Insufficient arthroscopic cuff tear reconstruction leading to massive osteoarthritis and irreparable rotator cuff tears might be salvaged by implantation of an inverted total shoulder prosthesis Delta in the elderly. However, despite the generally high success rate and satisfying clinical results of inverted total shoulder arthroplasty, this treatment option has potential complications. Therefore, the objective of this study was a prospective evaluation of the clinical and radiological outcome after a minimum of 2 years follow-up of patients undergoing inverted shoulder replacement with or without prior rotator cuff repair. Sixty-eight shoulders in 66 patients (36 women and 30 men) operated between February 2002 and June 2007 with a mean age of 66 years (ranging from 53 to 84 years) were first assessed preoperatively and then at minimum 2 years follow-up, using the Constant score for pain, Constant Shoulder Score, Oxford Shoulder Score, UCLA Shoulder rating scale, DASH Score, Rowe Score for Instability and Oxford Instability Score. 29 patients (Group A) had undergone previous shoulder arthroscopy for cuff tear reconstruction at a mean of 29 months (range 12 to 48 months) before surgery and 39 patients (Group B) underwent primary implantation of an inverted total shoulder prosthesis Delta. Any complications in both groups were assessed according to Goslings and Gouma.Introduction
Patients and Methods
Unicompartmental knee arthroplasty (UKA) in patients with isolated medial osteoarthritis of the knee is nowadays a standard procedure with good results, especially with the minimally-invasive approach. However, the survival rate of the unicompartmental knee prostheses is inferior to that of total knee prostheses. Therefore, further studying of UKA is still necessary. In most mobile bearing designs the femoral component has a spherical surface and therefore its positioning is not crucial. The role of the tibial slope in UKA has not been investigated so far. The manufacturers recommend tibial slopes with values between 10° positive slope and 5° negative slope. Most surgeons try to reconstruct the anatomical slope with a high failure by measuring the slope on x-rays. The aim of this study was to investigate the influence of the tibial slope on the wear rate of a medial UKA. In vitro wear simulation of medial mobile bearing unicompartmental knee prosthesis with a spherical femoral surface (Univation ®) was performed with a customized four-station servo-hydraulic knee wear simulator (EndoLab GmbH, Thansau, Germany) reproducing exactly the walking cycle as specified in ISO 14243–1:2002(E). The tibial tray was inserted with 2 different medial tibial slopes: 0°, 8° (n=3 for each group). The lateral tibial slope of the space-holder was not changed (0° for every group). We performed a total of 5 million cycles for every different slope, the gravimetric wear rate was determined gravimetrically using an analytical balance every 500 000 cycles according to the ISO 14243–2.Introduction
Materials and methods
