Lower Extremity Tumours 

The distal femur and proximal tibia are the most common site for osteosarcoma, GCT, ABC and malignant fibrous histiocytomas. The quadriceps is the most common compartment for soft tissue sarcomas. 

PELVIS

Most common site for round cell sarcomas and osteosarcomas

Marrow tumors are common as the pelvis contains active marrow. (lymphomas, myeloma and Ewing’s).

Due to the thin cortex, a large extraosseous component is frequent.

Dull pain, fullness, sciatica, hip pain and bladder and bowel symptoms can be the presentation.

The main functional regions exist for management; the ilium, the sacral area (nerves), the rami and the periacetabular (hip joint) regions. 

X-rays can be very inaccurate in diagnosis here, thus CT scans and MRI scans are utilized. IVP and angiograms may be needed prior to surgery.

Biopsy

Be aware of incisions used for hemipelvectomy

For the iliac wing, make the incision parallel to the crest

The acetabulum should usually be approached anteriorly between sartorius and tensor fascia. 

Avoid the posterior (gluteal area).

II or CT guided core biopsies are usually used.

Specific tumors

Chondrosarcoma 1/3^rd of these arise in the pelvis. Usually present large, but are low grade. The jelly-like substance they contain can easily contaminate the wound. Limb sparing resection is the main treatment, although large tumors will need hemipelvectomy. 

Osteosarcoma Has a poorer prognosis than in the periphery. Requires hemipelvectomy to get safe margins. May involve the sacrum which may need to be removed. Invasion into the pelvic veins makes surgery difficult. Chemotherapy may be used to reduce tumor mass. 

Ewing’s sarcoma 2^nd most common site. Presents as a lytic lesion with a huge extraosseous component. High dose radiotherapy in combination with chemotherapy improves local control and treats systemic disease. After induction (neoadjuvant) chemotherapy, resection may be attempted with limb sparing procedures. 

Metastatic carcinoma common in the pelvis and periacetabular region. May have large extraosseous component, often bleed significantly, thus embolization can be used. In the femoral head and acetabulum, THR with cemented cup and stems can be used.

Surgical options

Hemipelvectomy is an amputation through the SIJ and symphysis pubis (hindquarter amputation). The dissection is retroperitoneal, with ligation of the common iliac artery, vein and psoas at the upper level of the SIJ. Only the peritoneum, ureter, bladder and some pelvic floor muscles remain. A large subcutaneous gluteal flap is used for closure. An alternative technique using a quadriceps myocutaneous flap for closure has been described for lesions involving the buttock soft tissues. 

Internal hemipelvectomy is used when the pelvic tumour can be resected, and the defect reconstructed with anatomic-specific allograft, custom implant, or occasionally with the resected pelvis reinserted after extracorporeal radiotherapy.

Limb sparing: The ilium, periacetabular and pubic rami may all individually be resected. SIJ, peritoneal and sacral involvement is a contraindication. No bony reconstruction is needed after removal of ilium or rami. Periacetabular resections can often left as a Girdlestone, or reconstructed with an arthroplasty or arthrodesis. 

PROXIMAL FEMUR

Metastatic is most common malignant lesion

In children, Ewing’s more common than osteosarcomas

Primary sarcoma is rare, with the commonest being chondrosarcoma.

Most common benign tumours are fibrous dysplasia, enchondromas and GCT’s.

Pain and pathological fracture are the usual presentation

Extraosseous extension occurs into the psoas and adductor muscles. Direct involvement of the femoral nerve, sciatic nerve and femoral artery is rare.

Acetabular and pelvic extension can occur.

Angiography may be useful in hypernephromas as embolization may be needed. A Watson-Jones approach is recommended for biopsy in proximal lesions, otherwise a lateral approach beneath the abductor insertion.

Specific tumors

UBC (unicameral bone cyst/simple bone cyst) 2^nd most common site, X-rays not as typically diagnostic. Percutaneous aspiration and prednisolone injection is recommended.

Chondroblastoma 3^rd most common site. Can arise either in the capital epiphysis or in the greater trochanter apophysis. Beware of clear cell chondrosarcoma mimicking this. Treatment involves curettage, cryotherapy and reconstruction of the defect. Care to avoid synovial contamination must occur. Head can be approached anteriorly or laterally. 

