Intraoperative computer-assisted prediction of intraarticular contact pressures in the knee during high tibial osteotomy.

OBJECTIVES: To develop an accurate intraoperative method to estimate changes in intraarticular contact pressures during high tibial osteotomy (HTO). METHODS: Changes in knee alignment and pressure were monitored in real time in seven cadaver specimens that received HTO. Intraarticular contact pressure (N/mm2 ) in each knee compartment was estimated based on extraarticularly acquired data (leg alignment, correction, and ankle tilt) and based on the application of an axial force of half bodyweight (400-450 N). RESULTS: Contact pressure estimation was more accurate in the lateral compartment (R2  = 0.940) than in the medial compartment of the knee (R2  = 0.835). The optimism-corrected R2 was 0.936 for the lateral compartment and 0.821 for the medial compartment. CONCLUSIONS: We have established a framework for estimating the change in intraarticular contact pressures based on extraarticular data. This research could be helpful in generating appropriate algorithms to estimate joint alignment changes based on applied loads.

Comparison of algorithms for automated femur fracture reduction.

PURPOSE: We designed an experiment to determine the comparative effectiveness of computer algorithms for performing automated long bone fracture reduction. METHODS: Automated reduction of 10 3D fracture models was performed using two computer algorithms, random sample matching (RANSAM) and Z-buffering (Z-Buffer), and one of five options of post-processing: none; iterative closest point algorithm (ICP); ICP-X1; ICP-X2; and ICP-X3. We measured the final alignment between the two fragments for each algorithm and post-processing option. RESULTS: The RANSAM algorithm combined with postprocessing algorithm ICP-X1 or ICP-X3 resulted in the most accurate fracture reduction in the translational plane. No discernible difference was observed in the rotational plane. Automated reduction had more accurate translational displacement than telemanipulated manual reductions. CONCLUSION: This study supports the use of the RANSAM algorithm for automated fracture reduction procedures. The use of ICP algorithms provides further optimization of the initial reduction.

Improving the human-robot interface for telemanipulated robotic long bone fracture reduction: Joystick device vs. haptic manipulator.

OBJECTIVES: Intramedullary nailing is the treatment of choice for femoral shaft fractures. However, there are several problems associated with the technique, e.g. high radiation exposure and rotational malalignment. Experimental robotic assistance has been introduced to improve the quality of the reduction and to reduce the incidence of rotational malalignment. In the current study, we compare two devices for control of the fracture fragments during telemanipulated reduction. METHODS: Ten male and ten female subjects were asked to participate as examiners in this experiment. A computer program was developed to render and manipulate CT-based renderings of femur fracture bone fragments. The user could manipulate the fragments using either a simple joystick device or a haptic manipulator. Each examiner performed telemanipulated reduction of 10 virtual fracture models of varying difficulty with each device (five in a 'training phase' and five in a 'testing phase'). Mixed models were used to test whether using the haptic device improved alignment accuracy and improved reduction times compared to using a joystick. RESULTS: Reduction accuracy was not significantly different between devices in either the training phase or the testing phase (P > 0.05). Reduction time was significantly higher for the Phantom device than for the Joystick in the training phase (P < 0.0001), but it was no different in the testing phase (P = 0.865). High spatial ability with electronics had a significant effect on the alignment of fracture reduction and time to reduction. CONCLUSIONS: The Joystick and the Phantom devices resulted in similarly accurate reductions, with the Joystick having an easier learning curve. The Phantom device offered no advantage over the Joystick for fracture telemanipulation. Considering the high cost of the Phantom device and the lack of a demonstrable advantage over the Joystick, its use is not justified for implementation in a fracture telemanipulation workflow. The Joystick remains as a low-cost and effective device for developing 3D fracture telemanipulation techniques.

Robotic technique improves entry point alignment for intramedullary nailing of femur fractures compared to the conventional technique: a cadaveric study.

