Faculty Bibliography

BACKGROUND:Lateral column lengthening has been associated with residual forefoot supination and symptomatic lateral overload in treatment of acquired flatfoot. A medial column procedure may be useful to redistribute load to the medial column. We evaluated radiographic and pressure changes in a severe flatfoot model with lateral column lengthening and investigated the effect of an added first metatarsocuneiform arthrodesis. METHODS:Ten cadaver specimens were loaded in simulated double-legged stance, and radiographic and pressure data were collected for all tested states. Calcaneocuboid arthrodesis was done with a 10-mm foam wedge. Residual forefoot varus was corrected through the first metatarsocuneiform joint. RESULTS:Differences in the mean lateral talar-first metatarsal angle, talonavicular angle, talocalcaneal angle, and calcaneal pitch were significant between the intact foot and the flatfoot. After calcaneocuboid distraction arthrodesis and tendon transfer, the lateral talar-first metatarsal angle, talonavicular angle, and calcaneal pitch were significantly different from the flatfoot. After added first metatarsocuneiform arthrodesis, the talonavicular angle was not significantly different from the intact foot. Lateral forefoot pressure increased in the flatfoot after lateral column lengthening but was not significantly different from the intact foot after first metarsocuneiform arthrodesis was added. CONCLUSIONS:Adding first metatarsocuneiform arthrodesis to calcaneocuboid distraction arthrodesis for treatment of flatfoot deformity provided improvement in radiographic and pedobarographic parameters of a severe model of stage II posterior tibial tendon dysfunction.

BACKGROUND:The purpose of this study was to identify subtypes of atraumatic osteoarthritis of the tarsometatarsal joints based on accompanying foot deformities and to determine whether concurrent procedures done for each subtype were effective. METHODS:The study included 59 patients (67 feet) with atraumatic tarsometatarsal joint osteoarthritis treated with tarsometatarsal fusion. The average patient age was 60.2 years with 40.6 months followup. Patients were evaluated with radiographs, the American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Scale, the Foot Function Index, and the Short Form-36 Health Survey Questionnaire (SF-36). RESULTS:Four main subtypes were identified based on associated foot deformities: pes planovalgus (27), hallux valgus (11), in-situ without deformities (eight), and rockerbottom (five). Plantar-medial closing-wedge resection was used to correct rockerbottom deformity. For pes planovalgus deformity, a medial sliding calcaneal osteotomy was done. Lateral column lengthening with medial sliding calcaneal osteotomy was done for tarsometatarsal osteoarthritis with severe pes planovalgus, and triple arthrodesis was done for rigid pes planovalgus. Tarsometatarsal osteoarthritis with hallux valgus deformity was corrected with the Lapidus procedure. There were 29 complications, most commonly sesamoid pain. The pes planovalgus group showed significant radiographic improvements in four of five parameters measured. AOFAS scores improved from retrospectively assigned preoperative 34.1 points to postoperative 83.9 points. The Foot Function Index showed a high satisfaction rate (86.6%). SF-36 scores averaged 50.6 postoperatively. CONCLUSIONS:When feet with atraumatic tarsometatarsal osteoarthritis are classified into four main categories based on associated deformities, appropriate concurrent procedures can be done with high satisfaction and improved function scores. Pes planovalgus feet, in particular, may benefit from concurrent procedures with improved radiographic measures.

BACKGROUND:Lengthening of the lateral column is commonly used for reconstruction of the adult and pediatric flatfoot, but can result in supination of the foot and symptomatic lateral column overload. The addition of a medial cuneiform osteotomy has been used to redistribute forces to the medial column. The combined use of a lateral column lengthening and medial cuneiform osteotomy in a reproducible cadaver flatfoot model was evaluated. METHODS:Twelve cadaver specimens were physiologically loaded and each was evaluated radiographically and pedobarographically in the following conditions: 1) intact, 2) severe flatfoot, 3) lateral column lengthening with simulated flexor digitorum longus transfer, and 4) lateral column lengthening and flexor digitorum longus (FDL) transfer with added medial cuneiform osteotomy. The lateral column lengthening was performed with a 10-mm foam bone wedge through the anterior process of the calcaneus, and the medial cuneiform osteotomy was performed with a dorsally placed 6-mm wedge. RESULTS:Lateral column lengthening with simulated FDL transfer on a severe flatfoot model resulted in a significant change as compared with the flatfoot deformity in three measurements: in lateral talus-first metatarsal angle (-17 to -7 degrees; p<0.001), talonavicular angle (46 to 24 degrees; p<0.001), and medial cuneiform height (16 to 20 mm; p<0.001). Lateral forefoot pressure increased from 24.6 to 33.9 kPa (p<0.001) after these corrections as compared with the flatfoot. Adding a medial cuneiform osteotomy decreased the lateral talar-first metatarsal angle from -7 to -4 degrees, decreased the talonavicular coverage angle from 24 to 20 degrees, and increased the medial cuneiform height from 20 to 25 mm. After added medial cuneiform osteotomy, lateral pressure was significantly different from that of the flatfoot (p=0.01) and was not significantly different from that of the intact foot (p=0.14). Medial forefoot pressure was overcorrected as compared with the intact foot with added medial cuneiform osteotomy. CONCLUSIONS:Lateral column lengthening increased lateral forefoot pressures in a severe flatfoot model. An added medial cuneiform osteotomy provided increased deformity correction and decreased pressure under the lateral forefoot.

