Anecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort. Cementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers.Abstract
Introduction
Methodology
In cementless UKR, early post-operative tibial fractures are 7x more common in very small tibias. A smaller keel has been shown to reduce this fracture risk, but its effect on fixation is unassessed. This mechanical study assesses the effect of keel interference and size on sagittal micromotion of the tibial component in physiological loading positions. A high-resolution Digital Image Correlation setup was developed and validated to an accuracy of 50 micrometres. Variants of tibial components were 3D-printed: Abstract
Introduction
Method
Daycase pathways which aim to discharge patients the same day following Unicompartmental Knee Replacement have been introduced in some centres, though most continue with Standard pathways. While Daycase pathways have cost savings, recovery data comparing pathways is limited. This study aims to compare patient-reported early recovery between Daycase and Standard pathways following UKR. This study was carried out in two centres that originally used the same Standard recovery pathway for UKR. In one centre, the Standard pathway was modified into a Daycase pathway. 26 Daycase-Outpatient, 11 Daycase-Inpatient, and 18 Standard patients were recruited. Patients completed the Oxford Arthroplasty Early Recovery Score (OARS) and SF-36 (Acute) measure between Days 1–42.Abstract
Background
Method
To assess the incidence of radiological lateral osteoarthritis (OA) at 15 years after medial unicompartmental knee arthroplasty (UKA) and assess the relationship of lateral OA with symptoms and patient characteristics. Cemented Phase 3 medial Oxford UKA implanted by two surgeons since 1998 for the recommended indications were prospectively followed. A 15-year cumulative revision rate for lateral OA of 5% for this series was previously reported. A total of 163 unrevised knees with 15-year (SD 1) anterior-posterior knee radiographs were studied. Lateral joint space width (JSWL) was measured and severity of lateral OA was classified as: nil/mild, moderate, and severe. Preoperative and 15-year Oxford Knee Scores (OKS) and American Knee Society Scores were determined. The effect of age, sex, BMI, and intraoperative findings was analyzed. Statistical analysis included one-way analysis of variance and Kruskal-Wallis H test, with significance set at 5%.Aims
Methods
In cementless UKR, primary fixation of the tibial component is achieved by press-fitting a keel (i.e. with interference) into a vertical slot cut into the proximal tibia. This may adversely affect the structural integrity of surrounding bone. Early post-operative peri-prosthetic tibial fractures are 7x more common in very small knees, but the aetiology of these fractures is unknown - such sizes are rarely used in the UK but more common in Asian populations. This study explores the effect of keel-related features in fracture risk of these very small tibias. This Abstract
Introduction
Method
After remodelling, loss of bone density beside the keel of cementless UKR tibial components has been observed as a potential cause of concern. How this affects patient-reported outcomes, and further clinical implications, is unclear. This study aims to assess the effect of cementless UKR implantation on tibial bone density, and to explore its relationship to patient demographics and outcomes. This prospective study assesses 115 anterior-posterior radiographs from cementless UKR postoperatively and five years after surgery. Grey values from nine regions around each keel were collected and standardised to enable inter-radiograph comparison. Change between the post-operative and 5-year radiographs (indicating bone density) was calculated, and effect on 5-year patient demographics and pain and functional outcomes was assessed. Repeat measurements were performed by two operators to assess reliability.Abstract
Introduction
Method
Pelvic and acetabular surgery may be associated with significant blood loss because of the vascularity and anatomy of the pelvis. Concerns continue in relation to blood transfusion because of the potential for disease transmission and because of the increasing cost of providing safe blood products. The purpose of this study was to examine in a retrospective fashion the blood transfusion requirements in a consecutive series of patients undergoing peri-acetabular osteotomy for hip dysplasia. Surgery was performed under general anaesthesia with an epidural in place in the majority of cases. A cell saver was not used and no pre operative autologous blood donation was performed. In seven cases one unit of blood was drawn off immediately prior to the operation in the anaesthetic room and re-infused towards the end of the operation. This practice was discontinued when one of these units clotted and could not be re-infused. A post-operative transfusion policy was adopted where an haemoglobin (Hb) concentration of <
7.5 g/dl was an indication for transfusion. There were 19 females and 2 males. The average age was 26.6 (range 14 – 40). The average duration of surgery was 233mins (range 180 – 285min). Pre-operatively the average Hb concentration was 13.68 g/dl (range 12.3 – 16.2 g/dl). Overall 16 patients did not require any cross-matched transfusion. Two patients received one unit of blood and three received two units. If the transfusion policy had been correctly followed, 4 of these patients would not have received cross-matched blood. The average post-op Hb in those not receiving transfusion was 8.6 g/dl (range 7.3 – 9.9 g/dl). This study shows that it is possible to safely perform peri-acetabular osteotomies in most cases without blood transfusion which is important in this group of patients who are generally young and female.
