This review aims to explore the methodologies used for estimating the direct and indirect costs attributed to back pain in developed countries. Six databases were searched to uncover studies about the direct and indirect costs of back pain published in English upto November 2016. Data extracted included study characteristics, cost categories and analysis methods. Results were synthesised descriptively.Purpose
Methods
To investigate whether the duration of pain has an influence on the clinical outcomes of patients with low back pain (LBP) managed through the North East of England Regional Back Pain and Radicular Pain Pathway (NERBPP). The NERBPP is a clinical pathway based upon NICE guidelines (2009) for LBP. Patients with LBP referred onto the NERBPP by their General Practitioner (GP) between May 2015 and January 2017 were included in this evaluation. Data from 635 patients, who provided pre and post data for pain (Numerical rating scale [NRS]), function (Oswestry Disability Index [ODI]) and quality-of-life (EuroQol [EQ5D]), were analysed using a series of covariate adjusted models in SPSS. Patients were categorised into four groups based upon pain duration: <3months, ≥3 to <6months, ≥6months to <12months, ≥12months.Aims
Patients and Methods
The study sought to determine the results of labral restoration among patients over age 60 compared to a cohort of younger adults. 21 consecutive patients over age 60 undergoing labral repair with minimum one-year follow-up were compared to a contemporaneous group of 21 patients age 18–55 matched for gender, degree of chondral damage, and associated FAI or dysplasia. Follow-up averaged 18.9 months (12 to 24 months). The study group averaged 63.2 years (61 to 71); with 20 FAI and one dysplasia. 19 had acetabular articular damage (2 grade IV, 11 grade III, 5 grade II, 1 grade I) and 6 had femoral changes (1 grade IV, 5 grade 3). The control group averaged 35.8 years (20 to 54). Average improvement among the study group was 28.1 points modified Harris Hip Score (mHHS) and 37.5 points iHOT; and among the control group, 21.2 points mHHS and 37.1 points iHOT. There was no statistically significant difference between the two groups in the amount of improvement, with statistically and clinically significant improvement noted in both. Two study group patients underwent total hip arthroplasty (THA) at average 10 months with one control group THA at 11 months. All three converted to THA had combined grade IV acetabular and grade III femoral damage. There were no repeat arthroscopies and no complications in either group. We conclude that patients over age 60 can benefit from arthroscopic labral repair with improved outcomes, modest rates of conversion to THA, and small risk of complication. Results are comparable to younger adults. Combined bipolar grade IV or grade III articular damage is a harbinger of conversion to THA, regardless of age.
The pelvis is known to undergo significant movement during Total Hip Replacement (THR). We developed a 4D-tracking device employing an inertial measurement unit (IMU) to track changes in pelvic orientation during THR. The IMU was mounted on the iliac crest in 39 cases with tracking initiated at the commencement of surgery and digital logging of significant intra-operative milestones (i.e. acetabular impaction). The system was validated by videoing a select number of cases and the 4D model linked in real-time. Data were processed using a custom Java-based infrastructure to calculate roll (left/right) and tilt (flexion/extension). 19 patients underwent direct anterior approach (DAA) and 20 posterior approach (PA). Comparing DAA to PA, at acetabular impaction there was mean pelvic roll seen of 3.7°(range 0.5–10.1°) in the DAA group, and 5.6°(range 0.1–16.2°) in the PA group. Mean tilt in the DAA group was 3.7°(range: 0.2–7.1°) and in the PA group was 1.7°(range: 0.2–4.3°). Mean BMI in the DAA group was 25.2(range: 18.4–34.2) and 29.1(range: 21.5–42.4). There was no direct correlation between BMI and the amount of roll or tilt recorded for individual patients. The IMU tracking device provided a useful and real-time method of assessing pelvic orientation during THR via both the DAA and posterior approach. Specific variations in tilt and roll are consistent with previous literature. Significant variation in the pattern of pelvic movement was noted to be dependent on the approach and the position of the patient on the operating table.
The aim of this study was to determine whether patients with
metal-on-metal (MoM) arthroplasties of the hip have an increased
risk of cardiac failure compared with those with alternative types
of arthroplasties (non-MoM). A linkage study between the National Joint Registry, Hospital
Episodes Statistics and records of the Office for National Statistics
on deaths was undertaken. Patients who underwent elective total
hip arthroplasty between January 2003 and December 2014 with no
past history of cardiac failure were included and stratified as
having either a MoM (n = 53 529) or a non-MoM (n = 482 247) arthroplasty.
The primary outcome measure was the time to an admission to hospital
for cardiac failure or death. Analysis was carried out using data
from all patients and from those matched by propensity score.Aims
Patients and Methods
Osteosynthesis to conserve femoral head following neck of femur (NOF) fractures has reported failure rates of 36 to 47% at 2 years. However, the long-term outcomes of THAs performed for failed osteosynthesis is yet to be elucidated. This study aims to report on long term outcome of primary THAs post failed osteosynthesis for NOF fracture. Consecutive patients with THA for failed NOF osteosynthesis managed by a single unit between January 1974 and December 2009 were included. Clinical and radiological outcomes of all 72 patients were analysed. Patients with minimum follow-up of 5 years were included. Those with less than 5 years of follow-up were reviewed for failures.Introduction
Methods
The ideal operative treatment of displaced sub capital femoral fractures in the elderly is controversial. Recently, randomised controlled trials have suggested a better outcome with the use of total hip arthroplasty (THA) to treat displaced intra capsular fractures of the femur for elderly patients in good health. More recently the concept of dual mobility cups is being promoted to avoid dislocations in this cohort of patients. However, overall there is limited evidence to support the choice between different types of arthroplasty. Dislocation remains a main concern with THA, especially when a posterior approach is used. We analysed the outcome of 115 primary THR (112 cements and 3 uncemented) THR using a posterior approach with soft tissue repair in active elderly patients presenting with displaced intra capsular femoral neck fractures. Size 28 mm head was used in 108 and a size 32 mm head in the rest. All surgery was performed by specialist hip surgeons. Satisfactory results were noted in terms of pain control, return to pre-morbid activity and radiological evidence of bone implant osteo-integration. The 30-day mortality was nil. There were two dislocations and only one needed revision surgery due to recurrent dislocation. In conclusion, with optimal patient selection, THA seems to provide a good functional outcome and pain relief in the management of displaced intracapsular femoral neck fractures. Excellent outcome can be achieved when done well using the standard cemented THR and with 28mm head. A good soft tissue repair and a specialist hip surgeon is preferable.
