bluuebunny/crossref_metadata_2025 huggingface dataset:
A Retrospective Comparison of Functional Outcomes of Robotic-Assisted and Conventional Unicompartmental Knee Arthroplasty
Authors: Crizer Meredith , Battenberg Andrew , McGrath Mikayla , Kim Seong , Lonner Jess
Published: October 2019

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) is effective for alleviating symptoms of arthritis in a single knee compartment; however, errors in alignment and instability may predispose to failure. Robotic technology has improved precision, but its impact on functional recovery after UKA remains unknown. The purpose of this study was to compare early functional recovery, pain, and radiographic alignment in UKA performed with either robotic assistance or conventional methods.

METHODS: All consecutive patients undergoing UKA by a single physician from January 2015 to March 2018 were retrospectively reviewed. Lower Extremity Functional Scale (LEFS), KOOS Jr, and VAS (0-10) outcomes scores were collected preoperatively, 1, 6, and 12 weeks postoperatively. Radiographic alignment was assessed at the initial postoperative visit.

RESULTS: There were 161 patients, 65 conventional and 96 robotic. At baseline, there was no difference in average age, BMI, or outcomes scores between the two groups. Average preoperative pain was significantly higher in conventional patients (6.1 vs. 5.4; p=0.04). At 3 weeks post-op, conventional UKA patients still had significantly higher pain levels (3.9 vs. 3.1; p=.02). Both groups showed significant improvement in LEF (p<.0001) scores over time (p<.0001). Significant improvement in KOOS Jr. scores from pre-op (52.3) to 6 and 12-weeks postoperatively (67.6, 69.8; p<0.001). When comparing PCS of the VR/SF-12, the robotic-assisted group had significantly higher improvement compared to the conventional group at 6-weeks (40.6 vs. 35.6; p=0.02).

CONCLUSION: Robotic assisted UKA resulted in fewer radiographic outliers, and more rapid recovery with less early postoperative pain although functional differences tended to equilibrate by 3 months postoperatively.
Early Revision Analysis of Robotic-Arm Assisted and Manual Unicompartmental Knee Arthroplasty
Authors: Cool Christina , Needham Keith , Coppolecchia Andréa , Khlopas Anton , Sodhi Nipun , Ehiorobo Joseph , Mont Michael
Published: October 2019

Background:

The purpose of this study was to evaluate hospital admissions for revision surgeries associated with robotic-arm assisted unicompartmental knee arthroplasty (rUKA) vs. manual UKA (mUKA) procedures.

Methods:

Patients ≥18 years of age who received either a mUKA or a rUKA procedure were candidates for inclusion and were identified by the presence of appropriate billing codes. Procedures performed between March 1st, 2013 and July 31st, 2015 were used to calculate the rate of surgical revisions occurring within 24-months of the index procedure. Following propensity matching, 246 rUKA and 492 mUKA patients were included. Revision rates and the associated costs were compared between the two cohorts. The Mann-Whitney U test, was used to compare continuous variables, and fisher’s exact tests was used to analyze discrete categorical variables.

Results:

At 24-months following the primary UKA procedure, patients who underwent rUKA had fewer revision procedures (0.81% [2/246] vs. 5.28% [26/492]; p=0.002), shorter mean LOS (2.00 vs. 2.33 days; p>0.05), and incurred lower mean costs for the index stay plus revisions ($26,001 vs. $27,915; p>0.05) than mUKA patients. Length of stay at index, and index costs were also lower for rUKA patients (1.77 vs. 2.02 days; p=.0047) and ($25,786 vs. $26,307; p>0.05).

Conclusions:

Study results demonstrate that patients who underwent rUKA had fewer revision procedures, shorter LOS, and incurred lower mean costs (although not statistically different) during the index admission and at 24-months post-operative. These results could be important for payers as the prevalence of end-stage knee OA increases alongside the demand for cost-efficient treatments.
Radiographic and Clinical Outcomes in Total Hip Arthroplasty Utilizing a Porous Acetabular Shell Developed with Additive Manufacturing
Authors: Masini Michael , Levine Alana , Cruz Alice
Published: October 2019

This is a prospective data collection across seven centers in a non-randomized, post- market study where an additive manufactured cementless acetabular shell was used in primary total hip arthroplasty. There was a total of 254 hips/246 patients across seven centers. Clinical outcomes including all-cause survivorship, the Harris Hip Score (HHS), Lower Extremity Activity Scale (LEAS), Veterans Rand 12 (VR-12), EuroQol 5D (EQ- 5D) and radiographs were collected pre- and postoperatively. Radiographs were analyzed for presence of radiolucencies, migration and overall cup stability. All-cause survival rate was 99.61% and there were no reported radiolucencies greater than 2mm for any zone. There was a reduction in radiolucencies from the 6-week to 1-year postoperative timeframe. All cups reviewed at 1-year were stable with no radiolucencies in 96% of hips. These early results demonstrate the favorable properties of this shell and the use of additive manufacturing in orthopaedic surgery.
Multilevel Modeling of Resection Accuracy: Insights from 10,144 Clinical Cases using A Contemporary Computer-Assisted Total Knee Arthroplasty System
Authors: Dai Yifei , Bolch Charlotte , Jung Amaury , Hamad Cyril
Published: October 2019

