208 / 242
C. Murphy, T. Aїt Si Selmi, M. Bonnin
208
revision rate for Oxford Unicompartmental
knees that reduced from 20 to 7% if the surgeon
performed more than 23 cases per year [37],
while in the Norwegian registry series hospitals
performing 25-50 UKAs per year had a 40%
decrease in revision rate compared to those
performing less than 10 procedures per year
[19]. The numbers of revisions from UKA to
TKA are highlighted in Table 2 under (U2Ts)
where presented, and numbers range from one
single revision [51] to 678 Medial UKAs to
TKA [36].
Laterality and survival
One of the problems with analysis of joint
register data pertaining to UKA has been a
failure to consider medial and lateral implants
separately, for both survival and mode of
failure. Early studies report five to ten year
failure rate for Lateral UKA of around 82% [4,
21, 24]. Up to ten year survival rates of 92%
and 98% have been reported [2, 8, 39], and
both Sah and Pennington report series with
100% survival at a mean of 5.2 and 12.4 years
respectively [50, 54].
When considered together, Lateral UKA
account for a low proportion of Revised UKAs
[7, 13, 14, 45, 61], making interpretation of
data difficult, ranging between 4% [51] to 21%
[12]. Lewold et al reporting on the Swedish
register were the first to stratify indication for
revision by side, finding broadly similar
indications for revision [36]. The study by
Table 3: Conversion of UKA to TKA; use of implants, grafts, augments.
Author
Year U2T
Comments
Barrett
7
1987 29 27 CR TKR, Half Stem/Augment +with screw +cement/Bone graft
Chatain
13
2004 54 39 TKR, 14 Rev TKR including stemmed, 1 hinged.
Saldanha
55
2007 36 6 constrained, 2 semi-constrained, 6 stems, 2 augments, 2 Bone
graft
Lewold
36
2008 778 750 TKR (655 Medial, 95 lat), 28 constrained (23 medial 5 lateral)
Oduwole
43
2010 13 7 TKR, 6 requiring Stem/Augment/Bone graft
Pandit
48
2011 19 17 TKR, 2 Rev TKR Stems &/Wedges
Chou
14
2012 33 Stems 12, wedges 7
Pearse
49
2012 205 Any revision prostheis 28%, Stems 22%, wedges 14%
Robb
52
2013 24 Stemmed 8, Tibial augments 3, hinged 1
Sierra
60
2013 175 PS 88, CR 81, constrained 6, Augments 53, Stems 67
Saragaglia
56
2013 371 67% PS, 33% CR, 4% Rotating hinge.
Bone Loss: F41%, T50%,
Bone Graft F 31, T 112 (47% morcelised, 38% corticocancellous,
10% segmental allograft)
Augments: F2, T25, Stem: 18F, 18T
U2T
Number of conversions of UKA to TKA.
PS
Posterostabilised
CR
Cruciate retaining
F
Femur
T
Tibia
Rev
Revision