Prosthetic joint infection continues to remain a diagnostic challenge for unhappy primary arthroplasty of hip and knees. There is increasing dependence upon alpha-defensin test to make key decisions like whether to revise or not & to decide between one-stage versus two-stage. This study aims to assess diagnostic accuracy of alpha-defensin test in determining prosthetic hip & knee infection and to provide guidance for appropriate use of this novel but expensive investigation. Retrospective review of all alpha-defensin investigated patients in an orthopaedic institute between February 2015 & March 2017 was performed. Clinical and radiological outcomes including re-infections, re-operations were analysed and alpha-defensin outcomes were compared with that of other available investigations.Aim
Methods
Conservative treatment of acute AT ruptures with functional rehabilitation has demonstrated superior results with equal reported re-rupture rates but without the added complications of surgical treatment. There is no consensus on the duration and method of treatment using functional rehabilitation regimes. The purpose of this paper is to define our treatment regime, the Leicester Achilles Management Protocol (LAMP), supported with patient reported outcomes and objective measures of assessment. All patients with an acute achilles tendon rupture were treated with the same non-operative LAMP functional rehabilitation regime in a VACOped boot for 8 weeks. 12 months post rupture ATRS scores and objective measures of calf muscle girth and heel raise height were obtained and analysed. Venous thromboembolic rates and rates of re-rupture were recorded.Background
Methods
One of the major concerns of hinge knees have been reported in literature is mechanical failure. Failure in the form of component fracture (2–10%) and hinge dislocation/ failure are worrisome. In addition, higher risk of aseptic loosening with hinge knee prosthesis has been attributed to stress transfer at bone cement interface. Retrospective review of clinical and radiological results of 71 consecutive patients operated at single centre using Smiles hinge knee (Stanmore implants) between 2010 and 2014. Data was collected till the latest follow up. Mechanical failure due to any reason was considered as primary end point. Radiological evidence of aseptic loosening was considered to be one of the surrogate end points.Background
Methods
This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group. A total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery.Objectives
Methods
Dislocation and instability remain leading cause of failure following THA. We present a single-surgeon 10-year experience with use of Dual Mobility (DM) bearings in Primary and Revision THA using posterior approach. 127 DM bearings were implanted between September 2006 – September 2016; 102 in high-risk primary THA's and 25 revision THA's for either treatment or prevention of instability. Selection for DM bearing followed individual patient risk assessment. Criteria for use of DM bearing were presence of multiple risk factors. Mean age was 72.9 years. 100 Mono-block DM implants, 22 Modular DM implants and 5 custom-made DM devices were implanted. Revision cohort included those used in conjunction with a cage or porous metal augments. 2 dislocations (1.6%) were observed, both in the Revision group, 1 was recurrent requiring revision to constrained liner. Primary group had 2 revisions; 1 peri-prosthetic fracture and 1 deep infection. No DM bearing specific complications were observed. A constructed life table calculated survival function with endpoint set as revision for any reason demonstrated a cumulative survival of 94% at 7.4 years. In high-risk patients, DM bearings are successful at preventing and treating dislocation in THA. Primary cohort in this study all had multiple risk factors for instability but no dislocations or bearing specific complications were observed. Dislocations observed in Revision group were associated with major soft tissue deficiency. This study adds to the promising results already reported with DM THA articulations and should be considered for patients at risk of dislocation or instability. Runner Up – Best Paper Award
The US obesity epidemic has transcended into the arthroplasty patient population and surgeons must assess whether obesity is a risk factor for poor outcomes in total joint arthroplasty (TJA) and determine how it should be managed in order to insure good clinical outcomes. In the United States, 34.9% of adults are currently obese (BMI > 30). In a recent study, 54.5% of patients reporting to arthroplasty clinics in the US were obese. We performed a recent literature review to determine how obesity impacts outcomes in total hip and knee arthroplasty and what must be done to improve outcomes in the obese arthroplasty patient. We know that obesity and its associated comorbid conditions do have worse outcomes and increased complications in TJA patients. We also know that complications proportionately increase with increasing severity of obesity. The super-obese population is at the greatest risk of complication following TJA and pre-operative screening and management is essential in reducing complications. Although weight loss is important, our bariatric data has shown that it does not solve the problem of obesity in itself and the patient's metabolic state is likely a more important issue. Implant selection is important and strong consideration should be given to avoiding direct anterior approach in the THA obese patient. Understanding of obesity specific complications and treatment options is crucial for patient counseling and optimisation to ensure successful treatment in obese TJA patients.
TKA is one of the most common orthopaedic operations performed worldwide and it is largely successful in pain relief and functional recovery. However, when pain persists post-operatively the thorough evaluation must be instituted. Extra-articular causes of knee pain include; hip pathology, lumbar spine degenerative disease or radicular symptoms, focal neuropathy, vascular disease, and chronic regional pain syndrome. Intra-articular causes of knee pain: infection, crepitation/ clunk, patella osteonecrosis, patella mal-tracking, soft tissue imbalance, malalignment, arthrofibrosis, component loosening, implant wear, ilio-tibial band irritation, and bursitis. Other causes of pain to rule out are component overhang with soft tissue irritation, recurrent hemarthrosis secondary to synovial impingement or entrapment, non-resurfaced patella, and metal sensitivity. A careful history may reveal previous knee surgeries with delayed healing or prolonged drainage, chronology of sign and symptoms, co-morbid medical conditions, jewel or metal sensitivity. Physical exam should help with specific signs in the operated knee. Targeted local anesthetic blocks are helpful and response to lumbar sympathetic blocks determines presence of CRPS. Lab tests are important: ESR, CRP, WBC, aspiration with manual cell count and diff, leukocyte esterase dipstick, RA titers, metal derm patch testing, nuclear scans, CT best for rotational malalignment,, and MARS MRI. More recently patient satisfaction as an outcome measure has shown TKA results not satisfactory in 11 – 18% of patients. A discordance of patient vs. surgeon satisfaction exists so the following factors may help improve this: correct patient selection, establishing and correlating surgeon-patient expectations, peri-operative optimisation of patient comorbidities to help avoid preventable complications, use of pre- and post-operative pathways. Satisfaction rates can best be improved by addressing the previous points with patients prior to TKA surgery.
We used the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) to investigate the risk of revision due to prosthetic joint infection (PJI) for patients undergoing primary and revision hip arthroplasty, the changes in risk over time, and the overall burden created by PJI. We analysed revision total hip arthroplasties (THAs) performed due to a diagnosis of PJI and the linked index procedures recorded in the NJR between 2003 and 2014. The cohort analysed consisted of 623 253 index primary hip arthroplasties, 63 222 index revision hip arthroplasties and 7585 revision THAs performed due to a diagnosis of PJI. The prevalence, cumulative incidence functions and the burden of PJI (total procedures) were calculated. Overall linear trends were investigated with log-linear regression.Objectives
Methods
Synovasure has been designed and validated for use in the diagnosis of periprosthetic joint infection (PJI). It has a reported sensitivity of 97.4% (CI 86.1–99.6%) and specificity of 95.8% (CI 90.5–98.6%), higher than the variable results reported for aspiration by most units. At a cost of £500 per test, we aimed to establish cost-effectiveness and diagnostic accuracy, to determine its role in routine practice. We developed a protocol for pre-operative aspiration or intra-operative use. Prerequisites for entry were a high index of clinical suspicion for PJI and equivocal standard investigations. All cases were discussed at the lower limb arthroplasty MDT and approved only if use would change clinical management. Over 15 months, 36 tests were approved for 22 aspirations (5 hip, 17 knee) and 14 intra-operative cases (7 hip, 7 knee). 10/36 had undergone previous revision surgery. 35/36 cases complied with the protocol. All 22 Synovasure aspirations were negative, corresponding to the microbiology in all but one case; thought to be a contaminant. In the intra-operative group there was one true positive and 12 true negative tests, giving a sensitivity of 100% (95% CI 2.5–100%) and a specificity of 100% (95% CI 73.5–100%). Synovasure influenced decision making in 34/36 procedures. One test failed and in another there was evidence of frank infection. In 11 cases no surgery was performed versus a potential two-stage revision and in 21 cases a single rather than two-stage revision was performed. Resulting in estimated savings of £686,690, offset against a cost of £18,000. The Synovasure test was found to be sensitive and specific and can aid decision-making particularly in complex cases with an equivocal diagnosis of PJI. The use of this test through a robust protocol driven peer review MDT process not only reduces patient morbidity but drives significant efficiency savings.