This study applied an advanced statistical tool (multilevel modeling) to assess the accuracy of bony resection during total knee arthroplasty on 10144 cases performed using a modern CAOS system. An extensive list of factors was included for the modeling, including geographic region, inter-surgeon difference, surgeon’s adoption of the technology (learning or proficient phases), and historical progression of the CAOS application (software versions). The comprehensive analysis demonstrated that the CAOS system is an accurate and precise solution to assist the surgeons to achieve his/her surgical resection goals.
A Method for Validation and Error-Quantification of 3D-Printed Models for Acetabulum Fracture Surgery
Authors: Andress Sebastian , Achilles Felix , Suero Eduardo M. , Becker Christopher , Linhart Christoph , Greiner Axel , Rubenbauer Bianka , Kammerlander Christian , Boecker Wolfgang , Weidert Simon
Published: October 2019

Despite the increasing use of 3D printing in orthopedic surgery, there is no established method for the validation of a printed bone model. A printing error could potentially lead to complications, especially when the model is used for surgery planning. We aimed to validate a series of 33 acetabular fractures with a novel method by detailed analysis of model errors.

After applying a surface filter on both the patients model and the 3D printed model, a two-step registration consisting of landmark-based pre-registration and ICP-registration, was slightly varied and conducted 100 times, yielding a mean surface deviation and standard deviation for each model surface point.

We furthermore showed that more than 30 random ICP-registration points lead to a sufficiently good registration, and that the variation of the pre-registration is small enough to guarantee a stable ICP registration result.

Deviations caused by failed registration are unveiled by a large standard deviation of the 100 registration routines. For the fracture series, the mean surface deviation error between the printed model and the patient model was less than 1 mm (median = 0.7 mm; 95% CI = 0.68-0.72 mm). The largest errors were found in areas with remaining support structure material, on printbed-facing model sides and on abrasive surface regions. By visualizing the residual registration error, it was possible to clearly detect surface deviations and to quantify them.
Interesting Cases in Robotic-Arm Assisted Total Knee Arthroplasty
Authors: Garbarino Luke , Sodhi Nipun , Ehiorobo Joseph , Gold Peter , Marchand Kevin , Marchand Robert , Hepinstall Matthew , Mont Michael
Published: October 2019

Introduction:

Robotic-arm assisted surgery allows for the execution of well-aligned knee arthroplasty regardless of pre-existing deformity. This case series is presented to show the utility of robotic-arm assisted TKA in achieving well-balanced, well-aligned results in a variety of challenging scenarios.

Methods:

We present seven challenging cases of robotic-arm assisted total knee arthroplasty. There were two conversion TKAs following a previous surgery. One case featured a previous tibial plateau fracture treated with a plate and screws construct while another featured a prior femoral nail with significant bony overgrowth. Five cases of severe deformity were also identified, with one tibial nonunion, two valgus knees and one patient with two varus knees due psoriatic arthritis treated with staged bilateral TKAs. Patient clinical history, physical examinations, intraoperative surgical techniques and postoperative courses were recorded.

Results:

All cases were able to utilize effective preoperative planning to obtain precise intraoperative bone cuts and component positioning. Each of the seven cases achieved well-balanced, well-aligned arthroplasties. There were no intraoperative or postoperative complications. At latest follow up, all patients showed significant improvements in pain and ambulation compared to preoperative exams.

Discussion:

Robotic-arm assisted surgery allows for the integration of preoperative CT scans to establish and execute a surgical plan with precision. Despite the complexity of these cases, excellent results were achieved without the need for revision-type components. These cases display the ability of robotic-arm assisted surgery to achieve consistent well-aligned results with minimal bone loss in challenging total knee arthroplasty cases.
Patient-specific ROM and load-based Target Zone for Total Hip Arthroplasty and its Application in a retrospective Analysis
Authors: Habor Juliana , Fischer Maximilian C. M. , Tokunaga Kunihiko , Okamoto Masashi , Radermacher Klaus
Published: October 2019

The outcome of total hip arthroplasty (THA) depends on multiple alignment and design parameters. Unsuitable parameter settings could lead to impingement, dislocation, increased wear, and loosening. This work introduces a method for calculating a patient-specific target zone based on range of motion (ROM) related and load related criteria. Possible bone or prosthesis impingement are analyzed. The resulting hip force is calculated and compared to the pre-operative situation. The edge loading risk is analyzed. Pelvic tilt is considered for the calculation of the ROM and the load. THA parameters fulfilling all criteria are included in the target zone.

The above described method has been applied to 30 cases retrospectively. All cases had been planned and navigated on the basis of CT data. From each patient, pre- and post-operative CT and EOS data and Harris Scores were acquired. The pre-operative data served as the input data for the target zone calculator. We hypothesized that cases with post-operative THA parameters inside the target zones have higher scores than other cases.

The patients whose implants are within the target zones had higher scores than the remaining patients. Especially patients inside both target zones (combined target zone) had higher scores. The results also show that for 19 out of 30 patients, conventional CT-based planning and navigation does not provide optimal placement regarding the combined target zone. A further validation of the method with a larger sample size is part of our ongoing work.
Accuracy of Soft Tissue Balancing in Robotic-Assisted Measured-Resection TKA Using a Robotic Distraction Tool
Authors: Koenig Jan , Shalhoub Sami , Chen Eric , Plaskos Christopher
Published: October 2019

Achieving proper soft tissue balance during total knee arthroplasty (TKA) can reduce post- operative instability and stiffness as well as improve patient reported outcomes. The objective of this study was to compare final intra-operative coronal balance throughout the knee range of motion in navigated robotic-assisted TKA when performed with quantifiable feedback from a robotic ligament tensioning tool versus with standard trials and navigation measurements alone.

