[On the development of the theory of flatfoot and the practice of the therapy of flatfoot].
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BACKGROUND: A flatfoot deformity alters the contact characteristics of the ankle joint, shifting the location of articulation posterolaterally, increasing pressure, and decreasing the contact area within the ankle. These changes may explain the pattern of articular degeneration and subsequent angulation observed in a long-standing adult acquired flatfoot. Corrective orthoses and surgical reconstruction have been used to realign pes planovalgus feet, but the effects of these treatments on tibiotalar contact characteristics are unknown. We hypothesized that realignment of a flatfoot with either corrective orthosis or surgical reconstruction would restore the contact characteristics of the ankle to the intact state. METHODS: The mean value of the contact area, contact pressure, peak contact pressure, and the relative locations of the global contact area and peak pressure within the ankle joint were determined from imprints created on pressure sensitive film for a series of cadaver lower limbs subjected to a weightbearing load in simulated midstance phase of gait. Each limb was loaded sequentially under four conditions: intact, flatfoot, flatfoot realigned with UCBL orthosis, and flatfoot realigned with a medial translational osteotomy of the calcaneus. RESULTS: The use of the UCBL orthosis and calcaneal osteotomy altered the contact characteristics of the ankle when compared with the flatfoot condition. Both interventions significantly decreased the mean global contact pressure from the flatfoot value, with the orthosis, demonstrating a significantly greater correction than the osteotomy. The orthosis also significantly reduced the peak contact pressure from the flatfoot value. Both interventions significantly corrected the lateral shift of the center of the peak contact pressure from the flatfoot value. The shift in the center of the global contact area approached significance when the orthosis was compared with the flatfoot. CONCLUSIONS: The changes observed in the magnitude and location of the mean and peak pressures indicate that the UCBL orthosis and calcaneal osteotomy altered hindfoot alignment to significantly influence tibiotalar contact characteristics. The results further suggest that the UCBL orthosis corrected ankle malalignment better than the calcaneal osteotomy in an adult acquired flatfoot. This study provides biomechanical data to support the clinical impression that realignment of the hindfoot corrects the pathologic tibiotalar contact characteristics associated with an adult acquired flatfoot. The results support the conclusion that the clinical management of a pes planovalgus foot with a UCBL orthosis or a medial translational osteotomy of the calcaneus may avert the onset of pantalar disease seen with late-stage posterior tibial tendon dysfunction.
BACKGROUND: Acquired flexible flatfoot encompasses a wide spectrum of disease, and there is no validated treatment protocol. We hypothesized that a medializing calcaneal osteotomy with a flexor digitorum longus transfer is adequate to correct a less severe acquired flexible flatfoot but not a more severe flatfoot. We also hypothesized that use of an additional procedure would further correct the flatfoot. METHODS: The study included seven pairs of cadaver specimens, with one side randomly selected for the creation of a mild flatfoot deformity and the other, for the creation of a severe flatfoot deformity. Cyclic axial load was applied to the intact foot, to the flatfoot, after correction with a medializing calcaneal osteotomy and a flexor digitorum longus transfer, and after the addition of a subtalar arthroereisis. Radiographic and pedobarographic data were obtained at each stage. A repeated-measures analysis of variance with post hoc analysis was used to compare all parameters in the intact foot with those in the flatfoot and corrected specimens. A Student t test was used to compare flatfoot severity between the mild and severe models. RESULTS: Compared with the intact foot, the mild and severe flatfoot models showed a significant change in the talar-first metatarsal angle (p = 0.01 and 0.03, respectively), talonavicular angle (p = 0.04 and 0.04), and medial cuneiform height (p = 0.03 and 0.05). The mild and severe models were significantly different from each other with regard to the talar-first metatarsal angle (p = 0.003) and talonavicular angle (p = 0.002). After the osteotomy and tendon transfer in the mild-flatfoot model, the talar-first metatarsal angle and talonavicular angle were not significantly different from those in the intact state. In the severe-flatfoot model, the talar-first metatarsal angle, talonavicular angle, and medial cuneiform height remained significantly undercorrected after the osteotomy and tendon transfer. After the arthroereisis, the talonavicular angle and medial cuneiform height were not significantly different from the values for the intact foot. CONCLUSIONS: In a cadaver model, the effectiveness of different procedures on radiographic and pedobarographic parameters varies with the severity of an acquired flatfoot deformity.
