Recent studies indicated that the knee has a single flexion/extension axis but debated the location of this axis. The relationship of the flexion/extension axis in the coronal plane to the mechanical axis has received little attention. The purpose of this study was to investigate the relationship of the various axes and references with respect to the mechanical axis in the coronal plane Subjects were prospectively scanned into a Virtual Bone Database (Stryker Orthopaedics, Mahwah, NJ). Database is a collection of body CT scans from subjects collected globally. Only CT Scans that met the following qualifications were accepted: ≤1 mm voxels and had slice thickness that was equal to the spacing between the slices (≤ 1.0mm). For each CT Scan, a frontal plane was created through the 2 most posterior points of the medial/lateral condyles and the most posterior point of the trochanter. Then, a transverse plane was created perpendicular to the frontal plane and bisects the 2 most distal points on the medial/lateral condyles. Finally, a saggital plane was created that was perpendicular to the frontal and transversal planes. The following axes were identified: Mechanical Axis of the Femur (MAF) (line between the center of the femoral head and the center of the knee sulcus); Transepicondylar Axis Posterior Cylindrical Axis (PCA) (line between the Medial/Lateral Condylar Circle – best fit circle to three points identified on surface). Measurements made: Angle of MAF and the Joint-Line (Femoral Joint Angle), Angle of the MAF and the Transepicondylar Axis (Femoral TE Angle), and Angle of the MAF and the Posterior Cylindrical Axis (Femoral PC angle). Angles measuring 90° were neutral or perpendicular to the MAF. Angles measured <90° were valgus and >90° were varus.INTRODUCTION
MATERIALS AND METHODS
Many studies have looked at the effects of titanium tibial baseplates compared to cobalt chrome baseplates on backside wear. However, the surface finish of the materials is usually different (polished/unpolished) [1,2]. Backside wear may be a function not only of tray material but also of the locking mechanism. The purpose of this study was to evaluate the wear performance of conventional polyethylene inserts when mated with titanium tibial trays or cobalt chrome tibial trays that both have non-polished topside surfaces. Three titanium (Ti) trays were used along with three cobalt chrome (CoCr) trays. The Ti trays underwent Type II anodization prior to testing. All trays were Triathlon® design (Stryker Orthopaedics, Mahwah, NJ). Tibial inserts were manufactured from GUR 1020 conventional polyethylene then vacuum/flush packaged and sterilized in nitrogen (30 kGy). Appropriate sized CoCr femoral components articulated against the tibial inserts (Triathlon®, Stryker Orthopaedics, Mahwah, NJ). Surface roughness of the tibial trays was taken prior to testing using white light interferometry (Zygo Corp, Middlefield, CT). A 6-station knee simulator (MTS, Eden Prairie, MN) was used for testing. Two phases were conducted. The first phase used a normal walking profile, as dictated by ISO 14243-3 [3]. The second phase used waveforms created specifically for stair climbing kinematics. Testing was conducted at a frequency of 1 Hz for 2 million cycles for each test with a lubricant of Alpha Calf Fraction serum (Hyclone Labs, Logan, UT) diluted to 50% with a pH-balanced 20-mMole solution of deionized water and EDTA (protein level = 20 g/l) [4]. The serum solution was replaced and inserts were weighed for gravimetric wear at least every 0.5 million cycles. Standard test protocols were used for cleaning, weighing and assessing the wear loss of the tibial inserts [5]. Soak control specimens were used to correct for fluid absorption with weight loss data converted to volumetric data (by material density). Statistical analysis was performed using the Student's t-test (p<0.05).INTRODUCTION
MATERIALS AND METHODS
Computer-assisted surgery (CAS) is a tool developed to allow accurate limb and implant alignment in TKA. The strength of the technology is that it allows the surgeon to assess soft tissue balance and ligament laxity in flexion and extension. The accuracy of this ligament balancing technology depends upon an accurate determination of femoral component size. This size is established with intraoperative surface registration techniques. Customized instrumentation (CI) is a measured resection technique in which component size is established on preoperative 3D MRI reconstructions. The purpose of this study is to determine how these two computer-based technologies compare with regard to the accuracy with which femoral component size is established in TKA. 67 TKA were performed using CI and 30 TKA were performed using CAS by a single surgeon. CI-predicted and CAS-predicted femoral component size were compared to actual component selection. The process by which CI and CAS perform an anatomic registration was evaluated.Introduction
