Osteoarthritis of the first metatarsophalangeal joint (1st MTP joint OA) has been recognised as one of the most common causes of foot pain in middle-aged and older people [1
]. The condition affects 8% of individuals aged over 50 years and leads to disability, poorer health-related quality of life, and impaired locomotor function [1
]. 1st MTP joint OA is characterised by joint pain and stiffness, dorsal exostosis formation, and reduced 1st MTP joint dorsiflexion range of motion [2
]. The presence of adequate 1st MTP joint dorsiflexion is essential during the terminal stance and pre-swing phases of gait to enable smooth forward progression of the body over the foot [3
]. As a consequence of limited motion within the joint, individuals with 1st MTP joint OA adopt an altered gait pattern, characterised by reduced step length and shorter stance duration [4
Three studies have explored the relationship between clinical measurement of 1st MTP joint motion and dynamic function during walking, with inconsistent findings [3
]. In pain-free, healthy individuals, Nawoczenski et al. [3
] found significant associations between 1st MTP joint maximum dorsiflexion during walking and active weightbearing (Pearson’s r
= 0.80), passive weightbearing (r
= 0.61) and passive non-weightbearing (r
= 0.67) 1st MTP joint ROM. Similarly, in asymptomatic individuals, Jarvis et al. [6
] found a significant association (r
= 0.32) between 1st MTP joint maximum dorsiflexion and maximal dorsiflexion during walking. In contrast, Halstead et al. [7
] found no significant association between passive 1st MTP joint maximum dorsiflexion and 1st MTP joint maximum dorsiflexion during walking in individuals with limited 1st MTP joint motion (as determined by Jack’s test [8
] in relaxed standing). To the best of our knowledge, no studies have examined this association in individuals with radiographically-confirmed 1st MTP joint OA.
Therefore, the primary aim of this study was to determine whether there is an association between passive non-weightbearing (NWB) 1st MTP joint maximum dorsiflexion and sagittal plane kinematics in individuals with radiographically confirmed 1st MTP joint OA. Doing so will provide insight into the underlying mechanisms responsible for gait alterations in individuals with this condition.
This study examined the relationship between passive NWB 1st MTP joint maximum dorsiflexion and sagittal plane kinematics in individuals with 1st MTP joint OA. Our findings indicate that individuals with less passive NWB 1st MTPJ maximum dorsiflexion exhibit less 1st MTP joint maximum dorsiflexion, less ankle joint maximum plantarflexion and ankle joint excursion during level walking. The magnitude of these associations was moderate, with r2
values indicating that passive NWB 1st MTP joint maximum dorsiflexion can explain approximately 24, 15 and 16% of 1st MTP joint maximum dorsiflexion, ankle joint maximum plantarflexion and ankle joint excursion, respectively. These findings are consistent with previous studies that indicate the reduction in range of motion associated with OA impairs the normal propulsive function of the foot [4
Passive NWB 1st MTP joint maximum dorsiflexion in our sample ranged from 17 to 62 degrees, with a mean of 45 degrees. Using the same measurement technique in a population-based study of 517 people aged over 50 years with foot pain, Menz et al. [2
] found that passive NWB 1st MTP joint maximum dorsiflexion was associated with the radiographic severity of OA, with the most severe radiographic category demonstrating a mean value of 42 degrees. This similarity suggests that our participants were towards the more severe end of the radiographic spectrum, which would be expected given that their reported duration of OA symptoms was 4 years. 1st MTP joint maximum dorsiflexion during gait in our study ranged from 14 to 40 degrees, with a mean of 25 degrees. Despite using different kinematic models, this is similar to the mean value reported by Canesco et al. (approximately 30 degrees) in 22 patients undergoing surgery for hallux rigidus [4
The associations reported here are consistent with Nawoczenski et al. [3
] and Jarvis et al. [6
], who found significant correlations between passive NWB and dynamic 1st MTP joint dorsiflexion in a pain-free healthy populations (r =
0.67 and r
= 0.32, respectively). In contrast, Halstead et al. reported no significant association between passive and dynamic 1st MTP joint dorsiflexion (r =
]. However, in the Halstead et al. study, participants had limited passive 1st MTP joint maximum dorsiflexion in relaxed standing (positive Jack’s test [8
]), but normal (> 50 degrees) of passive NWB 1st MTP joint maximum dorsiflexion, indicative of “functional” hallux limitus. Our study, therefore, is the first to examine this association in individuals with symptomatic, radiographically-confirmed 1st MTP joint OA.
We found a significant positive association between passive NWB 1st MTP joint maximum dorsiflexion and ankle joint maximum plantarflexion during gait, which suggests that limited 1st MTP joint dorsiflexion may impair efficient propulsion. The presence of strategies to compensate for limited 1st MTP joint dorsiflexion has been reported in previous studies, where there was an increase in lateral forefoot loading and reduced ankle joint plantarflexion in the presence of 1st MTP joint OA [5
]. These findings have previously been linked with the high- and low-gear push-off concept proposed by Bojsen-Moller [20
], whereby individuals with limited 1st MTP joint dorsiflexion fail to efficiently utilise the high-gear transverse axis (connecting the 1st and 2nd metatarsal heads) resulting in motion occurring through the low-gear oblique axis (connecting 2nd to 5th metatarsal heads) [5
]. The low-gear propulsion causes a shorter lever arm between the ankle joint plantarflexors and forefoot, subsequently resulting in a higher lateral loading pattern and less efficient propulsion [5
]. However, further kinematic and kinetic analyses are required to confirm this proposed mechanism.
This study has several methodological strengths, including radiographic confirmation of 1st MTP joint OA using a standardised atlas, a relatively large sample size for a kinematic study, and use of a reliable clinical measurement of passive NWB 1st MTP joint maximum dorsiflexion. However, the results of the study should be interpreted with respect to three key limitations. Firstly, due to the cross-sectional study design we cannot infer causality between passive NWB 1st MTP joint maximum dorsiflexion and kinematic changes. Secondly, kinetic data were not collected in this study, which would have allowed greater insight into the loading of the 1st MTP joint. Thirdly, our kinematic foot model was a simplified version of the Salford Foot Model [14
], as participants needed to be tested while shod as part of the larger clinical trial. This precluded any analysis of the motion of the midfoot, which has been shown to be significantly altered in the presence of 1st MTP joint OA [4
]. Finally, because participants were tested shod, we cannot exclude the influence of footwear on 1st MTP joint kinematics. However, the shoes used were of minimalist design with removal of large sections of the upper to accommodate the markers, so they were unlikely to have substantially influenced foot function.
In conclusion, this study identified that individuals with less passive NWB 1st MTP joint maximum dorsiflexion exhibit less dynamic 1st MTP joint maximum dorsiflexion, less ankle joint plantarflexion and less total ankle joint excursion during level walking. These findings suggest that clinical measurement of the 1st MTP joint provides useful insights into the dynamic function of the foot and ankle in this population. However, further study is required to determine the clinical importance of these observations.
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