Do weight-bearing films affect decision making in hallux valgus surgery?

Non-weightbearing compared with weightbearing x-rays in hallux valgus decision-making

OBJECTIVE

To report the effect of weightbearing x-ray imaging on clinical decisions in hallux valgus. Weightbearing (WB) x-ray is standard imaging for symptomatic hallux valgus (HV). In our clinical practice, often patients are presenting with non-weightbearing (NWB) x-rays. Repeated imaging requires additional radiation, justified only if expected to benefit patient's treatment. In this study, the influence of WB status on radiological HV parameters and on clinical decisions was analyzed.

METHODS

In the dataset of WB and NWB x-rays, the hallux valgus (HVA) and intermetatarsal angle (IMA) were measured and differences analyzed. Clinical decisions for 10 x-ray pairs were studied among 40 respondents.

RESULTS

The WB and NWB HVA difference ranged - 16 to 16° (p < 0.001) and IMA - 3.4 to 5.8° (p < 0.001). In only 45% of cases, the decisions based on NWB and WB imaging were consistent (kappa (95% CI) = 30.0 (23.7-36.3)).

CONCLUSIONS

Clinical decisions based on WB and NWB radiographs vary significantly. NWB films overestimate early and underestimate advanced HV deformity. Repeating radiographs is justified in patients presenting with NWB radiographs of symptomatic HV.

Intra- and Interobserver Agreement in Hallux Valgus Angle Measurements on Weightbearing and Non-Weightbearing Radiographs

The choice of treatment of hallux valgus deformity is influenced by angles measured on radiographs. Angles of interest are the hallux valgus angle (HVA), 1,2-intermetatarsal angle (IMA), and distal metatarsal articular angle (DMAA), as well as the presence of first metatarsophalangeal joint (MTPJ) subluxation. Guidelines for measuring those angles have been distributed by American Orthopaedic Foot and Ankle Society (AOFAS), although the influence of weightbearing on these angles and its clinical relevance is not clear. We conducted a study to determine the influence of weightbearing and the inter- and intraobserver agreement in the measurement. A total of 104 patients were enrolled in this study. Both weightbearing and non-weightbearing radiographs were obtained. In 2 rounds, 2 orthopedic surgeons and 2 musculoskeletal radiologists measured the angles in blinded digital radiographs according to AOFAS guidelines. Agreement on measurement of HVA, IMA, and DMAA in both weightbearing and non-weightbearing radiographs, as well as the presence of MTPJ subluxation, was calculated using the linear-weighted kappa coefficient and the intraclass correlation coefficient (ICC). Examiner agreement strength was defined according to the guidelines of Landis and Koch. HVA decreases significantly with weightbearing, whereas IMA significantly increases. The change in magnitude was 1° to 2° on average. No significant influence on DMAA could be noted. Interobserver agreement was excellent in both weightbearing and non-weightbearing radiographs for HVA (ICC 0.99 and ICC 0.99, respectively), IMA (ICC 0.98 and ICC 0.86, respectively), and DMAA (ICC 0.95 and ICC 0.97, respectively). The agreement on presence of subluxation was moderate to good (Fleiss kappa 0.50 to 0.63). Weightbearing alters forefoot geometry significantly. Adhering to AOFAS guidelines yields excellent interobserver agreement on HVA, IMA, and DMAA. First MTPJ subluxation presence is not an alternative for DMAA. The magnitude of change in IMA and HVA is small and therefore not clinically important. Both weightbearing and non-weightbearing radiographs can be used for determination of the correct treatment of hallux valgus deformity.

Radiographic Measurements of the Affected and Unaffected Feet in Patients with Unilateral Hallux Limitus A Case-Control Pilot Study

BACKGROUND

Controversy exists regarding the structural and functional causes of hallux limitus, including metatarsus primus elevatus, a long first metatarsal, first-ray hypermobility, the shape of the first metatarsal head, and the presence of hallux interphalangeus. Some articles have reported on the radiographic evaluation of these measurements in feet affected by hallux limitus, but no study has directly compared the affected and unaffected feet in patients with unilateral hallux limitus. This case-control pilot study aimed to establish whether any such differences exist.

METHODS

Dorsoplantar and lateral weightbearing radiographs of both feet in 30 patients with unilateral hallux limitus were assessed for grade of disease, lateral intermetatarsal angle, metatarsal protrusion distance, plantar gapping at the first metatarsocuneiform joint, metatarsal head shape, and hallux abductus interphalangeus angle. Data analysis was performed using a statistical software program.

RESULTS

Mean radiographic measurements for affected and unaffected feet demonstrated that metatarsus primus elevatus, a short first metatarsal, first-ray hypermobility, a flat metatarsal head shape, and hallux interphalangeus were prevalent in both feet. There was no statistically significant difference between feet for any of the radiographic parameters measured (Mann-Whitney U tests, independent-samples t tests, and Pearson χ(2) tests: P > .05).

CONCLUSIONS

No significant differences exist in the presence of the structural risk factors examined between affected and unaffected feet in patients with unilateral hallux limitus. The influence of other intrinsic factors, including footedness and family history, should be investigated further.

The Mechanical Axis of the First Ray: A Radiographic Assessment in Hallux Abducto Valgus Evaluation

The present report describes a new method of hallux abducto valgus deformity correction planning using the mechanical axis of the medial column (mechanical axis planning). This method of radiographic evaluation identifies an ideal position for the first metatarsal after correction and is useful regardless of the surgical procedure chosen. We retrospectively reviewed 200 radiographs to identify a "normal" value for the mechanical axis angle. We reviewed 100 radiographs of patients with hallux abducto valgus deformity (deformity group) and 100 radiographs of patients without hallux abducto valgus deformity (control group). The deformity group revealed an M1-M2 anatomic axis angle of 13.5° ± 2.83° and an M1-M2 mechanical axis angle of 11.58° ± 1°. The control group revealed an M1-M2 anatomic axis angle of 7.5° ± 1.76° and an M1-M2 mechanical axis angle of 11.19° ± 0.9°. The differences in the M1-M2 anatomic axis angle and M1-M2 mechanical axis angle were statistically significant between the control and deformity groups. We sought to provide a reliable method for planning hallux abducto valgus deformity correction by aligning the mechanical axis of the medial column and the mechanical axis of the first ray to the "normal" value of 11° to reduce the deformity.