Early intervention is advocated to prevent long-term work absence due to musculoskeletal (MSK) pain. The SWAP trial tested whether adding a vocational advice (VA) service to best current care led to fewer days work absence over 4 months. The SWAP trial was a cluster randomised controlled trial in 6 general practices, 3 randomised to best current care (control), 3 randomised to best current care and the VA service (intervention). Patients were ≥18 years, absent from work ≤6 months or struggling at work due to MSK pain. Primary outcome was number of days absent over 4 months. Exploratory subgroup analyses examined whether the effect was larger for patients with spinal pain compared to other MSK pain.Introduction
Methods
The stability of the elbow joint following an acute elbow dislocation is dependent on associated injuries. The ability to identify these concomitant injuries correctly directs management and improves the chances of a successful outcome. Interpretation of plain radiographs in the presence of either a dislocation or post-reduction films with plaster in-situ is difficult. This study aimed to assess the ability of orthopaedic registrars to accurately identify associated bony injuries on initial plain radiographs using CT as the gold standard for comparison. Patients over the age of 16 years undergoing an elbow CT scan within one week of a documented elbow dislocation between 1st June 2010 and 1st June 2014 were included in the study. Three orthopaedic registrars independently reviewed both the initial dislocation and immediate post reduction plain radiographs to identify any associated bony injuries. This radiograph review was repeated by each registrar after two weeks. The incidence of associated injuries as well as the inter- and intra-observer variability was calculated.Introduction
Methods
Since 2011, the knee service at the Nuffield Orthopaedic Centre has been offering a neutralising medial opening wedge high tibial osteotomy (HTO) to a group of patients presenting with early medial osteoarthritis of the knee, varus alignment and symptoms for more than 2 years. During development of this practice an association was observed between this phenotype of osteoarthritis and the presence of CAM deformity at the hip. A retrospective cohort study. All patients who underwent HTO since 2011 were identified (n=30). Comparator groups were used in order to establish whether meaningful observations were being made: Control group: The spouses of a high-risk osteoarthritis cohort recruited for a different study at our unit (n=20) Pre-arthroplasty group: Patients who have undergone uni-compartmental arthroplasty (UKA) for antero-medial osteoarthritis (n=20)All patients had standing bilateral full-length radiographs available for analysis using in house developed Matlab-based software for hip measurements and MediCAD for lower limb alignment measurements.Background
Methods
Frequency of primary total hip (THA) and total knee (TKA) arthroplasty procedures is increasing, with a subsequent rise in revision procedures. This study aims to describe timing and excess surgical mortality associated with revision THA and TKA compared to those on the waiting list. All patients from 2003–2013 in a single institution who underwent revision THA and TKA, or added to the waiting list for the same procedure were recorded. Mortality rates were calculated at cutoffs of 30- and 90-days post-operation or addition to the waiting list.Background
Methods
Functional restoration of patella kinematics is an essential component of TKA, whether the patella is replaced or not. This goal is accomplished by a multifactorial approach: establish proper component position and alignment, especially rotation; avoid IR of the femoral and ER of the tibial components; maintain correct joint line position; achieve symmetrical soft tissue balance. Most modern TKA designs have an anatomic trochlear groove shape to enable midline tracking. Patella implants are better designed as well with three equilateral lugs for fixation and either dome or anatomic shape. The apex of the patella component should be aligned with the apex of the patella raphe which is more medial than lateral. This method leaves an island of exposed lateral patella facet which is managed with the “lateral slat technique” to be described. It is essentially an intraosseous lateral release. The early mobilization of modern TKA patients demands watertight closure to prevent soft tissue attenuation and late tracking issues. When confronted with a patient with a laterally dislocated patella, implementation of the “lateral slat technique” should be done at the approach to obtain midline tracking. Such patients require a median parapatellar (MPP) approach and may need distal-lateral vastus medialis advancement (Insall procedure). Adherence to the principles iterated herein will produce a happy patient with good patello-femoral kinematics and function.
As the American population ages and a trend toward performing total hip arthroplasty (THA) in younger patients continues, the number of Americans undergoing THA is projected to increase over time. The advent of the bundled payment system combined with the current medical utilization climate has placed considerable pressure on surgeons to produce excellent results with early functional recovery and short hospital stays. The US obesity epidemic has transcended into the arthroplasty patient population and surgeons must assess whether obesity is a risk factor for poor outcomes in THA and determine how it should be managed. We performed a recent literature review to determine how obesity impacts outcomes in total hip arthroplasty and what must be done to improve outcomes in the obese arthroplasty patient. Our goal is to answer 3 questions: does obesity increase the complication rate in THA, if obesity matters how obese is too obese, and what must be done to improve outcomes in the obese patient? Ultimately, obesity has been shown to correlate with increased post-operative complications in THA. The arthroplasty surgeon must optimise the obese patient prior to surgery by identifying associated comorbidities and consider malnutrition screening with counseling. Notice should be taken of the degree of obesity as patients with BMI > 40 have demonstrated much higher complication rates. Strong consideration should be given to avoiding direct anterior approach in the obese patient. Healthy weight loss must be encouraged with appropriate patient counseling and treatment in order to achieve success with THA in obese patients.
Many factors contribute to the occurrence of edge-loading conditions in hip replacement; soft tissue tension, surgical position, patient biomechanical variations and type of activities, hip design, etc. The aim of this study was to determine the effect of different levels of rotational and translational surgical positioning of hip replacement bearings on the occurrence and severity of edge-loading and the resultant wear rates. The Leeds II Hip-Joint Simulator and 36mm diameter alumina matrix composite ceramic bearings (BIOLOX delta, DePuy Synthes, UK) were used in this study. Different levels of mismatch between the reconstructed rotational centres of the head and the cup were considered (2, 3 and 4mm) in the medial-lateral axis. Two cup inclination angles were investigated; an equivalent to 45 and 65 degrees in-vivo, thus six conditions (n=6 for each condition) were studied in total with three million cycles completed for each condition. The wear of the ceramic-on-ceramic bearings were determined using a microbalance (Mettler Toledo, XP205, UK) and the dynamic microseparation displacement was measured using a Liner Variable Differential Transformer.Background
Method
The femur begins to bow anteriorly at the 200 mm level, but may bow earlier in smaller people. If the stem to be used is less than 200 mm, a straight stem can be used. If the stem is longer than 200 mm, it will perforate the anterior femoral cortex. I know this because I did this on a few occasions more than 20 years ago. To use a long straight stem, there are two techniques. One can either do a diaphyseal osteotomy or one can do a Wagner split (extended trochanteric osteotomy). Both of these will put the knee in some degree of hyperextension, probably insignificant in the elderly, but it may be of significance in the young. In very young people, therefore, it may be preferable to use a bowed stem to avoid this degree of recurvatum. There are two different concepts of loading. Diaphyseal osteotomy implies a proximal loading has been sought. The Wagner split ignores the proximal femur and seeks conical fixation in the diaphysis. There will be very little bone-bone contact between what remains of the attached femur and the detached anterior cortex so that it is important to ensure that the blood supply to the anterior cortex remains intact, preferably by using Wagner's technique, using a quarter-inch osteotome inserted through the vastus to crack the medial cortex. Current modularity is of two types. Distal modularity was attempted many years ago and was never successful. Proximal modularity, as for example, the S-ROM stem, implies various sizes of sleeves fit onto the stem to get a proximal canal fill. In mid-stem modularity, the distal stem wedges into the cone. It has to be driven into where it jams and this can be somewhat unpredictable. For this reason, the solid Wagner stem has been replaced by the mid-stem modular. Once the distal femur is solidly embedded, the proximal body is then selected for height and version. The proximal body is unsupported in the mid-stem modular and initially, few fractures were noted at the taper junction. Cold rolling, shot peening and taper strengthening seem to have solved these problems. There are a variety of types of osteotomy, which can be used for different deformities. With a mid-stem modular system, generally, all that needs to be done is a Wagner-type split and fixation is sought in the mid-diaphysis by conical reaming. No matter what stem is used, distal stability is necessary. This is achieved by flutes, which engage the endosteal cortex. The flutes alone must have sufficient rotational stability to overcome the service loads on the hip of 22 Nm. I divide revision into three categories. In type one, the isthmus is intact, i.e. the bone below the lesser trochanter so that a primary stem can be used. In type two, the isthmus is damaged, i.e. the bone below the lesser trochanter, so a long revision stem is required. In a type three, there is more than 70 mm of missing proximal femur. The Wagner stem may be able to handle this on its own, but most other stems are better supported with a structural allograft cemented to the stem. The reported long term results of mid-stem modular revision implants are good as in most, over 90% survivorship. The introduction of modularity appears to have overcome initial disadvantage of the Wagner stem, i.e. its unpredictability in terms of leg length.
