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Closing wedge varus tibial osteotomies: Surgical technique and long term results
109
But this procedure was performed even in large
valgus deformities and an overcorrection was
aimed leading to joint obliquity and shear
stresses of the femur on the tibia [2, 3, 4, 6]. In
a series of opening wedge HTVO Marti
et al.
reported 9% of common fibular nerve palsy
[6]. Thanks to these findings, more recent
studies were mainly focused on DFVO.
Nevertheless, closing or opening wedge DFVO
have had a complication rate of 63% including
stiffness, non or delayed union and hardware
failure [19]. In a series of lateral opening wed
ge, Jacobi et al reported 86% of impingement
between the plate and the iliotibial band [20].
In our series, we did not record any major
complication such as stiffness, non or delayed
union and nerve injury. Complication rate was
23% (7 cases/31) including hardware removal
(4 cases), hardware removal with partial
menisectomy (2 cases) and one symptomatic
joint line obliquity requiring early total knee
replacement.
If both femoral and tibial osteotomies provide
good long term functional results, the final
alignment after such procedure is still
controversial. In the early series of HTVO, an
over correction was aimed leading to
overloading of the medial compartment and
early failure [1, 5]. Thanks to these findings,
some authors stated that ideal correction after
osteotomy for valgus knees should be a normal
mechanical alignment or a slight hypo
correction [1, 5]. There is no equivalence for
the “Fujisawa Point” for varus osteotomy [21].
A loading point just medial to the medial tibial
spine was also proposed [7]. In our series,
normal alignment was aimed for symptomatic
valgus knees. In case of normal mechanical
axis, the goal was a varus axis under 5°.
Thus, the type of the osteotomy (HTVO or
DFVO) depends on the location of the valgus
deformity [6]. According to Hoffman
and al.
,
genu valgum is located on the femur in 22%, in
the tibia in 45% and both in 33% [22].Alghamdi
and al
also recorded 53% of tibia valga in
ostearthritic valgus knees [23]. Paley and
Tetsworth described a Malalignment Test
(MAT) to analyse the origin of the deformities
of the limb [12]. Normal values for tibial
(MPTA) and femoral (mLDFA) mechanical
axis are between 85° and 90°. Normal value for
JLCA is between 0° and 3°. A JLCA of more
than 3° is associated with medial collateral
ligament laxity or bone loss on the lateral
compartment. The importance of the joint
laxity could be evaluated by monopodal and/or
bipodal stance views and bony deformity could
be evaluated by non weight bearing views. In
case of medial collateral ligament laxity, some
authors proposed MCL thightening [3, 24]. In
our series, all patients had a JLCA between 0°
and 3° preoperatively.
According to Coventry a
nd al
and Shoji
and
al.
, DFVO should be done when the valgus
deformity exceeds 6° or if the planned
postoperative joint line obliquity exceeds 10°.
To be more precise, femoral contribution in
valgus deformity should be considered when
the mechanical femoral angle is less than 84°.
In our series, early failure occurred twice when
the valgus deformity was on the femur with a
normal or varus tibial deformity.
HTVO may lead joint line obliquity, but DFVO
is efficient only in extension, not in flexion and
leads to internal rotation in flexion. On the
opposite, HTVO is efficient both in flexion and
in extension [5].
As a conclusion, closing wedge HTVO for
lateral osteoarthritis provides good long term
functional and clinical results with a low
complication and revision rate. However,
conditions for a good result are a preoperative
femoral valgus deformity under 6°, a normal
postoperative axis, a postoperative joint line
obliquity under 10°. If the femur valga exceeds
6°, femoral or combined tibial and femoral
osteotomies should be considered.