Patients

This retrospective comparative study included consecutive patients with complete pathological fractures or metastatic impending pathological fracture of the proximal humerus who were treated surgically in our institution between January 2011 and January 2022. Pathological fractures of the proximal humerus were defined as metastatic lesions in the humeral neck or proximal humerus leading to imminent or complete fractures. Prior to undergoing surgery, all patients consulted with an oncologist and anesthesiologist regarding perioperative risks and life expectancy. Inclusion criteria were: (1) symptomatic impending or complete pathological fracture and (2) life expectancy of more than 3 months. Exclusion criteria were: (1) life expectancy of less than 3 months, (2) preoperative American Society of Anesthesiology (ASA) grade 4, (3) extensive lesion involving the articular surface. When selecting the implant, the histology of the primary tumor was not considered. A total of 45 patients were included for final analysis, including 13 and 12 patients with multiple and solitary bone metastases, respectively. Seventeen cases were treated with intramedullary nailing plus cement augmentation, while 28 cases were treated with locking plate plus cement augmentation, depending on physician judgment (Fig. 1). All cases were treated based on the same criteria. The differences lie in the early stages of treating pathological humerus fractures, before the widespread use of the nailing system, when plates were commonly employed as the “standard procedure.” However, as our experience using humeral nails for the treatment of fractures progressed and we became increasingly proficient, this technique was gradually applied more often to these pathological fracture cases. A minimum follow-up period of 12 months was achieved for those who survived.

Fig. 1

Flowchart of patient selection

Ethical considerations

The study protocol was reviewed and approved by the Institutional Review Board. Because of the retrospective design of the study and anonymity of the patients, signed informed consent was waived.

Surgical procedure: intramedullary nailing with cement augmentation

The patient was semi-sitting, and the surgery was performed under general anesthesia. A limited anterolateral approach was made for tumor curettage and nail insertion. The axillary nerve was identified and protected whenever possible. All gross tumors were removed as much as possible. Curettage through the fracture gap usually resulted in a cortical bone defect, enough for cement impaction when the fracture was complete. A cortical window was made in the thinnest cortex wall on the anterolateral proximal humerus when the fracture was impending. After meticulous curettage of gross tumors, local adjuvant therapy of 95% alcohol was applied. Then the nail (DePuy Synthes, MultiLoc Humeral Nails, Raynham, MA, USA) was inserted in an antegrade manner after series remaining to desired width. The nail should be long enough to cover the entire humerus. The nail-end position was carefully checked and buried about 5 mm below the articular surface of the humerus head because the need for nail removal in the future was not expected and the goal was to avoid nail impingement to rotator cuff tendons. For fixation, we usually applied two or three proximal screws and one or two distal screws. The bone defect was filled by poly(methyl methacrylate) bone cement after nail fixation. Early range of motion was encouraged the next day after surgery. A rehabilitation program such as passive stretching or gravity-resistant exercise was arranged about 1 week later. Adjuvant external beam radiation with 3000–3500 Gy was performed for most patients. Since reaming was used for better size nail insertion, radiotherapy was deemed necessary for local tumor control owing to the risk of tumor dissemination after reaming.

Surgical procedure: humerus plating with cement augmentation

The surgery was performed applying the same basic principles as nailing. An anterolateral approach was made to directly expose the fracture site or gross tumor part with the patient in a semi-sitting position. The axillary nerve wound was also protected whenever possible. After meticulous tumor curettage, local adjuvant therapy of 95% alcohol was applied. Then poly (methyl methacrylate) (PMMA) cement was infilled into the skeletal defect. A proximal humerus locking plate (DePuy Synthes, Inc., Philos® System, Raynham, MA, USA) was placed and inserted with appropriate size screws for fixation. The plating group shared the same postoperative protocol as the nailing group. Adjuvant external beam radiation with 3000–3500 Gy was performed for most patients.

Outcomes

The primary outcomes were pain relief and functional status, and the secondary outcome was perioperative complications. Visual analog scale (VAS) scores were evaluated to monitor pain improvement from before surgery to 1 week and 1 month after surgery. Functional status was assessed by the shoulder joint range of motion such as forward flexion and abduction 1 month after surgery, and the Musculoskeletal Tumor Society rating scale (MSTS) and Karnofsky performance status scale were used 3 months postoperatively. Perioperative parameters such as operative time, blood loss, and hospital length of stay were also recorded. Possible complications included radial nerve injury, shoulder impingement, infection, implant failure, or revision surgeries.

Statistical analysis

Normally distributed continuous data are presented as mean ± standard deviation (SD) and evaluated by Student’s t-test; non-normally distributed continuous data are presented as median and interquartile range (IQR) and analyzed by Wilcoxon rank-sum test. Shapiro–Wilk test for normality was used for testing normal distribution of variables. Categorical data are presented as counts and percentages and analyzed by chi-square or Fisher’s exact test. Kaplan–Meier survival analysis was used to evaluate the reliability of each group and the overall survival of patients. All p-values are two-sided, and p < 0.05 was considered statistically significant. All statistical analysis was performed using SAS software version 9.4 (SAS Institute Inc., Cary, NC, USA).

Literature review

The review was performed in accordance to PRISMA guidelines. Medline, and Cochrane, and Google Scholar database were searched until 15 November 2022 for studies that evaluated effects of surgical treatments in treating metastatic pathological fracture of the proximal humerus. The following search terms were used: proximal humerus, metastatic pathological fracture, surgery, endoprosthesis replacement, locking plate, and nailing. Included studies were those that evaluated outcomes of endoprosthesis replacement, plating with cement, or intramedullary nailing with cement in patients diagnosed with metastatic pathological fractures of proximal humerus. Letters, editorials, comments, and case reports were excluded from the systemic review. Studies were identified and manually searched by at least two independent reviewers. When there was uncertainty regarding eligibility, a third reviewer was consulted. The following information and data were extracted from included studies: name of first author, year of publication, surgical mode, number of participants, participants’ age, postoperative function level, pain control level, complications, tumor recurrence, reoperation.