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Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 59 - 59
1 Mar 2017
Noble P Foley E Simpson J Gold J Choi J Ismaily S Mathis K Incavo S
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Introduction

Numerous factors have been hypothesized as contributing to mechanically-assisted corrosion at the head-neck junction of total hip prostheses. While variables attributable to the implant and the patient are amenable to investigation, parameters describing assembly of the component parts can be difficult to determine. Nonetheless, increasing evidence suggests that the manner of intraoperative assembly of modular components plays a critical role in the fretting and corrosion of modular implants. This study was undertaken to measure the magnitude and direction of the impaction forces applied by surgeons in assembling modular head-neck junctions under operative conditions where both the access and visibility of the prosthesis may potentially compromise component fixation.

Methods

A surrogate consisting of the lower limb with overlying soft tissue was developed to simulate THR performed via a 10cm incision using the posterior approach. The surrogate was modified to match the resistance of the body to retraction of the incision, mobilization of the femur and hammering of the implanted femoral component. An instrumented femoral stem (SL PLUS) was surgically implanted into the bone after attachment of 3 miniature accelerometers (Dytran Inc) in an orthogonal array to the proximal surface of the prosthesis. A 32mm cobalt chrome femoral head was mounted on the trunnion (12/14 taper, machined) of the femoral stem. 15 Board-certified and trainee surgeons replicated their surgical technique in exposing the femur and impacting the modular head on the tapered trunnion. Impaction was performed using an instrumented hammer (5000 Lbf Dytran impact hammer) that provided measurements of the magnitude and temporal variation of the impact force. The components of force acting along the axis aof the neck and in the AP and ML directions were continuously samples using the accelerometers.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 457 - 457
1 Dec 2013
Michnick S Noble P Sharma G Adams H Ismaily S Booth R Mathis K
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Introduction:

With the growing emphasis on the cost of medical care, there is renewed interest in the productivity and efficiency of surgical procedures. We have developed a method to systematically examine the efficiency of the surgical team during primary total knee replacement (TKR). In this report, we present data derived from a series of procedures performed by different joint surgeons. This data demonstrates a variation between the duration and efficiency of each step in this procedure and its relationship to the experience and coordination of the surgeon working with the scrub team.

Methods:

After consent was achieved, videotaped recordings were prepared of ten primary TKR procedures performed by five highly experienced joint surgeons. For quantitative analysis, each procedure was divided into 7 principal tasks from initial incision to wound closure. In order to quantify efficiency, we recorded the occurrence of events leading to delays in each step of the procedure (Table 1). Starting with a total score of 100 points, deductions were made, based on the number of delaying events and its impact on the efficiency of the procedure. A final score for the surgery was then determined using the individual scores from each principal task. The experience of each member of the surgical team in participating in TKR, and in working with the surgeon, were recorded and correlated with the total efficiency score for the entire procedure.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 455 - 455
1 Dec 2013
Noble P Ramkumar P Cookston C Ismaily S Gold J Lawrie C Mathis K
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Introduction:

Malrotation of the tibial component is a common error in TKR, and has been frequently cited as the cause of clinical symptoms. Correct rotational orientation of the tibial tray is difficult to achieve because the resected surface of the tibia is internally rotated and is not symmetrical in shape. This suggests that anatomically contoured components may lead to improved rotational positioning.

This study was undertaken to test the hypotheses:

Use of an anatomically shaped tibial tray can reduce the prevalence of malrotation and cortical over-hang in TKA while increasing coverage of the resected tibial surface, and

Component shape has more influence on the results of surgical trainees compared to experienced surgeons.

