Studies have shown that dissatisfaction following TKA may stem from poor component placement and iatrogenic factors related to variability in surgical execution. A CT-based robotic assisted system (RA) allows surgeons to dynamically balance the joint prior to bone resection. This study aimed to determine if this system could improve TKA planning, reduce soft tissue releases, minimize bone resection, and accurately predict component size in varus knee. Four hundred and seventy four cases with varus deformity undergoing primary RATKA were enrolled in this prospective, single center and surgeon study. Patient demographics and intraoperative surgical details were collected. Initial and final 3-dimensional alignment, component position, bone resection depths, use of soft tissue releases, knee balancing gaps, and component size were collected intraoperatively. WOMAC and KOOS Jr. scores were collected 6 months, and 1 year postoperatively. Descriptive statistics were applied to determine the changes in these parameters between initial and final values.Introduction
Method
As the demographic of the patient population requiring revision total knee arthroplasty (rTKA) continues to expand, varying preoperative conditions and activity levels need to be taken into consideration when analyzing postoperative outcomes. Factoring in preoperative activity levels can help manage the expectations of patients. The purpose of this study was to analyze the outcomes of low and high activity patients receiving a contemporary rTKA. One hundred and eighty rTKA patients enrolled in a prospective, multicenter study were evaluated through 2 years postoperative. Patients were divided into groups based on preoperative activity level using the Lower Extremity Activity Scale (LEAS). Patients scoring between 1–7 were classified as ‘Low Activity’ (LA, N=104) and patients scoring 8–18 were classified as ‘High Activity’ (HA, N=76). Clinical and patient-reported outcomes were evaluated, with an additional quality of life analysis completed utilizing SF-6D scores obtained by transforming SF-36 scores through a method described by Brazier et al. and analyzed for effect size.INTRODUCTION
METHODS
Revision for instability has supplanted revision for aseptic loosening and revision for osteolysis since the advent of improved polyethylene inserts with changes in both sterilization techniques and cross-linking. Having the ability to judiciously choose a higher level of constraint may be beneficial in complex primary total knee arthroplasty (TKA) scenarios which can not be balanced through traditional surgical methods. The purpose of this work was to investigate short term outcomes and survivorship in cases where a greater stabilizing insert was used with a posterior stabalizing (PS) femur to address instability in flexion or extension. Two high volume TKA centers retrospectively reviewed cases in which a greater stabilizer insert was used with a primary PS knee system. The studied insert had +/− 2 degrees of varus-valgus coronal restraint as opposed the standard with no coronal constraint. The study inserts had 7 degrees of transverse plane rotational freedom. The inserts were used when extension balance was not achieved despite the usual soft tissue releases and a thicker insert resulted in a flexion contracture statically during the procedure. This situation typically occurred in the following patient groups: valgus knees with medial collateral (MCL) stretching, iatrogenic MCL injury, varus knees with lateral ligament complex stretching, the “double-varus” knee, and patients with a previous high tibial osteotomy. Intra-operatively patients were taken through a range of motion and trial implants were then placed. A cruciate retaining trial insert was then used to assess stability so that a true assessment could be made of ligament balance. Bone cuts were checked before ligament release. The usual releases were then performed to achieve balance including subperiosteal releases medially and laterally and pie-crusting when indicated. Repeat trial reductions were then performed once the final implants were cemented in place again using the cruciate retaining insert. If the soft tissue releases did not achieve balance and a thicker insert resulted in a flexion contracture then the greater stabilizer insert was selected over the PS insert. Knee Society Score and plain radiographs were collected at pre-op, 2 year and 5 year follow-up.Introduction
Methods
Total knee arthroplasty (TKA) is one of the most common orthopaedic procedures performed, and is projected to exponentially increase over the next 20 years. As primary TKA cases increase, so does the frequency of revisions. The primary goals for all TKA cases include alleviating pain and improving overall knee function. The objective of this study was to evaluate the change in outcomes as measured by the Knee Society Score (KSS) between primary and revision TKA systems. This data was collected as part of three prospective, post-market, multicenter studies comparing preoperative to 6-week data. Patients were stratified into two groups based on type of single radius knee device; Posteriorly Stabilized (PS) group and Total Stabilizer (TS) group. Early clinical outcomes based on the KSS and operative data were used to compare groups.1) INTRODUCTION
2) METHODS
For 30 years, uncemented anatomic hip stems have been implanted with documented clinical results[1,2]. Their geometry can be linked back to the geometry of the PCA and ABG stems. Modifications to date include stem length, body geometry, material, and reduction in distal geometry. New tools have been developed allowing anatomical measurements and analysis of three-dimensional digital femora geometry through CT scans[3]. The purpose of this study is to analyze three-dimensional contact of various anatomic hip stem designs using this technique. Six femora (57–87 yrs, 72–88 kg), were selected from a CT scan database (SOMA™) of 604 Caucasian bones. They were selected based on femoral anteversion (average +/−1.5 * std. dev.) with three measuring[4] 8–10° and three 31–33° of anteversion. The CT scans were segmented into cancellous/cortical bone and converted into CAD models in PRO/Engineer Wildfire (v.5). A/P views of the bones were scaled to a 120% magnification to allow three surgeons to surgically template and choose the stem size and location (maximizing fill (n = 1); restoring the head center (n = 2)) with two implant designs (1-Citation TMZF and 2-ABG II Monolithic, Stryker Orthopaedics, Mahwah). Measurements from templating were used to virtually implant CAD models of the implants into the bones (n = 36 bone/stem assemblies). The assemblies were imported into Geomagic Qualify 2012 for 3D deviation analysis comparing the coated region of the implant to the cortical-cancellous boundary. The analysis generated color map profiles based on the following categories: Contact (−2.0 to 0.5 mm), Conformity (0.5 to 2.0 mm), Proximity (2.0 to 5.0 mm), and Gap (5.0 to 12 mm) and the percent of the surface that was within each of these categories. These results were compared for patterns within and across the anatomic families.Introduction:
Methods:
Revision total knee arthroplasty (TKA) can be very complex in nature with difficulties/obstacles involving bone and soft tissue deficits, visualization and exposure, as well as alignment and fixation. Auxiliary devices such as augmentation and offset adapters help address these issues; however they increase the complexity of the reconstruction. The objective of this study was to show that use of a single radius revision TKA system allowing for minimal auxiliary revision devices can yield positive early clinical outcomes. This data was collected as part of a prospective, post-market, multicenter study. One hundred and twenty-five single radius revision TKA cases were evaluated. Surgical details were reviewed and cases were grouped based on type of auxiliary devices used. Group 1 included cases that used only femoral and/or tibial augments. Group 2 used femoral and/or tibial augments in conjunction with femoral and/or tibial offset adapters. Early clinical outcomes, operative data and radiographic findings were used to compare cases.Introduction:
Methods:
