Enrico Martin

257 Morbidity and function loss after resection of MPNST thoracic, abdominal, and retroperitoneal sites), and unknown tumor site. Tumor size was categorized into <5cm, 5-10cm, and ≥10cm. Tumors originating from below the deep fascia were categorized as deep-seated. Whenever the nerve of origin was known it was categorized into motor, sensory, or mixed nerves. These were all considered major nerves. Surgical margins were defined as tumor-free (R0), microscopically positive (R1), and macroscopically positive (R2). Postoperative function loss was deducted from both clinical notes as well as surgical and pathological reports clarifying if nerves were completely excised. Motor deficits were graded according to the Medical Research Council muscle scale from M0 to M5. Sensory deficits were defined as any sensory deficit. Critical sensation was defined as partial or complete sensory loss of hand, plantar foot, or buttocks. Only motor and sensory deficits directly related to the MPNST and its resection were included. Sites of amputation were recoded into forequarter, above elbow, below elbow, hand, and finger for the upper extremities, and into hemipelvectomy, above knee, below knee, foot, and toe for the lower extremities. Functional reconstructions were defined as reconstructions aimed at restoring function of resected structures and may include: free functioning muscle transfers (FFMT), tendon reconstruction using transfers or grafts, or any nerve reconstruction using either grafts or transfers. Pedicled muscle transfers as a functional reconstruction were seen as tendon transfers. Outcomes and statistical analysis Qualitative assessment was performed for the presence and persistence of preoperative motor and sensory deficits, newly formed motor and sensory deficits, and outcomes of functional reconstructions. Baseline and treatment differences were assessed between patients with and without less than M3 postoperative motor deficits and between patients with and without critical sensory deficits using χ 2 -tests for categorical variables. Cases with unknown deficits were excluded from these comparisons. P-values <0.05 were considered statistically significant. Statistical analyses and data visualization were conducted using R version 4.0.0 (R Core Team, 2020). 11