The study included a prospective cohort of 52 patients undergoing robotic-assisted TKA using a measured resection technique. The cohort was divided into two sequential groups: a non-sensor-assisted group (n=25) and a subsequent sensor-assisted group (n=27). Once bony cuts and soft tissue balancing was performed in the non-sensor cohort, the final tibiofemoral gaps were measured throughout the knee range of motion using a robotic-assisted tensioner with the surgeon blinded to the measurements. For the sensor cohort, the surgeon preformed soft-tissue releases or re-cuts in order to balance the knee using the gap measurement data from the robotic tensioner. The robotic-assisted tensioner was then used to measure the final medial and lateral gap measurements.

The average mediolateral gap difference throughout the range of flexion was 1.9 ± 0.7 mm with maximum difference of 7.8 mm for the non-sensor cohort. The sensor cohort had an average mediolateral difference of 1.5 ± 0.6 mm and a maximum difference of 3.8 mm. The difference between the two groups was statistically significant from 60 to 90 degrees of flexion. 38-41% of knees were balanced to within 1 mm mediolaterally in the non-sensor group compared to 48-70% for the sensor group when measured at various flexion angles. 65-76% of knees were balanced to within 2 mm for the non-sensor group compared to 78-86% for the sensor-assisted group. The number of knees requiring subsequent soft tissue releases was similar in each group. Soft tissue balancing with the aid of a robotic tensioning tool resulted in significantly more accurate soft tissue balance than when using navigation measurements and standard trials alone in this single surgeon study.
A 90-Day Episode-of-Care Cost Analysis of Robotic-Arm Assisted Total Knee Arthroplasty
Authors: Cool Christina , Jacofsky David , Seeger Kelly , Coppolecchia Andréa , Sodhi Nipun , Ehiorobo Joseph , Mont Michael
Published: October 2019

Introduction

One way to potentially help contain the rising healthcare costs is the utilization of technological advances, such as robotic-assistive technology, for total knee arthroplasty (TKA). Therefore, the purpose of this study was to perform a cost analysis between robotic-arm assisted TKA and manual TKA (mTKA) techniques. Specifically, we compared: 1) 90-day EOC costs, as well as several variables within the episode, including 2) index costs; 3) index lengths-of-stay (LOS); 4) discharge disposition; and 5) readmission rates.

Methods

A retrospective claims analysis was performed on Medicare FFS beneficiaries who underwent rTKA and mTKA procedures between January 1, 2016 and March 31, 2017. Patients were matched rTKA to mTKA in a 1-to-5 ratio, yielding 519 rTKAs and 2,595 mTKAs. The overall 90-day EOC costs, including the index procedures, LOS, discharge dispositions, and readmissions were compared between cohorts.

Results

Overall 90-day EOC costs ($18,568 vs. $20,960) as well as index facility costs ($12,384 vs. $13,024; p=0.0001) were found to be less than that for rTKA vs. mTKA. rTKA also accrued $1,744 fewer costs than mTKA (5,234 vs. $6,978; p=<0.0001) utilized fewer days in inpatient (4 vs. 7; p<0.0001) and SNF care (15 vs. 16; p=0.0642) as well as a 90-day readmission reduction of 33% (p=0.0423).

Discussion

The results from this study show rTKA to be associated with significantly lower 90-day EOC costs. These lower rTKA patient costs are likely attributable to the significantly lower index costs, increased likelihood of being discharged to home, shorter LOS, and decreased readmission rates, when compared to mTKA patient costs.
Clinical Use of a Computer Assisted Reverse Total Shoulder Arthroplasty System: an Analysis of 1702 Cases
Authors: Greene Alexander , Polakovic Sandrine , Roche Christopher , Dai Yifei
Published: October 2019

Placement of the glenoid component in reverse total shoulder arthroplasty (rTSA) is of paramount importance and can affect a patient’s range of motion postoperatively. Preoperative planning and computer assisted surgery (CAS) can improve upon glenoid placement, but such systems for rTSA have experienced limited commercial success. Postoperative surgical reports from the first 1702 clinical cases of a commercially available CAS rTSA system were collected and analyzed for implant selection, implant placement, and incision start to incision close operative time, and compared to similar date cohorts for non-navigated cases. Navigated rTSA cases had a significantly longer incision time than non-navigated cases. Augmented glenoid components were used in a much higher percentage of navigated cases than non-navigated cases, suggesting that augmented glenoid components provide utility for correcting pathologic glenoid wear. The average resultant version and inclination of the implanted component increased with the size of augment used, suggesting there may not be a clear consensus on optimal version or inclination. Long term clinical follow up will need to be collected to determine if preoperative planning combined with more precise and accurate glenoid component positioning leads to improved clinical outcomes and implant longevity.
Intra-Operative and Anatomic Verification of a TKA Computational Model for Pre-Operative Surgical Planning
Authors: Twiggs Joshua , Wakelin Edgar , Roe Justin , Fritsch Brett , Miles Brad
Published: October 2019

