INTRODUCTION

Achieving balance in TKA is critical in assuring favorable outcomes. But, in order to achieve quantifiably balanced loading values, is it more advantageous to make bony corrections or release soft-tissue? The answer to this question will be paramount in evaluating the most appropriate surgical techniques for use with new dynamic technology, thereby maximizing favorable clinical outcomes. Therefore, the purpose of this investigation was to evaluate a possible quantitative loading threshold, using intraoperative sensors, which may dictate surgical correction of bone versus soft-tissue release.

INTRODUCTION

Patient-reported satisfaction is a critical measure in understanding the clinical success of total knee arthroplasty. Yet, satisfaction levels in TKA patients are generally lower than THA patients; and surgeon-patient agreeability regarding clinical success is typically in discordance. Thus, the purpose of this evaluation was to report on the one-year satisfaction data of a group of sensor-assisted TKA patients, and compare that data to the average satisfaction reported in literature, as measured by a meta-analysis.

INTRODUCTION

The cost associated with the TKA revision burden is projected to reach 13 billion dollars, annually. Complications reported by post-TKA patients include: pain (44%, multilocational), sensation of instability (21% reason for revision), and joint stiffness (17% reason for revision); problems that may be attributed to soft-tissue imbalance. One of the possible reasons for the substantial prevalence of such complications is the subjectivity associated with defining soft-tissue balance. A priority must be placed on developing new objective methods with which to avoid costly post-operative complications, including the integration of intraoperative sensing technology. The purpose of this evaluation was to report on the disparity between the patient-reported outcomes scores of quantitatively balanced versus unbalanced patients, at 1-year, using a group of 135 multicenter patients.

High-intensity narrow-spectrum (HINS) light is a novel violet-blue light inactivation technology which kills bacteria through a photodynamic process, and has been shown to have bactericidal activity against a wide range of species. Specimens from patients with infected hip and knee arthroplasties were collected over a one-year period (1 May 2009 to 30 April 2010). A range of these microbial isolates were tested for sensitivity to HINS-light. During testing, suspensions of the pathogens were exposed to increasing doses of HINS-light (of 123mW/cm² irradiance). Non-light exposed control samples were also used. The samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration. Complete inactivation (greater than 4-log₁₀ reduction) was achieved for all of the isolates. The typical inactivation curve showed a slow initial reaction followed by a rapid period of inactivation. The doses of HINS-light required ranged between 118 and 2214 J/cm². Gram-positive bacteria were generally found to be more susceptible than Gram-negative.

As HINS-light uses visible wavelengths, it can be safely used in the presence of patients and staff. This unique feature could lead to its possible use in the prevention of infection during surgery and post-operative dressing changes.

Cite this article: Bone Joint J 2015;97-B:283–8.

The aim of this prospective multicentre study was to report the patient satisfaction after total knee replacement (TKR), undertaken with the aid of intra-operative sensors, and to compare these results with previous studies. A total of 135 patients undergoing TKR were included in the study. The soft-tissue balance of each TKR was quantified intra-operatively by the sensor, and 18 (13%) were found to be unbalanced. A total of 113 patients (96.7%) in the balanced group and 15 (82.1%) in the unbalanced group were satisfied or very satisfied one year post-operatively (p = 0.043).

A review of the literature identified no previous study with a mean level of satisfaction that was greater than the reported level of satisfaction of the balanced TKR group in this study. Ensuring soft-tissue balance by using intra-operative sensors during TKR may improve satisfaction.

Cite this article: Bone Joint J 2014;96-B:1333–8

Cubitus varus is the most frequent complication following the treatment of supracondylar humeral fractures in children. We investigated data from publications reporting on the surgical management of cubitus varus found in electronic searches of Ovid/MEDLINE and Cochrane Library databases. In 894 children from 40 included studies, the mean age at initial injury was 5.7 years (3 to 8.6) and 9.8 years (4 to 15.7) at the time of secondary correction. The four osteotomy techniques were classified as lateral closing wedge, dome, complex (multiplanar) and distraction osteogenesis. A mean angular correction of 27.6º (18.5° to 37.0°) was achieved across all classes of osteotomy. The meta-analytical summary estimate for overall rate of good to excellent results was 87.8% (95% CI 84.4 to 91.2). No technique was shown to significantly affect the surgical outcome, and the risk of complications across all osteotomy classes was 14.5% (95% CI 10.6 to 18.5). Nerve palsies occurred in 2.53% of cases (95% CI 1.4 to 3.6), although 78.4% were transient. No one technique was found to be statistically safer or more effective than any other.

