The 2020 London International Hamstring Consensus meeting was convened to improve our understanding and treatment of hamstring injuries.

The multidisciplinary consensus panel included 14 International specialists on the management of hamstring injuries. The Delphi consensus process consisted of two rounds of surveys which were completed by 19 surgeons from a total of 106 participants. Consensus on individual statements was regarded as over 70% agreement between panel members.

The consensus group agreed that the indications for operative intervention included the following: gapping at the zone of injury (86.9%); high functional demands of the patient (86.7%); symptomatic displaced bony avulsions (74.7%); and proximal free tendon injuries with functional compromise refractory to non-operative treatment (71.4%). Panel members agreed that surgical intervention had the capacity to restore anatomy and function, while reducing the risk of injury recurrence (86.7%). The consensus group did not support the use of corticosteroids or endoscopic surgery without further evidence.

These guidelines will help to further standardise the treatment of hamstring injuries and facilitate decision-making in the surgical treatment of these injuries.

Problem

Total hip replacement (THA) is among the most common and highest total spend elective operations in the United States. However, up to 7% of patients have 90-day complications after surgery, most frequently joint dislocation that is related to poor acetabular component positioning. These complications lead to patient morbidity and mortality, as well as significant cost to the health system. As such, surgeons and hospitals value navigation technology, but existing solutions including robotics and optical navigation are costly, time-consuming, and complex to learn, resulting in limited uptake globally.

Introduction

Lumbar spine fusion in patients undergoing THA (total hip arthroplasty) is a known risk factor for hip dislocation with some studies showing a 400% increased incidence compared to the overall THA population. Reduced spine flexibility can effectively narrow the cup anteversion safe zone while alterations in pelvic tilt can alter the center of the anteversion safe zone. The use of precision cup alignment technology combined with patient-specific cup alignment goals based on preoperative assessment has been suggested as a method of addressing this problem. The current study assess the dislocation rate of THA patients with stiff or fused lumbar spines treated using surgical navigation with patient-specific cup orientation goals.

Introduction

The effect of spine-pelvis position and motion on hip arthroplasty function has been increasingly appreciated in the past several years. Some authors have stressed the importance of using precision technologies for component placement while others have advocated the use of dual mobility articulations or large bearings and lateralized liners in patients with fused lumbar spines. The current study assesses the prevalence of stiff and fused spines in an elective total hip arthroplasty population.

The Superior Hip Approach allows for safe reconstruction of the hip while maximizing preservation of the surrounding soft tissues. The procedure involves an incision in the hip joint capsule posterior to the gluteus medius and minimus and anterior to the short external rotators. The technique involves preparation of the femur in-situ through the superior femoral neck and then excision of the femoral head, which avoids the attendant soft tissue dissection or injury associated with dislocation of the native hip. After component implantation, the capsule is closed anatomically.

Two separate studies have demonstrated that over a 90-day period, patients whose hips were replaced using this technique consumed the least amount of cost of any patients treated by hip arthroplasty in the Commonwealth of Massachusetts. One study assessed all hips replaced in patients insured by Medicare over a four-year period. In this study, patients treated by the Superior Hip Approach were less costly by an average of more than $7,000 over 90 days. A second study assessed all hips replaced in patients insured by a large private insurer. This study showed again that patients treated by the Superior Hip Approach were the lowest cost patients. Notable, the cost on average was $23,500 less per procedure compared to the most well-known medical care organization in the state or roughly half the cost. Lower cost was due to both lower inpatient cost and reduced utilization of post-acute care resources. Since reduced resource utilization is a direct measure of accelerated recovery, these economic data combine with clinical outcomes and anatomical studies that document that the Superior Hip Approach is a reliable technique for achieving optimal results following THA.

INTRODUCTION

In the United States, the Centers for Medicare and Medicaid Services consider rates of unplanned hospital readmissions to be indicators of provider quality. Understanding the common reasons for readmission following total joint arthroplasty will allow for improved standards of care and better outcomes for patients. The current study seeks to evaluate the rates, reasons, and Medicare costs for readmission after total hip and total knee arthroplasty.

Economic data, clinical outcome studies, and anatomical studies continue to support the Superior Hip Approach as a preferred approach for improved safety, maximal tissue preservation, rapid recovery, and minimised cost.

Clinical studies show exceedingly low rates of all major complications including femur fracture, dislocation, and nerve injury.

Economic data from Q1 2013 to Q2 2016 demonstrate that CMS-insured patients treated by the Superior Hip Approach have the lowest cost of all patients treated in Massachusetts by an average of more than $7,000 over 90 days. The data show that the patients treated by the Superior Hip Approach have lower cost than any other surgical technique.

Matched-pair bioskills dissections demonstrate far better preservation of the hip joint capsule and short external rotators than the anterior approach.

