Abstract
Introduction
Total knee arthroplasty has become an established operation. Cemented fixation of the components has given satisfactory results and is accepted as the gold standard. Cement failure with aseptic loosening, however, is a possible long term complication. This is particularly important in view of the increasing number of younger patients who can benefit from this procedure. Hence the attraction of using implants fixed by direct osseointegration of bone into the implant, by passing the potential weak link of the cement.
Objectives
The objective of this study was to determine the mid-term clinical, radiological and functional outcomes after navigated cementless and cemented implantation of total knee arthroplasties without patella resurfacing done by a single surgeon.
Methods
A mixed patient cohort of 97 consecutive patients who received a navigated e.motion((BBraun Aesculap, Tuttlingen) mobile bearing knee was invited for follow up after a minimum of 5 years. All the procedures were navigated using the Orthopilot(system. The uncemented components were manufactured with a surface coating of plasma sprayed titanium with a pore size between 50 to 200(m to facilitate osteointegration (Plasmapore(). 63 patients followed the invitation and thereof 46 knees were cementless and were reviewed clinically and radiologically. The Knee Society Score (KSS), clinical (KSKS) and functional (KSFS), the Oxford knee score (OKS), complications and revisions were assessed. A radiological determination of potential radiolucencies was done.
Results
In the cementless knees, there was a statistically significant improvement in the KSS (KSFS/KSKS) from an average preoperative 74 (36/39) to 185 (90/94) points after an average of 61 months follow-up. The range of motion showed a statistically significant increase from 94° to 110°. The average Oxford score in these patients showed a statistically significant improvement from 45 to 17 points. (p<0.05). All results slightly deteriorated during the period between 2 and 5 years after the index operation. Radiographic examination showed no instances of osteolysis. There were no radiolucent lines adjacent to the femoral implants and none along the coated areas of the tibial implants. For all 97 patients (71 uncemented knees) there was a total of 24(19) complications, 2(2) reoperations and 4(3) revisions. None of the adverse and serious adverse events was prosthesis related. The overall survival rate was 95.9% (cementless: 95.7%). The number of cemented knees was too small for statistical analysis.
Conclusion
The Navigated cementless floating platform e.motion total knee replacement gave good clinical and functional results in the medium term. Radiographs showed excellent osteointegration of the implants. These results compared favourably with historical results of both cementless and cemented knees. The survival rate is not significantly different for hybrid (96.1%) and cementless TKA (95.7%) but longer-term follow up results with controls have to be assessed in the future.
