Incidence and predictive factors of problems after fixation of trochanteric hip fractures with sliding hip screw or intramedullary devices.

INTRODUCTION: Hip fractures are common and disabling injuries, usually managed surgically. The most common type outside the joint capsule are trochanteric fractures, usually fixed with either sliding hip screw or intramedullary nail. Data are available in the National Hip Fracture Database (NHFD) on early failure and other major complications, but late or subtler complications may escape recording. This study sought to quantify such problems after fixation performed at 3different sites and identify their predictors. METHODS: Patients with a trochanteric fracture treated at 1 of 3 sites were identified from the NHFD over a 3-year period. Any with further, related episodes of care were identified, and reasons recorded, then age- and sex-matched with those with no such episodes. Data was collected on Arbeitsgemeinschaft für Osteosynthesefragen classification, tip-apex distance, American Society of Anesthesiologists (ASA) grade, Abbreviated Mental Test Score and pre-injury mobility. The cohorts were compared, and a binomial logistic regression model used to identify predictors of problems. RESULTS: A total of 4010 patients were entered in the NHFD across 3 sites between January 2013 and December 2015. Of these, 1260 sustained trochanteric fractures and 57 (4.5%) subsequently experienced problems leading to re-presentation. The most common was failure of fixation, occurring in 22 patients (1.7%). The binomial logistic regression model explained 47.6% of the variance in incidence of postoperative problems with ASA grade and tip-apex distance being predictive. DISCUSSION: The incidence of re-presentation with problems was around of 5%. A failure rate of less than 2% was seen, in keeping with existing data. This study has quantified the incidence of subtler postoperative problems and identified their predictors. The type of implant used was not amongst them and patients with both implants experienced problems. Fixation continues to yield imperfect results, but patient health and robust surgical technique remain important factors in a good outcome.

Quasi-static analysis of hip cement spacers.

The use of temporary hip prosthesis made of orthopedic cement (spacer) in conjunction with antibiotics became a widespread method used for treating prosthetic infections despite the fact that this method makes bone cement (PMMA) more fragile. The necessity to incorporate reinforcement is therefore crucial to strengthen the bone cement. In this study, a validated Finite Element Modelling (FEM) was used to analyze the behavior of spacers. This FEM model uses a non-linear dynamic explicit integration to simulate the mechanical behavior of the spacer under quasi-static loading. In addition to this FEM, Extended Finite Element Method (XFEM) was also used to investigate the fracture behavior of the spacers reinforced with titanium, ceramic and stainless-steel spacer stems. The effect of the material on the performance of the reinforced spacers was also analyzed. The results showed that numerical modelling based on explicit finite element using ABAQUS/Explicit is an effective method to predict the different spacers' mechanical behavior. The simulated crack initiation and propagation were in a good agreement with experimental observations. The FEM models developed in this study can help mechanical designers and engineers to improve the prostheses' quality and durability.

Changing trends in the management of intertrochanteric hip fractures - A single centre experience.

With an annual incidence greater than 65,000 in the United Kingdom, hip fractures are a common but debilitating injury predominantly affecting those over 65. Treatment is based on the anatomical location of the fracture relative to the capsule of the hip joint - fractures occurring within it are treated by arthroplasty, while extracapsular fractures are an indication for fixation. Intertrochanteric fractures are further grouped as stable (AO/OTA 31A1/A2) or unstable (31A3) which in turn governs in the current UK guidelines whether this fixation is achieved with a dynamic hip screw or intramedullary device. Anecdotally, some units are tending towards intramedullary devices for 31A2 fractures as well, a practice which from the evidence does not appear to confer benefit and carries an excess cost. We reviewed our data submitted to the National Hip Fracture Database over the last five years and identified all intertrochanteric fractures, from which cohort we identified all patients with 31A2 fractures by review of radiographs. The cohort comprised 370 patients. We then recorded age, gender, ASA grade, abbreviated mental test score, residence from where admitted, length of stay, destination on discharge and whether any further operations were required. There was no significant difference in the demographics of the groups, year-on-year, except gender mix. There was a significant, twenty-fold rise in the use of intramedullary devices between 2011 and 2015. Length of stay, length of overall episode of care, revision rates, mortality and destination on discharge were unchanged. This use is not supported by NICE guidelines and this study offers no evidence to contradict this position. We advocate all centres examine their practice to avoid a costly intervention without clinical benefit.