Design principles include: Preservation of the abductors; Preservation of the posterior capsule and short external rotators; Preparation of the femur in situ prior to femoral neck osteotomy; Excision of the femoral head, thereby avoiding surgical dislocation of the hip; In-line access to the femoral shaft axis; Ability to perform a trial reduction; Independence from intra-operative imaging; Independence from a traction table; Applicable to at least 99% of THA procedures.

Pre-operative knowledge

Knowledge-based total hip arthroplasty is becoming increasingly recognised for improved safety, efficiency, and accuracy. Pre-operative knowledge of native and planned femoral anteversion, the exact size of implants, neck length and offset, and head lengths can serve to safely accelerate surgery and reduce the need for intra-operative imaging. Pre-operative knowledge of the effect on change in leg length and offset effected by specific implant combinations can serve to minimise undesired changes. The use of a smart mechanical navigation tool superimposed on this knowledge, can serve to easily and swiftly achieve optimal component position.

INTRODUCTION

Interest in tissue-preserving or minimally invasive total hip arthroplasty (THA) is increasing with focus toward decreased hospital stay, enhanced rehabilitation, and quicker recovery for patients. Two tissue-preserving techniques, the anterior and superior approaches to THA, have excellent clinical results, but little is known about their relative impact on soft tissue. The purpose of this study was to evaluate the type and extent of tissue damage after THA with each approach, focusing on abductors, short external rotators, and the hip capsule.

Goals for total hip arthroplasty include acceleration of recovery, optimisation of component placement, minimisation of peri-operative complications, and maximal preservation of surrounding soft tissues. Achieving these goals when combined with appropriate implant design and manufacture can lead to decades of excellent hip function.

With the exception of relatively rapid recovery, which can also be achieved with virtually all modern surgical exposures, the anterior hip approach fails to reliably achieve these goals. Problems with the anterior exposure for total hip arthroplasty are becoming increasingly recognised. Complications with equal or higher incidences than alternative exposures include: 1.) Early wound complications, 2.) Infection, 3.) Intra-operative and post-operative femur fracture, 4.) Greater trochanteric fracture, 5.) Dislocation, 6.) Femoral component loosening, 7.) Poor component placement, 8.) Poor soft tissue balance, 9.) Incisions with poor aesthetics and associated superficial hypaesthesia and dysaesthesia.

These complications may be in part due to: 1.) The anterior and posterior soft tissue releases often necessary to complete the exposure, 2.) Poor ability to anatomically repair the hip joint capsule, 3.) Reduced choices of femoral components with restriction generally to those with less robust fixation, 4.) The poorly extensile nature of the interval, 5.) The need to place the incision in the region of the flexion crease, 6.) The limited ability to assess soft tissue balance and impingement-free range of motion at the time of surgery, 7.) The undue reliance on unvalidated, inaccurate imaging techniques to assess component placement.

While experienced surgeons can achieve excellent results with the anterior (or virtually any other) exposure for total hip arthroplasty, the anterior exposure is by no means close to being a first among equals.

Excellent outcomes following total hip arthroplasty require both optimal soft-tissue management and precise planning and placement of prosthetic components. The use of detailed and dynamic three-dimensional surgical plans combined with smart mechanical instruments for component placement facilitates precise and efficient surgery. Interest in these technologies has increased recently as surgeons and institutions are now responsible for poor outcomes in a growing percentage of the patient population.

Cloud-based, patient-specific planning allows the surgeon to review and refine and execute surgical plans efficiently (HipXpert System, Surgical Planning Associates, Boston, MA). The surgical plans include cup size, cup orientation, stem size, head length, femoral anteversion, and planned change in leg length and offset, all in relation to the patients bony anatomy in 3D and multiplanar views. The associated smart tool is adjusted specifically for that patient and when docked, provides orientation information to the surgeon.

The system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases including by an independent study. This compares to a recent study of robotic methods that 88% of inclination and 84% for anteversion and to even greater inaccuracy of conventional surgery.

Cloud-based 3D planning combined with smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problems of component sizing, orientation, and version, offset, and leg length correction. Knowledge of component sizing pre-operatively can facility inventory management and allows the surgery team to better anticipate the surgeon's goals during the procedure.

The high and ever increasing cost of medical care worldwide has driven a trend toward new payment models. Event based models (such as bundled payment for surgical events) have shown a greater potential for care and cost improvement than population-based models (such as accountable care organizations). Since joint replacement is among the most frequent and costly surgical events in medicine, bundled payments for joint replacement episodes have been at the forefront of evolution from fee-for-service to value-based care models and episode-based healthcare reform in general.