GCT and ABC Typically involve a large portion of the femoral neck and trochanter. Pre-operative embolization of feeder vessels may help prior to curettage. Cryosurgery and cement reconstruction is good for smaller lesions. Large tumors need endoprosthetic replacement.

Fibrous dysplasia: The aim is to prevent deformity and fracture. Curettage and reconstruction with fibular struts and plate and screw fixation may be needed. Medial struts help discourage Shepherd’s crook deformity.

Osteoid osteoma most common site. Can be intramedullary (little sclerosis), intracortical (classic) or subperiosteal (scooped-out defect). 

Ewing’s most common site. X-rays usually show classic onion-skin periosteal reaction. Treatment involves chemotherapy and surgery, +/- radiotherapy. Must prevent fracture during this process, as this will mean that hemipelvectomy or limb-sparing surgery is almost impossible, with high risk of local recurrence. 

Osteosarcoma only 4% in this area. Chemotherapy followed by amputation or resection is the treatment. Low grade or paraosteal variants can have endoprosthetic reconstruction. 

Chondrosarcoma 2^nd most common site. Lesions are larger, but usually low grade and can easily contaminate the wound. Limb sparing resection can often be used. 

Metastatic:  If fracture, needs surgery, otherwise may be treated with radiotherapy and protected weightbearing. A lesion >1/3^rd of diameter may need prophylactic fixation. Myeloma and breast secondaries tend to reossify after radiotherapy, whereas prostatic and colon usually do not. Cemented stems are usually used, need to bypass the lesion by at least 2 diameters, i.e long stems. 

Surgical procedures

Benign lesions need curettage with graft or cement to fill the void

Low grade (stage I) sarcomas may be treated by en bloc resection.

High grade (stage II) need wide resection of the hip and result in significant loss of the proximal femoral muscles. Endoprosthetic replacement or massive allograft is needed. 

Radiation may be needed, as local recurrence of stage II sarcomas here is about 20%

More extensive high-grade lesions need hemipelvectomy, as hip disarticulation does not remove all the contaminated tissue.

A modified hemipelvectomy can be performed through the sciatic notch and symphysis pubis. The gluteus maximus and portion of iliac wing are left. 

Proximal femoral resection. Most stage IA/B and stage IIA tumors can be resected. Sciatic nerve, femoral vessel, intrapelvic extension or acetabular involvement are contraindications. The abductors and iliopsoas are removed, and the trochanter preserved if possible. Success is best achieved if the abductors can be reattached. 

KNEE

Most common location for primary tumours

GCT’s, ABC’s, osteosarcomas and paraosteal osteosarcomas are common.

Pain is common with all, fracture with GCT’s.

In the distal femur, extraosseous extension displaces but usually not invading muscles

Popliteal neurovascular involvement can occur

Intraarticular extension can occur, usually along the cruciates or synovial attachment. An effusion should raise suspicion of this. 

Biopsy should occur in line with the universal knee incision. For the proximal fibular, a direct lateral approach is made.  Biopsy must be guided by the tumour surgeon.

Specific tumors

Osteoid osteoma in distal femur 3^rd most common site.

Non-ossifying fibroma rarely needs treatment

Giant cell tumour has a high recurrence after simple curettage. Adjuvant cryosurgery or other local adjuvant may be needed, followed by graft or cement reconstruction. If the joint surface is involved, then prosthesis or arthrodesis is needed. Multiple recurrences will need en bloc resection. 

Parosteal osteosarcoma characteristically located on the posterior femoral surface. Vascular structures are usually not involved. Biopsy should occur along the lateral intermuscular septum, guided by the tumour surgeon. Removal is needed with the cortex and/or capsule. Graft may be required or large prosthetic replacement.

Surgical management

Spindle cell tumors traditionally were treated with hip-disarticulation or AKA. Now limb-sparing techniques can be used. This is combined with chemotherapy and reconstruction with arthrodesis or endoprosthesis. (stage I and IIA/B). Amputation is reserved for those with neurovascular involvement, pathological fracture or multidirectional soft tissue extension. 

Limb sparing

Distal femur involves removal of distal 15-20cm of femur and proximal tibial articular surface. If significant quadriceps involvement, then fusion is better than arthroplasty. Endoprosthetic replacement allows early weightbearing. 

