The compartments of the foot revisited. Rethinking the validity of cadaver infusion experiments.

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.

Compartmental divisions of the hand revisited. Rethinking the validity of cadaver infusion experiments.

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.

Longitudinal tibial stress fractures: a report of eight cases and review of the literature.

PURPOSE: We present the imaging features of longitudinal stress fractures in eight patients and evaluate the literature to determine which tests are most useful for making this diagnosis. METHOD: Three musculoskeletal radiologists retrospectively reviewed eight cases of longitudinal tibial stress fractures presenting between 1988 and 1994. Reports on 36 cases, cited in the literature between 1960 and 1996, also were reviewed. Imaging modalities used and characteristic imaging features were noted. RESULTS: Plain radiographs had a characteristic appearance in approximately 28% of patients. Initially, plain films were negative, and in most cases, they eventually showed characteristic radiographic features. However, 25% of cases failed to demonstrate a plain film abnormality, with the diagnosis made by other modalities. CT or MRI is often diagnostic, and longitudinal stress fractures have characteristic imaging features with each modality. While sensitive, bone scan has lower specificity than either CT or MRI. CONCLUSION: Longitudinal stress fractures have characteristic imaging features, and familiarity with these features is necessary for timely and efficient diagnosis, avoiding morbidity due to delay or use of unnecessary tests.

Pitfalls in the radiologic evaluation of extremity trauma: Part II. The lower extremity.

Fractures of the lower extremity are common reasons for visits to family physicians. Some lower extremity fractures are especially likely to be missed. Examples of lesions that commonly go unrecognized include sacral insufficiency or fatigue fracture, fracture of the femoral neck (especially if the fracture is nondisplaced and/or impacted), tibial plateau fracture, Segond fracture (vertical fracture of the lateral tibia), patellar fracture, calcaneal fracture of the foot, Lisfranc fracture/dislocation of the tarsometatarsal apparatus, and Jones fracture of the fifth metatarsal. Lower extremity fracture in children may suggest the possibility of child abuse, especially in the case of multiple or bilateral fractures.

Pitfalls in the radiologic evaluation of extremity trauma: Part I. The upper extremity.

Family physicians often are required to evaluate patients who present with acute skeletal trauma. The first of this two-part series discusses the features and evaluation of some commonly missed fractures and dislocations of the upper limb, excluding the hand. Dislocations of the sternoclavicular joint are infrequent and often missed. Clavicular fractures in adults usually are not hard to diagnose. Acromioclavicular joint dislocations represent about 10 percent of all dislocation injuries to the shoulder girdle. Forty percent of all dislocations occur at the glenohumeral joint. Scapular fractures are often a result of significant force. Multiple views should be obtained in adults with a suspected fracture of the elbow. Complications in fractures of the wrist are strongly related to the location of the fracture.