Is Dissection and Preservation of Adherent Popliteal Vessels From a Posterior Soft Tissue Mass Associated With a Higher Proportion of Local Recurrence in Patients With a Distal Femoral Osteosarcoma?

BACKGROUND: In patients who have osteosarcoma of the distal femur, there is concern that when dissecting the popliteal vessels from the posterior soft tissue extent of the tumor, a less-than-wide margin of resection may be achieved depending on the extent of the posterior soft tissue mass. Surgeons have little information to guide them when deciding whether dissecting the popliteal vessels in a patient in whom the vessels are in direct contact with a posterior mass will result in an increased likelihood of local recurrence compared with patients in whom the popliteal vessels are not in contact with the tumor mass.

QUESTIONS/PURPOSES: (1) Is dissecting the adherent popliteal artery and vein away from the posterior soft tissue extent of a distal femoral osteosarcoma by stripping them from their adventitia associated with an increased risk of local recurrence compared with patients in whom there is normal tissue between the tumor and vessels? (2) Is there an association with the type of tumor resection and the development of chest metastases and overall survivorship in this anatomic location?

METHODS: We retrospectively studied our patient database. From August 1, 1994, until December 31, 2019, all patients with conventional distal femoral osteosarcomas treated with chemotherapy and surgery were identified. A minimum of 2 years of follow-up was required for patients who were alive. A total of 545 patients matched these criteria. We excluded 7% (37 patients) who did not have a posterior soft tissue mass, 9% (51 patients) who has metastases, 0.7% (four patients) who had osteosarcomas in multiple sites, 1% (five patients) who died of chemotherapy complications, and 6% (30 patients) who were lost to follow-up. A total of 418 patients (211 men and 207 women) were eligible for this study. The mean age of the patients was 17 ± 6.6 years. All patients underwent routine staging (plain radiographs, MRI, chest CT, and bone scan) and received preoperative chemotherapy. The patients were divided into two groups according to the relationship between the popliteal vessels and the posterior extent of the extraosseous tumor. Axial MRI slices (T1, T1 with contrast, T2, and short tau inversion recovery) were analyzed separately by the two senior authors. Disputes were settled by a senior musculoskeletal radiologist and confirmed by the patient's operative report. In Group 1, which included 229 patients, there was a clear plane between the popliteal vessels and tumor. All patients underwent limb salvage. In Group 2, which had 189 patients, the popliteal vessels adhered to the tumor. This group was further subdivided into Groups 2a (patients in whom the vessels were dissected and limb salvage was performed; dissection of the popliteal vessels from the tumor entailed stripping the vessels from its adventitia in some areas) and 2b (patients in whom no attempt was made to dissect the vessels, and amputation or rotationplasty was performed). When rotationplasty was performed, the vessels were resected and reanastomosed. The decision to perform limb salvage in Group 1 was not debatable; however, in patients in Group 2, who had adherent vessels, the decision was made by the tumor board. Tumors with complete encasement of the vessels or nerves, nonunited pathologic fractures, and fungating of the tumor through the skin were treated by amputation or rotationplasty. Patients with tumors with adherent vessels that were not encased were offered limb salvage. This was often a shared decision with the patient. We performed a pathologic evaluation of the resected specimens to evaluate margins and tumor necrosis in all specimens.

RESULTS: Local recurrence-free survivorship was worse in patients with adherent tumors who underwent dissection of the vessels by stripping them from their adventitia (Group 2a; 68% at 5 years [95% CI 57% to 78%]) than in those without adherent tumors (Group 1: 96% [95% CI 93% to 99%]) and patients with adherent tumors who had amputation or rotationplasty (Group 2b: 99% [95% CI 96 to 100]; p < 0.01). Chest metastases developed in 142 patients. The proportion of chest metastases was higher in Group 2a (59% [60 of 101]) than in Group 1 (24% [55 of 229]) and Group 2b (31% [27 of 88]; p < 0.01). Five-year overall survivorship was worse in patients with adherent tumors who underwent dissection of the vessels by stripping them from their adventitia (Group 2a: 51% at 5 years [95% CI 40% to 63%]) than in those without adherent tumors (Group 1: 78% [95% CI 72% to 84%]) and patients with adherent tumors who had amputation or rotationplasty (Group 2b: 71% [95% CI 60% to 82%]; p < 0.01).

CONCLUSION: In light of these findings, when performing limb salvage for distal femoral osteosarcoma with adherent vessels, leaving an adventitial margin is associated with an increase in the incidence of local recurrence and poorer overall survivorship. Surgeons should refrain from dissecting these adherent vessels or at minimum discuss the expected outcomes with the patient. Future studies could target the outcome of vascular resection and bypass graft in the management of osteosarcoma.

LEVEL OF EVIDENCE: Level III, therapeutic study.