OR10.1,OR11.1 | Bone Tumours and Peripheral Nerve Injuries — Graded Quiz

Correct. Stage IIB (high-grade extracompartmental) tumours require wide surgical margins — resection with a surrounding cuff of normal tissue — for limb salvage. Radical resection removes the whole compartment and is rarely needed when chemotherapy allows limb-salvage.

Enneking staging: Stage I = low grade, Stage II = high grade; A = intracompartmental, B = extracompartmental. Osteosarcoma is typically Stage IIB (high grade, extracompartmental). Curative surgery requires a wide margin (normal tissue cuff around the tumour). Marginal or intralesional excision leaves residual tumour and leads to recurrence.

Enneking Stage IIB (high-grade) requires a wide margin. Anything less (marginal or intralesional) leaves tumour behind.

Correct. Lung is the most frequent site of Ewing's sarcoma metastasis (~20% at presentation). Bone and bone marrow are the second most common sites.

Ewing's sarcoma metastasises most commonly to the lungs, followed by bone and bone marrow. Lung metastases are the most frequent finding and worsen prognosis significantly; whole-lung irradiation is used when lung metastases are present.

Ewing's sarcoma spreads haematogenously, and the lungs are the primary distant target (as with most sarcomas).

Correct. Grade III GCT (cortical breach, soft tissue extension) is best managed by en bloc excision and joint reconstruction (e.g., distal femoral replacement) given the high curettage recurrence rate at this grade.

Campanacci grade III GCT has breached the cortex with a soft tissue mass. Extended curettage + local adjuvant (phenol/liquid nitrogen/argon beam) ± bone cement is standard for grades I–II. Grade III with large soft tissue extension often requires en bloc wide excision and reconstruction (distal femoral replacement prosthesis), because curettage alone has an unacceptable recurrence rate.

Grade III GCT with cortical breakthrough and soft tissue extension requires en bloc excision; curettage has too high a recurrence rate at this stage.

Correct. High Mirel's score + pathological fracture in the subtrochanteric region requires stabilisation with a long IM nail (to protect the whole femur) followed by radiotherapy to treat the metastasis.

Mirel's scoring (site, pain, nature of lesion, size) with a score ≥9 indicates high fracture risk and prophylactic or therapeutic fixation is recommended. Subtrochanteric pathological fractures through metastases are best managed with an intramedullary nail (typically long cephallomedullary nail) covering the whole femur, followed by radiotherapy. Open reduction with plate is mechanically inferior at this site.

Mirel's ≥9 and an actual fracture mandate operative fixation (IM nail for subtrochanteric/diaphyseal femur) + adjuvant radiotherapy.

Correct. The biopsy must be positioned longitudinally in line with the definitive incision so the contaminated tract is excised with the tumour en bloc — a fundamental principle of musculoskeletal oncology.

The biopsy incision must be longitudinal and placed in the exact line of the planned definitive resection (anterolateral thigh approach), so the biopsy tract is excised en bloc with the specimen. Placing the biopsy medially or posteriorly would contaminate a different compartment and necessitate a wider (potentially limb-sacrificing) resection.

Biopsy placement must match the planned resection approach — a misplaced biopsy can contaminate additional compartments and eliminate limb salvage.

Correct. Sciatic nerve injury is the classic nerve complication of posterior hip dislocation. Combined foot drop AND knee flexion weakness indicates sciatic nerve palsy, not an isolated peroneal nerve injury.

Posterior hip dislocation injures the sciatic nerve in up to 10–20% of cases. The peroneal division of the sciatic nerve is more vulnerable (foot drop, dorsal foot sensory loss), but involvement of the tibial division (knee flexion weakness) indicates a higher sciatic nerve lesion rather than a purely common peroneal injury at the fibular neck.

Posterior hip dislocation + foot drop + knee flexion weakness = sciatic nerve injury. The combination of peroneal and tibial components localises the lesion to the sciatic nerve at the hip.

Correct. Median nerve injury at the wrist causes ape thumb deformity (thenar wasting, loss of opposition/abduction of thumb) and sensory loss over the lateral 3.5 digits and palm.

At the wrist, the median nerve supplies the thenar muscles (abductor pollicis brevis, opponens pollicis, flexor pollicis brevis superficial head) and first two lumbricals. Injury causes ape thumb deformity (thenar wasting + loss of opposition), and sensory loss over the lateral 3.5 digits. Wrist flexion is intact (FCR and FDS arise in the forearm). Clawing of index and middle fingers (from lumbrical loss) is subtler than ulnar claw.

Median nerve at the wrist → thenar muscles + lateral 3.5 digits. Ring/little clawing = ulnar nerve; wrist drop = radial nerve.

Correct. Axonotmesis: the axon degenerates distal to the injury (Wallerian degeneration) but the endoneurial sheath guides regeneration at ~1 mm/day. Full spontaneous recovery is expected without surgery, though the timeline can be months.

In axonotmesis, the axon is disrupted but the endoneurial tubes are intact, guiding regenerating axons. The nerve regenerates at approximately 1 mm per day (1 inch per month). Clinical implication: spontaneous recovery is expected; calculate recovery time by dividing the distance from injury to end organ by 1 mm/day. In contrast, neurotmesis (Seddon Grade III) requires surgical repair because endoneurial tubes are disrupted.

Axonotmesis = disrupted axon but intact endoneurium → guided spontaneous regeneration at 1 mm/day. Surgery is not required (unlike neurotmesis).

Correct. Fibrous dysplasia is benign. When symptomatic or at fracture risk, curettage and bone grafting (cortical grafts preferred, as cancellous graft is often resorbed) with internal fixation as needed is the surgical standard.

Fibrous dysplasia is a benign developmental lesion where normal bone is replaced by fibrous tissue with woven bone (ground-glass X-ray appearance). Management is conservative if asymptomatic. When it causes pain, deformity, or is at fracture risk, surgical treatment (curettage + bone grafting or intramedullary stabilisation) is indicated. Unlike malignant tumours, it does not require wide excision.

Fibrous dysplasia is a benign lesion; it does not require the oncological margins or chemotherapy used for malignant tumours.

Correct. Total brachial plexus avulsion involves C5–T1 roots and includes Horner's syndrome (T1 sympathetic root avulsion). The entire upper limb is flail and insensate; nerve transfer (e.g., intercostal nerves) is the only reconstructive option.

Horner's syndrome (ptosis, miosis, anhidrosis) indicates injury to the T1 root preganglionic sympathetic fibres — signifying a root avulsion at C8-T1 level. Combined with paralysis of the entire upper limb from C5, this represents a total brachial plexus avulsion (C5–T1). Avulsion injuries are preganglionic and cannot be repaired by direct suture; nerve transfer is the only option.

Horner's syndrome + complete upper limb paralysis = total brachial plexus avulsion (C5–T1 root level). Neither Erb's nor Klumpke's alone explains this picture.