HYPOTHESES/PURPOSE: The success of the medial displacement calcaneal osteotomy in correcting flatfoot deformities is likely to be the result of a shift of the Achilles tendon forces on the hindfoot. The purpose of this study was twofold: 1) to define the contribution of the Achilles tendon to the flatfoot deformity, and 2) to define the effect of a calcaneal medial displacement osteotomy. METHODS: We used six different experimental dynamic stages: 1) intact foot without Achilles loading; 2) intact foot with Achilles loading; 3) flatfoot without medial calcaneal displacement osteotomy and without Achilles loading; 4) flatfoot without medial calcaneal displacement osteotomy but with Achilles loading; 5) flatfoot with medial calcaneal displacement osteotomy but without Achilles loading; and 6) flatfoot with medial calcaneal displacement osteotomy and with Achilles loading. The experimental flaffoot was developed by releasing the posterior tibial tendon, spring ligament, and plantar fascia and applying 7,000 cycles of axial fatigue load (range, 700 to 1,400 N; 1-Hz frequency). To simulate the phase of midstance, the peroneus longus, peroneus brevis, flexor digitorum longus, and flexor hallucis longus tendons were grasped by clamps, connected to pneumatic actuators, and loaded with precalculated forces. Anteroposterior and lateral radiographs were obtained for each stage on which the following measurements were made: talonavicular coverage angle, talar-first metatarsal angle, talocalcaneal angle, and height of the medial cuneiform. These measurements were compared with a one-way ANOVA. RESULTS: Between stages 1 and 2, all measurements were statistically insignificant. Between stages 3 and 4, for all measurements, Achilles tendon loading aggravated the flatfoot deformity (p < 0.05). After medial calcaneal osteotomy (stages 5 and 6), the Achilles tendon contributed less to the arch-flattening. We found that the medial displacement osteotomy plays an important role in reducing and/or delaying the progress of flatfoot deformity. CONCLUSIONS/SIGNIFICANCE: In the flatfoot, loading of the Achilles tendon increases the deformity. Medial calcaneal osteotomy significantly decreases the arch-flattening effect of this tendon and therefore limits the potential increase of the deformity.
This study quantified and compared the efficacy of in-shoe orthoses and ankle braces in stabilizing the hindfoot and medial longitudinal arch in a cadaveric model of acquired flexible flatfoot deformity. This was addressed by combining measurement of hindfoot and arch kinematics with plantar pressure distribution, produced in response to axial loads simulating quiet standing. Experiments were conducted on six fresh-frozen cadaveric lower limbs. Three conditions were tested: intact-unbraced; flatfoot-unbraced; and flatfoot-braced. Flatfoot deformity was created by sectioning the main support structures of the medial longitudinal arch. Six different braces were tested including two in-shoe orthoses, three ankle braces and one molded ankle-foot orthosis. Our model of flexible flatfoot deformity caused the calcaneus to evert, the talus to plantarflex and the height of the talus and medial cuneiform to decrease. Flexible flatfoot deformity caused a pattern of medial shift in plantar pressure distribution, but minimal change in the location of the center of pressure. Furthermore, in-shoe orthoses stabilized both the hindfoot and the medial longitudinal arch, while ankle braces did not. Semi-rigid foot and ankle orthoses acted to stabilize the medial longitudinal arch. Based on these results, it was concluded that treatment of flatfoot deformity should at least include use of in-shoe orthoses to partially restore the arch and stabilize the hindfoot.