Cite this article: Bone Joint J 2014;96-B:691–700.

We determined the short-term clinical outcome and migration within the bone of the humeral cementless component of the Instrumented Bone Preserving (IBP) total elbow replacement in a series of 16 patients. There were four men and 12 women with a mean age at operation of 63 years (40 to 81). Migration was calculated using radiostereometric analysis. There were no intra-operative complications and no revisions. At two-year follow-up, all patients showed a significant reduction in pain and functional improvement of the elbow (both p < 0.001). Although ten components (63%) showed movement or micromovement during the first six weeks, 14 (88%) were stable at one year post-operatively. Translation was primarily found in the proximal direction (median 0.3 mm (interquartile range (IQR) -0.09 to 0.8); the major rotational movement was an anterior tilt (median 0.7° (IQR 0.4° to 1.6°)). One malaligned component continued to migrate during the second year, and one component could not be followed beyond three months because migration had caused the markers to break off the prosthesis.

This study shows promising early results for the cementless humeral component of the IBP total elbow replacement. All patients had a good clinical outcome, and most components stabilised within six months of the operation.

Cite this article: Bone Joint J 2014;96-B:229–36.

Introduction

During primary total knee arthroplasty, the surgeon may encounter excessive medial collateral ligament tension while addressing a varus knee. This may be due to medial ligament/capsular complex contractures, and/or, due to the creation of a 0 degree mechanical axis in a varus knee. This tension leads to increased loading in the medial compartment, which contributes to an unbalanced extension and flexion gap. If uncorrected, this imbalance can lead to unfavorable clinical outcomes, including: pain, accelerated polyethylene degradation, joint instability, and limited ROM. Currently, intercompartmental soft-tissue balance is obtained by a subjective surgeon's “feel”. However, this method of judging soft-tissue tension is both variable and unreliable. Most surgeons can detect gross instability, but judging ligament tension is difficult. The following technique describes the integration of intraoperative microelectronic tibial inserts to assess and modify ligament tension, utilizing real-time dynamic sensor feedback

Introduction

Post-operative clinical outcomes of TKA are dependent on a multitude of surgical and patient-specific factors. Malrotation of the femoral and/or tibial component is associated with pain, accelerated wear of the tibial insert, joint instability, and unfavorable patellar tracking and dislocation. Using the transepicondylar axis to guide implantation of the femoral component is considered to be an accurate anatomical reference and is widely used. However, no gold standard currently exists with respect to ensuring optimal rotation of the tibial tray. Literature has suggested that implantation methods, which reference the tibial tubercle, reduce positioning outliers with more consistency than other anatomical landmarks. Therefore, the purpose of this evaluation is to use data collected from intraoperative sensors to assess the true rotational accuracy of using the mid-medial third of the tibial tubercle in 98 TKAs.

Introduction:

Most cases of hip osteoarthritis (OA) are believed to be caused by alterations in joint contact mechanics resulting from pathomorphologies such as acetabular dysplasia and acetabular retroversion. Over the past 13 years, our research group has focused on developing approaches for patient-specific modeling of cartilage and labrum in the human hip, and applying these approaches to study hip pathomorphology. The long term objective is to improve the understanding of the etiology of OA related to hip pathomorphology, and to improve diagnosis and treatment. The objectives of this presentation are to provide a summary of our subject-specific modeling approach, and to describe the results of our analysis of hips from three populations of subjects: normal, traditional dysplastic, and retroverted.

This presentation will provide an overview of the interdisciplinary research program on hip pathomorphology at the University of Utah, including studies of dysplasia and femoracetabular impingement. The discussion will emphasize the implications of the research findings for hip preserving surgery

Background:

A large percentage of the patients who present for unilateral TKA have bilateral disease. Performing simultaneous, bilateral TKA has been debated and currently there is no consensus on the risks and benefit of this approach. In addition, specific selection criteria have not been defined to more accurately identify which patients are potentially appropriate candidates for this approach.

