Thirty-five studies (n=2,054) were included: 2 RCTs (n=69), 6 prospective cohort studies (n=215) and 27 retrospective cohort studies (n=1,770). Twelve studies assessed both medial and lateral entry pinning and lateral entry only (n=776), 18 assessed medial and lateral pinning only (n=865) and 5 evaluated lateral entry pinning only (n=413).
The authors reported that in two of the prospective studies the loss to follow-up was 16% and 32%. The remaining prospective studies had a loss to follow-up of less than 10%.
The incidence of iatrogenic nerve injury was 3.5% in the medial and lateral injury group and 1.9% in the lateral entry only group. Medial and lateral entry pinning was associated with a significantly greater risk of iatrogenic nerve injury compared to pinning with lateral entry alone (RR 1.84, 95% CI: 1.01, 3.36, p<0.04). This risk increased when only ulnar injuries were considered. Medial and lateral entry pinning was five times more likely to result in ulnar nerve injury than lateral entry pinning alone (RR 5.04, 95% CI: 2.00, 12.72, p<0.0001).
The incidence of deformity was 3.4% in the medial and lateral entry group compared with 5.9% in the lateral entry only group. Medial and lateral entry pinning was associated with a statistically significant decrease in the risk of deformity (RR 0.58, 95% CI: 0.36, 0.93, p<0.02).
However, when a subgroup analysis was conducted of prospective studies only, no significant differences were found between the different procedures for all of the outcomes.