Methods
Single use instrumentation had a significant reduction on OR Turnover time and instrument setup/clean up time compared to traditional instrumentation. Recently, focus has shifted to improving OR efficiency by surgeons and hospital admin. The purpose of this study was to determine the effect of traditional instrumentation vs. single use instrumentation (SUI) on OR efficiency in navigated primary TKA.Summary
Introduction
Joint reconstruction remains a successful and popular surgery with advances in approaches, implants and techniques continually forthcoming. Various methods of skin closure exist to address issues in efficiency, aesthetics, and barrier to infection. While subcuticular skin closure techniques offer an aesthetic advantage to conventional skin stapling, no measurable differences have been reported. Furthermore, newer barbed sutures, such as the V-loc absorbable suture, A retrospective chart review was conducted of 278 consecutive primary joint reconstruction cases performed by a single surgeon in 12 months from July 2009 through June 2010. Pre-operative history & physical reports were evaluated for co-morbidities (i.e diabetes mellitus), smoking status and body mass index (BMI). Operative dictations by the attending surgeon provided information on the surgical procedure, use of drain, wound closure technique and type of suture/staple used for skin closure. Skin was closed by the primary surgeon and his chief resident. Wounds were closed via staple gun or subcuticular stitch (3-0 Biosyn vs V-Loc) in a consecutive manner, depending on the surgeon's preference in that period. Post-operative clinic notes were reviewed to determine the occurrence of wound complications, issuance of antibiotic prescriptions, or return to the operating room. The cohort consisted of 106 males and 161 females at an average age of 63 years (range: 18–92). Overall, there were 153 procedures at the knee (including TKA, uni-compartmental arthroplasty, patello-femoral arthroplasty) and 125 procedures at the hip (including THA and hemi-arthroplasty).Introduction
Methods & Materials
It is thought that socioeconomic status and cultural upbringing influence the patient based outcomes of total joint arthroplasty. Previous studies have shown that patients in a lower socioeconomic class had surgery at an earlier age, increased comorbidities, increased severity of symptoms at presentation, and less satisfaction with the outcome. The purpose of this study was to compare the 1) reasons for undergoing total joint replacement and 2) satisfaction with the outcome among patients in different cultures and socioeconomic categories. We hypothesized that the overall reasons for undergoing surgery would be similar among all groups. Patients undergoing total hip or knee arthroplasty were divided into groups based on their country of residence and socioeconomic status. The patients were asked to rank their reasons for undergoing surgery preoperatively from 1 to 4 according to importance. They were also asked to state how much relief of pain or improvement in function they expected to obtain. They were then asked to complete a questionnaire assessing their satisfaction with surgery 6 months post-operatively. These results were then compared across the three groups.Introduction
Method
Most surgeons utilize one of three axis options in conventional total knee arthroplasty (TKA), the transepicondylar axis (TEA), Whiteside's line (WSL) or the posterior condylar axis (PCA) with an external rotation correction factor. Each option has limitations and no clear algorithm has been determined for which option to use and when. Many surgeons believe the TEA to be the gold standard for determining rotation however it can be difficult to access intraoperatively. WSL and PCA have been used as surrogates for determining axial rotation in conventional TKA but may also be prone to error. MRI based preoperative planning systems overcome intraoperative limitations while accounting for the individual anatomy of each patient, thus helping optimize femoral component rotation. The goal of this study was to examine if coronal plane deformity had any effect on the relationship of conventional