A promising measure of dynamic outcomes in Total Knee Arthroplasty (TKA) is the simulation of joint dynamics. These simulations are potentially useful for pre-operative planning, but are not yet validated for patient-specific variations in anatomy, which forms the aim of this paper. 284 patients from a database of total knee arthroplasty patients were analysed using a pre-operatively defined simulation predicting post-operative knee dynamics; each patient had previously undergone pre- and post-operative CT imaging and had been assessed using the Knee Injury and Osteoarthritis Outcome (KOOS) score at 6 months following surgery. A significant correlation was found between the simulated contact force and laxity in mid-flexion (r=-0.452, p<0.0001), and between the medio- lateral difference in contact force and difference in distal-vs-posterior femoral collateral ligament offset (r=-0.473, p<0.0001). A significant difference of 5 KOOS pain points (p=0.02) was found for patients with unusually low or high simulated contact force compared to normal. These results indicate the preoperative simulation is capable of distinguishing patient-specific kinematics prior to surgery, thereby demonstrating the utility of this simulation for making pre-surgical predictions of patient-specific kinematics and patient-reported outcomes.
Trends In Cup Position Utilizing Computer-Assisted Navigation During Total Hip Arthroplasty
Authors: Mays Rachel , Benson Jessica , Muir Jeffrey , White Peter , Meftah Morteza
Published: October 2019

Proper positioning of the acetabular cup deters dislocation after total hip arthroplasty (THA). The concept of a safe zone (SZ) for acetabular component placement was first characterized by Lewinnek et al. and furthered by Callanan et al. The SZ concept remains widely utilized and accepted in contemporary THA practice; however, components positioned in this SZ still dislocate. This study sought to characterize current mass trends in cup position identified across a large study sample of THA procedures completed by multiple surgeons. This retrospective, observational study reviewed acetabular cup position in 1,236 patients who underwent THA using computer-assisted navigation between July 2015 and November 2017. The overall mean cup position of all recorded cases was 21.8° (±7.7°, 95% CI = 6.7°, 36.9°) of anteversion and 40.9° (±6.5°, 95% CI = 28.1°, 53.7°) of inclination. For both anteversion and inclination, 65.5% (809/1236) of acetabular cup components were within the Lewinnek SZ and 58.4% (722/1236) were within the Callanan SZ. Acetabular cups were placed a mean of 6.8° of anteversion (posterior/lateral approach: 7.0°, anterior approach: 5.6°) higher than the Lewinnek and Callanan SZs whereas inclination was positioned 0.9° higher than the reported Lewinnek SZ and 3.4° higher than the Callanan SZ. Our data shows that while the majority of acetabular cups were placed within the traditional SZs, the mean anteversion orientation is considerably higher than those suggested by the Lewinnek and Callanan SZs. The implications of this observation warrant further investigation.
Predicting Functional Coronal Knee Laxity in Pre-Operative TKA Patients Using Morphological Measurements
Authors: Edwards Cerys , Moore Ella , Theodore Willy , Twiggs Joshua , Wakelin Edgar , Liu David , Miles Brad
Published: October 2019

Currently, pre-operative analysis of soft-tissue balance is limited to measures of passive laxity rather than active laxity. By including active laxity data, a more comprehensive surgical plan can be delivered, however there are no measures for active laxity currently in routine use. Therefore, the validation of a proxy measure based on routine collected imaging is valuable. This study aimed to determine whether coronal knee laxity can be predicted from pre-operative alignment and bony morphology of the knee. Fifty-eight patients with pre-operative CT and stressed x-ray imaging for activity laxity were analysed to identify anatomical landmarks and determine varus-valgus laxity ranges for a range of flexion angles with the joint subjected to lateral forces. Correlations between anatomical and alignment parameters, vs laxity ranges and midpoints were determined using pairwise complete Pearson linear correlation analyses. Of the 17 anatomical/alignment measurements studied, 8 correlated significantly with the knee laxity range’s midpoint at 20 ̊ flexion, with the strongest correlation being with supine coronal alignment (r = 0.95, p < 0.001); the findings were similar at 45-90 ̊. Compared to knee laxity midpoint, knee laxity range was not as strongly correlated with anatomical and alignment parameters, with only 3 anatomical parameters correlated significantly with laxity range at 20 ̊ flexion and none at 45-90 ̊ flexion. These results suggest morphological measurements and anatomical characteristics may help define functional coronal laxity range of the knee.
Clinical Use of a Computer Assisted Anatomic Total Shoulder Arthroplasty System: An Analysis of 574 Cases
Authors: Greene Alexander , Polakovic Sandrine , Roche Christopher , Dai Yifei
Published: October 2019