Introduction

Flexion instability of the knee accounts for, up to, 22% of reported revisions following TKA. It can present in the early post-operative phase or present— secondary to a rupture of the PCL— in the late post-operative phase. While most reports of instability occur in conjunction with cruciate retaining implants, instability in a posterior-stabilized knee is not uncommon. Due to the prevalence of revision due to instability, the purpose of constructing the following techniques is to utilize intraoperative sensors to quantify flexion gap stability.

Infection rates following arthroplasty surgery are between 1–4%, with higher rates in revision surgery. The associated costs of treating infected arthroplasty cases are considerable, with significantly worse functional outcomes reported. New methods of infection prevention are required. HINS-light is a novel blue light inactivation technology which kills bacteria through a photodynamic process. The aim of this study was to investigate the efficacy of HINS-light for the inactivation of bacteria isolated from infected arthoplasty cases.

Specimens from hip and knee arthroplasty infections are routinely collected to identify causative organisms. This study tested a range of these isolates for sensitivity to HINS-light. During testing, bacterial suspensions were exposed to increasing doses of HINS-light of (123mW/cm² irradiance). Non-light exposed control samples were also set-up. Bacterial samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration.

Complete inactivation was achieved for all Gram positive and negative microorganisms

More than a 4-log reduction in Staphylococcus epidermidis and Staphylococcus aureus populations were achieved after exposure to HINS-light for doses of 48 and 55 J/cm², respectively. Current investigations using Escherichia coli and Klebsiella pneumoniae show that gram-negative organisms are also susceptible, though higher doses are required.

This study has demonstrated that HINS-light successfully inactivated all clinical isolates from infected arthroplasty cases. As HINS-light utilises visible-light wavelengths it can be safely used in the presence of patients and staff. This unique feature could lead to possible applications such as use as an infection prevention tool during surgery and post-operative dressing changes.

Acetabular component positioning is highly correlated with total hip arthroplasty (THA) outcomes. Multiple reports however indicate that less than 50% of acetabular cups are placed within surgeon-desired ranges for abduction and anteversion angles when using conventional cup positioning techniques. Issues with improper placement include instability-dislocation, impingement and impact on range of motion, polyethylene wear, leg length discrepancy, and gait mechanics. Accuracy in placement of the acetabular component is complicated by the need to estimate cup impactor angles to create desired cup position. A low cost approach to THA using Image-based Ultrasonic Guidance (IUG) (Orthosensor, Sunrise, FL) coupled to existing surgical tools is presented. IUG utilises acoustic measurement techniques for achieving optimal component positioning and leg length. A precisely machined Hip Test Fixture (HTF) has been built to simulate the anatomical pelvis, acetabular cup, and femur to validate system accuracy.

The IUG was affixed to the HTF to demonstrate placement of the cup during THA. The HTF was loaded onto a 27-inch Graphic User Interface (GUI) providing three-dimensional CAD data of the HTF. Registration points included the Iliac Crest and 10 points around the acetabular cup. These points were mapped to the CAD data by the GUI. The HTF was set to 45° of abduction and 0° of version to begin testing. Abduction and version were measured over a +15° range in 1-degree increments while leg length and offset were measured over a +5mm range in 2mm increments. A high-resolution coordinate measurement machine (FaroArm EDGE) verified the accuracy and margin of error for inclination, version, leg length and offset at each increment.

The HTF provided a precise means for evaluating IUG system accuracy of simulated THA in a controlled environment. Acceptable margins of error were reported on the HTF: mean error for version was 0.36° (SD 0.02°; 0.25° to 0.38°); mean error for inclination was 1.04° (SD 0.52°; 0.48° to 1.66°); mean error for leg length and offset were respectively 0.36mm (SD 0.86mm; −0.65 to 1.55mm) and 0.41mm (SD 0.28; 0.05 to 0.80mm).

IUG provides a means for achieving acceptable precision and accuracy in component placement during THA as evaluated with the HTF. Further study is however necessary to correlate accuracy of IUG with clinical utility and short-term clinical outcomes.

Infection rates following arthroplasty surgery are between 1–4%, with higher rates in revision surgery. The associated costs of treating infected arthroplasty cases are considerable, with significantly worse functional outcomes reported. New methods of infection prevention are required. HINS-light is a novel blue light inactivation technology which kills bacteria through a photodynamic process. The aim of this study was to investigate the efficacy of HINS-light for the inactivation of bacteria isolated from infected arthroplasty cases.