Motion analysis: a validated method for showing skill levels in arthroscopy.

PURPOSE: The purpose of this study was to show the validity of a motion analysis system in its ability to differentiate between surgeons and non-surgeons when performing simple arthroscopic tasks. METHODS: We divided 35 subjects into a surgeons group (n = 20) and a non-surgeons group (n = 15). The surgeons group was further subdivided based on the amount of previous arthroscopic experience. Each participant performed 2 separate simulated arthroscopic tasks while being assessed with motion analysis equipment. The time taken, total path length, and number of movements were recorded. RESULTS: A significant difference in performance was identified between surgeons and non-surgeons (P < .0001) and between senior and junior surgeons (P < .05). We identified trends toward decreased time taken and improved economy of movement with increasing arthroscopic experience. CONCLUSIONS: This study shows the validity of a motion analysis system as a means of objective assessment of arthroscopic skills in orthopaedics. The system has been shown to differentiate between non-surgeons, junior surgeons, and senior surgeons in performing simple arthroscopic tasks. CLINICAL RELEVANCE: In the context of concerns regarding reductions in training time, this study validates the use of a simple, affordable, and reliable means of objective assessment of arthroscopic skills and training in such skills. The motion analysis system could subsequently be used as an adjunct to more traditional methods of assessment when planning strategies to teach, learn, and practice arthroscopic skills in the future.

The history and future of radiostereometric analysis.

Roentgen stereophotogrammetry allows one to localize the position of an object in space using roentgen rays. For orthopaedic purposes it was developed 35 years ago by Göran Selvik, and since that time many investigators have refined the radiostereometric calculations and evaluative software. Many uses and mathematical algorithms have been developed, and advancements in computer programs and digital radiography continue to expand its capabilities. Despite these advances, improvements in the technical accuracy and type of kinematic analyses possible have been relatively modest. However, radiostereometric analysis is now easier and less time consuming to use, with a resolution in clinical practice almost equal to what could only previously be obtained under ideal laboratory conditions. The ability to measure skeletal and implant movements with high resolution in vivo images was an important progressive step for the orthopaedic community. Radiostereometric analysis has helped develop new fields in clinical orthopaedic research and continues to improve advancements in orthopaedic health care.

Guidelines for standardization of radiostereometry (RSA) of implants.

There is a need for standardization of radiostereometric (RSA) investigations to facilitate comparison of outcome reported from different research groups. In this document, 6 research centers have agreed upon standards for terminology, description and use of RSA arrangement including radiographic set-up and techniques. Consensus regarding minimum requirements for marker stability and scatter, choice of coordinate systems, and preferred way of describing prosthetic micromotion is of special interest. Some notes on data interpretation are also presented. Validation of RSA should be standardized by preparation of protocols for assessment of accuracy and precision. Practical issues related to loading of the joint by weight bearing or other conditions, follow-up intervals, length of follow-up, radiation dose, and the exclusion of patients due to technical errors are considered. Finally, we present a checklist of standardized output that should be included in any clinical RSA paper.This document will form the basis of a detailed standardization protocol under supervision of ISO and the European Standards Working Group on Joint Replacement Implants (CEN/TC 285/WG4). This protocol will facilitate inclusion of RSA in a standard protocol for implant testing before it is released for general use. Such a protocol-also including other recognized clinical outcome parameters-will reduce the risk of implanting potentially inferior prostheses on a large scale.

Sagittal plane kinematics of a mobile-bearing unicompartmental knee arthroplasty at 10 years: a comparative in vivo fluoroscopic analysis.

This study compares in vivo sagittal plane kinematics of the Oxford mobile-bearing unicompartmental knee arthroplasty (UKA) at 1 and 10 years' postsurgery (10 knees) with a fixed-bearing total knee arthroplasty (TKA) (5 knees) and the normal knee (5 knees), using dynamic fluoroscopic measurement of the patellar tendon angle. The Oxford UKA preserved normal changes in patellar tendon angle with flexion, and this was maintained at 10 years. In contrast, an abnormal pattern was seen with the TKA. The results suggest that a normal pattern of sagittal plane knee kinematics exists following Oxford medial UKA and imply that anterior cruciate ligament function is maintained in the long term.