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uni - compartmental knee arthritis may be treated with several surgical options including uni - compartmental knee arthroplasty , total knee arthroplasty and high tibial osteotomy .
non - union is a well - established and common complication that may arise from the latter option and few reports have shown successful treatment of persistent non - union of high tibial osteotomy .
we present a case of persistent non - union after high tibial osteotomy treated with autologous iliac crest bone grafting and revision plating . at 1 year post - operative interval ,
in this patient with persistent non - union following high tibial osteotomy , the aim of revision was to restore alignment and effect bone healing while preserving adequate tibial bone stock .
revision plating with autologous bone grafting is a good surgical strategy in the treatment ofpersistent non - union with hardware failure .
uni - compartmental varus osteoarthritis in young and active patients has always proven to be a surgical challenge .
high tibial osteotomy has become a widely accepted extra - articular , biological option with high survival rates at 5 year and good functional outcomes .
the theoretical advantages of opening wedge high tibial osteotomy include greater precision in intraoperative angular correction , obviation of need for lateral dissection and fibular osteotomy with reduced risk of common peroneal nerve palsy , a less invasive surgical approach and absence of lateral knee instability . despite these advantages ,
several authors have reported complications associated with opening wedge high tibial osteotomies [ 2 - 8 ] , including infection , deep vein thrombosis , lateral tibial plateau fracture , common peroneal nerve palsy , non - union , delayed union , loss of correction and vascular injuries .
the incidence of non - union after hto has been reported to be as high as 5.7% [ 9 , 10 ] . in this report , we highlight the treatment of persistent non - union in a high tibial osteotomy case with the use of autologous bone grafting and revision plating .
a 53-year - old chinese lady , with a history of hypertension , diabetes mellitus and chronic depression , presented with an 8 month duration of severe medial right knee pain associated with varus knee deformity .
she was initially treated conservatively with a course of non - steroidal inflammatory drugs , intra - articular visco - supplementation , physiotherapy and weight loss regime . despite a two - year trial of non - surgical therapy
, she continued to experience a deterioration in her symptoms with limitation ofher functional status requiring a quadstick as a walking aid .
range of motion was limited to 0 to 110 with no fixed flexion deformity found bilaterally .
significantly , there was medial joint line tenderness and absence of lateral joint line and patellofemoral tenderness .
1 ) . significant medial compartment radiographic osteoarthritic changes were noted in the right knee , corresponding to kellgren - lawrence grade 3 osteoarthritis .
these changes included loss of medial joint space , varus knee deformity and the presence of marginal osteophytes .
the femoral - tibial angle measured was 175 and the anatomical lateral distal femoral angle was 86. we performed a diagnostic knee arthroscopy and then proceeded to an opening wedge high tibial osteotomy using the tomofix plate after a failed two year trial of conservative therapy ( fig .
arthroscopic findings include medial compartment outer bridge grade 4 lesion with degenerate radial tear of the posterior horn of the medial meniscus .
intra - operative correction with the opening wedge osteotomy was guided with the use of radiographic imaging .
post - operatively , she was started on a rehabilitation programme , progressing to partial weight bearing at about 6 weeks .
femoral - tibial angle measured was 175 and anatomical distal femoral angle was 86. post - operative radiographs .
however , she continued to experience pain over the osteotomy site up till 6 months post operatively .
however , her symptoms deteriorated and she developed a fix flexion deformity of her right knee .
a computed tomogram performed 8 month postoperatively revealed non - union of the osteotomy site with hardware failure and loss of correction ( fig .
the proximal tibia was angulated laterally in varus and anteriorly increasing the tibial plateau slope .
radiographs at 8 month post - operation showing nonunion radiographs at 8 month post - operation showing non - union the patient subsequently underwent revision plating with autologous bone graft .
a proximal tibial locking plate was placed on the posteromedial aspect and locking screws were used to secure the fixation .
post - operatively , the patient progressed from non - weight bearing to partial weight bearing at 3 months and full weight - bearing at 6 months post - operatively .
she no longer experienced pain at the osteotomy site and repeat radiographs performed at 1 year post - operatively showed union ( fig .
she was able to ambulate without any walking aids and no longer has any limitations in her daily activities .
non - union is an uncommon complication associated with opening wedge high tibial osteotomy [ 5 , 7 , 9 , 10 ] .
some authors have advocated non - operative treatment with a regimen of protected weight bearing to achieve union . in a study by martin
et al   looking at the adverse events following high tibial osteotomy , 3.2% ( 10/317 ) of cases were complicated by non - union ( defined as absence of radiographic non - union at 6 months ) and 1% of cases had hardware failure and loss of correction . in this retrospective review ,
nonoperative treatment with continued protected weight bearing regimen was able to achieve union in 7 out of 10 patients .
three patients underwent revision surgery for aseptic non - union with the use of either autologous iliac crest bone grafting or allograft .
all 3 patients had further supplementation either with bmp-2 , bmp-7 or platelet - rich plasma .
active smokers were found to have a higher rate of non - union ( 4.8% ) as compared to ex - smokers ( 4.3% ) and non - smokers ( 2.4% ) while diabetic patients were also found to have a higher rate of non - union ( 16.6% ) than non - diabetic patients ( 2.6% ) .
various surgical options have been utilized in the treatment non - union after high tibial osteotomy including internal fixation with bone grafting [ 10 , 12 ] , external fixation with grafting including the use of ilizarov external fixator [ 13 - 15 ] and staged total knee arthroplasty . in a high tibial osteotomy , the metaphyseal location of the non - union site makes the achievement of stable fixation difficult because of the transverse plane of the non - union and a small proximal fragment .
a major disadvantage of utilizing external fixation is the inability to provide adequate rotational stability as the small proximal fragment has little room for multiple steinman pin fixation .
furthermore , external fixation may introduce pin site infections , potentially converting an aseptic non - union to a septic non - union .
wolff et al in his series of 6 cases reported successful outcomes with the use of internal fixation and bone grafting .
internal fixation obviates the need for pin sites and reduces the risk of infection and chronic osteomyelitis . with the primary goal of effecting bone healing over the non - union site and preserving tibial bone stock for a subsequent total knee arthroplasty , internal fixation with bone grafting
our patient experienced persistent non - union despite conservative measures , thus , in our case the aim of the revision with internal fixation using a proximal locking plate was to restore alignment and effect bone healing .
revision plating with autologous bone grafting is a good surgical strategy in the treatment ofpersistent non - union with hardware failure .
with wide ranging considerations including achieving union and restoring alignment while preserving bone stock , revision plating with autologous bone grafting remains a key strategy in treating such cases .
introduction : uni - compartmental knee arthritis may be treated with several surgical options including uni - compartmental knee arthroplasty , total knee arthroplasty and high tibial osteotomy . 
 non - union is a well - established and common complication that may arise from the latter option and few reports have shown successful treatment of persistent non - union of high tibial osteotomy.case presentation : we present a case of persistent non - union after high tibial osteotomy treated with autologous iliac crest bone grafting and revision plating . at 1 year post - operative interval , 
 successful union was achieved after revision internal fixation . 
 in addition , a good functional outcome was achieved.conclusion:in this patient with persistent non - union following high tibial osteotomy , the aim of revision was to restore alignment and effect bone healing while preserving adequate tibial bone stock . 
 revision plating with autologous bone grafting is a good surgical strategy in the treatment ofpersistent non - union with hardware failure .