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Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 381 - 381
1 Dec 2013
Pourmoghaddam A Kreuzer SW Freedhand A
Full Access

INTRODUCTION:

Unicompartmental knee replacement (UKR) facilitates the use of smaller sized implants that require less bone resection and allows preservation of the anterior and posterior cruciate ligaments (ACL and PCL)[1]. Therefore, UKR preserves the intact kinematics and may improve the clinical outcomes especially compared to the outcomes of total knee replacement (TKA). Despite the known benefits of UKR in arthritis limited to one compartment, in multicompartment disease TKA remains the gold standard. Current TKA designs require the sacrifice of the ACL in all cases, whereas the surgeon can decide to use a cruciate sparing or substituting design altering normal knee kinematics. Performing bi-UKR or tri-UKR with traditional instruments is very challenging and rarely done due to the difficulty in establishing the correct spatial relationship of the separate components. Recent advances in robotic surgery have provided the opportunity to utilize partial knee replacements. The MAKO Rio platform is a surgeon-interactive robotic arm with haptic guidance that allows computer assisted planning and intraoperative accurate placement of multiple unicompartmental components including the bi-UKR. Currently there is a lack of understanding about the short-term and long-term clinical outcomes of the bi-UKR compared to the traditional TKA.

OBJECTIVES:

The objective of the current study was to investigate the differences in the clinical outcomes of bi-UKR and TKA.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 107 - 107
1 Dec 2013
Kreuzer SW Banks S Watanabe T Pourmoghaddam A
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Background

Discrepancies in patient outcomes after total knee arthroplasty have encouraged the development of different treatment options including early preventive interventions. In addition, improvements in surgical techniques and instrumentation have increased the accuracy of the surgeries. In this case study, we review the first robotic-arm assisted modular tricompartmental knee arthroplasty in which bone and soft tissues are conserved by employing a precise planning and execution technique.

Materials and Methods

A 63 year old Caucasian female with a Body Mass Index (BMI) of 27 presented to the surgeon (SK) with knee pain and a varus mechanical alignment. The patient received modular tri-unicompartmental arthroplasty performed with robotic-arm assistance; (see figure 1 for post-op radiograph). Range of Motion (ROM), Knee Society Score (KSS) and Knee Injury and Osteoarthritis Outcomes Score (KOOS) were measured pre-operatively and post-operatively at 6, 16, and 23 months. At 6 months post-op an in-depth in vivo kinematic analysis was conducted by using a validated fluoroscopic assessment technique [1]. The patient simulated stair climbing, kneeling activity, and deep lunge while under single plane fluoroscopy. Three dimensional models were created from CT scans and were matched to 2D fluoroscopic images for kinematic assessment.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 476 - 476
1 Dec 2013
Banks S Watanabe T Kreuzer SW Leffers K Conditt M Jones J Park B Dunbar N Iorgulescu A
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INTRODUCTION

There is strong current interest to provide reliable treatments for one- and two-compartment arthritis in the cruciate-ligament intact knee. An alternative to total knee arthroplasty is to resurface only the diseased compartments with discrete compartmental components. Placing multiple small implants into the knee presents a greater surgical challenge than total knee arthroplasty, and it is not certain natural knee mechanics can be maintained. The goal of this study was to compare functional kinematics in cruciate-intact knees with either medial unicondylar (mUKA), mUKA plus patellofemoral (mUKA+PF), or bi-unicondylar (biUNI) arthroplasty using discrete compartmental implants with preparation and placement assisted by haptic robotic technology.

METHODS

Nineteen patients with 21 knee arthroplasties consented to participate in an I.R.B. approved study of knee kinematics with a cruciate-retaining multicompartmental knee arthroplasty system. All subjects presented with knee OA, intact cruciate ligaments, and coronal deformity ranging from 7° varus to 4° valgus. All subjects received multicompartmental knee arthroplasty using haptic robotic-assisted bone preparation an average of 13 months (6–29 months) before the study. Eleven subjects received mUKA, five subjects received mUKA+PF, and five subjects received biUKA. Subjects averaged 62 years of age and had an average body mass index of 31. Combined Knee Society Pain/Function scores averaged 102 ± 28 preoperatively and 169 ± 26 at the time of study. Knee range of motion averaged −3° to 120° preoperatively and −1° to 129° at the time of the study.

Knee motions were recorded using video-fluoroscopy while subjects performed step-up/down, kneeling and lunging activities. The three-dimensional position and orientation of the implant components were determined using model-image registration techniques (Fig. 1). The AP locations of the medial and lateral condyles were determined by computing a distance map between the femoral condyles and the tibial articular surfaces.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 382 - 382
1 Dec 2013
Pourmoghaddam A Kreuzer SW Freedhand A
Full Access

INTRODUCTION:

The popularity of the direct anterior approach (DAA) for total hip arthroplasty (THA) is increasing as this approach causes less soft tissue damage and no muscular detachments and significantly shorter postoperative recovery time. Despite the promising early results the complication rate in the DAA cases has been concerning such as 9% rate in 247 DAA cases reported by Woolen et. al [1]. As DAA has not conventionally being used by surgeons these complications are expected to be reduced when the surgeons are more experienced. Therefore to better understand the issues that cause the postop complications in DAA we have conducted the present study.

OBJECTIVES:

The objective of the current study is to investigate the postop complications in individuals with arthritic hips treated by DAA THA over a period of 3.5 years by a one surgeon.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 108 - 108
1 Dec 2013
Pourmoghaddam A Kreuzer SW Freedhand A
Full Access

INTRODUCTION:

Proximally coated femoral stems have been designed to address the shortcomings of fully coated femoral stems including proximal femoral stress shielding. The design improvements leading to more optimized proximal femoral loading condition in the “Neck preserving stems” have increased the popularity of such implants (e.g., Minihip). Neck preserving stems depict better biological outcomes compared to more traditional stems 1 by utilizing more natural mechanical stress/strain distribution over the femur. These stems provide significant reduction in both torsional and bending moments at the stem/bone interface. This reduction may result in decreasing the micromotion and failure of osseointegration 1. Figure 1 demonstrates the differences between the cutting areas of a neck preserving versus traditional stem. The Minihip stem demonstrate a curved structure that is designed to match the shape of the femoral neck. The stability of the implant is achieved in the femoral neck and intertrochanteric area of the proximal femur. Further investigations are needed to establish a solid ground for the outcome of these stem in total hip arthroplasty (THA).

OBJECTIVES:

The current study was conducted to report the short-term clinical outcome of the THA by using Minihip neck preserving stem.