Is There a Difference in PROMIS Outcomes Between Patients Who Received K-Wire or Intramedullary Implant PIP Joint Arthrodesis for Hammertoe Deformity?
Authors: Holleran Amanda M. , Homeier Daniel , Baumhauer Judith F. , Flemister Adolph S. , Oh Irvin , DiGiovanni Benedict F. , Ramirez Gabriel A. , Thirukumaran Caroline , Ketz John P. 
Published: January 2022

Category: Lesser Toes Introduction/Purpose: Hammertoe corrective procedures are common foot and ankle procedures. Traditionally Kirshner wire (K-wire) fixation has been the gold standard in terms of fixation. Due issues such as pin loosening, failure, tract infection, fibrous pseudoarthrosis, and recurrent deformity with K-wire fixation, newer intramedullary implants have become widely used in the foot and ankle community. These implants have increased cost compared to K-wire fixation. The primary purpose of this study is to evaluate PROMIS T-scores for physical function (PF), pain interference (PI), and depression domains in patients who have undergone PIP arthrodesis by either K-wire or intramedullary fixation. The secondary goal is to determine if there are any differences in these two fixation groups in regard to complication or recurrence rates. Methods: From January 2010 to November 2019, prospective Patient Reported Outcome Measure Information System (PROMIS) score data was retrospectively reviewed for patients who had undergone a hammertoe deformity correction at a multi- surgeon tertiary foot and ankle clinic. Inclusion criteria was patient's older than 18 years, failed conservative management, undergone correction of lesser toe deformity with either K wire fixation or intramedullary fixation. Exclusion criteria was inadequate PROMIS data, previous fracture in same toe, revision surgery, both K wire and intramedullary fixation in the same toe. Preoperative scores were evaluated compared to postoperative scores at multiple time points. Chart review was also performed for patient demographics, complications, and revision surgery. PROMIS physical function (PF), depression, and pain interference (PI) scores were evaluated. Patients with incomplete data sets were excluded from the study. Complications and number of reoperations were noted for each group. Results: 252 patients met inclusion criteria, 111 and 138 patient in the intramedullary (IM) and K-wire groups (KW) respectively. Univarate analysis demonstrated significant improvement in PROMIS PF and PI in IM group compared to KW group. Multivariate analysis demonstrated the following: KW group demonstrates a 2.9 point decrease in PROMIS PF post-operative scores relative to the IM group (95% CI -4.75 to -0.99; p = 0.003). The IM implants had significantly higher PF scores than the K-wire group at final follow up (p<0.05). BMI, smoking, and Medicare/Medicaid insurance demonstrated worse PF scores (p<0.05). PROMIS PI did not demonstrate a difference between groups (95% CI -0.377 to 3.724; p = 0.110). The KW group did not demonstrate increase recurrance rate (OR 0.348 95% CI 0.118-1.027; p = 0.056), but did trend towards a higher complication rate compared to the IM group (OR 2.049, 95% CI 0.92 to -4.54; p = 0.078). Conclusion: There is evidence that use of intramedullary implants for operative correction of hammertoe deformity is superior to K-wire fixation in regard to post-operative patient reported measures, specifically the PROMIS domains of physical function. Intramedullary implant use does not increase complication or recurrence rates. Additionally, advanced age, increased BMI, positive smoking status, and Medicare or Medicaid payor status negatively affect patient reported outcomes, which can be used to council patients appropriately. The limitations are that cost of intramedullary implants, are more expensive when compared to conventional K-wires.