Early and mid-term results with the ATTUNE total knee replacement system compared to PFC Sigma: a prospective comparative study

The 60 patients included had 28 different secondary diagnoses, the most common of which were hypertension followed by diabetes mellitus. These secondary diseases and especially those that could have a possible influence on the ability to walk, such as polyneuropathia or Parkinson's disease, were equally distributed in both groups. The only significant difference between the two groups was the older age in the PFC group. Significantly more women were included; this gender distribution did not change significantly during the observation period (p value 0.789). Only one patient could not be re-examined after 6 months but after 5 years.

When the patients were invited by telephone for the five-year FU examination, six patients in the ATTUNE group declined a FU examination. Three of them declined due to serious illnesses (carcinoma, Parkinson's disease, recent heart attack with ongoing rehabilitation). Three patients refused to travel the long distance to our hospital. All of them stated that they were essentially satisfied with the outcome of the TKA and that no reoperation had taken place. Three patients could not be reached either by phone or by mail. One patient had died unrelated to the TKA.

In the PFC group six patients were not reexamined at 5-year FU. One patient was excluded due to reoperation following aseptic loosening of the tibial prosthesis component. One patient had died unrelated to the TKA. Two patients could not be reached by phone or by mail. Two patients were not examined because they had intermittently acquired dementia and Parkinson's disease, respectively. In both cases, however, we were informed that there were no relevant problems concerning the knee prosthesis and that no revision surgery had been performed.

Since the FU rate was approximately the same after 5 years in both groups a comparison was possible.

The frequency of complaints regarding other joints (p value 0.057) that are relevant for walking, as well as the leg axes (p value 1.0) were not significantly different preoperatively (Tables 1, 2, 3, 4 and 5).

Table 1 Clinical data preoperatively and at follow-up (FU)Table 2 Statistical analysis preoperatively, at 6 month and 5-year follow-up (FU)Table 3 Range of motion preoperatively, at 6 month and 5-year follow-upTable 4 KSS Score preoperatively, at 6 month and 5-year follow-upTable 5 HSS Score preoperatively, at 6 month and 5-year follow-up

Six months after surgery, the following data was collected: numerical pain scales (at rest, at night, when standing, when climbing stairs, when walking), duration of the postoperative use of painkillers, duration of the use of crutches after surgery, maximum possible walking time without a pause, duration of the postoperative knee swelling, ability to take part in sports and the point in time at which this was possible again postoperatively. Here the ATTUNE group showed significantly lower night pain (p value 0.041) and also a significantly shorter duration of analgetic medication postoperatively (p value 0.049). None of the other data differed significantly.

At the 5-year FU, the results had improved further in all but one patient. To the best of our knowledge, only one of the knee joints (PFC group) had been operated on again due to aseptic loosening of the tibial part of the prosthesis.

The clinical examination at 5-year FU showed no significantly different capsule-ligament loosening in extension (p value 0.731), 30° flexion (p value 1.0), 60° flexion (p value 0.492) and 90° flexion (p value 1.0). Anteroposterior stability, manually tested by means of a drawer test, was not significantly different either (p value 0.298). Radiolucent lines (RLL) at the implant–cement interface on the tibial side were not significantly different in extent and frequency (p value 0.389).

Only one patient in the PFC group showed a femoral RLL of less than 2 mm width in zone 4 according to Ewald [5] (Tables 6 and 7).

Table 6 Radiolucent lines (RLL) at the 5-years FU: Tibial component anterior view zones 1–7 according to Ewald [5]Table 7 Radiolucent lines (RLL) at the 5 years FU: Tibial component lateral view zones 1–3 according to Ewald [5]

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