Skeletal muscle metastasis from the most common carcinomas orthopedic surgeons deal with. A systematic review of the literature

There is scarce information in the literature dealing with the clinical presentation, management and oncologic outcomes of skeletal muscle metastases (SMM). We sought to perform a systematic review of the literature to investigate: (1) tumor characteristics of SMM, (2) therapeutic approach, and (3) oncological outcomes. A systematic review of the literature was performed using PubMed and EMBASE search engines. A total of 3231 references were reviewed and 49 studies were included. Demographic data, presentation characteristics, and oncological outcomes were recorded. Statistical analysis was performed using SPSS 22.0 software (IBM; Armonk, New York) and Comprehensive Meta-Analysis software version 3 (Biostat, Inc.), with p < 0.05 as statistically significant. A total of 231 patients were included. These tumors presented more commonly on males 58.4% (135/231), with a mean age of 60.08 ± 10.6 years, and in the axial area 39.6% (88/222). The most common carcinoma type was lung 41.1% (95/231). Resection of a single metastases did not change survival significantly (p = 0.992). LRR was higher within the group of patients that underwent WLE compared with non-WLE [31.3% (23/74) vs. 8.7% (2/23), p ≤ 0.001]. Kaplan-Meier survival analysis for the entire cohort showed an estimate of 15.3 months [95% confidence interval (CI) 11.6-19; standard error (SE) 0.432], with lung carcinoma carrying the worst prognosis 6.7 months (95% CI 5.4-8.07; SE 0.68). Patients with a single SMM showed a worse estimate mean survival time compared to patients with multiple metastases limited to muscles [8.6 months (95% CI 4.7-12.5; SE 2.0) vs 25.4 months (95% CI 19.8-31.05; SE 2.8; p ≤ 0.001)]. Overall survival is poor and is driven mainly by the type of carcinoma. An Increased LRR might be present due to the systemic nature of the condition, and degree of control of the primary carcinoma