Our education as surgeons in medical school, residency, fellowship, and in continuing education has been almost entirely non-economic in focus. Yet, we surgeons are now evolving from being primarily responsive for our patients' medical care to being also responsible for all expenditures associated with our patients' care. Similarly, while the cost of our patients' care was not even available to us, every dollar of expenditure for a patient's episode of care is now available to us in some circumstances. For example, a typical primary joint replacement episode may cost $30,000 for a patient insured by Medicare in the US. A surgeon performing 400 joint replacements per year is therefore authorizing upwards of $12M a year in health care spending by making the decisions to perform reconstructive procedures on those patients.

The risk for value-based surgical episodes of care can be born by various entities including hospital systems or the surgeons themselves. Recent evidence demonstrates that quality improves and cost decreases more rapidly when surgeons take primary responsibility and risk for episodes of care as compared to when a hospital system or third party takes primary responsibility and risk. Yet, as surgeons, our education in the field of medical economics, value-based episodes of care, and payment reform is only just beginning. The more we understand about the cost and value of the services that we order for our patients, the more leadership can provide as healthcare evolves. The current presentation will describe the specific cost of care for the primary joint replacement patient preliminary experience with accepting risk and responsibility for these patients. It is likely that our patients will be best served if we surgeons provide as much leadership as possible in their care, both medically and economically.

Distal neck modularity places a modular connection at a mechanically critical location, which is also the location that confers perhaps the greatest clinical utility. The benefits of increased clinical options at that location must be weighed against the potential risks of adding an additional junction to the construct. Those risks include prosthetic neck fracture, taper corrosion, metal hypersensitivity, and adverse local tissue reaction. Further, in-vitro testing of ultimate or fatigue strength of femoral component designs has repeatedly failed to predict behavior in-vivo, raising questions about the utility of in-vitro testing that does not incorporate the effect of mechanically assisted crevice corrosion into the test design.

The material properties of Ti alloy and CoCr alloy place limits on design considerations in the proximal femur. The smaller taper junctions that are necessary for primary reconstruction are particularly vulnerable to failure whereas larger taper junctions commonly used in revision modular femoral component designs have greater opportunity for success. Modular junctions of CoCr alloy on conventional Ti alloy have been shown to have a greater incidence of clinically significant mechanically assisted crevice corrosion and adverse reaction. Designs that have proven clinical strength and utility universally have larger, more robust junctions, that extend into the metaphysis of the femur. While these designs are primarily designed for revision total hip replacement (THR), they are occasionally indicated for primary THR. Overall, however, while design options at the neck-stem junction have unmatched clinical utility, no design that does not extend into the metaphysis has proven to be universally reliable. While routine use of modular neck components for primary THR does not appear to be clinically indicated based on current evidence, modular designs with proven successful proximal junctions appear to be indicated for revision THR and rare primary THR with extreme version or other anatomical circumstances.

Introduction

Bundled budgeting of payments for joint replacement services has become increasing common in an effort to improve quality while lowering cost. In the US, some Medicare bundled payment programs are voluntary whereas some now are mandatory. Large medical care and medical management organizations have largely been assigned or seized control of management of these programs, leaving the surgeon in a subordinate role. The current abstract describes an experience where surgeons provide leadership and accept responsibility in bundled payment program.

Introduction

While total hip arthroplasty is considered to be one of the most cost-effective medical interventions, the total cost of care for a population patients treated by THR can present a significant burden on the payer, whether it be an employer, private insurer or government. Data on the true cost of care has rarely been made available to the treating physician. Such lack of information makes comprehensive management difficult. Bundled payment models of care require knowledge of all costs associated with the care of our patients and opens new opportunity for analysis to improve management and outcomes. The current study assess the influence of surgical technique on total cost of care for total hip arthroplasty.

BACKGROUND

Ideal treatment of displaced femoral neck fragility fractures in the previously ambulatory patient remains controversial. Treating these patients with total hip arthroplasty has improved patient reported outcomes and reduced rates of revision surgery compared to those treated with hemiarthroplasty. However, possible increased risk of dislocation remains a concern with total hip arthroplasty.

The anterolateral and direct anterior approaches to total hip replacement have been applied in the femoral neck fracture population to minimize dislocation rates. However, the anterolateral approach has been associated with abductor injury and increased rates of heterotopic ossification while the anterior approach has been associated with peri-prosthetic femur fracture, lateral femoral cutaneous nerve injury, and wound complications. The Supercapsular Percutaneously Assisted (SuperPATH) approach was developed to minimize disruption of the capsule and short-external rotators in an effort to reduce the risk of dislocation and assist in quicker recovery in the elective hip arthroplasty setting. To achieve this, the SuperPATH technique allows the femur to be prepared in situ and the acetabulum to be reamed percutaneously once the femoral head is removed.

This study investigates the post-operative time to ambulation, length of stay, discharge destination, and early dislocation rate of previously ambulatory patients with a displaced femoral neck fragility fracture that were treated with a total hip arthroplasty via the SuperPATH technique.

