Previous dye-infusion experiments on cadavers have suggested that the hindfoot should be divided into four muscle compartments including a newly described ‘calcaneal’ element containing quadratus plantae. Since there are no clinical data to support this proposed division, we re-examined the validity of the infusion experiment. We made infusions of dilute Omnipaque at a constant rate into flexor digitorum brevis of four cadaver feet. We monitored the spread of the infusate by real-time CT imaging and measured the pressures at the infusion site by side-ported needles.

In all feet, the barrier between flexor digitorum brevis and quadratus plantae became incompetent at pressures of less than 10 mmHg. Pressure gradients in this range cannot be expected to affect tissue perfusion significantly and independently generate compartment syndromes. These results do not confirm those of previous studies carried out by uncontrolled and unmonitored injections made by hand.

Injection studies in cadaver limbs can give dramatically different results depending upon the assumptions made when designing the experiment. The technique cannot adequately act as a model of the physiology of the compartment syndrome. As the existence of a physiologically significant compartmental boundary between flexor digitorum brevis and quadratus plantae is based solely on a cadaver infusion experiment the presence of a ‘calcaneal’ compartment has not been confirmed.

The results of a cadaver dye-infusion experiment suggested that the hand has ten muscle compartments and that the volar interossei occupy a separate anatomical compartment from the adjacent dorsal interossei. This is not supported by clinical findings. With various minor modifications, we repeated the experiment, infusing Omnipaque into the second dorsal interosseus muscle of four cadaver hands. We used real-time CT imaging to monitor the spread of contrast medium and side-ported needles to measure compartmental pressures. In all four hands, the tissue barrier between dorsal and volar interossei became incompetent at pressures of less than 15 mmHg.

Our data indicate that, although cadaver infusion studies can delineate potentially significant musculoskeletal barriers, their physiological relevance must be confirmed clinically.