Ewing's sarcoma of the foot

The results of treatment were reviewed in 16 patients (10 male and six female) who had Ewing's sarcoma of the foot from 1954 through 1992. Mean age was 17 years (range, 10-42 years). The tumor involved the metatarsals (six patients), phalanges (four), calcaneus (three), navicular (one), talus (one), and calcaneus and phalanx (one). Seven patients had metastatic disease at the time of diagnosis, and only one of these patients survived. None of the patients with pulmonary metastasis at presentation survived. Nine patients had localized disease at the time of diagnosis, and eight survived. In the overall series, nine of the 16 patients were alive at followup (eight survived at least 5 years). Diagnosis was established at an average of 14 months from the onset of symptoms: 7 months in forefoot tumors and 22 months in hindfoot tumors. None of the six patients who had a resection had local failure. Seven of the 10 patients with forefoot lesions survived, and two of the six patients with hindfoot lesions survived. Treatment of Ewing's sarcoma of the foot by local control with radiation or operation and systemic control with chemotherapy is recommended. Survival appears to be better in patients who present with localized disease and forefoot lesions. Survival is worse in patients who present with metastatic disease. Surgical treatment appears to have an important role in local control and survival.

Subtalar joint stability. Talocalcaneal interosseous ligament function studied in cadaver specimens

We used 6 fresh-frozen foot specimens to evaluate the contribution of the talocalcaneal interosseous ligament (IOL) in stabilizing the subtalar (talocalcaneal) joint. The tibia and ankle joint were secured, and the calcaneus was subjected to a bending and axial force applied circumferentially. The position of the calcaneus relative to the talus was monitored with a magnetic tracking system. Motion was recorded at every half degree in the 0 degree to 360 degrees arc before and after sectioning of the IOL. The results in the intact feet indicated that, with circumferential loading of the subtalar joint, there were two stable zones (supination stable zone, pronation stable zone) during which little displacement occurred and two transition zones during which the supination and pronation movement occurred. There was a greater degree of supination displacement after IOL sectioning (p = 0.008), but no pronation displacement. The IOL contributed substantially to subtalar joint stability, particularly in supination.

Quantitative analysis of the intrinsic muscles of the foot

BACKGROUND

Understanding muscle architecture of the foot may assist in the design of surgical procedures such as tendon transfer, biomechanical modeling of the foot, prosthesis design, and analysis of foot function. There is limited published information regarding foot intrinsic muscle architecture.

METHODS

Eleven fresh-frozen cadaveric feet were studied from eight males and three females. Twenty-eight intrinsic muscles were dissected in each foot, and measurements of fiber length, muscle length, and muscle volume obtained using calipers and water displacement technique. The physiologic cross-sectional area, fiber/muscle length ratio, muscle mass fraction, and tension fraction were then calculated.

RESULTS

Intrinsic muscle length was related to foot size. The mean fiber length ranged from 13.6 mm (first plantar interosseous) to 28.0 mm (second extensor digitorum brevis). The mean muscle length ranged from 24.8 mm (adductor hallucis transverse) to 115.8 mm (abductor hallucis). The mean muscle volume ranged from 0.4 cc (fifth lumbrical) to 15.2 cc (abductor hallucis). The physiologic cross-sectional area ranged from 0.28 cm2 (second and third lumbrical) to 6.68 cm2 (abductor hallucis). The fiber/ muscle ratio ranged from 0.20 (abductor hallucis) to 0.82 (adductor hallucis transverse). The mass fraction ranged from 0.33% (fifth lumbrical) to 16.59% (abductor hallucis). The tension fraction ranged from 0.34% (fifth lumbrical) to 15.37% (abductor hallucis).

CONCLUSIONS

The abductor hallucis and adductor hallucis oblique had much greater physiologic cross-sectional areas compared to those of the other intrinsic muscles. The lumbrical muscles had relatively low physiologic cross-sectional areas. These observations illustrate the underlying structural basis for the functional capacities of the intrinsic muscles of the foot.