Trabecular titanium implants are 3D printed with a high-friction ingrowth surface that is continuous with the rest of the acetabular shell. The ability to “face-change” following optimum seating of the component allows unprecedented levels of versatility in acetabular orientation. Bolt-on augments enable rapid trialling and definitive insertion of a monobloc construct. The use of these implants has rapidly increased in the National Joint Registry over the last three years with little published outcome data. We present one of the largest studies using this material. This study assesses the early stability, ingrowth and clinical outcome of revision acetabular reconstruction with trabecular titanium.Introduction
Objectives
Stable fixation of cementless tibial trays remains a challenge due bone density variability within the proximal tibia and the spectrum of loads imposed by different activities. This study presents a novel approach to measuring the interface motion of cementless tibial components during functional loading and tests whether interface motion of cementless tibial trays varies around the implant periphery. We developed a method to measure relative displacement of a tibial tray relative to the underlying bone using 3D digital image correlation (DIC) and multi-camera stereo photogrammetry. A clinically successful design of cementless total knee prosthesis (Zimmer Inc, Warsaw, IN) was implanted in 6 fresh cadaveric knees. A black-on-white stochastic pattern was applied to the outer surface of the tibia and the cementless prosthesis. High resolution digital images were prepared of the interface region and divided into 25 × 25 pixel regions of interest (ROI). Stereo images of the same ROI were generated using two cameras angled at 60 degrees using image correlation techniques. All specimens were mounted in a custom-built functional activity simulator and loaded with the forces and moments recorded during three common functional activities (standing from a seated position, walking, and stair descent), as reported in the Orthoload database, scaled by 50% for application to cadaveric bone. Prior to functional testing, each implant-tibia construct was preconditioned with 500 cycles of flexion from 5–100 degrees under a vertical tibial load of 1050 N at a frequency of 0.2 Hz. During loading, image data was acquired simultaneously (±20 μs) from the entire circumference of the tibial interface forming 4 stereo images using 8 cameras spaced at 90 degree intervals (Allied Vision Technologies, Exton, PA) using custom image acquisition software (Mathworks, Natick, MA) (Figure 1). The multiple stereo images were registered using the surface topography of each specimen as measured by laser scanning (FARO Inc., Montreal) (Figure 2). During post-processing, the circumferential tray/tibia interface was divided into 10 zones for subsequent analysis (Figure 3). Interface displacements were measured on a point-to-point basis at approximately 700 sites on each specimen using commercial DIC software (Dantec Dynamics, Skovlunde, Denmark) (Figure 4).INTRODUCTION
METHODS
Clinically many factors such as variations in surgical positioning, and patients' anatomy and biomechanics can affect the occurrence and severity of edge loading which may have detrimental effect on the wear and durability of the implant. Assessing wear of hundreds of combinations of conditions would be impractical, so a preclinical testing approach was followed where the occurrence and severity of edge loading can be determined using short biomechanical tests. Then, selected conditions can be chosen under which the wear can be determined. If a wear correlation with the magnitude of dynamic separation or the severity of edge loading can be shown, then an informed decision can be made based upon the biomechanical results to only select important variables under which the tribological performance of the implant can be assessed. The aim of this study was to determine the relationship between the wear of ceramic-on-ceramic bearings and the (1) magnitude of dynamic separation, (2) the maximum force reached during edge loading and (3) the severity of edge loading resulting from component translational mismatch between the head and cup centres. The Leeds II hip joint simulator with a standard walking cycle and 36mm diameter ceramic-on-ceramic bearings (BIOLOX® delta, DePuy Synthes Joint Reconstruction, Leeds, UK.) were used. The study was in two parts. Part one: a biomechanical study where the dynamic separation, the maximum load during edge loading, and the duration of edge loading alongside the magnitude of forces under edge loading (severity of edge loading) were assessed. Part two; a wear study where the wear rates of the bearing surfaces were assessed under a series of input conditions. These input testing conditions included inclining the acetabular cups at 45° and 65° cup inclination angle (in-vivo equivalent), with 2, 3, and 4mm medial-lateral component mismatch between the centres of the head and the cup. This equated to six conditions being assessed, each with three repeats for the biomechanical test, and six repeats completed for the wear study. The severity of edge loading was assessed as described in Equation 1. Severity of Edge Loading = ∫tt0 F(x) dx + ∫tt0 F(y) dy … Equation 1, where F(x) is the axial load, F(y) is the medial-lateral load and t-t0 is the duration of edge loading. The wear of the ceramic bearings were determined using gravimetric analysis (XP205, Mettler Toledo, UK).Introduction and Aims
Methods
Humeral radiolucent lines after anatomic TSA (aTSA) have been well described; however, little clinical consequences have been attributed to them. The recent emergence of shorter humeral stems has demonstrated higher incidences of humeral radiolucencies than has been reported historically with standard length components. This large scale database analysis quantifies and compares the clinical outcomes of aTSAs with and without radiolucent humeral lines using one specific prosthesis to determine their impact on clinical outcomes. This is a multicenter, retrospective, case controlled radiographic and clinical review. Preoperative and postoperative data was analyzed from 671 aTSA patients with a minimum of 2 years followup. 538 of these 671 aTSA patients had full radiographic followup (80.2%) and were included in this study; these patients had an average followup of 45.3 months). 459 patients had noncemented humeral stems; whereas, 79 patients had cemented humeral stems. Radiographs were reviewed at latest follow up for humeral radiolucent lines based on the technique described by Gruen et al. Patients were evaluated and scored pre-operatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI scoring metrics; ROM was also recorded. A Student's two-tailed, unpaired t-test was used to identify differences in pre-operative, post-operative, and improvement in results, where p<0.05 denoted a significant difference.Introduction
Methodology
Hip resurfacing arthroplasty (HRA) is currently regaining positive attention as a treatment of osteoarthritis in young, active individuals[1]. The procedure is complex and has low tolerance for implant malpositioning [2]. ‘Precision tools', such as imageless navigation and patient specific instruments, have been developed to assist with implant positioning but have not been shown to be fully reliable [3]. The aim of this study is to present and validate the first step of novel quality control tool to verify implant position intra-operatively. We propose that, before reaming of the femoral head, a handheld structured light 3D scanner can be used to assess the orientation and insertion point of femoral guide wire. Guide wires were placed into the heads of 29 solid foam synthetic femora. A specially designed marker (two orthogonal parallelepipeds attached to a shaft) was inserted into the guide wire holes. Each bone (head, neck and marker) was 3D scanned twice (fig 1). The insertion point and guide wire neck angle were calculated from the marker's parameters. Reference data was acquired with an optical tracking system. The measurements calculated with the 3D scans were compared to the reference ones to evaluate the precision. The comparison of the test retest measurements done with the new method are used to evaluate intra-rater variability.Introduction
Methods
