TKA in difficult cases Previous high tibial osteotomy HTO frequently is used to treat: unicompartmental osteoarthritis of the knee usually as a time buying

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


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.


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.


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.


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.


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.


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.



• 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.



• 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.


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


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.


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 casesHemophilic 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%.


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.


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.


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.

Documents

TKA in difficult cases Previous high tibial osteotomy HTO frequently is used to treat: unicompartmental osteoarthritis of the knee usually as a time buying