Proximal tibia more difficult for limb sparing, due to the restraints of soft tissue coverage and tendon attachments. If the proximal tibia is removed, the tibiofibular joint is also taken extraarticular. The medial gastrocnemius is transferred to the patellar tendon to allow soft tissue coverage of the area and improved results. 

Proximal fibula has the problem of early soft tissue invasion and proximity to the CPN (common peroneal nerve).  Resection involves wide excision of all adjacent muscle groups. The lateral ligament is reattached to the lateral joint capsule. May need staged tendon transfers to ankle/foot to deal with foot drop if nerve requires sacrifice.

LOWER LEG (TIBIA/FIBULA)

Primary sarcomas of the shaft tend to be round cell origin

Metastatic tumors are rare below the knee

Present as a vague ache, usually less advanced than the more proximal lesions

Small tumors of the fibula can be biopsied by excision of the lesion.

The tibia should usually be approached through its medial boarder.

All incisions should be longitudinal

Specific tumors

Adamantinoma usually in the tibial diaphysis, generally eccentric and anterior. Due to high local recurrence, en bloc excision is recommended. Some extraosseous involvement is common. The defect can be reconstructed with segmental fibular grafts with IM rod fixation.

Osteoid osteoma 2^nd most common site. Differential diagnosis is stress fracture. May arise from intramedullary or cortical location. Large defects in young patients may ossify without a graft, otherwise the fibula is often used. 

Metastatic carcinoma usually late in disease, can usually be treated with brace and radiotherapy. 

Surgical management

For defect reconstruction the fibula can be used as a graft

High grade spindle cell tumour may require an AKA (above knee amputation).

Round cell tumors need chemotherapy and radiotherapy

Fibular resection is approached between peroneus longus and Soleus. The peroneal artery and vein which travel along the medial boarder must be ligated. Excision to within 5-6cm of the lateral malleolus still leaves a stable ankle. Wide excision includes the proximal tibiofibular joint and the adjacent muscles. 

Limb sparing tibial excision. Excision from below the patella to above the ankle syndosmosis can be reconstructed with a vascularized fibular graft or prosthesis.

FOOT AND ANKLE

Tumors here are rare, and mostly benign

Soft tissue tumours also rare, include clear cell sarcoma of achilles tendon sheath, epitheloid and synovial carcinoma and PVNS.

Pathological fracture is unusual, usually an incidental finding

Lateral approaches for biopsies are used to avoid contamination of neurovascular structures

Specific tumors

UBC (unicameral bone cyst/simple bone cyst) occasionally occur in the distal tibia, rarely in the calcaneus. Diagnosis with aspiration of yellow fluid, and treatment involves injection with steroid.

Intraosseous ganglion Most common location is the distal tibia, usually the medial malleolus. Tarsal bones the 2^nd most common. Radiolucent defect with thin margin of sclerotic bone. Curettage with removal of lining is usually curative. If the defect is large, graft may be needed. 

GCT’s and ABC’s occasionally occur, usually in the distal tibia or tarsal bones. (esp. Talus for GCT). Lytic area seen on X-rays, increased uptake on bone scan. CT helps determine the amount of bone destruction. Surgery involves curettage, (occasionally cryosurgery) and grafting. 

Chondrosarcoma are rare, tend to be low grade. Local resection can usually obtain control. Cartilage tumors of the metatarsals and phalanges are usually benign enchondromas. 

Fibromatosis tend to be one of 4 types; superficial fibromatosis, infantile digital, infantile aggressive, and congenital fibrosarcoma. Plantar fibromatosis grows slowly, 25% bilateral, fasciectomy if symptoms. Infantile digital presents as small nodules along the toes, excision is curative. The aggressive form and fibrosarcomas require wide excision, amputation may be needed if recurrences. Post operative radiotherapy can help. Metastases are usually rare. 

PVNS presents as a juxtaarticular mass, mimicking sarcoma. Excision and synovectomy are needed, and radiotherapy may help. Arthrodesis may be needed with wide excision for recurrences. 

Surgical management

Curettage is the main treatment with grafting.

Recurrent or aggressive benign tumors may need cryotherapy or other adjuvant

Poor results with resection of the talus and calcaneus, if inadequate margins then amputation is better (BKA)

Metatarsals can be resected, but if margins are not clear then Symes amputation is usually used.