Materials and Methods:

A standard symmetric design of tibial tray was developed from the profiles of 3 widely used contemporary trays. Corresponding asymmetric profiles were generated to match the average shape of the resected surface of the tibia based on a detailed morphometric analysis of anatomic data. Both designs were proportionally scaled to generate a set of 7 different sizes. Computer models of eight tibias were selected from a large anatomic collection. The proximal tibia was resected perpendicular to the canal axis with a posterior slope of 5 degrees at a depth of 5 mm (medial). Eleven experienced joint surgeons and twelve trainees individually determined the ideal size and placement of each tray on each of the 8 resected tibias. The rotational alignment, coverage of the resected bony surface, and extent of overhang of the tray beyond the cortical boundary were measured for each implantation. Differences in the parameters defining the implantations of the surgeons and trainees were evaluated statistically.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 423 - 423
1 Dec 2013
Meftah M Hwang K Ismaily S Incavo S Mathis K Noble P
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Introduction:

Proper rotational alignment of the tibial component is a critical factor in the outcome of total knee arthroplasty (TKA), and misalignment has been implicated as a major contributing factor to several mechanisms of TKA failure. In this study we examine the relationship between bony and soft tissue tibial landmarks against the knee motion axis (plane that best approximates tibiofemoral motion through range of motion).

Methods:

The kinematic motions of 16 fresh-frozen lower limb specimens were analyzed in simulated lunging and squatting. All the tendons of the quadriceps and hamstrings were independently loaded to simulate a lunging or squatting maneuver. All specimens underwent CT scan and the 3D position of the knee was virtually reconstructed. Ten anatomic axes were identified using both the intact tibia and the resected tibial surface. Two axes were normal vectors to either the medial-lateral plateau center or the posterior tibial surface. Seven axes were defined between the tibial tubercle (the most prominent point, center of the tubercle, or medial third of the tubercle) and soft tissue landmarks of the tibia (the medial insertion of the patellar tendon, the center of the PCL and ACL, and the tibial spines). The last axis was the Knee Motion Axis (KMA), which was defined as the longitudinal axis of the femur from 30 to 90 degrees of flexion.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 85 - 85
1 Dec 2013
Noble P Ismaily S Gold J Stal D Brekke A Alexander J Mathis K
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Introduction:

Despite all the attention to new technologies and sophisticated implant designs, imperfect surgical technique remains a obstacle to improving the results of total knee replacement (TKR). On the tibial side, common errors which are known to contribute to post-operative instability and reduced function include internal rotation of the tibial tray, inadequate posterior slope, and excessive component varus or valgus. However, the prevalence of each error in surgeries performed by surgeons and trainees is unknown. The following study was undertaken to determine which of these errors occurs most frequently in trainees acquiring the surgical skills to perform TKR.

Materials and Methods:

A total of 43 knee replacement procedures were performed by 11 surgical trainees (surgical students, residents and fellows) in a computerized training center. After initial instruction, each trainee performed a series of four TKR procedures in cadavers (n = 2) and bone replicas (n = 2) using a contemporary TKR instrument set and the assistance of an experienced surgical instructor. Prior to each procedure, computer models of each cadaver and/or bone replica tibia were prepared by reconstructing CT scans of each specimen. All training procedures were performed in a navigated operating room using a 12 camera motion analysis system (Motion Analysis Inc.) with a spatial resolution in all three orthogonal directions of ± 0.15 mm.

The natural slope, varus/valgus alignment, and axial rotation of the proximal tibial surface were recorded prior to surgery and after placement of the tibial component. For evaluation of all data, acceptable limits for implantation were defined as: posterior slope: 0–10°; varus/valgus inclination of tibial resection: ± 3°; and external rotation: 0–10°.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 176 - 176
1 Jun 2012
Ismaily S Turns L Gold J Alexander J Mathis K Noble P
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Introduction

Although the “learning curve” in surgical procedures is well recognized, little data exists documenting the accuracy of surgeons in performing individual steps of orthopedic procedures. In this study we have used a validated computer-based training system to measure variations instrument placement and alignment in TKA, specifically those relating to tibial preparation.