Accurate reproduction of glenohumeral anatomy during anatomic total shoulder arthroplasty (aTSA) has been shown to correlate with positive clinical outcomes. Preoperative planning and computer assisted surgery (CAS) can improve upon glenoid placement, but such systems for aTSA have experienced limited commercial success. Postoperative surgical reports from the first 574 clinical cases of a commercially available CAS aTSA system were collected and analyzed for implant selection, implant placement, and incision start to incision close operative time, and compared to similar date cohorts for non-navigated cases. Navigated aTSA cases had a significantly longer incision time than non-navigated cases. Augmented glenoid components were used in a much higher percentage of navigated cases than non-navigated cases, suggesting that augmented glenoid components provide utility for correcting pathologic glenoid wear. The average resultant version of the implanted component increased with the size of augment used, suggesting there may not be a clear consensus on optimal retroversion. term clinical follow up will need to be collected to determine if preoperative planning combined with more precise and accurate glenoid component positioning leads to improved clinical outcomes and implant longevity.
In-Hospital manufacturing of patient specific 3D-printed guides
Authors: Aguado-Maestro Ignacio , García-Cepeda Ignacio , González-Álvarez Juan José , Cebrián-Rodríguez Elisa , López-Sánchez Javier , Fernández-Díez Diego , Sierra-Matilla Leandro , García-Alonso Manuel
Published: October 2019

Introduction

Patient specific instrumentation is a novel aid the industry has been implementing in our hospitals during the last years. However, the cost of the process and the impossibility to discuss face to face with the manufacturer the needs of the particular cases may favor the in-hospital production of these devices.

We present the design and manufacturing process of three patient-specific devices to treat complex common situations in orthopaedic surgery, such as intramedular tumor resections, long bone pseudarthrosis and malunions of articular fractures.

Material and Methods

CT scans of the region of interest were performed to all the patients. Horos® software was used to isolate the affected bone region, whereas Meshmixer® software was used to create the patient specific guides. An Ultimaker 2+® 3D printer was used to print the guide, in a biocompatible material (SmartFil® Medical). The printing parameters included a nozzle of 0.6 mm and a layer height of 0.1 mm.

There was one case of a low-grade chondrosarcoma in which we created a guide to resect enough cortical bone to make an extended curettage of the lesion. Phenol and PMMA were used as adjuvants after the curettage. We used the same guide to obtain an exact replica of allograft which was later placed in position.

We had a femur diaphyseal atrophic pseudarthrosis in a patient with achondroplasia, in which the guide permitted the resection of the affected bone with a saw and posterior osteosynthesis with an anterior LCP plate.

Finally, in an intraarticular malunion of a distal radius Die-Punch fracture we used the guide to make an osteotomy of the affected articular portion and correct the articular surface. Bone autograft was added prior to the osteosynthesis with a plate.

Results

Mean design time was 6.3 hours. Mean printing time was 5.2 hours. The price of the filament used for each guide was under 10 USD. The mean time from the CT-Scan and the surgery being performed was 2.7 months. In all cases the patient specific guides fitted in the bone and permitted the planned resection/osteotomy.

All the surgeries fulfilled their purpose.

Conclusions

Patient specific guides are easy to design in a local setting with the aid of free software. Design time still needs dedication although it permits the manufacturing of the guides following surgeon needs. The use of self-designed and printed guides is safe and accurate, with a low cost for the institutions.
Mid-term Patient Reported Outcomes and Survivorship Following Robotic Assisted Total Knee Replacement: A Cohort Study
Authors: Chen Eric , Husain Adil , Billow Nicholas , Koenig Jan , Plaskos Christopher
Published: October 2019

Despite the advantages of real time alignment assessment and visual feedback while balancing offered by robotic assisted total knee arthroplasty, few clinical studies have reported patient outcomes. The purpose of this study is to report the midterm patient reported outcomes and survivorship of a computer-navigated TKA system with a robotic cutting guide. This patient cohort is the first IRB approved series of patients treated in the United States with this robotic knee system. This study serves as a midterm follow-up study on for this cohort, upon which learning curve, intra-operative efficiency, and deformity management were previously reported

Recipients of 152 consecutive total knee arthroplasties using a computer- navigated TKA system performed by a single surgeon between June 2010 and January 2012 were surveyed between 5-7 years post-operatively. 94 patients were reachable for outcome measures and survivorship data was obtained in 98 patients. Mean patient age at follow up was 74.6 +/- 8.6 years. Implant survivorship was 99.0% at an average of 6.5 years. Mean patient reported knee outcome scores were 62.7 (KSS-SF) and 79.5 (KOOS-JR). Overall satisfaction rate was reported as “satisfied or very satisfied” in 80.2%, “neutral” in 11.0%, and “dissatisfied or very dissatisfied” in 7.7% of patients.

Robotic assisted total knee arthroplasty using a computer-navigated TKA system with a robotic cutting guide appears to provide a durable outcome with sustainable midterm patient reported outcomes and excellent survivorship. Further follow up is required to determine if there are long term outcome and survivorship benefits of robotic assisted total knee arthroplasty.
Automatic analysis of morphological parameters of the patella based on three-dimensional (3D) surface data
Authors: Asseln Malte , Radermacher Klaus
Published: October 2019

Morphological knowledge about the patella is fundamental to understand normal and pathological knee joint mechanics and guide the design of patellar prosthesis. In literature there are a large number of parameters and measurement methods described to characterize the patellar morphology. However, the majority rely on manual measurements, sample sizes are often small and the number of morphological parameters is limited. The goal of this study was to identify morphological parameters of the patella, develop a standardized and fully automatic workflow for their extraction, and to provide accurate statistical numbers for a large number of patients.

An anonymized dataset of 412 knee geometries from consecutively scheduled total knee arthroplasty patients (gender: 248 female, 164 male) were available. A total number of 8 morphological parameters were identified and later used for the calculation of 3 additional aspect ratios. A fully automatic workflow was developed for parameter extraction based on the three-dimensional surface data. The workflow was applied to all datasets and the results were stored in a database for statistical analysis.