We aimed to test whether a robotic technique would offer more accurate access to the proximal femoral medullary cavity for insertion of an intramedullary nail compared to the conventional manual technique. The medullary cavity of ten femur specimens was accessed in a conventional fashion using fluoroscopic control. In ten additional femur specimens, ISO-C 3D scans were obtained and a computer program calculated the ideal location of the cavity opening based on the trajectory of the medullary canal. In both techniques, the surgeon opened the cavity using a drill and inserted a radiopaque tube that matched the diameter of the cavity. The mean difference in angle between the proximal opening and the medullary canal in the shaft of the femur was calculated for both groups. Robotic cavity opening was more accurate than the manual technique, with a mean difference in trajectory between the proximal opening and the shaft canal of 2.0° (95% CI 0.6°-3.5°) compared to a mean difference of 4.3° (95% CI 2.11°-6.48°) using the manual technique (P = 0.0218). The robotic technique was more accurate than the manual procedure for identifying the optimal location for opening the medullary canal for insertion of an intramedullary nail. Additional advantages may include a reduction in total radiation exposure, as only one ISO-C 3D scan is needed, as opposed to multiple radiographs when using the manual technique.

Repeatability and reproducibility of a telemanipulated fracture reduction system.

We evaluate the inter- and intraobserver variability of a telemanipulated femur fracture reduction system using a joystick device. Five examiners performed virtual reduction of 3D femur fracture models on two separate occasions. We assessed the inter- and intraobserver variability for the final alignment and reduction. The average difference between testing rounds was only 0.3 mm for overall displacement and 0.5° for overall rotation. There was an average time reduction between rounds of 11.7 s. The mean differences in overall displacement between examiners ranged between 0.2 and 0.9 mm; between 0.2° and 3.2° for overall rotation; and between 9 and 82 s for time to reduction. The time required to complete the reduction did not have a significant effect on the overall displacement or rotation of the final model. Telemanipulated fracture reduction is a reliable and reproducible technique, which does not require extensive training.

Robotic guided waterjet cutting technique for high tibial dome osteotomy: A pilot study.

BACKGROUND: Oscillating saws generate high levels of heat (up to 150°C), which can lead to tissue necrosis, delayed healing and infection. Abrasive waterjet-cutting techniques have been described as a new tool to perform bone cuts, with less heat generation. METHODS: Four lower-limbs of four human alcohol conserved cadavers were tested. Navigation references were attached to the tibia and an intraoperative fluoroscopy-based 3D scan was obtained. A 1.2 mm diameter nozzle was attached to a robotic arm, which was guided to follow a pre-specified path. In addition, a self-designed jet-absorber was applied to protect the posterior neurovascular structures. Magnesium was added as an abrasive substance to improve the cutting ability of the waterjet. RESULTS: In all four cadavers, the osteotomies could be carried out as planned, resulting in smooth cut surfaces. No damage to the soft-tissues was observed. CONCLUSIONS: The advantages of abrasive waterjet-cutting give it great potential in orthopaedic surgery. A current disadvantage is the amount of magnesium solute that is left on the surgical field and can be harmful to the patient.

Robotic distal locking of intramedullary nailing: Technical description and cadaveric testing.

Interlocked intramedullary nailing is the treatment of choice for femoral shaft fractures. However, distal locking is a technically challenging part of the procedure that can result in distal femoral malrotation and high radiation exposure. We have tested a robotic procedure for robotic distal locking based on the computation of a drilling trajectory on two calibrated fluoroscopic images. Twenty distal holes were attempted in ten cadaveric femur specimens. Successful screw hole drilling was achieved at the first attempt in each of the ten specimens (20 drill holes in total). No failures were recorded. The average total number of images needed was 6.5 +/- 3.6. The average computation time was 16.5+/- 16.0 seconds. Robotic distal locking was feasible in this test and can be integrated into a fully robotic intramedullary nailing procedure.

Femoral malrotation after surgical treatment of femoral shaft fractures in children: a retrospective CT-based analysis.

BACKGROUND: Rotational malalignment is an important and not always avoidable complication after surgical treatment of femoral shaft fractures. The purpose of this study was to determine the incidence of rotational malalignment in children after surgical treatment of femoral shaft fractures and to identify potential patient- and treatment-related risk factors based on data obtained from CT scans. METHODS: We conducted a retrospective analysis of all patients aged less than 15 years with femoral shaft fractures admitted to our level 1 trauma centre between January 2004 and July 2014. Patients having obtained postoperative CT scans were included for the determination of rotational malalignment. A difference of greater than 15° in femoral torsion between both legs was considered as clinically relevant. Additionally, demographic data and clinical information such as fracture type, treatment method, fluoroscopy time and operating time were reviewed. RESULTS: A total of 24 patients were enrolled in this study. Clinically relevant femoral malrotation was identified in 10 patients (41.6%). Surgical revision was performed in 7 patients (29.2%). There was no association between the type of surgical procedure, age and the incidence and/or amount of femoral malrotation. CONCLUSIONS: The data suggest that relevant femoral malrotation is an evident problem after surgical treatment of femoral shaft fractures in children that requires critical postoperative assessment. LEVEL OF EVIDENCE: Level III, retrospective study.

