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from march 2008 to december 2011 , three patients with a mean age of 27.7 years ( range , 22 to 38 years ) were treated for secondary chondrosarcoma from an osteochondroma of the proximal tibia involving the fibula at seoul national university bundang hospital .
one patient presented with a 6-month growing mass with a positive tinel 's sign over the fibular neck .
all patients had been informed of the existence of an osteochondroma at another clinic before the index visit .
radiologic studies showed definite changes in shape and size of the lesion compared with previous examination .
our radiological criteria for malignant transformation of an osteochondroma were as follows : ( 1 ) a growing lesion on serial radiographs taken after skeletal maturity ; ( 2 ) a lesion with cartilage cap thickness greater than 13 cm on magnetic resonance imaging ( mri ) scans ; and ( 3 ) a lesion with scattered punctuated calcification .
in all 3 cases , surgery was performed in three major steps : ( 1 ) isolation of the peroneal nerve ; ( 2 ) en bloc resection of the lesion including the fibula and lateral cortex of the proximal tibia preserving the fibula head ; and ( 3 ) arthrodesis of the proximal tibiofibular joint ( fig .
a skin incision was made along the peroneal nerve beginning posteriorly just proximal to the fibular head and terminating 23 cm distal to the tumor .
after identification of the common peroneal nerve under the peroneus longus , the tunnel of peroneus longus and extensor digitorum longus was unroofed .
after isolation of the deep peroneal nerve and the anterior tibial artery , the articular branch of the deep peroneal nerve and the recurrent tibial artery were ligated .
posteriorly , the peroneal origin of the soleus and the tibialis posterior was detached . under fluoroscopic guidance , the proximal and distal osteotomies preserving the fibular head were performed .
the lateral cortex of the proximal tibia from which the tumor originated was resected en bloc .
the proximal tibiofibular arthrodesis was carried out by fixation with a cannulated screw after removal of articular cartilage .
pathology of the resected specimen confirmed a grade 1 secondary chondrosarcoma in all patients . in the immediate postoperative period ,
active range - of - motion exercise was begun after subsiding of operative pain and full weighted - bearing in a knee brace was allowed to prevent a varus injury .
patients were observed in the clinic every 3 months for 2 years , every 6 months for the next 2 years , and annually thereafter .
mri of the primary tumor site was performed every 6 months for 2 years , and annually thereafter . at each clinic visit ,
a history was taken and a chest imaging was performed . at postoperative 1 year , the cannulated screw for arthrodesis of the proximal tibiofibular joint was removed after radiological confirmation of fusion .
functional evaluation was performed with the use of the functional classification system of the musculoskeletal tumor society ( msts ) , which includes 6 parameters , such as pain , function , emotional acceptance , use of walking supports , walking ability , and gait .
each was scored from 0 to 5 , with a maximum score of 30.7 ) at each visit , physical examination of knee joint stability and functional evaluation of the peroneal nerve were performed .
this study was performed under the approval of seoul national university bundang hospital institutional review board ( no .
pathologic findings were consistent with grade-1 chondrosarcoma with cartilage caps thicker than 1 cm in all 3 patients .
the cartilage component had smaller cells that lack matrix formation with increased cellularity and invaded the bone component .
there was no immediate postoperative complication including wound infection , nerve palsy , and vascular compromise .
there was no evidence of disease recurrence on the regional and chest images until the last follow - up .
serial radiological studies showed successful fusion in the proximal tibiofibular joint in all patients at a mean of 9.3 months after surgery ( range , 8 to 10 months ) ( fig .
there were no neurological deficits of the peroneal nerve until the last follow - up .
in all 3 cases , surgery was performed in three major steps : ( 1 ) isolation of the peroneal nerve ; ( 2 ) en bloc resection of the lesion including the fibula and lateral cortex of the proximal tibia preserving the fibula head ; and ( 3 ) arthrodesis of the proximal tibiofibular joint ( fig .
a skin incision was made along the peroneal nerve beginning posteriorly just proximal to the fibular head and terminating 23 cm distal to the tumor .
after identification of the common peroneal nerve under the peroneus longus , the tunnel of peroneus longus and extensor digitorum longus was unroofed .