Methods

Eleven trainees (surgical students, residents and fellows) were recruited to perform a series of 43 knee replacement procedures in a computerized training center. After initial instruction, each trainee performed a series of four TKA procedures in cadavers (n=2) and bone replicas (n=2) using a contemporary TKA instrument set and the assistance of an experienced surgical instructor. The Computerized Bioskills system was utilized to monitor the placement and orientation of the proximal tibial osteotomy and the tibial tray.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 435 - 435
1 Nov 2011
Goytia R McArthur B Noble P Ismaily S Irwin D Usrey M Conditt M Mathis K
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Several studies have suggested that, in TKR, gender specific-prostheses are needed to accommodate anatomic differences between males and females. This study was performed to examine whether gender is a factor contributing to the variability of the size, shape and orientation of the patellofemoral sulcus.

3D computer models of the femur were reconstructed from CT scans of 20 male and 20 female femora. The patellofemoral groove was quantified by measuring landmarks at 10 degree increments around the epicondylar axis. The orientation of the groove was defined by the tracking path generated by a sphere moving from the top of the groove to the intercondylar notch. To assess the influence of gender on the shape of the distal femur, all morphologic parameters were normalized for differences in bone size.

Overall, the distal femur was 15% larger in males compared to females. The male condyles were 4% wider than the female for constant AP depth (p=0.13). When normalized for bone size, there was no gender difference in most patello-femoral dimensions, including the length, width, angle or tilt of the sulcus. Female femora had a less prominent medial anterior ridge (p=0.07), and a larger normalized radius of curvature of the tracking path (p=0.03). In addition, the orientation of the sulcus differed by 1–2 degrees in both the coronal and axial planes. Overall, gender explained 4.7% of the anatomic variation of the parameters examined, varying from 0 to 15.9%.

The size, shape and orientation of the patello-femoral groove are highly variable.

While the patello-femoral morphology of male and female femora are very similar, some of the anatomic variability is related to gender, particularly the prominence of the medial ridge and the sulcus radius of curvature. The biomechanical and clinical significance of these differences after TKA have yet to be determined.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 203 - 203
1 Mar 2010
Noble P Conditt M Thompson M Ismaily S Mathis K
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Introduction: Most surgeons agree on basic parameters defining a successful joint replacement procedure. However, the process of acquiring the skills to achieve this level of success on a reproducible basis is much less straightforward. In reality, it is generally not possible to impart surgical training without some level of risk to the patient, particularly if a particular trainee or procedure has a long learning curve. In an attempt to address these issues, we have developed a new computer-based training system to measure the technical results of hip and knee replacement surgery in both the operating room and the Bioskills Lab.

Description of the System: This system utilizes Surgical Navigation technology combined with data analysis and display routines to monitor the position and alignment of instruments and implants during the procedure in comparison with a preoperative plan. For bioskills training, the surgeon develops a preoperative plan on a computer workstation using accurate 3D computer models of the bones and appropriate implants. The surgeon then performs the entire procedure using the cadaver or sawbone model. During the procedure, the position and orientation of the bones, each surgical instrument, and the trial components are measured with a three-dimensional motion analysis system. Through analysis of this data, the surgeon is able to view each step of the surgical procedure, the placement of each instrument with respect to each bone, and the consequences of each surgical decision in terms of the final placement of the prosthetic components When errors are detected in the implementation of the preoperative plan, the surgeon is able to replay each step of the procedure to examine the precise placement of each instrument with respect to each bone and the consequences of each surgical decision in terms of leg length, alignment and range-of-motion.

Conclusions: This system allows us to measure the technical success of a surgical procedure in terms of quantifiable geometric, spatial, kinematic or kinetic parameters. It also provides postoperative feedback to the surgeon by demonstrating the specific contributions of each step of the surgical procedure to deviations in final alignment or soft tissue instability. This approach allows surgeons to be trained outside the operating room prior to patient exposure. Once these skills have been developed, the surgeon is able to operate freely in the operating room without the risks associated with traditional surgical training, or the expense associated with intraoperative Surgical Navigation. The value of this approach in the training and accreditation of orthopedic staff warrants further investigation.