The effect of distal tibial rotation during high tibial osteotomy on the contact pressures in the knee and ankle joints.

PURPOSE: Intraoperative fracture of the lateral cortex fractures of the tibia is a potential complication of high tibial osteotomy (HTO), which may result in inadequate rotational alignment of the distal tibia. Our aim was to determine how rotational malalignment of the distal tibial segment distal would affect intraarticular contact pressure distribution in the knee and ankle joints. METHODS: A medial, L-shaped opening-wedge HTO was performed on seven human lower body specimens. A stainless steel device with integrated load cell was used to axially load the leg. Pressure-sensitive sensors were used to measure intraarticular contact pressures. Intraoperative changes in alignment were monitored in real time using computer navigation. Measurements were performed in the native knee alignment, after 10° and 15° of alignment correction and with the distal tibia fixed at 15° of external rotation. RESULTS: Moderate-to-large alignment changes after medial opening-wedge HTO resulted in a shift in intraarticular contact pressures from the medial compartment of the knee towards the lateral compartment. However, fixation of the distal tibial segment at 15° of external rotation neutralized this intended beneficial effect. In the ankle, external rotation of the distal tibia also caused a reduction in contact pressures and tibiotalar contact area. CONCLUSION: Malrotation of the distal tibial fragment negates the intended effect of offloading the diseased compartment of the knee, with the contact pressures remaining similar to those of the native knee. Furthermore, malrotation leads to abnormal ankle contact pressures. Care should be taken to ensure appropriate rotational alignment of the distal tibial segment during intraoperative fixation of HTO procedures.

Sectioning the anterolateral ligament did not increase tibiofemoral translation or rotation in an ACL-deficient cadaveric model.

PURPOSE: The anterolateral ligament (ALL) has been proposed as a possible extra-articular stabiliser of the knee. Injury to the ALL may result in residual instability following surgical reconstruction of a ruptured anterior cruciate ligament (ACL). Few studies have evaluated the biomechanical role of the ALL. The purpose of this study was to investigate whether sectioning the ALL would have an influence on tibiofemoral translation or rotation during the anterior drawer, Lachman, pivot shift, external rotation, and internal rotation tests in an ACL-deficient knee. METHODS: Only whole-body specimens having an ALL were included in this study. Lachman, anterior drawer, external rotation, and internal rotation tests were performed manually. Pivot shift test was done using a mechanised pivot shifter. The amount of tibiofemoral translation and rotation was recorded by a navigation system. Each specimen was tested in its native state, after sectioning the ACL, and after combined sectioning of the ACL and the ALL. RESULTS: In six out of 14 cadaveric knees, an ALL could be identified. The ACL-deficient knee had significantly more tibiofemoral translation and rotation compared to the native knee (P < 0.05). However, no changes in the magnitudes of translation or rotation were seen after subsequent sectioning of the ALL compared to the ACL-deficient knee (P > 0.05). CONCLUSION: Adding an ALL lesion in an ACL-deficient knee did not increase tibiofemoral instability in this cadaveric model. It remains unclear whether injury to the ALL would result in substantial knee instability in the setting of ACL injury in vivo. Further research is warranted to fully elucidate the role of the ALL during knee kinematics and to determine in which scenarios ALL repair would be warranted. Understanding the function of the ALL may improve the current treatment strategies for ACL ruptures.

Preoperative virtual reduction reduces femoral malrotation in the treatment of bilateral femoral shaft fractures.