Analysis of longitudinal arch supports in stabilizing the arch of the foot

Two orthotic devices commonly prescribed as arch supports were studied to evaluate their efficacy in stabilizing the foot. Fourteen cadaveric feet were mounted in a loading frame, and an axial load of 222, 445, or 667 N was applied while three-dimensional positions of the talus, calcaneus, navicular, and first metatarsal were monitored with a magnetic tracking system. Feet were tested with and without the use of two commonly prescribed arch supports. The two indices used to assess arch stabilization were arch height and joint rotation. Joint rotations consistently increased on load application. Significant differences were observed with Inserts 1 and 2 in metatarsal talar abduction, dorsiflexion and eversion, calcaneal talar eversion, and talar tibial dorsiflexion. Arch height significantly increased with both inserts. Contrary to previously published results, the arch supports that were studied provided measurable improvement in arch stability in a simulated standing at ease position.

Analysis of clinical grading scales for the foot and ankle

To evaluate grading methods used to report clinical results, we reviewed 1,607 articles related to the foot and ankle published in six orthopaedic journals from 1980 through July 1993. Many clinical studies use criteria such as patient satisfaction to grade results. A numeric score or grade was used in 346 articles: 238 used a grade only, 90 used a numeric score and grade, and 18 used a numeric score only. The numeric score or grade was usually, but not always, reported with details of the individual clinical factors that composed the score or grade. Twenty-three articles used a score before and after treatment. Statistics were used in 62 articles, and in 6 of those the statistics were used to compare clinical condition before and after treatment. This study demonstrated the array of grading methods used in selected orthopaedic journals and indicated the need for standardized grading techniques to allow for more meaningful interpretation of the orthopaedic literature.

Physiological elongation of ligamentous complex surrounding the hindfoot joints: in vitro biomechanical study

Ligaments surrounding the hindfoot joints play an important role in hindfoot stability. This in vitro study investigated anatomical and biomechanical characteristics of nine major ligamentous structures, including length and orientation at neutral position and physiological elongation with the foot in five different positions relative to the neutral position. The results showed that ligament elongation depended on the ligament length, orientation in neutral position, and movement of bones to which they were attached.

Gait abnormalities following resection of talocalcaneal coalition

Eleven patients (fourteen feet) had resection of a coalition of the middle facet of the talocalcaneal joint because of symptoms that had been present for a mean of four years (range, 0.5 to nine years). The mean age at the time of the resection was seventeen years (range, thirteen to thirty-two years). Nine patients were male and two were female. Five feet had resection of the bone bridge with interposition of fat or tendon, and nine had resection without any interposed material. The mean duration of follow-up was six years (range, two to thirteen years). The clinical result was excellent for five feet, good for four, fair for three, and poor for two. Inversion was 8 +/- 4.5 degrees (mean and standard deviation) on the involved side and 17 +/- 6.2 degrees on the uninvolved side (p = 0.002). Three feet later had evidence of osteoarthrosis of the subtalar joint. Gait analysis demonstrated decreased motion of the hindfoot and the ankle, compared with that in normal subjects and with that in the contralateral (uninvolved) foot, in the sagittal and coronal planes during walking on a level surface. Motion was also reduced, particularly in the sagittal and coronal planes, during walking on a side slope. Ground-reaction forces (F8 and F9), temporal force factors (T2, T3, and T7), and the percentage of the gait cycle that consisted of the stance phase on the side-sloping walkway were different from those in normal subjects or in the uninvolved foot. These data indicate that, although most of our patients who had resection of a talocalcaneal coalition had a successful clinical result, most had a residual functional deficit.

Kinematics and contact characteristics of the first metatarsophalangeal joint

We studied six fresh frozen cadaver feet to define the three-dimensional motion of the hallux proximal phalanx in relation to the first metatarsal and to describe the contact features of the first metatarsophalangeal joint. Six tendons to the hallux were loaded to simulate dynamic loading of the hallux. A magnetic tracking system was used to monitor the three-dimensional movement of the proximal phalanx while the toe position was changed from a neutral position to full extension by adjusting the tendon loads. The average surface area was 0.38 +/- 0.08 cm2 in the neutral position; it decreased with toe extension and was the lowest (0.04 +/- 0.03 cm2) at the full extension position. Contact distribution of the proximal phalanx did not change substantially throughout the arc of motion. However, for the metatarsal articular surface, the contact distribution shifted dorsally with increasing degrees of extension. These data are consistent with the observation that chondral erosions associated with hallux rigidus and degenerative arthritis initially affect the dorsal articular surface of the metatarsal, and implant arthroplasty often fails from component loading dorsally. The current technique of determining joint contact characteristics is applicable not only for the first metatarsophalangeal joint but also other joints that have not been studied because of shortcomings with more conventional methods.

