases.

Conclusion

Navigated acetabular cup fixation is a useful technique for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty because it prevents the malposition and related complications.