Introduction

Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago1. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation by comparing the orientation of acetabular components revised due to recurrent instability and to a series of stable hip replacements.

Introduction

Navigation of acetabular component orientation is still not commonly performed despite repeated studies that show that more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned¹. The current study uses postoperative CT to assess the accuracy of a smart mechanical navigation instrument system for cup alignment.

INTRODUCTION

Patients less than 60 years old have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population.

Distal neck modularity places a modular connection at a mechanically critical location which is also the location that confers perhaps the greatest clinical utility. Assessment of femoral anteversion in 342 of our total hip replacement (THR) patients by CT showed a range from −24 to 61 degrees. The use of monoblock stems in some of these deformed femurs therefore must result in a failure to appropriately reconstruct the hip and have increased risks of impingement, instability, accelerated bearing wear or fracture, and adverse local tissue reaction (ALTR). However, the risks of failing to properly reconstruct the hip without neck modularity must be weighed against the additional risks introduced by neck modularity.

There are several critical design, material, and technique variables that are directly associated with higher or lower incidences of problems associated with modular neck femoral components. Unfortunately, in vitro testing of the fatigue strength of these constructs has failed to predict their behavior in vivo. Designs predicted to tolerate loads that far exceed those experienced in vivo still fail at unacceptably high rates. Titanium alloy neck components subjected to the stresses at the neck-stem junction continue to fail at an unacceptable incidence. CoCr alloy neck components, while theoretically stronger, still fracture and are further compromised by mechanically assisted crevice corrosion, metal hypersensitivity, and rarely, adverse tissue reaction.

Designs that have proven clinical strength and utility universally have larger, more robust junctions that extend into the metaphysis of the femur. While these designs are primarily designed for revision THR, they are occasionally indicated for primary THR. Overall, however, while design options at the neck-stem junction have unmatched clinical utility, no design that does not extend into the metaphysis has proven to be universally reliable. While routine use for primary THR does not appear clinically indicated based on current evidence, modular designs with proven successful proximal junctions appear to be indicated for extreme version or anatomical circumstances.

Acetabular component malalignment remains the single greatest root cause for revision THA with malposition of at least half of all acetabular components placed using conventional methods. These studies repeatedly document that the concept of using local anatomical landmarks has no scientific basis over a breadth of presenting pathology. Traditional navigation and robotics can potentially lead to improved component placement but these technologies have not gained widespread use due to the increase in time of use, complexity, and cost of these systems. Robotic systems have also proven to be potentially hazardous and inaccurate in routine clinical use. The alternative of placing the cup in the supine position, even with the use of arthroscopy, has been proven to have an incidence of inaccuracy equal or greater than that in the lateral position.

A smart mechanical instrument system was developed to quickly and easily achieve accurate cup alignment (HipXpert System, Surgical Planning Associates, Boston, MA). The system is based on a low dose, low cost CT study and a customised patient-specific surgery plan. The laterally-based system docks on a patient-specific basis with 3 legs: one through the incision behind the posterior rim, one percutaneously on the lateral side of the ASIS, and a third percutaneously on the surface of the ilium. A direction indicator on the top of the instrument points in the desired cup orientation. The anteriorly-based system also docks on a patient-specific basis with one leg on the anterior ischium and one leg on each ASIS, either to skin or to bone.

The lateral system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases and an independent study showing accurate cup placement in 98% of cases for both anteversion and inclination. This compares to a recent study of robotic methods that 88% of inclination and 84% for anteversion.

Smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problem of acetabular component malorientation.

Management of recurrent instability of the hip requires careful assessment to determine any identifiable causative factors. While plain radiographs can give a general impression, CT is the best methodology for objective measurement. Variables that can be measured include: prosthetic femoral anteversion, comparison to contralateral native femoral anteversion, total offset from the medial wall of the pelvis to the lateral side of the greater trochanter, comparison to total offset on the contralateral side, acetabular inclination, & acetabular anteversion.

Wera et al describe potential causes of instability. These are typed into I. Acetabular Component Malposition; II. Femoral Component Malposition; III. Abductor Deficiency; IV. Impingement; V. Late Wear; and VI. Unknown.

Acetabular component malposition is the most common cause of instability and so measurement of cup orientation is essential. It is well known that excessive or inadequate anteversion can lead to anterior and posterior dislocation respectively but horizontal components are also associated with posterior dislocation due to deficient posterior/inferior acetabular surface.

Similarly, excessive or inadequate femoral anteversion can be easily identified on CT as can insufficient total offset of the reconstructed joint compared to the contralateral side. This can be caused by medialization of the acetabular component.

