TKA in difficult cases
Previous high tibial osteotomy
• HTO frequently is used to treat:
unicompartmental osteoarthritis of the knee usually as
a time buying procedure to delay eventual TKA.
• Although HTO previously was thought to have no
effect on the outcome of eventual TKA, multiple
studies have shown less successful outcomes after
HTO
TKA in difficult cases
Previous H.T.O
• Results: some authors reported lower total knee
scores for patients with HTO before TKA compaired
with similar patients without prior osteotomy.
• They found decreased postoperative ROM in the
group with HTO and poor clinical outcome due to
patellar infra and poor wound healing and deep
infection in some patients due to difficulty in
exposure and poor lateral skin flap vascularity.
TKA in difficult cases
Previous H.T.O
• Technical problems: several technical problems
unique to patients with previous HTO must be
expected and accounted for to improve results
with conversion to TKA.
1. Lateral longitudinal skin incisions must be
respected and on adequate intervening skin
bridge of at least 8 cm must be left between
new midline and old lateral incisions.
TKA in difficult cases
Previous H.T.O
2. Scaring over the lateral compartment and
infrapatellar region may be encountered
making patellar eversion and exposure more
difficult. Lateral retinacular release - vy
qudricepsplasty or a tibial tubercle osteotomy
may be necessary for exposure.
3. Because difficult ligamentous balancing, many
authors recommended PCL substitution TKA.
TKA in difficult cases
Previous H.T.O
4. After failed valgus closing wedge osteotomy of
the proximal tibia, only minimal bone resection
from the lateral plateau usually is necessary.
• The tibial cut should be referenced off the intact
medial compartment, which may leave a defect
on the lateral side of the tibia that requires bone
grafting and metal wedge or block.
TKA in difficult cases
Previous H.T.O
• Medial offset of the intramedullary canal of the
tibia relative to the center of the tibial tray is
another common problem after previous HTO and
recommended extramedullary alignment and
medialization of the tibial tray or an offset tibial
stem.
TKA in difficult cases
Correction of flexion contracture.
• Most preoperative flexion deformity improve
with appropriate soft tissue balancing for
coronal plane deformity.
• If a flexion contracture persist despite balanced
medial and lateral soft tissue the shortend
posterior structure are corrected.
TKA in difficult cases
Correction of flexion contracture.
• Another technique of correcting a flexion contracture
involve removing additional bone from the distal
femur to enlarge the narrowed extension gap.
• This technique should be used only with persistent
flexion contracture after posterior capsular release
and posterior osteophyte removal because joint line
elevation.
TKA in difficult cases
Correction of flexion contracture.
• When excessive distal femoral resection is done in an
effort to obtain extension, the knee may be stable in full
extension but with slight flexion of the knee may lack
varus valgus stability.
• In this situation, the collateral ligaments are relatively
longer than the posterior soft tissue restrains, and a
CCK type prosthesis may be necessary to resolve this
midzon instability.
• We must attention that maximal correction of a flexion
contracture occurred in the operating room and did not
improve with time.
TKA in difficult cases
Previous patellectomy.
• Early clinical studies of TKA after patellectomy reported
varied result, with most reporting pain and functional
disability because of quadriceps weakness.
• More recent studies are more encouraging, although the
type of prosthesis is debated.
• It is clear that the four bar linkage of the qudarceps
tendon - patellar tendon and cruciate ligaments is
disrupted by patellectomy and the pcl and posterior
capsule are incapable of maintaning long term sagittal
plan stability. These may experience less reliable pain
relief with TKA
TKA in difficult cases
Neuropathic arthropathy.
• Although neuropathic arthropathy generally is
considered a relative contraindication to TKA, fair
results have been reported after arthropathy for
charcot arthroplasty.
• There is obvious that these patients, frequently
required bone grafting or metal augment and some
required reoperation.
TKA in difficult cases
Neuropathic arthropathy.
• The authors emphasized proper surgical
technique including attention to limb alignment
– ligamentous balancing – bone grafting or
prosthetic augmentation for bony defect and
using revision type prosthesis.
TKA in difficult cases
Hemophilic arthropathy:
• Knee arthropathy can relieve pain in patients with
hemophilic arthropathy, but restoration of motion is
suboptimal and the risk of perioperative complication is
considerable.
• The complication include, hemorrhage, superficial skin
necrosis, three nerve palsies and deep infection.
• In these patients, the perioperative factor VIII level be
maintained at 100%.
• The most common complication after TKA in these patients
is infection up to 30%.
TKA in difficult cases
Diabetic arthropathy:
• The TKA in diabetic patients resulted in and increased
wound complication rate, increased infection and more
frequently revisions.
• The compared results of TKA in insulin dependent and non
insulin dependent diabetics showe similar complication and
diminished functional scores in both groups compared with
a control group of nondiabetic patients.
• The authors reported diabetes mellitus and advanced age
as risk factors for rehabilitation after TKA.
• They hypothesized that the proximal muscle weakness or
peripheral neuropathy associated with diabetes could
account for this association.
TKA in difficult cases
Extension contracture (stiff knee)
• Primary TKA in stiff and ankylosed knees, although
technically demanding, has been shown to provide
excellent pain relief and to significantly improve ROM.
• Stiff knees are typically defined as having less than 50
degree of motion and ankylosed knee have essentially
no motion.
• In one series 42% of cases need quadricepsplasty and
the majority of them show improvement in ROM and in
knee rating.
TKA in difficult cases
Genu recurvatum
• Genu recurvatum is an uncommon deformity that is
seldom severe except in poliomyelitis or soft tissue
abnormality such as ehlers-Danlos.
• Operative correction is obtained by under resection
of the bone ends and use a ticker components.
However paralytic types tend to recur.
• In severe cases. Its recommended to use a hinge
implants and decreased the tibial slope.