referencing options such as WSL and PCA to the TEA. Utilizing a preoperative planning software based on MRI, we compared the preoperative posterior femoral condyle resections for three different axis options in 176 TKA. The difference in bone resection amount was used to determine the rotational differences between the axis options in all knees. Assuming that the TEA was the ideal rotational axis, we compared the TEA to both WSL and PCA. A 1-sample t-test and paired t-test were then used to determine if there was a significant rotational difference between the various axis options when accounting for degree and direction of preoperative deformity in the coronal plane.Introduction
Methods
For cementless TKA, highly crosslinked UHWMPE is traditionally used with modular components because of manufacturing and sterilization complexities of monoblock metal-backed components. However, it would be very useful to have a highly crosslinked UHMWPE monoblock metal-backed cementless component to address historical clinical issues. The purpose of this study was to evaluate the wear properties of a unique process for achieving a monoblock metal-backed cementless component featuring highly crosslinked polyethylene to standard highly crosslinked UHWMPE. The knee system used for testing consisted of cobalt chrome femoral components and tibial trays (Triathlon®, Stryker Orthopaedics, Mahwah, NJ). Modular tibial inserts were machined from GUR 1020 polyethylene that was irradiated to 30 kGy and annealed three times (Modular, n=5) (X3, Stryker Orthopaedics, Mahwah, NJ). Monoblock tibias were direct compression molded to a metal substrate and then irradiated to 30 kGy and annealed three times. For the purposes of this test, the polyethylene was removed from the monoblock component and machined into a standard tibial insert (Monoblock, n=5). A 6-station knee simulator was utilized for testing (MTS, Eden Prairie, MN). All motion and loading was computer controlled and waveforms followed ISO 14243-3 [1]. Testing was conducted at a frequency of 1 Hz for 3 million cycles. The lubricant used was Alpha Calf Fraction serum (Hyclone Labs, Logan, UT) diluted to 50% with a pH-balanced 20-mMole solution of deionized water and EDTA [2]. The serum solution was replaced and inserts were weighed for gravimetric wear at least every 0.5 million cycles. Standard test protocols were used for cleaning, weighing and assessing the wear loss of the tibial inserts [3]. Soak control specimens were used to correct for fluid absorption with weight loss data converted to volumetric data (by material density). Statistical analysis was performed using the Student's t-test with significance determined at the 95% confidence level (p < 0.05).INTRODUCTION
MATERIALS AND METHODS
Traditional instrumentation relies on rigid IM rods to determine the distal femoral resection which influences size and orientation of the femoral component. Anterior femoral bowing may unexpectedly affect implant sizing. The purpose of this study was to determine the sensitivity of a flexible rod to the femoral anterior bow versus a traditional rod. A database of 93 Asian bone models from CT images was utilized. The bones were subdivided into those having proximal third, distal third, or overall femoral bows. Only the latter group was selected for further analysis, which consisted of 54 with an average bow of 98cm (±20cm). The rigid and flexible rods were placed iteratively so that the proximal portion of the rod touched the anterior cortical-cancellous boundary and no portion of the rod protruded through that boundary. The flexible rod was allowed to flex, as a substantially thin central portion flexes exclusively in the sagittal plane. The relative angle difference between the position of the flexible and rigid rod were calculated. Three femura were chosen from the subset with bows of 123cm, 100cm and 78cm. The femura showed differences between the rigid and flexible rod of 7.5°, 4.5° while no significant angle measured for the smallest bow. Implants were virtually assembled onto the bones and the greatest bowed femur's component reduced one size from the rigid to the flexible rod orientation. The results of this study show that higher bowed femura yielded larger angular deviations between rigid and flexible rods. For higher bowed femura, the flexible rod allows smaller components to be implanted. The flexible rod serves the same purpose as a conventional rod by defining the distal valgus orientation but allows component orientation in the sagittal plane closer to the femoral bow.
