Porous metal surfaces have been a popular option for acetabular component fixation in total hip arthroplasty (THA). New THA component designs are introduced periodically with the expectation of better wear properties and survivorship. Since its approval for use in 2002 there have been few clinical outcome studies published on the Pinnacle acetabular cup system. We hypothesised that the hemispherical porous coated Pinnacle acetabular cup system with a range of cup options and bearing surfaces would give us predictably good fixation and survivorship at five years post implantation. A total of 1391 Pinnacle acetabular cups (De Puy, a Johnson & Johnson company, Warsaw IN) were implanted between the period March 2003 to August 2011 by four senior surgeons. There were a total of 29 patients requiring revision surgery. Of these revisions, 23 were excluded from the final analysis. Sixteen were for early infection requiring debridement of the hip joint and exchange of the modular liner and femoral head. Five patients sustained femoral peri-prosthetic fractures requiring further surgery with retention of the acetabular component in all cases. Of the remaining 8 revision cases, only 6 had more than two years follow-up. All patients had pre and post-operative Harris hip scores, WOMAC and SF-12 scores. All patients were assessed with serial radiographs immediately post-operatively, 3 months, 1 year, 2 years, every 2 years thereafter. Component migration and revisions (excluding infection and peri-prosthetic fractures) are reported as failures. Post-operative radiographs were evaluated for component migration. Kaplan-Meier survivorship curves were drawn to show survivorship for cup type and bearing type.Objectives
Materials and Methods
The patella provides a mechanical advantage to the knee extensor mechanism. Patellectomy, performed for trauma or patellofemoral arthrosis, does not preclude the development of tibiofemoral arthrosis. Total knee arthroplasty is the mainstay of treatment for tibiofemoral arthrosis. The purpose of this study was to evaluate the outcomes of total knee arthoplasty in patients who previously underwent patellectomy. A retrospective analysis was completed on a prospectively collected database to identify all patients who underwent total knee arthroplasty following a previous patellectomy. Sixty-one total knee arthroplasties in 57 patients were identified. Patient demographics as well as functional outcome scores, including WOMAC and Knee Society Scores, were evaluated.Purpose
Method
Many authors have recommended undercorrection of the deformity when carrying out unicompartmental knee arthroplasty (UKA). The isolated effect of alignment of the knee on the outcome of UKA has, however, received little attention. We reviewed 185 UKAs at a minimum of five years after surgery. They had been carried out by a single surgeon using metal-backed tibial components in the management of arthritis of the medial compartment. We measured the tibiofemoral angle (TFA) before and at four months after operation and at the most recent assessment. The amount of correction of the TFA and any subsequent loss were recorded. While adjusting for the effects of age, weight and gender of the patients and the type and thickness of the implants, the mean correction was significantly less for those with a Marmor rating of failure (6.8°) than for those rated excellent (9.2°). The mean correction was also significantly less for patients with a Marmor rating of failure (6.8°) than for those rated poor (11.1°). The mean correction for the UKAs which were revised (6.6°) was significantly less than for those not revised (9.1°). Additionally, revised UKAs had a significantly higher percentage (63%) of thinner tibial implants (<
8 mm) than the surviving UKAs (27%). These findings suggest that undercorrection of the TFA in UKA of the medial compartment should be avoided, particularly if a thin tibial polyethylene insert is used.