The workflow could process all 412 patellar geometries fully automatic without any algorithmic adjustment or user interaction. The processing time was in the range of 30 s per case. The results of the statistical analysis were in very good agreement with the literature. The numbers clearly demonstrated gender-specific differences, however, it is still unknown whether these are sexual dimorphism or can be eliminated by a scaling. Extensive statistical analysis on gender-specific differences and their normalization is part of future work.
Proximal Femoral Asymmetry in Japanese Patients before Total Hip Arthroplasty
Authors: Fischer Maximilian C. M. , Tokunaga Kunihiko , Okamoto Masashi , Radermacher Klaus
Published: October 2019

Templating is an important and established step in the preoperative planning process of total hip arthroplasty (THA) in order to select the size and position of the implant. In severely arthritic cases, the unaffected contralateral side is sometimes used as a reference to reconstruct morphological parameters of the planned implantation (ipsilateral) side, for example the femoral offset, the leg length or the antetorsion. Recent studies have shown that a significant side-to-side asymmetry of important proximal femoral parameters already exists in healthy subjects questioning the validity of the contralateral side as a reference. However, if preoperative asymmetry is larger than asymmetry in healthy subjects, preoperative planning can still make use of the contralateral side to target a postoperative result within the range of physiological asymmetry. Therefore, the specific objective of this study was to quantify the preoperative side-to-side asymmetry of five important morphological parameters of the proximal femur. Significant side-to- side differences between the ipsilateral side and the contralateral side were detected for the antetorsion, the offset, the neck length and the femoral length. The antetorsion is significantly higher for the ipsilateral side whereas offset, neck length and femoral length are significantly smaller. Mean and maximum difference in antetorsion is almost twice as high for the THA patients in comparison to healthy subjects. The same trend can be observed for the femoral length, less pronounced also for the caput-collum-diaphyseal angle. The comparison of proximal femoral side-to-side differences for subjects before THA and healthy subjects leads to the conclusion that contralateral templating can be a reasonable basis for THA planning of severely arthritic hips if the contralateral side shows no signs of osteoarthritis or developmental dysplasia.
1-Year Patient Outcomes for Robotic-Arm Assisted vs. Manual Total Knee Arthroplasty
Authors: Marchand Robert , Sodhi Nipun , Anis Hiba , Ehiorobo Joseph , Newman Jared , Marchand Kevin , Taylor Kelly , Condrey Caitlin , Hepinstall Matthew , Mont Michael
Published: October 2019

Introduction:

Robotic-arm assisted (RAA) total knee arthroplasty (TKA) has been shown to potentially have certain pre- and intra-operative advantages over manual techniques. Although there are many studies on the alignment advantages when using the robotic-arm assisted (RAA) system for total knee arthroplasty (TKA), there have been questions regarding patient-reported outcomes. Therefore, the purpose of this study was to use this index to compare: 1) total; 2) physical function; and 3) pain scores for manual vs. RAA patients.

Methods:

We compared 53 consecutive robotic-arm assisted to 53 consecutive manual TKAs. No differences in pre-operative scores were found between the cohorts. Patients were administered a modified WOMAC satisfaction survey pre-operatively, and at 1-year post-operatively. Univariate analyses and multivariate models with stepwise backward linear regression were utilized to evaluate the associations between outcome scores and surgical technique, age, sex, as well as body mass index (BMI).

Results:

The RAA cohort had significantly improved mean total (6±6 vs. 9±8 points, p=0.03) and physical function scores (4±4 vs. 6±5 points, p=0.02) when compared to the manual cohort. The mean pain score for the RAA cohort [2±3 points (range, 0 to 14 points)], was also lower than that for the manual cohort [3±4 points (range, 0 to 11 points) (p=0.06)].

On backward linear regression analyses, RAA was found to be significantly associated with more improved total (beta coefficient [β]-0.208, SE [standard error] 1.401, p<0.05), function (β=0.216, SE=0.829, p<0.05), and pain scores (β-0.181, SE=0.623, p=0.063). The RAA technique was found to have the strongest association with improved scores.

Conclusion:

With newer surgical technologies constantly being introduced, it is imperative to continue to evaluate these new modalities, particularly in their abilities to improve patient satisfaction outcomes. This study suggests that RAA patients may have short term improvements at minimum 1-year post-operative. However, longer-term follow up with greater sample sizes are needed to further validate these findings.
The Best Bone of Acetabulum for Cup Component Placement in Total Hip Arthroplasty in Patients with Crowe Type I-III Dysplastic Hips: a Computer Simulation Study
Authors: Zheng Linli , Lin Yangyang , Zhang Xiaoyan , Ling Qianhui , Liao Weiming , Wu Peihui
Published: October 2019

