A cross-sectional study explaining relationship between patient-reported outcome measures (PROM) and three measures of foot–ankle alignment (MoFAA) in patients with metatarsal head pain
The three measures of foot-ankle alignment (MoFAA) correlated between moderately to strongly with the foot–ankle PROM selected and these results would help in future to develop tools for evaluating and monitoring patients with metatarsal head pain.
Nontraumatic foot problems are known to affect more than 20% people over 65 years, and about 60% of these issues are restricted to forefoot. The most common cause of foot consultation is the metatarsal head pain.
Patient assessment and monitoring involved objective clinical outcome measures (OCOM) and patient-reported outcome measures (PROM). While OCOM offered consistency and validity degree and encourage trust in results, PROM used as a daily practice tool to quantify a patient's perception of disability, health, and quality of life. Both these measures aid in normalizing results, decrease errors and increases understanding for patients and clinicians both.
As per biochemical approach, the first ray is a central element in regulating the structural integrity of the foot, facilitating forward progression during walking and generating the windlass mechanism. Biomechanical disorders of the first ray are an essential factor of several pathologies of the feet. Also, in adults, hindfoot valgus is linked with both Hallux valgus and Hallux limitus/rigidus. Metatarsal–phalangeal joint (MTPJ) extension, navicular drop (ND) test and forefoot varus angle (FVA) are the three measures of foot–ankle alignment (MoFAA) that are frequently used in the evaluation and monitoring of patients with foot–ankle disorders. Likewise, the Foot Health Status Questionnaire (FHSQ), Foot Function Index (FFI) and the American Academy of Orthopaedic Surgeons' Foot and Ankle Module (AAOS-FAM) are commonly used in PROM in the evaluation of a patient’s perception of foot–ankle disorders.
Earlier studies have demonstrated the effectiveness of relating PROM and OCOM variables to different body regions like back or knee, and to different population groups like patients with intellectual incapacities or low back pain.
Rationale behind the research
Till now, no study has examined and compared the association between the PROM and MoFAA (OCOM) and focused on the evaluation and monitoring of patients with metatarsal head pain. The present study can be used as a standard to develop tools or procedures for evaluation and monitoring patients with metatarsal head pain.
- To build the association between foot–ankle PROM and MoFAA, which are used in daily clinical practice for evaluating and monitoring those patients with metatarsal head pain.
To examine how each of the three PROMs selected is predicted by the three MoFAA chosen.
Note: The Kolmogorov–Smirnov test was used to test the normality of measurements. Also, as a measure of control, MoFAA reliability was calculated through intraclass correlation coefficients (ICCs - CI 95%). The reliability was considered the consistency of MoFAA Measures of reliability were stratified as follows: ICC≤0.40 (poor), 0.60>ICC>0.40 (moderate), 0.80>ICC≥0.60 (good), ICC≥0.80 (excellent)]. A correlation analysis between MoFAA and PROM was performed using Pearson's coefficient, which was stratified into different levels: r≤0.49 (poor), 0.50≤r≤ 0.74 (moderate), and r≥0.75 (strong). All MoFAAs (left and right side) were incorporated as predictors in all regressions calculated (six variables in total for each model). Also, standardized beta coefficients for each of the models were calculated. Normalised navicular drop test measures were used to calculate the relationship between MoFAA and PROMs variable
- Patient-reported outcomes
- The FHSQ Questionnaire: It is designed to measure the quality of life-related to foot health. This questionnaire used four subscales (foot pain, foot function, footwear and general foot health. FHSQ scores vary from 0 to 100, 0 being the worst and 100 stands for best foot health status.
- The FFI Questionnaire: It is a widely used tool for the evaluation and management of patients with different origins of foot diseases. It comprises a general index and three subscales that assess specific aspects of the foot: pain, disability, and activity limitation. The FFI score range between 0 (best foot function) to 100 (worst foot function).
- The AAOS-FAM Questionnaire: It is an instrument designed to evaluate patients’ perception of their foot health, and measure surgical outcomes. It presents an overall value and two subscales: global foot and ankle scale and shoe comfort scale. AAOS-FAM ranges from 0 to 100 where 0 is the worst and 100 is the best foot health.
Measures of three MoFAA by researchers: Similar to PROMs, all three MoFAA were measured in a randomized order to reduce bias from questionnaire fatigue.
- The MoFAAs intra-observer reliability value was of 0.942 (ND test), 0.957 (first MTPJ extension) and 0.919 (FVA). Inter-observer reliability (ICC–CI 95%) was 0.877, 0.891 and 0.861 for the ND test, first MTPJ extension and FVA, respectively.
- Most correlations were significant, although the index value changed in each PROM used. Thus, in the AAOS-FAM questionnaire, correlation indices ranged from 0.243 (Shoe Comfort Scale–FVA right) and 0.686 (AAOS-FAM Index–first MTPJ extension right). In the FHSQ, correlation indices ranged from 0.282 (Shoe Comfort Scale–FVA right) to 0.643 (Foot Function–first MTPJ extension right). Finally, FFI correlation values ranged from 0.527 (Activity Limitations–FVA left) to 0.807 (FFI Index–first MTPJ extension right).
- Regression indices (R2 corrected) ranged between 0.117 (AAOS-FAM–Shoe Comfort Scale) and 0.701 (FFI Index).
- The independent variable that offered most of the values of regression is the first MTPJ extension, accompanied by the ND test and the FVA. Also, the dependent variables had lower regression index values than those that were related to footwear, which made the most significant contribution to FVA
Table 1: Standardized Beta coefficients of each independent variable (MoFAA) for each dependent variable (PROM index and sub-scales)
1st MTPJE first metatarsalphalangeal joint, AAOS FAM AAOS foot and ankle module, FHSQso Foot health status questionnaire spanish version, GFH General foot health, FFI Foot functional index
Till date, no study analyzed the relationship between MoFAA and PROM for patients' assessment and management of metatarsal head pain; therefore, it was not possible to compare the results of similar studies. Though, recent studies conducted on other body regions showed high applicability in finding a relationship between MoFAA and PROM variables, such as to create a biased rate in people with chronic, non-specific low back pain, to be used as a strength predictor index in the rehabilitation processes in the ACL. Similarly, the results obtained in this study could be used in future studies to develop tools for evaluating and monitoring patients with metatarsal head pain.
The results of the present study demonstrated that the MoFAA correlated between moderately to strongly with the foot–ankle PROM selected. MoFAA showed the highest influence on FFI index, which could mean that FFI index more effectually signifies the association between the objective physical state of the patient's feet and the patient's insight on the condition of his/her feet. When patients with metatarsal head pain were asked about foot health status, pain and function; the influence level was higher; however, the influence level was reduced when the patients were asked about shoe aspects. Finally, the MoFAA variable achieved the highest correlation value: first, the MTPJ extension, followed by the ND test and the FVA.