Abductor deficiency can be a soft-tissue cause of instability, but it certainly isn't the only one. Knowledge of the prior surgical exposure can be instructive. Anterior exposures can be prone to deficient anterior capsule just as posterior exposures can be prone to deficient posterior capsule and short rotators, while anterolateral and lateral exposures can be associated with gluteus minimus and gluteus medius compromise.

Impingement, whether involving implants, bone, or soft tissue are primarily secondary to the above factors, if osteophytes were properly trimmed at the index procedure.

Correction of the incorrect variables is the primary goal of revision for instability and greatly preferable to using salvage options such as dual-mobility or constrained articulations which invoke additional concerns. Ultimately though, such salvage options are necessary if the cause of the instability cannot be determined or can be determined but not corrected. Bracing, while highly inconvenient and sometimes impractical for certain patients, still has a role in specific circumstances. Formal analysis of the unstable prosthetic reconstruction is the key to successful treatment.

Precision planning with correct sizing and placement of components is critical to proper execution of total hip arthroplasty. While the desire to achieve excellent outcomes has always been a surgeon's goal, value-based care programs such as the Comprehensive Joint Replacement (CJR) program apportion real expenditures for the cost of treating complications such as fracture or dislocation to the participants. Such accountability accentuates the importance of optimizing the planning and execution of joint replacement surgery. Acetabular component sizing and placement in particular remains the single greatest challenge to surgeons. This is simply due to the fact that the requisite spatial information is not available to the surgeon during conventional surgery. Basing component placement on local anatomical landmarks without knowing the patient-specific nature of those landmarks ensures poor component placement in many cases. As a result, studies demonstrate that at least ½ of all acetabular components placed using conventional methods are malpositioned.

Potential solutions include the using of intra-operative radiographic analysis, traditional navigation and robotics. Unfortunately, measurements of plain radiographs have repeatedly been shown to be inaccurate due to lack of knowledge of and correction for beam center location, magnification, beam divergence, and position of the pelvis itself on the image. As a result, such quantification of unquantifiable images can systematically lead to poor decisions. Intra-operative radiograph measurement methods have been shown to lead to anteversion measurement errors as high as 27 degrees. Similarly, there is a perception that performing total hip arthroplasty through the anterior exposure can result in reliable cup positioning when fluoroscopy is used, but such procedures have also been shown to have a high incidence of cup malposition.

Image-free navigation, image-based navigation, and image-based robotics can potentially lead to accurate component placement. Adoption of these technologies, however, has been limited, possibly due to the increase in time of use, complexity, and cost of these systems. Robotic systems have also proven to be potentially hazardous and inaccurate in routine clinical use. A cloud-based, patient-specific hip surgery planning and smart-tool cup navigation system was developed to address the most common technical problems affecting hip arthroplasty (HipXpert System, Surgical Planning Associates, Boston, MA). The methodology provides the surgeon with a full 3D plan of the surgery including cup size, cup orientation, stem size, head length, femoral anteversion, and planned change in leg length and offset. The application controlling the plan allows the surgeon to instantly change the plan and shows the implants in both 3D and on multiplanar cross-sectional views. The associated smart tool is adjusted specifically for that patient and when docked, provides orientation information to the surgeon.

The system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases including by an independent study. This compares to a recent study of robotic methods that measured 88% for inclination and 84% for anteversion.

Cloud-based 3D planning combined with smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problems of acetabular component malorientation and provides critical pre-operative information including acetabular and femoral component sizes, planned femoral anteversion, and planned changes in leg length and offset of the surgery.

Introduction

Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. The current study assesses the validity of intraoperative assessment using a specialized software to analyze intraoperative radiographs.

INTRODUCTION

Evolving payment models create new opportunities for assessment of patient care based on total cost over a defined period of time. These models allow for analyses of economic data that was previously unavailable and well beyond our familiar studies which typically include length of stay, surgical complications, and post-operative clinical and radiographic assessments. In the United States, the new Federal program entitled TheBundled Payment for Care Initiative created new opportunities for the assessment of surgical interventions. The purpose of the reported study was to assess the total reimbursement for care as a function of surgical technique in primary total hip arthroplasty (THA).

Introduction

Navigation of acetabular component orientation is still not commonly performed despite repeated studies that show that more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned1. The current study uses postoperative CT to assess the accuracy of a smart mechanical navigation instrument system for cup alignment.

INTRODUCTION

Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago¹. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation by comparing the orientation of acetabular components revised due to recurrent instability and to a series of stable hip replacements.

BACKGROUND

Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation.

Introduction

Studies show that cup malpositioning using conventional techniques occurs in 50 to 74% of cases defined. Assessment of the utility of improved methods of placing acetabular components depends upon the accuracy of the method of measuring component positioning postoperatively. The current study reports on our preliminary experience assessing the accuracy of EOS images and application specific software to assess cup orientation as compared to CT.