Three-dimensional analysis of normal ankle and foot mobility

We defined foot and ankle motion with respect to the neutral position. Thirteen normal fresh-frozen specimens of the human foot were used. The foot was placed in the extreme positions of pronation, supination, dorsiflexion, and plantar flexion, and positions of multiple bones were monitored simultaneously with a magnetic tracking device to determine rotation of the talocrural, subtalar, metatarsal-navicular, and talonavicular joints under the various conditions. In pronation, the most rotation occurred at the metatarsal-navicular level, followed by the navicular-talar, talar-tibial, and calcaneal-talar levels. In supination, most rotation occurred at the navicular-talar level, followed by the calcaneal-talar, talar-tibial, and metatarsal-navicular levels. In dorsiflexion, most rotation occurred at the talar-tibial level, followed by the navicular-talar, calcaneal-talar, and metatarsal-navicular levels. In plantar flexion, most rotation occurred at the talar-tibial level, but there was considerable motion at the navicular-talar, metatarsal-navicular, and calcaneal-talar levels. Understanding the specific joint motions that occur with various positions of the foot and ankle is important because measurements of joint mobility may assist in establishing diagnoses, monitoring clinical conditions, determining indications for operative treatment, assessing results of treatment, and following the progress of rehabilitation.

Mechanical behavior of the foot and ankle after plantar fascia release in the unstable foot

The change in position of the bones of the foot was studied in three dimensions after plantar fascia release in intact and destabilized feet. Fifteen fresh-frozen human foot specimens were used. Physiologic loads of 445 newtons were applied axially to simulate standing at ease, and the three-dimensional position of tarsal bones was determined with a magnetic tracking device. The positions were presented in the form of screw axis displacements, quantitating rotation, and axis of rotation orientation. After fasciotomy in the six intact feet, significant differences in rotation were observed at the talotibial and calcaneotalar levels. After fasciotomy in the four unstable feet with three supporting elements sectioned, significant differences in position were observed at the talotibial joint and a significant decrease in arch height was observed. After fasciotomy in the five unstable feet with five supporting elements sectioned, significant differences in rotation were observed at the talotibial joint (mean, 5.5 +/- 1.6 degrees; P = 0.001), calcaneotalar joint (mean, 6.1 +/- 2.1 degrees; P = 0.003), and metatarsotalar level (mean, 9.3 +/- 4.1 degrees; P = 0.007). The average decrease in arch height was 7.4 +/- 4.1 mm (P = 0.015). Displacement of all joints tested occurred after fasciotomy, with rotation about all three axes. These changes in displacement were more pronounced in unstable or destabilized feet. The data suggest that operations involving fasciotomy affect arch stability and should not be performed in patients with evidence of concomitant pes planus deformity, because of the likelihood of further deformation.

Effect of the posterior tibial tendon on the arch of the foot during simulated weightbearing: biomechanical analysis

A cadaver study was performed to determine the effect of the posterior tibial tendon (PTT) on the stability of the foot in simulated midstance phase of gait. Thirteen fresh-frozen human foot specimens were used. Loads were applied axially and to each tendon. Three-dimensional positions of tarsal bones before and after tendon loading were determined with the use of a magnetic tracking device. Significant differences in tarsal bone positions were observed with application of loads to the Achilles, posterior tibial, flexor digitorum longus, peroneus longus, and peroneus brevis tendons at the metatarsotalar, calcaneotalar, and talotibial joints and in overall arch height. These tendon loads caused position changes toward arch flattening or mild pes planus deformity. Significant differences in tarsal bone positions were observed with PTT loading compared with no PTT loading in metatarsotalar, calcaneotalar, and talotibial levels as well as arch height. The PTT caused position changes toward restoring the arch alignment. These data suggest that the PTT is an important stabilizer of the arch of the foot.

