SLR - March 2017 - Carolyn Winters

Clinical Outcomes of Nonunions of Hindfoot and Ankle Fusions

Reference: Krause F, Younger AS, Baumhauer JF, Daniels TR, Glazebrook M, Evangelista PT, Pinzur MS, Thevendran G, Donahue RM, DiGiovanni CW. Clinical Outcomes of Nonunions of Hindfoot and Ankle Fusions J Bone Joint Surg Am. 2016 Dec 7;98(23):2006–2016.

Reviewed By: Carolyn Winters, DPM
Residency Program: St. Francis Hospital, Hartford, CT

Podiatric Relevance: Arthrodesis is often indicated with joint degeneration resulting from diabetes, trauma, rheumatoid arthritis and congenital deformities. Approximately 11 percent of foot and ankle fusions result in nonunions. The purpose of this article was to identify the risk factors for nonunion after hindfoot and ankle fusions and to determine the impact of nonunion on clinical outcomes.  

Methods: Data from a prior level III prospective randomized clinical trial comparing graft materials on subjects requiring an ankle or hindfoot fusion was evaluated. This article aimed to focus on diagnosing nonunions based on CT assessment alone at 24 weeks (<25 percent bridging) versus surgeon composite assessment. The surgeon composite assessment consisted of evaluation of CT findings at 24 or 35 weeks (<50 percent bridging) as well as radiographic and clinical findings at 52 weeks. A total of 370 patients were evaluated in the CT group alone, and a total of 289 patients were evaluated in the surgeon assessment group. Once nonunion or union was determined, the subjects were further divided into one of four groups: nonunion defined using both assessments, union on both assessments, union on surgeon assessment/nonunion on CT, or nonunion on surgeon assessment/union on CT. A comparison of functional outcomes was assessed utilizing AOFAS-AHS, FFI and SF-12. BMI, smoking status, diabetes status, work status, age, sex and site of fusion were also noted.

Results:  
• Patients with a nonunion had significantly worse AOFAS-AHS, FFI, SF-12 and physical component summary scores, regardless of the nonunion assessment method.
• Asymptomatic nonunions were not supported in this study.
• Nonunions diagnosed by CT alone were more likely to be seen in patients who were overweight, nonworkers and smokers. There was no correlation found in the nonunions diagnosed by surgeon assessment.  
• Surgeon composite assessment revealed five percent nonunion rate, and CT assessment alone revealed 18 percent nonunion rate.
• Four percent of the patients had nonunion diagnosed utilizing both methods.

Conclusions: This study shows the importance of achieving union with fusion procedures to attain a good clinical outcome and therefore quality of life for the patient. It also suggests that certain demographics, including BMI, working status and smoking status, may predispose the patient to a poorer outcome. There were limitations in this study, including surgeon assessment of nonunions encompassing clinical outcome, lower fusion rates inherently seen in patients who underwent fusion of multiple joints (all joints treated had to demonstrate union), inconsistent definition of nonunion based on percentage of osseous bridging for the two assessment methods and a short follow-up course. Overall, achieving osseous union is necessary to ensure the patient has the best functional outcome. Future higher-level studies are needed to standardize the method of diagnosing union vs. nonunion and to further evaluate long-term outcomes.

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