In the flexible pes planovalgus deformity of stage 2 posterior tibial tendon dysfunction, osteotomies appear to have a significant role in operative management by restoring more normal biomechanics, allowing tendon transfers to function successfully. The options when considering osteotomies for stage 2 disease include lateral column lengthening, medial displacement calcaneal osteotomy, and combined double osteotomy technique. The tight Achilles tendon should be lengthened as well. Lateral column lengthening has been used extensively for treatment of flexible flatfeet. It has been shown clinically and radiographically to address all 3 components of the pes planovalgus deformity present in stage 2 posterior tibial tendon dysfunction. Lateral column lengthening is used in combination with a medial soft tissue rebalancing procedure. The mechanism of action is still speculative but clearly is not owing to tensioning of the plantar fascia as previously thought. Despite the excellent correction of foot posture obtained by use of lateral column lengthening for adult acquired flatfoot, many clinicians have reservations about its use because of reported secondary increases in the calcaneocuboid joint pressures. This increase in pressure has been shown to occur experimentally, increasing the potential risk of calcaneocuboid joint arthrosis. This experimental evidence is supported by Phillips' study of the original Evans procedure, which resulted in a 65% incidence of calcaneocuboid joint arthrosis at 13-year follow-up. Mosier-LaClair et al reported a 14% incidence of calcaneocuboid joint arthritis at 5-year follow-up after double osteotomy for stage 2 posterior tibial tendon dysfunction. This incidence has not been proved true in the remainder of the literature surrounding this procedure and its use for flexible flatfoot. To address the concern regarding potential calcaneocuboid arthrosis secondary to lateral column lengthening, calcaneocuboid joint distraction arthrodesis has been explored as an alternative technique. The results show good initial correction, but the follow-up is extremely limited, and one study reported loss of correction over time. Longer follow-up is needed to determine whether or not this technique would provide the lasting correction seen with the Evans procedure. Calcaneocuboid joint lengthening arthrodesis does result in some limitation of adjacent hindfoot motion. Although this limitation is significantly less compared with talonavicular and subtalar joint fusion, this procedure may result in increased local pressures and arthrosis of the midfoot or hindfoot. For the above-mentioned reasons, longer follow-up studies are needed to determine whether calcaneocuboid joint distraction arthrodesis would prove to be a reliable and safe alternative for lateral column lengthening in the treatment of adult acquired flatfoot. Medial displacement calcaneal osteotomy has been used for correction of the pes planovalgus foot in posterior tibial tendon dysfunction. It has been used extensively for the surgical treatment of flexible flatfoot throughout the literature. Medial displacement osteotomy, in combination with flexor digitorum longus tendon transfer, can address all 3 components of adult acquired flatfoot. It does not recreate the medial longitudinal arch in all patients, however. Although the mechanism of action of medial displacement calcaneal osteotomy is unknown, it has been proved that it is not through the tightening of the plantar fascia in a windlass effect as previously thought. In contrast to lateral column lengthening, however, medial displacement calcaneal osteotomy does address the deforming valgus force of the Achilles tendon. Functionally transferring the insertion of the Achilles tendon medially removes a constant valgus-deforming force. The osteotomy can then act as a double tendon transfer with the flexor digitorum longus tendon to aid in foot inversion. For stage 2 posterior tibial tendon insufficiency, the authors favor the combination double osteotomy technique with a flexor digitorum longus tendon-to-medial cuneiform tendon transfer, débridement or removal of the posterior tibial tendon, and percutaneous heel cord lengthening. Early results were positive at 1.5 years after surgery with respect to maintenance of correction and functional improvement with no evidence of calcaneocuboid arthrosis. More recently, the intermediate 5-year follow-up has been assessed for this combination of procedures, and similar results were found. There was a high rate of patient satisfaction and functional improvement, and surgical correction of the flatfoot deformity was maintained and compared favorably with the contralateral normal foot. Although the intermediate follow-up found a 14% incidence of calcaneocuboid arthrosis, 50% of these patients had preoperative evidence of calcaneocuboid joint arthritis. (ABSTRACT TRUNCATED)