Idiopathic scoliosis (IS) has been associated with several genetic loci in varying study populations, reflecting the disorder's genetic complexity. One region of interest is on chromosome 17, flanking regions linked to neurofibromatosis type 1 (NF1). This region is of particular relevance because the most common osseous manifestation in NF1 is scoliosis (10–30% of patients). This alludes to a potential genetic correlation within this region affecting spinal development or stability. The objective of this research is to identify candidate genes within this region that are statistically linked to IS. An initial population of IS families recruited through approval by the institutional review board (202 families; 1198 individuals) had DNA harvested from blood, and underwent genomic screening, finemapping, and statistical analyses. We identified a specific familial subset: families with males having undergone surgery for scoliosis (17 families, 147 individuals). The initial genome-wide scan indicated that this subset was linked to chromosome 17q.11.2. The most prominent marker, D17s975, (p=0·0003) at 25.12 Mb is adjacent to the NF1 deletional region. We then analysed a custom panel of single-nucleotide polymorphisms (SNPs) extending from 18·30–31·47 Mb for linkage through Taqman SNP assay protocol. With allele specific fluorescent tags, allelic discrimination was done with real-time PCR.Introduction
Methods
The cemented mobile bearing metal backed low contact stress patellofemoral arthroplasty (LCS PFA) is a newer design belonging to the second generation of inlay type implant, based on the more successful knee arthroplasty model. The advantage is the patella can articulate with the trochlear implant as well as the femoral component of a total knee replacement (TKR). This series is a cohort of 21 patients who underwent 24 (3 bilateral) unicompartmental PFA replacements for isolated patellofemoral osteoarthritis. We have used the mobile bearing LCS PFA in all of them. There were 3 males and 18 females. Average age was 51(40-58) years. The Oxford Knee score was used to assess the results.Background
Patients
Shockwave therapy has been shown to induce osteoneogenesis in animal models. The mechanism of action is unclear, but experimental evidence suggests micro-fracture formation and increased blood flow as the most likely explanation. Several reports from Europe have suggested good results from the treatment of delayed fracture union with shock-waves. We present the results of a randomised double-blind placebo-controlled pilot study. Fourteen patients with clinically and radiologically confirmed delayed union of long-bones consented to enter the trial. The treatment group had a single application of 3000 high-energy shockwaves using the Stortz SLK unit with image intensifier control. The control group had the exactly the same treatment but with an ‘air-gap’ interposition to create a placebo-shockwave. Each patient was followed-up with serial radiographs as well as visual analogue pain scores and EuroQol assessments. All of the patients were reviewed for a minimum of three years post treatment.Background
Method
Printed plain radiographs have traditionally been the method of image transfer between hospitals, but the advent of digital imaging has revolutionised modern day radiology. It is now commonplace for compact discs to be used as the transport media for digital images, the theoretical advantages being ease of transport and storage, integration with PACS systems and the ability to perform image manipulation. However, in our tertiary referral centre for pelvic and acetabular trauma, we noted problems with digital image transfer using this method. We examined the last 25 compact discs sent to our unit for functionality on 3 separate computers. Only 17/25 discs loaded on all computers, and 2 discs failed to load on any computer. 9 of the remaining 23 discs did not allow image manipulation, and 1 disc would not allow retrieval of all the contained images. 5 of the 23 discs took longer than 5 minutes to retrieve the contained images. In summary, we classed 10 of the 25 discs as acceptable. Patient transfer to our unit was not delayed, but 4 patients underwent repeat CT scans due to incomplete imaging Digital technology has made great advances into medical imaging. Standardisation using the DICOM format for image creation has attempted to eliminate issues of compatibility, but variation in software used to produce and view images can still vary from these standards. Technical errors in the creation of discs should be eliminated at source, and it is mandatory that referring units check the functionality of discs before they are sent. In this way, the potential for delay to transfer and subsequent repeat exposure to ionising radiation can be avoided.
Our aim was to analyse radiological outcome of proximal humerus fractures treated with Philos plate and to assess its usefulness in treatment of malunion and non-union. Seventy-seven patients were treated with Philos plate (24 men and 53 women). Mean age was 61 years (15–88). There were 66 acute fractures, 6 nonunion, 4 mal-union and one periprosthetic fracture. Acute fractures included 29 two part, 30 three part and five 4 part fractures. Seven had associated dislocation. There were two head splitting fractures. Deltopectoral approach was used in all. No acute fractures were bonegrafted however all nonunions had bonegraft. Postoperative radiographs were available for review for 59. Average union time was 12 weeks (8–24). Satisfactory union occurred in 51 (86.4%). Twenty-three (39 %) fractures had inadequate reduction. Malplacement of plate was observed in 25 (42%) leading to significant malunion in 11.8%. Satisfactory union was occurred in all of last 30 patients. Nonunion occurred in 2 with infection in one. Other complications included screw penetration into glenohumeral joint, avascular necrosis, screw backing out and tuberosity detachment. Philos plate fixation was used for treatment of 6 nonunions, 4 malunions and one periprosthetic fracture with satisfactory outcome in all. Relatively high rate of complications was observed in early cases in this series. This could be attributed to the steep learning curve with this technique. Emphasis should be put on careful and adequate reduction of fracture and optimal placement of plate (about 8 mm from the tip of tuberosity) to avoid impingement and to achieve correct screw placement in the humeral head. In conclusion, Philos plate has been of benefit in management of complex fractures as well as management of non-union of proximal humerus. Quality of reduction and optimal placement of plate appear to be the two most important parameters for a successful outcome.
