Prevalence of isolated gastrocnemius tightness in patients with foot and ankle pathology – a population based study

Abstract

Category: Other Introduction/Purpose: Gastrocnemius tightness (GT) is thought to predispose patients to multiple musculoskeletal pathologies including back pain, plantar fasciitis, and metatarsalgia. It is thought to be especially prevalent in patients with foot and ankle pathology (FAP) and consequently there is an emerging trend to perform lengthening / release procedures in this patient group. However, it is not clear what proportion of the normal population has GT and how this differs in patients with FAP. We set out to investigate what the incidence and degree of GT in the foot and ankle population is compared to the normal population. Methods: This was a prospective study comparing GT in a cohort of patients with FAP with GT in controls matched for age, gender, and ethnicity. The control group consisted of healthy adult volunteers and the FAP group consisted of patients presenting to our Foot & Ankle unit. Patients with previous surgery, tendoachilles tightness, or ankle arthritis were excluded. GT was measured using a digital inclinometer and the lunge test. It was calculated as the difference between maximal ankle dorsiflexion with the knee extended and with the knee flexed. Data on the control group was collected first and a power calculation suggested a FAP cohort size of 91 feet was required to detect a 2° difference in GT (a= 0.05, ß = 0.05, Ratio 3:1). Results: After case-matching 97 FAP cases were paired with 291 controls for analysis. Mean GT was 8.0° ±5.7° (range: 0-21°) in FAP patients versus 6.0° ±3.5° (range: 0-16°) in controls (p<0.001). Regression analysis demonstrated demographics including BMI and activity level were not significant determinants of GT in the FAP group (r=0.141, p=0.599). Subgroup analysis of the FAP group revealed a mean GT of 10.3° ±6.0° in patients with forefoot pathology (FoP) versus 6.9° ±5.3° in the other FAP patients (NFoP) (p=0.008). When comparing the NFoP group to the controls, there was no difference in GT (p=0.188). In total 21 FAP patients (21.6%) and 12 FoP patients (37.5%) had GT greater than 2 standard deviations of the control group (Figure 1). Conclusion: This population based study demonstrates increased GT in the FAP population versus the normal population; however, in patients without forefoot pathology, this difference may not be clinically relevant. Over a third of patients with forefoot pathology have GT which is greater than the normal population range. We conclude that not all patients with foot and ankle pathology have inherently increased GT, compared with the normal population, but it is reasonably common in patients with forefoot pathology. Further work is required to define what degree of GT may be considered significant, to determine which patients will benefit from surgical treatment.