Posterior calcaneal spur length and angle are predictors of pain and functional limitation in insertional Achilles tendinopathy

Abstract

Objectives: This study aimed to quantitatively evaluate the clinical impact of posterior calcaneal spur (PoCS) morphology, specifically spur length and inclination angle, in patients with insertional Achilles tendinopathy (IAT).

Methods: This retrospective study analyzed 200 patients with symptomatic IAT who underwent standardized weight-bearing lateral ankle radiographs. Spur length and inclination angle were measured, and patients were stratified into nine subgroups based on three length categories (<5 mm, 5-10 mm, >10 mm) and three angle categories (<10°, 10-20°, >20°). Clinical outcomes were assessed using the Visual Analog Scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, and Victorian Institute of Sport Assessment-Achilles (VISA-A) score. Kruskal-Wallis tests and multivariate linear regression analyses were used to evaluate associations between spur morphology and outcomes.

Results: Both longer spurs (>10 mm) and steeper inclination angles (>20°) were significantly associated with worse clinical scores including higher VAS scores and lower AOFAS and VISA-A scores (P<0.001). Patients with spur lengths >10 mm and angles >20° had a mean VAS score of 7.22±0.65, VISA-A score of 49.72±2.54, and AOFAS score of 60.00±4.24, indicating greater pain and functional limitation. In contrast, patients with spur lengths <5 mm and angles <10° had lower VAS scores (5.18±0.82) and higher VISA-A (63.43±3.92) and AOFAS (72.57±4.33) scores, reflecting lower pain intensity and higher functional capacity (P < 0.001 for all). Regression analysis confirmed that spur length and angle were independent predictors of clinical outcome (P<0.001), while age, sex, and BMI were not statistically significant contributors (P>0.05).

Conclusions: Spur morphology - specifically length and angle - has a measurable impact on symptom severity in IAT. Radiographic evaluation of PoCS morphology should be integrated into clinical decision-making for more tailored management.

Keywords

• Posterior calcaneal spur
• insertional Achilles tendinopathy
• spur angle
• spur length

References

1. 1. Chatterton BD, Muller S, Roddy E. Epidemiology of posterior heel pain in the general population: cross-sectional findings from the clinical assessment study of the foot. Arthritis Care Res (Hoboken). 2015;67(7):996-1003. doi: 10.1002/acr.22546.
2. 2. Lawrence DA, Rolen MF, Morshed KA, Moukaddam H. MRI of heel pain. AJR Am J Roentgenol. 2013;200(4):845-855. doi: 10.2214/ajr.12.8824.
3. 3. Barg A, Ludwig T. Surgical Strategies for the Treatment of Insertional Achilles Tendinopathy. Foot Ankle Clin. 2019;24(3):533-559. doi: 10.1016/j.fcl.2019.04.005.
4. 4. Kang S, Thordarson DB, Charlton TP. Insertional Achilles tendinitis and Haglund's deformity. Foot Ankle Int. 2012;33(6):487-491. doi: 10.3113/fai.2012.0487.
5. 5. Chimenti RL, Cychosz CC, Hall MM, Phisitkul P. Current Concepts Review Update: Insertional Achilles Tendinopathy. Foot Ankle Int. 2017;38(10):1160-1169. doi: 10.1177/1071100717723127.
6. 6. Krishna Sayana M, Maffulli N. Insertional Achilles tendinopathy. Foot Ankle Clin. 2005;10(2):309-320. doi: 10.1016/j.fcl.2005.01.010.
7. 7. Grambart ST, Lechner J, Wentz J. Differentiating Achilles Insertional Calcific Tendinosis and Haglund's Deformity. Clin Podiatr Med Surg. 2021;38(2):165-181. doi: 10.1016/j.cpm.2020.12.003.
8. 8. Caudell GM. Insertional Achilles Tendinopathy. Clin Podiatr Med Surg. 2017;34(2):195-205. doi: 10.1016/j.cpm.2016.10.007.

