Magnetic resonance and cadaveric findings of the "watershed band" of the achilles tendon

A review of 63 magnetic resonance images of 86 ankles was performed. (There were 23 bilateral studies.) A contiguous fascial band from the deep posterior compartment to the Achilles tendon watershed region was noted in 83 ankles. This fascial band enveloped the watershed region, coursing from the flexor (lacinate) ligament medially, to the peroneal retinaculum laterally. This band was absent in three patients who were scanned, two of whom sustained a complete Achilles tendon rupture, while the third had previously undergone peritenolysis. Forty cadaveric specimens with no known Achilles tendon pathology were evaluated for presence of this structure. An organized fascial band existed in all of these specimens. This previously undescribed structure is termed the "watershed band" and may have surgical significance.

Magnetic resonance and cadaveric findings of the incidence of plantaris tendon

A retrospective review of 63 Magnetic Resonance Image studies (yielding 86 ankles) was conducted to find the incidence of the plantaris tendon. Radiographically, the plantaris tendon was visualized 62.8% of the time. Surgical confirmation of this tendon during 18 achilles surgeries yielded 13 "true positives" and 4 "true negatives". Sensitivity was 92.8%; specificity and positive predictive value was 100%, respectively. As a comparison, forty cadaveric specimens were evaluated as well, with the incidence of the plantaris found to be 97.5%. These findings may be useful when considering MRIs as a screening tool for the presence of plantaris tendon. When axial images were 4 mm or less, the plantaris tendon was more easily visualized. A Chi-squared test examining for differences of axial sections greater than 4 mm was not significant. (P=0.2). This is important if one is to use MRI to screen for the plantaris (for graft purposes).

The relationship between articular cartilage degeneration and bone changes of the first metatarsophalangeal joint

Plain-film radiography is commonly used in the assessment of joints affected by osteoarthritis. It has been shown that the condition of articular cartilage in the knee, when grossly assessed, does not always correlate well to the radiographic evaluation of the joint. The aim of this study was to determine whether a relationship existed between the radiographic appearance of the subchondral bone and the morphological condition of the articular cartilage surfaces of the first metatarsophalangeal joint. Forty-nine pairs of cadaveric metatarsals and their respective proximal phalanges were studied in order to determine the correlation between articular cartilage degeneration and radiographic grade using a modified Kellgren-Lawrence scale. The relationship between cartilage degeneration and age, gender, osteophytes, metatarsal length, and measured angles (proximal articular set angle, distal articular set angle, intermetatarsal angle) was also investigated. It was found that there was a significant correlation between radiographic grade and cartilage degeneration on both the metatarsal head and the base of the proximal phalange (r2 = .2038 and .1733, respectively). However, while useful in the clinical setting, bony changes of the first metatarsophalangeal joint, as seen radiographically, fail to provide a full representation of the level of cartilage degeneration on the articular surfaces of this joint.

A densitometric analysis of the human first metatarsal bone

Bone responds to the stresses placed on it by remodeling its structure, which includes shape, trabecular distribution and density distribution. We studied 49 pairs of cadaveric human 1st metatarsal bones in an attempt to establish the pattern of density distribution and to correlate it with the biomechanical function of the bone. We found that the head is denser than the base, the dorsal portion of the whole metatarsal is denser than the plantar portion and the lateral portion of the whole metatarsal is denser than the medial aspect. The same pattern of density with respect to dorsal vs plantar and lateral vs medial was also seen in the head when it was examined alone. When we compared the 4 portions of the head with the same portion of the metatarsal as a whole we found that only the medial portion of the head was less dense than its respective portion of the whole metatarsal. All of these patterns of density distribution are consistent with respect to age, sex and laterality. We have also hypothesised as to the relationship between density distribution seen both in the whole metatarsal and in the metatarsal head and their biomechanical function in the gait cycle.

Relationship between articular cartilage damage and bone density in the first metatarsal

It is well known that bone changes occur in relationship to the articular cartilage damage seen in osteoarthritis. Numerous studies have shown a relationship between bone density and articular cartilage damage in knee and hip joints, but it is controversial as to whether or not an increased subchondral bone density results in greater cartilage damage. We studied 49 pairs of cadaveric first metatarsals in an attempt to correlate the level of cartilage damage seen on the distal articular surface with areal and volumetric density and other parameters such as bone geometry. A positive correlation was detected between articular cartilage damage and bone density by peripheral quantitative computed tomography in five of eight frontal slices in the head of the left metatarsal in the male sample only. The more extensive subchondral cysts found in the right male metatarsal may have contributed to the lack of correlation between the two variables on the right side. In addition, females displayed significantly greater osteophytosis than males at a given grade of cartilage damage, thus, possibly leading to a painful, apropulsive gait and a disuse osteopenia which would neutralize any subchondral bone density increase associated with cartilage damage. Microscopic investigations are, therefore, warranted to detect bone changes on a more discreet level, particularly within the subchondral plate.

Prevalence of degenerative morphological changes in the joints of the lower extremity

Information on the prevalence and extent of degenerative morphological changes (DMC) in the joints of the lower extremity, including foot joints is sparse. In the present study, the first and fifth metatarsalphalangeal (MTP), transverse tarsal, subtalar, talocrural, knee and hip joints of 50 cadavers were examined grossly and graded on a five-point scale for signs of DMC. Selected samples were examined histologically. Our results confirm clinical findings that severe DMC in foot joints are uncommon except in the first MTP joint where the plantar aspect is most affected. The knee joint displayed the most numerous and severe signs of DMC followed by the first MTP joint. The hip, talocrural, subtalar and transverse tarsal joints displayed comparatively moderate levels of DMC while the fifth MTP was rarely affected. The only joint to display significantly greater levels of DMC on the distal side of the joint as compared with the proximal side, when a difference was present, was the hip. There were significantly greater levels of DMC on the medial aspect of two or more joints within an extremity than on the lateral aspect. Radiographs often showed few or no signs of DMC even when erosion down to subchondral bone was observed upon gross examination.

Prenatal development of the foot and ankle

The general development of the lower limb and the specific development of the foot and ankle are discussed for each horizon in the embryonic and fetal periods of development. Lower limb general development is discussed only to the extent necessary for the understanding of foot and ankle development.