Faculty Bibliography

BACKGROUND:Charcot arthropathy is a chronic, progressive destructive process affecting bone architecture and joint alignment in people lacking protective sensation. The etiologic factors leading to progressive bone resorption have not been elucidated. The purpose of this study was to histologically examine surgical specimens with Charcot arthropathy for cell type and immunoreactivity of known cytokine mediators of bone resorption. METHODS:Tissue samples of 20 specimens with known Charcot arthropathy were stained for Hematoxylin and Eosin (H&E) to quantify cell type. Nine of the specimens were stained with interleukin-1 (IL-1) antibody, nine with tumor necrosis factor (TNF) alpha antibody, and nine with interleukin-6 (IL-6) antibody. Distribution of staining was graded as focal (less than 10% of cells), moderate (10% to 50% of cells), and diffuse (more than 50% of cells) by two independent investigators. Inflammatory cells in tissue sections of rheumatoid synovium served as a positive control. RESULTS:Osteoclasts were seen in excessive numbers lining the resorptive bone lacunae. There was a disproportionate increase in osteoclasts to osteoblasts in the Charcot-reactive bone. In each case, osteoclasts demonstrated immunoreactivity for IL-1, IL-6 and TNF-alpha with a grade of moderate or diffuse reactivity. CONCLUSION/CONCLUSIONS:The findings of excessive osteoclastic activity in the environment of cytokine mediators of bone resorption (IL-1, IL-6, and TNF-alpha) suggest enhanced bone resorption through the stimulation of osteoclastic progenitor cells as well as mature osteoclasts. Alteration in the synthesis, secretion, or activity of these important regulatory molecules through the use of pharmacologic agents may, in turn, alter bone remodeling and loss and lead to accelerated healing without collapse or malalignment.

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.

BACKGROUND:A change in screw orientation in fixing the chevron proximal first metatarsal osteotomy was noted anecdotally to improve fixation strength. The authors hypothesized that plantar-to-dorsal screw orientation would be more stable than the conventional dorsal-to-plantar screw orientation for fixation of the chevron osteotomy. The purpose of this study was to determine if the load-to-failure and stiffness of the chevron type proximal first metatarsal osteotomy stabilized using plantar-to-dorsal screw fixation were greater than with the more conventional dorsal-to-plantar screw fixation method. METHODS:One foot from each of eight matched cadaver pairs was randomly assigned to one of two groups: 1) fixation with a dorsal-to-plantar lag screw or 2) fixation with a plantar-to-dorsal lag screw. A proximal chevron osteotomy was then created using standard technique and the metatarsal was fixed according to previously established method. The bone was potted in polyester resin, and the construct was fitted into a materials testing system machine in which load was applied to the plantar aspect of the metatarsal until failure. The two groups were compared using a two-tailed Student t test. RESULTS:The average load-to-failure and stiffness of the chevron osteotomy fixed with the plantar-to-dorsal lag screw were significantly greater (p < 0.05) than the group fixed with more conventional dorsal-to-plantar lag screws. CONCLUSION/CONCLUSIONS:Plantar-to-dorsal screw orientation was more stable than the conventional dorsal-to-plantar screw orientation for fixation of the proximal chevron osteotomy. Plantar-to-dorsal screw orientation should be considered when using the chevron proximal first metatarsal osteotomy.

BACKGROUND:Metatarsalgia of the second ray is a common problem associated with disorders of the first metatarsal. It also occurs after the operative treatment of those disorders. Plantar pressure changes from alteration of the static and dynamic structure of the forefoot may be associated with this condition. This study evaluated changes in plantar forefoot pressure especially under the second metatarsal head after three operative procedures on the first ray. METHODS:Each of 12 cadaver foot specimens was cyclically loaded on the servohydraulic MTS Mini Bionix test frame (MTS Systems Corp., Eden Prairie, MN) with traction on the Achilles tendon. Plantar forefoot pressure was measured by the F-scan system (Tekscan, Inc., S. Boston, MA) with the foot intact, after a first metatarsal base dorsal closing-wedge osteotomy with 5-mm base length to simulate dorsal malunion, and after 5-mm and 10-mm metatarsal shortening procedures. Paired Student t-test analysis was used to compare data for the intact foot with data after each intervention. One form of Bonferroni's correction was done to establish a new alpha level to tighten the analysis and to compensate for multiple paired Student t-tests. The significance level was calculated to be 0.016 based on an original alpha level of 0.05. RESULTS:As compared with the intact foot, all three procedures on the first metatarsal resulted in significant decreases in plantar pressure under the first metatarsal head (p < 0.016). Plantar pressure under the second metatarsal head increased significantly as compared with the intact foot (p < 0.016) after all three procedures. Pressures under the third-fourth metatarsal heads increased significantly compared with the intact foot after the 5-mm and 10-mm shortenings (p < 0.016). Plantar pressure under the fifth metatarsal did not change significantly after any of the three procedures. CONCLUSIONS:Dorsiflexion osteotomy and shortening of the first metatarsal are associated with significant forefoot plantar pressure changes in a cadaver model.