INTRODUCTION

Young patients (< 50 years old) have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population.

Introduction

Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. A recent study measuring cup orientation on conventional radiodiographs demonstrated an incidence of cup malpositioning of 50% according to the safe zone that they defined 1,2. A prior study of 105 conventionally placed cups using CT demonstrated a cup malpositioning incidence of 74%3. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT.

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. The earlier PAO series show 20 year survivorship of 81% and 65% in Tonnis Grade 0 and 1 hips.

Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-operatively whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis.

Acetabular component malalignment remains the single greatest root cause for revision THA with malposition of at least ½ of all acetabular components placed using conventional methods. The use of local anatomical landmarks has repeatedly proven to be unreliable due to individual variation of these structures. As a result, the use of such landmarks without knowledge of their three-dimensional orientation may actually be a major cause of component malpositioning. Traditional navigation and robotics can potentially lead to improved component placement but these technologies have not gained widespread use due to the increase in time of use, complexity, and cost of these systems. The alternative of placing the cup in the supine position, even with the use of arthroscopy, has been proven to have an incidence of inaccuracy equal or greater than that in the lateral position.

A smart mechanical instrument system was developed to quickly and easily achieve accurate cup alignment (HipXpert System, Surgical Planning Associates, Boston, MA). The system is based on a low dose, low cost CT study and a customised patient-specific surgery plan. The laterally-based system docks on a patient-specific basis with 3 legs: one through the incision behind the posterior rim, one percutaneously on the lateral side of the ASIS, and a third percutaneously on the surface of the ilium. A direction indicator on the top of the instrument points in the desired cup orientation. The anteriorly-based system also docks on a patient-specific basis with one leg on the anterior ischium and one leg on each ASIS, either to skin or to bone.

The lateral system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases and an independent study showing accurate cup placement in 98% of cases for both anteversion and inclination. This compares to a recent study of robotic methods with 88% for inclination and 84% for anteversion.

Smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problem of acetabular component malorientation.

Properly designed ceramic-on-ceramic total hip arthroplasty has consistently shown excellent clinical outcomes without the problems associated with crosslinked polyethylene bearings such as liner dissociation, debris associated osteolysis, polyethylene fracture, clinically measurable wear, and taper-corrosion associated adverse tissue reaction when metal heads are used. The recognition of these results has been affected by the confusion with the poorer results of designs with elevated metal rims especially when coupled with the use of femoral components made of beta-titanium alloys. Our clinical experience, now at 18 years, with flush mounted liners and Ti-Al6-V4 stem and cup alloy demonstrate consistently excellent outcomes without osteolysis or ALTR. Ceramic-Ceramic THA remains the gold standard for the young active patient.

Background

Stratifying patients with Low Back Pain (LBP) using the STarT Back Tool and delivering targeted treatment has demonstrated efficacy in individual physiotherapy settings. Physiotherapy interventions for LBP patients are often delivered in groups. This study aimed to explore the sustainability and cost effectiveness of a group stratified intervention in primary care.

Several design principles were considered paramount when the surgical technique of performing total hip arthroplasty through an incision in the superior capsule without dislocation of the hip joint was developed. These design principles include: Preservation of the abductors; Preservation of the posterior capsule and short external rotators; Preparation of the femur in situ without dislocation of the hip; In-line access to the femoral shaft axis; Ability to perform a trial reduction; Independence from intraoperative imaging; Independence from a traction table; Applicable to at least 99% of THA procedures

Personal experience with more than 1950 THA using the superior capsulotomy technique over a 12-year period has demonstrated several observations: Dislocation rate of 0.15% (3 in 1950); Acute deep infection rate of 0% (0 in 1950); Universal applicability: used in 99.7% of primary THA; Lateral femoral cutaneous nerve palsy incidence: 0/1950; Femoral nerve palsy incidence: 0/1950; Transient peroneal palsy incidence: 2/1950; Length of stay (since 2010): 1.55 days; Discharge to home: 98%; 90-day cost (2/13 to 2/14) compared to other exposures in CMS patients in the same institution: $24,200 vs $30,100; Readmission costs (CMS 2/13 to 2/14) at 90 days: $0.

Conclusion: Performing total hip arthroplasty without dislocation and with preservation of the abductors, posterior capsule and short external rotations has proven to have a low dislocation rate, a low infection rate, and wide applicability. CMS 12-month expenditure data documenting ZERO dollars spent on readmission for any reason within 90 days of surgery demonstrates the potential for simultaneously improving incomes and reducing cost, with particular benefit within the CMS BPCI and private bundled payment programs.

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Preoperative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces.

Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctible problems prior to the development of significant secondary arthrosis.