Cementless tibial trays commonly fail through failure of fixation due to excessive interface motion. However, the specific combination of axial and shear forces precipitating implant failure is unknown. This has led to generic loading profiles approximating walking to perform pre-clinical assessment of new designs, even though telemetric data demonstrates that much larger forces and moments are generated during other functional activities. This study was undertaken to test the hypotheses: (i) interface motion of cementless tibial trays varies as a function of specific activities, and (ii) the response of the cementless tibial interface to walking loading is not representative of other functional activities. Six fresh-frozen cadaveric tibias were tested using a custom designed functional activity simulator after implantation of a posterior stabilized total knee replacement (NexGen LPS, Zimmer, Warsaw IN). Activity scenarios were selected using force (Fx, Fy, Fz) and moment (Mx, My, Mz) data from patients with instrumented tibial trays (E-tibia) published by Bergmann et al. A pattern of black and white spray paint was applied to the surface of the specimen including the tibial tray and bone. Each specimen was preconditioned through application of a vertical load of 1050N for 500 cycles of flexion-extension from 5–100°. Following preconditioning, each tibia was loaded using e-tibia values of forces and moments for walking, stair-descent, and sit-to-stand activities. The differential motion of the tibial tray and the adjacent bony surface was monitored using digital image correlation (DIC) (resolution: 1–2 microns in plane; 3–4 microns out-of-plane). Four pairs of stereo-images of the tray and tibial bone were prepared at sites around the circumference of the construct in both the loaded and unloaded conditions: (i) before and after pre-conditioning and (ii) before and after the 6 functional loading profiles. The images were processed to provide circumferential measurements of interface motion during loading. Differences in micromotion and migration were evaluated statistically using step-wise multivariate regression.INTRODUCTION
MATERIALS and METHODS
There are many variables that can affect the occurrence and severity of edge loading in hip replacement. A translational mismatch between the centres of rotation of the head and cup may lead to dynamic separation, causing edge loading and increased wear. Combining a steep inclination angle with such translational mismatch in the medial-lateral axis caused a larger magnitude of separation and increased severity of edge loading. Previous studies have shown variation in the hip Swing Phase Load (SPL) during gait between different patients. The aim of this study was to apply a translational mismatch and determine the effect of varying the SPL on the occurrence and severity of edge loading under different cup inclination angles in a hip joint simulator. The Leeds II hip joint simulator with a standard gait cycle and 36mm diameter ceramic-on-ceramic bearings (BIOLOX® delta) were used in this study. The study was in two stages; [1] a biomechanical study where the magnitude of dynamic separation, the duration of edge loading and the magnitude of force under edge loading (severity) were assessed under variations in component positioning and SPLs. [2] A wear study to assess edge loading with selected input conditions. For the biomechanical study, a combination of four mismatches, three cup inclination angles, and eight SPLs (Table 1) were investigated. For the wear study, three SPL conditions were selected with one cup angle and one mismatch (Table 1). Three million cycles were completed under each condition. Mean wear rates and 95% confidence limits were determined and statistical analysis (one way ANOVA) completed (significance taken at p<0.05). Table 1: Study matrixIntroduction and Aims
Methods
Mal-positioning of the acetabular component in total hip replacement (THR) could lead to edge loading, accelerated component wear, impingement and dislocation [1,2]. In order to achieve a successful position for the acetabular component, the assessment of the acetabular orientation with reference to different coordinate systems is important [3]. The aims of the present study were to establish a pelvic coordinate system and a global body coordinate system, and to assess the acetabular orientations of natural hips with reference to the two coordinate systems. Three-dimensional (3D) computed tomographic (CT) images of 56 subjects (28 males and 28 females) lying supine were obtained from a public image archive (Cancer Image Archive, website: INTRODUCTION
METHODS
Periprosthetic infections are leading causes of revision surgery resulting in significant increased patient comorbidities and costs. Considerable research has targeted development of biomaterials that may eliminate implant-related infections.1 This Several surface treated silicon nitride (Si3N4, Introduction
Materials and Methods
The performance of total hip replacement (THR) devices can be affected by the quality of the tissues surrounding the joint or the mismatch of the component centres during hip replacement surgery. Experimental studies have shown that these factors can cause the separation of the two components during walking cycle (dynamic separation) and the contact of the femoral head with the rim of the acetabular liner (edge loading), which can lead to increased wear and shortened implant lifespan1. There is a need for flexible pre-clinical testing tools which allow THR devices to be assessed under these adverse conditions. In this work, a novel dynamic finite element model was developed that is able to generate dynamic separation as it occurs during the gait cycle. In addition, the ability to interrogate contact mechanics and material strain under separation conditions provides a unique means of assessing the severity of edge loading. This study demonstrates these model capabilities for a range of simulated surgical translational mismatch values, for ceramic-on-polyethylene implants. The components of the THR were aligned and constrained as illustrated in Figure 1. CAD models of commercially available implant geometries were used (DePuy Synthes, Leeds, UK) modified for model simplicity by removing anti-rotation features. The polyethylene cup liner was given elastic-plastic behaviour. An axial load following the Paul cycle pattern (5 repetitive cycles) with maximum of 3KN and swing phase load of 0.3KN, was applied through the cup holder. The effect of translational mismatch was implemented by using a spring element connected to the cup unit on the lateral side. The spring was compressed by a fixed amount to replicate a degree of medial-lateral mismatch of the components. The instantaneous resultant force vector dictated the dynamic sliding behaviour of the cup against the head. In this study, translational medial-lateral mismatch values of 1, 2, 3 and 4mm were used and the medial-lateral dynamic separation, contact pressure maps and plastic strain were recorded.Introduction
Methodology
As computer navigated surgery continues to progress to the forefront of orthopedic care, the application of a navigated total shoulder arthroplasty has yet to appear. However, the accuracy of these systems is debated, as well as the dilemma of placing an accurate tool in an inaccurate hand. Often times a system's accuracy is claimed or validated based on postoperative imaging, but the true positioning is difficult to verify. In this study, a navigation system was used to preoperatively plan, guide, and implant surrogate shoulder glenoid implants and fiducials in nine cadaveric shoulders. A novel method to validate the position of these implants and accuracy of the system was performed using pre and post operative high resolution CT scans, in conjunction with barium sulfate impregnated PEEK surrogate implants. Nine cadaveric shoulders were CT scanned with .5mm slice thickness, and the digital models were incorporated into a preoperative planning software. Five orthopedic shoulder specialists used this software to virtually place aTSA and rTSA glenoid components in two cadavers each (one cadaver was omitted due to incomplete implantation), positioning the components as they best deemed fit. Using a navigation system, each surgeon registered the native cadaveric bone to each respective CT. Each surgeon then used the navigation system to guide him or her through the total shoulder replacement, and implant the barium sulfate impregnated PEEK surrogate implants. Four cylindrical PEEK fiducials were also implanted in each scapula to help triangulate the position of the surrogate implants. Previous efforts were attempted with stainless steel alloy fiducials, but position and image accuracy were limited by CT artifact. BaSO4 PEEK provided the highest resolution on a postoperative CT with as little artifact as possible. All PEEK fiducials and surrogate implants were registered by probing points and planes with the navigation system to capture the digital position. A high resolution post operative CT scan of each specimen was obtained, and variance between the executed surgical plan and PEEK fiducials was calculated.INTRODUCTION
METHODS
