Our aim was to ascertain if K-wire configuration had any influence on the infection and complication rate for base of 4th and 5th metacarpal fractures. We hypothesised that in individuals whose wires crossed the 4th and 5th carpometacarpal joint (CMCJ), the rate of complications and infection would be higher.

Data was retrospectively analysed from a single centre. 106 consecutive patients with a base of 5th (with or without an associated 4th metacarpal fracture) were analysed between October 2016 and May 2021. Patients were split into two groups for comparison; those who did not have K-wires crossing the CMCJ's and those in whose fixation had wires crossing the joints. Confounding factors were accounted for and Statistical analysis was performed using SPSS version 20 software.

Of 106 patients, 60 (56.6%) patients did have K-wires crossing the CMCJ. Wire size ranged from 1.2-2.0 with 65 individuals (65.7%) having size 1.6 wires inserted. The majority of patients, 66 (62.9%) underwent fixation with two wires (range 1-4). The majority of infected cases (88.9%) were in patients who had k-wires crossing the CMCJ, this trended towards clinical significance (p=0.09). Infection was associated with delay to theatre (p=0.002) and longer operative time (p=0.002).

In patients with a base of 4th and 5th metacarpal fractures, we have demonstrated an increased risk of post-operative infection with a K-wire configuration that crosses the CMCJ. Biomechanical studies would be of use in determining the exact amount of movement across the CMCJ, with the different K-wire configuration in common use, and this will be part of a follow-up study.

Our aim was to explore factors associated with early post operative infection for surgically managed base of 4th/5th metacarpal fractures. We hypothesised that K-wires crossing the 4th and 5th carpometacarpal joint (CMCJ) would be associated with an increased risk of post-operative infection.

Data from consecutive patients requiring surgical fixation for a base of 4th/5th metacarpal fracture from October 2016 to May 2021 were collected. Patient demographics, time to surgery, length of surgery, operator experience, use of tourniquet, intra-operative antibiotics, number and thickness of K-wire used, as well as whether or not the K-wires crossed CMCJ joints were recorded. Factors associated with post operative infection were assessed using Chi Squared test and univariable logistic regression using R studio.

Of 107 patients, 10 (9.3%) suffered post operative infection. Time to surgery (p 0.006) and length of operation (p=0.005) were higher in those experiencing infection. There was a trend towards higher risk of infection seen in those who had K-wires crossed (p=0.06). On univariable analysis, patients who had wires crossed were >7 times more likely to experience infection than those who didn't (OR 7.79 (95% CI, 1.39 - 146.0, p=0.056). Age, smoking, K-wire size, number of K-wires used, intraoperative antibiotics, tourniquet use and operator experience were not associated with infection.

In patients with a base of 4th/5th metacarpal fractures requiring surgical fixation, we find an increased risk of post-operative infection associated with K-wires crossing the CMCJ, which has implications for surgical technique. Larger prospective studies would be useful in further delineating these findings.