Aims

The mid-term results of kinematic alignment (KA) for total knee arthroplasty (TKA) using image derived instrumentation (IDI) have not been reported in detail, and questions remain regarding ligamentous stability and revisions. This paper aims to address the following: 1) what is the distribution of alignment of KA TKAs using IDI; 2) is a TKA alignment category associated with increased risk of failure or poor patient outcomes; 3) does extending limb alignment lead to changes in soft-tissue laxity; and 4) what is the five-year survivorship and outcomes of KA TKA using IDI?

Method: One hundred and twenty-eight knees treated by carbon fibre resurfacing pads and rods for grades III and IV articular cartilage lesions were assessed arthroscopically, with an average follow-up of 22.6 months. The mean age was 37.4 years. Results were scored by an independent observer, using the ICRS scale (1–12) as grade I, normal; grade II, nearly normal; grade III, abnormal; grade IV, severely abnormal.

Results: The mean scores were: medial femoral condyle, 10.5; lateral femoral condyle, 9.76; trochlea, 9.9; patella 9.4. Grades I & II scores for rods were: medial femoral condyle, 95.1%; lateral femoral condyle, 76.0%; trochlea, 86.1%; patella, 89.7%. The pads were used in significant numbers only on the patella. Of the total, 76.7% of the repairs were for grades I and II changes.

Patellar resurfacing was combined with realignment and an ‘anteriorisation’ procedure in 77 knees. We found that 96.7 % of repairs for grades I & II disease were seen with rods on the patella, when combined with a mechanical correction, compared with 66.0%, when used on the patella without a realignment procedure. However, when the use of pads was combined with mechanical corrections the score was 76% and a lower proportion were grade I repairs (13%) than with rods (30.0%).

The mean Waddell Score (0–4) was 2.9. From the survey 81.8% regarded the procedure as worthwhile and 9.1% were doubtful.

Conclusions: We concluded that carbon fibre resurfacing was an effective method of treating articular cartilage defects. Rods were more effective than pads and are recommended as the universal method. The results were improved by the correction of abnormal biomechanical alignment. Stabilisation of the cartilage defects resolved synovitis.