Because of the low cost and easy access, surgical video has become a popular method of acquiring surgical skills outside operating rooms without disrupting normal surgical flow. However, currently existing video systems all use a single point of view (POV). Some complex orthopedic procedures, such as joint replacement, require a level of accuracy in several dimensions. So single and fixed POV video may not be enough to provide all the necessary information for educational and training purposes. The aim of our project was to develop a novel multiple POV video system and evaluate its efficacy as an aid for learning joint replacement procedure compared with traditional method. Based on the videos of a hip resurfacing procedure performed by an expert orthopedic surgeon captured by 8 cameras fixed all around the operating table, we developed a novel multiple POV video system which enables users to autonomously switch between optimal viewpoints (Figure 1). 30 student doctors (undergraduate years 3–5 and naive to hip resurfacing procedure) were recruited and randomly allocated to 2 groups: experiment group and control group, and were assigned to learn the procedure using multiple or single POV video systems respectively. Before learning they were first asked to complete a multiple choicetest designed using a modified Delphi technique with the advice and feedback sought from 4 experienced orthopedic surgeons to test the participants' baseline knowledge of hip resurfacing procedure. After video learning, they were asked to answer the test again to verify their gained information and comprehension of the procedure, followed by a 5-point Likert-scale questionnaire to demonstrate their self-perception of confidence and satisfaction with the learning experience. The scores in the 2 tests and in the Likert-scale questionnaire were compared between 2 groups using Independent-Samples t-test (for normally distributed data) or Mann-Whitney U test (for non-normally distributed data). Statistical significance was set as p<0.05.Introduction
Materials and Methods
Recent advances in materials and manufacturing processes for arthroplasty have allowed fabrication of intricate implant surfaces to facilitate bony attachment. However, refinement and evaluation of these new design strategies is hindered by the cost and complications of animal studies, particularly during early iterations in development process. To address this problem, we have constructed and validated an Cancellous cylindrical bone cores were harvested from bovine metatarsals and divided into five groups under different conditions. After incubation for 4 & 7 weeks, the viability of each bone sample was evaluated using Live-Dead assay and microscopic anatomy of cells were determined using histology stain H&E. Matrix deposits on the scaffolds were examined with scanning electron microscopy (SEM) while its chemical composition was measured using energy-dispersive x–ray spectroscopy (EDX).Background
Methods
As the population continues to grow and age, the incidence of revision total knee replacement (RTKR) is expected to rise significantly. Modularity within revision total knee systems is common, and recognition of modular junctions as an important source adverse local tissue reaction (ALTR) has not yet been fully described in the literature. In both hips and knees, ALTR may be caused by wear debris from articulating surfaces, stress shielding, and other classic areas of focus, but now attention is shifting towards the role of corrosion products from modular junctions. In severe cases, junctions can become welded together creating significant hurdles in revisions and potentially altered biomechanics in vivo. In view of these issues, the present study was undertaken: (i) to examine the level of damage observed in modular junctions of total knee prostheses obtained at revision, (ii) to correlate the severity of surface damage to the design and composition of the mating components, and (iii) to associate patient demographics and comorbidities with the spectrum of corrosion and fretting seen in retrieved implants. 117 TKR components from 76 patients were examined after retrieval from revision procedures performed at a single institution. Patient demographics and clinical data were compiled. The retrievals consisted of 57 femoral components and 60 tibial components from a diverse range of manufacturers. The implants were disassembled manually, or in a mechanical testing machine if cold welded, and separated into groups based on mating material type. Modular junctions were then examined using stereomicroscopy (Wild) at magnifications of X6 to X31. Upon inspection, damage on the male component was graded using modified Goldberg scales for corrosion and fretting (Table 1). Factors associated with trunnions having damage scores of 3 or higher were evaluated using standard statistical procedures to determine the susceptibility for corrosion of each junction type and location.Introduction
Methods
Corrosion products from modular taper junctions of hip prostheses have been implicated in adverse local tissue reactions after THR. Numerous factors have been proposed as the root causes of this phenomenon, including implant design and materials, manufacturing variables, intraoperative assembly, and patient lifestyle. As significant taper damage only occurs in a few percent of cases of THR, we have addressed this complication using a “forensic” examination of retrieval specimens to gain insight into the factors initiating the cascade leading to irreversible damage of the modular interface. In this study we report the categorization of over 380 retrievals into groups having shared damage patterns, metallic composition, and interface surface geometries to isolate the genesis of mechanically-assisted corrosion and its relation to intraoperative assembly, manufacturing, and postoperative loading. A total of 384 femoral components were examined after retrieval at revision THR. The implants were produced by a diverse range of manufacturers, 271 in CoCr, and 113 in TiAlV, with both smooth (253) and machined (131) tapers. Initially, the implants were sorted into groups based on composition and taper roughness. Each trunnion was then cleaned to remove organic deposits and examined by stereomicroscopy at X6-X31. After an initial pilot study, we developed a classification system consisting of 8 basic patterns of damage (Table 1). We then classified all 384 trunnions according to this 8-group system. The prevalence of each pattern was calculated on the basis of both composition and surface texture of the trunnion.Introduction
Methods
Prosthetic joint infection (PJI) is an uncommon but serious complication of hip and knee replacement. We investigated the rates of revision surgery for the treatment of PJI following primary and revision hip and knee replacement, explored time trends, and estimated the overall surgical burden created by PJI. We analysed the National Joint Registry for England and Wales for revision hip and knee replacements performed for a diagnosis of PJI and their index procedures from 2003–2014. The index hip replacements consisted of 623,253 primary and 63,222 aseptic revision hip replacements with 7,642 revisions subsequently performed for PJI; for knee replacements the figures were 679,010 primary and 33,920 aseptic revision knee replacements with 8,031 revisions subsequently performed for PJI. Cumulative incidence functions, prevalence rates and the burden of PJI in terms of total procedures performed as a result of PJI were calculated. Revision rates for PJI equated to 43 out of every 10,000 primary hip replacements (2,705/623,253), i.e. 0.43%(95%CI 0.42–0.45), subsequently being revised due to PJI. Around 158 out of every 10,000 aseptic revision hip replacements performed were subsequently revised for PJI (997/63,222), i.e. 1.58%(1.48–1.67). For knees, the respective rates were 0.54%(0.52–0.56) for primary replacements, i.e. 54 out of every 10,000 primary replacements performed (3,659/679,010) and 2.11%(1.96–2.23) for aseptic revision replacements, i.e. 211 out of every 10,000 aseptic revision replacements performed (717/33,920). Between 2005 and 2013, the risk of revision for PJI in the 3 months following primary hip replacement rose by 2.29 fold (1.28–4.08) and after aseptic revision by 3.00 fold (1.06–8.51); for knees, it rose by 2.46 fold (1.15–5.25) after primary replacement and 7.47 fold (1.00–56.12) after aseptic revision. The rates of revision for PJI performed at any time beyond 3 months from the index surgery remained stable or decreased over time. From a patient perspective, after accounting for the competing risk of revision for an aseptic indication and death, the 10-year cumulative incidence of revision hip replacement for PJI was 0.62%(95%CI 0.59–0.65) following primary and 2.25%(2.08–2.43) following aseptic revision; for knees, the figures were 0.75%(0.72–0.78) following primary replacement and 3.13%(2.81–3.49) following aseptic revision. At a health service level, the absolute number of procedures performed as a consequence of hip PJI increased from 387 in 2005 to 1,013 in 2014, i.e. a relative increase of 2.6 fold. While 70% of those revisions were two-stage, the use of single stage revision increased from 17.6% in 2005 to 38.5% in 2014. For knees, the burden of PJI increased by 2.8 fold between 2005 and 2014. Overall, 74% of revisions were two-stage with an increase in use of single stage from 10.0% in 2005 to 29.0% in 2014. Although the risk of revision due to PJI following hip or knee replacement is low, it is rising. Given the burden and costs associated with performing revision joint replacement for prosthetic joint infection and the predicted increased incidence of both primary and revision hip replacement, this has substantial implications for service delivery.