OBJECTIVE: To test in cadaveric feet the hypothesis that prefabricated foot orthoses will improve arch alignment in flatfoot deformity. DESIGN: Experimental, paired comparisons. SETTING: Biomechanics laboratory. CADAVERS: Nine cadaveric lower-extremity specimens with no abnormalities. INTERVENTIONS: To evaluate the performance of 2 orthoses specimens were tested in 4 combinations: intact, flatfoot, flatfoot with shoe and orthosis 1, and flatfoot with shoe and orthosis 2. To simulate the midstance phase of gait, loads were applied to 5 tendons and an axial load equivalent to two thirds of the standing load was applied to the foot's plantar surface. MAIN OUTCOME MEASURES: Arch height and tarsal bone positions before and after a flatfoot deformity created by ligament sectioning; tarsal bone positions determined with a magnetic tracking system. RESULTS: After ligament sectioning, the average decrease in arch height with a shoe applied was 4.6+/-1.6mm (8%); with orthosis 1, mean arch height increased 0.7+/-0.6mm (P=.008); with orthosis 2, it increased 0.3+/-0.5mm (P=.05). With both orthoses, arch height after sectioning was significantly less than that of the normal arch. Compared with the flatfoot condition, metatarsal-talar alignment improved in plantar flexion and inversion with both orthoses but did not approximate normal with either orthosis. Calcaneal-tibial position did not improve with either orthosis and was markedly different from that in the intact foot with either orthosis. No difference was found between the 2 orthoses except for metatarsal-talar motion in external rotation (P=.014) and eversion (P=.026). CONCLUSIONS: Arch alignment improved significantly but to a limited degree (<2%) in cadaveric feet with the use of orthoses. Hindfoot valgus malalignment did not consistently improve by the use of shoe inserts.
Arthrodesis of the subtalar joint is well recognized treatment option for moderate or severe flatfoot associated with adult acquired flatfoot secondary to posterior tibial tendon dysfunction. The success of the subtalar arthrodesis is dependent on restoration of normal bony relationships in the hindfoot and midfoot. For this reason, a distinction is made between a repositional arthrodesis and the traditional in situ type of arthrodesis. An in vitro study of the adult acquired flatfoot identifies an anteroposterior subluxation of the subtalar articulation that can be corrected durably and reliably through a repositional talocalcaneal arthrodesis. Intraoperative reduction techniques are useful in obtaining reduction of the peritalar subluxation. There are certain clinical features that help identify patients with flatfoot deformities who are good candidates for subtalar fusion. As the pathoanatomy of the flatfoot deformity is better elucidated, treatment techniques are modified to better address the key elements of the deformity. A repositional subtalar arthrodesis was shown to produce excellent correction in a moderate to severe in vitro flatfoot example in the authors' clinical series.
BACKGROUND: When flatfoot is acquired during adulthood, the shape of the foot changes. In addition to a decreased arch, there may be valgus angulation of the hindfoot or abduction of the forefoot, or both. However, there is little objective information to provide a better understanding of the anatomical or morphological changes that occur in acquired adult flatfoot. We wondered if such an understanding of the three-dimensional anatomy might shed light on the pathway by which these changes occur. We designed this study to measure the three-dimensional position of the talocalcaneal joint in patients who have painful flatfoot. METHODS: Computed tomography scans of the feet of eight patients who had symptomatic flatfoot were used to construct a model of the talocalcaneal articulation. The scans were performed on a custom loading frame developed to simulate weight-bearing with the foot in a neutral position while a seventy-five-newton axial compressive load was applied. The digital data from the scans were used to make three-dimensional computer models of the articular surfaces of the talus and calcaneus of each foot. These models then were used to calculate the percentage of the articular surface that was in contact and, conversely, the percentage that was subluxated. Two surfaces were modeled for each bone; the posterior facet formed one surface, and the anterior and middle facets were combined to form the second surface. The data were compared, with use of Mann-Whitney nonparametric U analysis, with those derived from scans of the feet of four patients without a deformity of the hindfoot who served as controls. RESULTS: A mean (and standard deviation) of 68+/-9 percent of the posterior facet of the calcaneus was in contact with the talus in the patients who had flatfoot compared with 92+/-2 percent in the controls, and a mean of 51+/-23 percent of the anterior and middle facets of the calcaneus was in contact with the talus in the patients who had flatfoot compared with 95+/-6 percent in the controls. These differences were significant (p = 0.0066 for both). CONCLUSIONS: Marked subluxation of the talocalcaneal joint occurs in some patients who have symptomatic planoabductovalgus deformity.