RISK FACTORS FOR THE DEVELOPMENT OF PERSISTENT SCAPHOID NONUNION AFTER NONUNION SURGERY

Between 2014 and 2020, 151 patients with an established scaphoid non-union (SNU) were enrolled in a prospective randomized trial evaluating the effect of Low Intensity Pulsed Ultrasound (the SNAPU trial) on healing in Scaphoid Non-Unions (SNU). All patients had surgery for an established SNU. At trial completion 134 of these patients had complete datasets with known union status. 114 (85%) of these patients went on to union and 20 (15%) went on to recurrent non-union. The main purpose of this study was to use this prospectively gathered data to identify patient, fracture, and surgery specific risk factors that may be predictive of persistent scaphoid non-union (PSNU) in patients who undergo surgery for SNU. Data were extracted from the SNAPU trial database. The inclusion and exclusion criteria of this study were the same as that of SNAPU trial. Nineteen risk factors were determined a priori. Risk factors included (among others): Sex, age, BMI, employment, WCB and smoking status, hand dominance, fracture classification, fracture fixation, specific bone grafting techniques, as well as time from injury to surgery and previous surgery for SNU. A stepwise multivariable logistic regression model was used to identify independent risk factors for PSNU. Only three risk factors were found to be independently significant predictors of persistent scaphoid non-union: age at time of surgery, dominant hand injury, and previous surgery on the affected scaphoid. With every decade of a patient's life, dominant hand injury, and previous scaphoid surgery, the odds of union are reduced by 1.72 times, 7.35 times, and 4.24 times, respectively. When operating on an established SNU, we identified three independent risk factors that predicted PSNU. Operations on the dominant hand, on previously operated scaphoids, and older patients showed strong correlation towards recurrent non-unions. The findings of this study are significant and may contribute to shared decision making and prognostication between the patient, surgeon, and affiliated members of their care team.