Obtaining primary wound healing in total joint arthroplasty (TJA) is essential to a good result. Wound healing disturbances (WHD) can occur and the consequences can be devastating to the patient and to the surgeon. Determination of the host healing capacity can be useful in predicting complications. Cierney and Mader classified patients as Type A: no healing compromises and Type B: systemic or local healing compromise factors present. Local factors include traumatic arthritis with multiple previous incisions, extensive scarring, lymphodema, poor vascular perfusion, and excessive local adipose deposition. Systemic compromising factors include diabetes, rheumatic diseases, renal or liver disease, immunocompromise, steroids, smoking, and poor nutrition. Low serum albumin, total lymphocyte count, and low transferrin increase WHD. In high risk situations the surgeon should encourage positive patient choices such as smoking cessation and nutritional supplementation to modify healing responses. Use of tourniquet in obese patients also increases WHD. Careful planning of incisions, particularly in patients with scarring or multiple previous operations, is productive. Around the knee the vascular viability is better in the medial flap. Thusly, use the most lateral previous incision, do minimal undermining, and handle tissue meticulously. We do all potentially complicated TKA's without tourniquet to enhance blood flow and tissue viability. The use of perioperative anticoagulation will increase wound problems. If wound drainage or healing problems do occur, immediate action is required. Deep sepsis can be ruled out with a joint aspiration and cell count (less than 2500), differential (less than 60% polys), and negative culture and sensitivity. All hematomas should be evacuated and necrosis or dehiscence should be managed by debridement to obtain a live wound.
The major benefit of TKA with tourniquet is operating in a bloodless field. A possible secondary benefit is a better cement-bone interface for fixation. The disadvantages of tourniquet use for TKA include multiple risk factors both local and systemic: Nerve damage, Altered hemodynamics with limb exsanguinations (15–20% increase in circulatory volume) and reactive hyperemia with tourniquet release (10% increase in limb size increasing soft tissue tension and secondary pain), Delay in recovery of muscle function, Increased risk of DVT with direct trauma to vessel walls and increased levels of thrombin-antithrombin complexes, A 5.3x greater risk for large venous emboli propagation and transesophageal echogenic particles, Vascular injury with higher risk in atherosclerotic, calcified arteries, Increase in wound healing disturbances, Obese patients TKA with tourniquet show impaired endothelial function and more DVTs. Our initial experience with TKA without tourniquet was in high risk patients with previous DVT or PE, multiple scarring, or compromised cardiovascular status. We have used this method on all patients for the last 14 years. The protocol includes regional anesthesia, incision and approach made with 90-degree knee flexion, meticulous hemostasis, jet lavage and filtered carbon dioxide delivered to dry and prepare bone beds for cementation, application of topical tranexamic acid and routine closure. We have encountered no differences in blood loss or transfusion rates, cement penetration/ fixation, less postoperative pain, faster straight leg raise and knee flexion gains, and fewer wound healing disturbances. We recommend TKA sans tourniquet. Let it bleed!
In the USA, 34.9% of adults are currently obese (BMI > 30). Growth in total knee arthroplasty (TKA) is outpacing growth in total hip arthroplasty (THA) largely due to a differential utilization of TKA in overweight patients in the USA. In a recent study, 54.5% of patients reporting to arthroplasty clinics in the USA were obese. From 2006–2010, 61.2% of primary unilateral TKA patients in the USA ACS-NSQIP database were obese. Arthroplasty surgeons are directly affected by the obesity epidemic and need to understand how to safely offer a range of peri-operative care for these patients in order to insure good clinical outcomes. Pre-operative care for the obese patient involves nutritional counseling, weight loss methods, consideration for bariatric surgery, physical therapy, metabolic workup, and diagnosis and management of frequent comorbid conditions (OSA, DM2, HTN, HLD). Obese patients must also be counseled on their increased risk of complications following TKA. In the operating room, several steps can be taken to insure success when performing TKA on obese patients. We recommend performing TKA without the use of a tourniquet in order to prevent fat necrosis and increased pain. The incision is made in 90 degrees of knee flexion, atypically midline proximally and curved distally to the midpoint between the tubercle and the medial edge of the tibia. Care is used to minimise the creation of dead space, and the approach to the knee is an extensile medial parapatellar incision. Closure is in multiple layers. The use of negative pressure dressing following surgery can minimise the early wound drainage that is frequently seen after TKA in obese patients. Post-operative care of the obese patient following TKA involves several unique considerations. Chronic pain and obesity are frequent comorbid conditions and post-operative pain control regimens need to be tailored. Although the physical therapy regimen does not differ in obese patients, obese patients are more likely to be discharged to a rehabilitation facility. Obese patients have a higher rate of all complications compared to healthy weight. All infection and deep infection increased in obese patients in large meta-analysis. Patients with BMI > 35 are 6.7 times more likely to develop infection after TKA. Patients with BMI > 40 have a 3.35 times higher rate of revision for deep infection than those with BMI < 35. The odds ratio for major complications increases dramatically beyond BMI > 45. Although there are a few studies that have demonstrated worse clinical outcome in obese patients following TKA, most studies show no difference in clinical outcomes at short- or long-term follow-up. The arthroplasty surgeon must optimise the obese patient prior to surgery, use intra-operative techniques to maximise success, and anticipate potential problems in the post-operative course in order to achieve success with TKA in obese patients.