9. 9. Şahin R, Sabri Balik M. Does the slope and length of the plantar calcaneal spur affect the clinic? Acta Orthop Belg. 2023;89(1):146-151. doi: 10.52628/89.1.10881.
10. 10. Bayrak HÇ, Topaktaş S. [Comparative Outcomes of Percutaneous Plantar Fascia Release, Calcaneal Drilling, and Calcaneal Spur Removal versus ESWT in the Treatment of Plantar Fasciitis]. Osmangazi J Med. 2025;47(3):457-466. doi: 10.20515/otd1634034. [Article in Turkish]
11. 11. Kuyucu E, Koçyiğit F, Erdil M. The association of calcaneal spur length and clinical and functional parameters in plantar fasciitis. Int J Surg. 2015;21:28-31. doi: 10.1016/j.ijsu.2015.06.078.
12. 12. Boberg JS, Anania MC. Retrocalcaneal exostosis. Anatomy and a new surgical approach. J Am Podiatr Med Assoc. 2002;92(10):537-542. doi: 10.7547/87507315-92-10-537.
13. 13. Delgado DA, Lambert BS, Boutris N, et al. Validation of Digital Visual Analog Scale Pain Scoring With a Traditional Paper-based Visual Analog Scale in Adults. J Am Acad Orthop Surg Glob Res Rev. 2018;2(3):e088. Epub 20180323. doi: 10.5435/JAAOSGlobal-D-17-00088.
14. 14. SooHoo NF, Shuler M, Fleming LL. Evaluation of the validity of the AOFAS Clinical Rating Systems by correlation to the SF-36. Foot Ankle Int. 2003;24(1):50-55. doi: 10.1177/107110070302400108.
15. 15. Robinson JM, Cook JL, Purdam C, et al. The VISA-A questionnaire: a valid and reliable index of the clinical severity of Achilles tendinopathy. Br J Sports Med. 2001;35(5):335-341. doi: 10.1136/bjsm.35.5.335.
16. 16. Chimenti RL, Flemister AS, Tome J, et al. Altered tendon characteristics and mechanical properties associated with insertional achilles tendinopathy. J Orthop Sports Phys Ther. 2014;44(9):680-689. doi: 10.2519/jospt.2014.5369.
17. 17. Kaya Ö, Demirtaş Y. [Is the presence radiologically calcaneal spur a factor for heel pain?] MKÜ Tıp Derg. 2022;13(47):281-285. doi: 10.17944/mkutfd.996223. [Article in Turkish]
18. 18. Tuncer T, Karakeci ES. Effectiveness of extracorporeal shock wave therapy according to plantar calcaneal spur types. Ann Med Res. 2023;30(5):549-53. doi: 10.5455/annalsmedres.2022.12.372.
19. 19. Fiamengo SA, Warren RF, Marshall JL, Vigorita VT, Hersh A. Posterior heel pain associated with a calcaneal step and Achilles tendon calcification. Clin Orthop Relat Res. 1982;(167):203-211.
20. 20. Lu CC, Cheng YM, Fu YC, Tien YC, Chen SK, Huang PJ. Angle analysis of Haglund syndrome and its relationship with osseous variations and Achilles tendon calcification. Foot Ankle Int. 2007;28(2):181-185. doi: 10.3113/fai.2007.0181.
21. 21. Nakajima K. Insertional Achilles tendinopathy: A radiographic cross-sectional comparison between symptomatic and asymptomatic heel of 71 patients. Eur J Radiol Open. 2024;12:100568. doi: 10.1016/j.ejro.2024.100568.
22. 22. Johansson KJ, Sarimo JJ, Lempainen LL, Laitala-Leinonen T, Orava SY. Calcific spurs at the insertion of the Achilles tendon: a clinical and histological study. Muscles Ligaments Tendons J. 2013;2(4):273-277.