Clinical results of the Mayo total ankle arthroplasty

Two hundred and four primary Mayo total ankle arthroplasties were performed in 179 patients at the Mayo Clinic from 1974 through 1988. We evaluated the clinical result after 160 arthroplasties in 143 patients who had been followed for two years or more (mean, nine years; range, two to seventeen years). The result was good for thirty-one ankles (19 per cent), fair for fifty-five (34 per cent), and poor for seventeen (11 per cent); fifty-seven arthroplasties (36 per cent) were considered to be a failure (defined as removal of the implant). Adequate preoperative and follow-up radiographs were available for 101 ankles (eighty-nine patients). There was radiographic evidence of loosening of eight tibial components (8 per cent) and fifty-eight talar components (57 per cent), but we found no association between the clinical and radiographic results. Complications occurred after nineteen (12 per cent) of the 160 arthroplasties, and ninety-four additional reoperations were necessary after sixty-six (41 per cent). On the basis of these findings, we do not recommend ankle arthroplasty with a constrained Mayo implant for rheumatoid arthritis or osteoarthrosis of the ankle.

Nonoperative treatment of plantar interdigital neuroma with a single corticosteroid injection

Patients who received a single corticosteroid injection for treatment of third webspace plantar interdigital neuroma were studied retrospectively. Forty-three patients (51 feet) were available for followup study (followup mean, 4 years; range, 2 to 6 years). Mean age of patients was 53 years. Pain initially was relieved in 36 patients (41 feet [80%]). Twenty-four feet (47%) ultimately required surgical excision, while most of the remaining 27 feet (53%), which had not been treated surgically, were the source of residual symptoms in patients. A single corticosteroid injection cannot be recommended as a cure for symptoms of third webspace neuroma, but it can be offered as a temporizing measure or as nonoperative treatment. A single corticosteroid injection does not preclude a successful surgical result.

Contact features of the talonavicular joint of the foot

Seven cadaveric feet were studied to determine the distribution of the contact area of the talonavicular joint. Feet were loaded axially with soft tissue structures intact and after sectioning of static elements that support the arch. Bony displacement was monitored with a magnetic tracking device, and joint contact was determined from proximity calculations of digitized joint surfaces. With physiologic loading of the intact foot, the number of regions in contact increased. In the unstable foot, there was a shift in contact distribution toward more dorsal and central regions of the navicular bone. This is consistent with the clinical observation that fatigue fractures, acute fractures, and nonunion of navicular fractures occur often in the central navicular body. The alteration in contact characteristics in unstable feet is also consistent with the observation that osteoarthrosis of the hindfoot joints occurs commonly with long-standing arch instability or pes planus deformity.

Kinematics of the normal arch of the foot and ankle under physiologic loading

We studied 15 cadaver feet to determine three-dimensional motion of selected tarsal bones under axial loading at three different loading levels. We determined the motion of individual joints and also the rotation of the tarsal bones in relation to the tibia. Joint rotations increased consistently with higher loads. The naviculartalar joint had the greatest total screw axis rotation, which averaged 9.4 degrees +/- 2.2 degrees at 667 N of load, followed by the first metatarsal-navicular (mean, 7.2 degrees +/- 1.5 degrees), talartibial (mean, 5.2 degrees +/- 1.6 degrees), and calcaneal-talar (mean, 4.4 degrees +/- 1.7 degrees) joints. The observed changes indicate the need for assessment of foot and ankle alignment clinically and radiologically while the patient is weightbearing.

Late versus early repair of Achilles tendon rupture. Clinical and biomechanical evaluation

Eleven patients who had late reconstruction for Achilles tendon rupture were compared with 10 patients who had immediate repair. The followup period averaged 8 years for both groups. Results, based on a clinical score, were successful (excellent or good) for all but 1 patient. Although manual testing demonstrated normal plantar flexion strength in all but 1 patient, significant differences were seen in isometric and isokinetic plantar flexion strength of the involved sides as compared with the uninvolved sides of these patients. The patient with the unsuccessful result had abnormalities in vertical, foreaft, and medial-lateral force components of the ground reaction force. Three-dimensional motion analysis showed decreased total motion in the sagittal plane on the operated side as compared with the unoperated side in this patient. The data indicated that patients with late reconstruction of Achilles tendon rupture have successful clinical results comparable with those of early repair.