Acetabular component malalignment remains the single greatest root cause for revision THA with malposition of at least ½ of all acetabular components placed using conventional methods. The use of local anatomical landmarks has repeatedly proven to be unreliable due to individual variation of these structures. As a result, the use of such landmarks without knowledge of their three-dimensional orientation may actually be a major cause of component malpositioning. Traditional navigation and robotics can potentially lead to improved component placement but these technologies have not gained widespread use due to the increase in time of use, complexity, and cost of these systems. The alternative of placing the cup in the supine position, even with the use of arthroscopy, has been proven to have an incidence of inaccuracy equal or greater than that in the lateral position.

A smart mechanical instrument system was developed to quickly and easily achieve accurate cup alignment (HipXpert System, Surgical Planning Associates, Boston, MA). The system is based on a low dose, low cost CT study and a customised patient-specific surgery plan. The laterally-based system docks on a patient-specific basis with 3 legs: one through the incision behind the posterior rim, one percutaneously on the lateral side of the ASIS, and a third percutaneously on the surface of the ilium. A direction indicator on the top of the instrument points in the desired cup orientation. The anteriorly-based system also docks on a patient-specific basis with one leg on the anterior ischium and one leg on each ASIS, either to skin or to bone.

The lateral system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases and an independent study showing accurate cup placement in 98% of cases. The newer anterior system has the potential for even greater accuracy.

Smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problem of acetabular component malorientation.

Surgical invention to preserve the native hip joint remains a preferred treatment option for hips in young patients with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The two most common pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement, if present. Correction of deformities on the femoral side is now less common and reserved for only the more severe combined femoral and acetabular dysplasias or the rare isolated femoral dysplasia. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces.

Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-op whereas dysplastic hips can become symptomatic with the onset of instability in the absence of significant secondary arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming.

Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis.

While crosslinked polyethylene has reduced the rate of wear and osteolysis in THA, osteolysis still occurs and taper-corrosion induced wear has become recognised as an increasing problem especially when larger diameter metal bearings are used. Long-term follow up studies of newer polyethylene bearings continue to lag those of ceramic-on-ceramic bearings by several years.

Ceramic-on-ceramic (CoC) bearing surfaces have consistently demonstrated reliable clinical results with when coupled with appropriated designed femoral stems and acetabular shells and have been shown to exhibit virtually no risk of adverse biologic reaction. Further, CoC bearings have not been associated with corrosion-induced adverse tissue reactions that occur with metal taper junctions.

Revisions for squeaking have been associated with specific designs and materials, including the use of a titanium elevated metal rim on the acetabular side, and more flexible femoral components made of a beta-titanium alloy (TMZF) which had thin necks and relatively small tapers.

Multiple clinical studies document excellent long-term survival of CoC bearing couples in young patients with revision for any reason as the primary endpoint. Our own experience with 341 hips in patients under 50 with 2–15 years and average 9.1-year follow up demonstrates a 95% overall survivorship (revision for any reason) at 13 years.

CoC bearings continue to show excellent durability in young, high demand patients with an absence of osteolysis in any case. CoC bearings continue to represent an excellent alternative to bearing couples containing polyethylene.

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces.

Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming.

Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis.

Ceramic-on-ceramic (COC) bearing surfaces have consistently demonstrated reliable clinical results with when coupled with appropriated designed femoral stems and acetabular shells. Ceramic bearing surfaces are highly wettable and display both boundary and hydrodynamic fluid-film lubrication modes, which lead to extremely low wear rates. Furthermore, COC bearing couples have been shown to exhibit virtually no risk of adverse biologic reaction and have not been associated with corrosion-induced adverse tissue reactions that occur with metal taper junctions, particularly head-neck taper junctions. The relative brittleness of ceramics initially was thought to be a major disadvantage; however, four decades of improvement in the manufacture of ceramics and rigorous proof testing has led an extremely low risk of fracture, perhaps lower than that for cross-linked polyethylene. More recently it has become increasing appreciated that nearly all revisions for squeaking have been restricted to specific designs and materials, including the use of a titanium elevated metal rim on the acetabular side, and more flexible femoral components made of a beta-titanium alloy (TMZF) which had thin necks and relative small tapers. Multiple clinical studies document excellent long-term survival of COC bearing couples in young patients with revision for any reason as the primary endpoint. Our own experience with 341 hips with 2 to 15 and average 9.1 year f/u demonstrates a 95% overall survivorship (revision for any reason) at 13 years in patients under 50 years of age at the time of surgery.