INTRODUCTION: In bilateral femoral shaft fractures, significant malrotation (>15°) occurs in about 40 % of cases after intramedullary nailing. Most of the methods that provide rotational control during surgery are based on a comparison to the intact femur and, thus, not applicable for bilateral fractures. In this study, we evaluated if preoperative virtual reduction can help improving rotational alignment in patients with bilateral femoral shaft fractures. MATERIALS AND METHODS: Seven patients with bilateral femoral shaft fractures were initially treated with external fixation of both femurs. After obtaining a CT scan of both legs, the fractures were reduced virtually using the software program VoXim®, and the amount and direction of rotational correction were calculated. Subsequently, the patients were treated by antegrade femoral nailing and rotation was corrected to the preoperatively calculated amount. RESULTS: After external fixation, the mean rotational difference between both legs was 15.0° ± 10.2°. Four out of seven patients had a significant malrotation over 15°. Following virtual reduction, the mean rotational difference between both legs was 2.1° ± 1.2°. After intramedullary nailing, no case of malrotation occurred and the mean rotational difference was 6.1° ± 2.8°. CONCLUSIONS: Preoperative virtual reduction allows determining the pretraumatic femoral antetorsion and provided useful information for the definitive treatment of bilateral femoral shaft fractures. We believe that this procedure is worth being implemented in the clinical workflow to avoid malrotation after intramedullary nailing.

[Dynamic versus static cement spacer in periprosthetic knee infection: A meta-analysis]. / Dynamischer vs. statischer Zementspacer in der Knietotalendoprotheseninfektion: Eine Metaanalyse.

BACKGROUND: The standard of care for treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is two-stage revision arthroplasty. The cement spacer in the interim period can be classified as either a static/non-articulating spacers (e.g., traditionally simple cement blocks) or a mobile/articulating spacer. OBJECTIVES: The goal of the present meta-analysis is to analyze the outcomes with regard to infection control between dynamic and static knee spacers in the treatment of infected TKA with a minimum 3-year follow-up. MATERIALS AND METHODS: We systematically reviewed the literature for potentially relevant articles addressing two-stage revision of an infected TKA using the MEDLINE computerized literature databases. Only 25 articles studies with a minimum follow-up examination of 36 months met the inclusion criteria and were analyzed with regard to infection control after reimplantation between static (318 cases) and dynamic group (700 cases). RESULTS: At latest follow-up, the eradication rate in the dynamic group was 89.7% (range 63-100%; SD 9.1) and in the static group 84.8% (range 67-92.4%; SD 7.8; p = 0.32). We are unable to comment on the Hospital for Special Surgery (HSS) Score and complication rates between static and dynamic spacers because the majority of the studies did not report on this. CONCLUSION: The data show that there are no differences regarding infection control between static and dynamic spacers in the treatment of infected TKA.

Intraoperative imaging of the shoulder: A comparison of two- and three-dimensional imaging techniques.

BACKGROUND: Isocentric three-dimensional C-arms allow for more effective intraoperative fracture reduction control compared to two-dimensional imaging techniques. However, this design is not appropriate for shoulder scanning. OBJECTIVE: To assess the feasibility of using a newer generation variable isocentric flat detector 3D C-arm for intraoperative glenohumeral and acromioclavicular joint assessment and to compare the accuracy of its intraoperative 3D imaging technology to a standard two-dimensional (2D) flat detector fluoroscope. METHODS: Five whole-body human cadavers were used (ten shoulders). Native shoulder scans were obtained. A glenohumeral arthrotomy was performed and several injuries and procedures were simulated. Five independent orthopaedic surgeons reviewed each scan and filled out a questionnaire assessing the quality of the images using a visual analog scale (VAS) and a points scoring system. RESULTS: The examiners rated the 3D images as very-good-to-excellent according to the established parameters: image quality; visualization of the corticalis and the spongiosa; delineation of the joint surface; presence of artifacts; and clinical assessment capability. This high quality of the images led to a higher interobserver reliability for 3D images compared to 2D images. CONCLUSIONS: Variable isocentric 3D C-arm technology is feasible for intraoperative assessment of shoulder procedures. Assessment of 3D images in shoulder procedures showed better interexaminer reliability in this experiment compared to 2D images. With the aid of intraoperative 3D shoulder imaging, intraoperative 3D C-arm navigation could help improve accuracy in the clinical setting.

Effect of medial opening wedge high tibial osteotomy on intraarticular knee and ankle contact pressures.

High tibial osteotomy (HTO) is a commonly used surgical technique for treating moderate osteoarthritis (OA) of the medial compartment of the knee by shifting the center of force towards the lateral compartment. Previous studies have documented the effects of HTO on the biomechanics of the knee. However, the effects of the procedure on the contact pressures within the ankle joint have not been as well described. Seven cadavers underwent an HTO procedure with sequential 5° valgus realignment of the leg up to 15° of correction. An axial force of up to 550 N was applied and the intraarticular pressure was recorded. Minor valgus realignment of the proximal tibia does not significantly alter the biomechanics of the ankle. However, moderate-to-large changes in proximal tibial alignment result in significantly decreased tibiotalar contact surface area and in changes in intraarticular ankle pressures. These findings are clinically relevant, as they provide a biomechanical rationale for the diagnosis and treatment of ankle symptoms in the setting of lower limb malalignment or after alignment correction procedures.

