Association of Haglund Deformity Size and Insertional Achilles Tendinopathy.

Background: We aimed to investigate the effect of Haglund deformity size on insertional Achilles tendinopathy (IAT) using a new measurement system and identify independent risk factors of IAT with Haglund deformity.

Methods: We reviewed medical records of patients with IAT and age/sex-matched patients with diagnoses other than Achilles tendinopathy. Radiographs were reviewed to identify posterior heel spur, plantar heel spur, and intra-Achilles tendon calcification, and to measure Fowler-Philip angle, calcaneal pitch angle, and Haglund deformity angle and height. We introduced a new measurement system for Haglund deformity angle and height and evaluated its intraobserver and interobserver reliability. Multivariate logistic regression analysis was performed to identify independent risk factors of IAT with Haglund deformity.

Results: Fifty patients (55 feet) were enrolled in the study group, equaling the size of the age/sex-matched control group. The new Haglund deformity measurement system showed excellent intraobserver and interobserver reliability. No significant differences between the 2 groups were noted in Haglund deformity angle and height: 6.0 degrees in both groups, and 3.3 mm vs 3.2 mm in the study and control group, respectively. The study group had significantly higher calcaneal pitch angle, incidence of posterior heel spur, plantar heel spur, and intra-Achilles tendon calcification: 5.2 vs 23.1 degrees (P = .044), 81.8% vs 36.4% (P < .001), 76.4% vs 34.5% (P = .003), and 67.3% vs 5.5% (P < .001), respectively. Multivariate logistic regression analysis identified independent risk factors of IAT: posterior heel spur (OR = 3.650, 95% CI = 1.063, 12.532), intra-Achilles tendon calcification (OR = 55.671, 95% CI = 11.233, 275.905), and increased calcaneal pitch angle (OR = 6.317).

Conclusion: Based on our results, the actual size of Haglund deformity as we have reliably measured was not associated with IAT, suggesting a routine Haglund deformity resection may be unnecessary in the surgical treatment of IAT. If patients with Haglund deformity have posterior heel spur, intra-Achilles tendon calcification, or increased calcaneal pitch angle, a higher chance of IAT can be predicted.

Level of evidence: Level III, retrospective cohort study.