For cup implantation in dysplastic acetabulum, the vertical height of the cup center (V-HCC) should be carefully and precisely controlled in order to achieve sufficient host bone-cup coverage (BCC), but excessively superior placement of the cup should be avoided. Using computer software, pelvis models were separately reconstructed in 51 patients (61 hips) with severe osteoarthritis secondary to Crowe type I-III hips. Acetabular height and doom thickness were measured on the mid-acetabular coronal cross section. V-HCC was defined as the vertical distance from the cup center to the interteardrop line (ITL). In the cup implantation simulation, the cup was placed at the initial preset position, with a V-HCC of 15 mm, and moved proximally by 3-mm increments. At each level, the BCC was automatically calculated by computer. There were no significant between-group differences in maximum thickness of the acetabular doom; however peak bone stock values were obtained at heights of 41.63 mm ± 5.14 mm (Crowe type I), 47.58 mm ± 4.10 mm (Crowe type II), and 55.78 mm ± 3.64 mm (Crowe type III) above the ITL. At 15 mm of HCC, BCC was 79%±7% (Crowe type I), 74%±9% (Crowe type II), and 61%±6% (Crowe type III). In order to achieve 80% of the BCC, the evaluation distance was 1.33 ± 1.62 mm (95% CI 0.67–2.01), 3.32 ± 2.94 mm (95% CI 1.94–4.69), and 9.68 ± 3.91 mm (95% CI 7.60–11.77) for Crowe type I, II, and III hips, respectively. Acetabular bone stock for cup placement correlates with the degree of hip dysplasia in patients. During acetabular reconstruction in Crowe type I, II, or III hips, slightly superior placements, <25 mm from the ITL, retained sufficient bone coverage.
3D extended field-of-view of the knee joint bones using ultrasound: Application in orthopaedics
Authors: Nasan Maged , Morvan Yannick , Dardenne Guillaume , Chaoui Jean , Stindel Eric
Published: October 2019

Patient Specific Instruments (PSIs) have been introduced into the surgical workflow as a modern way to assist the surgeon in performing femur and tibia resection in Total Knee Arthroplasty (TKA). These PSIs are based on an accurate reconstruction of the surface of the knee’s bones.

In this work, we propose two 3D-3D image-based registration methods to reconstruct an extended field-of-view of the knee joint using only a motorized ultrasound transducer. Those methods are: (1) a dense voxel-based registration method, which needs to preprocess the ultrasound images and form an ultrasound volume. Then, computing the Mutual Information (MI) for each relative displacement to align every pair of volumes, (2) a sparse point-based registration method, which takes into account the point set located on the surface of the bone in ultrasound images. This method detects bony features using ORB detector and matches the corresponding points to find the best transformation using Coherent Point Drift (CPD).

The preliminary qualitative results performed in vitro show that from a set of consecutive ultrasound volumes, an extended field-of-view can be reconstructed using only ultrasound images without any external trackers. Results of the voxel-based approach show that MI is more robust against noise comparing to other similarity measures. On the other hand, results of point-based approach show that is much faster in computation with a low false-positive rate compared to other feature-detectors like SIFT and SURF. Furthermore, experiments show that CPD is less affected by noisy data compared to the classical ICP, which is promising to continue evaluating our work in vivo.
Automatic standardized shape analysis of the sagittal profiles (J-Curves) of the femoral condyles based on three-dimensional (3D) surface data
Authors: Asseln Malte , Fischer Maximilian C. M. , Chan Hao Yang , Meere Patrick , Walker Peter , Radermacher Klaus
Published: October 2019

The sagittal geometry of the articular surfaces of the femoral condyles, also called J-Curves because of the letter J-shaped profiles, is one of the main factors affecting knee kinematics in the normal knee

[1] as well as artificial knee [2]. For example, Clary et al. [2] showed that large changes in the J-curves’ radii cause abrupt changes in the center of rotation, leading to decreased anterior-posterior stability. In literature, the sagittal profile has been described mathematically by different geometric figures, such as arcs, circles, involutes of a circle, and Archimedean and logarithmic spirals [3]. The circular approximation has been often followed in the different concepts of knee implant designs, such as single- radius-, dual-radius-, or multiple-radius-designs. Single-radius-designs have a fixed flexion-extension axis. Dual-radius-designs consist of a larger distal and smaller posterior radius aiming a higher congruence during low flexion (high loading) and lower congruence at high flexion angles (high mobility). Multi-radius-designs try to mimic a physiological roll-glide ratio. However, the description of these circles is usually not standardized. A summary of different measurement methods was given by Nuno and Ahmed [4].

Thereby, the radii are very sensitive regarding the length of the fitting arc [5] and position of the sagittal plane [3]. Nuno and Ahmed [3] found that medial and lateral condyles can be adequately described by two-circular arcs and proposed a quantitative description. However, the posterior limits of their arcs were not considered individually, the anterior limits were defined based on soft-tissue measurements (anterior margins of the menisci), and the sagittal plane was positioned at the posterior extreme points, which might be inadequate in arthritic knees.

The goal of this study was to automatically analyse the medial and lateral sagittal profiles of the femoral condyles mathematically by two-circular arcs in a standardized and robust fashion.
Robotic use improves post-resection bone cuts during total knee arthroplasty
Authors: Scholl Laura , Hampp Emily , Alipit Vincent , Mont Michael , Bhave Anil , Chen Antonia
Published: October 2019

The purposes of this study were to assess 1) number of bone recuts with manual TKA (MTKA) vs RATKA and 2) influence of robotics on surgeon’s posture and workload during recutting.