Persistent post-surgical pain (PPSP) remains a problem after knee replacement with some studies reporting up to 20% incidence. Pain is usually felt by those who do not operate to be a monolithic entity. All orthopaedic surgeons know that this is not the case. At its most basic level, pain can be divided into two categories, mechanical and non-mechanical. Mechanical pain is like the pain of a fresh fracture. If the patient does not move, the pain is less. This type of pain is relieved by opiates. Mechanical pain is seen following knee replacement, but is becoming less frequent. It is caused by a combination of malrotations and maltranslations, often minor, which on their own would not produce problems. The combination of them, however, may produce a knee in which there is overload of the extensor mechanism or of the medial stabilizing structures. If these minor mechanical problems can be identified, then corrective surgery will help. Non-mechanical pain is present on a constant basis. It is not significantly worsened by activities. Opiates may make the patient feel better, but they do not change the essential nature of the pain. Non-mechanical pain falls into three broad groups, infection, neuropathic and perceived pain. Infection pain is usually relieved by opiates. Since some of this pain is probably due to pressure, its inclusion in the non-mechanical pain group is questionable, but it is better left there so that the surgeon always considers it. Low grade chronic infection can be extremely difficult to diagnose. Loosening of noncemented knee components is so rare that when it is noted radiologically, infection should be very high on the list of suspicions. The name neuropathic pain suggests that we know much more about it than we do in reality. Causalgia or CRPS-type two is rare following knee replacement. CRPS-type one or reflex sympathetic dystrophy probably does exist, but it is probably over-diagnosed. The optimum treatment I have found is lumbar sympathetic blocks. Lyrica, Gabapentin and Cymbalta may also help. Perceived pain is the largest group. It does not matter what you tell the patient, some believe a new knee should be like a new car, i.e. you step into it and drive away. The fact that they have to work to make it work is horrifying. Perceived pain is widespread. The classic treatise, Dr. Ian McNabb's book “Backache”, should be studied by all who wish to understand pain complaints. Any experienced knee surgeon will have his list of red flags or caveats. I will list only a few. If the patient comes in with a form asking for a disability pension on the first visit. If the patient's mother answers the questions. If the patient comes in taking massive doses of opiates. If the patient is referred to you by a surgeon who does more knee replacements than you do. There are other issues such as good old fibromyalgia, which appears to have gone the way of the dodo. It has been replaced by something equally silly called central sensitization. The theory of central sensitization is that if one has pain somewhere or other for three months or six months or whatever, there are going to be changes in the brain and spinal cord. It then does not matter what happens to the original pain, i.e. whether or not it goes away, the pain will persist because of the changes in the brain, hence, the title of the pain in the brain syndrome. If this theory was correct, we might as well all go home because we have all been wasting our time for the last 30 years because none of our patients would get any better. After all, all of our patients have had pain for a lot longer than three months, many of them have been involved in trauma and sometimes, compensation is at issue. The pain in the brain theory, therefore, sounds about as realistic as the flat earth society or the treatment of Galileo.
Functional restoration of patella kinematics is an essential component of TKA, whether the patella is replaced or not. This goal is accomplished by a multifactorial approach: establish proper component position and alignment, especially rotation, avoid IR of the femoral and ER of the tibial components, maintain correct joint line position, achieve symmetrical soft tissue balance Most modern TKA designs have an anatomic trochlear groove shape to enable midline tracking. Patella implants are better designed as well with three equilateral lugs for fixation and either dome or anatomic shape. The apex of the patella component should be aligned with the apex of the patella raphe which is more medial than lateral. This method leaves an island of exposed lateral patella facet which is managed with the “lateral slat technique” to be described. It is essentially an intraosseous lateral release. The early mobilization of modern TKA patients demands watertight closure to prevent soft tissue attenuation and late tracking issues. When confronted with a patient with a laterally dislocated patella, implementation of the “lateral slat technique” should be done at the approach to obtain midline tracking. Such patients require a median parapatellar (MPP) approach and may need distal-lateral vastus medialis advancement (Insall procedure). Adherence to the principles iterated herein will produce a happy patient with good patello-femoral kinematics and function.
Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of surgical approach on gait kinetics and kinematics. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis. Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardised implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance. All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group. Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question.
Adductor canal blocks offer an alternative to femoral nerve block for postoperative pain relief in knee arthroplasty. They may reduce the risk of quadriceps weakness, allowing earlier mobilisation of patients postoperatively. However, little is known about the effect of a tourniquet on the distribution of local anaesthetic in the limb. Ultrasound-guided adductor canal blocks were performed on both thighs of five human cadavers. Left and right thighs of each cadaver were randomised to tourniquet or no tourniquet for one hour. Iohexol radio-opaque contrast (Omnipaque 350) was substituted for the local anaesthetic for X-Ray imaging. All limbs underwent periodic flexion and extension during this hour to simulate positioning during surgery. The cadavers were refrozen. Fiducial markers were inserted into the frozen tissue. X-rays were obtained in 4 planes (AP, lateral 45° oblique/medial oblique, lateral). University Research Ethics Approval was obtained and cadavers were all pre-consented for research, imaging and photography according to the Anatomy Act (1984). Analysis of radiographs showed contrast distribution in all thighs to be predominantly on the medial aspect of the thighs. The contrast margins were entire and well circumscribed, strongly suggesting it was largely contained within the aponeurosis of the adductor canal. Tourniquets appeared to push the contrast into a narrower and more distal spread along the length of the thigh compared to a more diffuse spread for those without. Proximal spread towards the femoral triangle was reduced in limbs without tourniquets. The results suggest that contrast material may remain within the adductor canal structures during adductor canal blocks. Tourniquets may cause greater distribution of contrast proximally and distally in the thigh, but this does not appear to be clinically significant. Further studies might include radio-stereo photometric analysis using the fiducial markers in the limbs and in vivo studies to show the effect of haemodynamics on distribution.
The aim of this to study was to compare the previously unreported
long-term survival outcome of the Oxford medial unicompartmental
knee arthroplasty (UKA) performed by trainee surgeons and consultants. We therefore identified a previously unreported cohort of 1084
knees in 947 patients who had a UKA inserted for anteromedial knee
arthritis by consultants and surgeons in training, at a tertiary
arthroplasty centre and performed survival analysis on the group
with revision as the endpoint.Aims
Patients and Methods
To compare the gait of unicompartmental knee arthroplasty (UKA)
and total knee arthroplasty (TKA) patients with healthy controls,
using a machine-learning approach. 145 participants (121 healthy controls, 12 patients with cruciate-retaining
TKA, and 12 with mobile-bearing medial UKA) were recruited. The
TKA and UKA patients were a minimum of 12 months post-operative,
and matched for pattern and severity of arthrosis, age, and body
mass index. Participants walked on an instrumented treadmill until their
maximum walking speed was reached. Temporospatial gait parameters,
and vertical ground reaction force data, were captured at each speed.
Oxford knee scores (OKS) were also collected. An ensemble of trees
algorithm was used to analyse the data: 27 gait variables were used
to train classification trees for each speed, with a binary output
prediction of whether these variables were derived from a UKA or
TKA patient. Healthy control gait data was then tested by the decision
trees at each speed and a final classification (UKA or TKA) reached
for each subject in a majority voting manner over all gait cycles
and speeds. Top walking speed was also recorded.Aims
Patients and Methods
Acute Achilles tendon (AT) rupture management remains debatable but non-operative functional regimes are beginning to dominate current treatment algorithms. The aim of this study was to identify predictors of functional outcome in patients with AT ruptures treated non-operatively with an immediate weight bearing functional regime in an orthosis. Analysis of prospectively gathered data from a local database of all patients treated non-operativelyat our institution with anAT rupture was performed. Inclusion criteria required a completed Achilles Tendon Rupture Score (ATRS) at a minimum of 8 months post rupture. The ATRS score was correlated against age, gender, time following rupture, duration of treatment in a functional orthoses (8- and 11-week regimes) and complications. 236 patients of average age 49.5 years were included. The mean ATRS on completion of rehabilitation was 74 points. The mean ATRS was significantly lower in the 37 females as compared to the 199 males, 65.8 vs 75.6 (p = 0.013). Age inversely affected ATRS with a Pearsons correlation of −0.2. There was no significant difference in the ATRS score when comparing the two different treatment regime durations. There were 12 episodes of VTE and 4 episodes of re-rupture. The ATRS does not change significantly after 8 months of rupture. Patients with AT ruptures treated non-operatively with a functional rehabilitation regime demonstrate good function with low re-rupture rates. Increasing age and female gender demonstrate inferior functional outcomes.