after isolation of the deep peroneal nerve and the anterior tibial artery , the articular branch of the deep peroneal nerve and the recurrent tibial artery were ligated .
posteriorly , the peroneal origin of the soleus and the tibialis posterior was detached . under fluoroscopic guidance , the proximal and distal osteotomies preserving the fibular head were performed .
the lateral cortex of the proximal tibia from which the tumor originated was resected en bloc .
the proximal tibiofibular arthrodesis was carried out by fixation with a cannulated screw after removal of articular cartilage .
in the immediate postoperative period , active range - of - motion exercise was begun after subsiding of operative pain and full weighted - bearing in a knee brace was allowed to prevent a varus injury .
patients were observed in the clinic every 3 months for 2 years , every 6 months for the next 2 years , and annually thereafter .
mri of the primary tumor site was performed every 6 months for 2 years , and annually thereafter . at each clinic visit ,
a history was taken and a chest imaging was performed . at postoperative 1 year , the cannulated screw for arthrodesis of the proximal tibiofibular joint was removed after radiological confirmation of fusion .
functional evaluation was performed with the use of the functional classification system of the musculoskeletal tumor society ( msts ) , which includes 6 parameters , such as pain , function , emotional acceptance , use of walking supports , walking ability , and gait .
each was scored from 0 to 5 , with a maximum score of 30.7 ) at each visit , physical examination of knee joint stability and functional evaluation of the peroneal nerve were performed .
this study was performed under the approval of seoul national university bundang hospital institutional review board ( no . b-1503/292 - 109 ) .
pathologic findings were consistent with grade-1 chondrosarcoma with cartilage caps thicker than 1 cm in all 3 patients .
the cartilage component had smaller cells that lack matrix formation with increased cellularity and invaded the bone component .
there was no immediate postoperative complication including wound infection , nerve palsy , and vascular compromise .
there was no evidence of disease recurrence on the regional and chest images until the last follow - up .
serial radiological studies showed successful fusion in the proximal tibiofibular joint in all patients at a mean of 9.3 months after surgery ( range , 8 to 10 months ) ( fig .
there were no neurological deficits of the peroneal nerve until the last follow - up .
in this report , we described our surgical procedure and its outcomes for secondary chondrosarcoma arising from an osteochondroma of the lateral side of the proximal tibia involving the proximal fibula .
the procedure can be summed up as resection of the tumor including the fibula , preservation of the peroneal nerve and the fibular head , and arthrodesis of the proximal tibiofibular joint . considering that malignant transformation of osteochondroma reveals a low - grade chondrosarcoma in most patients , we believe there is sufficient justification for preservation of the functional structures in the procedure .
authors have reported that the incidence is 0.4%2% in patients with solitary osteochondroma and 5%25% in patients with hereditary multiple exostoses.689 ) fortunately , most chondrosarcomas arising in an osteochondroma have proved to be low - grade . in a study by ahmed et al,10 ) among 107 secondary chondrosarcomas arising in osteochondrosarcoma , 97 tumors were grade 1 , and 10 tumors were grade 2 .
, secondary chondrosarcoma tends to occur most commonly in the pelvis , trunk , and the proximal femur.91011 ) affection of the proximal tibia and its outcomes has been rarely reported , although some large series study included a few cases.12 ) surgical resection of a malignant bone lesion of the medial condyle of the proximal tibia is considered as relatively easy .
however , a wide resection in the lateral side of the proximal tibia may cause permanent functional impairment , which is associated with sacrifice of the peroneal nerve and the proximal fibula . with respect to the fibular resection , malawer13 ) described two detailed resection types in 1984 .
type i or marginal resection requires excision of the proximal fibula with 23 cm of the diaphysis and muscle cuff in all directions with preservation of the common peroneal nerve .
type ii or wide extra - compartmental resection involves resection of 6 cm of normal diaphysis , the anterior and lateral muscle compartments , the peroneal nerve , the anterior tibial artery and the tibiofibular joint extra - articularly .
marginal or intralesional margin resection in malignant bone tumor usually results in poor oncological outcomes .
however , some authors advocated intentional marginal resection around structures that are important for limb function .
kanazawa et al.14 ) reported the outcomes of intentional marginal excision of osteosarcoma of the proximal fibular to preserve limb function .