Two surgeons each performed three MTKAs and three RATKAs. Occurrence, time and type of post-resection recuts were recorded. Movement sensors were placed on surgeons to measure lower back, shoulder, and cervical movements. Data was analyzed for average angle, percent of time in high-risk range of motion (ROM), number of times in high-risk sustained positions, and repetitions per minute. Surgeons were surveyed to assess physical and mental effort on a 1-10 scale (1 as lowest effort).

Six TKAs required recuts, five MTKA and one RATKA. 5 were on tibia and 1 (MTKA) was on femur. Compared to RATKA, MTKA had: increased time to perform recut (4.8-minutes vs. 3.7-minutes), increased occiput and T3 (38.9 vs 17.0° and 16.0 vs 3.0°) average angles, increased lower back ROM, sustained positions, and repetitions (14 vs 0%, 1 vs 0, and 1.9 vs 0), increased non-dominant shoulder ROM and repetitions (22 vs 0% and 2 vs 1), reduced dominant shoulder ROM (56 vs 19%), increased mental (4.2 vs 2.8) efforts and increased physical (3.3 vs 1.7) efforts.

Results indicate RATKA may reduce incidence of post-resection bone recuts. Increased time and required efforts for MTKA may be due to setting up surgical cutting instruments. Whereas, for RATKA, recut changes are made on the robotic surgical screen and the robotic-arm is used to help perform the recut.
Combined pre-operative planning and intra-operative navigation to precisely restore patient-specific anatomy in total hip replacement procedures
Authors: Wahrburg Jürgen , Gieseler Oliver , Roth Hubert
Published: October 2019

The paper presents an approach for computer-assisted implantation of artificial hip joints. It is based on a novel solution combining pre-operative planning and intra- operative navigation in a way that the natural anatomy of the joint before surgery can be restored as close as possible, or with exactly planned modifications. A surgical workflow has been developed which highly focusses on the registration and restoration of patient specific parameters instead of using generalized criteria like the Lewinnek safe zone. The feasibility of the approach has successfully been demonstrated by a laboratory setup of Sawbone models.
Robotic Assisted Total Knee Arthroplasty in Presence of Extra-Articular Deformity
Authors: Sodhi Nipun , Khlopas Anton , Ehiorobo Joseph , Condrey Caitlin , Marchand Robert , Hepinstall Matthew , Mont Michael
Published: October 2019

Introduction:

There is a lack of data concerning the use of the robotic device for patients with other potentially complex surgical factors. Therefore, the purpose of this series was to present cases in which the robotic-arm assisted TKA (RATKA) application was used in the setting of extra-articular deformities to educate the surgeon community on this potentially useful method to address these complex cases.

Methods:

Three cases of patients who underwent RATKA in the setting of pre-operative extra-articular deformities were identified. One had femoral and tibial fracture malunion, another had proximal tibial fracture nonunion, and another with a healed tibial plateau fracture. Patient clinical histories, intra-operative surgical techniques, and post-operative outcomes were obtained. Specific focus was placed on the surgical management of the patient’s pre-existing deformity.

Results:

The robotic software was able to appropriately consider the extra-articular deformity in the pre-operative and real-time updated intra-operative plans. Doing so, the surgeon achieved a balanced and aligned TKA. No intra-operative or post-operative complications occurred. Antero-posterior and lateral radiographs demonstrated well fixed and aligned femoral and tibial components with no signs of loosening or osteolysis. On physical exam, all patients had excellent range of motion with mean flexion of 122 degrees (range: 120 to 125 degrees of flexion) at final follow-up.

Discussion:

Utilizing pre-operative CT-scans with a 3D plan for robotic-arm assisted surgery allowed for appropriate assessment of the deformity pre-operatively and execution of a plan for a balanced and aligned total knee arthroplasty. We have demonstrated excellent results utilizing robotic-arm assisted TKA in these complex cases.
Less Iatrogenic Soft Tissue Damage Utilizing Robotic Assisted Total Knee Arthroplasty when Compared with a Manual Approach: A Blinded Assessment
Authors: Hampp Emily , Sodhi Nipun , Scholl Laura , Deren Matthew , Yenna Zachary , Westrich Geoffrey , Mont Michael
Published: October 2019

While manual total knee arthroplasty (MTKA) has demonstrated excellent clinical results, occasionally intraoperative damage to soft tissues can occur. Robotic-arm assisted technology is designed to constrain a sawblade in a haptic zone to help ensure that only the desired bone cuts are made. The objective of this cadaver study was to quantify the extent of soft tissue damage sustained during TKA through a robotic-arm assisted (RATKA) haptically guided approach and conventional MTKA approach. Four surgeons each prepared 3 RATKA and 3 MTKA specimens for cruciate retaining TKAs. RATKA was performed on one knee, with MTKA on the other. Postoperatively, 2 additional blinded surgeons, assessed and graded damage to 14 key anatomic structures. A Kruskal-Wallis hypothesis test was performed to assess for statistical differences of soft tissue damages between RATKA and MTKA cases. A p-value <0.05 was used as the threshold for statistical significance, and p-values were adjusted for ties. Significantly less damage occurred to the PCL in the RATKA than the MTKA specimens (p<0.0001). RATKA specimens had less damage to the dMCL (p=.149), ITB (p=0.580), popliteus (p=0.248), and patellar ligament (p=0.317). The results of this study indicate that RATKA may result in less soft-tissue damage than MTKA, especially to the PCL.