Corail implants have shown to give good results in elective total hip replacements (THR) and in hemi-arthroplasties. Pre-operative planning to identify the correct size of the Corail implant is vital for good post-operative outcomes. An undersized implant can lead to subsidence. The aim of the study was to review the incidence of subsidence. Post-operative radiographs of trauma patients (n=39) and elective (n=45) patients who had Corail femoral implants were reviewed. The implant-to-canal (I:C) ratio were calculated at the given 50% and 70% levels of the Corail implant. Follow up radiographs were reviewed to identify subsidence. The average age of patients was 80.3 years (range 66–93 years) in hemi-arthroplasties and 61 years (range 18–88) in elective THRs. The implant to canal (I:C) ratio at the 50% and 70% levels in trauma patients were 0.77 (range 0.54 – 0.97) and 0.81 (range 0.59 – 0.94) respectively. In elective patients, the ratios at the 50% and 70% marks were 0.77 (range 0.57 – 0.98) and 0.81 (0.56 – 0.95). One case of subsidence was seen in a collarless implant and I:C ratios at 50% and 70% were 0.57 and 0.56. A larger study is required to determine the reliability of this novel ‘implant:canal’ ratio to predict incidence.
CT based systems that are used to create custom components and custom cutting guides in total knee arthroplasty (TKA) have variable methods for accounting for the thickness of remaining cartilage that may influence component sizing and bone resection. Little information has been published about the thickness of this cartilage, especially on the posterior femoral condyles. Failure to account for this cartilage may lead to under-sizing of the femoral component, or a reduction in the posterior condylar offset that may adversely affect flexion after TKA. This IRB approved, retrospective study included 140 consecutive patients who underwent primary TKA. The medial and lateral posterior condylar bone cuts were performed in the usual manner with mechanical instruments. The resected specimen was sectioned in the sagital plane and the cartilage thickness was measured at the mid portion to the nearest millimeter.Introduction
Methods
While prosthesis survival in Total Knee Arthroplasty (TKA) exceeds 90% at 10 year, failures do occur. One area of concern has been the potential for metal allergy or metal sensitivity causing persistent pain, swelling or early failure of the implant in some patients. Definitive tests for diagnosing metal allergy and metal sensitivity have not been developed and this field remains controversial. In most cases where metal sensitivity is a concern, metals such as Chromium and Nickel are implicated. Despite the lack of good diagnostic tests for identifying these patients, several orthopedic prosthesis manufacturers have developed implants made of Titanium or ceramic designed for use in patients where concerns exist regarding metal allergy. In the absence of good diagnostic tests, use of these devices in patients that self identify is one option. To date, little information has been presented about the incidence of self reported metal sensitivity in patients undergoing joint replacement. This study was undertaken to determine the incidence of self reported metal allergy or sensitivity in patients undergoing total knee arthroplasty. An IRB approved, retrospective chart review was performed in a consecutive series of 194 patients who had undergone TKA at one institution, with one surgeon. Self reported metal sensitivity and allergy had been routinely elicited from each individual who had not undergone implantation of a previous metallic device, during pre-operative consultation.Introduction
Methods
Patellar resurfacing during Total Knee Arthroplasty (TKA) is controversial. Problems unique to patellar resurfacing may be influenced by available patellar component design. These issues include; over-stuffing (the creation of a composite patellar-prosthesis thickness greater than the native patella) that may contribute to reduced range of motion; and over-resection of the native patellar bone that may contribute to post-operative fracture. Prosthesis design may play a role in contributing to these problems. Component diameter and thickness are quite variable from one manufacturer to another and little information has been previously published about optimal component dimensions. This anatomic study was performed to define the native patellar anatomy of patients undergoing TKA, in order to guide future component design. This retrospective, IRB approved study reviewed 797 Caucasian knees that underwent primary TKA by a single surgeon. Data recorded for each patient included: gender; patellar thickness before and after resurfacing, and the size of the component that provided the greatest patellar coverage without any overhang. The residual patellar bone thickness after resection was also calculated.Introduction
Methods