when a good response to preoperative chemotherapy was expected based on radiologic studies , they preserved the peroneal nerve and the anterior tibial vessels in 3 patients with osteosarcoma in the proximal fibula . with a minimum 5-year follow - up ,
all 3 patients had normal ankle and knee functions without evidence of local recurrence . considering that the majority of secondary chondrosarcomas from osteochondromas turn out low - grade neoplasms , preservation of functional structures can be regarded as a reasonable approach .
erler et al.15 ) added two more resection types ( type iii and iv ) , both of which were based on malawer 's type i resection : type iii resection involves the sacrifice of the deep peroneal nerve and type iv resection preserves the proximal tibiofibular joint .
any systematic study has not evaluated the role of arthrodesis of the proximal tibiofibular joint in knee stability and functional outcomes after resection of the proximal fibula .
most studies , in which type iv resection was included , reported that the arthrodesis of the proximal tibiofibular joint is not essential.16 ) einoder and choong17 ) also noted that wide resection of the fibular head for a tumor might not require reconstruction , unlike treatment of traumatic disruption of the lateral ligamentous structures of the knee .
they reported that function was satisfactory in 6 consecutive cases where resection of the fibular head was done without ligamentous reconstruction after 14 years of follow - up .
however , 3 of 6 patients in their series showed 1 + or 2 + lateral instability on physical examination
youdas et al.18 ) in their study on donor site morbidity after vascularized fibula transfer , suggested that inadequate fixation of the proximal segment would cause superior migration of the fibula and excessive coronal plane motion on the donor site compared with the normal control .
krieg et al.19 ) reported a case with osteochondroma of the fibula for which they performed a marginal resection by reflecting the fibular head proximally and an arthrodesis of the proximal tibiofibular joint . in the current study ,
all 3 patients returned to sports activities . moreover , one of them ( patient no .
the advantage of arthrodesis of the proximal tibiofibular joint after type iv fibular resection is that it provides lateral stability of the knee joint . in the normal knee ,
varus stress is restrained by the lateral ligament complex , and it is transferred to the fibular bony structure . without an arthrodesis of the proximal tibiofibular joint ,
varus stress after type iv resection is transferred to the tibia via the tibiofibular joint . in this situation ,
the varus stress is restrained by the joint capsule of the joint rather than the lateral ligament complex .
arthrodesis of the proximal tibiofibular joint could return the role of varus restraint to the lateral ligament complex ( fig .
we believe that the arthrodesis of the proximal tibiofibular joint after type iv fibular resection is worthy enough to compensate for the additional effort of arthrodesis and removal of the screw .
we think that our reconstruction method could be one of options for reconstruction after resection of the lateral part of the knee according to patients ' age and their demands . in conclusion
, for the secondary chondrosarcomas arising from an osteochondroma in the lateral side of the proximal tibia involving the fibula , we performed removal of the tumor including the proximal fibula while preserving the fibular head and the common peroneal nerve , followed by arthrodesis of the proximal tibiofibular joint .
all of the three patients had no evidence of disease and showed excellent functional outcomes until the last follow - up . in spite of the limitation of the small number of patients and lack of a comparison group
, we suggest that our procedure introduced in this article could provide satisfactory oncological and functional outcomes .
there are few reports on the surgical treatment of secondary malignancy arising from an osteochondroma on the lateral side of the proximal tibia . from march 2008 to december 2011 
 , 3 patients were treated for a secondary chondrosarcoma from an osteochondroma of the proximal tibia involving the fibula . 
 the operative procedure can be summed up as follows : ( 1 ) resection of the tumor including the fibula ; ( 2 ) preservation of the peroneal nerve and the fibular head ; and ( 3 ) arthrodesis of the proximal tibiofibular joint . 
 serial radiological studies showed successful fusion in the proximal tibiofibular joint in all patients . 
 the musculoskeletal tumor society functional scores were excellent in all 3 patients . 
 no patients showed instability of the ipsilateral knee joint in any direction . 
 all 3 patients could return to sports activities . until the last follow - up , there was no evidence of disease recurrence . 
 we suggest that the operative procedure described in this article would provide satisfactory oncological and functional outcomes .