A cadaver study comparing intraoperative methods to analyze lower limb alignment.

BACKGROUND: Conventional intraoperative determination of lower limb alignment is essential for orthopedic surgical treatment. Current methods include the cable, alignment rod, and axis board methods. QUESTION/PURPOSES: Are there differences in accuracy and reliability? What are the individual differences in applicability and radiation exposure? METHODS: Twenty legs from 12 fresh-frozen cadavers were randomly selected. After fixation of the legs, measurements were performed using the cable, alignment rod, and axis board methods. Afterwards, all cadavers were subjected to CT scanning. Intersection of the mechanical leg axis with the tibia plateau was calculated as the percentage of the tibia plateau, beginning at the medial border (0%) and ending at the lateral border (100%). Results are presented as mean ± standard deviation (SD). RESULTS: Compared with CT measurements, differences of the intersection at the tibia plateau were 3.9 ± 8.5% with the cable method, 3.6 ± 7.6% using the alignment rod, and 3.6 ± 9.6% using the axis board. The difference among all measurements was not statistically significant (p = 0.450). The average intersection of the mechanical axis was 43.95 ± 5.15% using the cable method, 43.93 ± 5.49% using the alignment rod, and 43.77 ± 5.92% using the axis board. CT measurements revealed an average intersection of 42.46 ± 5.22%. There was no statistically significant difference among conventional results (p = 0.976). We demonstrated good intraobserver reliability for all three methods (cable method, ICC = 0.97; alignment rod, ICC = 0.95; and axis board, ICC = 0.96). There were no statistically significant differences regarding radiation time (p = 0.349) or dose area product (p = 0.823). CONCLUSIONS: All described measurements demonstrated valid measurement of lower limb alignment. With minimal effort, all three methods present a practical and uncomplicated way to control the mechanical axis.

Radiological outcome and intraoperative evaluation of a computer-navigation system for femoral nailing: a retrospective cohort study.

AIM: Intraoperative determinations of femoral antetorsion and leg length during fixation of femoral shaft fractures present a challenge. In femoral shaft fracture fixations, a computer-navigation system has shown promise in determining antetorsion and leg length discrepancies. This retrospective cohort study aimed to determine whether the use of computer navigation during femoral nailing procedures reduced postoperative femoral malrotation and leg length discrepancy, as well as the number of revision cases. We also sought to determine whether radiation exposure time was reduced when computer navigation was used. MATERIALS AND METHODS: Of 246 patients treated for femoral shaft fractures between 2004 and 2012, we selected those that received postoperative computed tomography for rotation and leg length control. We included 24 patients who received navigation-assisted treatments and 48 who received unassisted treatments, matched for age, sex, and fracture type. All patients were treated by femoral nailing. RESULTS: The groups showed significant differences in the mean (standard deviation (SD) delay before surgery (navigation-assisted vs. unassisted groups: 8.5 ± 3.2 vs. 5.2 ± 5.8 days; P<0.05) and surgery times (163.7 ± 43.94 vs. 98.3 ± 28.13 min; P<0.001). The groups were significantly different in the mean (SD) radiation exposure time (4.43 ± 1.35 vs. 3.73 ± 1.5 min; P=0.042), and were not significantly different in the postoperative femoral antetorsion difference (8.83 ± 5.52° vs. 12.4 ± 9.2°; P=0.056), or in the postoperative length discrepancy (0.92 ± 0.75 vs. 0.95 ± 0.94 cm; P=0.453). Four (16.7%) navigation-assisted and 15 (31.25%) unassisted surgeries got revision for torsion and/or length corrections. CONCLUSION: Our results showed that, compared to unassisted femoral surgery, the computer-navigation system did not improve postoperative results or reduce radiation exposure. In the future, improvements in handling and application could facilitate the workflow and may provide better postoperative results. Currently, computer navigation may provide advantages for complicated or sophisticated cases, such as complex three-dimensional deformity corrections. LEVEL OF EVIDENCE: Level III.

Range of motion assessment of the shoulder and elbow joints using a motion sensing input device: a pilot study.

