Vol 44 # 2 June 2012 - Kma.org.kw

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Proximal Tibial Osteotomy in Medial Compartment Osteoarthritis: How High is High?
June 2012
Fig. 6a
Fig. 6b
Fig. 6: Anatomical changes following osteotomy of the proximal tibia
a: Medial displacement of axis and truncation after lateral closing wedge osteotomy
b: Patella infera due to contracted patellar tendon
osteotomies and for which cases the osteotomy should
be performed proximal or distal to the tibial tuberosity.
The majority of cases with all three of these techniques
are usually performed proximal to the tibial tubercle
to gain the advantage of early bone union. The
disadvantages of these osteotomies are primarily
the potential negative ramifications for future TKA.
Wedge resection of the cancellous bone in the proximal
tibia will result in truncation, particularly where there
has been a large deformity correction, and will also
remove important structural bone support which
may be required for any subsequent TKA [22] . As the
osteotomy axis is not the same as the deformity axis,
a medial translation deformity will result. Following a
closing wedge resection the patellar tendon insertion
on the tibial tuberosity moves closer to the joint line,
which generally results in patella infera secondary to
scarring in the retropatellar fat pad and the restraining
retinacular structures around the patella [11,22] .
The decision to use one over the other must
be based on the surgeon’s philosophy and clinical
experience [23] . However, HTO with medial opening
wedge has gained in popularity over recent years as
a viable alternative to traditional lateral closed wedge
osteotomy for the surgical management of MCOA [44,55-
57]
. This approach allows earlier rehabilitation, does not
require a fibular osteotomy, reduces the frequency of
neurovascular complications, and is easier to convert
to a TKA compared to the traditional closed-wedge
alternative [56,58] . However, opening-wedge HTO
can result in complications such as patella baja and
delayed union at the osteotomy site due to the bony
gap created [59] .
In open wedge osteotomy, the most reliable fixation
and augmentation techniques are still controversial.
Many methods have been used to fill the osseous gap
and these include; bone grafts (autograft or allograft),
synthetic bone substitutes with or without platelet-rich
plasma, growth factors and bone marrow stromal cells.
Gold standards seem to be locked plates and autologous
bone graft [60] . Bone graft is generally considered to be
the most successful bone filling material because of
its osteoconductive, osteoinductive and osteogenic
properties. Nevertheless, autograft harvesting involves
increased operative time and the donor site morbidity,
while allograft has lower osteoinductive properties and
carries disease transmission risk. The bone substitutes
attempt to reduce these risks, but there are still some
concerns about their resistane to compressive loads
and biological degradability. The use of bone cement
is not recommended in order to achieve a more
biological repair of the osteotomy site [61] . Encouraging
results have been reported with the use of platelet-rich
plasma, bone marrow stromal cell and growth factors,
associated both with bone grafting and with bone
substitute augmentation [60,62,63] .
Only, a few studies have compared the results after
opening-wedge and closing-wedge osteotomy [64-66] . The
current evidence-base suggests that there is no difference
in clinical outcome or incidence of complications.
Opening-wedge HTO increases the risk of a greater
posterior slope angle, patella baja and a reduced hipknee
angle compared to closing-wedge HTO during
the early post-operative period. Furthermore, longerterm,
well controlled RCT’s are now required to
develop the evidence-base. Accordingly, future study
should include an assessment of cost-effectiveness
by evaluating duration of hospital stay, rehabilitation
and time until return to occupational or sporting
pursuits [53] .