Clinical Biomechanical Measurements And EBM: Where Do We Draw The Line?

There are several traditions in medicine that are not scientifically based but continue as practice doctrine. Many of these traditions are the basis for the diagnosis and treatment of foot and ankle pathologies. In the evolving world of evidence-based medicine, we should question a tradition that is not scientifically based.

Foot and ankle surgeons commonly utilize clinical biomechanical measurements of the lower extremity despite the lack of evidence. Foot and ankle surgeons measure everything from forefoot position for orthotic posting to first metatarsophalangeal joint (MPJ) range of motion (ROM) to determine surgical approaches for hallux limitus.

In a recent article in Foot and Ankle International, Vulcano and colleagues examined the reliability of clinical measurement of first MPJ ROM in comparison to a new radiographic analysis.¹ The study showed a mean difference between the two measurements to be 13 degrees with the difference significantly greater in the group of patients with less than 30 degrees of first MPJ ROM. The radiographic measurement showed good intra- and inter-observer reliability while the clinical examination showed poor reliability.

Van Gheluwe and coworkers revealed inter-rater reliability for lower extremity biomechanical measurements to be poor, but intra-rater reliability to be relatively high.² The study evaluated 14 different lower extremity biomechanical measurements and other than relaxed calcaneal stance position and forefoot varus position, the intra-class correlation coefficients were 0.51. Elveru and colleagues showed similarly poor inter-rater results for subtalar inversion, eversion and ROM, and ankle dorsiflexion while ankle plantarflexion was moderately high.³ In another study, Javis and colleagues concluded, “Static biomechanical assessment of the foot, leg and lower limb is an important protocol in clinical practice, but the key examinations used to make inferences about dynamic foot function and to determine orthotic prescription are unreliable.”⁴

What is the practicing foot and ankle surgeon to do with this quagmire? A consistent finding from these studies is that intra-rater reliability was reasonably reproducible. Even though inter-rater reliability was poor, consistent results from a single physician can provide the basis for proper documentation and comparative analysis. I think the experienced physician can interpret normal from varying degrees of abnormal with clinical examination. When I document biomechanical exam findings, I often use mild, moderate and severe to grade findings. Documentation such as this means something to me but for another physician, it may have an entirely different meaning. This form of documentation is no better or worse than clinical measurements.

The take-home message from these findings should be that your clinical measurements can serve as a valid reference for your documentation but you should not rely on the measurements of another physician.

References

1. Vulcano E, Tracey JA, Myerson MS. Accurate measurement of first metatarsophalangeal range of motion in patients with hallux rigidus. Foot Ankle Int. 2015; epub Dec. 9.
2. Van Gheluwe B, Kirby KA, Roosen P, Phillips RD. Reliability and accuracy of biomechanical measurements of the lower extremities. J Am Podiatr Med Assoc. 2002; 92(6):317-326.
3. Elveru RA, Rothstein JM, Lamb RL. Goniometric reliability in a clinical setting subtalar and ankle joint measurements. Physical Therapy. 1988; 68(5):672-677.
4. Jarvis HL, Nester CJ, Jones RK, et al. Inter-assessor reliability of practice based biomechanical assessment of the foot and ankle. J Foot Ankle Res. 2012; 5(14):2.