An increased tibial tubercle–trochlear groove
(TT-TG) distance is related to patellar maltracking and instability.
Tibial tubercle transfer is a common treatment option for these
patients with good short-term results, although the results can
deteriorate over time owing to the progression of osteoarthritis.
We present a ten-year follow-up study of a self-centring tibial
tubercle osteotomy in 60 knees, 30 with maltracking and 30 with
patellar instability. Inclusion criteria were a TT-TG ≥ 15 mm and
symptoms for >
one year. One patient (one knee) was lost to follow-up
and one required total knee arthroplasty because of progressive
osteoarthritis. Further patellar dislocations occurred in three
knees, all in the instability group, one of which required further
surgery. The mean visual analogue scores for pain, and Lysholm and
Kujala scores improved significantly and were maintained at the
final follow-up (repeated measures, p = 0.000, intergroup differences
p = 0.449). Signs of maltracking were found in only a minority of
patients, with no difference between groups (p >
0.05). An increase
in patellofemoral osteoarthritis was seen in 16 knees (31%) with
a maximum of grade 2 on the Kellgren–Lawrence scale. The mean increase
in grades was 0.31 (0 to 2) and 0.41 (0 to 2) in the maltracking
and instability groups respectively (p = 0.2285) This self-centring tibial tubercle osteotomy provides good results
at ten years’ follow-up without inducing progressive osteoarthritis. Cite this article:
We have examined the relationship between the size of the flexion gap and the anterior translation of the tibia in flexion during implantation of a posterior cruciate ligament (PCL)-retaining BalanSys total knee replacement (TKR). In 91 knees, the flexion gap and anterior tibial translation were measured intra-operatively using a custom-made, flexible tensor-spacer device. The results showed that for each increase of 1 mm in the flexion gap in the tensed knee a mean anterior tibial translation of 1.25 mm (SD 0.79, 95% confidence interval 1.13 to 1.37) was produced. When implanting a PCL-retaining TKR the surgeon should be aware that the tibiofemoral contact point is related to the choice of thickness of the polyethylene insert. An additional thickness of polyethylene insert of 2 mm results in an approximate increase in tibial anterior translation of 2.5 mm while the flexed knee is distracted with a force of between 100 N and 200 N.