BACKGROUND: Motion sensing input devices could provide a practical and low-cost alternative method for repeated range of motion measurements. This study aimed to assess the reliability, accuracy and time requirements of a motion sensing input device (Microsoft Kinect) for ROM measurements comparing it with goniometer based measurements and subjective estimation. MATERIAL AND METHODS: Full ROM was measured in 14 shoulder and elbow joints using the different methods. The order was randomly selected and each movement was measured twice. The results were recorded in degrees and the time measured in seconds. RESULTS: In general, there was a poor to moderate agreement between the Kinect system compared to the goniometer. There was a good agreement between the goniometer-based and the subjective technique. The Kinect-based technique showed excellent test-retest reliability. CONCLUSION: The Kinect system showed good test-retest reliability, but lower accuracy compared to goniometer-based measurements. Improvements in patient positioning and measurement protocol standardization must be made before its implementation in clinical practice.

Laser method for intraoperative evaluation of lower extremity alignment: comparison of a novel technique to CT and a conventional method.

INTRODUCTION: Accurate restoration of mechanical alignment is an important factor in reconstructive surgery of the lower extremity. Conventional intraoperative methods, such as using an electrocautery cable, provide only a momentary evaluation of alignment. In this study, we evaluated a novel technique using a laser emitter, which projected the mechanical axis of the lower extremity, providing continuous intraoperative information on alignment. MATERIALS AND METHODS: Alignment of 16 cadaver lower extremities was measured using the electrocautery cable method, the laser method, and CT scan as the standard measurement. The mechanical axis was defined by a line from the center of the femoral head to the center of the ankle. For simplifying measurements the intersection with the tibial plateau was divided into percentages from the medial border (0 %) to the lateral border (100 %). For using the laser method a laser emitting and laser catching device was developed, which is positioned and centered on the femoral head and the ankle using an image intensifier. By catching the laser on the knee region the actual mechanical axis is marked. RESULTS: The data demonstrated good correlation of the laser method when compared to the cable method (P = 0.44). Comparison of the average mechanical axis between cable method and CT (P = 0.819) and laser method and CT (P = 0.647) did not show a statistically significant difference. Average radiation time in comparison between cable method and laser method showed a statistically significant difference (P = 0.013), with the laser method requiring more radiation time. CONCLUSION: Determination of the mechanical axis during surgery remains a difficult clinical problem. Restoration of alignment is an important prognostic factor for surgical outcome. Based on these data, the laser method represents a simple, yet effective tool for continuous intraoperative evaluation of lower extremity alignment.

Effects of a WLAN-based real time location system on outpatient contentment in a Level I trauma center.

BACKGROUND: Pre-existing wireless local area network (WLAN) infrastructures enable the implementation of a real-time location system (RTLS) in the clinical setting. RTLS enable clinics to capture and process patient position data and link it with clinical data. The improvements in workflow and treatment brought about by RTLS may improve patient satisfaction. The aim of this study was to analyze the impact of a WLAN-based RTLS on outpatient satisfaction in our Level I trauma center. METHODS: This investigation was performed under different study arms (termed "phase"): In phase 0, patient satisfaction was determined (with a questionnaire) without RTLS implementation. In phase I, patient tracking with RTLS was performed, and satisfaction was determined (with a questionnaire); however, medical personnel did not utilize information gathered by RTLS. In phase II, patients were tracked by RTLS and satisfaction was determined (with a questionnaire); however, unlike phase I, the RTLS-acquired data was utilized by medical personnel. Information obtained from the questionnaire included: treatment rendered, subjective estimation of length of visit, subjective estimation of the most time-consuming portions of the clinic visit, subjective estimation of time of medical treatment, overall contentment, and contentment with wait time. In phase I and phase II, position data was automatically collected and analyzed. Statistical analyses were performed using Student's t-test and one-way Anova test. Significance level was set at 0.05. RESULTS AND DISCUSSION: In total, 1234 patients were included in our study (188 in phase 0, 540 in phase I, and 506 in phase II). Completed questionnaires were collected in 53% (654) of the patients. Statistically significant higher patient contentment and lower subjective wait times were noted in phase II patients as compared to phase I patients. However, no statistical differences in the questionnaire findings were noted between phase 0 and I patients. CONCLUSIONS: WLAN-based RTLS can help alleviate process inefficiencies associated with traditional clinic workflow methods, which can lead to improved patient satisfaction.