Patients with rheumatoid arthritis (RA) have decreased ankle dorsiflexion due to gastrocnemius contracture, even in the absence of foot and ankle pain, according to research from Michigan that may have implications for early intervention to minimize pain and dysfunction in this patient population.
“We think that the tight gastrocnemius causes an increase in the tension on the plantar soft tissues, causing overuse and with time increasing the chance of having pathology,” said corresponding author James R. Jastifer, MD, an orthopedic surgeon with Borgess Orthopedics in Kalamazoo, MI.
The study included 70 patients (53 women) with a clinical diagnosis of RA after presenting to an orthopedic clinic with hand pain; the control group consisted of 70 participants (42 women) with no history of inflammatory arthritis or foot or ankle pain or injury.
All participants underwent measurement of their ankle range motion and isolated gastrocnemius contractures via clinical examination, goniometer, and a version of the previously validated Iowa ankle range of motion (IAROM) device. For all three measurement techniques, ankle dorsiflexion was significantly more limited in the RA group than in the control group. The findings were epublished by Foot & Ankle International in September.
Between-group differences in ankle dorsiflexion were greatest (12.3° vs 17.3°) when the IAROM device was used for measurement. For that assessment, patients had the knee extended and the tibia aligned perpendicular to the device’s foot plate, while the device’s axis of motion was aligned with that of the ankle. The authors noted that three measurements were taken with the hindfoot kept in neutral, while participants were encouraged to relax their leg muscles and keep their hip flexed to 90°.
Within the RA group, further analysis showed that the seven patients presenting with foot or ankle pain had 12.3° of ankle dorsiflexion compared with 12.5° in those with no pain, a difference that was not statistically significant. Sex, body mass index, age, and presence of inflammatory markers also were not significantly associated with ankle dorsiflexion.
Because there is a high incidence of foot and ankle pain in the general population of patients with RA, the study findings suggest limited ankle dorsiflexion contributes to this pain, and that limited ankle dorsiflexion in RA patients who do not yet have foot and ankle pain may represent an opportunity for intervention, such as stretching or orthotic management.
“Should we be screening for it? Should we be treating it with a stretching program? Maybe,” Jastifer said, noting further research is needed.
Patrick A. DeHeer, DPM, principal at Hoosier Foot & Ankle in Franklin, IN, agreed gastrocnemius equinus could contribute to foot and ankle pain in RA patients.
“Both pressure and biomechanical abnormalities associated with gastrocnemius equinus contribute to foot and ankle pain in the RA patient,” DeHeer said. “Increased forefoot and midfoot pressures produce obvious pathological stress on an at-risk forefoot.”
DeHeer said a critically important point of the Michigan study was the evaluation technique used, including supination of the foot while dorsiflexing the ankle joint with the knee extended.
Anthony Redmond, PhD, FFPM, RCPS(Glasg), FCPM, professor of clinical biomechanics at the Leeds Institute of Rheumatic and Musculoskeletal Med-icine in the UK, agreed with Jastifer that it is too early to determine the clinical implications of the findings.
“We cannot assume that an intervention, eg, stretches, would just ‘work’ in this population. There might be something about the joint damage, soft tissue fibrosis, pain, etcetera, that means the gastric shortening is irreversible. We need to do trials before rolling out intervention programs,” Redmond said. “Establishing whether there is a causal relationship between the [ankle dorsiflexion] observation and any symptoms is what needs to come next. Only then should we be throwing treatments at the problem.”
Jastifer JR, Green A. Gastrocnemius contracture in patients with rheumatoid arthritis. Foot Ankle Int 2017 Sep [Epub ahead of print]