By contrast, cross-linked polyethylene bearings have not been studied so carefully and have not been shown to be superior to ceramic-ceramic bearings in young patients. These bearing surfaces represent a very heterogeneous group of products, with varying degrees of cross-linking, post-irradiation processing methods, and additives. Cross-linked polyethylenes in general have a lower fatigue strength than conventional polyethylene and are prone to fracture, especially when thin material is subjected to high stress. Some types of cross-linked polyethylenes are prone to in vivo oxidation, leading to further mechanical compromise over time. Studies also demonstrate the absence of reduction in femoral head penetration or risk of osteolysis in heads 32mm and larger, which are commonly used today. The most recent cross-linked polyethylene products have the least clinical support for their use. The long-term biologic effects of the smaller HXLPE wear particles and newer additives, including the more recently added vitamin E compounds are unknown. Indeed, in vitro, the debris has been shown to be cytotoxic. There is a paucity of survivorship data for hips utilising HXLPE, especially in younger, more active individuals. For these reasons, we believe that the ceramic-ceramic bearings are the gold standard for THA in the young patient and that cross-linked polyethylene bearing are being continually changed and have little long term clinical outcomes data to support their use.

Introduction:

Cup malposition leads to increased incidences of dislocation, impingement, wear, and revision. The HipSextant navigation system is a smart mechanical navigation device designed to indicate correct cup orientation at surgery. The current study assesses the effect of deliberately mis-docking the device on clinical accuracy.

Introduction:

Wear, wear-associated osteolysis, and instability are the most common reasons for revision total hip arthroplasty. These failures have been shown to be associated with acetabular component malpositioning. However, optimal acetabular component orientation on a patient-specific basis is currently unknown. The current study uses CT to assess acetabular orientation in a group of unstable hips as compared to a control group of stable hips.

Introduction:

Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. A recent study measuring cup orientation on conventional radiodiographs demonstrated an incidence of cup malpositioning of 50% according to the safe zone that they defined^1,2. A prior study of 105 conventionally placed cups using CT demonstrated a cup malpositioning incidence of 74%³. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT.

Background:

While more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned, traditional surgical navigation and robotoics have not been widely adopted. This may be due to the additional time, expense, and complexity associated with this technology. As an alternative, smart mechanical navigation instruments, adjusted on a patient-specific basis, have been introduced to address the problem of cup malorientation. The current study assesses the accuracy of acetabular component alignment using a mechanical navigation instrument.

Introduction:

Conventional methods of aligning the acetabular component during hip arthroplasty and hip resurfacing often rely upon anatomic information available to the surgeon. Such anatomical information includes the transverse acetabular ligament and the locations of the pubis, ischium and ilium. The current study assesses the variation in orientation of the plane defined by the pubis, ischium and ilium on a patient-specific basis as measured by CT.

Introduction

Adverse Local Tissue Reactions (ALTR) have been reported in association with both wear and corrosion. Tissue reactions have been reported in association with corrosion at CoCr head-CoCr neck, CoCr head-TiAl6V4 neck, and CoCr modular neck on beta-titanium (TMZF) stem junctions. The current abstract reports on 3 cases of ALTR in association with CoCr modular necks on convention titanium (TiAl6V4) stem junctions.

Case 1. A 67 year old male (87 kg, 1.73 m, BMI 29.1) presented with new onset hip irritation 11 months after surgery. Radiographs show no abnormalities. Further investigation revealed the following: ESR = 95, CRP = 5, Cr level = 1.0, Co level = 4.1, leukocyte transformation testing = highly reactive to nickel. Hip aspiration was culture negative with 11,250 wbc. Metal artifact reduction MR showed cystic local reaction in the region of the greater trochanter.

Case 2. A 52 year old male (89 kg, 1.83 m, BMI 26.5) presented with new onset hip irritation 30 months after surgery. Radiographs show no abnormalities. Further investigation revealed the following: ESR = 7, CRP = 5.4, Cr level = 2.1, Co level = 4.8, leukocyte transformation testing = reactive to nickel. Hip aspiration was culture negative with 3995 wbc. Metal artifact reduction MR showed cystic local reaction in the region of the iliopsoas.

Case 3. A 52 year old male (104 kg, 1.85 m, BMI 30.1) presented with new onset hip irritation 26 months after surgery. Radiographs show no abnormalities. Further investigation revealed the following: ESR = 33, CRP = 34.9, Cr level = 1.0, Co level = 3.7, leukocyte transformation testing = no reactivity to any of the biomaterials. Hip aspiration was culture negative with 3,780 wbc. Metal artifact reduction MR showed cystic local reaction in the region of the iliopsoas.

Introduction:

Young patients have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older cohorts, possibly to due higher activity and a higher incidence of deformity and prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population.

Introduction

Conventional methods of aligning the acetabular component during hip arthroplasty and hip resurfacing often rely upon anatomic information available to the surgeon. Such anatomical information includes the transverse acetabular ligament and the locations of the pubis, ischium and ilium. The current study assesses the variation in orientation of the plane defined by the pubis, ischium and ilium on a patient-specific basis as measured by CT.