vascular malformation of a unilateral lower limb with severe arthritis of the same knee joint is a rarity . baskerville has reported 16% rate of deep vein thrombosis ( dvt ) and 14% risk of pulmonary embolism in patients with klippel trenaunay syndrome.123 same view is endorsed by muluk et al.4 silva and luck have reported high rate of late infections with 10-year survival of infection free implants being 77% in hemophilic knees undergoing tka.5 we report a case of early onset degenerative knee arthritis with vascular malformations in which navigated tka was performed successfully . only two cases are reported in the literature , which have some resemblance to our case.67 our case is unique to have intramedullary lesions in the femur to complicate the management . a 30-year - old woman working as a clerical staff , requiring daily commuting by crowded trains , was suffering from left knee pain for last 6 years . her difficulty in walking had worsened since last 6 months and did not respond to nonsurgical management . she also had a history of intermittent rectal bleeding . on examination , there were cutaneous and soft tissue hemangiomas alongwith varicose veins throughout the affected left lower extremity from hip to toes , mainly on the gluteal region , posterior thigh , popliteal fossa , calf and foot [ figure 1a - d ] . she had a flexion deformity of 20 with further flexion up to 40. the movements were very painful in the available range of motion ( rom ) . clinical photographs of patient showing ( a - d ) the extent of superficial vascular lesions from left hip to toes with flexion contracture of the left knee ( a and b ) x - rays of left knee anteroposterior and lateral views showing severe degeneration and the phleboliths ( arrow ) radiographs [ figure 2 ] showed severe degenerative tricompartmental arthritis in the left knee joint with bone loss from the lateral femoral condyle and the lateral tibial plateau . magnetic resonance imaging and magnetic resonance venogram [ figure 3 ] of the left lower limb with pelvis showed vascular malformation ; mostly multifocal hemangiomas involving superficial and deep soft tissues of the entire left lower limb , pelvic region , rectum and left femur . her coagulation profile was normal ( bleeding time -5 s , clotting time -3 min , prothrombin time-13 s , international normalization ratio-1.1 , activated partial thromboplastin time-28 s , factor viii-110% and factor ix-100% ) . trenaunay syndrome , but it can be called as a variant of klippel  trenaunay syndrome . magnetic resonance venogram showing vascular malformation in intra medullary , subcutaneous and deep soft tissues with phleboliths surgery was done under spinal anesthesia8 with tourniquet and exsanguination of limb using eshmarch bandage . computer - assisted navigated surgery was done due to intra medullary involvement of the lesions [ figure 3 ] . two thin threaded pins with bicortical holds were used to fix the clamps carrying the tracker ball arrays . the pin hold was good and remained well till the end of the surgery as the bone quality was good on both femoral as well as tibial sides . the synovium was grey - black with an orange tinge of the remaining articular cartilage . femoral bone cuts also revealed vascular malformations in the bone which were curetted out [ figure 4 ] . ( a and b ) intra operative photographs showing the synovium , femoral condyles and cut distal femur cemented tka using posterior cruciate substituting femoral prosthesis ( pfc sigma , depuy , johnson and johnson ) with all - poly tibial component [ figure 5 ] was done . bone wax was used to control bony bleeding from metaphyseal lesions at the femoral cuts . closure was done under re - inflated tourniquet as there was generalized ooze but no active bleeding . infusion , first dose 30 min before tourniquet inflation , second dose 3 h later , and additional third dose 6 h after second dose ) . postoperative radiographs anteroposterior ( a ) and lateral ( b ) views showing good alignment . all - poly tibial component was used postoperatively , her hemoglobin dropped from 12.5 g% to 8.6 g% and she was transfused three units of packed cell volume . postoperative drain was kept for 48 h. the total collection in drain was 650 ml . prophylactically oral rivoroxaban 10 mg ( xeralto - bayer zydus pharma ) was given 2 weeks postsurgery , because such patients have increased risk of thromboembolism.34 subsequently , she was kept on oral aspirin 75 mg daily for a period of 4 weeks . she was given dvt above knee stocking and encouraged to do active ankle - foot exercises . aggressive mobilization was used under supervision of a physiotherapist . continuous passive motion and full weight bearing walking with a walker she was walking with walker support and had 090 rom by 7 day , when she was discharged . her wound healed well , and sutures were removed on the 15 day postsurgery . at 1-year followup , her knee society pain score improved to 97 and functional score improved to 100 . histopathological examination of the removed bone and synovial tissue showed vascular proliferation with lymphoplasmacytic exudates . conglomerate of vessels with thick walls and red blood cells in slit like lumina with hemosiderophages were seen . klippel  trenaunay syndrome is a type of arterio - venous malformation with three features : cutaneous hemangiomas , limb hypertrophy and varicose veins . vascular malformations are polysystemic in nature.9 our patient had all of the above except limb hypertrophy , so we can call it as a variant of klippel  trenaunay syndrome . unilateral knee arthritis on the side of vascular malformations probably happened due to recurrent chronic bleeds in her knee from synovial hemangiomas . the radiological squaring of femoral condyles and histologic presence of hemosiderophages made it to look like hemophilic arthritis ( although her coagulation profile was normal ) . after the tka , there is still future risk of recurrent bleeds in her left knee due to persistent hemangiomas in the synovium increasing the risk of infection ( as it is observed in hemophilic knees undergoing tka).10 challenges during surgery include identifying the extent of vascular anomaly and avoiding vascular injury resulting into uncontrolled bleeding . the presence of intra - medullary large lesion in this case precluded the use of intramedullary instrumentation . the only two cases of kippel  trenauney syndrome reported in literature , where knee arthroplasty had been performed , did not have intramedullary and intraosseous vascular malformation . the presence of intra - osseous vascular malformation makes the treatment by arthroplasty more difficult as we need to plan to avoid them during our bone cuts . recent reports show that there is no significant difference between an all - poly and metal backed tibial component in terms of survival and function.1112 the risk of back wear and osteolysis is reduced in all - poly tibia and the revision is easier.13 keeping all these in mind , an all - poly tibial component was used in this patient . we would like to suggest the following while performing knee arthroplasty in the patient with vascular malformation . first , proper vascular studies are essential to assess the intraosseous and deep extent of vascular malformation . third , navigated tka surgery may be helpful to avoid opening intramedullary space and intraosseous lesions . fourth , tranexamic acid should be used peri operatively to reduce intra operative blood loss , along with adequate anticoagulation prophylaxis to prevent dvt . special attention to asepsis must be paid as these patients are probably more prone to infection . the patient should be explained regarding guarded long term prognosis as the medical condition is un predictable in its progression . to conclude , tka in the presence of vascular malformations provides good functional score and better quality life in young patients when done with certain precautionary measures .
in klippel  trenaunay syndrome , vascular malformations are not only in skin and superficial soft tissues but also in deep tissues like muscles bones and joints . 
 it is well documemted that these recurrent intraarticular bleeds can cause early arthritis and joint pain . 
 performing arthroplasty in such patients is difficult and fraught with complications . 
 we describe such a case where navigated total knee arthroplasty was performed with success to avoid the problems of intra medullary alignment used in the presence of intra medullary vascular malformations . 
 we also suggest certain measures when knee arthroplasty is considered in such patients .