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.