BACKGROUND:Tibiotalar arthrodesis is the most common treatment of end-stage symptomatic ankle arthritis, but concerns exist about late findings of adjacent tarsal joint osteoarthritis. The purpose of this study was to evaluate the changes of pressure in the talonavicular, subtalar, and calcaneocuboid joints before and after rigid tibiotalar joint immobilization and at different levels of tibiopedal dorsiflexion. METHODS:Twelve cadaver foot specimens were cyclically loaded on a servohydraulic test frame to 700 N. Joint contact pressure, peak pressure, and contact area in the three tarsal joints were measured before and after tibiotalar joint immobilization with three 6.5-mm screws to simulate ankle arthrodesis. Measurements were obtained at tibiopedal dorsiflexion angles of 0, 10, 20, and 30 degrees in normal ankle joints and at dorsiflexion angles of 0, 10, and 20 degrees in fixed tibiotalar joints. Paired Student's t-tests and one-way ANOVA with repeated measures were used to analyze the data. RESULTS:Joint contact pressures did not show any statistically significant difference for the talonavicular and calcaneocuboid joints in the intact ankle. Contact pressures in the talonavicular and calcaneocuboid joints showed significant differences between 0 and 10 degrees and between 0 and 20 degrees of dorsiflexion (p<0.05) in the fused ankle specimens. Comparison of the contact pressure of the talonavicular and the calcaneocuboid joints between the intact and the fused ankle specimens showed a significant difference at 10 and 20 degrees of dorsiflexion (p<0.05). Subtalar joint contact pressure in the intact ankle showed a significant difference between 0 and 30 degrees of dorsiflexion (p<0.05). CONCLUSIONS:These changes in joint pressures and contact area are consistent with findings of transverse tarsal joint arthritis seen in clinical studies. The current findings suggest that a substantial pressure increase in the talonavicular and calcaneocuboid joints at tibiopedal dorsiflexion levels simulating a late stance phase of the gait cycle may be responsible for the secondary tarsal joint degeneration occurring in late ankle arthrodesis.

BACKGROUND:Biomechanical studies on retrograde intramedullary fixation for tibiotalocalcaneal fusion have been reported, but no studies have investigated dorsiflexion stiffness, load-to-failure, fatigue endurance, and plastic deformation using different distal screw orientations. Also, no studies have examined the effect of bone density on different distal screw orientations while using a fatigue loading mode. METHODS:Eight matched pairs of cadaver legs were used. In one leg from each pair an intramedullary nail was inserted with lateral-to-medial distal screws and in the other with posterior-to-anterior screws. These samples underwent dorsiflexion fatigue testing with determination of initial and final stiffness, load-to-failure, and degree of plastic deformation at failure. DEXA scanning was done of each cadaver specimen to determine bone mineral density. Statistical analysis was performed using the Student t-test and a Pearson correlation. Significance level was set at p < 0.05. RESULTS:The specimens with posterior-to-anterior screws had a significantly higher fatigue endurance load-to-failure (1130.0 +/- 362.0 N compared to 801.0 +/- 227 N, p = 0.01). They also had significantly higher final stiffness (203.1 +/- 23.1 N/mm compared to 146.6 +/- 46.2 N/mm, p = 0.05) and lower plastic deformation (2.4 +/- 1.5 mm compared to 3.8 +/- 2.3 mm, p = 0.04). There was a statistically significant correlation between bone mineral density and the difference in construct deformation with posterior-to-anterior and lateral-to-medial screw orientation (r = 0.76, p = 0.03). CONCLUSIONS:In this biomechanical investigation of tibiotalocalcaneal arthrodesis with intramedullary nail fixation, posterior-to-anterior distal screw orientation provided more stable fixation than lateral-to-medial screw orientation.