BACKGROUND:The goal of this study was to identify pressure changes throughout the peroneal groove after a groove deepening procedure. We hypothesized that pressures would decrease. METHODS:Twelve fresh-frozen foot and ankle specimens were used. A thin pressure strip containing four sensor pads was secured within the peroneal groove with pads 1 through 4 positioned at the calcaneofibular ligament (CFL) and at the distal, middle, and proximal groove, respectively. The midstance phase of gait was simulated with loads applied to the plantar foot and posterior tibial tendon and to the peroneus longus and brevis tendons. Pressures were recorded with the ankle in neutral, plantarflexion, dorsiflexion, inversion, and eversion. Groove deepening was done by osteotomizing the posterior fibular wall. Pressure readings were then recorded. Average pressures for each of the four sensor pads after the procedure were compared to those obtained before the procedure. RESULTS:The mean pressure overlying the CFL increased at all five ankle positions; however, these changes were not significant. Significant decreases in pressure were noted within the distal and middle groove at all ankle positions after the peroneal groove deepening procedure. Pressure within the proximal groove increased at all but one position, with a significant difference noted in neutral and plantarflexion. CONCLUSION/CONCLUSIONS:Pressures within the middle and distal peroneal groove significantly decreased after a groove deepening procedure. Combining this technique with peroneal tendon debridement may be advantageous for treatment of partial peroneal tendon tears or recalcitrant peroneal tendinitis.

BACKGROUND:With technological advances in ankle arthroplasty, there has been parallel development in the outcome instruments used to assess the results of surgery. The literature recommends the use of valid, reliable, and responsive ankle scores, but the ankle scores commonly used in clinical practice remain undefined. METHODS:An internet survey of members of the American Orthopaedic Foot and Ankle Society (AOFAS) was conducted to determine which three ankle scores they perceived as most commonly used in the literature, which ones they believe are validated, which ones they prefer, and which they use in practice. RESULTS:According to respondents, the three most commonly used scores were the AOFAS Ankle score, the Foot Function Index (FFI), and the Musculoskeletal Outcomes Data Evaluation and Management System (MODEMS). The respondents believed that the AOFAS Ankle score, FFI, and MODEMS were validated. The FFI and MODEMS are validated, but the AOFAS ankle score is not validated. CONCLUSIONS:Most respondents preferred using the AOFAS Ankle score. The use of the empirical AOFAS Ankle score continues among AOFAS members.

By using three-dimensional magnetic resonance image reconstruction, lateral displacement of the flexor hallucis longus tendon and sesamoid bones was made clearly visible in a living patient. This finding supports a biomechanical model related to disturbed muscle balance at the first metatarsophalangeal joint, which could play an important role in the pathogenesis of hallux valgus and metatarsus primus varus.

Despite reports of high nonunion rates for isolated talonavicular fusion, this procedure may be indicated for some patients, including those for whom increased stability of the talonavicular joint in triple arthrodesis is needed. In the biomechanical cadaveric study reported here, we evaluated fixation methods used to provide optimal stability of talonavicular arthrodesis. A physiologic 3-point loading model was used to measure dorsal displacement of the navicular on the talus with 1 or 2 cannulated 4.5-mm screws across the talonavicular joint both with and without one 7.3-mm cannulated screw across the subtalar joint. Statistically significant differences in displacement under cyclic loading to one-half body weight were found. Use of 2 talonavicular screws and no subtalar screw or 1 talonavicular screw plus 1 subtalar screw decreased the motion, as compared with use of 1 talonavicular screw and no subtalar screw.

BACKGROUND:Several different techniques have been used for fixation of first metatarsocuneiform (MTC) joint arthrodesis, a standard treatment for arthritis, instability, and deformity of the MTC joint. Improved plating systems using locking designs are now available, but no studies have yet compared this construct with other methods. We compared load to failure with a locking plate design versus standard crossed-screw fixation. METHODS:Ten matched pairs of fresh frozen cadaver feet were used. The bone density of each pair was measured with DEXA scanning. One foot of each pair was randomly assigned to have a dorsomedial Normed H titanium locking plate (Normed Medizin-Technik Vertriebs-GmbH, D-78501 Tuttlingen, Germany) applied to the first MTC joint. On the other foot of the pair, fixation of the first MTC joint was done with crossed ACE DePuy 4.0 (DePuy/Ace, Warsaw, IN) titanium cannulated screws. The first metatarsal and first cuneiform were then isolated and planted in an epoxy resin. The specimens were loaded to failure in a four-point bending configuration using a MTS Mini Bionix test frame (MTS Systems Corp., Eden Prairie, MN). Failure was defined as displacement of more than 3 mm at the arthrodesis site. The Student t-test was used to determine any observed differences, with significance set at p <or= 0.05. RESULTS:The mean maximal load to failure was 140.08 N (SD +/- 77.1) for screw fixation alone and 58.09 N (SD +/- 11.86) for the H-locking plate. This difference was statistically significant (p = 0.008). The mean stiffness of the construct for screw fixation alone was 83.10 N/mm (SD +/- 49.8) and 19.96 N/mm for the H-locking plate. This difference also was statistically significant (p = 0.004). CONCLUSION/CONCLUSIONS:Screw fixation for first MTC arthrodesis created a stronger and stiffer construct than did the H-locking plate. This was likely due to the mechanical design of the implants. Compression across the MTC joint could be applied with the screws, but the plate relied on a fixed angle design with no compression.