The early radiological results of the uncemented Oxford medial compartment knee replacement

Abstract

We carried out a prospective investigation into the radiological outcomes of uncemented Oxford medial compartment unicondylar replacement in 220 consecutive patients (231 knees) performed in a single centre with a minimum two-year follow-up. The functional outcomes using the mean Oxford knee score and the mean high-activity arthroplasty score were significantly improved over the pre-operative scores (p < 0.001). There were 196 patients with a two-year radiological examination performed under fluoroscopic guidance, aiming to provide images acceptable for analysis of the bone-implant interface. Of the six tibial zones examined on each knee on the anteroposterior radiograph, only three had a partial radiolucent line. All were in the medial aspect of the tibial base plate (zone 1) and all measured < 1 mm. All of these patients were asymptomatic. There were no radiolucent lines seen around the femoral component or on the lateral view. There was one revision for loosening at one year due to initial inadequate seating of the tibial component. These results confirm that the early uncemented Oxford medial unicompartmental compartmental knee replacements were reliable and the incidence of radiolucent lines was significantly decreased compared with the reported results of cemented versions of this implant. These independent results confirm those of the designing centre.

Cementless fixation in Oxford unicompartmental knee replacement

“…21 These findings are similar to those of previously published studies of cementless OUKRs in smaller numbers of patients. 10,12 At a mean of 38.2 months (19 to 88) postoperatively, the rate of complications and revision is not significantly different from that in the previously published series of cemented OUKRs, and functional outcomes are equivalent.…”

“…Femoral radiolucencies were assessed on the lateral radiograph by examining the flat area at the posterior femoral condyle and the area around the femoral pegs. 12 The extent of tibial radiolucencies was assessed using the AP radiograph by dividing the area under the tibial tray into six zones, and radiolucencies were described as partial or complete, depending on whether all six zones were involved (Fig. 1).…”

“…This is supported by a singlecentre cohort study demonstrating lack of progression of radiolucent lines between one and two years. 12 However, these studies were insufficiently large to evaluate complications or to assess the true incidence of complete radiolucency accurately, or to identify contraindications to cementless fixation.…”

Cemented versus cementless Oxford unicompartmental knee arthroplasty using radiostereometric analysis

“…A low prevalence of radiolucency beneath cementless tibial components has previously been shown. 10 Cementless fixation of a TKA has a chequered history and is not used routinely in most centres, as it is associated with a high rate of revision. [11][12][13] The NJR reported that only 6.7% of all TKAs in England and Wales were cementless, with no differentiation between the types of cementless fixation, and had a significantly greater risk of revision at eight years than cemented TKA.…”

A semi-automated measurement technique for the assessment of radiolucency

“…Each surgeon then assessed the radiographs for radiolucency in their own time on computers of their choice; all the computers chosen were office-based systems. The tibial tray was considered to be divided into seven zones, previously defined by Hooper et al [13] (figure 1), and the surgeon recorded whether radiolucency was present or not in each zone. In order to best reproduce the clinical situation, the surgeons were not given any guidance as to how to identify radiolucency within the zones; they were just presented with the radiographs, and a form to complete containing an image illustrating the location of the zones.…”