Specimens from hip and knee arthroplasty infections are routinely collected to identify causative organisms. This study tested a range of these isolates for sensitivity to HINS-light. During testing, bacterial suspensions were exposed to increasing doses of HINS-light of (123 mW/cm² irradiance). Non-light exposed control samples were also set-up. Bacterial samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration.

Complete inactivation (greater than a 4-log reduction) was achieved for all of the clinical isolates from infected arthroplasty cases. The typical inactivation curve showed a slow initial reaction followed by a period of rapid inactivation. The doses of HINS-light exposure required ranged from 118–2214 J/cm² respectively. Gram-positive bacteria were generally found to be more susceptible than Gram-negative.

This study has demonstrated that HINS-light successfully inactivated all clinical isolates from infected arthroplasty cases. As HINS-light utilises visible-light wavelengths it can be safely used in the presence of patients and staff. This unique feature could lead to possible applications such as use as an infection prevention tool during surgery and post-operative dressing changes.

In a time of limited resources, the debate continues over which types of hip prosthesis are clinically superior and more cost-effective. Orthopaedic surgeons increasingly need robust economic evidence to understand the full value of the operation, and to aid decision making on the ‘package’ of procedures that are available and to justify their practice beyond traditional clinical preference.

In this paper we explore the current economic debate about the merits of cemented and cementless total hip replacement, an issue that continues to divide the orthopaedic community.

Cite this article: Bone Joint J 2013;95-B:874–6.

At our institution surgical correction of symptomatic flat foot deformities in children has been guided by a paradigm in which radiographs and pedobarography are used in the assessment of outcome following treatment. Retrospective review of children with symptomatic flat feet who had undergone surgical correction was performed to assess the outcome and establish the relationship between the static alignment and the dynamic loading of the foot.

A total of 17 children (21 feet) were assessed before and after correction of soft-tissue contractures and lateral column lengthening, using standardised radiological and pedobarographic techniques for which normative data were available.

We found significantly improved static segmental alignment of the foot, significantly improved mediolateral dimension foot loading, and worsened fore-aft foot loading, following surgical treatment. Only four significant associations were found between radiological measures of static segmental alignment and dynamic loading of the foot.

Weakness of the plantar flexors of the ankle was a common post-operative finding. Surgeons should be judicious in the magnitude of lengthening of the plantar flexors that is undertaken and use techniques that minimise subsequent weakening of this muscle group.

Cite this article: Bone Joint J 2013;95-B:706–13.

Introduction

Optimized tibial tray rotation during a total knee replacement (TKR) is critical for tibiofemoral congruency through full range of motion, as it affects soft tissue tension, stability and patellar tracking. Surgeons commonly reference the tibial tubercle, or the “floating tibial tray,” while testing the knee in flexion and extension. Utilization of embedded sensors may enable the surgeon to more accurately assess tibiofemoral contact points during surgery.

Infection rates following arthroplasty surgery are between 1–4%, with higher rates in revision surgery. The associated costs of treating infected arthroplasty cases are considerable, with significantly worse functional outcomes reported. New methods of infection prevention are required. HINS-light is a novel blue light inactivation technology which kills bacteria through a photodynamic process. The aim of this study was to investigate the efficacy of HINS-light for the inactivation of bacteria isolated from infected arthoplasty cases.

Specimens from hip and knee arthroplasty infections are routinely collected to identify causative organisms. This study tested a range of these isolates for sensitivity to HINS-light. During testing, bacterial suspensions were exposed to increasing doses of HINS-light of (123mW/cm2 irradiance). Non-light exposed control samples were also set-up. Bacterial samples were then plated onto agar plates and incubated at 37°C for 24 hours before enumeration.

Complete inactivation was achieved for all Gram positive and negative microorganisms More than a 4-log reduction in Staphylococcus epidermidis and Staphylococcus aureus populations were achieved after exposure to HINS-light for doses of 48 and 55 J/cm2, respectively. Current investigations using Escherichia coli and Klebsiella pneumoniae show that gram-negative organisms are also susceptible, though higher doses are required.

This study has demonstrated that HINS-light successfully inactivated all clinical isolates from infected arthroplasty cases. As HINS-light utilises visible-light wavelengths it can be safely used in the presence of patients and staff. This unique feature could lead to possible applications such as use as an infection prevention tool during surgery and post-operative dressing changes.