As part of the workup long length femur radiograph may be carried out pre-operatively in patients presenting with a proximal femur fracture in order to rule out distant metastasis in patients with a history of malignancy but also in some patients in whom a suspicion of possible distal abnormality is aroused by the configuration of the proximal fracture Using our unit’s database we identified all patients (n=689) presenting with a proximal femoral fracture between Sept 2006 and August 2007 at the Norfolk and Norwich University hospital in Norwich. Of 689 patients, 92 patients (13.2%) had long length femur radiograph performed before surgery. Indications included history of cancer (39), subtrochantric fractures (14), spontaneous fracture without any fall(2), paget s disease(1), early onset osteoporosis(1) while no clear indication was available in 35 patients. Five patients (5.5%) were found to have some abnormality. Three of the 39 patients with a history of previous cancer were found to have a distal femur metastasis. Two of the 35 patients where a clear indication was not apparent had abnormal findings: one patient had a distal femur infarction and another was found to have a distal femoral malunion. In both cases long leg films did not influence choice of implant. Of the 39 patients with a previous history of cancer, 24 had short implants (hemi-arthroplasty, intramedullary device, DHS), 14 had long implants and one patient died before the operation. Long length femoral radiographs appear to be indicated in patients with a documented history of a cancer as it helps to decide whether to use a long or short implant. However in patients without a history of malignancy, long leg films were of no value in decision making even if the configuration of the fracture was suspicious.
Compared with general anaesthesia, brachial plexus (BP) anaesthesia improves patient satisfaction and accelerates hospital discharge after ambulatory hand surgery; however, variable success rates and typical onset times up to 30 minutes have limited its widespread use. Increasing availability of high-resolution portable ultrasound has renewed interest in more proximal approaches to the BP, previously thought to carry unacceptable risk. The aim of this study was to compare the onset times of ultrasound guided supraclavicular and infraclavicular BP block in patients undergoing ambulatory hand surgery. With ethics committee approval, patients presenting for hand surgery were prospectively randomised to either supraclavicular (trunks/divisions) or infraclavicular (cords) BP block. A single experienced operator (MF) placed all blocks using ultrasound only guidance. A blinded observer (AP, SY) assessed pinprick sensory and motor block on 3-point scale (normal=2, reduced=1, absent=0) in the median, ulnar, radial and musculocutaneous nerve territories every five minutes, or until blocks were complete. A single general anaesthesia without influence from the unblended anaesthetist. Of the first 27 patients recruited, block placement details and Intraoperative data are presented in There was a trend to faster onset times and higher success in group infraclavicular, however, this did not reach statistical significance. Interim results are so far inconclusive for the superiority of one approach. Both techniques were well tolerated and had a high success rate for surgical anaesthesia.
Methicillin-resistant Staphylococcus aureus (MRSA) has become a ubiquitous bacterium in both the hospital and community setting. There are two major subclassifications of MRSA, community-acquired and healthcare-acquired, each with differing pathogenicity and management. MRSA is increasingly responsible for infections in otherwise healthy, active adults. Local outbreaks affect both professional and amateur athletes and there is increasing public awareness of the issue. Health-acquired MRSA has major cost and outcome implications for patients and hospitals. The increasing prevalence and severity of MRSA means that the orthopaedic community should have a basic knowledge of the bacterium, its presentation and options for treatment. This paper examines the evolution of MRSA, analyses the spectrum of diseases produced by this bacterium and presents current prevention and treatment strategies for orthopaedic infections from MRSA.
