Proximal Resection of the Fibula in the Treatment of Proximal Fibular Proximal Resection of the Fibula in the Treatment of Proximal Fibular

Chondrosarcoma includes several anatomoclinical forms of tumors with cartilaginous histogenesis. It is a malignant tumor whose tumor cells are associated with a cartilage matrix. Case report : we present the case of a patient with stage 1 chondrosarcoma of the proximal part of the left fibula. The patient underwent a proximal fibula resection with a favorable outcome. Conclusion: resection of tumors of the proximal fibula may cause knee instability, peroneal palsy through involvement of the external popliteal sciatic nerve or with local radiotherapy, a higher risk of delayed healing and the occurrence of fracture. Despite the risks of resection of the proximal fibula, good functional results can be obtained.


INTRODUCTION
Primary or metastatic fibular bone tumors are rare.For fibular localizations, we have only 2% of primary osteosarcomas [1] and 8% of primary Ewing's sarcoma [2].Chondrosarcoma is often primary, but in 10% of cases, it can occur on pre-existing benign tumors, mainly osteogenic exostoses and chondromas.The close relationship of the common peroneal nerve, the anterior tibial artery, and the lateral collateral ligament to the proximal fibula are major challenges in the surgical resection of proximal fibula tumors.For carcinologic resection of malignant bone tumors, the common peroneal nerve or peroneal muscle must sometimes be resected, which leads to a foot drop or sensory deficit [3].In carcinological resection, the proximal tibio-fibular ligaments and lateral ligaments of the knee can be sacrificed, which are often unavoidable.The loss of the lateral external ligament of the knee leads to instability of the lateral compartment of the knee.[4] Local radiotherapy increases the risk of tibial fracture.[5] As the number of fibula bone sarcomas is limited, there have been only a few reports on the outcome of treatment.

CASE REPORT
We report a case of a 50-year-old patient who has had pain in her left knee for 3 years.Clinical examination found pain on palpation of the outside of the left knee, no palpable mass was found.Standard radiographs of the left knee show a lesional process of the upper extremity of the left fibula with intraosseous micro calcifications.Figure 1 MRI of the left knee and the left fibula shows a lesional process of the upper metaphysis of the fibula with thinning of the cortex without obvious rupture of the upper pole and the lower pole are sharp and regular, this process measures 15 by 15mm extends in height to 53mm, with respect of the femoro-tibial joint.Figure 2 The extension report is normal.A surgical biopsy made shows grade 1 chondrosarcoma on an anapathological examination.The oncology RCP meeting decided on surgical resection.An external approach in front of the fibular head with resection of the path of the biopsy, then identification of the common peroneal nerve and the superficial and deep peroneal nerve with protection on silicone lakes.Figure 3 Fluoroscopic localization of the fibular tumor with en bloc resection of the upper end of the fibula 2 cm upwards from the tumor, maintaining the fibular head which has been fixed with the tibia by a 55 mm screw to preserve the ligament lateral lateral left knee and insertion of the biceps femoris.Figure 4 The patient presented a feeling of postoperative instability of the left knee on the external side which motivates a knee brace for a month.Immediate postoperative paresis of the common peroneal nerve which prompted a levator splint on the left forefoot.Full recovery of sensitivity and motor skills after one month.The fibular resection patch measuring 9x2x1.3cm with healthy lateral edges, and the tumor is confined to bone without soft tissue infiltration, and pathological examination reconfirmed the diagnosis of stage 1 chondrosarcoma.Figure 5 The patient recovered normal walking with the help of a cane after two months and walking without a cane after 3 months.The testing of the left knee in valgus varus is very satisfactory with a clear improvement in the functional score between the check-ups.The functional assessment was performed without a splint and without crutches during the most recent clinical follow-up.Clinical radio monitoring every 3 months for one year then every 6 months.

DISCUSSION
To ensure local control of bone tumors, a large resection is required [6], which will be based on a preoperative MRI and which will be an essential step in the planning and evaluation of the resectability of the tumor.The relationship between adjacent neurovascular structures and the tibia bone is particularly important.In order to preserve the lateral ligament complex for malignant tumors there must be a proximal area of more than 3-4 cm of healthy bone.If there is less than 3-4 cm of healthy bone an intra-articular resection of the proximal fibula with the lateral ligament complex should be done.If the tumor infiltrates the head of the proximal fibula, extra-articular resection of the proximal tibiofibular joint is inevitable.Gait abnormalities and knee instability occur after proximal fibula resection [7].Cadaver studies have shown that the collateral fibular ligament provides the main resistance to varus rotation in the knee [8].Knee instability can cause early osteoarthritis.[9]  Therefore, the collateral lateral ligament and the biceps tendon must be properly reattached to the tibia.If the biceps tendon is insufficient or left ligament, reconstruction using the fascia lata should be performed.
[7] Resection of the peroneal nerve causes serious problems such as paralysis of the common peroneal nerve with steppage, foot drop [10].This is why it should be kept if possible.However, if a large tumor resection does not allow the preservation of the common peroneal nerve, the patient must be advised and have the agreement and consent of the sensitivomotor sequelae due to postoperative paralysis.Hence the interest of preoperative planning based on MRI data.In case of infiltration of the common peroneal nerve, resection of this nerve is inevitable.[11] If the tumor only contacts the peroneal nerve superficially, an epineurectomy is an acceptable procedure for wide resection.Due to the resulting foot drop, patients require a levator foot orthosis for 90 ° ankle stabilization.Common peroneal nerve graft repair can be done at the same time or a year after the initial surgery without any improvement in foot extension.A good alternative to a nerve transplant could be a transfer of the posterior tibialis tendon to have the extension of the foot.[12] Sometimes there is delayed wound healing in patients who receive chemotherapy and radiotherapy after the operation.[13] CONCLUSION Resection of tumors of the proximal fibula can cause knee instability, fibular nerve palsy.With local radiotherapy, a higher risk of delayed healing and fracture.In the event of external popliteal sciatic nerve paralysis, a levator foot splint is well tolerated, with the possibility of nerve grafting immediately or after ensuring total control of recovery after radiotherapy.Despite the risk of proximal fibula resection good functional results can be achieved.

Figure 1 .
Figure 1.Standard AP and lateral X-ray with a lesional process of the upper extremity of the left fibula.

Figure 2 .
Figure 2. MRI of the left knee and the left fibula shows a lesional process of the upper metaphysis of the fibula with thinning of the cortex.

Figure 3 .
Figure 3. External surgical approach facing the fibular head with resection of the biopsy path, then identification of the common peroneal nerve and the superficial and deep peroneal nerve with protection on silicone lakes.

Figure 4 .
Figure 4. Frontal and lateral control radiograph showing the fibular head fixed with the tibia by a 55 mm screw to preserve the left lateral lateral ligament of the knee and insertion of the biceps femoris.

Figure 5 .
Figure 5.The fibula resection patch measures 9x2x1.3cm with healthy lateral edges, taking the path of the biopsy with the skin corresponding to the path.