Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice. This retrospective cohort study included consecutive patients undergoing TKA at a specialist centre in the UK between November 2010 and December 2012. Data were collected using a bespoke electronic database and cross-referenced with national arthroplasty audit data, with variables including: preoperative characteristics, intraoperative factors, complications, and mortality status. Patient-reported outcome measures (PROMs) were collected by a specialist research team at ten years post-surgery. There were 536 TKAs, of which 308/536 (57.5%) were in female patients. The mean age was 69.0 years (95% CI 45.0 to 88.0), the mean BMI was 32.2 kg/m2 (95% CI 18.9 to 50.2), and 387/536 (72.2%) survived to ten years. There were four revisions (0.7%): two deep infections (requiring debridement and implant retention), one aseptic loosening, and one haemosiderosis.Aims
Methods
We report ten-year clinical and radiological
follow-up data for the Sigma Press Fit Condylar total knee replacement system
(Sigma PFC TKR). Between October 1998 and October 1999 a total of
235 consecutive PFC Sigma TKRs were carried out in 203 patients.
Patients were seen at a specialist nurse-led clinic seven to ten
days before admission and at six and 18 months, three, five and
eight to ten years after surgery. Data were recorded prospectively
at each clinic visit. Radiographs were obtained at the five- and
eight- to ten-year follow-up appointments. Of the 203 patients,
147 (171 knees) were alive at ten years and 12 were lost to follow-up.
A total of eight knees (3.4%) were revised, five for infection and
three to change the polyethylene insert. The survival at ten years
with an endpoint of revision for any reason was 95.9%, and with
an endpoint of revision for aseptic failure was 98.7%. The mean
American Knee Society Score (AKSS) was 79 (10 to 99) at eight to
ten years, compared with 31 (2 to 62) pre-operatively. Of 109 knee
with radiographs reviewed, 47 knees had radiolucent lines but none
showed evidence of loosening. Cite this article:
We report the general mortality rate after total
knee replacement and identify independent predictors of survival. We
studied 2428 patients: there were 1127 men (46%) and 1301 (54%)
women with a mean age of 69.3 years (28 to 94). Patients were allocated
a predicted life expectancy based on their age and gender. There were 223 deaths during the study period. This represented
an overall survivorship of 99% (95% confidence interval (CI) 98
to 99) at one year, 90% (95% CI 89 to 92) at five years, and 84%
(95% CI 82 to 86) at ten years. There was no difference in survival
by gender. A greater mortality rate was associated with increasing
age (p <
0.001), American Society of Anesthesiologists (ASA)
grade (p <
0.001), smoking (p <
0.001), body mass index (BMI)
<
20 kg/m2 (p <
0.001) and rheumatoid arthritis
(p <
0.001). Multivariate modelling confirmed the independent
effect of age, ASA grade, BMI, and rheumatoid disease on mortality.
Based on the predicted average mortality, 114 patients were predicted
to have died, whereas 217 actually died. This resulted in an overall
excess standardised mortality ratio of 1.90. Patient mortality after
TKR is predicted by their demographics: these could be used to assign
an individual mortality risk after surgery.
