Nuffield Orthopaedic Centre

About: Nuffield Orthopaedic Centre is a healthcare organization based out in Oxford, United Kingdom. It is known for research contribution in the topics: Population & Arthroplasty. The organization has 2082 authors who have published 2920 publications receiving 145718 citations.

Radiological changes five years after unicompartmental knee replacement

Abstract: Failure of a unicompartmental knee replacement (UKR) may be caused by progressive osteoarthritis of the knee and/or failure of the prosthesis. Limb alignment can influence both of these factors. We have examined the fate of the other compartments and measured changes in leg alignment after UKR. A total of 50 UKRs was carried out on 45 carefully selected patients between 1989 and 1992. At operation, deliberate attempts were made to avoid overcorrection of the deformity. Four patients died, one patient was lost to follow-up and two knees were revised before review which was at a minimum of five years. Standard long-leg weight-bearing anteroposterior views of the knee and skyline views of the patellofemoral joint were taken before and at eight months and five years after operation. The radiographs of the remaining 43 knees were reviewed twice by blind and randomised assessment to measure the progression of osteoarthritis within the joints. Overcorrection of the deformity in the coronal plane was avoided in all but two knees. Only one showed evidence of progression of osteoarthritis within the patellofemoral joint, and this was only identified in one of the four assessments. Deterioration in the state of the opposite tibiofemoral compartment was not seen. Varus deformity tended to recur. Recurrent varus of 2 degrees was observed between eight months and five years after operation. There was no correlation between the postoperative tibiofemoral angle and the extent of recurrent varus recorded at five years. Changes in alignment may be indicative of minor polyethylene wear or of subsidence of the tibial component. The incidence of progressive osteoarthritis within the knee was very low after UKR. Patients should be carefully selected and overcorrection of the deformity be avoided.

In vitro measurement of patellofemoral force after three types of knee replacement.

Abstract: Using a new, non-invasive method, we measured the patellofemoral force (PFF) in cadaver knees mounted in a rig to simulate weight-bearing. The PFF was measured from 20° to 120° of flexion before and after implanting three designs of knee prosthesis. Medial unicompartmental arthroplasty with a meniscal-bearing prosthesis and with retention of both cruciate ligaments caused no significant change in the PFF. After arthroplasty with a posterior-cruciate-retaining prosthesis and division of the anterior cruciate ligament, the PFF decreased in extension and increased by 20% in flexion. Implantation of a posterior stabilised prosthesis and division of both cruciate ligaments produced a decrease in the PFF in extension but maintained normal load in flexion. There was a direct relationship between the PFF and the angle made with the patellar tendon and the long axis of the tibia. The abnormalities of the patellar tendon angle which resulted from implantation of the two total prostheses explain the observed changes in the PFF and show how the mechanics of the patellofemoral joint depend upon the kinematics of the tibiofemoral articulation.

Comparative responsiveness and minimal change for the Oxford Elbow Score following surgery

Abstract: To assess the responsiveness and minimal change for the Oxford Elbow Score (OES) using anchor- and distribution-based approaches. A prospective observational study of 104 patients undergoing elbow surgery at a specialist orthopaedic hospital was carried out. Patients completed the OES and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires (both scored on a 0 to 100 scale) pre- and 6 months post-surgery. Transition items (used as anchors) assessed perceived changes following surgery. Indicators of responsiveness were the effect size; the anchor-based minimal clinically important difference (MCID) and best cut-point on the receiver operator characteristic (ROC) curve; and the distribution-based minimal detectable change (MDC). The three elbow-specific OES scales (Function, Pain, Social-Psychological) produced generally larger effect sizes (0.79, 1.14 and 1.18, respectively) than the upper-limb-specific DASH scale (0.76). Clear associations were observed between transition items and all OES and DASH scores (all r > |0.35|). The MCIDs for the OES Function scale and the DASH were similar (≈10), but were larger for the OES Pain and Social-Psychological scales (≈18), reflecting their lower (i.e. poorer) baseline scores and larger effect sizes. The MCIDs were, however, only consistently larger than the MDCs for the OES Pain domain. The OES Function scale and the DASH performed similarly on ROC analysis, but with the OES Pain and Social-Psychological scales demonstrating superior efficiency. For elbow surgery, the 12-item three-scale OES is highly responsive to 6-month post-operative outcomes, with its performance being generally better than that of the 30-item one-scale DASH. Study estimates of minimal change for the OES may be useful for informing sample size calculations and interpreting outcomes in future clinical trials.