Shock-absorbing effect of shoe insert materials commonly used in management of lower extremity disorders

The efficacy of 3 shock-absorbing materials was compared by determining impact characteristics with a drop test method and also by testing the effect of each material when used as a shoe insert in 16 asymptomatic subjects. Peak vertical ground reaction force (F1, F2, F3) and temporal force factors (T1, T2, T3) were obtained with a force plate at a high-frequency sampling rate. Impact force, impact time, impact slope, and impact energy were determined. A standard weight was dropped from 3 heights on each material covering the force plate while reduction of peak force was compared. Impact force was attenuated most effectively by Insert 3 (polymeric foam rubber) and averaged 11% less than that in shoes without inserts. Impact time was increased for all 3 inserts. Impact slope and impact energy were reduced significantly in Insert 3. There was a significant difference in peak vertical force F1 for all 3 inserts, in vertical force F2 for Insert 2 (viscoelastic polymeric material), and in vertical force F3 for Insert 2. Drop-test studies showed that at all ball heights, the highest mean peak force was observed consistently in Insert 2.

Displaced intra-articular fractures of the calcaneus treated non-operatively. Clinical results and analysis of motion and ground-reaction and temporal forces

Twenty-seven patients who had a unilateral displaced intra-articular fracture of the calcaneus were managed with a cast instead of with reduction or an operation. The clinical result after a mean of six years (range, two to ten years) was excellent in five patients, good in five, fair in seven, and poor in ten. The sixteen patients who were re-examined for this study and for whom the gait was analyzed demonstrated abnormalities in ground-reaction force with regard to vertical force (F3) and temporal force factors (T2, T3, T6, and T9). Analysis of temporal and distance factors showed a trend toward a decreased proportion of single-limb support on the involved side. Three-dimensional motion analysis of the ankle and hindfoot was performed with electrogoniometers as the subject walked on a level surface, on a 10-degree side-slope, and up and down stairs. Motion was decreased in the sagittal, coronal, and transverse planes during walking on level ground and on a side-sloping surface. Significant decreases in motion in these planes were also seen during walking up and down stairs. Although these patients did not have a subsequent reconstructive operation, most had a residual functional deficit.

Material properties of the plantar aponeurosis

Material properties of the plantar aponeurosis were determined by a two-dimensional video tracking method to simultaneously measure the aponeurosis deformation. Failure loads averaged 1189 +/- 244 N and were higher in men. Average stiffness of the intact fascia was 203.7 +/- 50.5 N/mm at a loading rate of 11.12 N/sec and it did not vary significantly for the loading rates of 11.12 to 1112 N/sec. The high tensile loads required for failure were consistent with clinical and biomechanical studies and indicated the importance of the aponeurosis in foot function and arch stability.

Survivorship analysis of the Mayo total ankle arthroplasty

From 1974 until the end of 1988, 204 primary Mayo total ankle arthroplasties were performed at the Mayo Clinic. By means of actuarial analysis, we determined the cumulative rates of survival with failure (defined as removal of the implant) as the end point. The average duration of follow-up was nine years (range, two to seventeen years). By applying the Cox proportional-hazards general linear model, we identified two independent variables that were associated with a significantly higher risk of failure: a previous operative procedure on the ipsilateral foot or ankle and an age of fifty-seven years or less. The overall cumulative rate of survival at five, ten, and fifteen years was 79, 65, and 61 per cent, respectively. The probability of an implant being in situ at ten years was 42 per cent for patients who were fifty-seven years old or less and who had had previous operative treatment of the ipsilateral ankle or foot and 73 per cent for those who were more than fifty-seven years old and who had had no such previous operative treatment. We do not recommend the use of the Mayo total ankle arthroplasty, particularly in younger patients who have had a previous operative procedure on the ipsilateral ankle or foot.

Clinical rating systems for the ankle-hindfoot, midfoot, hallux, and lesser toes

Four rating systems were developed by the American Orthopaedic Foot and Ankle Society to provide a standard method of reporting clinical status of the ankle and foot. The systems incorporate both subjective and objective factors into numerical scales to describe function, alignment, and pain.

Survivorship analysis of implant arthroplasty for the first metatarsophalangeal joint

During a 21-year period at the authors' institution, 93 primary implants of the first metatarsophalangeal joint were performed on 79 patients (12 men and 67 women). Their mean age was 56 years (range, 19 to 75 years). The average duration of follow-up evaluation in 75 patients who were alive and without reoperation was 12 years (range, two to 17 years). With the proportional hazards general linear model, young age was identified as a significant risk factor for poor survival: at ten years, implant survival was 82% in patients 57 years of age or younger, and 90% in patients older than 57 years. The overall probability that an implant would not have been removed was 86% at ten years after arthroplasty and 82% at 15 years.